Dyno question
Thread Starter
Melting Slicks
Joined: Dec 2001
Posts: 2,437
Likes: 1
From: Gainesville Fl
Dyno question
i had the LT4 dynoed this weekend at the museum. it dynoed 308rwhp and 314rwtq. This is a lot lower than what it should have been because i have a skip in my engine. I think it is a plug or a wire since it has been doing it since i put on headers. but i know it is igniton because the airfuel ratio showed it was running WAAAAAAAY rich. so im guessing that one cylinder isnt firing once every few rotations of the crank. any thoughts as to how much power this might be costing me? if u devide up 308 into 8 cylinders thats about 38hp per cylinder. if one of these isnt producing full power then thats about 30 or so hp im losing. does hat mean i could be running close to 340rwhp with an engine that runs smoothly and has a good A/F ratio?
Last edited by 1996man; May 7, 2006 at 11:41 PM.
Race Director
Joined: Aug 2003
Posts: 11,043
Likes: 3
From: San Jose Pat Tillman - American Hero
Originally Posted by 1996man
i had the LT4 dynoed this weekend at the museum. it dynoed 308rwhp and 314rwtq. This is a lot lower than what it should have been because i have a skip in my engine. I think it is a plug or a wire since it has been doing it since i put on headers. but i know it is igniton because the airfuel ratio showed it was running WAAAAAAAY rich. so im guessing that one cylinder isnt firing once every few rotations of the crank. any thoughts as to how much power this might be costing me? if u devide up 308 into 8 cylinders thats about 38hp per cylinder. if one of these isnt producing full power then thats about 30 or so hp im losing. does hat mean i could be running close to 340rwhp with an engine that runs smoothly and has a good A/F ratio?
Elite Torch Red Member
Joined: Sep 1999
Posts: 57,805
Likes: 23
From: Exit 89 GSP,Lakewood,NJ The Land Of Mojo
Cental/South NJ Events Coordinator
CI 1-2-3-4-5-6-7-8-9-10-11-12 Vet
CI-II Burnout & Drag Champ
St. Jude Donor '03-'04-'05-'06-'07
Those numbers are about right for a stock LT4. The mods you made may be hurting rather than helping. I know when I did muffler eliminators, I lost power.
Did you ever dyno it bone stock? Also remember the weather conditions in KY will be different than those in FLA.
Did you ever dyno it bone stock? Also remember the weather conditions in KY will be different than those in FLA.
Le Mans Master
Joined: Jul 1999
Posts: 8,683
Likes: 6
From: Phoenix AZ
Originally Posted by 1996man
i had the LT4 dynoed this weekend at the museum. it dynoed 308rwhp and 314rwtq. This is a lot lower than what it should have been because i have a skip in my engine. I think it is a plug or a wire since it has been doing it since i put on headers. but i know it is igniton because the airfuel ratio showed it was running WAAAAAAAY rich. so im guessing that one cylinder isnt firing once every few rotations of the crank. any thoughts as to how much power this might be costing me? if u devide up 308 into 8 cylinders thats about 38hp per cylinder. if one of these isnt producing full power then thats about 30 or so hp im losing. does hat mean i could be running close to 340rwhp with an engine that runs smoothly and has a good A/F ratio?
Melting Slicks
Joined: May 2003
Posts: 3,490
Likes: 68
From: Hewitt NJ
Originally Posted by Zix
Hard to put a HP number on a miss, can you post up the dyno sheet? What was the AFR?
Seein the A/F ratio will give us a better idea. I would say that you are probably down 10-15 RWHP based on your mods.
Thread Starter
Melting Slicks
Joined: Dec 2001
Posts: 2,437
Likes: 1
From: Gainesville Fl
Originally Posted by corvetteronw
You can dyno your Corvette at the NCM? I learn something every day here!
As for the A/F.... I will try and scan my dyno sheet and post it tomorrow but loooking at my graph it looks about between 14 and 15 untill 2k rpms then it drops down to 11 by about 2.5k rpms and stays there untill about 5.5k rpms when it drops even lower. I have a feeling if the A/F was in the correct place the entire time i would be making a LOT more power. any ideas?
Le Mans Master
Joined: Jul 1999
Posts: 8,683
Likes: 6
From: Phoenix AZ
Originally Posted by 1996man
I dont think you can dyno it everyday there. It was on a portable dynojet they had set up for the C4 gathering this weekend.
As for the A/F.... I will try and scan my dyno sheet and post it tomorrow but loooking at my graph it looks about between 14 and 15 untill 2k rpms then it drops down to 11 by about 2.5k rpms and stays there untill about 5.5k rpms when it drops even lower. I have a feeling if the A/F was in the correct place the entire time i would be making a LOT more power. any ideas?
As for the A/F.... I will try and scan my dyno sheet and post it tomorrow but loooking at my graph it looks about between 14 and 15 untill 2k rpms then it drops down to 11 by about 2.5k rpms and stays there untill about 5.5k rpms when it drops even lower. I have a feeling if the A/F was in the correct place the entire time i would be making a LOT more power. any ideas?
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Thread Starter
Melting Slicks
Joined: Dec 2001
Posts: 2,437
Likes: 1
From: Gainesville Fl
Originally Posted by Zix
If you're at roughly 11.0:1 and lower you are certainly running very rich. Do you have any exhaust leaks before the O2 sensors at all? When you find the culprit I would also recommend changing the plugs...they may be a bit fouled at this point...maybe not, but I would do it if I had the choice for peace of mind.
How much power do you think i am losing running that rich?
Le Mans Master
Joined: Jul 1999
Posts: 8,683
Likes: 6
From: Phoenix AZ
Originally Posted by 1996man
How much power do you think i am losing running that rich?
