Road Racing LS2 434 need help with HP numbers and hard start
11-23-2011, 03:14 AM
#1
Racer
Thread Starter
Road Racing LS2 434 need help with HP numbers and hard start
I have an 06 A6 road racing car with a ERL sleeved LS2 434, L92 West Coast ported heads, Comp Cams 231 Intake 247 exhaust 617 and 624 lift and 113 lobe centers, Vararam, LS7 Throttle Body and injectors, FAST 102MM intake, Melrose 1 7/8 headers, hi flow cats, stock Z06 Mufflers, It also has 3:15 gears and Quaife diff. The cam and other parts were choose with road racing in mind and a wide flat toque curve.
I put it on a Dynojet dyno today and I was surprised that the horsepower was only 466 and the torque is about 477. The torque and horsepower curves looked to be about what I expected but I thought horsepower would be over 500 even with the automatic. I kind of pieced the car together with left over stuff and the headers are 5 years old with some small dents and old cats. I was wondering if the old headers, cats and stock Z06 mufflers are holding me back. Also what about the throttle body? Anyone have comments or ideas?
In addition we can't make it start without cracking the throttle so my dyno guy drilled a small hole in throttle plate but we still need to crack the throttle just a bit to get it to start. Anyone have any ideas on this?
I put it on a Dynojet dyno today and I was surprised that the horsepower was only 466 and the torque is about 477. The torque and horsepower curves looked to be about what I expected but I thought horsepower would be over 500 even with the automatic. I kind of pieced the car together with left over stuff and the headers are 5 years old with some small dents and old cats. I was wondering if the old headers, cats and stock Z06 mufflers are holding me back. Also what about the throttle body? Anyone have comments or ideas?
In addition we can't make it start without cracking the throttle so my dyno guy drilled a small hole in throttle plate but we still need to crack the throttle just a bit to get it to start. Anyone have any ideas on this?
On all levels
11-23-2011, 11:09 AM
#6
Racer
Thread Starter
Good Feedback
Hey guys that you for the information. My tuner did admit that drilling was old school and he agreed it was low on horsepower and that it should idle. He thought it should be over 500 HP as well. I wonder if there is something wrong with the set up. This guy tunes lots and lots of LS motors and they have 3 dynos in their shop so its not like they have never done this before. Lets assume for a second he knows what he is doing. Does my set up seem OK? Like I said it's kind of thrown together with some leftover parts from my Z06 and some other stuff but it seems that they should all work. What about the LS7 injectors and TB? Can bad headers, old (hi flow) cats and Z06 exhaust restrict it that much.
Any info is helpful.
Any info is helpful.
11-23-2011, 11:11 AM
#7
Racer
Thread Starter
11-23-2011, 11:12 AM
#8
Le Mans Master
Member Since: May 2011
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St. Jude Donor '11-'12-'13-'14
I've never heard of melrose headers personally. What size is the x-pipe? Any chance the cats are clogged? I'm assuming a 3" xpipe since you have z06 mufflers
11-23-2011, 11:40 AM
#10
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Hey guys that you for the information. My tuner did admit that drilling was old school and he agreed it was low on horsepower and that it should idle. He thought it should be over 500 HP as well. I wonder if there is something wrong with the set up. This guy tunes lots and lots of LS motors and they have 3 dynos in their shop so its not like they have never done this before. Lets assume for a second he knows what he is doing. Does my set up seem OK? Like I said it's kind of thrown together with some leftover parts from my Z06 and some other stuff but it seems that they should all work. What about the LS7 injectors and TB? Can bad headers, old (hi flow) cats and Z06 exhaust restrict it that much.
Any info is helpful.
Any info is helpful.
Thats a start, then a datalog of the run as well as a copy of the tune posted up would be a great secondary option.
11-23-2011, 11:56 AM
#12
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Hey guys that you for the information. My tuner did admit that drilling was old school and he agreed it was low on horsepower and that it should idle. He thought it should be over 500 HP as well. I wonder if there is something wrong with the set up. This guy tunes lots and lots of LS motors and they have 3 dynos in their shop so its not like they have never done this before. Lets assume for a second he knows what he is doing.
11-23-2011, 12:05 PM
#13
Racer
Thread Starter
The x pipe is 3" as is the rest of the exhaust except the mufflers which as I am sure you know go down to 2.5" at the stock Z06 mufflers.
11-23-2011, 12:39 PM
#17
Racer
Thread Starter
I talked to my guy that put the motor in and he checked the cats, he could see right through them and said they looked clear so that is out.
I talked to my Dyno guys and they are back at it this AM. He said he thinks there is more power to be had. He also feels that it should be putting at least 525 to the ground even with the A6. Any suggestions for him on the hard start issue? I realize that he drilled the throttle plate and everyone is sure that is a mistake but he does have a second one sitting there that I brought him which is perhaps why he wanted to try it.
Is there a difference between an LS7 TB and an LS2 TB? I put the LS7 on the car but we still have the LS2 sitting there. What about the injectors I put the LS7 injectors in it.
I talked to my Dyno guys and they are back at it this AM. He said he thinks there is more power to be had. He also feels that it should be putting at least 525 to the ground even with the A6. Any suggestions for him on the hard start issue? I realize that he drilled the throttle plate and everyone is sure that is a mistake but he does have a second one sitting there that I brought him which is perhaps why he wanted to try it.
Is there a difference between an LS7 TB and an LS2 TB? I put the LS7 on the car but we still have the LS2 sitting there. What about the injectors I put the LS7 injectors in it.
11-23-2011, 01:25 PM
#18
Drifting
What compression are you at? (sorry if you already mentioned)
Need to post up a dyno graph with AFR, did they say anything about valve float? you either have enough injector or you don't, is the car going way lean in the upper rpm range?
Dave, do you offer mail order tunes j/k
11-23-2011, 03:22 PM
#19
Le Mans Master
Hard starting: if you recently swapped cams, check your cam position sensor. I've seen these get trashed from wiping down the inside of the front eng cover with solvent, cleaners etc.