912 race car cams, how wild is wild nuff

snowman · 08:51 PM

I have a 66 912 race car. I built the engine using everything that is the best, eg Carillo rods, latest Scat crank, Shasta Pistons, all the tricks, and an Elgin M7805 Cam at 312 deg duration. Puts over 145hp ON THE GROUND in dyno testing. That means about 180 to 200 HP at the crank. Not bad for a 1720cc 50 year old engine.

I am not satisfied, so I personally bought and turned out a cam blank out of 8620 steel. I sent it to a well known cam grinder to make the ultimate race cam for a 912. Before this I had contacted most of the cam grinders for such a grind, but it turns out they do not have any suitable blanks in stock, consequently I had ot roll my own. I am still discussing the specs for this cam with the cam grinder.

So whats your dream cam grind?? Duration, lobe centers, lift and whatever. I hope to get the most ever achieved out of any 912, to race it a couple of times, and then sell it to someone who can win with it. I am hoping for over 160HP on the ground, ie a 912 engine that can beat any 911S engine of that period hands down.

I have run a computer sim of the stock 912 engine, the current race engine using dyno 2000 and actual measured air flows and parameters. The sim agrees with the stock engine hp and the race engine hp within 2% or so. I have not been able to out do the 7805 cam in any simulation. Is the sim not accurate or am I on a mission to nowhere? What I am looking for ammounts to 230hp at the crank at 8000rpm. Intake system flows 190cfm at 0.55" lift. compression is 12.5 to 1, headers are stepped, large tube, red line 30wt race oil, 90lbs min pressure, Datsun 42mm intakes. intake stacks 110 percent of displacement and length resonates at 7800rpm, record type grooves cut in entire intake system, coated everything.. Valves swirl polished, full 5 angle cuts on everything., necked down valve stems. Everything cc ed and matched, balanced to withing 1 gram, special honing of cylinders. All tolerances within 0.0005" of desired, cylinders honed with special torque plates attached.

svandamme · svandamme's Garage

180-200 out of a 1.7 liter engine??

that's 105/117 hp per liter

not wild enough ?!?!? it's better volumetric efficience then the 906 carrera...

how often do you want to rebuild that engine?

Jim Richards · 03-15-2006, 06:06 AM

why is this on the OT forum?

masraum · 03-15-2006, 06:44 AM

Hmm, I remember your post about having too many cars. I think you should send me the '66 and the '69 which should help make room for the mini AND help with this cam question. I could live with the measley output of the engine in its current form.

snowman · 03-15-2006, 04:12 PM

Quote:

Originally posted by svandamme
180-200 out of a 1.7 liter engine??

that's 105/117 hp per liter

not wild enough ?!?!? it's better volumetric efficience then the 906 carrera...

how often do you want to rebuild that engine?

No more than once every 3 track sessions.

Jared at Pelican Parts · 03-15-2006, 05:03 PM

what the hell are you complaining about?

I WISH my old 914 was putting out that kind of power

id10t · 03-16-2006, 05:16 AM

I don't think you can get that kind of horsepower and go 3 seaons on a single build.

Why not put in a medium-hot Typ 4 engine ?

svandamme · svandamme's Garage

Quote:

Originally posted by id10t
I don't think you can get that kind of horsepower and go 3 seaons on a single build.

there are more then 3 sessions in a season i would think
he said sessions... so i would think multiple rebuilds per season

widebody911 · widebody911's Garage

Sell me the 912 engine and put a type IV in there.

deathpunk dan · 03-16-2006, 05:55 AM

yeah
raby is now building 220+ hp STREET type 4 motors for those with the wallets. I can only imagine what he can do with a race motor.

snowman · 03:25 PM

Its probably in the range of a $20k motor now, I am just trying to get a little more, cause more is good. I could always put a chevy engine in it, but there are some things you just don't do to a Porsche.

The VE is about 107% from 5000 to 7000 rpm. I think 110% can be had and to run it to 8000 rpm where it can make more power.
As to someone doing better, I doubt anyone else has spent the time to flow every individual part, optimize it, re flow test it, and then flow every single part from intake horn all the way to exhaust pipe when all connected togather and re optimize it for even better flow. at least on a single engine. Then theres the custom cam design to match the actual measured flow rates. several thousand hours here alone. I probably only gained 5 hp over the best out there, but more is better.