Fantasy Racer: Lets spend money building the be-all, end-all road racer!

[Scargo]

I feel I'm getting a wag of the finger from "mother" every time I talk about crazy or expensive. So I've built this sandbox for us to play in.
Let's talk about reliable power and BBKs and suspension options. Let's talk about crazy ideas for cooling and AWIC setups. What can we do for perfect weight distribution and a shock/spring combo for an average smoothness track? Anything goes as long as it is legal for NASA ST1 (or SCCA's equivalent to ST1).
Can we spend money, almost like it grows on trees, and be competitive with the big boys? Can you say, like the owner of the monkey that is pissing on the cash register, "it's going to run into money!" ?
I want to see plausible, doable ideas that make sense for the capable home-builder, with a pretty big budget. Let's fab, machine, weld or "buy our way into" a hands-down class killer car... Let's stretch our imagination!
Who is willing to contribute? I say there's no rules beyond what I've stated above. It's not my thread; it's OUR thread to play in and use our imagination and our expertise. I really welcome expertise! I'm sure you will, too!
So, I can't even say "no attitudes" if somebody argues with you (or me) either. Let's see what we can build, as if it were a mechanical engineering class project with an angel backing us.

[Scargo]

Reserved for future.. and I'm waiting for the first brave contributor.

[DruOdil]

OK, CF the whole body $$$$$$$$$$$$

[Scargo]

Does that really contribute anything meaningful we can use? It's like saying, "Look, I have wings, I can fly!". What an auspicious start.

[Greg G]

OK, I will bite a little.

Whatever we build, seeing that it is to be the cat's a$$, MUST have a "flappy-paddle" gearbox. 8 speeds and it must be intelligent enough that if I am blasting down the front stretch of Miller M/S Park at 180+, and I need, say 2nd gear for turn one, then all I must do is "flap the paddle" 7 times and the gearbox, along with the engine electronics, will get it there perfectly on it's own. No further input from the driver.

[Doowop]

well, besides having a super built motor and transmission, having a set of custom built Ohlins shocks built, Brembo brakes, it would require some more testing to see what would need to be modified. Seeing that there aren't many cars actually on the tracks, there are not many feedbacks as far as weight distribution, suspension geometry, etc... Also, money can buy a lot of technology, but I will be building an 818R because it doesn't have the technology of new cars and will be a pure race car where driving is everything. Cars that drive themselves are not really what I am looking for.
Engineering a car does not work only in theory, a lot of R&D and testing needs to be done in real life situations.
Great thread idea though. I'd like to see what people think on that.

[gwarden]

Ok can't say I like the flappy paddle idea but could go for 6 speed manual

[Scargo]

I'm disappointed so far. I didn't mean this to be a gag thread. Perhaps you should write for The Onion. "Eight-speed carbon fiber flappy-paddle wins Daytona 500."

[Scargo]

Ok can't say I like the flappy paddle idea but could go for 6 speed manual I want a close-ratio, six-speed sequential box*. Please FFR, finish the pieces for a six-speed?
*Sequential is $10-15 K from what I gather. Not sure if it is a good investment for NASA level racing.

[Wayne Presley]

Cosworth long block
Cosworth high volume intake
Quaife sequential 6 speed, air shifted ( PPG dog box)
Garrett GT 3076R turbo
VCP air to water intercooler
Wilwood 6 piston calipers over carbon discs (2 piece iron rotor/aluminum hat)
Wilwood tripple master cylinders
full carbon body
Center hub Yongblod wheels
Tomei equal length headers
Motec engine mangement, logger, and dash (Electromotive TEC-GT with AIM MXL Pista datalogger dash, saves $3500 over MoTec)
1250cc injectors
Full carbon body
DJ Engineering dual element carbon wing (APR GT-250 wing)
Carbon splitter
Full belly pan with custom carbon diffuser
Exhaust vents on rear of front fender
passenger side cockpit cover

[DruOdil]

Does that really contribute anything meaningful we can use? It's like saying, "Look, I have wings, I can fly!". What an auspicious start.

You sound like mother, put your finger away.

[Santiago]

So far I second Wayne's proposal, but we're missing a few key elements.

As my signature suggests, we need a wider track (3" minimum), and likely a wider one in the back. So that means flared fenders to go with those vented fenders. The rear bumper should be extinct, save the light panel (see some of the more serious Lotus builds).

Next up on the signature theme, do everything possible to drop the center of gravity. Start with a dry sump system that can make the exhaust manifolds the limiting factor in lowering the engine. A 3" drop would be nice to see. Plan to cut the supplied engine mounts off, trim as necessary, then re-weld.

Tires should be as wide as testing shows benefits (full slick of course). I'd bank on at least 275mm wide in back.

Aero should be DTM level, or at least inspired by it. Hood should have a perimeter-sealed direct vent off the radiator (see C6-R).

That...and a full team to track test for several months.

Best,
-j

[Greg G]

So I've built this sandbox for us to play in.
Anything goes as long as it is legal for NASA ST1 (or SCCA's equivalent to ST1).

I want to see plausible, doable ideas that make sense for the capable home-builder, with a pretty big budget. Let's fab, machine, weld or "buy our way into" a hands-down class killer car... Let's stretch our imagination!
[/I] I say there's no rules beyond what I've stated above. It's not my thread; it's OUR thread to play in and use our imagination and our expertise. I really welcome expertise! I'm sure you will, too!
So, I can't even say "no attitudes" if somebody argues with you (or me) either. Let's see what we can build, as if it were a mechanical engineering class project with an angel backing us.


I'm disappointed so far. I didn't mean this to be a gag thread. Perhaps you should write for The Onion. "Eight-speed carbon fiber flappy-paddle wins Daytona 500."

Gag thread? That is EXACTLY what this is...and I mean that in a good and fun way. You said "buy our way","no rules" and "no attitudes (me either)" with a "big budget" and "engineering with God on our side." That is what I and another posted, and you criticize what was posted. Sorry dude.

Perhaps you should have just posted your "dream car" under the same theme, and asked others to build their own, COMPLETE, dream car.

[Canadian818]

Just make it feasible guys, no imaginary gearboxes.

How about....is there any DSG gearboxes that "could" work? GTR? 997? While we're at it, what would be the dream engine? How about a tiny high reving V8 like in the V8 Aerial Atom?

Wide body of course, think like what Hennessay did to the lotus body.

Not sure 6 pots will be needed if we're using carbon brakes, let's use 4 pots to save weight.

I'm guessing we're having custom aluminum uprights to mount those centre lock wheels?

[Santiago]

A feasible engineering class project taken from FSAE, speed sensitive aero devices. Give us max downforce at "low speed" where the majority of fast corners would be taken then transition to minimum drag settings for top speed on the straights. Come to think of it, they may have pinned this to LatG instead of speed. The car becomes like a living animal...smart aero that reacts to actual demands.

Did I mention a team to work on it? =)

Oh, and air jacks! :cool: There must be air jacks...

[Turboguy]

Cosworth long block
Cosworth high volume intake
Quaife sequential 6 speed, air shifted ( PPG dog box)
Garrett GT 3076R turbo
VCP air to water intercooler
Wilwood 6 piston calipers over carbon discs (2 piece iron rotor/aluminum hat)
Wilwood tripple master cylinders
full carbon body
Center hub Yongblod wheels
Tomei equal length headers
Motec engine mangement, logger, and dash (Electromotive TEC-GT with AIM MXL Pista datalogger dash, saves $3500 over MoTec)
1250cc injectors
Full carbon body
DJ Engineering dual element carbon wing (APR GT-250 wing)
Carbon splitter
Full belly pan with custom carbon diffuser
Exhaust vents on rear of front fender
passenger side cockpit cover

x2

+ a set of custom valved Moton 3-way shocks
+ air jacks all around.

Looks like we're done here :)

[Canadian818]

x3 on air jacks!

[Scargo]

I appreciate all the ideas. Some I want to follow-up on. I think "just make it feasible" is another way of expressing what I wanted. I said there were few rules. I stated them: "I want to see plausible, doable ideas that make sense for the capable home-builder, with a pretty big budget. Legal for NASA". Reread my opening statement before you get butt-hurt.

I want to use a six-speed. I'll at least do a fifth and sixth gear upgrade. (http://www.flatironstuning.com/p-1943-jdm-close-ratio-5th-and-6th-plus-synchro-up-grade-for-6mt.aspx) To quote: This will help turn your STI transmission into a close ratio gear box, and improve shifting between 4th, 5th, and 6th gear. This also con Use [sic] to improve on problematic 4th, 5th, 6th synchro performance. This kit also converts your USDM/Euro gearbox to proper Group N ratios.
I am interested in the wheels Wayne mentioned. Jongbloed? Like this?:26272
I was thinking of the Wedsport TC105N26273(18 lbs for an 18x 10.5) or custom wheels like the CCW T1000s26279.
I was going to do something like a Mustang II or Chevy aluminum spindle (with a C-5 bearing and late model C-5~C-6 BBK capable)which requires a new LCA. I'm looking at a racing version with all Heim joints for a BRZ. 26282or this from RCE: 26280

Inboard shocks...26284

Ditto on air jacks! $1000 for three.

[Scargo]

Cosworth long block
Cosworth high volume intake
Quaife sequential 6 speed, air shifted ( PPG dog box)
Garrett GT 3076R turbo
VCP air to water intercooler
Wilwood 6 piston calipers over carbon discs (2 piece iron rotor/aluminum hat) I don't understand this. Seems like a contradiction.
Wilwood tripple master cylinders
full carbon body
Center hub Yongblod wheels
Tomei equal length headers
Motec engine mangement, logger, and dash (Electromotive TEC-GT with AIM MXL Pista datalogger dash, saves $3500 over MoTec)
1250cc injectors
Full carbon body
DJ Engineering dual element carbon wing (APR GT-250 wing)
Carbon splitter
Full belly pan with custom carbon diffuser
Exhaust vents on rear of front fender
passenger side cockpit cover

I have a few questions.:o
Quaife also makes an LSD: What's the ultimate racing LSD? Guard Transmission, OS Giken or other?
Engine management/datalogging: Motec's the ultimate $$ and Electromotive's just as good? Where does AEM, Racepac, etc. figure in?
Is there a thread (here on the FFR forums or elsewhere) that covers this thoroughly? I'd love to see LINKS so I can make some sense of the electronics issue. I will not use the OEM ECU. There's so many choices and combos. Definitely datalogging capability. Something that's easy to learn to tune with. A good, single dash display. I will not have a tuner guru on my team so I would like to keep complexity down. I know this isn't ultimate racer stuff, but for me it's being realistic.
Carbon splitters: What about Tegris, like NASCAR and others use?

[Scargo]

Floor-mounted, fully adjustable pedal box. (http://tiltonracing.com/product/900-series-floor-mount-pedal-assembly/) PEDALBOX RPB0001 (http://www.racingpedalboxes.com/#!products/vstc2=pedal-boxes) Brake bias valve on the dash or console.
Blade style anti-sway setup. Adjustable on the console or dash.
26292
26293Front for a Porsche (Elephant Racing).

It is my impression that anything you can adjust, regarding the suspension, aero or boost (changing the WHP) is illegal while you are on the track. Adjusting brake bias seems to be legal. So much for a Formula 1 style of car.

[Santiago]

I'm reasonably sure that you can adjust anti-sway bars legally in NASA. But I think you may be right about the aero at least for some classes, and right about boost for all classes.

FWIW, a carbon splitter is going to be the lightest option out there...Tegris and the like are appreciated for the lower replacement cost.

As for the ECU, the simplest option is probably still the OEM one. You can get all/most of the data logging with something like a mid-to-higher end AIM unit.

Best,
-j

[Greg G]

FWIW, a carbon splitter is going to be the lightest option out there...Tegris and the like are appreciated for the lower replacement cost.


Any good sources/pricing for the Tegris? I looked it up briefly a while back and, though it looked cheaper/easier than carbon, it was still some pricey stuff...unless I looked at the wrong thing :)

[Scargo]

I doubt it. I found that there was only one source (http://powerstreamindustries.com/index.asp). At least, this is all I found from perhaps a year ago. You can buy the raw material and cut it yourself.

[Greg G]

I doubt it. I found that there was only one source (http://powerstreamindustries.com/index.asp). At least, this is all I found from perhaps a year ago. You can buy the raw material and cut it yourself.

Yep, just as I thought...a bit too pricey! Thanks for the link!

[Wayne Presley]

I have a few questions.:o
Quaife also makes an LSD: What's the ultimate racing LSD? Guard Transmission, OS Giken or other?
Engine management/datalogging: Motec's the ultimate $$ and Electromotive's just as good? Where does AEM, Racepac, etc. figure in?
Is there a thread (here on the FFR forums or elsewhere) that covers this thoroughly? I'd love to see LINKS so I can make some sense of the electronics issue. I will not use the OEM ECU. There's so many choices and combos. Definitely datalogging capability. Something that's easy to learn to tune with. A good, single dash display. I will not have a tuner guru on my team so I would like to keep complexity down. I know this isn't ultimate racer stuff, but for me it's being realistic.
Carbon splitters: What about Tegris, like NASCAR and others use?


the stuff in the () shows a lower cost but equally effective substitute.

[Mechie3]

Anyone know how big a Porsche flat 6 is compared to a Subie Flat 4 (or 6)? Certainly expensive, but budget isn't the rule, right? You can get a nice PDK trans to go with it if you want.

[Jaime]

If there's no budget, contract someone to design and build an engine and transmission. People do it all the time... Harley Davidson did it at a production scale by having Porsche design its water cooled engine. Kenny Roberts did it in GP motorcycle racing by assembling his own team to build a bike from scratch (Proton). He claimed the costs of building the bike were one of the smaller expenses he incurred.

I'd build a transmission similar to what Ferrari did... computer controlled gearbox. They treated it like robotic welding equipment - have an expert drive it and record what they did. Then, mimic his movements when the driver pushes the shift paddles. No reason you couldn't make it drive like an automatic, too.

[Scargo]

I think I said "almost like it grows on trees". :rolleyes: I might entertain a Porsche combo like Mechie3 mentioned. I think it's the ex-rice rocket biker in me.
Sure would like to continue the discussion on alternate powerplants and trannys.
Had a M3 with SMG and almost bought a Boxster with PDK.
LOL. I bought the '11 STi instead. Now look at me...
I am not that familiar with what else there might be in the way of a comparable, readily available, powerplant and tranny combo. The Boxster engine is NA I believe. Other Porsche engines would be overkill or heavier (I assume) for ST1 anyway. SVX 6 cylinder? The best for price and power for ST1 may be a two liter Subaru motor, but then you don't get a sequential gearbox... Could the 2014 Honda Valkyrie 1,832cc motorcycle engine be a candidate if turbocharged? It's at a puny 104 HP stock. Honda engines seem to pack a lot of punch per cc.

[Santiago]

With no budget constraints, you could get a Hartley V8...

400 hp @ 10,000 RPM
245 tq @ 7,500 RPM
Naturally aspirated
Dry sump (4-stage)
Engine weight: 200 lbs

Sweetness.

-j

[Jaime]

I think I said "almost like it grows on trees". :rolleyes:OK, more down to earth...

I used to be into the motorcycle scene. A Suzuki Hayabusa engine and transmission weight about 150 pounds and make 250HP at the wheel with a fairly modest amount of work. If you put a turbo on it, 400HP is easy. Motorcycle transmissions are very easy to auto-shift, so you could whip up a paddle shifter solution for about $1500.

[Greg G]

OK, more down to earth...

I used to be into the motorcycle scene. A Suzuki Hayabusa engine and transmission weight about 150 pounds and make 250HP at the wheel with a fairly modest amount of work. If you put a turbo on it, 400HP is easy. Motorcycle transmissions are very easy to auto-shift, so you could whip up a paddle shifter solution for about $1500.

Is there any concern with durability with this setup? I would think (an assumption, but reasonable), that the engine/transmission are designed for a 4-500lb m/c with a 200lb +/- fat guy like me beating on it like a rented mule, and wouldn't live too long in an 1800+lb car with me beating on THAT like a rented mule. I was (long ago I admit) a service manager for a m/c dealership and saw some truly epic damage on all flavor of sportbikes. Now, I do know that there are mini-race cars out there with similar setups, as well as Legend cars, Atom-types, etc. so I may be WAY off base here...

Even if durability IS there and reasonable, I can't imagine that the clutches would last too long with that kind of weight they are pushing, as well as additional H/P. It still amazes me how small the clutches are on a m/c, and how much abuse they can withstand!

[Jaime]

Could the 2014 Honda Valkyrie 1,832cc motorcycle engine be a candidate if turbocharged? It's at a puny 104 HP stock. Honda engines seem to pack a lot of punch per cc.Stay away from long stroke motors. Motorcycle engines are limited by piston speed, so big power comes from bore and cylinder count. Big inch twins in the two liter range are lucky to make 150HP, the Triumph Rocket III get about 160HP from 2 liters. By contrast, a BMW 1000RR makes 180 at the rear wheel in factory form with half the displacement. But, the Hayabausa is still the king of potential power because Suzuki doesn't play the shave-every-extra-gram-we-can game with it.

[Jaime]

Even if durability IS there and reasonable, I can't imagine that the clutches would last too long with that kind of weight they are pushing, as well as additional H/P. It still amazes me how small the clutches are on a m/c, and how much abuse they can withstand!I'm always amazed that cars use single plate clutches. My Hayabusa had a 17 plate clutch. Sure they were smaller, but....... 17!

I had a big bore kit it mine and was putting over 200 to the rear wheels and it was perfectly reliable for the 20,000 miles that I drove it. The transmissions and bottom ends are good to 400HP as is. Over 300 you should upgrade head bolts. I've seen dyno queens that make 750HP and stay together.

[Scargo]

This guy at Precison Chassisworks has a conversion kit to mate a Subaru motor to a Porsche tranny. Guess what that means?
http://www.youtube.com/watch?v=g4cVMmJKyLg
This Subaru motor in a Boxster project (http://www.precisionchassisworks.com/boxstersubaru-engine-conversion.html) he did is pretty amazing. See photo below.
I was thinking of something along these lines for a possible exhaust routing, but not have the turbo that far away. Seems you'd loose a lot of heat energy along the way.
http://www.precisionchassisworks.com/uploads/2/5/1/9/2519425/7471293_orig.jpg

[Santiago]

I had thought about a custom exhaust routing, but wasn't sure you had chassis clearance on the 818 since all relevant tubes seem to converge at an angle that is most narrow at the bottom. I thought it might be nice to have the turbo lower for weight, but it looks like you'd be trading off a greater length of outlet tubing in the trade. What was your interest in the custom exhaust? Heat management?

Just curious.

Best,
-j

[THE ITALIAN]

I would do the above, but FLARE the entire back section for massive rear tires. If I build this car, I will do this.
I did this to a 240 Z and it was awesome plus added some traction.

[longislandwrx]

I would do the above, but FLARE the entire back section for massive rear tires. If I build this car, I will do this.
I did this to a 240 Z and it was awesome plus added some traction.

I've been looking at flares after watching the Alfa on Top Gear last night. I think another 2" all around would be awesome. Cant wait to hang the body.

[THE ITALIAN]

I would do the above, but FLARE the entire back section for massive rear tires. If I build this car, I will do this.
I did this to a 240 Z and it was awesome plus added some traction.
I've been looking at flares after watching the Alfa on Top Gear last night. I think another 2" all around would be awesome. Cant wait to hang the body.

I forgot to add; I also put a 350 HP V8 in that 240 Z

You would slow down the air a little with flares, but what you can gain in cooling duct flow would be worth it for a rear engine - according to this thread, 400 HP Cosworth, who cares about a little aero friction? I would be more concerned about cooling the beast & it's carbon disc$.

I think the car has qualified into the UNLIMITED CLASS at this point, swoosh ! a 700 HP Ultima just passed you !

[C.Plavan]

Once I finish my R- You could see a Porsche motor in it at a later date. I have a few laying around. I just want to play with it now. :)

[johngeorge]

What is the racing format? Wheel to wheel sprint racing? Enduro racing? Time trial?

[Scargo]

I had thought about a custom exhaust routing, but wasn't sure you had chassis clearance on the 818 since all relevant tubes seem to converge at an angle that is most narrow at the bottom. I thought it might be nice to have the turbo lower for weight, but it looks like you'd be trading off a greater length of outlet tubing in the trade. What was your interest in the custom exhaust? Heat management?

Just curious.

Best,
-j

Heat management is a big part. I do not like how the exhaust wraps around the oil pan. It heats everything including the oil filter. It's often worse if you install aftermarket manifold.
I intend to do dry sump, but the quicker you get the exhaust to the turbo the better, and the out! I think the bottom cross-member (between the engine and where a stock FFR gas tank would go) can me moved slightly to allow for an undermount turbo. (http://www.tuspeed.com/tuspeed-low-mount-subaru-turbo-kit-p-1951.html)
26345
This is close to what I'm thinking of, but lacks dual blow-off valves and is designed to miss the oil pan, which for me will not be an issue with DS. I think I will come out the passenger side with the exhaust, in front of the rear wheel.
The other image shows some potential for placing the turbo low, in the area where the down-pipe might normally be.
G

[THE ITALIAN]

"Anything goes as long as it is legal for NASA ST1 (or SCCA's equivalent to ST1)."
I think we've gone way past the original post.

[Xusia]

I've been in the sportbike scene for a great many years. I thought very seriously about using a motorcycle engine in my 818 (before I bought a donor), but I came to the conclusion I just didn't think the components would handle the extra weight very well. A motorcycle simply can't stress a transmission like a car can. 1)You have limited traction (much less than a car). 2)Even if you have traction, the bike will wheelie. Therefore, the transmission just won't experience the same stress as it would in a much heavier application with a lot more traction.

Even if the transmission issue could be overcome, the "oversquare" configuration that delivers such high HP with so little displacement has an Achilles heel: Low torque. The lower torque isn't an issue in sportbikes because of the ridiculously low weight. At 4x the weight of a sportbike, though, the torque deficit will have a noticeable impact on performance in an 818 (in a negative way).

I'd still LOVE to see this done (supercharged ZX-14 engine would be my choice), but I just don't think it would be competitive as an "ultimate racer." But would it be neat/cool? You bet!!

[Bob_n_Cincy]

I've been in the sportbike scene for a great many years. I thought very seriously about using a motorcycle engine in my 818 (before I bought a donor), but I came to the conclusion I just didn't think the components would handle the extra weight very well. A motorcycle simply can't stress a transmission like a car can. 1)You have limited traction (much less than a car). 2)Even if you have traction, the bike will wheelie. Therefore, the transmission just won't experience the same stress as it would in a much heavier application with a lot more traction.

Even if the transmission issue could be overcome, the "oversquare" configuration that delivers such high HP with so little displacement has an Achilles heel: Low torque. The lower torque isn't an issue in sportbikes because of the ridiculously low weight. At 4x the weight of a sportbike, though, the torque deficit will have a noticeable impact on performance in an 818 (in a negative way).

I'd still LOVE to see this done (supercharged ZX-14 engine would be my choice), but I just don't think it would be competitive as an "ultimate racer." But would it be neat/cool? You bet!!

Hi xusia
Piontek Engineering did that about 15 years ago. They used a "1325cc Suzuki motorcycle engine. It was mounted mid-ship and used chain drive to a differential. A trip the drag strip resulted in a 12.8 second quarter mile at 112 mph" Notice, no doors.

26353

26354

[Scargo]

This should give you hours of fun. http://thekneeslider.com/motorcycle-powered-cars/ You are right, the issue seems to be lack of enough torque for a 1,800~1,900 lb car.
The Caterham Super 7 CSR Cosworth is powered by a 260 hp, 2.3 litre inline four (http://en.wikipedia.org/wiki/Straight-4) Ford (http://en.wikipedia.org/wiki/Ford) Duratec (http://en.wikipedia.org/wiki/Duratec) tuned by Cosworth (http://en.wikipedia.org/wiki/Cosworth), but only makes 200lb ft @ 5250rpm. Sigh.
I calculate I can develop 550 FPT @ 4,500 RPM!(470 Crank HP/400 WHP).

[Scargo]

Ride Height (I'm working on my Ultimate Front Suspension design)
What is the "ultimate ride height? In Nascar, the splitters scrape. Obviously you need something akin to a couple of inches of bump in the suspension, but where does the aero performance really kick in?
What's the minimum we're at now with 17" low profile race tires (in the front)?
I think the car needs drop spindles, but I don't know how much. I basically have 1" or 2" options. I don't have the dimensions of the upright. Can anyone give me the "dimension labeled as "130mm" in the photo? This is just for demonstration; I know it's not the WRX upright. Lower pivot point to spindle center. Just can't find this dimension anywhere.
Looks like the forum where this picture resides went down. I'm looking for the spindle centerline to lower balljoint pivot point dimension. Eyeballing it with a ruler would be fine.
http://www.locostusa.com/forums/download/file.php?id=4754&sid=352914a1f3a8de3efc046fdca9f80beb

[Scargo]

I got the dimension I needed thanks to Rasmus. I was looking for the rough dimension of the spindle centerline to the lower control arm pivot point. That vertical dimension turns out to be 85mm. Now I can compare that to workable, reasonably priced, light spindles that are out there.

[Santiago]

Ride Height (I'm working on my Ultimate Front Suspension design)
What is the "ultimate ride height? In Nascar, the splitters scrape. Obviously you need something akin to a couple of inches of bump in the suspension, but where does the aero performance really kick in?

For most cars that see track duty on full road courses (not autocross or dirt), the general consensus seems to be that aero kicks in (as in, measurable changes start) around 80mph and ramps up from there, with 100 mph being the point at which significant things are going on. A few complications here (or maybe, just things to consider):
1. These estimates depend heavily on what aero devices you are employing (this is why I ruled out dirt...have you SEEN the wings those guys run!)
2. The importance of the speeds should be mapped onto the tracks you'll visit most often

Ok, a word on that last point. Consider, if at your local track you'll never see a 120mph sweeper, then who cares what your aero gains are at that speed? Actually, as speeds go up on the straights, you kind of want the aero to go away. This is why drag becomes increasingly important at high speeds (think: 100+ mph straights). You may gain tons of downforce at those speeds, but unless there's a corner involved, what's the benefit? Few cars have so much raw power that they can spin the tires at 100mph shifting from 3rd to 4th (or whatnot), and this even with no aero assist at all. So downforce from aero devices becomes mostly irrelevant in the straights, except that it is accompanied by drag - which does take away from performance. All we really want in terms of downforce is "no lift" at high speeds ('cause lift is just never any fun). Thus, if they were legal everyone would run adjustable aero.

But maybe your question was really more "when do I have to worry that aero gains were going to require serious thought to how much it eats into bump travel" or something along those lines? That is, when will aero gains start to chew up my splitter? If that's what you were after, first see (1) above and second, figure you don't have to worry until 120+mph (and even that seems conservative - 150+mph is more likely where you're in for some large enough levels of downforce to worry).

If you're planning to run the aero that FFR offers, look at their published data on the aero testing, look at the distribution of front/rear downforce gained, and then calculate what sort of vertical travel would be involved with a given wheel rate. Unfortunately, we don't have published data on the wheel rates (spring rates tell you zip without a bunch more information - and in the end it may be easier to just measure this directly at the wheel). However, you might make an educated guess at it and play with the numbers.

For example, they published that at 100 mph they got 120 lbs of downforce in front and 164 lbs rear: 284 lbs total. Ok, 120 lbs divided by two wheels, 60 lbs more on each front wheel. If the wheel rate in front was 180 lbs/in (a WAG), then that extra 60 lbs would lead to 1/3" additional compression (somewhere in the neighborhood of 5/16"). Not a lot, but again, this is at 100 mph. At 150mph they showed 271lbs in front and 369 lbs rear: 640 lbs total. Now 271 lbs is putting about 135 lbs into each of the front tires. So you're seeing about 5/8" compression...in theory (there's a lot of assumptions built into the above, but I think they're modest).

Not sure if that helps. If you ended up riding the skid plates, I would think it just means it's time to up the spring rate and keep the car off the ground.

Best,
-j

[Scargo]

This is good stuff and what I'm looking for. Yes, I was thinking along the lines of how much shock travel do I have vs clearance, and what kind of spring rate keeps it off the tarmac for a little suspension travel at full tilt. Most of my tracks will only get me to 150 or so and few have really high-speed turns. WGI has one or two. Lime Rock, New Jersey... not so much and may not be worth huge aero.
I feel like the aero on my STi may not be helping, at my 7.8:1 P/W ratio. Though I now find that my turbo is sloppy and needs a rebuild, I felt like I was going slower on the straights, relative to before I added the aero and that my lap times did not go down.

I do not know where FFR's published data on the aero testing is... Do they have a portal for data on the track car?

[Santiago]

FFR put up a news article on the aero testing. You can see it here (https://www.factoryfive.com/whats-new/wind-tunnel-testing-the-new-factory-five-818/).

I think for most of us the supplied spring rates for the R are going to be a good start, even if we're upping our aero-game :rolleyes:. Of course, that doesn't mean much if you're trying to design your own suspension. You might want to try looking for rough calculations of the wheel rate from folks who have R-cars. You can find stuff on the web for this (the formula needed), but here's the short version of info you'll need:
- Spring rate
- Distance from LCA lower pivot to lower coil-over mount
- Overall length of LCA
- Angle of coil-over inclination
You're really only calculating the influence the geometry has on the spring rate to tell you what is going on at the wheel. That part of it is not too tough. The wildcard is the sway bar. That isn't so easy to calculate, which is why I said it was likely easier to just directly measure this off the car. Still, it's a small bar with long arms (all things told), and if your own front suspension plans involved a sway bar, just plan on similar diameters and arm lengths (or do the math to find equivalents) and you should be in the ball park of FFR's wheel rates doing the math. You just need someone to measure out a few things for you.

Best,
-j

[Scargo]

What I got from that article was this comment: In the end our best numbers came with the extra radiator ducts taped off, the new splitter with the air gap taped off, 5 degrees of wing angle, the rear diffuser in place, no side skirts, and a level ride height of 3-3/8 inch. The max downforce produced was 120 lbs front and 164 lbs rear at 100mph, this increases to 271lbs front and 369 lbs rear downforce at 150mph. The only concern with this set-up was cooling with the extra air inlets taped off, however we were able to test this configuration two days later in 97 degree weather at the track and the engine temperature was not affected.

Also, Jim Schneck sent me this regarding the blue FFR 818R car:
Front:
Motion ratio is .795
Shock angle correction: .906
Roll center: 2.8 inches (with 215/45/17 tires at 4.5 inch ride height)

Rear:
Motion Ratio: .877
Shock angle correction: .985
Roll center: 4.0 inches (with 255/35/18 tires at 4.5 inch ride height)

I don't know if the roll centers are the simplified "Force Based Roll Center" or not (as from the link from Racecartuner.com (http://www.racecartuner.com/03/304.html)).

[longislandwrx]

How much has to remain a 818?


Long rod destroker... low/close mount GTX35 turbo e85/e98. titanium exhaust dry sump, Sequential gearbox.. 22gallon cell. frame redone in chromoly. Traction control.



weight with driver under 1800.

sorry all over the place, just spitting out ideas.

[Xusia]

Actually, as speeds go up on the straights, you kind of want the aero to go away. This is why drag becomes increasingly important at high speeds (think: 100+ mph straights). You may gain tons of downforce at those speeds, but unless there's a corner involved, what's the benefit?

I don't plan on racing, but if I did, given the 818's low weight I'd be looking to keep it from (best case scenario) drifting because of side winds, or (worst case) flipping because a gust of wind got underneath it. <-- Happens to F1 cars even with aero down force...

[Santiago]

What I got from that article was this comment: In the end our best numbers came with ...a level ride height of 3-3/8 inch.
Also, Jim Schneck sent me this regarding the blue FFR 818R car:
Front:
Roll center: 2.8 inches (with 215/45/17 tires at 4.5 inch ride height)

Rear:
Roll center: 4.0 inches (with 255/35/18 tires at 4.5 inch ride height)


Hmmm...those figures are at odds with the wind tunnel tests. I know they were dialing things in there, so the 4.5" ride height may have been a carryover from the S-car's general development parameters. The R-cars are set up to drop 1", which would explain the published stats during those tests being over 1" lower.

Motion ratio and shock angle shouldn't be impacted by ride height (assuming you use the R-mount for the coil over).

[Scargo]

I don't care what kind of ideas you throw out. I still would like to see ideas that a non-pro shop could turn out. I think if you throw out the frame there wouldn't be much FFR left... It would be cool if they offered a better race frame upgrade.

Since this will be my first kit, I'm not going to diss anything yet. As said, it is fairly light.
However, could we get to a more optimal weight distribution?
I'm looking for the strong and light rear suspension pieces. Suggestions? Lateral arms: Mooresport (MSI) (http://www.mooresport.com/indexe.php/suspensions/impreza-rear-lateral-links)? Massive (http://www.massivespeedsystem.com/_massive_speed_system_/massive_racespec_lower_control_arm_set/mass111300/i-341925.aspx)?
Trailing arms: MSI again... (http://www.mooresport.com/indexe.php/products/suspension/impreza-rear-trailing-arms)
Cusco adjustables
26687
Aluminum Uprights: DJM (http://www.djm-motorsport.co.uk/Subaru%20-Rear-alloy-uprights%20.html)
I'm now looking for used, lightweight JDM or WRC rear housings. Anyone have any resources?

[Scargo]

...those figures are at odds with the wind tunnel tests.
I agree. I thought the race car was at 3.5". I'd like to go lower. How low? That's a very good question. I wonder how many tracks would tolerate 2.5 inches?
I don't think New Hampshire would and there's the rough boot toe at WGI.
If I do my fantasy front suspension I think I would design for 3" and have around a one inch range to play with.

[longislandwrx]

It's really too bad that Chromoly isn't an option... less than $1000 more for metal maybe a lot less in FFRs costs... and would probably save 120+lbs... you're not going to spend $1000 anywhere else and see that return.

I understand from an inventory standpoint, twice the pieces, but to dominate racing, you're going to have to pull out all the stops.

[longislandwrx]

I'm looking for the strong and light rear suspension pieces. Suggestions? I'm now looking for used, lightweight JDM or WRC rear housings. Anyone have any resources?

The mooresport non adjustable trailing arms are lighter if you don't need the adjustment.

the billet lateral links are also very light

Stratodesigns makes a 3kg billet rear upright (they also make fronts)

https://www.facebook.com/Stratodesign/photos_stream

The cool thing is this one uses the bolt in FRONT sti bearing. boom.

[Santiago]

Stratodesigns makes a 3kg billet rear upright (they also make fronts)

The cool thing is this one uses the bolt in FRONT sti bearing. boom.

No, the cool thing is that those are insanely SEXY! Wow...I may need some alone time now...
Wonder what they cost? Almost seems scary that they don't even advertise a price. What's that saying: "If you have to ask, you can't afford it."

Think I'm in the need-to-ask category, but it's a nice thought all the same...

On to other recommendations - the chromoly would be nice, and if were a $1K option I bet lots of folks would take it. The downside would be the increased difficulty in welding it on FFR's end and on our end the difficulty properly welding mods to it. Still, that would be a nice option to consider.

Scargo, at 3-3/8" you're not far off from a 3" design target anyway, and they made that work at WGI. I think you're safe there. I also think you can get away with 2.5" but you're now likely going to need to get serious about controlling that bump...and if you're doing that, best not to count on getting much dynamic camber gain in the process...so you need to take that into consideration when setting up the car. I'm thinking you just treat it more like a strut-based suspension - we don't get much of diddly in camber gain on them, but if you bump up your static camber the car can do well. Not sure what to make of aero-effects possibly changing this scenario though.

What's your concern with the weight distribution? Mid-engine cars are often rear biased. The set up works, even if it isn't ideal sounding on paper.

Best,
-j

[Scargo]

OK, Where do I get these Italian slippers? Slobber, slobber.:p weight: 3 Kg What does the WRX part weight?
I meant to say 2", above.

[longislandwrx]

18.4 lbs with hubs, bearing, studs. I imagine a set of billet ones could save 20+ lbs

[Scargo]

Stratodesigns makes a 3kg billet rear upright (they also make fronts)

https://www.facebook.com/Stratodesign/photos_stream The cool thing is this one uses the bolt in FRONT sti bearing. boom.
2673526736

I'm talking to Strato Design. How about a group buy? They are quoting me $3,434.50 US Dollars for a pair of rear uprights. Relatively speaking, a good value.
Machined from high-strength billet "avional" aluminum. Very light.
As I interpret it the rear uprights will fit both WRX and STi. I am asking for an explanation of how that works. Comes with stock abs sensor and 114.3 mm front stock hub (and I assume bearings). I'm waiting for a reply.

[Santiago]

Is that price quote for one, two, or all four? Does it include bearings as well or just for the uprights?
Does this mean you're no longer considering your own design?

If you're still looking into your own design and are after lightweight high-end uprights, you should look at Palatov Motorsports (http://www.palatov.com/products/suspension.html) modular GT uprights. At $750 ea ($3K for four with bearings, hubs, ARP studs, & steering arm incl, and 8 lbs ea. for full assembly), they're actually well priced for what they are and should be easy to incorporate into any clean-sheet design. It even has a Wilwood 4-piston brake package for $600 ea., which is pretty consistent with market price for those. If I was considering a totally new design, these would be on my short list:

26737

Best,
-j

[longislandwrx]

That's the price for two rears, it will fit WRX and STI because they are dimensionally the same, but the CV splines are going to be different so you will need STI axles because you are using STI hubs.

That pricing is fair but too high for my budget... spending $7000 on uprights for this frame seems silly... If your budget is 100k, I think better starting options begin to appear

At this point id also benefit more from spending that $3500 going back to racing school.

[Scargo]

That is for two of the Strato uprights with no attaching parts. I received this response from them this morning:
The uprights are provided without hubs, bearings and trailing arms bushing.
Yes, the "double fixing" is a fitting kit composed of two shims, starting from the "WRX" dimension, but If you want the uprights with the standard "STi" dimension I think will be not a problem for our production line.
At the moment I've tested the rear uprights with the FEA technology, but in the next weeks I'll test them in the first time attack race here in Italy.

I will not rush out and buy these either. I've been in communication with Dennis Palatov of Palatov Motorsports (http://www.palatov.com/products/suspension.html) and he has been very helpful so far. Seems interested and willing to get involved in the design process for customizing the upright design to suit me and (at least make recommendations for) incorporating inboard coilovers. Thanks John for that lead! Now, I need to get Jim Schenck to provide me with front suspension geometry details.

I'm also talking to HVT about a competition and street coilover setup for the car. I just bought some cool lowering camber plates from them for my coilover setup on my STi.

I can't show the recommended Palatov upright at the moment. I have to get to a different PC so I can get it to a manageable size to post.