379 HP - Dynojet Problems?
Thread Starter
Staging Lane
Joined: Nov 2006
Posts: 60
Likes: 0
From: Lacey, WA
379 HP - Dynojet Problems? Hi All, last week I got my '97 M6 C5 back from Tom Wong. He installed a set of Ported LS6 heads (with all new valvetrain) and a 232/234 .595/.598 Camshaft. He also installed a host of other supporting upgrades.
After his tune - my car made 400 whp and 362 wtq on his Mustang Dyno.
Since everyone on "the interwebs" seems to be running on a Dynojet type dyno, I wanted to throw my car on one too and see how my hand ported heads with this cam stacked up against some of the CNC ported heads. I was expecting somewhere near 410-430whp...
So a week after getting it back from Tom, i threw it on Turbo Technologies Inc's Dyno here in WA, and put down 379 whp 350 tq... ( I didn't get AFR... But Tom had it dialed in Perfect on his Mustang Dyno)
I was expecting over 400... Any ideas whats going on?
How often have folks seen a Dynojet Read 5% or more lower than a Mustang dyno? Tom said his dyno usually reads at least 10hp lower than other dynos... sometimes more...
I'm gonna run out and check some things when i get home... like clogged vararam or loose plug wire (which happened to me twice now)
Any other ideas?
Dan
After his tune - my car made 400 whp and 362 wtq on his Mustang Dyno.
Since everyone on "the interwebs" seems to be running on a Dynojet type dyno, I wanted to throw my car on one too and see how my hand ported heads with this cam stacked up against some of the CNC ported heads. I was expecting somewhere near 410-430whp...
So a week after getting it back from Tom, i threw it on Turbo Technologies Inc's Dyno here in WA, and put down 379 whp 350 tq... ( I didn't get AFR... But Tom had it dialed in Perfect on his Mustang Dyno)
I was expecting over 400... Any ideas whats going on?
How often have folks seen a Dynojet Read 5% or more lower than a Mustang dyno? Tom said his dyno usually reads at least 10hp lower than other dynos... sometimes more...
I'm gonna run out and check some things when i get home... like clogged vararam or loose plug wire (which happened to me twice now)
Any other ideas?
Dan
See what the dyno correction was. Maybe the dyno weather station gave a jacked-up correction and made your numbers lower. It happens. 
__________________
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.
Thread Starter
Staging Lane
Joined: Nov 2006
Posts: 60
Likes: 0
From: Lacey, WA
Originally Posted by Patrick G
See what the dyno correction was. Maybe the dyno weather station gave a jacked-up correction and made your numbers lower. It happens.
.98
Uncorrect numbers were like 382...
Bout 65* and 40% humidity... not too bad... Cooler and Less Humid than the day my 400whp Run was done in Vancouver on the Mustang Dyno!
-Dan
Thread Starter
Staging Lane
Joined: Nov 2006
Posts: 60
Likes: 0
From: Lacey, WA
How do I check my plug wires? Maybe I'm not firing on all 8 Cylinders?
379 / 7cyl = 54hp Per Cylinder.
54 * 8 = 433hp (Which is where i should be on a Dynojet, or atleast close...)
Since i made 400 on a conservative Mustang dyno, I was expecting 420-430 with this setup on the DJ (similar to what everyone else w/ this setup makes) and getting 379 might indicate a problem with my car?
How often do people see Dynojet type dynos throw numbers LOWER than Conservative Mustang dynos?
-Dan
379 / 7cyl = 54hp Per Cylinder.
54 * 8 = 433hp (Which is where i should be on a Dynojet, or atleast close...)
Since i made 400 on a conservative Mustang dyno, I was expecting 420-430 with this setup on the DJ (similar to what everyone else w/ this setup makes) and getting 379 might indicate a problem with my car?
How often do people see Dynojet type dynos throw numbers LOWER than Conservative Mustang dynos?
-Dan
Thread Starter
Staging Lane
Joined: Nov 2006
Posts: 60
Likes: 0
From: Lacey, WA
Originally Posted by delsold
hell with the numbers...before you go thinking your car isnt running correctly does it seem to run ok? run as strong as it did when it was tuned?
It has a phenomenal amount of carbon buildup on the back of my car... I know the aerodynamics of the back of corvettes pull a bunch of **** up... but not normally is it all black carbon... usually its road film...
-Dan
Thread Starter
Staging Lane
Joined: Nov 2006
Posts: 60
Likes: 0
From: Lacey, WA
So I brought it back down to Tom Wong and threw it on the dyno.
Pretty interesting results...
The AFR was flat, right where it should be up until about 5200 RPMs... then it DIVES to 9:1... pig rich... and black smoke billows out the back. Which explains the ridiculous amount of carbon crap i've had on the back of my car...
The only thing we could find that could cause the problem (after trying a couple things) was the air meter. Its most likely getting spikes up top, and the ECU is preparing for a massive amount of air by dumping fuel in...
I'm going to replace that and redyno it... we'll see if that fixes the issue.
Of note - the weather was nice, and my car peaked at ~396 whp with a 9:1 AFR from 5200 to 6400 RPM.... LOL With a correct AFR Tom suspects i would've hit ~415whp. hehe
So turns out the Dynojet may not have been wrong after all, and my car may indeed have a problem...
Update to come...
-Dan
Pretty interesting results...
The AFR was flat, right where it should be up until about 5200 RPMs... then it DIVES to 9:1... pig rich... and black smoke billows out the back. Which explains the ridiculous amount of carbon crap i've had on the back of my car...
The only thing we could find that could cause the problem (after trying a couple things) was the air meter. Its most likely getting spikes up top, and the ECU is preparing for a massive amount of air by dumping fuel in...
I'm going to replace that and redyno it... we'll see if that fixes the issue.
Of note - the weather was nice, and my car peaked at ~396 whp with a 9:1 AFR from 5200 to 6400 RPM.... LOL With a correct AFR Tom suspects i would've hit ~415whp. hehe
So turns out the Dynojet may not have been wrong after all, and my car may indeed have a problem...
Update to come...
-Dan
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Staging Lane
Joined: Nov 2006
Posts: 60
Likes: 0
From: Lacey, WA
So I went to Tom's last night and made a bunch of passes on his dyno trying to diagnose the problem.
The AFR goes Pig Rich for no apparent reason above 5k RPMs...
We tossed in a new MAF and rescaled the tune - but got the same results...
The injectors, and the Air Flow readings all appear normal. Tom doesn't see any indication or explanation for why the AFR dives to 10:1.
We pulled the Evap line, and some other fuel related vacuum line and checked for fuel... also made a pass - no difference... the car still dives pig rich...
Tom tried pulling a BUNCH of fuel - to really lean it out up top... but, surprisingly, that made it worse... went even more rich... 9:1
I reseated all the injector connections, and wiggled all the injectors, and reconnected the harness wires, and made a pass. (This after 2.5 hours of trying stuff...) and out of no where the AFR was laser flat...
So re tried it again... same result.. laser flat AFR. So we put the stock MAF back on and uploaded the original tune and reran it. Same result... everything seems fine now...
I'm not entirely sure what, if anything, we fixed. And/or what the problem was.... But for now, i guess my only option is to watch for clouds of black crap out the back again, and use that as my indicator to if i start running rich again...
Tom also suggested cleaning all the grounds... especially around my PCM...
Does anyone have any ideas where the extra fuel would be coming from, and/or what might be going on there?
Dan
The AFR goes Pig Rich for no apparent reason above 5k RPMs...
We tossed in a new MAF and rescaled the tune - but got the same results...
The injectors, and the Air Flow readings all appear normal. Tom doesn't see any indication or explanation for why the AFR dives to 10:1.
We pulled the Evap line, and some other fuel related vacuum line and checked for fuel... also made a pass - no difference... the car still dives pig rich...
Tom tried pulling a BUNCH of fuel - to really lean it out up top... but, surprisingly, that made it worse... went even more rich... 9:1
I reseated all the injector connections, and wiggled all the injectors, and reconnected the harness wires, and made a pass. (This after 2.5 hours of trying stuff...) and out of no where the AFR was laser flat...
So re tried it again... same result.. laser flat AFR. So we put the stock MAF back on and uploaded the original tune and reran it. Same result... everything seems fine now...
I'm not entirely sure what, if anything, we fixed. And/or what the problem was.... But for now, i guess my only option is to watch for clouds of black crap out the back again, and use that as my indicator to if i start running rich again...
Tom also suggested cleaning all the grounds... especially around my PCM...
Does anyone have any ideas where the extra fuel would be coming from, and/or what might be going on there?
Dan
Check to see if your cat protection mode is dumping fuel. Many pcms will dump fuel to protect cats at higher rpm. My 2007 Suburban did it. After we fixed that, we gained close to 30 rwhp.
__________________
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.
Thread Starter
Staging Lane
Joined: Nov 2006
Posts: 60
Likes: 0
From: Lacey, WA
Originally Posted by Patrick G
Check to see if your cat protection mode is dumping fuel. Many pcms will dump fuel to protect cats at higher rpm. My 2007 Suburban did it. After we fixed that, we gained close to 30 rwhp.
Any other ideas are welcome!
Thanks,
Dan
Thread Starter
Staging Lane
Joined: Nov 2006
Posts: 60
Likes: 0
From: Lacey, WA
Originally Posted by Patrick G
Check to see if your cat protection mode is dumping fuel. Many pcms will dump fuel to protect cats at higher rpm. My 2007 Suburban did it. After we fixed that, we gained close to 30 rwhp.
What are the options for monitoring AFR while driving?
-Dan
TECH Fanatic
Joined: Jan 2006
Posts: 1,050
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From: reading,pa
If you have headers, just get your brother's squirt gun and hit the primaries while hot. The difference in steam will be obvious, someone on here posted. I've never tried it, and I'd think they would all be so hot it wouldn't mantter, but that's what I've heard to do.
