Dumb Question - Race Gas + Vram?

rpollock · 06-02-2008, 08:57 AM

This may be the proverbial throwing money down a well, but is there any benefit to blending race gas with pump gas in a vram? Other than it smells nice?

The car is almost exclusively driven on the track and readily available pump gas is 91 octane. Engine is a stock euro vram obd1. Custom exhaust.

Can the engine management system take advantage of the higher octane? Say about 95-96?

I would expect the gains to be almost negligible, if any, but I defer to the greater minds here!

Tom W · Tom W's Garage

The engine management doesn't care about the octane (unless it has been programmed for it). The car should do just fine with normal pump gas and the race gas would most likely simply be a waste of money.

I ran my 993 on normal pump gas without issue and did some tests that showed no hp difference between 92 octane and 96 otane. My current car is programmed for race gas only.

rpollock · 06-02-2008, 02:29 PM

Thats what I was thinking Tom. Interestingly my Toyota Forerunner has a rating of (I think) 240hp with 91 octane and 230(?)hp with 87 octane. Granted this is 2004 engine, and probably has a more sophisticated engine management system than the 96 vram. I also notice that my BMW 330 will throw a check engine light if you dare try and slip some 87 otane through the system! Buggers! Just thought the vram may have been able to take advantage of the higher octane without a reprogram of the chip.
Rick

Quote:

Originally Posted by Tom W

The engine management doesn't care about the octane (unless it has been programmed for it). The car should do just fine with normal pump gas and the race gas would most likely simply be a waste of money.

I ran my 993 on normal pump gas without issue and did some tests that showed no hp difference between 92 octane and 96 otane. My current car is programmed for race gas only.

Tom W · Tom W's Garage

With really bad gas, the nock sensors will detect a problem and retard the ignition (less power). So, in a way the race gas could help but it isn't likely to be better than standard premium gas.

VRAM just means that it changes intake air behavior at wide open throttle. You have the ECU from a '95 to control your 3.6? You could get a chip burned to try and improve performance (and require race gas).

rpollock · 06-02-2008, 04:15 PM

Quote:

Originally Posted by Tom W

VRAM just means that it changes intake air behavior at wide open throttle. You have the ECU from a '95 to control your 3.6? You could get a chip burned to try and improve performance (and require race gas).

The Euro Vram's were OBD1 in 96 as far as I know. I was hoping to avoid burning a chip specific to race gas. Sounds like I would have to go that route to realize any tangible gains.

petevb · 06-02-2008, 07:48 PM

Quote:

Originally Posted by rpollock

The Euro Vram's were OBD1 in 96 as far as I know. I was hoping to avoid burning a chip specific to race gas. Sounds like I would have to go that route to realize any tangible gains.

I burned 2 chips for my modified VRam- 100 and ~93 octane. There was roughly a 9 hp difference on the dyno between them. I agree that you'd need to burn chips to see significant gains on anything other than something like an extreemly hot day where you are finding the detonation limit on pump gas.

rpollock · 06-03-2008, 01:10 PM

Quote:

Originally Posted by petevb

I burned 2 chips for my modified VRam- 100 and ~93 octane. There was roughly a 9 hp difference on the dyno between them. I agree that you'd need to burn chips to see significant gains on anything other than something like an extreemly hot day where you are finding the detonation limit on pump gas.

How hard is it to switch the chips in/out?

petevb · 06-03-2008, 01:43 PM

Quote:

Originally Posted by rpollock

How hard is it to switch the chips in/out?

Not too bad, but you don't want to do it too often. I suspect the connector isn't designed for too many insertions. The idea is more to run on 100 all the time and have the other as backup. The better new systems allow you change maps with a flip of the switch on the dash. Not sure if that's avalable for the 993 yet, but it's the way to go if possible.

rpollock · 06-03-2008, 01:59 PM

Quote:

Originally Posted by petevb

Not too bad, but you don't want to do it too often. I suspect the connector isn't designed for too many insertions. The idea is more to run on 100 all the time and have the other as backup. The better new systems allow you change maps with a flip of the switch on the dash. Not sure if that's avalable for the 993 yet, but it's the way to go if possible.

I thought I read about that 2 position chip on Pelican a while back. Great idea. I'll do some searching.

kojo911 · 06-03-2008, 02:36 PM

The only thing I would add is that the 91 octane gas is just barely tolerable in a 993 motor. If you add heat (heat soak) your propensity to pre detonate (ping) will go up, some times so much so that the knock sensors will not keep up. I run a blend of 91 and 96 octane gas at the track for the extra insurance. I'm sure the motor doesn't make anymore power but it doesn't ping. Cheap insurance, my $.02