928SS

building these old gals isn't exactly the cheapest or fastest way to have fun/go faster, nor for everyone - but IMO they can be a pretty cost effective all around hot rod/sports car when compared to an AMG SL65/55, Z0/C6, viper, z8, etc... (and I like the lines a lot more, not as common around socal as the other stuff and always have a sense of mystery)

90mm?? wow! course it's a 7L motor - but I'm sure something in between would help top end a bit... iirc, devek claims above 400rwhp NA it's a must have, so I think you are right

I didn't bother w/head flow stuff since I just had the bowls blended out for the larger valves, and cleaned up the exhaust ports a tad. I didn't want to lose any bottom end, so I didn't hog out the ports (guess I REALLY got what I asked for!!)

w/the AT you just can't start out at 5k rpms like you can w/a manual trans, and the slushbox does suck out a chunk of power - so I knew I wanted extra grunt for this old gal. but determining exactly now much can be had or is needed are THE key questions indeed... unfortunately, there aren't a lot of prior examples to follow, and there are a lot of different spins on strokers too - so each effort becomes a learning experience (more 928 mystery) to some extent. so I'll share what I can for anyone nuts enough to try this on their own...

fortunately, it's all pretty easy to adjust w/bolt on's at this point - but before I do much power band tuning, I want to nail down the traction issue... then I'll be better able to determine how much/if anything really needs to be changed...

in that regard, an LSD would surely help - or at least keep the tire melting more even at the strip my 1st run was over 16 sec - and a nice display of tire smoke... by gently rolling into it, and letting off a tad for 2nd, I finally managed to get it/keep it moving w/out totally wasting "the lucky tire" and too much time... it was pretty chilly out there (60f), which made the track pretty slick (according to the regulars) - so I suppose mid/low 12's would be fairly easy w/LSD, sticky tires, a warmer track - and most importantly some practice... guess we'll see what happens, go from there

my last 928 mystery was finding a pcar dealer that would make an alarm key from my VIN... finally solved that on thursday, so now my next mystery is determining why the PO disconnected the fact alarm hopefully it won't be answered w/a car fire on the 6pm news/melt something, etc - never a lack of mystery on these things

slate blue

Hi Rob really enjoyed hearing about your dragstrip fun I didn't realise you posted that time without an LSD. Now that is impressive, I hope to get to the dragstrip in the next three months and see how my mods work out. I would love to use one of those Corvette throttle bodies, they are cheap and will work with the Motec fly by wire throttle and as such can be tied into the launch control.

As to the key, becareful with that one, first you should in my opinion check if not clean all the contacts in the switches, they are gold plated BTW for good conductivity. Use some dielectric grease if you do pull it apart. Just be cautious if you car wont start or anything like that, the module has probably failed. If this is the case disconnect the battery and the system should reset itself.

As to me and my project I rhad this reponse in another thread, but it sort of got a bit O/T so I thought I would repost it here.

"I just read a Carcraft article that was very relevent to my old project and given this thread was talking about HP figures I thought I would add my 0.02 cents.

In this article there engine had the indentical bore and stroke, i.e 4.060" and 3.75" The comp was 10.88 but the engine didn't have a positive piston height which mine would have had for better quench. This engine did run on 91 octane without any trouble they thought because of the cam timing, 185 cranking psi.

Their engine used a 5.7 rod, so their rod to stroke ratio was really crappy. Not a high revver, limited to 6500 rpm.

My heads flowed better than theirs at 285 cfm versus 250 cfm but they had a bigger cam 260 degrees versus 251 degrees. Their cam had a tighter LSA at 110 V 117 of the Porsche. So a slight advantage there, mine had a slightly later closing intake valve though and both cams had indentical lifts. I think my cam is not too bad but if I had a blank sheet of paper I would probably go for a full custom job and tighten the LSA, more lift maybe but that brings in a whole new set of issues that could lead to complete castrophic failure.

When run on the dyno, max power with the coolant temp at 110 degrees F was 502 hp and at 185 degrees was 483 hp. Maybe the Porsche wouldn't be affected due to the different manifolds? Also the my dry sump is worth atleast 15 to 20 hp and add another 5% for higher comp and we come out safely at low 500 hp probably 525hp or so. That is an engine worth building! Oh, just had another look at my account, no yet, but hopefully in the future."

BTW I couldn't recommend a subscription to Carcraft high enough, it has some really interesting testing and they debunk some myths while their at it, some of those engine masters are really clever.

Cheers Greg

928SS

good info greg!! thx! gold in my 928?? guess the value just went up