edmonton_oiler16
New member
Is it possible to get your car tuned to accept a lower octane? If there is what are the different ways?
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Tuning for lower octane
- Thread starter edmonton_oiler16
- Start date
Nitro_Alltrac
New member
It would be very difficult to tune the car to run on lower octane. The problem is going to be compression and cylinder pressure. As you spool the turbo up and build boost, you are raising the pressure in the cylinder and also the temperature. The higher the octane, the more resistant the fuel is to detonation. The only way that I can think of to be able to safely run lower octane would be to limit your boost to less than 5 lbs and even that maybe too much.
As long as the know sensor is working correctly, the ECU will pull timing and do what it can to eliminate the detonation but it isn't meant to do it all the time.
As long as the know sensor is working correctly, the ECU will pull timing and do what it can to eliminate the detonation but it isn't meant to do it all the time.
Nitro_Alltrac
New member
On 91, I would think that you would probably be OK as long as the knock sensor is good, the intercooler is working as it should and the ignition and cooling systems are up to par.
I was thinking that he was wanting to go down to 87 or 89 octane. That would be a serious issue I would think. If you can't get 92 or higher fuel, how about using an octane booster? With 91 and a booster, you should be OK.
I was thinking that he was wanting to go down to 87 or 89 octane. That would be a serious issue I would think. If you can't get 92 or higher fuel, how about using an octane booster? With 91 and a booster, you should be OK.
RedCelicaTRD
Moderator
The main reason the high octane is needed is the high timing advance under boost. You can lower the base timing but then you loose efficiency out of boost. If you had an MSD control box you could add a boost timing master, but the cost of those units combined is getting into the price of a simple standalone.
edmonton_oiler16
New member
ohh well i heard that those octane boosters dont work at all....
edmonton_oiler16
New member
would you replace the water to air one with a ata one?
Nitro_Alltrac
New member
You can use toluene (sp?). There are a couple of posts about using it for an octane booster.
No its probably alright as long as the pump definitely works and the lines etc are not clogged up with crap. If it has had a coolant change in its life it should be ok. They tend to form a brown liquid with chunks after a long time :smokes:edmonton_oiler16":axvwtgzb said:would you replace the water to air one with a ata one?
On Alltracs and octane....
Back around 2000 when gas first shot up I decided to test case my 90 on 85 oct in the cooler months. Stock boost, opened up exhaust. Elevation 7000 ft. Ran great with no audible det for 50k(most people are unaware that lower oct burns faster, its just more unstable than 91). Eventually I could just pick up some light detonation at lower RPM boost transition. Where it went from closed loop to open loop, maybe. Once it went to pig rich on the fueling maps, det would cease. If I kept revs high enough with a lower load on engine no det at all. What I think happened is this. Piston tops and combustion chamber got all carboned up. From age, less detergents in cheaper gas, or previous owner never driving it hard combined with the 70% clogged primary cat that I later gutted, I'll never know. I do know car is still running at 170k.
Point is this. All cars have varying octane tolerance especially as they approach 15-20 yrs.
Back around 2000 when gas first shot up I decided to test case my 90 on 85 oct in the cooler months. Stock boost, opened up exhaust. Elevation 7000 ft. Ran great with no audible det for 50k(most people are unaware that lower oct burns faster, its just more unstable than 91). Eventually I could just pick up some light detonation at lower RPM boost transition. Where it went from closed loop to open loop, maybe. Once it went to pig rich on the fueling maps, det would cease. If I kept revs high enough with a lower load on engine no det at all. What I think happened is this. Piston tops and combustion chamber got all carboned up. From age, less detergents in cheaper gas, or previous owner never driving it hard combined with the 70% clogged primary cat that I later gutted, I'll never know. I do know car is still running at 170k.
Point is this. All cars have varying octane tolerance especially as they approach 15-20 yrs.
Celi-GT4":2qkim5to said:Can you get e 85 in that region? If you can try swapping in some 550 injectors and running that. You will not detonate and pick up 20 free ft/lbs. I love the stuff
Have you upgraded your fuel system for that? Wouldn't he be risking corrosion issues with his fuel lines and system?
edmonton_oiler16
New member
found a place in town with 93 hopefully this will do.