Finally got car dynoed

John Smith · Dec 10, 2005

Hi,

I finally got around to getting the car dynoed. I did this in anticipation of getting a supercharger (I have never trusted my cars health) The results of the dyno were mixed: The car seemed to make the right amount of power (233HP@around 4500rpm/274TQ@around 4300rpm) So, the power looked good, but the reason we didnt run higher RPM's was because the car was running pretty lean (AFR was 14.8 pretty much the whole time) and started to ping. The HP was still going up when we let off the gas(so, it looks like this car may actually be pretty strong for a near stock car) I was told to either get the car tuned, or try running 91 octane (highest we have here in CA) I am going to run 91 for a while and see if that helps.

triggz · Dec 10, 2005

Do you have your AF graph? 14.7 is stioch which is what it should be at idle and cruising, but WAY too lean to run WOT even on an NA car.

Your AF should be 13:1 for NA, 12:1 with a power adder.

John Smith · Dec 10, 2005

I have uploaded the AFR graph. What would cause a car to run lean like this?

03ghoststang · Dec 10, 2005

get a hand held tuner like SCT or diablo so you can get that adjusted that is pretty lean for a N/A car

John Smith · Dec 10, 2005

I have a Diablo Predator (which I dont use) what should I do with it?

03ghoststang · Dec 10, 2005

get a dyno tune with it that way they'll adjust the A/F ratio and you can even advance the timing on it for a real good performance gain

John Smith · Dec 10, 2005

Well, I would get a tune except for the fact that I am going to add a supercharger within the next few months. I will of course be getting the car tuned at that point. I just dont want to pay to get it tuned twice. Can I just use the predator to add fuel. The guy who had my car on the dyno said he would add 20% more fuel if he was tuning the car.

yankcollector · Dec 10, 2005

91 octane

Don't even bother putting 91 octane in the car. The car set up for 87 and 91 won't make any difference except to waste money. I had my car dynoed also and after 2500 rpm it got real rich. A retune with a chip (diablosports) or whatever brand you decide to use is the only way to fix it permanently.

03ghoststang · Dec 10, 2005

you have to use the highest (91) or (93) octane when you have a custom tune specially if its a diablo tune or else you will ping and that will do damage to the motor if not taken care of

John Smith · Dec 10, 2005

I guess this will all get straightened out when the blower get tuned. I am just curious as to what would cause the car to run so lean.

03ghoststang · Dec 10, 2005

John Smith said:
I guess this will all get straightened out when the blower get tuned. I am just curious as to what would cause the car to run so lean.

once you start to modify the car you will require a tune to correct the A/F ratio because it would tend to go lean.. but yeah you should wait until you get blown for the dyno tune

triggz · Dec 10, 2005

If youve got a predator you can correct this yourself easily. Id go out there right now and modify the fuel tables. Add like 5% to both ranges. That wont be an accurate tune, but it will be a lot safer than what you're running now. You risk destroying it at any moment with that lean of a tune.

One reason you're making so much power is because you're running so lean. Lean = mean, but also ='s BOOM.

John Smith · Dec 10, 2005

triggz said:
If youve got a predator you can correct this yourself easily. Id go out there right now and modify the fuel tables. Add like 5% to both ranges. That wont be an accurate tune, but it will be a lot safer than what you're running now. You risk destroying it at any moment with that lean of a tune.

One reason you're making so much power is because you're running so lean. Lean = mean, but also ='s BOOM.

What exactly do I do? I assume that I modify the Factory HP Tune. Do I add 5% to both the 2000-4000 RPM WOT and the 4000-7000 RPM WOT ranges?

Thanks,

triggz · Dec 10, 2005

John Smith said:
What exactly do I do? I assume that I modify the Factory HP Tune. Do I add 5% to both the 2000-4000 RPM WOT and the 4000-7000 RPM WOT ranges?

Thanks,

Yeah thats all. Make sure you're ADDING fuel, going to the RICHER side.

Since you've got it though, you can gain another ~10lb-ft of torque by boosting the timing if you want. Thats where the big HP gain is.

If you add timing (by using the performance tune and then maxing the spark advance) i havent heard of anybody pinging on 93 with this, but you need to bring the AFR down some more to a safer level, say add 10% across the range

I'm trying to find my old dyno sheets to see exactly how much the fuel %'s increase the AFR. Itll differ slightly with each car, but I think I leaned mine out 6% to adjust from ~12:1 to 13:1. I'll get back to you on that.

sgarlic · Dec 10, 2005

John Smith said:
What exactly do I do? I assume that I modify the Factory HP Tune. Do I add 5% to both the 2000-4000 RPM WOT and the 4000-7000 RPM WOT ranges?

Thanks,

triggz said:
Add like 5% to both ranges.

Think that was answered already.

John Smith · Dec 10, 2005

sgarlic said:
Think that was answered already.

Whoops, my bad. Sorry and thanks everyone. I will mess around with the Predator tomorrow.

Thanks,

John Smith · Dec 11, 2005

I richened the car by 5%, hopefully that will be enough until I add the blower.

Thanks everyone

Finally got car dynoed

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