924martinirossi

A friend gave me 5 gallons of AVgas that he used to run in his race car. Any hidden dangers of running it in a 84N? My car is chipped and I know that it might toast the CAT. I've heard that the car will pass smog without the CAT. The person who programed the prom said the car will not pass smog and I'll have to install the orginal chip. Oh yes, the new chip ignores the OX sensor signal.

Porsche-O-Phile

AvGas is formulated to run in a low-oxygen (i.e. higher altitude) environment and IS leaded. The variety you have can be determined by color. Most likely it is a bluish color, meaning it is "standard" 100LL (low lead) avgas. Other varieties include greenish (also 100 octane), purple (115 octane) or red (80 octane). Some people claim it'll make their car run like a raped ape, but others advise caution. The lead WILL likely toast your catylitic though in either case.

Danno

DO NOT RUN AVGAS IN YOUR CAR !!! It's lower in specfic-gravity (density) than automotive gas and you'll end up running very lean on your air-fuel mixtures. Even worse if your car can't self-correct the lean mixtures based upon O2-sensor feedback. The lean mixture will cause super-hot combustion leading to detonation & knock. Youl'll end up frying your valves and/or melting your pistons. Do a search for "avgas", you'll see that there's a couple of high-end tuners who've completely destroyed their engines running the stuff.

Better deal is to use a couple gallons of toluene (114-octane) or xylene (117-octane). Both of these have higher density than auto gas, so you'll end up with a richer mixture (safer).

But either way, the exercise is moot on an NA engine. That's because HP increases come from getting more air through the engine; such as turning up the boost on a Turbo. On an NA, the only way to take advantage of higher-octane is to increase compression (around 11.0 to 12.0:1 is sweet spot). This requires taking the engine apart to install high-comp. pistons and/or shaving the head. The other much less effective way to get power from more octane is to increase the ignition-timing in the chips. Both of these methods when optimized for high-octane gasoline, precludes ever going back to lower octane pump-gas; you'll always have to run the higher-octane fuel, forever....

If you were to add high-octane gas to your car in its configuration without changing compression or igntion-advance, you'll get absolutely zero increase in power.

88BlueTSiQuest

I was hoping someone would say that. My biggest pet peave is having to wait for the high octane pump at the gas station to become clear, because some idiot is dumping high octane fuel into their Cavalier or 1985 Caprice, just because they think it's better.... Little do they know they might as well be throwing money straight down the drain, as that was 10-20 cents a gallon that they waisted.

And yes, I do require higher octane fuel in 2 of the cars in my signature, one is supercharged the other is turbocharged. The 944, when on the road, simply gets low to mid octane, as I haven't determined which is best for it yet.

Shutemup

When I was in Anniston AL last month there was a gas station that had either 101 or 110 at one of their pumps, can't remember which.

Bones944

The "super premium" pump gas will usually run cleaner and more efficiently in cars that do not require 91+ octane resulting in slightly better fuel economy, but not worth the extra coin to purchase it at today's prices.
Higher octane doesn't produce extra power, it only allows cars tuned for it (race cars running 115 for example) to run higher compression, boost etc. with reduced detonation. When I raced oval tracks I ran the track fuel (113 VP IIRC) but my motor was running 12.5:1 compression and turning 8000+ rpm. Without the race fuel I would have had extreme detonation resulting in burned valves and pistons. Love the sweet smell of race fuel though.........
I know I'll get flamed for racing on ovals, but hey this is NC, where NASCAR is king. It's also tons of fun beating and banging doors in a bullring on Friday nights under the lights. Just too damn expensive. Tires are $150 apiece and you might get 2 weeks out of 'em if your car is set-up correctly and they haven't been heat cycled too many times. If I had the backing I'd love to have a Hooters Pro-truck!

924martinirossi

If I get my car together by tonight (Saturday 19th) I bring the gas to the autocross in the morning and give it away. I will not run it in my car. BTW, After the install of the Power Prom Chip I ran 89 octane with no ill effects and put in a tank of 91 for the track days. Most of the time I just run 87 and have no problems. FRWilk (Power Prom) recommends that you start with 91 and then go down in octane rating from there.

The is a setting switch on the DME for different grades of fuel, but, I haven't yet messed with that.

For all of you that have the "idle shudder" problem I strongly recommend the prom upgrade.

I ordered the adapter board that comes with the "shudder fix" but didn't need to install it as my 84NA already had the removeable prom. I also have a DME P/N 944.618.121.04 that I can't use in an 84, unless I up grade everything.

So I need to sell/swap for parts the DME and or the 84 adapter board.

88BlueTSiQuest

Getting rid of the shudder was pretty nice. I ended up using a late DME and AFM to get rid of my shudder.

924martinirossi

I thought about doing the same as you, but, FRWilk said that he has yet to know of anyone that has done the conversion properly. That includes the wiring harness and new injectors, etc. So you say, that you just swapped in a late DME and AFM?

I installed the Weltmeister Response cam on the car today....and....WOW.....what a major big difference that makes in throttle response and a firmer pedal. I think I am going to need a neck brace very soon........unbelievable!

And yes I really like the Conquest TSI's. My former roommate had two of them. I would like to see them on the track and almost bought one myself.

88BlueTSiQuest

Yes, just the AFM and DME. After a bunch of reading, those were the only 2 items that were stated to be needed. The car wasn't running so well and was getting poor gas mileage, and due to the shudder, I decided to go the DME route first and found a good deal from someone parting out a car.

I know Wilk knows a ton about the Motronic, so maybe he knows of an issue that I don't seem to be seeing myself, but I say the car is operating just fine as it is.


Oddly enough, most of us Conquest owners are more into straightline speed, which like the 944, it really wasn't designed for. There are a few owners who track them in the sense that you mean, and with good results too. Especially if you were lucky enough to get one like mine with the optional Sport Handling Package, it added 8way adjustable struts on all 4 corners, and wider rims(16x8 fronts, 16x9 rears).