V2Rocket

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black944 turbo

very cool, can't wait to see this.

blown 944

Lol, I'll do my best to keep that from happenning

74goldtarga

Subscribed. The fun part of this forum is learning about this car but also about the car hobby in general. Sid - as you go along try to explain things in basic terms (within reason) so the uninitiated, including myself, can see what you are up to. I hope everything goes smoothly

blown 944

a little more progress.

I am waiting for the undersize main bearings so I went ahead and did some measuring using the std main bearings to cradle the crank.

It looks like I have plenty of valve to piston clearance even as a non interfereance engine. I measured .145 on the intake and .170 on the exhaust. This is measured without a head gasket and using my milled head (.050) with piston at tdc. I will be measuring my custom cam tomorrow. I doubt there will be any difference considering the lift is the same. I also measureed to see how the big valve will fit and there is plenty of room.

there is plenty of clearance on the rod ends on all directions.
The pistons clear the bottom of the block with ease.

I will be working on fitting the rings and filling the balance shaft drains tomorrow.

Here are some photos. I will add some more of teh block tomorrow..

Scott H

How much do those rods and pistons weigh compared to stock? I assume quite a bit less if you're doing away with the balance shafts?

86 951 Driver

Just about to ask about the balance shafts. Won't the the engine vibrate a ton without them?

blown 944

They are about 2/3 the weight of the factory items. I have ran w/o balance shafts in the past without really noticing much vibration. I know a couple people running without them for quite some time too. I also had this engine balanced internally so that should help. In hindsight I should have went ahead and lightened the crank a little more for higher rpm, but I think it will be fine to 7000 rpm.

If you take a look at some of the high $$ builds they are usually internally balanced without balance shafts.

This is the first one for me so we'll see.

m73m95

How much did the dry sleeving run? I like that you can run a little bigger bore, without losing strength.

blown 944

As of now I think I have around 600 invested in the block. Fortunate for me I have a family member that owns an engine machine shop so I get a discount. Speaking of bigger bore... We are going to test out boring the 2.5 block to accept a sleeve for a 105.3 piston. I happen to have a perfect set of old Chevy nitrous pistons that will work perfectly if it works out (this equals two sets )

DanaT

So you are putting that in my car, correct?

-Dana

blown 944

Sure, for around 8 grand installed.

J/k I want to test the limits first. I hope it holds up so the next one will be funded with this one. I really am looking forward to a big 16v ASAP.

FRporscheman

Hey Sid,
Thanks for answering my questions from last week. I think this is a really interesting project.

So if I get you right, the main attractions of this design are the smaller bearing areas (which are better for oiling), the addition of sleeves, and the increase in bore and stroke. A traditional 2.8 using the S2 or 968 crank would be cheaper to build, but not have the stability of what you're trying to make. Did I get that right?

I can't wait to see how it turns out. Thanks for sharing!

piperporsche180944

I can't wait to see this project done! I want a 2.8l again.....

blown 944

Actually the main attraction for me is the challenge of it all.

In regards to cost. I believe my setup will cost less than the traditional 2.8. Not having to source an 88 mm crank makes it a repeatable process easily. The cost of having a 2.5 crank fully worked is less than a core. This includes grinding, lightening, cross drilling, nitriding,and balancing. To add even a couple processed to a 3.0 crank adds a bit of money.

The other idea is that the parts are easily attained. When it comes to pistons.. For each "set" I buy, I actually have 2 sets for builds as well as rings.

Like I had mentioned earlier. Even just buying the main hard parts costs more than my whole build.

Not to mention having a sleeved block that can hold up much better. Also, being able to use a better quality race bearing inexpensively.

My only stumbling block so far has been having mains turned down. I should have researched bearing first. They are on their way from Germany...