Has anyone built a 5.4L for the street using a 968 pistons and stock stroke crank? Dyno results? This would be for a 89 S4 with 5 speed.

I just bought a second set of 968 pistons and have thoughts of using them with a second block I had bored in a street 928. I am not sure it is worth considering since I would need custom rods anyways, so it might not make sense to do this without using a stroked crank as well. Of course perhaps stock S4 heads are sufficient for a 5.4L when they aren't sufficient for a 6.4L motor.

 

why buy 968 pistons unless they were dirt cheap. They are huge, probably weigh 50% more then a newer design JE piston would weigh and they arent forged, just simply pressure cast. I thought the 968 pistons are far past their sell by date technology wise? Or am i wrong?

I guess if you already had 4 and needed another 4 for the set then you should get them or sell the 4 you did have, 4 pistons for a 928 owner is totally useless no matter what they were. But I just thought there are allot better ways to go then 968 pistons at this point in time.

 

Both Louie and myself have "new" stroker motors using 968 pistons.
Guess we just like old proven technology.

 

Did anybody actually get the JE pistons to work even a few hundred miles?

 

Ryan,

I meant a set of 8. I already had a set of 8. So now 1 set for the race car motor build and 1 set for the street car motor build

They may be old technology, but they are known to work in 928 blocks that are simply bored and lapped. I don't need to be an expert in metallurgy or in installing cylinder sleeves to know they will work. Since the solution I am going for is a known to produce 500rwhp, it will be just fine for me

 

Sterling, i doubt anyone has 100K on any stroker with any set-up in all honesty. I think those engines get refreshed too often for other reasons.

Mark, I am glad you didnt take my question about 968 pistons the wrong way. I was kinda asking, not trying to sound like I knew they were no good or anything. I dont know honestly, but I had thought there were much better pistons available then the 968 units. Being that those pistons went into a block of the same metallic properties in the 968, it seems that there wouldnt be any expansion issues or anything that you may have with a forged piston from JE.

 

lindsey racing says they have 12,000 miles of hard boost runing on JE pistons (wiseco actually, but they will use JE now) and Swaintech coating on the skirts in an ALUSIL bore.

 

968 pistons are forged, not cast.....BTW.

Stan, I built such an engine as you describe for a '91 GT that had ruined bores from a manifold that got powder coated and not completely cleaned. The power increase was not very significant, just about what you would expect from increasing the displacement from 5.0 to 5.4 liters. That is what we expected would happen, without any other changes to the engine.

 

Ok, thanks Greg. I guess I will have to plan on a full stroker motor for the street too

 

Dosent Mahle use a pressure casting for all their piston blank's. Perhaps the 968 pistons are manufactured another way but when i was looking into 911 pistons and cylinders mahle was always the way to go but I remember that they were pressure cast, (they claim its nearly as strong as a forging) but that's how they made those pistons. I assumed they made all their pistons the same way.

 

Sounds good to me.

If you are going to be a bear.....be a grizzly.

 

i am not trying to contradict you Greg, relax. Like i said I had thought Mahle used a pressure casting for all their pistons unless they are racing duty or some extreme application. But as i also said i could be wrong. I dont claim to know everything.

 

Ryan, looks like he didn't see your post and was replying to Stan...

 

I remember seeing a 5sp S4 back at Devek days a while back...02 or 03...had everything stock except the bores were 104. dyno sheet was posted on the window..330 hp..330 ft-lbs at rear wheel dynojet...
Wasn't that impressive at the time I thought for all that work..but imagine some big valves.(968)..and GT cams..would certainly help..and if you added Louie's Ind. Throttle bodies I bet that those numbers would go up ..and rev like a banshee... ...

Later,
Tom
89GT

 

Thanks Tom