408 issues... Opinions Wanted
408 issues... Opinions Wanted Anybody have any ideas how i can go from this:
to This
the problem...
The first graph was on some mushroomed valves, stock LS6 tb, Stock ls6 intake manifold, stock intake duct, and stock crank pulley
The Second graph includes a ported FAST 90 intake, Ported LS2 TB, SLP 25% underdrive pulley, New larger smoother intake bridge.
The car has started burning some oil which im pretty sure is valve seals. I didnt have the logger set up to see if it was knocking but ill check my plugs tomorrow. I made the recent pulls about 15k miles after i made the pulls in the first graph.
I am confused because i cant see any huge issues with the second graph. It looks like a good solid pull from a solid motor but the numbers are just low. What on earth could make the numbers suffer? i am running about 4 degrees less timing as it was my nitrous tune. But i highly doubt that is going to make me lose that much power?
:edit:
after looking at the graph a bit more it looks like i may have hit some knock around 5k. there is a little shift in the curve it seems?
to This
the problem...
The first graph was on some mushroomed valves, stock LS6 tb, Stock ls6 intake manifold, stock intake duct, and stock crank pulley
The Second graph includes a ported FAST 90 intake, Ported LS2 TB, SLP 25% underdrive pulley, New larger smoother intake bridge.
The car has started burning some oil which im pretty sure is valve seals. I didnt have the logger set up to see if it was knocking but ill check my plugs tomorrow. I made the recent pulls about 15k miles after i made the pulls in the first graph.
I am confused because i cant see any huge issues with the second graph. It looks like a good solid pull from a solid motor but the numbers are just low. What on earth could make the numbers suffer? i am running about 4 degrees less timing as it was my nitrous tune. But i highly doubt that is going to make me lose that much power?
:edit:
after looking at the graph a bit more it looks like i may have hit some knock around 5k. there is a little shift in the curve it seems?
Last edited by LostCauseZ06; Aug 4, 2008 at 02:48 AM.
11 Second Club
Joined: Jun 2005
Posts: 1,537
Likes: 0
From: Was New Orleans, but swam to Baton Rouge
Well, it is hard to say. First I would like more info on the second run. I have no idea what the correction factor is or the weather conditions. With that being said though. The first dyno was done in some really good temp, but the pressure sucks. Is there a different elevation between the dynos?
i am not sure on the correction factor issues. both dyno's were at the same elevation. The dyno was not the same dyno but this one was bought and installed/set up the day before i dyno'd. Its a brand new Dynojet 248x
also, we did not run A/F monitoring as my exhaust is dumped under the car. i have a wideband and my a/f is always a soiid 12.5-12.8
also, we did not run A/F monitoring as my exhaust is dumped under the car. i have a wideband and my a/f is always a soiid 12.5-12.8
11 Second Club
Joined: Jun 2005
Posts: 1,537
Likes: 0
From: Was New Orleans, but swam to Baton Rouge
i am not sure on the correction factor issues. both dyno's were at the same elevation. The dyno was not the same dyno but this one was bought and installed/set up the day before i dyno'd. Its a brand new Dynojet 248x
also, we did not run A/F monitoring as my exhaust is dumped under the car. i have a wideband and my a/f is always a soiid 12.5-12.8
also, we did not run A/F monitoring as my exhaust is dumped under the car. i have a wideband and my a/f is always a soiid 12.5-12.8
i really dont want to play the "dyno is broke" game though.
in your opinions... does the graph look like there is something mechanically wrong with the car? can you think of anything that could be wrong that could cause a loss of 40 RWHP but still provide a great looking graph?
in your opinions... does the graph look like there is something mechanically wrong with the car? can you think of anything that could be wrong that could cause a loss of 40 RWHP but still provide a great looking graph?
Your first dyno gave you a 1.13 correction in what was probably excellent conditions. Basically, you got a higher dyno number than was probably realistic. Your new dyno was probably a less favorable weather correction and it made it look like your dyno numbers suffered. See it all the time. Especially when you switch dynos.
__________________
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
Trending Topics
11 Second Club
Joined: Jun 2005
Posts: 1,537
Likes: 0
From: Was New Orleans, but swam to Baton Rouge
i really dont want to play the "dyno is broke" game though.
in your opinions... does the graph look like there is something mechanically wrong with the car? can you think of anything that could be wrong that could cause a loss of 40 RWHP but still provide a great looking graph?
in your opinions... does the graph look like there is something mechanically wrong with the car? can you think of anything that could be wrong that could cause a loss of 40 RWHP but still provide a great looking graph?
I would say the graph looks good. Personally, I have experienced a loss of over 50 rwhp due to some worn spark plugs. I had a plug with no cermaic left on it in one cylinder that was causing my drop. Even with the plug down my graph still looked good just not all the HP the engine should have.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Your first dyno gave you a 1.13 correction in what was probably excellent conditions. Basically, you got a higher dyno number than was probably realistic. Your new dyno was probably a less favorable weather correction and it made it look like your dyno numbers suffered. See it all the time. Especially when you switch dynos.
actually... not the case. 1.13 is very standard for up here. we have had upwards of 1.16 before. This is utah, 4400 Ft elevation and its been 105 the last week
I would say the graph looks good. Personally, I have experienced a loss of over 50 rwhp due to some worn spark plugs. I had a plug with no cermaic left on it in one cylinder that was causing my drop. Even with the plug down my graph still looked good just not all the HP the engine should have.
that is good to know. i made the pulls on VERY VERY old spark plugs that have quite a bit of oil contamination. maybe ill throw in some new plugs and try again.
Your original dyno was in the high 40s/low 50s with a 1.13 correction factor. If your next dyno was in the 90s or higher, the difference in correction is going to be much higher than going from 1.13 to 1.16. Temperature makes a HUGE difference.
If you're able to gather the weather conditions from both dyno days, that would shed a lot more light on the discrepancy in power.
__________________
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
good point. i will have to have him check what the correction factor was. he just bought the dyno and is not completely 100% on the software yet. he wasnt sure how to get it to show correction factor used.
I think the problem is in your original dyno session, 25.95 Baro? A 1.13 correction factor on a 48 degree day? If it was 80 degrees your correction factor would have been 1.20 or something crazy. If my calculation is correct your uncorrected "real" hp would be 423 hp.
I would do a search for barometric data on that day and see if it's correct. What is the baro on the latest dyno session?
I would do a search for barometric data on that day and see if it's correct. What is the baro on the latest dyno session?
conditions were correct, the air up here sucks...
Just found the real problem. Ran a leakdown test on the motor. gettin 42% leakdown on 2 cylinders compared to 20ish% on the good cylinders...
I had done a compression test before and knew something was probably up
1- 170
3- 215
5- 210
7- 170
is 42% leakdown rebuild time ? im guessing that it definately is because the good ole matco leakdown tester is saying that is mid/moderate leak
Just found the real problem. Ran a leakdown test on the motor. gettin 42% leakdown on 2 cylinders compared to 20ish% on the good cylinders...
I had done a compression test before and knew something was probably up
1- 170
3- 215
5- 210
7- 170
is 42% leakdown rebuild time ? im guessing that it definately is because the good ole matco leakdown tester is saying that is mid/moderate leak
yes, i trapped 120 MPH up here at this track (4400 ft) according to NHRA corrections that is roughly a 135 MPH trap at sea level.
i was on the dyno 3 times on different types of dyno's and i always made at least 470-480 RWHP
i was on the dyno 3 times on different types of dyno's and i always made at least 470-480 RWHP
Huh... "is 42% leakdown rebuild time ?"
1& 7 dropping 40# of compression. You mentioned "mushroomed valves"...High EGT?
20% leak, on a hipo application would scare me.
Sounds like it's back on the engine stand time....
1& 7 dropping 40# of compression. You mentioned "mushroomed valves"...High EGT?
20% leak, on a hipo application would scare me.
Sounds like it's back on the engine stand time....
there are quite a few miles on the engine when i actually looked at my logs of when i threw it in. it has served its purpose quite well 
It has well over 20k miles of pretty decent abuse as well as daily driven in the rain/snow.
It has well over 20k miles of pretty decent abuse as well as daily driven in the rain/snow.