Jim bailey - 928 International

Mark's engine and Joseph's are similar BUT lots of small differences .... Joe's is a nickasiled block ,Joe has a bit more displacement , both run the carbon fiber "dual" throttle body intake from 928 Developments ......

rob rossitto

remember- joe and mark are running a CF intake, and much more aggressive heads/cams at around .040" over (lots of good specs on marks car in the latest 928 forum mag), no cats, pure race car/dry sump, etc ... think joe's numbers were around 517rwhp, IIRC... IIRC, the threshie intake made about 65rwhp or so for them... a nice gain/looks really cool/ and not cheap at around $4k, but not too many options for reliable/big NA power gains though...

IIRC, joe used a nicom block and mark used alusil - joe's rev'd a bit quicker/maybe due to less rotating mass and less friction... but probably not a big deal when pushing a 3000 lb car... left some impressive driveway rubber with a set of race tires though...cool, hehehe, rubber, hehehehe..

I've got gt cams w/a .020" or so over grind, and was told to expect around 450ft lbs of torque, and around 400-425rwhp... think elgin said these cams will pull from 3-6.5k... figured the extra cubic inches(or is it litres?) would provide plenty of lower end grunt, so it would work out... going out for balancing now... hope the extra light wt (436g/piston, 600g/rod) will keep the metal costs down - hear that stuff is pretty pricey... FWIW, I'll post dyno stuff whenever it gets running/tuned... should be entertaining...

ps: pistons sold...guess another stroker monster is under construction...

Fastest928

We managed to get 500 rwhp at 6000 rpm using the stock intake, B1 cams, big valve heads and motec FI, approx 470 rwhp without motec.

Adding the DEVEK/Ott intake added another 50 rwhp.

I beleive that ~500 rwhp street legal 6.5 l Strokers will be on the road next year....yeehah!!

Regards,
Marc

blau928

Hey Marc,

Does your B1 cam have any overlap...?

Thanks,

Fastest928

.....at what lift? For all practical purposes, it is minimal and depending on tuning and cam timing, it will support a sub 1000 rpm idle.

Marc

slate blue

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.

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.

Cheers Greg

TAREK

Don't mean to be contradicting, but clearly the folks in the Mathematics department at MIT haven't resolved the issue, otherwise we wouldn't be mentioning it here.

Now computers can do anything they want in any language or mathematical model they wish. How exactly does clock speed affect the size of the bolt on the exhaust manifold? I sure would hope that comparing or even relating numbers in the binary system to numbers in the digital world is not something that comes out of ANY Mathematics department...and certainly not at MIT. Computers DON'T work with fractions, though they look like fractions to you. Besides, the folks in in the rest of the world use fractions where needed...and I think they have computers too.

Very costly to small businesses? OH MY !!!! you mean the mom and pop shop around the corner would lose business by carrying metric hardware used on more than 90% of engineered machinery of the world? Do you think a small business buys an SAE jig once and never replaces it when broken or when in need for maintenance, upkeep, and calibration?

I work in small and medium volume manufacturing, and believe me much headach and cost would be spared if we all converted to metric.

It's ironic that the bulk of the manufacturing in this country relies on outsourcing lower level components from countries where metric standards would be cheaper...yet we insist on paying the higher cost of SAE standards.

A good measure would be to test if any of the CAD software vendors would remain in business by supporting SAE dimensioning exclusively.

As for sense, yea it makes a lot of sense that the next size up from 3/16 is 1/4, when in fact it's misleading, because it could be 5/16, or 11/32, or 23/64....oh wait there is no such thing...or is there? because what if that was the largest possible size bolt that can be used for securing a critical system on the shuttle to Mars? so where does it end? Most Joe Shmoes don't know why the fractions are in that order. They just know the order in which things came in their toolsets.

Metric is incremental...too difficult and costly to track...sure

Again, I'm not trying to contradict you personally....just thought I'd share the perspective of someone frustrated with the subject on daily basis