hacker-pschorr

The creator of this engine is wondering:

https://rennlist.com/forums/928-forum/303546-teaser-picture-427-cubic-inch-7-0-s4-engine-visit-to-todd-s-garage.html

He has been contacted by a few individuals who are interested in his sleeve system for a pair of 951's. The motor in his personal car has a 110mm bore – the engine in the picture was designed to achieve exactly 427 cubic inches.

Todd, the man behind this engine, does not really spend much time online - reason why I am posting this instead of him.

Thanks!

ehall

3.0 ltrs. You can go as far as 3.1, but the largest is generaly 3.0 litres. 106mm bore.

hacker-pschorr

Hey - nice quote

Does that include motors with steel cylinders?

ehall

Yes it does. There were once a few guys who would attempt 108mm on a 3.0 block, but to the best of my knowledge the didn't last long.
The 3.1 is 106mm (sleeved) with I believe an 88 mm crank from a 3.0 engine. There are a few 16 valve, 3.00 turbos running around as well. That's pretty much the pinnacle of reliable power to be had. Currently the guy who is probably doing work with the best sleeves is Chris White. He uses Darton MID sleeves. Do a search aand you'll learn a lot about this topic.

hacker-pschorr

Todd spent countless hours on the phone with Darton. The end result of these conversations is Todd making his own sleeves. IIRC they (Darton) only had the tooling up to a certain bore size - not as large as Todd wanted. This is why I started the tread. Curious to see if anyone has attempted a larger bore in a 951 than what Darton is offering.

ehall

The MID sleeves that I referenced were specifically designed, with Chris White's guidance, for the 951/944/968 platform.
The problem most run into is that @ 108, the cyclinder walls are so minimally thin that the cylinders can actually "move" under heavy load/boost.
the 108mm sleeving is something I haven't seen around the list, even discussed, in a few years.

ehall

ps. you might try Albert Broadfoot @ Broadfoot Racing, here in Jacksonville. He has a web site, and has done something like a 3.2 or 3.4ltre in the past.

hacker-pschorr

That's interesting - Todd's current motor with 110mm bore is not having any shifting issues. He's only running 15psi supercharged (I say only because I see 951's in the 20's around here). His S4 with this engine has been his daily driver all year. I think he's logged close to 5,000 miles.

M Danger

what about norwood?

evil 944t

try Scott Gomes.. He does some good sleeve work too.

hacker-pschorr

Cool, thanks guys.

I was joking around with Todd saying we should make a N/A high compression 3.5 liter out of my 944S - see what happens. I have a spare shortblock already - as long as the heads do not get damaged I wouldn't be too pissed. Just out a crapload of money!!!

Robby

Actually, Broadfoot uses a longer stroke & IIRC, w/a 106mm bore (the highest I've ever heard of from a stock 2.5L turbo block) was putting out ~3.3L... Broadfoot's crank was over 90mm long, but can't get to his website anymore to verfiy actual #.... Anyway, JME has built SEVERAL bored 968 based engines- they are already 104mm bore w/the 88mm stroke, but he bores them to 106mm for 3.1L total- of course, taking a 2.5L w/S2/968 crank & boring to 106mm would get you the same place. Chris White only goes to 104mm w/the MID's, so combined w/S2/968 crank, you'd have 3.0L. Either way, I don't know of any of Broadfoot's stroker cranks running around, so it seems that 3.1L is about the biggest most people "normally" run. Short of 5.7L V8 conversions like Tony Garcia's latest monster!!! That is UNREAL!!!

Chris White

"official" limits of the MID system –
104mm for 2.5 block
106mm for 3.0 block

I have done up to 108mm with the old dry sleeve system – but only for an NA – I wouldn’t trust that with a high boost turbo.

I believe that you are better off with slightly less displacement that is stronger – at that displacement 1 lb of boost will more than make up.1 liter!

The reason for the max dia on the MID is the size of the hole you have to put in the webbing of the block. If you start taking too much out of the webbing you will weaken the support for the sleeves.

RolexNJ

And this is why we are going to use a 3.1L in my engine too! I don't want to chane a thing with my new baby!