largecar379

how many "7" liter strokers are out there?

I know there are a few 6 liter motors, but I was wondering just how many guys were venturing into the 7 liter world, and what are there current success rates?

bore and stroke configurations would be helpful as well.

(answer can be original cylinders or liners/sleeves--doesn't matter to me)


--Russ

RyanPerrella

To my knowledge only the mythical todd in GB has one, but who knows.

Jim bailey - 928 International

Zero ... running I believe. The 6.5 liter is the common size that can be built without removing the none removable cylinders and installing some other type of cylinder. That is a 104 bore + - and 95.25 mm stroke. With 5.85 "Chevy rods" .

Rick Carter

And never will until some one does it.

Mike Simard

I know it's popular to cast doubt on wet sleeved engines but ANY method is dependant on the execution. With a wet sleeved engine there are so many variables that you can't suggest the process to be flawed, at least not honestly. The process has been around, just not on 928 engines.

IcemanG17

Okay what is a "wet" sleeved motor?? I know there lots of 6-6.5L "strokers" out there...but none if any larger than that....a couple in the works, but none running yet...

Mike Simard

Maybe sleeved would be a better term, any 928 version would be 'wet'. Sleeving is when the cylinder towers are machined away and a new custom cylinder is put in. The idea in our case is to take advantage of the big-block like bore spacing in a 928, you can only overbore a stock bore so much but there's still alot of room left over between bores. My sleeved engine has a 109mm bore and there's still room for cooling in between cylinders.

hacker-pschorr

Todd has built two and a half (the 7 liter is not complete) sleeved motors.
One is in a Wisconsin owned (yellow GT from California) track car.
The other is in Todd's garage, it was pulled in favor of a somewhat stock 5.0 to use as a test motor for Autronic. Once Todd is satisfied with the Autronic system, the sleeved motor will most likely go back in. It's hard to say since he keeps coming up with new ideas to try.
If he hits 800rwhp with a "stock" based 928 motor (looking very likely), not sure what he'll do next.

His background making sleeved motors extends far beyond the 928. He started making his own cylinders for air cooled motors 10-15 years ago (maybe longer). Most of those are in race cars and have proven to be very reliable. The most impressive motor is the type IV (from a VW Bus) on his motorcycle pumping out almost 400rwhp.

Todd would agree 100% with Sterling - it's still an unproven setup on the 928.
For those of us who know Todd, he doesn't give up easily so he'll figure out any problems that arise.

Mike Simard

I understand but if my motor or Todd's works or not isn't enough data points to determine whether they "last", it will determine how the particular way we each built the engine works.
However these work you're never going to see "more than a few" running around, it's alot of work and nobody is asking for them.

V2Rocket

probably be easier (and cheaper) to swap an LS7 and SC it...

hacker-pschorr

What fun would that be?

If cheaper & easier was on the menu, we wouldn't own 928's (or any Porsche) in the first place.

hacker-pschorr

Todd made a comment it would be fun to build a N/A high compression version

I was thinking someday when I have the money to burn, that would be a cool engine to drop into the replica cobra. Imagine what that would sound like with open side pipes.

Mike Simard

Yea, you could keep the 427 badge too! There's a Cobra with a Ferrari V12 out there somewhere, ahh...
If you drop your 7L 928 engine into a kit car, how about a Beck Porsche 907(or whatever it is)? If it were rear or mid engine you could even mount Webers and not worry about them blocking your vision

largecar379

interesting responses......

now here's something else to think about:


how much "play" is there in the timing belt?

(without getting too far into my crazy thinking, what I am asking is this: if we were dealing with a timing chain, think of adding another link or two to the chain to make it longer. using this analogy, how much adjustment is there in the timing belt?)

--Russ

IcemanG17

Por-Bra

Thats on my "list" for down the road fun projects!!!

However a 7.4+L 928 NA race motor would be very nice.....imagine any of the top current strokers with an additional liter of displacement.....on Louies motor that would be over 650whp.... Of course a boosted 7.4L would be even more fun...using Todd's boosted motor as a guide that would be almost 1000whp!!!

Shoot I would be happy with 500whp!!!! Even 400whp would be nice!