QuikStuf993

I have a 74 911 with a 3.0 based engine modified to 3.2....it has the original cams and it has the 3.0 induction system, SSI headers, Phase 9 mufflers. This is a track only car that I TT with PCA and race with SCCA and PRC. I am at 235 hp on the engine dyno and looking to increase that significantly without going to extremes. To that order, I am coinsidering either carbs or Motec. I would like to hear anyones experience with either of those two systems, including potential costs. Due to some class restrictions with PRC I may not be able to re cam the engine. What do you all think about either system?
Thanks in advance for your thoughts and advise.

fusionsport

Motec is the answer for your track car, and as it happens we are currently putting together a drop-on MOTEC package using either the oem intake(ported) or throttle bodies. Give 3R- Racing a call and we will make this as painless as possible. Website- <a href="http://3r-racing.com/home.htm" target="_blank">http://3r-racing.com/home.htm</a>

We are also doing a MOTEC set-up for a destroked 3.6 running as a 3.3 for use in SCCA GT-2, and have some good insight into cam/head/intake/exhaust packaging for these engines

Chris Campbell

No firsthand experience, but from everything I've heard/read, the 3.0 CIS engine is seriously limited by its "mild" cams and pistons. Just switching to $1500-3000 carbs or even an $8000 Motec setup is not likely to gain much power by itself...

Steve Weiner-Rennsport Systems

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by QuikStuf993:
<strong>I have a 74 911 with a 3.0 based engine modified to 3.2....it has the original cams and it has the 3.0 induction system, SSI headers, Phase 9 mufflers. This is a track only car that I TT with PCA and race with SCCA and PRC. I am at 235 hp on the engine dyno and looking to increase that significantly without going to extremes. To that order, I am coinsidering either carbs or Motec. I would like to hear anyones experience with either of those two systems, including potential costs. Due to some class restrictions with PRC I may not be able to re cam the engine. What do you all think about either system?
Thanks in advance for your thoughts and advise.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Hi:

If you are not able to make some wholesale changes inside your engine; cams, pistons, etc, I think adding a MoTec engine management system is an expensive case of overkill, at this time. Its very good stuff, but not cheap unless you do a whole host of other things to take advantge of its capabilities. Typically, MoTec'ed race engines have extensive headwork, high-compression pistons, twin-ignition, and many internal modifications for power & durability. These sorts of configurations make MoTec an excellent, albeit expensive choice.

Adding the costs of all the hardware, both electronic and mechanical, as well as the requisite man-hours of dyno time to map your car, the costs will be FAR higher than bolting on a set of 46mm PMO carbs and doing some minor jetting.

The best bang-for-the-buck will be the carbs, in your case.

fusionsport

Steve is correct- just adding MoTeC will not magically produce horsepower, but a cam change, efi, and headwork will work wonders. Not to mention a piston/cyl swap
The thing about just bolting on carbs is they will be adequate now, but when you change your motor they become the liability, whereas efi will grow with the motor and changes better than carbs. The other things is that efi will increase power availability over carbs measurably, and that can lower laptimes.I do not care what anyone tries to tell you- efi will always produce a better power curve over carbs, and the power curve is what gets you out of corners. If you plan on not making changes to the engine, carbs are a good lower cost solution- however if you plan on gradually upgrading then at some point I would strongly recommend an efi of some sort- either MoTeC or DTA.

QuikStuf993

Thanks all, this is what I thought. Steve Weiner, thanks for the always good feedback. I do have a number of upgrades already in place from the last rebuild, but it will still take a bit more than just slapping on EFI.....there are already new cylinders and high compression Mahle with Carillo Rods and Racewear bolts, Jerry Woods springs and retainers, so it would appear that bolting in a Motec or similar system, with TMW throttle boies would require at least a top end port and polish, the twin plugs, cam, and perhaps valves. I'm hoping that properly set up carbs, a port and plish and perhaps cams might net a smoother power band and will provide the 15-20hp I'm seeking at this time. Motec may be something to do when building an entirely new engine next year.

Luice73

I'm working on my 81SC and have headers and dual exhaust... No heater (live in south florida) The engine was pulled and and all seals, clutch oil coolers and suspension were either replaced or fixed with stock parts. In my mind I thought I would be able to light up the tires (91 turbo's) but she just bits and takes off. The low end is pretty sluggish but once she gets past 3500rpm takes of like a bat. Is that typical performance for this car? The top end is crazy too... I had her up to 145 with more to go. What would be the logical next step for engine improvement? PMO's and Cams is what I'm thinking but not if I'm tuning them all the time. I want to drive my car but not get smoked by Mini Coopers and Honda Civics. Help this Rookie please.

tsheehan

Cams and 46mm PMO's . Its a slipery slope You may just stuff a 3.6 w/cams 50mm pmo's and clewit twin plug controller unit. Then you have lots of power cheepest way. You start trying to hop up a 3 litter without building a 50 hr motor you spend almost as much and you dont get near the drivable power. a high rev 3litter makes snot but they are still flat on the low end of the rpm range. You can spend 12k on the right heads to make power. Just freshen and stuff a 3.6. done sleeper. The only thing you can make smoke with a stock 3 litter is a clutch.

Regards
Tom

Steve Weiner-Rennsport Systems

The VERY first question I ask my customers who ask those same questions is; "What your budget,...how much are you will to spend?"

This, after all, is what frames whats possible to do so you get the best bang for the bucks.

earlyapex

A typical carb'd, 3.0 L spec 911 motor make about 240 hp on an engine dyno.

AussieRacer

Motec and Autronic both make awesome ECU's.

I was told that Autronic was set up by one of the original founders of Motec. They run the Autronic units on a number of racecars here in Australia. Some info on them is here ...

http://www.autronic.com.au/

- Rob

Geoffrey

"I was told that Autronic was set up by one of the original founders of Motec."

That is like saying that Porsche and VW are the same thing because the founders worked together long ago. Last I checked, the US Autronic dealership has collapsed and the distributor in New Zeland stopped supporting them. I had significant problems with the software and firmware on their newest ECU, and the ECUs look like they were put together in a high school shop class. Its not that hard to control and engine, even a Carburator can do a fairly good job. It is all of the other items that makes an ECU a good choice or not.