Moving The Engine Forward and Down

[Captain Ahab Jr]

Please post your good ideas here,

Did Porsche move the engine forward and down on the 911 RSR's, 934 and 935 and how did they do it?

If I wanted to do mid-mounted installation on a 911 what are the issues, ignoring bodywork clearances?

Sorry I have more questions than answers so all advice welcome,

[Flieger]

I think some of the most radical 935s may have had their engines moved a little forward and down since they had tube frames anyway. I do not think the distance was very great.

Fabcar made a mid-engine 911 special years ago. Norbert Singer writes in his book how the factory came to the logical solution that they would need to do a mid-engine 911 to compete in GT1 with McLaren in the late 90's. It was the natural progression of the speed required to win. That was the reason they did it. With the first GT1, not the carbon frame Evo, they took a 993 bodyshell and cut it off behind the driver. This became the new firewall, onto which a steel tube frame was attached which held the typical water-boxer turbo and transaxle, though this time turned around with the engine midships.

Basically, you would cut the shell in half, weld in a firewall, and bolt on your tube frame to cradle the engine and attach the rear suspension. Then you get the carbon fiber roof, fenders, tail, etc from the aftermarket and hang them on the frame. Cut some holes in a Lexan window and you are good to go.

[Captain Ahab Jr]

Originally Posted by Flieger

Norbert Singer writes in his book how the factory came to the logical solution that they would need to do a mid-engine 911 to compete in GT1 with McLaren in the late 90's. It was the natural progression of the speed required to win.

Basically, you would cut the shell in half, weld in a firewall, and bolt on your tube frame to cradle the engine and attach the rear suspension. Then you get the carbon fiber roof, fenders, tail, etc from the aftermarket and hang them on the frame. Cut some holes in a Lexan window and you are good to go.

I know the McLaren F1 design very well as my first job after graduating was to design and project engineer/manage a lot of the composite components and assemblies for both the road and race cars.

I shouldn't say this on here but we gave Porsche a bloody good thrashing all year at Le Mans in 95 before it got all silly and everyone started homologating racing cars for the road and the costs got out of control.

Your last paragraph describes very well what I would like to do.

[sc_rufctr]

I know on some 935s they got the engine lower by turning the transmission upside down.
The input shaft would be at the bottom which made the whole assembly a few inches lower. I'm guessing about 4 inches which is significant.
I've seen photos in books showing the inverted trans. It looks pretty straight forward.

It's a clever solution when you think about it.
There's no reason why you couldn't do the same but you'd have to plug the breather on top of the trans etc.

[onlycafe]

this is about as forward and down as it gets.





contact angela lane aka "laneco".
this car may still be for sale.

[Flieger]

Or a Beck 904....


I thought the inverted transaxles for the 935s was to correct the axle angularity on the very low ride heights. I did not think that there was any net displacement of the engine with regard to the road surface.

[sc_rufctr]

Originally Posted by Flieger

...
I thought the inverted transaxles for the 935s was to correct the axle angularity on the very low ride heights. I did not think that there was any net displacement of the engine with regard to the road surface.

You're right but I liked the idea because it would also give you more flexibility in engine placement.

[Flieger]

Anyone interested in this might want to contact 911 Design. 911 FPM They do a rent-a-racecar thing with some hot stuff. This car was a cabriolet, hence the chopped-top. No problem when you are doing partial tube frame and hanging carbon bodywork on it anyway.




Techtrix Motorsports also does some extreme stuff. This guy won the race, he even beat the ex-Farnbacher Loles 997RSR from 2008 in this 2009 edition of the POC Tribute to LeMans.






http://www.flickr.com/photos/max_911_fahrer/sets/72157619459994882/

[stownsen914]

Agreed that purpose of the upside down trans for the 935 was to change axle geometry for extremely lowered cars with large diameter wheels. I'm not sure if the factory also moved the engine forward, but it's certainly been done at least by aftermarket builders. You can buy a couple inches or maybe several, but the axles can wind up at extreme angles if you go too far.

One thing you might find if you do a mid-engine setup on a 911 is that the trailing arms get in the way because the engine would want to occupy that same space as the inner trailing arm mounts. Fabcar did dual A arms on their mid-engine 911.

Scott

[304065]

Why?

To win races?

FABCAR built one, so did Kevin Jeannette. Problem is, if you are really going all-out in a class that allows you to do so, why limit yourself to what the factory did?

Fabcar 993

That said, Tyson Schmidt moved the engine in Jack's car down and forward a bit. But we're not talking about the difference between rear and mid-engined, we're talking two inches.

If you're not going tubeframe, then there is much to be said by tuning on the original layout before moving the engine-- you can pick up where successful rear-engine cars left off and iterate on the proven fast solutions. . . and when you run out of dollars and speed . . . then move it.

Then again, Ruf put a Carrera engine in the Cayman so why the hell not?

[Steve@Rennsport]

Originally Posted by 304065

Tyson Schmidt moved the engine in Jack's car down and forward a bit. But we're not talking about the difference between rear and mid-engined, we're talking two inches.

Moving 540 lbs (engine & gearbox) two inches makes a very big differerence,....

[Flieger]

Bump

[RWebb]

here are some notes on Jack's car (gleaned from sources at end and converstions with Tyson):

Black Beauty II Jack Olson car – modified 1972 911 with 3.6L 964 engine (only mods are the B&B exhaust and the NBD chip); 2,389 lbs. with 243 hp at rear wheels; wt. distribution, F/R 39/61; torque tube cut and engine shifted forward 1.25” for wt. balance; very wide flares, has A/C, carpet, and some ext. trim; prepared by Tyson Schmidt (TRE Motorsports); Goal was to combine high grip of wide tired RSR type cars with nimble handling of narrower RS cars; LRX custom F. spindles, front A-arms have been lengthened by about 1 1/3 inches and mounting points have also been changed; Hamlin Fabrication R. camber boxes that modify the mounting points for non-turbo 911 pivot boxes to allow easy at-track camber and roll center adjustment (cheaper than 930 trailing arms). Also claimed to dramatically improve rear suspension geometry to decrease squat tendencies, accommodate very low ride heights but no change to toe settings. R. Bilstein coil-overs and 935 type spring plates. Tyson tied the center tunnel in with the torque tube, and added diagonal braces between the inner rockers and the center tunnel, which no doubt help as well. Excellence # 125, December 2003; and Pelican Forum threads: Excellence magazine arrived today. - Page 3 - Pelican Parts Technical BBS
BB2 -- Jack/Tyson/other Evil members - Pelican Parts Technical BBS

[RWebb]

and if none of the above is enuff...

on the C-GT Porsche used a ceramic clutch & the ability to reduce the diameter of the disc meant they could then lower the motor & trans.

So...

[Green 912]

Interesting thread. I have a 1977 911 that I cut up a little bit and rebuilt as a 73 RSR look (sort of) with a 1995 993 motor. It is right at 2000 pounds track ready wet. I plan to move the motor down a bit and forward sometime in February. I switched to coil over on all 4 corners and the T bar tube center section was removed for a G50 if I ever go much more on HP. I will weigh and take front and Rear % weights before and after and post.

[Captain Ahab Jr]

I am glad people find my question interesting and I hope the replies help other people as well as myself.

Some of the projects people have built on this forum are an absolute inspiration and I am enjoying every minute soaking it all up.

I have been lucky enough to have spent my whole working life playing a small part in designing some very fast cars and then trying to make them even faster.

I have yet to use my experience on a project car of my own and my aim is to build the best 911 my skills and budget will allow and at this point in time I am undecided about engine position.

My head says mid-mounted but my nostalgic heart says rear mounted as I want to build a car that doesn't lose to much of the magical Porsche 911 DNA.

[wesayso]

Don't miss this thread:
PVX build thread: one view from the slope
Awesome buid with altered weight distribution (among other things ;-))