high output 928
 

Hi guys ,looking for some direction. I have a son who at 17 got a 89 928 s4 (yeah I lost a bet). To date he has no tickets or accidents, it's his baby .Well right now he's attending SAM racing(school of automotive machinists)and he has an extra 928 motor
that he's using to work on.His plan is to build a high output motor but I'm not sure on a Porsche it's as easy as building a small block. Is there a good source for info to build a bigger Porsche motor?

A small block is much easier. The 928 is a split block and the crank is held in by a cradle. It's not anything that can't be done though. The biggest difference is, it is astronomically more expensive to build a high output 928 motor. To get 400hp in a 928 may cost 10x a sbc. (just a guess)

Better off building up some Chevy or Chrysler block. Many after market parts and much cheaper to do. Probably the only thing I would do on the 928 is put on one of those super chargers for maybe $5,000 or so. Plenty of write up's on doing it. But you can go out and buy a new Dodge with 702 HP, 8 speed trans. 400HP is nothing today. In the 60's, 70's, 80's it was massive power but not today.

Stroker motor
 

Check out Rennlist, several people are building Stroker motors for 928s and they are pushing 500 to 600+ hp :eek:

here is a link
http://rennlist.com/forums/928-forum/633108-what-company-best-at-building-stroker-engines-from-scratch.html

Yes - but building a good 928 stroker is a >>10K+ project even if you can do all the work yourself (??). Compared to a build on a current high volume/low cost (Chevy/Ford) engine with lots of aftermarket options it doesn't really make sense as a first major project IMO.

Alan

I only know of ONE cheap high output build (16v), a Euro hybrid motor. Euro heads, cams, and intake on a US 85/86 short block.

Things that rapidly increase costs, non Porsche pistons require plating the block with Nikasil for around $2k. Stroker cranks are $3k to %5k, custom pistons $2k, custom rods $2k.

It is possible to go to bigger bore fairly cheap if you reuse two sets of 968 pistons. You need custom rods, but don't need to Nikasil plate the block.

Greg Brown has a connection to make custom CNC cranks, so one idea I bounced around with him is to make a custom stroker crank that could use some kind of stock rods with a set of 968 pistons, but so far just talk as its still not a cheap route.

it already has a " high output motor " so no need