Imo000

Just got back from taking my '85, 5-speed with the SC to the drag strip. Wanted to see how much the SC will improve on last years 13.54sec run.

The SC set up is a very basic non intercooled system, running ~6-7psi at full boost.

As expected with the stock 225 tires, traction was an issue, ever more when the temperature dropped after 8pm.

My first run was 12.900 sec., I didn't want to push the car on the first run. Since I turned a sub 13 sec run, the track officials asked me to rent a helmet. The following runs were somewhat up and down with about 4 runs in the 12.8 sec range. As the air cooled the HP numbers started to go up but with the track cooling down and stock tires, the 1st and 2nd gear became very difficult to hook. At the end of the night my best was 12.8 sec @ 109mph. This was more than enough to beat almost all the C5 group (except a Z06, that was running 12.2sec). I raced and won against a couple of Dodge Ram SRT10s, and some '06 Mustangs too. The SRT10s are fast for a heavy truck (13.1-13.3).

To me, dropping the cluch at around 2500rpm was the ticket to a 2.00sec 60' time. I know this is not that great, but with 225s that's the best I could do.

On the way home, I let her loose entering the highway and the cold air acting like an "natural" intercooler the motor felt like a real monster.

I'm pleased with the results. 7 tents off for under $1000

DFWX

Outstanding!
I inquired at the local 1/8th track what they would require, if anything, for me to run a 928. They had no idea what that was, so I said, "it's a Porsche". The response was, "nothing, well, we suggest a jacket." But then the official saw my wife's 928 with the custom S4 body kit, wing and BBS wheels. Scratched his chin and added, "better bring a helmet."
I took that as a compliment for the appearance of her 928.
Excellent time on street tires.
Does yours have the stock transmission or an early low ratio one?
Mark

IcemanG17

Under $1K.....thats the cheapest S/C I have ever heard of!

12.8 @ 109 is a very good time...you should post it at www.dragtimes.com

John Struthers

Choice!
Great looks and good times!
If only Porsche had edged performance JUST A LITTLE toward the low end on the 79-86.5 models.
We might be seeing a lot more sHARKs on the road today.
And if the old saws: Cheaper by the dozen, and win on Sunday sales on Monday are an indicator
I don't think I'd be to far off the mark in assuming there would have been bigger and longer
production runs.

m21sniper

Nice run Imre.

Giovanni

SC for under $1000? I want one of those? Tell us more about the setup.

Imo000

I built the whole thing myself. Had a Paxton SC kit left over from my '93 Trans am. I tried re use as much as possible but ended up only using the supercharger and nothing more. My setup has the dissadvantage of having the SC in the same spot as the AC compressor. Since my AC hasn't worked in 10 years,it wasn't an issue to remove it.

I had an idea of using that space for a superchager install. Shaark89 posted pictures of his SC setup. The SC on his car was where the AC compressor used to be too, except his car is a 6.0L stoker with a Vortech SC.

I mocked it all up using a cardoard at first, then used plexigass and aluminium tubing to make a tamplate. The reason for the plexi was the ease of seeing where to drill the mounting holes.

Once I had the template ready, I scavanged an old milling machine access panel door to make the mounting bracket. the end product was a heavily reinforced mounting plate.

The pulley came off an early 90's Ford Crown Voctoria I found in the junk yard. Had the same diametre and rib numbers as the one on the Trans Am. I welded this to the original pulley and called it a day.

The FMU was Shaark89's old one, that he sold to me. The blow off valves are also salvaged units. One came off a 90s Nissan 300ZX TT, and the other from a Ford Probe GT Turbo. The "3.5 90 degree elbow at the MAF meter was from the local Mack dealer and the clamp came form the Peterbuilt dealer. All the piping was bent at the local muffler shop. Bough a 4 foot lenght of 2.5" HD rad hose at NAPA to connecte the piping .The clamps, besides at the "3.5 elbow, are regular hose clamps. The air filter is bolted right to the end of the SC and is a 6" K&N unit with a 3.5" inlet. The SC belt was also from Napa.

Without the SC and the FMU the total cost was $250 CDN (~$200 USD). The FMU was $55 incl. shipping (on E-bay they sell for about the same), and if I include the cost of a used Paxton supercharger (~$550-600), the total cost is arund $1000 USD.

The A/F gage and the boost gage is not included in this calculation, they are not essential to a basic SC kit and they wre also left overs fromthe Trans Am.

"If you can't afford to buy it, build it"

Attached is a picture of the finished product. You can see the top of the SC at the bottom left corner of the engine bay.

DFWX, the transmission and rear end is stock as far as I know.

Bill Ball

Very nice, indeed. The way you were able to find parts from whatever vehicle and make them work is an artistic talent I haven't begun to understand.

One issue I see with all of the current kits is optimal breather plumbing so that you don't get oil blown out when you get on it for extended periods (say, 50 miles). What did you do? I see plumbing, but I don't see it enough to understand how yours works. Some kind of breather hose appears plumbed into the intake tube on the driver side. That can't be right. What's that? What did you do with the vapor recovery system? At least on later cars you must disconnect that or the gas tank will inflate.

jyoon

nice times with the s/c. was the 13.45 sec stock? that seems pretty quick for stock. also, when you say dropping the clutch at 2500, do you mean letting off quickly and slipping some, or do you mean dump? i would think you would get alot of wheelspin dumping it.

Giovanni

That is very impressive, SC for a grand. You need to come up with a kit and sell it on ebay :-). Or what about a "build your own SC kit" with detailed pictures???

Imo000

Thanks Bill,

I have not resolved the oil blow by issue completely. The small catch can you see on the right bottom corner is a temporary setup. It's a the line running straight from the venturi line that was eliminated. I have two more vent lines too. One is from the "T" intake plenum and the other is installed at the top of the oil filler car (not shown in this picture). In a week or two I will make a larger catch can to accept all 3 venting lines. 2 out of 3 are running straight to the atmosphere and this is not a good setup. I realized this after I got home form the track and the driver side wheel well was covered in oil. This is not that big of an issue since the blow by is only relevant when the engine is running hard under full boost. The catch can system will be adequate for my needs.

I was not aware that the vapour recovery system will feed pressurized air onto the gas tank. Do you know where the vacuum line is located? I will install a check valve to keep the tank from pressurizing.

Imo000

Jyoon, thanks,

My avatar has a typo, it was supposed to be 13.54 and not 13.45. I noticed this just recently and haven’t had a chance to correct it.

For some odd reason my ’85 is a lot faster stock than every other ’85 I’ve heard of in a stock configuration. I did have a chip set in it to get the 13.54, but even without it the best I got was 13.7sec., that was 100% stock even the spare tire and an addition small tool box was in the car.

As far as the dropping the clutch at 2500rpm goes. That’s exactly what I meant, stepping off it at 2500. The tires would spin slightly and the car would launch fairly good (considering the tires are only 225s). The traction problem came once boost started to build.

I would have burn the clutch if I tried to slip it during the launch. I almost fried the clutch last year and that was before the SC. I was sure it burnt, I could smell it for at least half an hour after the run. The clutch felt different after this, but over time the glazed layer must have worn of and not its’ back to what it was before. I know it’s a matter of time before I have to get new disks, but for now it’s OK.

Imo000

Giovanni,

As soon as I have a little time, perhaps over the winter, I will make a site for my build. Fortunately I took lots of pictures from beginning to end. I will try to make it as simple as possible so others can either copy or use my setup for their own build. I’m not sure if any other SC besides a Paxton will work. The space constraints are a limiting factor. As long as you can find a SC that has similar dimensions as the older Paxton unit, the ”SC in place of the AC” setup will work. I know Shaaark89 has a Vortech Sc in the same place, I got some pictures to help me from him, but that’s on his 6.0L race car.

Fastest928

Bill,
I have the oil breathing solution in test now. ... it looks very good!

Marc

Imo000

Good that there will be an oil recovery and recycle system available. I know this is a very touchy subject for everyone. I've got this feeling from all the vague answers I got when I asked what the best setup was. People must be trying to make a functioning setup and then market it.

As for myself, I've just finished building an catch can large enough to make it work for my setup. It's a recovery only system and will require periodic drainage, but for the total cost of $15cdn, I can't complain. Used the left over 3.5" pipe to make a tank 17" tall with 3 seperate 1/2" inlets and one draining valve.

From research, alot of people are using modified air compressor oil removers. This works in alot of applications, except in the 928. We have much more blow by then normal.