Modded Mustang Forums banner

1 - 20 of 23 Posts

·
Registered
Joined
·
1,668 Posts
Discussion Starter #1
hey guys, just a quick question. i went to the dyno to have it retuned with the smaller pulley (2 tengths smaller). last time my car dyno'd @ 335 whp and it dropped since then because of the hotter air. i know colder air makes more horsepower but i wasn't sure of how much it affected it. last time i dyno'd was 12/21 and the temperature was 62 degrees, today it was 94. that's a huge difference, just wondering how much of a difference it makes.
thanks joshua
 

·
Registered
Joined
·
6,973 Posts
What did it make this time? Most cars will always dyno higher right after a blower install because the belt is nice and tight. I'm guessing you kept the same belt so it probably had to do with some belt stretch, which is normal, and the hotter air. Not sure what the psi difference would be on a P1SC by dropping .2" on the pulley, but on a Vortech V1 S it's like 1.5psi going from 3.6 to 3.4. What psi did it make last time on the dyno vs this time?
 

·
Registered
Joined
·
678 Posts
Fluid temps, elevation, atmospheric temps, barometric pressure all of that affect the numbers. Comparing dyno numbers like comparing numbers is sort of like comparing apples and oranges, or at least red delicious to granny smiths. The SAE correction factor is suppose to even out the differences but the truth is if you dyno your car at sea level in Alaska in January its going to make more power than if you dyno your car in Denver in August. That's why we don't race dynos.
 

·
Registered
Joined
·
11,469 Posts
that big of a temp increase will bring the numbers down along with the boost your motor sees. there is a lot of things that come into play, one is humidity, and barometric pressure of the day. even though you went down a pulley you may not have spun it fast enough to overcome the negative effects of the day. also you should have asked your tuner if your car was pulling timing from the heat
 

·
Registered
Joined
·
1,668 Posts
Discussion Starter #5
that big of a temp increase will bring the numbers down along with the boost your motor sees. there is a lot of things that come into play, one is humidity, and barometric pressure of the day. even though you went down a pulley you may not have spun it fast enough to overcome the negative effects of the day. also you should have asked your tuner if your car was pulling timing from the heat
he said that even though i went down a pulley boost only went from 8.64 psi to 9.05 psi. the difference was .42 whp. i lost despite going smaller pulley & more boost. he said the heat, humidity, and b-pressure was to account for the loss. first dyno he said it was real rich, so he had to fix that from when it was tuned in december. that it will make more power in the colder months, i was just wondering what the typical loss is due to such weather differences.
 

·
Registered
Joined
·
678 Posts
The only way to really compare would have been to make pulls with the old pulley and tune then swap to the smaller pulley and retune it.

I would suggest getting it retuned when the whether cools off again. I have seen more than a few people have cars tuned in the heat of summer and when the first crisp fall day comes around they end up melting down an engine because of the much cold, dense air. At the very least if you don't have a wide band then get one.
 

·
Registered
Joined
·
3,430 Posts
My car was tuned initially when it was 100 degrees inside the room (literally) and it put down 408 rwhp.

4 months later I got it re-dynoded (on the same dyno) during a dyno day and made 433 rwhp. It was in the mid to low 60's.

I saw quite a increase from the change of weather. I would assume the opposite is also very possible
 

·
Registered
Joined
·
21,024 Posts
Yea today was the first muggy day out, like 78 degrees but it was like 92% humidity, car felt slow to be honest.

But then again who knows, with my luck Im probally getting belt slip.
 

·
Registered
Joined
·
1,668 Posts
Discussion Starter #10
My car was tuned initially when it was 100 degrees inside the room (literally) and it put down 408 rwhp.

4 months later I got it re-dynoded (on the same dyno) during a dyno day and made 433 rwhp. It was in the mid to low 60's.

I saw quite a increase from the change of weather. I would assume the opposite is also very possible
okay that makes me feel better, i hope once it cools off to crack 400's with the cams put in, hopefully long-tubes by then too. nice numbers man, very nice
 

·
Registered
Joined
·
1,668 Posts
Discussion Starter #11
Yea today was the first muggy day out, like 78 degrees but it was like 92% humidity, car felt slow to be honest.

But then again who knows, with my luck Im probally getting belt slip.
i hope it's not your belt slipping, i don't see how anyone's car can run at it's best in this type of weather man
 

·
Registered
Joined
·
21,024 Posts
Lol thanks man same here. I think Im about to just buy a Riechard Racing 2.8" pulley with this Gates Micro V belt. That way I really wont have any worries.

Cant wait to see your numbers with the cams man. Should be good.
 

·
Registered
Joined
·
11,469 Posts
Lol thanks man same here. I think Im about to just buy a Riechard Racing 2.8" pulley with this Gates Micro V belt. That way I really wont have any worries.

Cant wait to see your numbers with the cams man. Should be good.
i would be careful with that pulley, the rr grips real good so if you were loosing boost from belt slip you may pick up quite a bit with the rr one
 

·
Registered
Joined
·
21,024 Posts
Thanks for the headsup, but **** more boost is more fun. Lol, I really dont even care if the motor grenades. Ill figure it out. Whether its a temporary junkyard motor, or taking out a personal loan for a built motor. So **** it. The worst part will be the tow lol
 

·
Registered
Joined
·
21,024 Posts
Speaking of, I know Ive procrasinated this for a while, but I think I might go with that 4 core intercooler stal. If I do, I just dont know what pulley to run. Ill probally try finding a used RR one, so like a 3.2? 3.1?
 

·
Registered
Joined
·
11,469 Posts
with a cx 4 core you may pick up quite a bit of boost with a rr pulley, im not an expert on the v1 s trim blower but i imagine 10# with a rr pulley and 4 core would probably be a 3.1 or 3.0, but that may get you closer to 12-13# so im not sure
 

·
Registered
Joined
·
21,024 Posts
Yeah true that. I think Ill just try a 3.1, if Im making like 12psi, Im sure my tuner will just pull timing. Or I could shift early.
 

·
Registered
Joined
·
11,469 Posts
i still cant belive you have not got the new ic, it is pretty cheap and worth it. i would bet your hp would really go up with a ic swap, and a power pipe.
 

·
Registered
Joined
·
21,024 Posts
I know man, like I said im a procrasinator lol. I dont think I have anything to cut that bumper support with either. I can find something, but I dont want to make it look like ****. I have some extra money in May, doing Cobra/mach front brakes, probally a set of MT's, and the pulley and 4 core intercooler. Then a re-tune.
 

·
Registered
Joined
·
11,469 Posts
if i were to do it over again i would have just cut the entire center section out. and hung the ic on brackets. this would help with air flow and still allow you to hang your foam bumper support. or gone with the bumper bar
 
1 - 20 of 23 Posts
Top