Options for Increasing the 3.5L Displacement

RAVC1 · Post by **RAVC1** » Sun Dec 16, 2012 11:22 am

All,

I recall few legitimate options for building a stroked 3.5L to install in our e12's. One of these involved parts from a Big6 engine that did not have a sound reputation (i.e., 3.5L to 3.7L) and I have been inactive for so many years here that I cannot recall the other option(s).

We really need a search function for the archives...

Please advise.

Thanks,

Rick

Mike W. · Post by **Mike W.** » Sun Dec 16, 2012 12:23 pm

On a cheap level, relatively speaking, you can bore to 94MM and use VW pistons. Past that maybe a crank from a E34 M5, one of the 3.6 or 3.8 monsters. With custom pistons. There was that long throw crank in a few E3s, but good luck on finding one of them. Not cheap either, but for lots of HP turbo is really the only way to go.

RAVC1 · Post by **RAVC1** » Sun Dec 16, 2012 12:45 pm

Mike,

Thanks for your response. I know nothing of the 94 mm bore & VW piston option so, I will spend the energy to familiarize myself with this method. Any M5 option is out and I suspect turbo charging is too primarily for 'cost of entry' arguments.

I have two 3.5L engines so utilizing these is the most practical route. I feel no need to get too esoteric but, I guess I'll need to add MegaSquirt LPG to the list of considerations. This would be involved but, rewarding.

Rick

Falkenberg · Post by **Falkenberg** » Mon Dec 17, 2012 11:12 am

RAVC1 wrote:Mike,
This would be involved but, rewarding.
Rick

Are you expecting a large improvement of megasquirt over e.g. motronic 1,3?
Or is the reason to move to megasquirt just because the 3.5 motronic can not adapt to larger displacements?

I'm asking because I have a megasquirt in the basement somewhere, but I never finished the conversion. Would it be worth the effort on a factory engine?

RAVC1 · Post by **RAVC1** » Mon Dec 17, 2012 9:45 pm

Falkenberg,

The reason for mentioning MegaSquirt was the potential use of an alternative fuel; LPG. If MegSquirt can accommodate this it would be worthwhile to pursue LPG. Options for end-users such as you and I to accomplish this conversion are minimal.

Rick

Odometergears · Post by **Odometergears** » Wed Feb 13, 2013 5:43 pm

First answer is big ass turbo or even a smaller one.

TCD has a simple setup. Google turbo charging dynamics
Run his system with 8-10lbs and enjoy the 100 hp increase along with improved gas mileage.

The 90mm crank out of an S38B38 M5 engine will do you right also. This will run around 2-4K

I have some connecting rods for that crank if you can find the crank. Most people who have one know the value.

Don't bother with spending money on larger TBs. You don't get the return you want for the money.