sts turbo lag?
GM World Class, I can't feel any lag, STS intercooled here and I can hear it spoolin' just under 3K, full boost under 4K all the way to 6.5K redline. This is with a 67mm on a 347, Just make sure you size your set up properly based on your motor, your power goals, and vehicle usage. Also, STS kits seem to perform better on Auto transmissions, I have one. Having a higher stall really helps you spool quick
GM World Class, I can't feel any lag, STS intercooled here and I can hear it spoolin' just under 3K, full boost under 4K all the way to 6.5K redline. This is with a 67mm on a 347, Just make sure you size your set up properly based on your motor, your power goals, and vehicle usage. Also, STS kits seem to perform better on Auto transmissions, I have one. Having a higher stall really helps you spool quick
Don't have dyno #'s right now, north of 500whp, what size hot side are you using? That may be why your power falls off, and if you are sized correctly for your set-up it might be the lack of a higher stall converter. If all else is addressed your problem may be in your tune.
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Don't have dyno #'s right now, north of 500whp, what size hot side are you using? That may be why your power falls off, and if you are sized correctly for your set-up it might be the lack of a higher stall converter. If all else is addressed your problem may be in your tune.
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Verdad Gallardo Your A/R sounds fine as long as your not running high boost, I'm running the same one. I can hear my turbo start spooling a just under 3K. I know you don't lag but your power does fall. Short gears wont help you either, you need to put a load on the turbo by using longer gears. Have you had the car dyno tuned on a wideband? A dyno would give you clues on what the problem may be. I'm guessing there is a problem in your tune, BTW, are you still on the stock clutch? If so how many miles? A slipping clutch can cause power loss.
That dyno shows your car is dying off just under 5K. Before that though, the car looks very strong. Are you running the stock heads and cam? You may be choking the breathing of your motor on the top end. Your Air/Fuel ratio looks good through the whole pull.
Last edited by omore001; Oct 26, 2008 at 09:00 PM.
Your set up is perfect, you have all the right upgrades, I can't find any other reason why your power starts to fall off before 5K. I would try to thoroughly explain your situation to a reputable tuner who has experience with turbo's and LT1 and see if they can provide you with a breakdown to find out where your problem lies.
What is your spk plug gap at? Are you running an intercooler? Something looks wrong there maybe your pcm is pulling a lot of timing due to the 10 psi of boost. I am running the gt 67 at 7psi and it doesn't start to drop off until about 6100rpm and not as steep as yours.
105lbs means nothing without the installed height. On a stock head with a valve job, each valve would have to be checked and shimmed accordingly to achieve the same installed height and pressure. Some builders, may even over shim to achieve a 10-15 lb high pressure so after some use they hopefully settle at the designed installed seat pressure. Valvetrain to most is like talking turbos......
Its probably not a real good idea to compare lt1 spring pressures to ls1 guys knowledge either in general anyways. Lt1's may run a heavier valve/retainer,lock combo(many variables here)....easy solution is ask the builder. If they built the heads they should know valvetrain weight to establish a needed spring pressure for a given cam.
Oh, btw, the installed height pressure is only an idicator. The real information is the compressed pressure (over the nose) . As gear heads we get caught up in easy, or consistent checks. Installed height is just a check, based on experience with a given spring/valvetrain combo. If a spring can do 105 @1.8 and 345 at 550, and another can do 135 @1.8 and 345 @ 550, there is no big difference, and infact the first may make more power. The real question is the latter number. As builders, we get use dto some set parts and know that if spring a tests at 135 @1.8 then it will probably be 345 @ 550 so there is no real need to check it cause we built this 10 times before.
BACK on TOPIC, sorry......most off the shelf kits, spool very well, but thats primarily a get in the door deal, that wont make real big power numbers. It obviously takes time, experience and money to get a big hp turbo car to spool like a smaller turbo. 67 's spool well, but if you step up to a 76 or larger, you better have everything right.
Its probably not a real good idea to compare lt1 spring pressures to ls1 guys knowledge either in general anyways. Lt1's may run a heavier valve/retainer,lock combo(many variables here)....easy solution is ask the builder. If they built the heads they should know valvetrain weight to establish a needed spring pressure for a given cam.
Oh, btw, the installed height pressure is only an idicator. The real information is the compressed pressure (over the nose) . As gear heads we get caught up in easy, or consistent checks. Installed height is just a check, based on experience with a given spring/valvetrain combo. If a spring can do 105 @1.8 and 345 at 550, and another can do 135 @1.8 and 345 @ 550, there is no big difference, and infact the first may make more power. The real question is the latter number. As builders, we get use dto some set parts and know that if spring a tests at 135 @1.8 then it will probably be 345 @ 550 so there is no real need to check it cause we built this 10 times before.
BACK on TOPIC, sorry......most off the shelf kits, spool very well, but thats primarily a get in the door deal, that wont make real big power numbers. It obviously takes time, experience and money to get a big hp turbo car to spool like a smaller turbo. 67 's spool well, but if you step up to a 76 or larger, you better have everything right.
Last edited by 1320; Oct 26, 2008 at 11:53 PM.
105lbs means nothing without the installed height. On a stock head with a valve job, each valve would have to be checked and shimmed accordingly to achieve the same installed height and pressure. Some builders, may even over shim to achieve a 10-15 lb high pressure so after some use they hopefully settle at the designed installed seat pressure. Valvetrain to most is like talking turbos......
Its probably not a real good idea to compare lt1 spring pressures to ls1 guys knowledge either in general anyways. Lt1's may run a heavier valve/retainer,lock combo(many variables here)....easy solution is ask the builder. If they built the heads they should know valvetrain weight to establish a needed spring pressure for a given cam.
Oh, btw, the installed height pressure is only an idicator. The real information is the compressed pressure (over the nose) . As gear heads we get caught up in easy, or consistent checks. Installed height is just a check, based on experience with a given spring/valvetrain combo. If a spring can do 105 @1.8 and 345 at 550, and another can do 135 @1.8 and 345 @ 550, there is no big difference, and infact the first may make more power. The real question is the latter number. As builders, we get use dto some set parts and know that if spring a tests at 135 @1.8 then it will probably be 345 @ 550 so there is no real need to check it cause we built this 10 times before.
BACK on TOPIC, sorry......most off the shelf kits, spool very well, but thats primarily a get in the door deal, that wont make real big power numbers. It obviously takes time, experience and money to get a big hp turbo car to spool like a smaller turbo. 67 's spool well, but if you step up to a 76 or larger, you better have everything right.
Its probably not a real good idea to compare lt1 spring pressures to ls1 guys knowledge either in general anyways. Lt1's may run a heavier valve/retainer,lock combo(many variables here)....easy solution is ask the builder. If they built the heads they should know valvetrain weight to establish a needed spring pressure for a given cam.
Oh, btw, the installed height pressure is only an idicator. The real information is the compressed pressure (over the nose) . As gear heads we get caught up in easy, or consistent checks. Installed height is just a check, based on experience with a given spring/valvetrain combo. If a spring can do 105 @1.8 and 345 at 550, and another can do 135 @1.8 and 345 @ 550, there is no big difference, and infact the first may make more power. The real question is the latter number. As builders, we get use dto some set parts and know that if spring a tests at 135 @1.8 then it will probably be 345 @ 550 so there is no real need to check it cause we built this 10 times before.
BACK on TOPIC, sorry......most off the shelf kits, spool very well, but thats primarily a get in the door deal, that wont make real big power numbers. It obviously takes time, experience and money to get a big hp turbo car to spool like a smaller turbo. 67 's spool well, but if you step up to a 76 or larger, you better have everything right.
The question in and of itself is worthless without a lot more information than the OP provided.
I went and picked up a 2002 Z with a STS kit. Never had any lag problems, 5 psi was 400 and 8psi was 505 rwhp. It would make full spool in between 3000 and 3600 and all the way to 7g's. I don't think you would see to much lag on low psi IMO you would see lag at 12 and up.
Teching In
Joined: Oct 2008
Posts: 15
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From: Sandy UT
1999 Firebird T/A
4L60E
STS
FIC
Methanol
42#
Walbro 255
Miles 149.658
I purchase this car with 100.000 miles on it, and I installed our kit on it one week after buying the car. I noticed that runing 5 PSI of boost I would see full boost by 3300 RPM, and now I run 9 on the low side and 12 with meth on the high side, the 12 PSI is full boost at 3600 and 9 PSI is full on at 3500. Now I am runing the GT67mm with .81 A/R housing with stock stall, and stock motor.
I drove my buddy's SS Camaro with a popular twin turbo kit on it, and at 8 PSI was full boost at 3500 RPM so lag or no lag it was identical.
Here is one thing I would recomend, for those of you running our rear mount system, with an A/T call STS and purchase the .68 A/R housing. arround a month ago I got board and decided just for fun I would install a 68 on my kit, I did it took 30 mins, and took it out on the road, now this is not a good houing for the freeway pass from 80 to 120mph but man at a light from a dig with out power breaking for a boost launch is incredible.
I was lucky enough to catch a young kid in daddy's new GT500 at a red light. The light went green and I took off easy becuase he did not seem to care, well that changed we were head to head when we crossed the intersection, and I heard the sound of a cats tail being steped on, I knew he it was on. I did the same and nailed it, we were maybe 35mph when this happend so my car dropped into first and instently blew the tires free then shifted second still blowing tracktion, and finally the top of second I grabbed and was gone. During the first and second gear traction loss we where neck and neck, when I grabbed at the top of second I was pulling on him hard I road 3rd out to 5500 and let out, I was an easy 3 cars on him.
Now normally when I run these cars with my .81 A/R the Mustang gets the jump on me, about 1/2 a car length until I hit 3500 RPM, at which point I blow past them. With the .68 I could have easlily taken him from the hole shot if I could have grabbed the road.
This was with 265 45 16 in the rear z rated F1 good years. and 8 PSI of boost. Give it a shot he 68 runs around 300.00 but well worth it for the hole shot or light to light street racing.
4L60E
STS
FIC
Methanol
42#
Walbro 255
Miles 149.658
I purchase this car with 100.000 miles on it, and I installed our kit on it one week after buying the car. I noticed that runing 5 PSI of boost I would see full boost by 3300 RPM, and now I run 9 on the low side and 12 with meth on the high side, the 12 PSI is full boost at 3600 and 9 PSI is full on at 3500. Now I am runing the GT67mm with .81 A/R housing with stock stall, and stock motor.
I drove my buddy's SS Camaro with a popular twin turbo kit on it, and at 8 PSI was full boost at 3500 RPM so lag or no lag it was identical.
Here is one thing I would recomend, for those of you running our rear mount system, with an A/T call STS and purchase the .68 A/R housing. arround a month ago I got board and decided just for fun I would install a 68 on my kit, I did it took 30 mins, and took it out on the road, now this is not a good houing for the freeway pass from 80 to 120mph but man at a light from a dig with out power breaking for a boost launch is incredible.
I was lucky enough to catch a young kid in daddy's new GT500 at a red light. The light went green and I took off easy becuase he did not seem to care, well that changed we were head to head when we crossed the intersection, and I heard the sound of a cats tail being steped on, I knew he it was on. I did the same and nailed it, we were maybe 35mph when this happend so my car dropped into first and instently blew the tires free then shifted second still blowing tracktion, and finally the top of second I grabbed and was gone. During the first and second gear traction loss we where neck and neck, when I grabbed at the top of second I was pulling on him hard I road 3rd out to 5500 and let out, I was an easy 3 cars on him.
Now normally when I run these cars with my .81 A/R the Mustang gets the jump on me, about 1/2 a car length until I hit 3500 RPM, at which point I blow past them. With the .68 I could have easlily taken him from the hole shot if I could have grabbed the road.
This was with 265 45 16 in the rear z rated F1 good years. and 8 PSI of boost. Give it a shot he 68 runs around 300.00 but well worth it for the hole shot or light to light street racing.