porschevert

We did three chassis dyno runs today at CAROLINA AUTO MASTERS (Durham, NC 919-680-DYNO, owner Jeff Creech) on a stock '87 928 S4 five speed to get a baseline for comparison as improvements are made. So stay tuned. (no pun intended) Best run today was 279.5 RWHP and 282.4 lb/ft. As improvements are made, I'll detail them and report the gain (or loss) in power.

First of all will be an intake manifold/vacuum line refresh so we're sure it's running right. Most all of the parts will come from Roger Tyson at 928's R Us ( http://s287999742.e-shop.info/ ) First will be his intake manifold plenum extensions. Then probably an "X" pipe, (etc.) since they may compliment each other. I think some chip swapping might be in order after that.

The goal will be driveability, fuel economy & power. We're not trying to build a monster, just trying maximize and improve on what Porsche did over 25 years ago by applying what we know today. No super charger, no squirt, just practical and affordable 928 stuff that anybody can do.

The car we're working with has over 140,000 miles and sat for about seven years when I got it. So it's a good example of a lot of neglected S4's out there...intake and vacuum system needs refreshed, etc. so I think it'll be a good project to share with folks on FB and Rennlist.

What's NOT stock on the car right now is: GTS intake tubes, cam timing retarded 3 degrees, cat "test" pipes behind factory X pipe and NON-mandrel bent RMB. (928 Specialists...this will be replaced with a better RMB)

BTW: Jeff Creech, owner of Carolina Auto Masters in Durham, NC, is the proud new papa of an '86.5 S3!!! Even though his business deals almost entirely with GM performance cars, he's always wanted a 928! If you see him on RL, welcome him. He's got a wealth of information in his head!

SMTCapeCod

This should be very instructive and probably a great intro/101 lesson for new owners!

That seems like a familiar name...does the shop do some business tuning LS GTOs, by any chance?

rgs944

Now this is a thread I will be tuned in on. Good luck on the project and I am looking forward to updates. I am going through the same processes as you will undertake and I will be completing my project with sharktuning later this year. 280Rwhp is a good starting point. Don't forget about weight reduction in improving performance. Getting rid of the factory exhaust not only increases flow but also gets rid of a lot of dead weight. As far as chips I have not seen any evidence yet that it will do anything for the S4. Just wait to sharktune when everthing else is done. For your first project use Dwayne's garage for intake refresh help. His pictures and well worded instructions are priceless. Oh, and we also need pics and options please.

928mac

Will you be able to do a dyno run after each repair so that lost gains will be documented?

Speedtoys

Big Jeff is good people!

Tell him little Jeff (Jeff Mohler) from California says hi.

Speedtoys

Yes, Big J is into Big GM.

simos

X-over is the best and cheapest way to get more hp's. If going to headers, you should also change the rest of the exhaust to get most out of them. I wouldn't go for intake manifold extensions as there have been already some very minimal hp improvement experiences with those. The Enhanced Intake System would be better way to go. Standard S4 intake system flows enough but there is too much restrictions on it. EIS will help to decrease these restrictions and you should get better throttle response and some more torque/hp.

The chips I have used will but some more advance to ignition map and if already having cams advanced, you may face too much knocking, while engine is in high load(dyno). Advancing the cam timing will increase the dynamic compression and together with increased ignition timing it may be too much, causing engine to knock too easily. Since your cams are retarded, there shouldn't be this kind of issues with new chips.

The Sharktuning would be better way to tune the fuel and ignition maps. You can tune the maps to fit just for your engine configuration. Also, you'll get better fuel economy if tuning is done right.

Checking and perhaps replacing the ignition components(Ignition wires, distributor caps, rotors) and fuel system components(filter, injectors, pressure regulators etc.) will also be good to go through, before final tuning and next dyno.

Just my few cents, good luck with your project

-Simo-

SeanR

Ray, keep this thread going as you do improvements, it's a joy to read your updates on Facebook.

porschevert

We've done many intake refresh jobs but you're right, Dwayne does an excellent job with pics & description. I'd do all of that too if I had the time. I'm going to invest in a Sharktuner very soon.

porschevert

That's the plan if I can afford the time on Jeff's dyno!

porschevert

He IS good people! Knows his stuff too! He trusted me with his newly acquired 86.5 for a timing belt, Porkensioner, etc. so I felt quite honored!

porschevert

I was impressed with his shop and some of the hardware there! Almost all GM, with the exception of a Viper and one Ricer.

porschevert

I have a couple of extra S4 intakes but no GTS units. I may match port one of them at the heads and do a little work in the trumpet areas to clean up the flow. (Wish I had access to a flow bench!) My GM drag racing experience taught me that too clean can effect low-end torque - something that this engine can't afford to lose too much of. The reason for adding the plenum extensions (from 928's R Us) early on in the process is to document power increases for Roger Tyson.

I am also going to invest in a Sharktuner soon. I have a lot of customers waiting for it and it will come in most handy on this project.

porschevert

Thanks, Sean! Likewise!

milkman383

Heh, heh... You're not THE Little Jeff though, who had a 911 for a while until he got the Noble.

I am loving the 928 as a very cool looking daily driver. It's a great departure from the Vettes, GTO's, Camaros, G8's etc, I usually mess with.

Yes, I will be working with Ray on this project, I'll be doing some of the same stuff to my car as well.

This isn't a car I want to do a lot of work on, so anything really P-car specific will be going to Ray (like the timing belt he's already done for me). And if the motor does something bad and expensive, LS2 swap! (Purists hold your nose.)

Take it easy Little Jeff!!
-jeff