stolarzj

Hmm, would be interesting to see if you can get more power out of a chip programmed for more octane. I'm running 93 octane in the car anyways.

BC

Do you have complete control over the fuel cells Ken? As in can you completely change the duty cycle over the entire range? Say, by 30%?

JHowell37

Not really possible. If you want more bang, you have to go with a lower octane rating. To really maximize power, you want to run with the hottest plugs and the lowest octane rating fuel your engine will tolerate. With the fairly high compression of the 928 engine, the factory chips don't allow much variation.

Remember, if the owner's manual says it OK to use the cheap ****, use the cheap **** and nothing else. Running 93 in an engine that can run fine on 87 is wasted money, and contrary to the ads, you'll likely lose a few horses.

I think Ken uses WR5DC plugs in his cars. That's two steps colder then the factory recommended WR7DC. In this area, I can't find a WR6DC much less WR5DC plugs. I use Autolite A63 plugs. They cross-reference for applications that use either the WR6DC or the WR7DC. So I'm thinking they're somewhere between the 6 and 7. Normally I use 92 octane gas. The other week, I filled up, drove about 170 miles and then topped it off with about 10 gallons of 89 to see what would happen. It didn't knock and ping at idle when hot, but I couldn't really tell if it knocked/pinged under full throttle acceleration.

I just wish we had one of those super gas stations around here that sells 5 grades of gasoline so I could get a full tank of 90 or 91.

At 5AM this morning, I passed a C5 Corvette at 110mph. He started to accelerate when he saw me roll up on him but I had the jump. I wonder if he even recognized what passed him?

danglerb

I bought sets of 5, 6, and 7 to fool with from http://www.rockauto.com

Don Carter

The stations with 5 grades of gas are just blending at the pump. You can do that yourself. They may have only 2 tanks in the ground (reg and sup), or sometimes 3 (reg, mid, & sup).

svp928

Ken, I have some 40% nitro I can experiment with-...... you got a chip for that? ! want 170mph...

where's the smiley for "smoldering heap"

Steve

PorKen

There may be a little more power available with higher octane.

I have tuned the ignition chips fairly conservatively around the torque/hp harmonic peaks, and used 89 octane to give a little safety. Right now, I record little to no knocking.

I can't just add a few degrees over the entire rpm range, as cruise is pretty maxed out. Any more, and it stumbles at low rpm, part throttle cruise. Using Super, I may be able to add some advance around the peaks, and I may be able to lean it out further at high rpms for more horsepower.


S3s are supposed to use Super, but with the stock chips, I used Regular/87 in the winter, and Plus/89 in the summer w/o problem.

To get maximum benefit from Super, you might need to dial in a few degrees of cam advance for more dynamic compression. This would probably make for higher torque numbers than hp, which is fine by me, with the 2.2 rear end, 'n all.



I was thinking about E85 the other day. There are 1 or 2 stations around here someplace.

I could probably change the fueling by 30%, but the injectors would be max'ed out at high rpm again (like they are at stock fuel pressure).

stolarzj

I'm already running WR5's in the car. With the temps down South that hit into the 100's I feel better using the 93, besides it's cheap down here. My choices around here are 87/89/93. I probably would be fine on 89, but the price difference is so little and if I go to Costco to fill up my choice is 87 or 93, so I just stick with 93.

BC

Well, the injectors would be changed. S3s have 24s right? Stick in some 32s or 36s, and possibly you'd have to readdress the entire tune. That, some different soft fuel lines, and a coated tank, and viola - a car that runs on E85. But then you are stuck. It wouldn't run on regular fuel. That's the catch.

Mike Frye

Ken, that new 'Super Tuned' chip sounds great. I only run 93 in my car so let me know if there's going to be another version to test!

Don Carter

Agreed, only Super for my car for many years (not Costco :-), see Avatar) A version tuned to super would be super, assuming there are gains to be had.

Darklands

Euro S 3 are for normal gasoline.I think I have a disadvantage with my low compression engine.;-)
Yesterday I check my tyre pressure and was a bit low. (-0,5 bar).Next week I try again!

@BrendanC

I think the use of E 85 is the wrong path.The use of LPG is simple,it has very high octane ( 110 ) and the car is real bi-fuel .The position of the fuelcell is the only disadvantage.
Here in Germany you drive the same car with LPG for 60 % of the previous expenses.

BC

Well, here, several thousand miles away, E85 is the way to go, hands down. LPG simply does not have the potential, nor the ease of use.

PorKen

E85 is worth the extra octane if you are (turbo)supercharged. NA, I can't see a reason to modify for it, unless you are a greenie. LPG makes sense over there, because of the price break.


I will be happy if the larger throttle body (80+mm) makes for sharper peak HP. Then the effects of octane, cam timing, and other tricks can be properly tested. Right now, the top end is clipped, so any 'improvements' get swallowed up by the flat torque/hp peaks.

Don Carter

Got the chips installed this evening, also replaced all the rubber fuel lines and installed a used (928 Int'l) 87 FPR. The car won't start. Fuel pressure gauge on the rail is reading 0. Quitting for tonight but any ideas of what to check tomorrow would be appreciated.

The chip install went smoothly, notches in the right orientation, didn't break or stress anything. Set the MAF to 382 Omhs while I had access to it, in preparation for Blink'r adjustment later. Can't think of anything else that would keep the fuel pump from running. Didn't remove any relays or fuses, just disconnected the battery while working on it.