87 Carrera power increase

I have an '87 Targa. I am looking to increase the horsepower in the most cost effective manner possible. In other words, my wife won't let me spend much! I've already put a K&N air filter on. Is the next step a chip? Has anybody had much success with these? I've heard that a SS exhaust system will add 20hp, but I can't afford the $1000 price tag. Any other suggestions?

Hey there, I would recommend an Auothority chip and then an exhaust. The chip will increase your power significantly. If you're really on a budget, get a cat-bypass pipe. These modifications should make you happy, (for a little while). Have fun!

Mike

I'm not too impressed with either the chip or the exhaust changes...been there, done that. I believe that Porsche did an excellent job on the stock chip and the exhaust system.

However, I found significant and cost effective performance improvements which I have done on my '86 Carrera:
1)Had my air flow meter adjusted and tuned to my engine.
2)Replaced my injectors with Bosch disc type (deposit resistant) injectors from a GM 3800 engine.
3)Increased my fuel pressure from 29psi to 47psi using the Bosch fuel pressure regulator off the same 3800 fuel rail.

Since I have been running this combination for the last few months I noticed my engine stopped smoking on start up in the morning (could be just a coincident) and it seems to be running cooler. At least on these cool days we've been having recently, I noticed my front oil cooler would stay stone cold even after driving for an hour or so which is quite unusual for my car. And gas milage runs between 23 to 28mpg which is pretty amazing considering how quick it feels.

Aside from being cost effective, I really like the fact that these modifications are invisible. Everthing appears stock, from the injectors to the air cleaner. Forgive me, but the K&N air filter looks a bit tacky for my taste.

If anyone is interested in trying this out, I'm thinking about putting together a kit for about $500.

Joe

Joe, I have dyno tested the chip on my 86 Carrera and I have jumped from 188 rear wheel hp to 202 rear wheel hp. I consider that a big gain considering the addition of 20% hp loss by measuring at the wheels makes an aproximate 17 hp difference at the flywheel. This was a very noticable improvement while driving the car. I am interested in your suggestions, however you don't mention what kind of hp gain this will give. Are you talking about a 1992-1997 Buick/Olds Injectors? If this is indeed a big improvement in power it is great seeing how these parts are relatively cheap.

Mike, dyno testing was not a priority for me. What I was looking for was better throttle response, more bottom end, elimination of tip in stumble, and generally better driveability which I got. What this means for me in the real world is that I can cruise down the street at 30mph in 5th gear at 1000rpm without any problems, take off in second gear with ease and when I punch it...it goes.

The injectors I'm using are from a vin C 3800 engine which appeared in 1988 to 1995.

Unfortunately, injectors alone will not be effective without a fair amount of work to the air flow meter which is critical. And to make things worse, I don't know anyone else out there doing this kind of work to air flow meters with any success.

Joe

Joe, Dyno results directly affect the way the car feels. I agree that the main priority is how the car feels, however more power on the dyno ata certain RPM range directly affects tha feel of the car. Anyway, bout the air flow meter bussiness, I don't see what "work" can be done to it aside from adjusting the flap tension, miture and position of the potentiometer. It is a fairly simple metering device which sends signals of voltage to the computer depending on the amount of air entering through it. I don't see what could be done besides richen or lean out the mixture...

Mike, you're absolutly right about all the obvious adjustments that can be made on the AFM. In addition to spring tension and pointer position I have uncovered an area in the AFM where I found the most performance gain and that was in the bypass air.

The trick here is to get as much bypass air flowing as possible. What I did was back off the screw 12 turns, port both the inlet and outlet orifices of the bypass air, and file the air cleaner to match the ported orifice where the AFM bolts onto it.

Using that as a base line, I set the mixture with spring tension and pointer position.

I found that this not only works quite well with the stock injectors but even better with the 3800 injectors and fuel pressure regulator.

I hope you can duplicate this on your own 86 Carrera and perhaps get a little more out of it.

Joe

By the way, my 86 came with the 87 control unit. Which one do you have?

[This message has been edited by stlrj (edited 12-05-1999).]

Thanks for the info, I look forward to messing with that this spring and I'll get back to you about my results. you mention you have the 1987 control unit and I now remember that when I ordered my chip I had to give my computer # and the guy told me that it's an 87 #. Do you have any idea why?
Talk to you later. E-mail; miker76@sympatico.ca.

Mike,

I am no longer recommending the 3800 injectors that we talked about earlier but instead recommend using your stock system with a few modifications.

My latest strategy that works even better begins with spark plugs gapped at .060". I hate recommending spark plug brands beause it always becomes such an emotional issue. So with that being said, the plugs I use are Autolite 64 and not because they are any better than Bosch or NGK, but because the heat range worked so well for me.

Next, I removed the injectors on my 86 Carrera and sprayed the tips with Gumout carburator cleaner, put them in a ziplock bag to soak overnight, gave them another squirt the next morning before putting them back on. My reason for going to this trouble was to
make certain that I would not have any drivability problems due to clogged injectors and to increase my chances of obtaining a more uniform flow rate and spray pattern.

Finally, I worked on the air flow meter. The trick here is to get as much by-pass air flowing around the barn door of the air fow meter as possible. This was accomplished by using a round file to port both the inlet and the outlet orifices of the by-pass air passage. In addition, carefull attention was made in order to match the ported inlet orifice of the air flow meter with the air cleaner where the AFM bolts up to the air cleaner. So more filing was done on the air cleaner as well.

The aluminum plug which conceals the CO adjustment screw must be drilled out so you can adjust it with a 3mm allen by turning it all the way in to seat, then backing it off 12 complete turns.

The benefits of doing this, in addition to better gas mileage(29mpg), are better throttle response, lower engine temperatures, more low end torque, smoother running, and improved drivability, meaning that I can
even cruise in 5th gear at 1200rpm without a problem. Top end performance was not affected either. It runs as strong as ever, not to mention a significant improvement in my oil consumption...but that gets into another subject.

I am hoping and assuming that these modifications will also have the same results on your car. However this is based on work done on my late production 86 Carrera
which came equiped with an 87 control unit, so I am fairly confident that these results would also apply to any late 3.2 Carrera as well.

Joe Garcia
Redwood PCA since 1976


[This message has been edited by stlrj (edited 01-11-2000).]

I never understood why Porsche used that barn door style AFM. Volvo for years have been using the hot wire type, which offcourse is not restricive,and is made by Bosch.Could you modify a Volvo AFM to work on a Porsche? Would that be easier and more effective than modifying the barn door type? I have an 87' Carerra and thought about one day converting mine to the "hot wire" but the aftermarket kit costs $2000 and is stopping me for now!

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The only way you could adapt a Volvo hot wire mass air flow sensor to your Carrera would require a translator to convert the digital signal from tha Volvo sensor to an analog signal which the Carrera could recognize.

I heard of an outfit that makes such a device but I wonder how cost effective it would be.

The only reason I can think of for why Porsche went with the barn door system was cost...the bean counters won again.

Besides, if you had one of those fancy hot wire or hot film sensors on your Carrera you wouldn't have an air flow meter that you could tweek.

One more thing, Huntley Racing has a hot wire system for $1100.

Joe Garcia
Redwood PCA since 1976

[This message has been edited by stlrj (edited 01-12-2000).]