Bad Dyno Results.... :(
Thread Starter
Drifting
Joined: Oct 2001
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From: Round Rock,Austin, Texas
Bad Dyno Results.... :(
A few months back I had my car dynoed on a dynojet with just Headers and Roller Rockers and the car put down 275rwhp. Since then I did heads and cam and ported intake to match along with underdive pulley. Well I finally got the car back with a dyno tune and the number cannot be right. Keep in mind it was on a mustang dyno. According to the dyno the car put down 265rwhp. How can this be? The car feels strong but puts down numbers that are worse than before. I know the 2 types of dynos are different in numbers but this just doesnt seem right at all.
Team Owner
Joined: Mar 2000
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From: Boston, MA
Mustang dynos report WAY smaller #s. You're a glutten for punishment changing dyno styles like that. If you're just interested in a peak # then use a dynojet. If you're interested in tuning the car across the whole band in more real life type conditions then use a mustang dyno.
Team Owner
Joined: Aug 2000
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St. Jude Donor '14
Originally Posted by RadPolo96
A few months back I had my car dynoed on a dynojet with just Headers and Roller Rockers and the car put down 275rwhp. Since then I did heads and cam and ported intake to match along with underdive pulley. Well I finally got the car back with a dyno tune and the number cannot be right. Keep in mind it was on a mustang dyno. According to the dyno the car put down 265rwhp. How can this be? The car feels strong but puts down numbers that are worse than before. I know the 2 types of dynos are different in numbers but this just doesnt seem right at all.
Also, have you tuned it further after the extra mods ?
Race Director
Joined: Jan 2002
Posts: 12,263
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From: O'Fallon Missouri
I agree with Scorp on the Mustang dyno showing lower numbers. But, I am beginning to question the Precision Ported heads, seems they just aren't performing like their competitors. Also, the shop that ported my heads cautioned against porting the LT1 intake, said the runners were short (around 4") and would hurt performance by decreasing port velocity.
I hope you just have a bad tune, and not a bad port job.
-Mike
I hope you just have a bad tune, and not a bad port job.
-Mike
Team Owner
Joined: Mar 2000
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From: Boston, MA
Originally Posted by LT4-Z51
There is no way those numbers are right I just had my LT4 dynoed yesterday for the first time & with only a adjustable fuel reg. & cold air induction I got 310 HP & 311 TQ. at the rear wheels .
On a dynojet or a mustang dyno?
Le Mans Master
Joined: Jul 1999
Posts: 8,683
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From: Phoenix AZ
Using two completely different dynos to measure output really defeats the purpose of them. Regardless of the current numbers...how does the car feel? Does it feel faster than before? Can you go back to the original dyno that gave you your first numbers?
You should certainly be making more power than 265. Who tuned the computer for you? The average numbers for a setup like yours is in the 350-360 area...and even with the different reading from a Mustang and a Dynojet, I doubt there is THAT much of a difference!
You should certainly be making more power than 265. Who tuned the computer for you? The average numbers for a setup like yours is in the 350-360 area...and even with the different reading from a Mustang and a Dynojet, I doubt there is THAT much of a difference!
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Le Mans Master
Joined: Jul 1999
Posts: 8,683
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From: Phoenix AZ
Also, why are you using an LS1 MAF sensor? Be very careful changing the MAF like that without having someone really look into the computer, or using a MAF translator. I switched my MAF ends once with some higher flowing units and it killed the air/fuel on the car.
Team Owner
Joined: Mar 2000
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From: Boston, MA
There certainly can be depending on the load the mustang dyno operator is putting on the rollers. One of our guys up here who's C4 typically sees low low 11s and mid 10s with a small shot of juice only put down ~318rwhp on a mustang dyno recently. 318 is 4 less than my own car on a dynojet which has only gone 12.8x.
Le Mans Master
Joined: Jul 1999
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From: Phoenix AZ
Originally Posted by scorp508
There certainly can be depending on the load the mustang dyno operator is putting on the rollers. One of our guys up here who's C4 typically sees low low 11s and mid 10s with a small shot of juice only put down ~318rwhp on a mustang dyno recently. 318 is 4 less than my own car which has only gone 12.8x.
Team Owner
Joined: Mar 2000
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From: Boston, MA
Originally Posted by Zix
Wow!! That's a lot more than I would have imagined! I thought it hung around the 10-12% area. I've never been on a Mustang dyno...nobody I know has one in Phoenix because everyone wants to see the highest numbers possible!
Yeah I was quite shocked myself. My friend called and told me to guess what it made.... so I did up in the 400s. When he told me I nearly passed out.
Le Mans Master
Joined: Jan 2003
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From: Portland Oregon
Originally Posted by RadPolo96
A few months back I had my car dynoed on a dynojet with just Headers and Roller Rockers and the car put down 275rwhp. Since then I did heads and cam and ported intake to match along with underdive pulley. Well I finally got the car back with a dyno tune and the number cannot be right. Keep in mind it was on a mustang dyno. According to the dyno the car put down 265rwhp. How can this be? The car feels strong but puts down numbers that are worse than before. I know the 2 types of dynos are different in numbers but this just doesnt seem right at all.
Thread Starter
Drifting
Joined: Oct 2001
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From: Round Rock,Austin, Texas
Well like I said the dyno jet was before all my mods except fpr headers and RR's. I just got the car back and had it tuned on a mustang dyno after all the new stuff. The Butt O Meter definatley says its faster but I was a little disapointed. On the dyno I put down 265.5@5450rpm and 273.3@3950. At peak hp my air fuel is 12.6 and lookin at the charts ...it looks like 13 and a half at idle but its hard to understand these charts. Also people have been tellin me that the Torque converter and gears also steal hp along with being and automatic. Also sorry for the misprint...its a LT1 MAF.
Le Mans Master
Joined: Jul 1999
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From: Phoenix AZ
An auto car does, on average, lose a little more to the drivetrain than a manual car. It just sounds like you need to get back on a Dynojet to really try and compare numbers. The A/F sounds like it's pretty good 
Le Mans Master
Joined: Jan 2003
Posts: 8,596
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From: Portland Oregon
Originally Posted by RadPolo96
Well like I said the dyno jet was before all my mods except fpr headers and RR's. I just got the car back and had it tuned on a mustang dyno after all the new stuff. The Butt O Meter definatley says its faster but I was a little disapointed. On the dyno I put down 265.5@5450rpm and 273.3@3950. At peak hp my air fuel is 12.6 and lookin at the charts ...it looks like 13 and a half at idle but its hard to understand these charts. Also people have been tellin me that the Torque converter and gears also steal hp along with being and automatic. Also sorry for the misprint...its a LT1 MAF.
Team Owner
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St. Jude Donor '14
13:1 at idle ? have you read your spark plugs ? that's a bit rich for idle. This would cause your throttle response off idle to be a bit rough especially if you allow it to idle for a while. This would also cause poor performance till the plugs cleaned up after some sustained reving.