O2's and Alcohol

[bigz]

What should my O2's be at WOT with alcohol. I've experimented a little bit by leaning the car out by dropping fuel pressure down and the car doesn't seem to like it. I have the power plate and just put in my Red Armstrong 108 octane chip and the car feels like it's running great with 24 lbs of boost and only four knock counts. I'll try to eliminate that by adding Xylene or dropping the boost a pound or two. My O2's are in the 820-830 range and my fuel pressure is 42 lbs line off. I know the alcohol adds fuel so is it acceptable to run a little richer with the alcohol kit. Thanks



Mike

 

[salvageV6]

Anything below 800 on pump gas and I get plenty of KR even with alky.

I would think your 820-830 number on pump gas is right on the mark.

Just my .02.

 

[Turbo__Tim]

I agree. 830 is perfect for me!

 

[GNVAIR]

I have gotten down into the 780 range on mine on Alky and 24lbs of boost with no knock. But generally the average is right around 800.

 

[Steve Wood]

just run it as lean as it will go without knock and then back off a couple of steps for margin. One man's 780 may be another's 830. No linearity in the o2 readings.

 

[Spoolinup]

Gotta go with Steve on this one, the o2 sensor is not accurate so unless you have the wide band it is a soft reference point. EGT, now we are getting somewhere.

Here is a break down of millivolt numbers and air fuel ratios

755= 13:1
780= 12.5:1
805= 12:1
830= 11.5:1

So if your stock 02 was accurate, and at WOT after 3rd gear on your run you are at 830, then at 11.5:1 your really flooding out hp and maybe torque, even though torque likes fat ratios.

The alcohol is probably not enough octane to supress the detonation at 24 psi, so keeping it fatter will do nothing for you.

Your turbo will depend on if you move on the boost or the timing.
Small turbo, less boost, kick up the timing (ta 49 to te 61)
Bigger turbo, less timing, run more boost. (te 63 and up)

Not the sacred word, just my opinion of turbo maps and inlet temps on different wheels.

 

[lrover2]

Knock at building boost

Thought I would jump in on this thread and see if anyone can help. I am running 45-psi fuel pressure and 18lbs of boost. I have the alky set to come on at 12 lbs. I have no knock if I do gradual roll ons but if I build boost at the line I get a 9.5 on the knock. If I hit it from a start I get the knock also so I guess its from a dead stop that I get the knock. What is next? More fuel pressure? I have the spray set to the highest also. Thanks for any help you guys can provide.

 

[suburban]

Irover2

Lower your turn on point, you have to find a happy medium. It's hard to have it both ways. you might even be able to turn pump speed down a little.

 

[Turbo__Tim]

lrover2 I'm not going to say that I am 100 percent right, but usally knock numbers on launch are the result of loose motor mounts, downpipes hitting, etc. Some chips )) even ignore this false knock for the first 3 seconds of WOT.

Adding higher octane to the tank, should solve this question for you. 2 gallons of toulene, added to a quarter of tank (4-5 gallons of pump fuel) will tell you all you need to know. Running this mixture should produce no reduction of knock on launch.

If it does, then yes you do have a problem. In that case maybe the timing is up too far at launch. Chip issue maybe.

Do not fail to add 2 ounces of Marvel Mystery Oil for each gallon of toulene added to the tank. Your fuel pump and checkbook will thank you.

 

[lrover2]

I will give the higher octane a try just to see because lowering the turn on point of the alky will do no good since I get the knock around 5 lbs. Thanks guys.

 

[RobR]

Originally posted by Steve Wood
just run it as lean as it will go without knock and then back off a couple of steps for margin. One man's 780 may be another's 830. No linearity in the o2 readings.

I have to agree with this. I was keeping my O2s in the 820-830 range and running around 115mph. I dropped the fuel pressure and it goes as low as 740-750 across the line. Still with no knock but the mph has increased to a best of 119.7!

I never really look at the O2s. I only look at knock. I just figured I wasn't getting any retard that I start leaning it up some.

I did raise it back up .5psi to be safe. Don't need to be on the ragged edge with pump gas/alky. I like to be on the safe side so a little fat isn't a problem for me.

Now if I could just launch this thing....

 

[lrover2]

Now if I could just launch this thing....

I am going to finally give the ET streets that have been sitting in my garage for weeks a shot. Hopefully launches wont be too difficult with them on. What kind of fuel pressure are you running?
Like I said I am at 45 line off with 50 delphi's.

 

[V6POWER]

TTA1387--What is your combo? What boost/timing are you running? Thanks.

 

[RobR]

Originally posted by Look Quick
TTA1387--What is your combo? What boost/timing are you running? Thanks.

I'm running a PT51, 50# injectors, THDP, SLP cat back exhaust, 210/205 cam. Stock intercooler and 3.27 gears.

Right now I'm running a Thrasher 92 and 100% denatured alcohol. I have a new Testa chip to try out now.

The converter won't let me launch anymore. I was getting 1.6x launches with the stock setup but now I'm usually 2.0. I have a 9/11 coming in this week to fix that

 

[V6POWER]

TTA 1387--You have a great mph with that combo and a stock IC. If you could get traction, you should be in the low 11's. Since you are using a 92 octane chip (18-20* timing?), what is your boost? Have you tried a higher timing chip?

 

[RobR]

I think the Thrasher's are 17-18*. I'm running ~22-23# of boost. I'm only guessing because it pegs the gauge, going by turns on the wastegate. Have to put that 30-30 in

So far the Thrasher is the best chip. I've tried a JL93 chip with 20* and my car didn't like it. I tried a Testa chip with 20* and it didn't like that either. The new Testa chip has less timing, so I'm hoping that'll be the ticket. The JT chip was a great chip at everything but WOT. Looking forward to the new chip to try.

FWIW, my car has never liked timing. Every chip I've tried, whether for stock injectors or 50#, has produced tons of KR except the Thrasher 92.

 

[V6POWER]

You are definately running well with only 22-23# boost with that low of timing. Hope the new chip gets you into the 120 mph.