Dyno results going the wrong way?
Thread Starter
Drifting
Joined: Oct 2002
Posts: 1,898
Likes: 35
From: Fairview Hts. IL
Dyno results going the wrong way?
Earlier this week I had my first dyno. The results were 307.6 hp/317tq. Today I had another run 298hp/290tq. What's going on? I have added a blackwing, coupler, magna-flow exhaust w/ x-pipe. . .shouldn't I be getting dyno results closer to 320 or 330 hp?
By the way, I have an A4 w/ 2.73 gears. :confused:
By the way, I have an A4 w/ 2.73 gears. :confused:
Drifting
Joined: Aug 2002
Posts: 1,317
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From: Lancaster CA
Re: Dyno results going the wrong way? (hogurt)
You don't mention what year you have. If you have a 97 or 98, you may need to relocate the vacume line to the fuel pressure regulator. There's a kit out to do that. I got mine from Vortex I think.
If that's the case, what's happening is the mod to the air intake has reduced the vacume on the FPR causing you to run richer. That could cause a decrease in HP. :cheers:
If that's the case, what's happening is the mod to the air intake has reduced the vacume on the FPR causing you to run richer. That could cause a decrease in HP. :cheers:
Team Owner
Joined: Sep 1999
Posts: 20,054
Likes: 44
From: Swansea IL
Re: Dyno results going the wrong way? (hogurt)
hogurt who did your Dyno? I live in Shiloh. We need to hook up sometime. I work at Scott AFB and belong to the Looking Glass Corvette Club.
Tom
USAF Retired
Tom
USAF Retired
Thread Starter
Drifting
Joined: Oct 2002
Posts: 1,898
Likes: 35
From: Fairview Hts. IL
Re: Dyno results going the wrong way? (AFVETTE)
I had both runs at Mustang Muscle in St. Louis. So, what do you do to become a member of a corvette club? I have heard of the Looking Glass club. . .
:confused:
:confused:
Drifting
Joined: Aug 2002
Posts: 1,317
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From: Lancaster CA
Re: Dyno results going the wrong way? (hogurt)
Oh, good point. I have a 2002 Coupe.
By the way, I am really disappointed with the results from these dyno's.
:U
By the way, I am really disappointed with the results from these dyno's.
:U
Team Owner
Joined: Sep 1999
Posts: 20,054
Likes: 44
From: Swansea IL
Re: Dyno results going the wrong way? (hogurt)
We held a Club Dyno Day last year at Mustang Muscle. Planning on another Dyno Day soon. Most folks seem to do a lot of mods this time of year so we plan on re-testing. We have found another shop that can/will dyno tune for $275 From what I've seen many mods don't produce the desired results until the car is dyno tuned. We have a few club buddies getting ready to install the FLP headers, plugs wires etc and are anxious to have the car tuned.
That could be all that your car needs to extract all the HP there is. Air Fuel Ratio's play a critical role in HP gains/losses. When I dyno'd at MM my AFR's fell to 11.0:1 at 5200 RPM's - my car is running REAL RICH. My MN6 with Blackwing and Corsa Indy's Dyno's at 292 RWHP not what I expected from all the claims/posts found out here. I figured the car stock was good for 300, then add 10 for thye BW and another 5 for the Indy's so by that standard I was hoping to see 315 RWHP not 292. What were your AFR's?
Give me a call at 632-4647 and maybe we can meet somewhere for a beer and BS.
Tom
That could be all that your car needs to extract all the HP there is. Air Fuel Ratio's play a critical role in HP gains/losses. When I dyno'd at MM my AFR's fell to 11.0:1 at 5200 RPM's - my car is running REAL RICH. My MN6 with Blackwing and Corsa Indy's Dyno's at 292 RWHP not what I expected from all the claims/posts found out here. I figured the car stock was good for 300, then add 10 for thye BW and another 5 for the Indy's so by that standard I was hoping to see 315 RWHP not 292. What were your AFR's?
Give me a call at 632-4647 and maybe we can meet somewhere for a beer and BS.
Tom
Thread Starter
Drifting
Joined: Oct 2002
Posts: 1,898
Likes: 35
From: Fairview Hts. IL
Re: Dyno results going the wrong way? (AFVETTE)
Well, the first run I had an air fuel ratio 11.7. Unfortunately, since I didn't make any more changes, I didn't get the A/F checked on the last run. So, where should I go to get the car dyno tuned?
By they way, I am planning on getting 3.42's and a torque converter next summer. . .should I just hold off until then?
By they way, I am planning on getting 3.42's and a torque converter next summer. . .should I just hold off until then?
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Pro
Joined: Oct 2000
Posts: 732
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From: Sierra Vista, Arizona
Re: Dyno results going the wrong way? (hogurt)
Your numbers are pretty much right on for the mods you have. I have a 2001 A4 with basically the same mods you have except I am also running FLP Long Tube Headers. I think my last dyno was 322.7... Keep in mind you are going to pull lower numbers with an A4 than a manual....
Thread Starter
Drifting
Joined: Oct 2002
Posts: 1,898
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From: Fairview Hts. IL
Re: Dyno results going the wrong way? (Norris)
My concern is a drop in tq/hp? Basically, from 307 to 298? Don't most stock vettes pull 300rwhp? What would you expect from a stock A4/2.73 diff? What is the best estimate for an Automatic drivetrain loss?
By the way, I just purchased a 3.42 from another forum member!!! Going to Alabama to pick it up next weekend!!! :cheers: to Mike Plummer.
Time for a vacation. . . differential . . .vacation. . .
By the way, I just purchased a 3.42 from another forum member!!! Going to Alabama to pick it up next weekend!!! :cheers: to Mike Plummer.
Time for a vacation. . . differential . . .vacation. . .
Race Director
Joined: Nov 1999
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From: Greer SC
Cruise-In II Veteran
Re: Dyno results going the wrong way? (hogurt)
On our original engine, after the Vortex & exhaust, we dynoed 293 RWHP & 304 RWTQ. The after-market air intakes do not have the dynamic impact on HP for '01's & up as they do for '97-'00 because of the air intake improvements & the timing changes on the '01.
Thread Starter
Drifting
Joined: Oct 2002
Posts: 1,898
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From: Fairview Hts. IL
Re: Dyno results going the wrong way? (NJVetteGuy)
I did have the wideband running for the runs of 307 and 303. The A/F ratio was about 11.5 for each of them. (from 14.8 to 11.6@4900 and 11.5@5000)
From what I understand, the A/F ratio would be best at 13.1! What kind of gains should I see if I can get the A/F ratio where it is supposed to be?
From what I understand, the A/F ratio would be best at 13.1! What kind of gains should I see if I can get the A/F ratio where it is supposed to be?
Pro
Joined: Oct 2000
Posts: 732
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From: Sierra Vista, Arizona
Re: Dyno results going the wrong way? (hogurt)
My concern is a drop in tq/hp? Basically, from 307 to 298? Don't most stock vettes pull 300rwhp? What would you expect from a stock A4/2.73 diff? What is the best estimate for an Automatic drivetrain loss?
Instructor
Joined: Aug 2001
Posts: 192
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From: Virginia Chesapeak
Re: Dyno results going the wrong way? (Norris)
Don't go crazy with dyno numbers on an A4, they just don't dyno as good as an M6. Take it to the track and see how good your car is running that is a much better test. What gear ratio you have can also effect your dyno readings. The bigger the rear the lower the dyno reading will be. For example the same car with 3.42s will have a higher dyno reading than the same car with 3.73s.
98 A4
Donaldson Blackwing
Cartek Stage 2 Heads
Cartek M Cam
ST3500
3.73 Gears
LS6 Intake
Underdrive Pulley
B&M 28,000 Tranny Cooler
172 T.Stat
[Modified by MC98, 12:47 PM 11/17/2002]
98 A4
Donaldson Blackwing
Cartek Stage 2 Heads
Cartek M Cam
ST3500
3.73 Gears
LS6 Intake
Underdrive Pulley
B&M 28,000 Tranny Cooler
172 T.Stat
[Modified by MC98, 12:47 PM 11/17/2002]
Team Owner
Joined: Sep 1999
Posts: 20,054
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From: Swansea IL
Re: Dyno results going the wrong way? (MC98)
MC98 makes a valid point. Too many High Performance car owners believe the Dyno is the Holy Grail. The real truth meter is the 1/4 mile. Granted a strong car in the hands of an un-skilled driver will look like a dog and vice versa. The wide-band dyno does help pin pont problem area's like AFR's. When we dyno'd at MM each owner was allowed to drive, since I never dyno'd before my technique was probably flawed from what I'm now hearing. I got the car into 4th gear, held the tach at 2200 RPM's and when I was ready I gave the tech a thumbs up (which started the run) and slowly rolled into the throttle until about 3500 RPM then mashed it. I have been told I should have just mashed it from the start. Not sure what the difference is but that's what I'm being told. I've seen other dyno test and that seems to be the technique so maybe I screwed the pooch on my run. I did make a second run but temps were up and I posted slightly lower numbers.
But having poor AFR's can't be good, so that's probably were I'll spend any more mod money - a good dyno tune and see what I gain.
Tom
But having poor AFR's can't be good, so that's probably were I'll spend any more mod money - a good dyno tune and see what I gain.
Tom
