Bad dyno numbers?
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I have an 04+ LS1
H-beam rods, diamond -2cc pistons
edelbrock performer carb intake
proform 750 race carb
MSD 6LS
ATI super dampener, no underdrive
no accesories other than waterpump and alt.
stock 241 heads
PRC dual springs with chromoly 7.425 Push rods, LS7 lifters
Pat G spec'd cam: 226/230 .598”/.600” 111LSA +4 advance
TKO500 5 spd
3.50 ford 9" rear end
Block was build by texas Speed so i dont think there is anything wrong with that.
Valvetrain was installed per standard installation instructions, should I have done anything different for PR install?
here is the potential weak link
crappy ebay shorty headers...., no cats
I was expecting somewhere @ 400whp
The A/F was @ 12.45
Best run once it was all tuned was 338hp/331tq
It was on a dynojet dyno
that seems low.. thoughts?
could the crappy headers really be losing THAT much?
What could be wrong? cam timing? could the lower compression of -2cc pistons lose THAT much power?
H-beam rods, diamond -2cc pistons
edelbrock performer carb intake
proform 750 race carb
MSD 6LS
ATI super dampener, no underdrive
no accesories other than waterpump and alt.
stock 241 heads
PRC dual springs with chromoly 7.425 Push rods, LS7 lifters
Pat G spec'd cam: 226/230 .598”/.600” 111LSA +4 advance
TKO500 5 spd
3.50 ford 9" rear end
Block was build by texas Speed so i dont think there is anything wrong with that.
Valvetrain was installed per standard installation instructions, should I have done anything different for PR install?
here is the potential weak link
crappy ebay shorty headers...., no cats
I was expecting somewhere @ 400whp
The A/F was @ 12.45
Best run once it was all tuned was 338hp/331tq
It was on a dynojet dyno
that seems low.. thoughts?
could the crappy headers really be losing THAT much?
What could be wrong? cam timing? could the lower compression of -2cc pistons lose THAT much power?
Last edited by eric1h; 11-26-2009 at 07:00 AM.
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not stock manifolds, short headers per above, dynojet dyno.
Went with shorty headers because the car has side exhaust and noone makes a long tube header. the shortys are temporary, I wanted to get the swap done first and then I'll work on a set of custom long tubes...
The last LS1 I had on the dyno, same year, but with stock internals and same carb/intake manifold setup made 326whp with NO oil pressure(don't ask)
Went with shorty headers because the car has side exhaust and noone makes a long tube header. the shortys are temporary, I wanted to get the swap done first and then I'll work on a set of custom long tubes...
The last LS1 I had on the dyno, same year, but with stock internals and same carb/intake manifold setup made 326whp with NO oil pressure(don't ask)
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Only things I can think would be wrong...
1. for some reason the cam timing is off(but i did install the cam per the timing dots and instructions, spun the crank a few times to verify they were till lined up)
2. too much preload on the valves? maybe holding them open a little? but i would think the car would rough like crap and not pull any vacuum
3. could have been WAYY to much oil?
I have 13Qts of oil in the car, 7 for pan, 1 for filter, 2 for oil lines and cooler, and 3 for accusump.
When i arrived at the dyno shop the valve was closed so I dont know if all the oil from the accusump was in the pan or where it should be.
1. for some reason the cam timing is off(but i did install the cam per the timing dots and instructions, spun the crank a few times to verify they were till lined up)
2. too much preload on the valves? maybe holding them open a little? but i would think the car would rough like crap and not pull any vacuum
3. could have been WAYY to much oil?
I have 13Qts of oil in the car, 7 for pan, 1 for filter, 2 for oil lines and cooler, and 3 for accusump.
When i arrived at the dyno shop the valve was closed so I dont know if all the oil from the accusump was in the pan or where it should be.
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#8
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A printout of the dyno sheet would show if it was funky cam timing or not.
Your problem is more likely carb not opening up all the way at WOT (vacuum secondaries?) or your motor is losing spark in one cylinder. Pull every plug wire and verify continuity and proper resistance. Use a timing light to verify spark at each plug or use an infrared temp sensor to see if you have a dead hole. This is more common than you might think, especially if you're running MSD coils or wires.
Your problem is more likely carb not opening up all the way at WOT (vacuum secondaries?) or your motor is losing spark in one cylinder. Pull every plug wire and verify continuity and proper resistance. Use a timing light to verify spark at each plug or use an infrared temp sensor to see if you have a dead hole. This is more common than you might think, especially if you're running MSD coils or wires.
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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.
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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.
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A printout of the dyno sheet would show if it was funky cam timing or not.
Your problem is more likely carb not opening up all the way at WOT (vacuum secondaries?) or your motor is losing spark in one cylinder. Pull every plug wire and verify continuity and proper resistance. Use a timing light to verify spark at each plug or use an infrared temp sensor to see if you have a dead hole. This is more common than you might think, especially if you're running MSD coils or wires.
Your problem is more likely carb not opening up all the way at WOT (vacuum secondaries?) or your motor is losing spark in one cylinder. Pull every plug wire and verify continuity and proper resistance. Use a timing light to verify spark at each plug or use an infrared temp sensor to see if you have a dead hole. This is more common than you might think, especially if you're running MSD coils or wires.
Also a good idea to check the wires, but we did pull all the plugs and check them I would think a dead wire/coil would show up as way rich on that plug.
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If it's a vacuum secondary carb, then that's the most likely reason for the soft numbers. You may need to subsitute a lighter spring for the secondaries so they open up all the way at WOT. You may only be operating on 2 bbls (plus a little bit of your rear 2).
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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.
![](https://ls1tech.com/forums/signaturepics/sigpic210_1.gif)
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.
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I have an open track/testn tune on Monday I am going to do the paperclip trick to see if the secondaries are opening all the way or how much, so hopefully that will tell us!
I am also looking to see if I can convert the carb to a mechanical secondary
I am also looking to see if I can convert the carb to a mechanical secondary
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Well with a different pan and whatnot, its' probably different, but using the dipstick is always a good way to check the oil level. It also probably isn't helping that you exhaust appears to be crimped down to the same size at you header primaries where it turns for the side exhaust.
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The Oil pan is a moroso 7qt pan, the exhaust is mandrel bent where it exits the shorty headers, not crimped.
I think Patrick may be on to something with the vacuum secondaries, going to test this Monday
I think Patrick may be on to something with the vacuum secondaries, going to test this Monday
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All that aside, I know how to use a dipstick, the problem was, I wasnt there when they ran the dyno, and when i start the car i flip the switch for the accusump, so I dont know what the oil level was when they dyno'd the car...
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like said, 7qts for pan, 3 qts for accusump, I have 10+ feet of Oil lines, Plus the oil cooler is good for a quart... Also, I don't have a standard LS1 oil filter, its a MUCH larger oil filter.... the oil level is right when the accusump has filled with oil, the problem is when you leave the valve open and shut off the car, and then later shut the switch off leavng all the oil in the pan
All that aside, I know how to use a dipstick, the problem was, I wasnt there when they ran the dyno, and when i start the car i flip the switch for the accusump, so I dont know what the oil level was when they dyno'd the car...
All that aside, I know how to use a dipstick, the problem was, I wasnt there when they ran the dyno, and when i start the car i flip the switch for the accusump, so I dont know what the oil level was when they dyno'd the car...
for an example, my 98 z28 is sts outfitted, but sts only calls for an extra 1/2 a quart, = to 6 and 1/2 quarts because its a stock ls1, and i know damn well the oil lines going all the way back to the rear of the car and then back up plus whats in the turbo are way more than 1/2 a quart. hope this helps!!
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