6 cylinder subaru boxers [Archive]

PhyrraM

02-16-2011, 03:40 AM

The chassis is basically done. So it's all a matter of how much room they already gave it. If they fit with the current design, cool--if they don't, maybe the kit can be modified a bit by the end user.

The 4 cylinders in a 1800 pound package will be nothing to sneeze at.

The newer 3.0 and 3.6 are only slightly longer than the H4s. The older 3.3 is easier to swap, but the longest.

MikeK

02-16-2011, 09:00 PM

There are guys getting 600+hp out of 4 cyl WRX motors, I had one that thought he could beat my 600+hp 2300 lb MarkII roadster, think again. But if his car weighed 1800lbs, I may have been in trouble.

Turboguy

02-17-2011, 10:53 AM

Gollum

02-17-2011, 01:00 PM

The traction advantage of the 4WD is only seen at launch and corner exit though. If they pitted their cars against each other from a 30+mph roll then the roadster has been given a big advantage.

All that being said, 600 crank HP is possible from the STI motors, but even they have broken apart at less than that. The WRX motor hardly stands a chance to reach those without been fully rebuilt with better internals. I've seen STI's destroy rods at 400 wheel HP because they decided to ignore a cylinder slightly under compression test.

You have to remember though, we're talking about a LOT of power for a tiny little engine. Reaching those powers safely requires careful, methodical thinking and selection of parts.

jdek

02-17-2011, 05:09 PM

Remember though, unless both cars had limited slip difs, they would each only have 1 drive wheel. The one with the least traction.

Bill Shaw

02-19-2011, 11:44 AM

And remember area under the curve. Most of the 4 banger dyno graphs I have seen look like Mount Everest. There's no replacement for displacement.

BrandonDrums

02-19-2011, 11:58 AM

PhyrraM

02-19-2011, 01:06 PM

As Ive mentioned in one of the other threads, Subaru 6cyl engines are less than an inch longer than the 2.0 4cyl. .7" to be exact.

Check out Perrin's h6 sti http://www.perrinperformance.com/pages/show/32

I doubt the engine compartment in the ffr kit will be so tight that one of these can't fit.

Take that with a grain of salt....

The newer H6s are the shorter ones. The newer ones are also proving to be the hardest to figure out electrically. They have coded keys, CANBUS, electronic throttles, etc... Most choose to go stand-alone to run them, which is an added expense.

The older EG33 is by far the most flexible Subaru H6 and has the easiest electronics, however, it's almost 4" longer than a comparable EJ series H4. (Because it is essentially an EJ + 2 cyls)

Flashburn

02-19-2011, 03:29 PM

Take that with a grain of salt....

The newer H6s are the shorter ones. The newer ones are also proving to be the hardest to figure out electrically. They have coded keys, CANBUS, electronic throttles, etc... Most choose to go stand-alone to run them, which is an added expense.

The older EG33 is by far the most flexible Subaru H6 and has the easiest electronics, however, it's almost 4" longer than a comparable EJ series H4. (Because it is essentially an EJ + 2 cyls)

Also, stand-alone solutions typically (always?) don't have OBDII compliance and cannot pass inspection in many states.

Gollum

02-22-2011, 02:00 PM

And remember area under the curve. Most of the 4 banger dyno graphs I have seen look like Mount Everest. There's no replacement for displacement.

Force induction always bends the rules though. My L28ET is a measly NON-Crossflow head inline 6 with only 2.8 liters. And it pumps out over 250 lbs of torque and if I had a good standalone allowing me to up the boost a little I could easily have over 300 lbs of torque, and before 3k at that!

The high reving SR, at only 2 liters can produce a 300hp curve in which it holds 90% or more of peak power for over a 2k rpm range!!! That's some uber flatness! Sure it will only have 100hp before boost kicks in full at 3k, but if you're racing there's no reason that engine would ever reach that low.

I completely agree that there's no replacement for displacement, but that being said most high cube engines aren't coming close to making the power they're capable of. What most people actually consider a "torquey" motor, is actually just a motor that's not even close to it's limits. Any engine reaching it's breathing limits going after peak HP will have a "peaky" dyno graph. A stock 5.0 motor shouldn't be thought of as a motor with lots of torque, but rather a limited top end, giving a broad HP curve.

And to bring it back to the subie engines, here's a friends dyno, which is actually a very conservative dyno known to be about a good 10% lower than most dyno's will read (car's owned by a friend that works for a WRX tuning shop that keeps numbers conservative for obvious reasons). This engine is completely stock except an aftermarket downpipe, tune, and running on E85. Stock longblock, stock turbo, stock exhaust manifold, stock CA Cat, stock muffler even.
http://i22.photobucket.com/albums/b346/Gollumandsmeagol/Photography%20Class/STIDyno.jpg

BrandonDrums

02-22-2011, 02:17 PM

Yeah, that's true. The newer ones are the shorter 6 cyl engines. Perrin is a top shop so I wouldn't expect a drop-in 6 cyl into an STI to be really straight forward for the normal guy.

However, 4'' still isn't that much longer and using one probably wouldn't be that difficult on a kit. If you re-use the stock harness you can wire one up and use a stand-alone system for engine management which isn't that big of a deal if you're serious enough to put a H6 in anyway.

We'll see how much space is in there I suppose.

PhyrraM

02-22-2011, 04:11 PM

If the older 3.3 liter H6 from the '92-'97 Subaru SVX fits, it will be the no-brainer choice for many folks. Stock it has 230HP and about the same torque. That's stock WRX power - without the turbo lag. The H6 is SMOOOOTHHH and sounds like a true exotic with a proper exhaust. It's pre-super confusing electronics (no smart keys, no disablers, no OBDII, no CANBUS).

It's only real negative is the fact it's the longest Subaru motor by 4"-5". Weight is likely close to an H4 considering the lack of turbos, intercooler and piping.

PERRNjeff

02-22-2011, 11:18 PM

Yeah, that's true. The newer ones are the shorter 6 cyl engines. Perrin is a top shop so I wouldn't expect a drop-in 6 cyl into an STI to be really straight forward for the normal guy.

I completely agree that there's no replacement for displacement, but that being said most high cube engines aren't coming close to making the power they're capable of. What most people actually consider a "torquey" motor, is actually just a motor that's not even close to it's limits. Any engine reaching it's breathing limits going after peak HP will have a "peaky" dyno graph.

There is one replacement for displacement........Boost!

MikeK

02-23-2011, 12:10 AM

Mike, if he truly had 600HP it would be no contest -- in his favour. The ability of a good 4WD system to put power down is simply amazing. With a simple rev-limiter bump a totally stock 300HP WRX STi runs 0-60 in 4 seconds flat.

At 600HP and 2300lbs your MKII -while putting up astounding numbers- is about 250HP beyond what it can efficiently use. Not to take anything away from your ride, but it is handicapped by it's basic layout - front engine, rear drive and only 2 drive wheels :(

At 600HP his Subie would be around 200HP below what it could efficiently put down.

Well he was displaying his dyno sheet at a local car show and somehow we were lumped into the same class, you know, it's a replica, or it's a tuner so it really does'nt matter anyway. Than when I got the trophy, he was pissed, Would'nt you be if your Mommy spent good money to build you a fast car and it did'nt win. So thats how the race began, he had to prove he had the better car, He hooked off the line and had a half a car on me till I hit second, from there I pulled past and just kept pulling on him. He either needs to work on his driving skills, or your wrong. This was not the first AWD, big hp tuner I have beat, and wont be the last, my car is like a tuner magnet.

Gollum

02-23-2011, 11:54 AM

If the older 3.3 liter H6 from the '92-'97 Subaru SVX fits, it will be the no-brainer choice for many folks. Stock it has 230HP and about the same torque. That's stock WRX power - without the turbo lag.

Just curious, but how many turbo cars have you actually driven? I agree that turbo lag can be the pits, but that being said I've been in plenty of turbo vehicles that I would never hesitate to take to a track, because you'll never be bellow full boost threshold in practical application. Sure, if you're cruising down the road going 40mph in 5th gear and then punch it you won't get full boost right away. But if you were smart, and down shifted to 3rd (which you'd do in a NA car ANYWAYS) then you'll be in full boost instantly.

If you've driven plenty of well setup turbo cars then fine, you can think what you think, but I'm just asking that we not let myths become fact in a quality community such as this.

All that said, I think the H6 prospect WILL be interesting. The more displacement you can start with the better.

There is one replacement for displacement........Boost!

You can always add boost to anything though, hence it's that's an unfair statement. A motor like a LS1 is cheaper than a RB, 2JZ, etc and you can still boost it! Best of both worlds.

BrandonDrums

02-23-2011, 12:13 PM

Well, the instant throttle response and flat torque curve on an N/A engine is pretty nice. Even on my 2.5 wrx 4cyl which has a fairly small turbo to flatten torque delivery and elminate the absence of power down low, there is a moment between putting your foot down and getting the power delivered that takes some getting used to.

Regardless if you're at a RPM that the turbo spools quickly with, it still takes time to get the turbo to spin that fast without some major tech in variable geometry turbos, anti-lag, mechanical assists etc. Perhaps on a bigger displacement engine there's more exhaust force to reduce that time delay when you start throwing boost at it.

In comparison, a n/a engine's power output will directly follow your foot. That makes it easier to make fine adjustments when things get hairy.

In terms of throttle pedal feel and responsiveness, there really is little replacement for displacement both for boosted and n/a applications. Power is one thing but I think the discussion here is mainly about how power is delivered, not how much...

Gollum

02-23-2011, 01:11 PM

Then for the most part I agree, it's never DIRECT power delivery, but I have to say that most people I think can get used to it. On a good system the lag should be in the range of milliseconds, not seconds like turbo systems of old.

Also remember that I believe the turbo on your 2.5 is a journal bearing, not a ball bearing, which makes a big difference. A good ball bearing turbo with a well engineered recirculation system will loose almost zero velocity between shifts.

I've seen that noticable lag even in high cube application, if the output is more than double NA application like it usually close to in small cube application. Anytime you're just going for a small 30-40% power increase the lag should be almost nonexistent.

All that said, the real problem isn't the turbo, but the way we regulate the wastegate. If you control the wastegate via propeller speed and then vent excess air via computer controlled BOV then you can have the turbo running at near full speed almost all the time. This then allows you to run a much smaller size hot size/larger compressor side without having to worry about surge. More boost with less energy input. Setups like these have been used for a long time in competitive racing. With the power of a modern standalone more people are looking into more unique setups like this which allow for better use of a turbo in racing application.

PhyrraM

02-23-2011, 03:46 PM

Just curious, but how many turbo cars have you actually driven? I agree that turbo lag can be the pits, but that being said I've been in plenty of turbo vehicles that I would never hesitate to take to a track, because you'll never be bellow full boost threshold in practical application. Sure, if you're cruising down the road going 40mph in 5th gear and then punch it you won't get full boost right away. But if you were smart, and down shifted to 3rd (which you'd do in a NA car ANYWAYS) then you'll be in full boost instantly.

If you've driven plenty of well setup turbo cars then fine, you can think what you think, but I'm just asking that we not let myths become fact in a quality community such as this.

All that said, I think the H6 prospect WILL be interesting. The more displacement you can start with the better.

You can always add boost to anything though, hence it's that's an unfair statement. A motor like a LS1 is cheaper than a RB, 2JZ, etc and you can still boost it! Best of both worlds.

My daily drivers are a '02 WRX and a '93 Legacy turbo. I also have another early Legacy turbo as a rallycross car. I am specifically looking for a street car with this kit, so my goals of little to no lag are aimed in that direction.

Flashburn

02-23-2011, 08:35 PM

To argue "my turbo 4banger is better than your NA 6 cylinder" is pointless. You can always turbo the 6 cylinder.

Please keep this on topic which is to discuss the 6 cylinder boxer options.

slopoke

02-26-2011, 11:37 AM

excuse my ignorance as Subaru is kinda new to me. How difficult woud it be to turbo the six cylinder and what kind of HP should one expect?

redsharK

02-26-2011, 11:48 AM

excuse my ignorance as Subaru is kinda new to me. How difficult woud it be to turbo the six cylinder and what kind of HP should one expect?

more then enuff to shred the wrx trans in 2wd mode...
the 4cyl can easily make 400whp with very little turbo lag
so the 6cyl with a similar config should make approx 475whp...
but in an 1800lb car, all I can say is holy crap :)
Now if transmission mods are available to support this kind of power in 2wd, then I don't see why not.

Benji

02-26-2011, 02:16 PM

more then enuff to shred the wrx trans in 2wd mode...
the 4cyl can easily make 400whp with very little turbo lag
so the 6cyl with a similar config should make approx 475whp...
but in an 1800lb car, all I can say is holy crap :)
Now if transmission mods are available to support this kind of power in 2wd, then I don't see why not.

If what people are suggesting are true, the 6sp certainly (and possibly even the 5sp) in two wheel drive on an 1800lbs car will be virtually bomb proof.

slopoke

02-27-2011, 09:48 AM

Gee ... that sounds better than a roller coaster!!! Be still my adrenalin pumpin' heart!

Gollum

03-01-2011, 01:15 AM

I want to know what tires we're all expecting to be running to blow up even the 5 speed trans in this conversion. Unless you're running a good 275 tread or more in drag slicks, I just don't see it happening. It's just speculation based off of what I've seen in WRX's, but I'd guess that for a DOT legal treadwear rating, we could see these transmissions survive 305+ treadwear with 400+hp launches.

Don't forget that in 2WD mode the gear side of the trans will be STRONGER, not weaker. And with only 1800 pounds we'll have less weight to help shock load the trans. For example, you can shred a T56 in a 3500 pound vehicle with around 800hp with enough tire, but I've seen the T56 take a heck lot more than that when it's tucked under a sub 2800 pound vehicle. Having less weight means the tires will have a harder time finding launch traction, thus there isn't the same stress on the drivetrain.

But if we'll be able to use the 6 speed tranny, all bets are off. I'll buy a specialized t-shirt for the first person to shred gears with sheer power using one of those!

Flashburn

03-04-2011, 01:47 PM

Question: Will an EG33 fit?

MDRex

03-04-2011, 02:07 PM

People have to remember that the WRX engine is build specifically for boost, while the 6cyl Subarus engines are not. Those engines will need internal upgrades to handle any decent amount of boost. Just something to consider.

BoxerFanatic

03-05-2011, 05:50 PM

I suggested/wished that there is enough room for an EG33.

If an EG33 fits, an EZ-series, EJ (even front turbo mount, perhaps), or FB series, even.

The EG33 is a 7-bearing DOHC fantastic flat 6 engine. Capable of 300+ naturally aspirated horsepower, and likely well over 400hp with a turbo or twin turbo.

I have an SVX, and a Legacy GT turbo right now... they are both great engines in their own right. The turbo 4 is a very space efficient powerhouse, but the EG33 is noticeably smoother, and healthier right off idle, even without the visceral rush at higher RPMs.

I sincerely hope an EG33 will fit, backed by a lateral drive manual transaxle. An EZ or FB will fit, then too. All great options, along with the tried and true EJ turbo.

Doc_FFR

03-08-2011, 07:23 PM

In all likelyhood the flat 6 boxer will not be part of our plan because any amount of extra space will be incorportated into the cockpit. 2-4 Inches may not seem like much but in terms of leg room it can be all the difference.

Sorry guys. Honestly I'd rather have the legroom anyhow.

Flashburn

03-08-2011, 07:58 PM

Sorry guys. Honestly I'd rather have the legroom anyhow.

Well, that probably still leaves the new 6cyl. They're less than an inch longer...

Gollum

03-08-2011, 08:43 PM

From recent information acquired, I'm not exactly sure the H6 is totally worth it. One of the big obstacles is tuning. None of the flat 6 motors came with a turbo ECU, and some of the better attempts at converting it to being turbocharged use WRX/STI ECU's and the work around for getting it to fire the other two cylinders isn't exactly well executed. Plus with the weaker NA designed internals you're looking at a full rebuild for turbocharging anyways.

The only point I can see to go with the flat 6 is if you really feel you need same HP as the WRX motor without the heat and "lag" of the turbo. But the trade off is easy HP gain potential, and possible extra cost, weight, and complexity of the build. Hardly worth it to me, but whatever floats your boat.

BoxerFanatic

03-08-2011, 10:45 PM

The EG33 was corked a bit to keep the transmissions from blowing even more than they did. The engine has more. 7 main bearings captured between the case halves, DOHC, and variable volume twin-throttle intake.

ECUtune does software upgrades for the ECU, including using Nissan Z32 Mass Air Flow sensors and larger injectors, as well as engine building services and camshaft re-grinds.
http://www.ecutune.com/

It isn't the same extent as EJ tuning, but there is some support out there. If this car new mid-engined chassis can fit an EG in it, they might be able to do a bit of business again. The SVXs are getting older, and fewer people are spending the money tuning them, as much as just keeping them going. But there is a knowledge base for that engine.

With a free-flowing exhaust the EG33 sounds like a V12, due to the even 60-degree firing order, as close to a V12 as possible with fewer pistons. The engine can sing, and is cheaper to maintain than Porsche.

I have an SVX that might be ready to give it's engine someday, but the SVX in itself is a fantastic car. I'd love to see EG33s get used for this, but I would hate to see the few remaning good SVXs taken off the road before their time. It might donate it's interior door pulls, and a few other interesting pieces, when it becomes a donor, after it is finished being road-worthy.

The EZs are more compact, and more advanced, with variable valve timing, EZ30Rs have variable valve lift as well, driven by chains, rather than belts. The cylinder pitch is shorter, so the cylinder walls are thinner, which might get into some cooling issues with turbocharging, but Perrin did try it.