Building a car from scratch...

[drewvdw]

Hi all, I'm Drew and I'm in the process of planning a car build for myself. It will be a tube chassis single seat open wheel "race" car and I'm considering a 4g63 and fwd trans mounted in the rear. I've got questions about dimensions of the engine/trans and mounts and if there is a 6 speed that will mount up to the 4g63 without having to deal with disabling awd. I'm sure this doesn't really belong in the newbie section, but probation and all...

 

[ThunderChild]

So, you're wanting to mid mount the engine, but still retain the awd?

If so, I'd look into the evo 7-9 drive train to satisfy the layout and 6 speed desire.
Is there a particular reason u want a 6 speed? You would have to do some figuring on getting the drive train to rotate the proper direction, mainly the front (or rear in your case) differential.

For cost, an awd setup from a 1g or 2g would be considerably cheaper, and the 5 speed should hold decently, depending on your power level and driving style during the race.

More info about your desired use and intentions would help.

 

[Chumpaumpalumpa]

I think he wants RWD. Evo motor with a W5m33 and bell housing adapter? The trans probably wont like being spun backwards. How about a 4G63 bolted to an Air cooled porsche 6 speed trans or maybe a MR2 or ford GT box.

 

[drewvdw]

Yes, rear wheel drive. I'm figuring it will be very light, 1500-2000 lbs with my heavy ass in it, so I'm not thinking crazy power. 350-400hp or so, well within the motor's capabilities. Car will be road raced and a weekend you for the most part. It may see some autocrosses and I will bring it to the 1/4 mile at least once, but that is not it's purpose. My main modifications will be a fuel system capable of E-85, air to water intercooler, and a twinscroll header with a quicker spoiling turbo. Possibly an intake manifold if that's a big limiting factor. I'd like to leave the engine internals alone if I can, but if I find a good built motor, I'm going to jump on it.

This won't be completed for a while as I'm still in the design stages, I just got to the engine compartment and thought "I wonder how wide it has to be". I'm going for something of a cross between a formula car and an Ariel Atom, except with a full cage.

Edit: I want to keep it longitudinally mounted as drivetrain losses are minimized by not having to change the direction of power flow. I don't know what you mean about that trans you mentioned spinning backwards, was it originally mated to a ccw rotating engine? Or does the 4g63 rotate ccw?

 

[twicks69]

The DSM 6-bolt/7-bolt is the proper orientation to be rear mounted in a stock appearing configuration with a F5M33 FWD transmission with custom CV axles, or with a modified W5M33 AWD transmission converted to FWD with a welded center diff, 45mm freeze plug where the output shaft goes, and removing the output shaft and viscous coupler.

As for turbos / power levels, you won't really need a twin scroll manifold or anything really crazy, and you could probably get away with a smaller air-to-air intercooler considering it is open-air. I would go with a smaller T3 turbo like a Garrett GTX3071R which will easily do 350-400 and upwards of 550whp in a FWD application when pushed. You can keep 2.0L and even a stock motor will handle it for quite some time; worst case, build it with a simple Eagle/Ross or Eagle/Wiseco standard length rod ~9:1 piston setup.

Regarding chassis and shift custom shift cables, Slanted J (Jon Lindquist) did a SLR chassis with a 4G63 and converted AWD trans to FWD, with custom cables and custom axles; it was an absolute blast to drive with just a stock motor and a 16G on it.

 

[drewvdw]

Honestly, I think a water to air cooler is going to be easier to plumb as there isn't much clean air available unless I go all the way to behind the front wheels. Water lines are easer to route than intercooler.

 

[drewvdw]

And thank you for the shift cable info, I was a little worried about that.

 

[ThunderChild]

I reread his first post, thought he said he wanted to KEEP the awd, but rear mount the engine.

I'd just do a 6 or 7 bolt, a-w ic, evo 8 or 9 turbo setup and use the same dimensions the front subframe has. I am doing a similar build for my mazda at some point, just a little more insane motor/trans setup.

Later today I can measure the engine/trans length of a 1g setup.

 

[steve]

I'm going for something of a cross between a formula car and an Ariel Atom, except with a full cage.

Edit: I want to keep it longitudinally mounted as drivetrain losses are minimized by not having to change the direction of power flow. I don't know what you mean about that trans you mentioned spinning backwards, was it originally mated to a ccw rotating engine? Or does the 4g63 rotate ccw?

I just recently learned about Mitsubishi's Formula Mirage series of the 90's. Think Formula Ford or Atlantic but with a 4G63. I had seen the Mitsubishi Colt F2000 Japanese GP car at Factory Mod '08 but it used a earlier Saturn R39B engine.

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Formula Mirage (Found on Facebook post) http://www.hawaiitalks.net/showthread.php?t=33456

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The problem with longitudinally mounting is always sourcing a transaxle and mating it to the engine.

The SLR chassis uses a standard transverse transaxle to avoid that problem.

 

[drewvdw]

I don't mind having a 5 speed, but if 6 speed is an option, I'd go for it. I plan to be significantly wider than those cars you posted and a bit longer. At least by appearances. I'm a big guy and I doubt I'd fit in one of them (6'3 240ish lbs). I'll have to check my drawings tonight to double check, but I believe I'm at 87" wheelbase and I don't remember width.

 

[screamineagle]

That Cool. I had no idea that the mirage series existed! That looks liek the common Porsche G50 gearbox everyone uses for mid mounting an engine.

 

[ThunderChild]

Now THAT is cool. Wouldn't mind doing a track day in one of those.

 

[Chumpaumpalumpa]

Turbo wise, you could do a big 16 and it would rip. ORrrrrr if you want to do something really cool, you could make a TS manifold with an EVO X flange and mount a TS 20G on there. @94awdcoupe Did this and has a write up thing.
Here it is: http://www.dsmtuners.com/threads/1st-twin-scroll-20g-on-dsm-evo-10-turbo.323777/

 

[pimpy rider]

rear/mid engine has been done a few times. guy on here did it with a mirage, search for it its sick!!! its big power n/a build.
im doing one in a first gen crx. longitudinal mounting wouldnt work in that car, not enough room, but mounting just the way it supposed to, it should work very well and not be too rear heavy. the bulk of the weight is about 14" forward of the rear axle center

 

[steve]

I plan to be significantly wider than those cars you posted and a bit longer. At least by appearances. I'm a big guy and I doubt I'd fit in one of them (6'3 240ish lbs).

Something more like the Superlight-Roadster then. Too bad the pictures are gone from this thread http://www.dsmtuners.com/threads/my-4g63-sl-r.376613/

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[drewvdw]

Yes, very similar in size, but looking a bit more like a formula car. Very likely I'll add front and rear aero, but I'm undecided at this point. I'll probably build provisions for it and leave it off for the first [dozen] drives.

 

[drewvdw]

Structurally, that's a very poorly designed car...note the lack of any triangulation at all and the fact that all the tubing is curved...I wouldn't take that to its limits, too unsafe.

 

[steve]

That Cool. I had no idea that the mirage series existed! That looks liek the common Porsche G50 gearbox everyone uses for mid mounting an engine.

From what the guy posted in the thread they are a Japanese copy of the Hewland Mark 8/9 using cases cast by Enkei (which are themselves based of the Volkswagen Beetle transaxles).

 

[bastarddsm]

Damn steve, that's neat. What year was that at MOD?

 

[steve]

Damn steve, that's neat. What year was that at MOD?

The Colt F2000 was at Factory Mod '08.
I think /J may have trailered the SL-R down to FMOD one year but I can't remember.
As far as I know, Mitsubishi never showed a Formula Mirage car, and I don't know it they have one.

 

[drewvdw]

I reread his first post, thought he said he wanted to KEEP the awd, but rear mount the engine.

I'd just do a 6 or 7 bolt, a-w ic, evo 8 or 9 turbo setup and use the same dimensions the front subframe has. I am doing a similar build for my mazda at some point, just a little more insane motor/trans setup.

Later today I can measure the engine/trans length of a 1g setup.

Did you get a chance to get measurements?

 

[ThunderChild]

Did you get a chance to get measurements?

i did, sorry it took so long

from balancer face to trans end plate (5th gear cover?) is almost exactly 36". from the back of the intake to the front most point of the turbo is almost exactly 24". from the lowest point on the oil pan to the top of the cam gear cover is ~27"

keep in mind, my setup is awd (trans), i have a fluidampr crank pulley, and a cyclone intake manifold. other than that the motor is externally stock for the most part.

with the evo twin scroll you might be a touch wider. the 8/9 turbo manifold needs a 2" spacer or custom manifold for the compressor cover to clear the front BS hump. id only recommend an 8 setup if you were longitudinally mounting and it was front engine. an X twin scroll would be easier to setup and package.

keep us updated on your progress, and let us know if you need anymore info!

 

[drewvdw]

Will do, it'll be a while though, I typically overengineer everything to death, so I wouldn't expect any real progress for a year or more...and money, money limits everything.

How about motor mount height relative to axle centerline? Gives me an idea of how tall the rear frame needs to be.