924Board.org

[Guest]

From: Rick MacLaren
Email: rmaclaren@globalserve.net
Date: 1/31/00
Time: 12:08:13 AM

I have a 1979 924 that has had a couple of problems nagging at me.

First is that there is a crappy 'lag' in most gears in the low rpm range. I prefer not to add Webers, because I expect to use the car daily, and I am fielding ideas for what to do to improve its performance in this area. But what I want to know before I do anything is WHY is this lag here? I ported, polished the head, and had high rpm springs put into the head, and freed up the air intake and throttle - I went to Jay's page and did some of the cheapo improvements. Does anyone know why the 924 feels so crappy in the range say 2000 to 4000 rpm? Will a cam make this problem even worse? And if I should use a cam, what grind?

Second, when I take off in first gear and try to change into second, the feel is awful. Typically the car is revving way too high and my shift time is slowed by my "worry" over slamming it into second and messing something up. Is this 'grindy' and 'choppy' feel from first to second a common 924 problem?

Thanks. Rick

[Guest]

From: Vince
Email: Ponzv@aol.com
Date: 1/31/00
Time: 11:05:06 AM

I would try to free up the exhaust so that the incoming air/gas gets in cleanly. Check the usual things such as filters, pumps, wires, etc. Try high test gas.
I had a stumble on my car 77 924 at 1800 rpms and we could move it around a bit with the changes in the exhaust. Supertrapps.
Race fuel eliminated the stumble. Engine slightly modified with carbs, cam etc.
My thoughts.

[Guest]

From: Fredrik
Email: i97lafr@itek.chalmers.se
Date: 1/31/00
Time: 1:32:15 PM

Difficult shifting from 1st to 2nd could be due to worn gearbox syncro. You can try using a gearbox oil additive to improve the situation.

Regards
Fredrik

[Guest]

From: Mike Holz
Email: mholz27530@aol.com
Date: 1/31/00
Time: 4:11:09 PM

Rick,
The problem with the head and intake is velocity. One has to be careful when porting not to remove much material or alter too much without a flowbench. Making the ports bigger tends to kill the air velocity at low speeds which will hurt torque. Plus the head and intake are known for poor flow. I would install an ignition like MSD and some headers with a decent exhaust. Also check your cat and see if it is OK (it might be plugged). Headers with longer primary pipes and the 4 to 2 to 1 design will boost torque at lower speeds while removing alittle above the torque peak. Try Redline MTL trans oil if you can this should help if your trans is in OK shape.

Mike Holz
'80 924 and '80 931

[Guest]

From: Rick MacLaren
Email: rmaclaren@iprimus.ca
Date: 2/8/00
Time: 7:43:39 PM

Hi Mike,
Ok. I have a factory exhaust header. Question: Since I just got the factory exhaust piece almost 8 months ago I am hesitant to get a header like the MSDS (I think it goes for $250 US). Will it (i.e., a new header) make that much difference over stock? Especially when I have NO cat and an enlarged exhaust pipe? Will there be enough back pressure to help things along in the low rpm range?

Second, I want to follow up and get the electronic ignition. Crane offers one too. Are they comparable to the MSD? The rationale for the Crane is it allows for everything the MSD offers for less cost. What about reliability? Are they the same in that respect or does the MSD win out as most reliable?

Thanks. Rick

[Guest]

From: Mike Holz
Email: mholz27530@aol.com
Date: 2/9/00
Time: 11:45:51 AM

Rick,
To be honest at this point don't change to a header just yet. I have seen too many conflicting reports from owners that see either some difference or none at all (from searching the net and old articles). I actually like the factory manifold to some extent. I hope your exhaust ports are smaller then the ports on the manifold, or else the flow will be "held up" by the ridge of the manifold port blocking the way (this is probably not your problem). It is hard to extract torque from a small motor like that and porsches like to be revved a little. Some aftermarket headers (i'm assuming here) probably do not have the testing behind them at least for 924's that I would like. As for the ignition, the Crane system is comparable to MSD. They both should help to make the car run smoother and are alot better then the factory system. You should get the impression of more power but don't expect alot. Depending on other mods the ignition sort of compensates to help deliver the max the engine has, plus it is hard to feel 3-5 HP. (but 3-5 HP across the intire RPM range really helps acceleration more than some bigger peak number) Did you check your timing? A little more advance helps the power in the lower part of the rpm range. Some of the newer ignitions allow you to bypass the distributor timing and allow in car tuning. I will be experimenting hopefully toward summer with this on a 931, 944S2, and possibly an '80 924. Hope this helps if not ask more!

[Guest]

From: Mike Holz
Email: mholz27530@aol.com
Date: 2/9/00
Time: 11:46:09 AM

Rick,
To be honest at this point don't change to a header just yet. I have seen too many conflicting reports from owners that see either some difference or none at all (from searching the net and old articles). I actually like the factory manifold to some extent. I hope your exhaust ports are smaller then the ports on the manifold, or else the flow will be "held up" by the ridge of the manifold port blocking the way (this is probably not your problem). It is hard to extract torque from a small motor like that and porsches like to be revved a little. Some aftermarket headers (i'm assuming here) probably do not have the testing behind them at least for 924's that I would like. As for the ignition, the Crane system is comparable to MSD. They both should help to make the car run smoother and are alot better then the factory system. You should get the impression of more power but don't expect alot. Depending on other mods the ignition sort of compensates to help deliver the max the engine has, plus it is hard to feel 3-5 HP. (but 3-5 HP across the intire RPM range really helps acceleration more than some bigger peak number) Did you check your timing? A little more advance helps the power in the lower part of the rpm range. Some of the newer ignitions allow you to bypass the distributor timing and allow in car tuning. I will be experimenting hopefully toward summer with this on a 931, 944S2, and possibly an '80 924. Hope this helps if not ask more!

[Guest]

From: Rick MacLaren
Email: rmaclaren@iprimus.ca
Date: 2/11/00
Time: 8:50:23 AM

Mike,
Thanks. It does help a lot. There is presently an MSD digital system that allows programmable control much like, I think, the Electromotive system but it retails for $1000 CDN...a little cheaper. Yet the Crane has a three stage rev limiter and three switches...each may allow a component to come on at predesignated times, like for nitrous or shift light. I suspect the MSD system will get my cash but I'm looking presently for literature from the manufacturers to compare specs IN WRITING.
I recall the guy who did the head work reworked the gaskets to fit the head, and if I recall correctly the holes at the exhaust manifold are not smaller than the ones at the head. But I can check. Hopefully the guy who did the head work wrote some of these important details down somewhere...

[Guest]

From: Vaughan Scott
Email: vscott39@hotmail.com
Date: 2/15/00
Time: 9:09:27 AM

There's one big huge item I don't even see mentioned in this thread: the kind of mods you list, Rick, are usually in the category of those which add power at the top end at the expense of torque.
This is never mentioned by the engine builders (or only by the really honest ones): it works great for a race engine which spends all it's time at high RPMs, and which can benifit from more power up there, but torque down low and streetability do suffer.
That's the inherent tradeoff.

Can't really help much, now that the work is done... though going for full header and ignition systemare recommended to maximize what you've got.

Vaughan

[Guest]

From: Rick MacLaren
Email: rmaclaren@iprimus.ca
Date: 18 Feb 2000
Time: 18:40:04

Vaughan,

I can do that. I recognise now, thanks to your post, the "top end" versus "bottom end" improvement thang...I can live with that.

The only real increase I have seen to affect bottom end seriously is the supercharger. But aside from the expense the damned things heat up so much, and stress the engine so much, that it seems I can easily waste an engine...