UncleNick

Final result 270.4 RWHP(corrected) and 298 RWTQ(corrected) Not bad for now.....got a few more things to do before supercharger goes in. I will install others "things" and do another dyno run next week. This is what it is for now. Not too bad at all!

IS_Dude

I'm guessing you're on the bottle... Be carefull dude. those a/f ratios are wayyyyy lean. I actually don't think they are even acurate. Under full throttle even a stock IS is richer than that. Only closed loop cruising are they 14.7 and some partial throttle stuff. You need more fuel and in a bad way from the look of those a/f's.

UncleNick

Yes, lean is right. We even up'ed the fuel to a 36. I have to get a 38/40 and all will be good.I was running a 30! We ran out of time this evening for more dyno tuning, but I'll be back for more tuning next week. If you look at those a/f numbers, see the 268 hp run? See how he let off around 4000 rmp because it was lean. Then we put a 33 fuel jet in and wen't up a little, then we did a 36 jet for fuel and we got 270 hp. I am going to go to a 38 of 40 fuel. I'm hoping for 300 RWHP before supercharger goes in! Hats off and thanks to guys/gals at TPS!!!

IS_Dude

is the person doing the dyno run going full throttle? 100% throttle? That's the only way to get it into open loop and start dumping some fuel. If you are juicing and your a/f ratios are higher than 13 you WILL blow your motor. not if, but when. If you boost w/out going full throttle it will go stupid lean.

I'm still not convinced those numbers are accurate and correct. I'd guess you would of blown your motor if they were that lean.

not bagging on you, i'm just looking out for you. Your a/f should be around 12:1. Anything over 13:1 is scarry unless you really know what's going on.

Turbo'd_Wxman

IS_Dude, you are right on here. A/F's of 18:1 for over 1000 rpms are discustingly lean and he must have had detonation after that run if he was in 4th gear. If I were you, I would pull those plugs and have a look at them and hope there is not engine damage. Be very careful with nitrous on our car. The massive torque increase has already blown motors and trannies on our car. If you don't back off, I think you are going to be another statistic. 100+ shot on the IS300 is a BAD idea and asking for trouble. If you are S/C'ing and spraying on that car, I doubt your car will last more than a few months.

UncleNick

So you guys are saying the higher the number, the more chance of engine failure? I thought the lower the air/fiel mix...the worse off it was? Now I am confused

Letsride

The higher the ratio the leaner you are running. Running lean = New engine soon!!

IS_Dude

First, thanks for the help Wxman.

Second, UncleNick you should definately read up before something bad happens. If you don't understand what is good and what is bad then there will be expensive days in the not so distant future. I'm actually wondering what might of happened running the car that lean while spraying. At the minimum you were getting spark knock and the engine was retarding the hell out of the timing. I hope that was the only problem.

When spraying a IS you should only do this under full throttle and above 3000rpm's. Unless you know what you are doing and running a standalone management system, which you aren't, where you can control fuel at low rpms. The stock IS computer while in closed loop is going to stay at 14.7 and if you sprayed while it was like this it would go lean and potentially cause serious problems, which is what happened. Hopefully there was no damage.

You should lay off the juice until you're able to get to a tuner that is very knowlegable. I'm not sure where you're located, but if you post your location maybe I'll know of someone.

Turbo'd_Wxman

The A/F or air fuel ratio tells you how much air there per fuel volume. Therefore, a 12:1 air fuel ratio means you have 12 parts air per 1 part fuel. The lower the air fuel ratio, the more fuel you are adding and the more rich you are tuning the car. The higher the A/F ratio the more air you are adding to the car causing it to run leaner. When you add to much air you will end up with detonation. This is when the piston compresses the air and heats to the point that the fuel will instantaneously ignite before the spark plug fires. This is destructive to the engine. If you are running 18:1 with nitrous you WILL have detonation. Hopefully there is no damage or the damage is minimum. Check with any of us here and we will help you in any way we can. Just be careful my friend.