How low can the Subie boxer moter be mounted for the ultimate low CG?

[Cooluser23]

Some rough measurements for starters:
http://www.locostbuilders.co.uk/gallery/engine1text.jpg

Perspective view:
http://www.locostbuilders.co.uk/gallery/WRX041.jpg

Of course the engine can be mounted a whole lot lower in the vehicle by using a low profile oil pan. This will help lower the center of gravity, as well as possible ground clearance in case people want to rally the 818 on uneven pavement, or a dirt road.

Stock
http://www.blabberon.com/images/oilpan2.jpg

Low Profile
http://www.blabberon.com/images/oilpan7.jpg
http://www.blabberon.com/oilpan.html

Other vendors
http://www.ravspeconline.com/shop/catalog/images/subaruoilpanhighvolkitlow_199_general.jpg
http://2.bp.blogspot.com/_VxodNA843wM/SZocbf60AjI/AAAAAAAAAIc/fAvtHqW8YV4/s320/oilpans.jpg

[Cooluser23]

An "accusump" may be helpful for aggressive cornering in case there is issues with the low profile oil pans. I'm hoping Subie owners can chime in.
http://www.accusump.com/images/MarineAccusump.jpg
http://i15.photobucket.com/albums/a358/Yannis440/twin%20turbo%207mgte/accusump007.jpg
http://www.accusump.com/

Or even "dry sump" conversions for the ultimate in lowering the CG.
http://thmotorsports.net/images/stories/PRODUCTREVIEWS/2010/MAY/ejds-cosworth%20dry%20sump.jpg
Product review Cosworth Dry Sump setup Subaru EJ (http://www.thmotorsports.net/product-reviews/23-product-reviews/1690-cosworth-dry-sump-setup-subaru-ej.html)

I'm getting really curious what FFR has in mind for mounting the engine and the SLA suspension setup. This thing should handle great. :cool:

[LifeIsOnTheWire]

my guess is FFR will be engineering this thing to use the stock WRX oilpan.

if it turns out as such, and you want to go dry sump, and lower the engine, fabbing up new mounts is fairly elementary.

[thebeerbaron]

Of course lowering the engine from the default 818 location would change the angles at the CV joints... Hope you planned accordingly.

Sure lower is better, but does it make a meaningful improvement? Depends on the user.

[olpro]

Doesn't this engine already have a very low cg compared to others? What is the point of jeopardizing the geometry for some tiny marginal gain?

[PhyrraM]

The bottom of the flywheel is already within a few inches of the bottom of the pan. So any gains can only be marginal.

That being said...
If FFR uses the stock front CV shafts, I cannot see 2"-3" of verticle displacement being a problem. Subaru has played with rideheights before (Legacy>Outback) which is functionally the same as lowering the transmission.

[16g-95gsx]

I've done testing in the past with various CV angles and saw almost no power drop off, with even very severe angles. This was on a dedicated engine dyno test.

[Cooluser23]

my guess is FFR will be engineering this thing to use the stock WRX oilpan.

if it turns out as such, and you want to go dry sump, and lower the engine, fabbing up new mounts is fairly elementary.


Of course lowering the engine from the default 818 location would change the angles at the CV joints... Hope you planned accordingly.

Sure lower is better, but does it make a meaningful improvement? Depends on the user.


Doesn't this engine already have a very low cg compared to others? What is the point of jeopardizing the geometry for some tiny marginal gain?

Part of the reason I want an 818, rather than some homebrew tube-chassis car is because I have faith that the suspension geometry set by Factory Five will be PERFECT and optimized for handling and ride quality. That's the beauty of a scratch build car. The way I understood the FFR 818 project is that the car was designed around a perfect SLA (double wishbone) suspension, with a chassis built around it.

I don't want to lower ride height, or anything like that, since the body should be designed around the suspension, and the body can be lowered for optimum ride height, while leaving the suspension at it's optimum.

If factory five designs the suspension around a lower profile oil pan, they can match the rest of the geometry to that. They may even have the option of designing the chassis with different suspension attachment points, depending on which height the engine is mounted. (to give people the option of using flatter oil pans, or even dry sump systems.)

As an example the chassis could allow for different engine mount points, to set the engine at different ride heights, should users want a full depth oil pan.

[Cooluser23]

I've done testing in the past with various CV angles and saw almost no power drop off, with even very severe angles. This was on a dedicated engine dyno test.

Could you go a little bit into detail about that? Do you have sketches/pictures? How extreme of and angle did you try? Did you move the engine further back for better handling in the Subie?

[LifeIsOnTheWire]

i'm sorry but I would have to disagree with you. I would prefer FFR design the kit around the stock WRX engine (and stock oilpan).

that makes for the best compatability for everyone. if they were to require a certain 'xyz' aftermarket oilpan for the kit, that will only create headaches for people who want to use alternative motors (EZ30R, or even the new upcoming Subaru flat-4 engine, which BTW, Subaru has confirmed will be the same outer dimentions, and mounts to create maximum compatibility.)

[thebeerbaron]

The way I understood the FFR 818 project is that the car was designed around a perfect SLA (double wishbone) suspension, with a chassis built around it.

I too expect the 818 to have a wonderful suspension, but (and please take this in a friendly way) you've got to stop obsessing over SLA/double-wishbone. First off, the suspension is stated to be SLA/multi-link, not pure SLA. Secondly, you do realize that there are drawbacks to an SLA suspension, right? In the case of the 818, one distinct disadvantage is that using double-wishbones on the rear hub carriers would mean not reusing perfectly serviceable donor parts, even if it could be done, which I'm not sure is possible. (I am NOT a suspension designer!). I hate to come across as a jerk, but repeating something incorrect as fact is not really helpful here :)

[Cooluser23]

You're right. ;) No worries, you don't come off as a jerk. I do obsess over it a bit too much. I guess I'm just tired of strut type suspensions, where aggressive camber angles chew through the inside edge of tires like there is no tomorrow.

http://www.youtube.com/watch?v=ftf3KYHTOYU
I think this video illustrates this well.
I guess mistakenly I use the term SLA as a generic term to include multilink designs, opposing to a McPhaerson strut setup - My bad.
Obviously rear suspensions tend to include a trailing arm/link to help turn/steer the tire under load.

I'm not a suspension designer myself by any means. - I'm still learning as well. I do however understand the disadvantages about certain setups used on OE type suspensions on mass produced cars. While struts have the advantage of being cheap/few moving parts/less alignment necessary at production/less components (i.e.: ball joints) to wear out/etc. - They do have a huge disadvantage of tire wear, which for a hobby track day driver like me, add up high running/maintenance costs.

Another design advantage of multi-link/double A-arm/SLA rear suspension, in combination with a flat boxer motor is the possibility of a trunk/storage above the engine similar to a Porsche Cayman setup. Having huge strut towers in the back would limit that.

I fully trust FFR to not skimp on the handling on any of their cars, and to design a great suspension, which will make both "Canyon carvers", as well as track day enthusiasts, happy. They have the experience and expertise to know which parts to reuse from the donor, and which parts to design from scratch, utilizing as many stock components (like hubs, etc.) from the donor car.

I'm sure that once the design is closer to being finalized, the FFR team will chime in and educate us on the "how" and "why's" of their design direction.

After all, they're much better chassis/suspension designers than most of us will ever be. (the GTM can put many "exotics" in their place.)

I think the reason we're all so passionate about all these aspects of the 818 is because we really enjoy cars and driving/racing. It's good to disagree about some aspects. There is no one right way.

What we have in common is that we don't want to end up with a "boulevard cruiser" that looks the part, but can't perform. (not to say, that I wouldn't enjoy a nice looking 818 that I can park in front of 4-star hotels or the opera. - knowing the valets will leave the car out front, parked next to expensive exotics, the likes of Ferrari, Lamborghini, Lotus, Aston Martin. :cool: :p )

[PhyrraM]

Don't forget that struts are also very strong. WRC level cars use struts. I will admit I don't know if that's by choice or by rule, but the fact remains that they DO use them. As posted somewhere else on these forums - Rally cars with proper suspension setup and tires can approach F1 speeds around a certain tracks.

Also, in the design of the suspension, a strut is designed and treated like a SLA with a length of zero for the top arm. Race cars with very controlled roll rates, roll centers, and suspension movements can have very few issues with struts. However, street cars that need realistic comfort variables in regards to roll rates, roll centers and suspension travel, need the extra control provided by SLA/multilink suspensions.

Adapting a strut knuckle to use an upper control arm is a non-issue for a company like FFR.
http://farm6.static.flickr.com/5028/5670600753_f2a496516d_z.jpg (http://www.flickr.com/photos/23291496@N04/5670600753/)

[Scubynubie]

Just remember that the exhaust manifold bolts to the underside of the heads, and comes down almost as far as the oil pan...

http://www.flatironstuning.com/images/Product/large/1878.jpg