STS troubleshooting help
06-03-2006, 06:41 AM
#1
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STS troubleshooting help Car pulled pretty good to ~5200 rpms then the horsepower (400rwhp)flattened out and gained nothing on all the dyno runs. We are stumped. Driveability is excellent. Here are the details.
2001 Chevrolet Corvette
Completely stock
29,000 miles
Automatic
3.15 rear axle ratio
perfect running condition
Mobil 1 engine oil
Royal purple Max ATF
No trouble codes
No dyno runs or ever raced before this.
Added:
NGK TR6ix iridium plugs gapped at .035
MSD plug wires
160F thermostat
Comp Cams 918 valve springs
Comp hardened pushrods stock length
STS C5 twin kit
GT32 upgrade
.4 bar spring
STS airbridge
Motron 60lb injectors
Bassani off road pipe (eliminates cats)
Bassani X-pipe
custom tuning
81 degrees F outside
Oil temps never went over 205F
Transmission temps never went over 200F
Fuel Pressure was good
Boost (near brake master) and Air/Fuel (tailpipe) were recorded
10 dyno runs with all having similar power curves.
Torque Converter locked.
We changed the air/fuel from 10.5-11.9 with no effect on horsepower output because of flattened horspower curve. Boost peaked at about 6.3 psi. All recorded parameters were normal..no knock retard...good fuel trims...15 degrees timing
What do you guys make at 5000rpms? I was 400hp/415tq but it was flat from there up. Looks like valve float but can it be with the 918s?
Thanks for any help. I can email you a video but its not all that great...I was waiting for a good run but it never happened! I love the sound...you have to hear it in person.
http://pg.photos.yahoo.com/ph/man77k...e2.jpg&.src=ph
2001 Chevrolet Corvette
Completely stock
29,000 miles
Automatic
3.15 rear axle ratio
perfect running condition
Mobil 1 engine oil
Royal purple Max ATF
No trouble codes
No dyno runs or ever raced before this.
Added:
NGK TR6ix iridium plugs gapped at .035
MSD plug wires
160F thermostat
Comp Cams 918 valve springs
Comp hardened pushrods stock length
STS C5 twin kit
GT32 upgrade
.4 bar spring
STS airbridge
Motron 60lb injectors
Bassani off road pipe (eliminates cats)
Bassani X-pipe
custom tuning
81 degrees F outside
Oil temps never went over 205F
Transmission temps never went over 200F
Fuel Pressure was good
Boost (near brake master) and Air/Fuel (tailpipe) were recorded
10 dyno runs with all having similar power curves.
Torque Converter locked.
We changed the air/fuel from 10.5-11.9 with no effect on horsepower output because of flattened horspower curve. Boost peaked at about 6.3 psi. All recorded parameters were normal..no knock retard...good fuel trims...15 degrees timing
What do you guys make at 5000rpms? I was 400hp/415tq but it was flat from there up. Looks like valve float but can it be with the 918s?
Thanks for any help. I can email you a video but its not all that great...I was waiting for a good run but it never happened! I love the sound...you have to hear it in person.
http://pg.photos.yahoo.com/ph/man77k...e2.jpg&.src=ph
06-03-2006, 10:43 AM
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what A/R is your turbo. my dyno graph looks identical to yours and i just found out sts sent me a gt67 with a .96 A/R, its to big for my car so at high rpm my eng doesnt spin turbo efficiently. they are sending me a .81 A/R. Brandon at sts told me it would make a world of diffence on the dyno and while driving.
06-03-2006, 12:52 PM
#5
Originally Posted by smoke20
what A/R is your turbo. my dyno graph looks identical to yours and i just found out sts sent me a gt67 with a .96 A/R, its to big for my car so at high rpm my eng doesnt spin turbo efficiently. they are sending me a .81 A/R. Brandon at sts told me it would make a world of diffence on the dyno and while driving.
It's a twin setup so it's a different ball game. *subscribes to thread*
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06-03-2006, 06:36 PM
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Originally Posted by HolyShiznit
It's a twin setup so it's a different ball game. *subscribes to thread*
06-04-2006, 12:20 AM
#10
Originally Posted by smoke20
i didnt see it was twin turbo , my bad , just for my info , why would the A/R not be important on a twin but it is on a single ?????
Because in theory the single will have bigger A/R's as compared to the twins and thus I am assuming it's not the problem. Single kits usually use one larger sized turbo and the twins use two smaller turbos.
06-04-2006, 01:04 AM
#11
GT32 A/R = .78, each unit is good for 420bhp or ~336rwhp w/ choke line at 40lb/min. A 346 requires about 52lb/min. at 5500rpm.
Does the STS twin kit come with some type of IC? Your charge temp. could have been too hot but realistically, at 6psi your increase in power seems about average. A stock automatic C5 is about 280-290 on an average wheel dyno. So you made between 110-120rwhp. Turn it up to 10lbs. with the proper tune and see what your get.
Does the STS twin kit come with some type of IC? Your charge temp. could have been too hot but realistically, at 6psi your increase in power seems about average. A stock automatic C5 is about 280-290 on an average wheel dyno. So you made between 110-120rwhp. Turn it up to 10lbs. with the proper tune and see what your get.
Last edited by NOSjohn; 06-04-2006 at 01:13 AM.
06-04-2006, 06:57 AM
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Originally Posted by speedz06
I was thinking springs too but I want to see fuel preassure,throttle position(you never know)did you do a base dyno run and did it have the same problem?
As I stated in the first post...918 springs were used
06-04-2006, 06:59 AM
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Originally Posted by NOSjohn
GT32 A/R = .78, each unit is good for 420bhp or ~336rwhp w/ choke line at 40lb/min. A 346 requires about 52lb/min. at 5500rpm.
Does the STS twin kit come with some type of IC? Your charge temp. could have been too hot but realistically, at 6psi your increase in power seems about average. A stock automatic C5 is about 280-290 on an average wheel dyno. So you made between 110-120rwhp. Turn it up to 10lbs. with the proper tune and see what your get.
Does the STS twin kit come with some type of IC? Your charge temp. could have been too hot but realistically, at 6psi your increase in power seems about average. A stock automatic C5 is about 280-290 on an average wheel dyno. So you made between 110-120rwhp. Turn it up to 10lbs. with the proper tune and see what your get.
Typical is 450-480rwhp on C5 autos at 6psi.
06-04-2006, 08:37 AM
#14
You have a leak at some point in either the hot side or charge side piping or your w/g or b.ov. is not working correctly. Put some wheel bearing grease near the end of the fittings or something of similar consistancy so once under boost you can see if there is air disturbance near the fitting (on the charge side). You can do this for a few minutes, if you run the car or drive it for any length of time, the charge side will get warm as well. Normally check the charge side first, hot side will be a little tougher to troubleshoot. But make sure to check both. You might be bleeding boost off.
06-04-2006, 09:39 AM
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Originally Posted by NOSjohn
You have a leak at some point in either the hot side or charge side piping or your w/g or b.ov. is not working correctly. Put some wheel bearing grease near the end of the fittings or something of similar consistancy so once under boost you can see if there is air disturbance near the fitting (on the charge side). You can do this for a few minutes, if you run the car or drive it for any length of time, the charge side will get warm as well. Normally check the charge side first, hot side will be a little tougher to troubleshoot. But make sure to check both. You might be bleeding boost off.
06-04-2006, 11:33 AM
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I had the same problem once with my STS single... yes it will hold 6psi but it may be bleeding off air heavy. Check all of your fittings. Normally your hot side should not be your problem unless your having spooling problems as well. Do you drop PSI at 5k rpms?
