924Board.org

Guest · Posted: Mon Jun 18, 2001 11:32 pm Post subject:

From: Al
Email: althepa@cs.com
Date: 18 Jun 2001
Time: 23:32:05

I'd like to reopen the off-list thread myself and another guy were having a few months ago about his highly modified na 924. If you're still out there, let me know.

To anyone else: while I'm looking for a good running 931 engine, I'm also going to explore the option of beefing up my early 77 924's engine. Feel free to respond on the list or directly about any recommendations for cams, bore and/or stroke kits, or anything else you'd recommend to significantly upgrade the engine's output. The budget is fairly generous.

Guest · Posted: Tue Jun 19, 2001 12:06 am Post subject:

From: larso
Email: l_porsche@hotmail.com
Date: 19 Jun 2001
Time: 00:06:08

there is a guy on rennlist that i recommend u talk to AL!
Jay is his name and he goes by the email name "badfish", he has a hot 924 the will blow the doors off 931s, I think the main thing is pistons, if you can, a 931 cyl head with these pistons, a cam definately.

Guest · Posted: Tue Jun 19, 2001 10:09 am Post subject:

From: Peter in AU
Email: Peter@planb.net.au
Date: 19 Jun 2001
Time: 10:09:10

before you throw bucket-loads of cash at the ol' N/A 924, I suggest that you get yourself an engine simulator, build a model of the 924 and then modify it on your PC.

I've just got a copy of Dyno2000 from http://www.motionsoftware.com and it's a great tool. Loaded up everything I knew or could find out about my Euro '79 N/A and it worked out that I should have around 123hp at between 5500 and 6000 rpm - not bad when Porsche quote 125hp at 5800.

I asked it to work out the maximum power by just stroking the motor to 2300cc and trying a whole range of cam profiles - this was using the standard head, no porting or big valves. Best result, 245hp. OK, they were right about the head.

Next test, back to the standard engine and head, add a rootes-type supercharger (the sort of thing I can get at the local Jap yard from a Toyota 1G-GZE motor (not the Mr2) for $450), limit boost to 10psi .. here we go (just the blower, no other mods), 175hp at 6500rpm (same as the euro 931) not a bad start. Double the speed of the blower (they "redline" at around 11000 rpm - the blowers that is) - 193hp at 5500rpm, 197f/lb of torque at 4500rpm, now we's cookin'. Add an intercooler (60% efficient) got to have a 'cooler these blowers heat the air even better than a turbo, hello, 211hp at 5500rpm, 220 f/lb at 4500 (Carrera GT territory now). Pump the boost to 15psi.. what, only 225hp at 5500 - 6000? Check the manifold pressure graph, oops we've flatlined at 28.5psi in the manifold, guess it's time for a little head work.

Next test, back to the standard engine and head, stroke to 2300cc add the same supercharger, limit boost to 10psi .. here we go, 170hp at 5800rpm, 185f/lb at 4000 (euro 931 territory). Double the speed of the blower - 194hp at 5500 and 215f/lb at 4000. Add an intercooler (60% efficient), hello, 208hp at 5000rpm 240f/lb at 4000 (Carrera GT territory now). Pump the boost to 15psi.. what, only 213hp? Check the manifold pressure graph, opps, flatlined again.

In fact I did the test with the blower while I was writing this. Took about 5 minutes to do the test and wite about it.

Now, I'm not saying "get a blower" I'm suggesting spending $40 on software to give an indication of what will work and what won't. Cheaper than buying quad throttle bodies only to find that you get the same urge from a good head job and cheaper too.

This software is a ton of fun and it seems very accurate when you take the time to give it accurate info about the engine.

Now if I can just find flow-bench numbers for the 931 head......

As always, share your experiences.

Peter in Sydney AU.

Guest · Posted: Wed Jun 20, 2001 12:31 am Post subject:

From: Peter in AU
Email: Peter@planb.net.au
Date: 20 Jun 2001
Time: 00:31:59

Oops, that should have been 145hp for the N/A not 245hp. Unfortunately I didn't accidently discover the 924 N/A holy grail.

Peterin Sydney AU

Guest · Posted: Thu Jun 21, 2001 9:57 am Post subject:

From: Vince
Email: ponzv@aol.com
Date: 21 Jun 2001
Time: 09:57:18

I think you may have been chatting with Jay Schreffler about the 924NA car. He is on this list so go to the people and car list on this site. I don't think you were talking to me although if you go to the 1977 cars look up my car for mods.
Vince

Guest · Posted: Thu Jun 21, 2001 10:18 pm Post subject:

From: Al
Email: althepa@cs.com
Date: 21 Jun 2001
Time: 22:18:36

Still haven't heard from him. Was interested in doing so because he had some very specific recommendations on pistons, cams and such...of course it remains simpler to just find a good running 931 engine...

Guest · Posted: Fri Jun 22, 2001 12:53 pm Post subject:

From: Jon McCullough
Email: apple_bit@mac.com
Date: 22 Jun 2001
Time: 12:53:20

Visit:

www.come.to/924.org

- Jon

I have done all my mods-- I would tell you the new HP figures but my bloody car still has to be dialed in better........

Guest · Posted: Sun Jun 24, 2001 12:24 am Post subject:

From: Dave
Email: Allaces591@aol.com
Date: 24 Jun 2001
Time: 00:24:51

My 1987 924S is at about 180hp still trying to get the 200+ hp mark. Im goin to try headers and a catback system. Im hoping for a 5-10 hp gain on the exhaust. After that I want to do a ignition kit. I think its called the Omni Magnium I Want to get like 3-5hp from it. I want to put a came in too but I dont know of any If you have any Ideas e-mail me or write a post back.

Porsche Fan,
Dave

Guest · Posted: Sun Jun 24, 2001 4:40 pm Post subject:

From: Rick Martinez
Email: ricomartinez@yahoo.com
Date: 24 Jun 2001
Time: 16:40:43

Peter, did you order the Desktop Dyno 2000 straight from the company you linked to? How happy are you with it? How much did it cost? What kind of PC system are you running it on and how fast is it? I have been interested in buying this myself (for the same reasons you pointed out) but don't have a good idea of how realistic it is or how much it costs. Thanks for the info.