andy-gts

Just thinking about a project...would sc 6.5l engine be way too much for the drive train and that is why no one does it OR is it the 6.5 liter monster is just way too perfect an engine for the 928?
andy

RyanPerrella

im thinking you may kill yourself before you kill the car

andy-gts

Just wondering if there is some limit to the system as to why some one hasn't done it! But I see Tom F. has a 6.0 that is sc.!

Vilhuer

Couple of problems in doing it. 968 Turbo S pistons are easily available only as 104.5mm 1st oversize. Its hard enough to find 928 block which has enough material for 104.0mm std bore size. Even with std 968 bore block wall thickness is very thin. Other than that there shouldn't be any problems in doing it. I think there was 6L SC engine done years ago already for some US track car.

Giovanni

Probably because there will be no money left for the SC after you complete the 6.5 L engine.

Vilhuer

Yes. I would build 6.5L SC instead of NA engine if it would be possible to pass yearly inspection with SC. It might take years to do it but I would do it simply because its possible.

Ispeed

What would you need a sc 6.5L for? Is the GTS that slow? I know I'm getting old...

hacker-pschorr

Yes it is

However, 500-550rwhp can be safely obtained with boost on a stock motor with a proper tune. Before jumping head first into a stroker / boost project, I suggest wringing out everything the stock motor can do and see if that is still too slow.

IMO it's all to common for people to assume they want / need more then 600rwhp when they've never experienced a 928 with over 350rwhp.

Todd is on the verge of reaching (and possibly exceeding) the 750rwhp mark with a five liter. Not only does this show how capable the stock engine is, it exposed a few issues that makes tuning a 928 at this level a bit tricky.

BC

The heads, to flow that much air, need alot of work. They become the restriction, it seems, at that power level, and not much can be done after the ports have been increased in size.

Vilhuer

No one needs stock GTS either. Even fully functioning 4.5L has more hp than anyone could need in normal car. Its just question of wanting something which is totally irrational. It doesn't matter that its unusable or way too expensive.

BC

Its... Its like we're... Brothers! Long lost brothers!

Jim bailey - 928 International

The stroker engines tend to have a very high compression ratio (the long stroke jambs more volume into the same combustion chamber area) which limits the amount of boost that they can tolerate. Start lowering cutting on the piston and the squish area is affected. I think many people have a lot of trouble conceptualizing how air moves simply because you can not see it and it is everywhere ! Fuel injectors we all know flow more fuel by opening longer OR we can increase the pressure and the same pulse delivers more fuel ! Normal air pressure is one BAR about 14.5 lbs that is what pushes air into the cylinder add more pressure and the same valve opening is going to flow more air just as a fuel injector flows more fuel. The point being increased pressure is going to cause more flow which can overcome less than ideal intake design , runner length length , port size , valve size , and cam lift and duration.

RicerSchnitzzle

But this one goes to eleven....

IcemanG17

I think the largest 928 motor that is currently boosted is Tom F's big bird 6.0L stroker with a Vortech style SC...... I don't know how much power it makes though?

BC

There will be a 7L with boost very soon. (not me)