tune question

[Bestangyet 07]

Just wondering what you guys think my car should be putting down on a dynojet. I had the car dyno tested today and I must admit I was pretty disappointed with the results. It had a nice safe A/F ratio at 11.5, but the numbers were low. It only did 420 hp, and 401 tq. I expected better even though I have only seen 113 mph trap speeds out of the car. The temp in the shop was 84 degrees, but my iat only hit 110 peak so heat soak wasn't an issue. I am running a 3.2 pulley and i thought the car would produce at least 460 to 480 rwhp. Any input would be great. Mods are in my sig.....

 

[Brenspeed]

Do you have any other modifications on the car? How many lbs of boost are you seeing with the 3.2 pulley? Also, what belt part number are you running with that pulley? Should be a 061075 belt. How much timing did the car run when it was on the dyno?

 

[b00stedgt]

4.10's will lower your numbers

 

[Brenspeed]

4.10's will lower your numbers

This is correct as well, and so will being at 7000+ft.

 

[Bestangyet 07]

Mods are in my signature where you found the DA # of 7003 ft. That is not the altitude here, we are at 4200 ft. The car has always been a little slower than I expected. My best trap speeds are 113 no matter the conditions. There were other cars at this dyno day that did very well for their mods and I was just expecting better numbers as was the shop owner. He was telling me I should do way better, and was sure there was more power there. All I got was an A/F as they did not hook up anything else but the tach leads. I hope 4.10s don't affect it that much. I am seeing 10.5 lbs. I don't think the belt is slipping, but I don't know the part # right off hand. I will check it and get back with that info.

 

[Brenspeed]

There are a LOT of variables that come into play. DA, Altitude, did the car run the timing, octane of fuel (91 kills power as timing is everything in a blower car), 4.10s do kill power but we are talking 10rwhp tops, ambient temperature, etc.. The best way to diagnose is if he were to datalog the car on the dyno while he is doing the runs.

 

[Bestangyet 07]

It was a local "dyno day", so we did not get the one on one deal. Run conditions were 84.98 degrees F., 25.85 in. Hg, 19% humidity. If this is correct that makes the DA 11724 ft. BAD AIR! It just didn't affect the other cars the same. His custom tunes are quite pricey at the paltry sum of 350 so I am hesitant to pull the trigger on one. I need to get the datalog done for sure. That way I can at least have real numbers for all the parameters.

 

[Brenspeed]

yeah, thats some bad air for sure! Heat effects blower cars a TON and the twin screws seem to be a lot more prone to heat soak as well. One run and your next pulls will definitely be lower (unless your knock sensors mystyrically think they want to add some timing.)

 

[Bestangyet 07]

Run #1 was 420hp 401tq. Run #2 was 419hp 390tq. They were back to back runs with thirty seconds in between. I am just wondering if you think I will get enough extra power from a local custom dyno tune to justify spending 350 to get it. If I stand a chance of gaining 40hp then maybe so. I do understand that e-mail tunes carry with them a great deal of liability. They also carry a shops reputation and blown motors do not help that. I would think that you would rather be on the safe side of tuning remotely, so your tunes would have to be conservative.

 

[Brenspeed]

Honestly i would go back to another dyno day on a cooler day and see where you are. IATs and DA are definitely huge!

 

[tylerxfire]

what type of dyno is it? numbers are numbers

 

[Bestangyet 07]

It was a dynojet.