5.3 Thirdgen, New cam, Heads, and Dyno Tune.. I think i lost power
05-16-2015, 07:08 PM
#1
5.3 Thirdgen, New cam, Heads, and Dyno Tune.. I think i lost power Hey guys, having some issues with my LM7 swapped Thirdgen. First, my old setup and numbers. Motor is a 2003 LM7 5.3, bought it with 89,000 miles a year and a half ago. I put it together and dropped it in my Camaro with the following:
Stock Felpro head gaskets
Stock untouched 706 heads
1998 Camaro .500 lift LS1 cam
LS6 intake
Stock LS1 fuel rail, injectors, and throttle body
4th gen Camaro exhaust manifolds
3 inch exhaust after the manifolds through a magna flow muffler, no cats.
4th gen rear end with 3.42 gears
Tuned on 87 octane pump gas
This setup yielded 308RWHP and 323 RWTQ a year and a half ago. Was tuned on a dynojet by a reputable tuning shop. Was tuned in the winter, intake air temp was around 65 degrees shop temp.
I few months later i ditched the manifolds for a set of eBay stainless long-tube headers, and started using 93 octane pump gas. I also moved the air filter from under the hood to outside the engine bay, as well as the AIT sensor.Brought the car back to the tuner for an update on the tune, I believe around July, I know it was a humid day though. After the retune i was told the car ALMOST made as much power as last time. I know intake temp and humidity play a part, but i thought the long-tubes alone were good for 20RWHP, plus the 93 octane. Anyway i he didn't give me a dyno sheet, i just kind of forgot about it and kept enjoying the car because it was still quick.
Sorry this is a long post, i just don't want to be of those people that leaves out important details and keeps everyone asking questions, SO now for the latest..
A few months ago when i took the car out of winter storage i installed a FAST 102 intake and eBay 102 throttle body. Didn't go back for a retune, but man, even after having the ls6 intake, the fast definitely made the car breath better. It felt like the car gained some low end, and it didn't feel like it was heat soaking when it was warmed up like the ls6 intake felt. Drove like that for a few months, then last week i started doing some real work.
I picked up a set of low mileage 799 heads off eBay, and had them milled .030 to bring compression back up. I know they flow a little better, so for the 300 bucks i paid in all, i thought it be worth it. Setup now;
2009 799 heads, milled .030 for 9.6:1 Compression
Ls2 timing chain
Comp trunnion upgrade
Brian Tooley Racing .650 dual valve springs
Comp chromoly push rods, 7.350, measured to 0 lash with .75 preload
Comp Cams LSR 277 HR12, 227/235, .614/.621 113 lsa, 4.8/5.3 cam
LS7 Lifters
Fast 102 intake and 102 throttle body
Ebay stainless longtube headers, 3 inch piping and a flowmaster 10 series.
NGK iridium plugs.
The tuner had the car since 8:00 am monday, i TOOK it back friday evening because usually a tune only takes a day, and i needed the car. He said the car was drivable and the tune was safe, he just had to drive it on the street and fix a problem with the rpm not dropping sometimes after a shift. Other than that said it pulled like a ****, and I'm suppose to make an appointment for him to just fix the rpm issue.
I didn't get a dyno sheet, he said he's gonna email them to me. I was TOLD the car came in making 245rwhp and after the tune it put down 335RWHP. The car is much louder with the cam, but man it doesn't feel faster. It feels how it did before i put the LSX intake on. Plus how did i only get, at most, an extra 28rwhp with those upgrades? I think the tune is $hit to be honest, but could it be an issue with my combo? I wish i had a dyno sheet to show you guys, but i just can't wrap my head around how awful the car feels. I don't even want to drive it. Its loud for no reason, feels like a Honda
Also 75% of the time when i come to a stop the car stalls, and 100% of the time i do a WOT pull in 1st, then let off the gas, the rpm comes down past idle and dies. Everytime....
Stock Felpro head gaskets
Stock untouched 706 heads
1998 Camaro .500 lift LS1 cam
LS6 intake
Stock LS1 fuel rail, injectors, and throttle body
4th gen Camaro exhaust manifolds
3 inch exhaust after the manifolds through a magna flow muffler, no cats.
4th gen rear end with 3.42 gears
Tuned on 87 octane pump gas
This setup yielded 308RWHP and 323 RWTQ a year and a half ago. Was tuned on a dynojet by a reputable tuning shop. Was tuned in the winter, intake air temp was around 65 degrees shop temp.
I few months later i ditched the manifolds for a set of eBay stainless long-tube headers, and started using 93 octane pump gas. I also moved the air filter from under the hood to outside the engine bay, as well as the AIT sensor.Brought the car back to the tuner for an update on the tune, I believe around July, I know it was a humid day though. After the retune i was told the car ALMOST made as much power as last time. I know intake temp and humidity play a part, but i thought the long-tubes alone were good for 20RWHP, plus the 93 octane. Anyway i he didn't give me a dyno sheet, i just kind of forgot about it and kept enjoying the car because it was still quick.
Sorry this is a long post, i just don't want to be of those people that leaves out important details and keeps everyone asking questions, SO now for the latest..
A few months ago when i took the car out of winter storage i installed a FAST 102 intake and eBay 102 throttle body. Didn't go back for a retune, but man, even after having the ls6 intake, the fast definitely made the car breath better. It felt like the car gained some low end, and it didn't feel like it was heat soaking when it was warmed up like the ls6 intake felt. Drove like that for a few months, then last week i started doing some real work.
I picked up a set of low mileage 799 heads off eBay, and had them milled .030 to bring compression back up. I know they flow a little better, so for the 300 bucks i paid in all, i thought it be worth it. Setup now;
2009 799 heads, milled .030 for 9.6:1 Compression
Ls2 timing chain
Comp trunnion upgrade
Brian Tooley Racing .650 dual valve springs
Comp chromoly push rods, 7.350, measured to 0 lash with .75 preload
Comp Cams LSR 277 HR12, 227/235, .614/.621 113 lsa, 4.8/5.3 cam
LS7 Lifters
Fast 102 intake and 102 throttle body
Ebay stainless longtube headers, 3 inch piping and a flowmaster 10 series.
NGK iridium plugs.
The tuner had the car since 8:00 am monday, i TOOK it back friday evening because usually a tune only takes a day, and i needed the car. He said the car was drivable and the tune was safe, he just had to drive it on the street and fix a problem with the rpm not dropping sometimes after a shift. Other than that said it pulled like a ****, and I'm suppose to make an appointment for him to just fix the rpm issue.
I didn't get a dyno sheet, he said he's gonna email them to me. I was TOLD the car came in making 245rwhp and after the tune it put down 335RWHP. The car is much louder with the cam, but man it doesn't feel faster. It feels how it did before i put the LSX intake on. Plus how did i only get, at most, an extra 28rwhp with those upgrades? I think the tune is $hit to be honest, but could it be an issue with my combo? I wish i had a dyno sheet to show you guys, but i just can't wrap my head around how awful the car feels. I don't even want to drive it. Its loud for no reason, feels like a Honda
Also 75% of the time when i come to a stop the car stalls, and 100% of the time i do a WOT pull in 1st, then let off the gas, the rpm comes down past idle and dies. Everytime....
05-17-2015, 05:42 PM
#3
Moderator
Do you have a wideband O2 sensor on it? Ideally a wideband gauge?
Did the tuner hook up a wideband O2 sensor? If not, install one and find another tuner that will use it. Your stalling issue indicates a bad tune; your cam isn't that wild and IMHO any competent tuner should have a repertoire of Idle tables to handle that cam.
Just a wild guess - perhaps your fuel system has insufficient capacity and you are running lean at WOT. The tuner noticed the knock and reduced the timing unnecessarily. So you are both lean and have minimal ignition advance. Just a wild guess.
Start the with wideband. I keep on eye on my WB gauges at WOT to be sure I am not running lean for any reason.
Did the tuner hook up a wideband O2 sensor? If not, install one and find another tuner that will use it. Your stalling issue indicates a bad tune; your cam isn't that wild and IMHO any competent tuner should have a repertoire of Idle tables to handle that cam.
Just a wild guess - perhaps your fuel system has insufficient capacity and you are running lean at WOT. The tuner noticed the knock and reduced the timing unnecessarily. So you are both lean and have minimal ignition advance. Just a wild guess.
Start the with wideband. I keep on eye on my WB gauges at WOT to be sure I am not running lean for any reason.
05-17-2015, 08:16 PM
#4
Do you have a wideband O2 sensor on it? Ideally a wideband gauge?
Did the tuner hook up a wideband O2 sensor? If not, install one and find another tuner that will use it. Your stalling issue indicates a bad tune; your cam isn't that wild and IMHO any competent tuner should have a repertoire of Idle tables to handle that cam.
Just a wild guess - perhaps your fuel system has insufficient capacity and you are running lean at WOT. The tuner noticed the knock and reduced the timing unnecessarily. So you are both lean and have minimal ignition advance. Just a wild guess.
Start the with wideband. I keep on eye on my WB gauges at WOT to be sure I am not running lean for any reason.
Did the tuner hook up a wideband O2 sensor? If not, install one and find another tuner that will use it. Your stalling issue indicates a bad tune; your cam isn't that wild and IMHO any competent tuner should have a repertoire of Idle tables to handle that cam.
Just a wild guess - perhaps your fuel system has insufficient capacity and you are running lean at WOT. The tuner noticed the knock and reduced the timing unnecessarily. So you are both lean and have minimal ignition advance. Just a wild guess.
Start the with wideband. I keep on eye on my WB gauges at WOT to be sure I am not running lean for any reason.
Looking on there site, under the info for the cam it says "Must have substantial airflow upgrades, inlet & exhaust." Im running the Fast intake, tb, and longtubes, But do you think the stock flowing 799 heads could be a restriction for this cam and contributing to the tuning issue?
05-17-2015, 10:03 PM
#5
Not likely the problem but did the cam come with a stall/gears recommendation? Nothing makes a car fell like a turd than a big cam with a stock converter and wrong gear ratio.
05-18-2015, 09:30 AM
#6
This pretty much explains everything in my eyes. A properly tuned car won't die for no reason. If you had said the car dies when you come to a stop then I would have suggested you look at the converter/cam combo but if it dies after a wide open pull then I would look at the tune.
Not likely the problem but did the cam come with a stall/gears recommendation? Nothing makes a car fell like a turd than a big cam with a stock converter and wrong gear ratio.
Not likely the problem but did the cam come with a stall/gears recommendation? Nothing makes a car fell like a turd than a big cam with a stock converter and wrong gear ratio.