Well most of you don't know, Gary sold his Twin Turbo C6 a few months back, shortly after being the first person to have LAPD install the kit on his car. I picked it up from him here in Vegas, and shortly afterwards the number 7 piston broke up and there went my motor. Apparently the car was running lean, probably due to the stock fuel pump letting go, since it did go out right before the piston let go. Long story short NRP here at the Las Vegas Motor Speedway just built me a fully forged stroked 402. Custom JE turbo pistons, callies crankshaft, all the goodies. Well now that the motor is broken in I just had it tuned today. We could not get it to hit more than 8 PSI of boost maybe 8.5 here and there. He says he thinks the turbos are winded and they can't handle all the extra air the motor is pumping through. He is also unsure on what size the turbos are, I thought they might be GT30's but wasn't sure, he said they looked too small to be 30s, since he has 30s at his shop and was trying to compare them to mine , although it was hard with them on my car. He said they look more like GT28's, so I suppose my first question is what size Turbos does the APS kit come with? My second question is I thought I remember someone with a built 427 and this turbo kit having the same type of problem, not being able to hold boost. He said something about upgraded actuators? Other than that the car is freakin awesome. They did a great job at NRP and Gil Nevarez is top notch when it comes to customer service. The car made 600 rwtq and 550 rwhp on 8 psi of boost. He said he built the motor for about 20 PSI, so I figured a number around 11-15 psi would be nice. If anyone can help with this issue it would be much appreciated.
I believe "Blocktrdr" has a APS 427ci combo.
Here is one of his posts below.
Quote:
Originally Posted by Blocktrdr
The turbos in the APS system are GT28 GT30 hybrids. I don't know if you could break 15 lbs on an LS2 with them. That would be alot of exhaust to go through the turbines. There may be an option real soon though.
Well most of you don't know, Gary sold his Twin Turbo C6 a few months back, shortly after being the first person to have LAPD install the kit on his car. I picked it up from him here in Vegas, and shortly afterwards the number 7 piston broke up and there went my motor. Apparently the car was running lean, probably due to the stock fuel pump letting go, since it did go out right before the piston let go. Long story short NRP here at the Las Vegas Motor Speedway just built me a fully forged stroked 402. Custom JE turbo pistons, callies crankshaft, all the goodies. Well now that the motor is broken in I just had it tuned today. We could not get it to hit more than 8 PSI of boost maybe 8.5 here and there. He says he thinks the turbos are winded and they can't handle all the extra air the motor is pumping through. He is also unsure on what size the turbos are, I thought they might be GT30's but wasn't sure, he said they looked too small to be 30s, since he has 30s at his shop and was trying to compare them to mine , although it was hard with them on my car. He said they look more like GT28's, so I suppose my first question is what size Turbos does the APS kit come with? My second question is I thought I remember someone with a built 427 and this turbo kit having the same type of problem, not being able to hold boost. He said something about upgraded actuators? Other than that the car is freakin awesome. They did a great job at NRP and Gil Nevarez is top notch when it comes to customer service. The car made 600 rwtq and 550 rwhp on 8 psi of boost. He said he built the motor for about 20 PSI, so I figured a number around 11-15 psi would be nice. If anyone can help with this issue it would be much appreciated.
I agree, it sounds an awful lot like a wastegate problem to me.
The turbos will be able to make 16psi on a 403ci motor. How do I know...I had a very similar kit (Incon) on a 403ci iron blocked LS1 motor with the same turbos. The car would quickly spike to 18 and then settle at 16psi in the upper rpms.
You can always try having the shop wire the wastegates shut when tuning and making a quick pull. This will tell you if the actuator is unable to hold the wastegate closed as exhaust pressure rises.
To be honest, I never had a problem with the internal gates on my Incon setup, I was running the stock internal wastegate setup at 16psi.
Scott, I see they are doing the finishing touches on your car...once she's done let's meet up with George (Silver C6 APS A4) he just took delivery of his car yesterday...lunch or something, I like to hear more about your turbo experiences.
Actually the max psi possible from the C6 APS TT setup is 20 psi. They are EACH good to 550 hp. The boost needs to be manually adjusted since I presume you don't have a MBC or EBC on the car. To max the turbo output, you obviously need to have forged components, stronger head bolts, a driveline that can handle that kind of power, sufficient fuel output and the 3" exhaust. 10-11 psi on a MN and 9 on a AT are about the most you can go. Now with a forged 402 like you have, as long as you've installed the stronger head bolts/gaskets, upgraded the trans and driveline you should be able to go all the way. All you've done is increase the stroke to get to 402 cubes so that will not cause you to lose 12 psi worth of capability. I agree with others on the wastegate sticking, or possibly your tuner does not understand the APS setup.
Last edited by bigsamsdad; 01-20-2007 at 08:10 PM.
Actually the max psi possible from the C6 APS TT setup is 20 psi. They are EACH good to 550 hp. The boost needs to be manually adjusted since I presume you don't have a MBC or EBC on the car. To max the turbo output, you obviously need to have forged components, stronger head bolts, a driveline that can handle that kind of power, sufficient fuel output and the 3" exhaust. 10-11 psi on a MN and 9 on a AT are about the most you can go. Now with a forged 402 like you have, as long as you've installed the stronger head bolts/gaskets, upgraded the trans and driveline you should be able to go all the way. All you've done is increase the stroke to get to 402 cubes so that will not cause you to lose 12 psi worth of capability. I agree with others on the wastegate sticking, or possibly your tuner does not understand the APS setup.
These turbos will not make 20psi on a 402 setup through the entire RPM range...even with the wastegates wired shut.
Richard, sounds good. I was hoping to have the car back this week, no such luck. Hopefully mid-week next week. I'll PM you and we can all get together. I will be in Hawaii week after next though for a little R&R.
yea thats what i think they r gt28's this turbo's r truely good for stock motor application like someone said its to much exhaust gases to pass through suck small turbo's. But if im not mistaken APS has bigger turbo's that have the same mounting size but r for more power. This happen to someone with the 350z he made almost 800rwhp but had to upgrade turbo's. He had the APS kit If im not mistaken the vette and Z and GTO bring the same size turbo's i guess its a good choice for stock application spools up quick and creates nice numbers. If i were you call APS they r closed for sometime but should be back soon talk to the and tell them about your problem. One thing though could be the actuators if im not wrong they sell upgraded actuators to make more boost and hold it. Hope this helps.
But again your best bet is to talk to them and they will tell you all you need to know.
Actually the max psi possible from the C6 APS TT setup is 20 psi. They are EACH good to 550 hp. The boost needs to be manually adjusted since I presume you don't have a MBC or EBC on the car. To max the turbo output, you obviously need to have forged components, stronger head bolts, a driveline that can handle that kind of power, sufficient fuel output and the 3" exhaust. 10-11 psi on a MN and 9 on a AT are about the most you can go. Now with a forged 402 like you have, as long as you've installed the stronger head bolts/gaskets, upgraded the trans and driveline you should be able to go all the way. All you've done is increase the stroke to get to 402 cubes so that will not cause you to lose 12 psi worth of capability. I agree with others on the wastegate sticking, or possibly your tuner does not understand the APS setup.
Okay, thats what I thought as far as capability of the turbos, someone told me they should produce 17 PSI pretty comfortably. What do you mean by MANUALLY ADJUSTED, do you mean by manually adjusting the Wastegate Arms?, something I don't understand by the way? What is an actuator? You say it opens the wastegate, so it sounds like maybe if theres too much pressure on it that it might GIVE and be too weak to keep the wastegate closed, therefore bleeding off the boost? Right or Wrong? It seems I spiked around 9.5 psi, I remember Gary saying that LAPD installed 9 PSI actuator springs, I told my tuner I wanted to tune it at about 11psi to just run around in everyday. So is he able to do that without having a boost controller hooked up? Can he just hook a Manual controller up to it fairly quickly to tune it on the dyno? Also I'm not exactly sure how a boost controller controls the boost? Does it somehow control the wastegates? Would throwing a boost controller on allow me to set it to 11 psi and hold boost? I'm not sure if he exactly understands the APS setup, because I did ask him if I got a boost controller if it would fix my problem and he said no. So again I am assuming that he somehow did something when he tuned it to try and tune it at a higher boost level. I am new to the TURBO scene, my last car was a Vortech supercharged Z06, I understand the basic principals of what turbos do but not all the details. And yes we did hardened head studs, and some kind of Kinetix head gaskets, not sure if that's spelled right but that's what it sounds like.
These turbos will not make 20psi on a 402 setup through the entire RPM range...even with the wastegates wired shut.
Richard, sounds good. I was hoping to have the car back this week, no such luck. Hopefully mid-week next week. I'll PM you and we can all get together. I will be in Hawaii week after next though for a little R&R.
I agree that the turbos will not make 20 psi through the entire RPM range. I stated that the max psi from the setup is 20 psi, not through the entire range. Turbos typically spool up to max psi to the maximum part of the power curve then back off a bit to a slightly lower level. Here is the APS graph for the psi range of the stock LS2 for those that are curious. It's the second graph down. You can see that the boost starts at 3 psi, ramps to 10.5 then backs off to 9.
Okay, thats what I thought as far as capability of the turbos, someone told me they should produce 17 PSI pretty comfortably. What do you mean by MANUALLY ADJUSTED, do you mean by manually adjusting the Wastegate Arms?, something I don't understand by the way? What is an actuator? You say it opens the wastegate, so it sounds like maybe if theres too much pressure on it that it might GIVE and be too weak to keep the wastegate closed, therefore bleeding off the boost? Right or Wrong? It seems I spiked around 9.5 psi, I remember Gary saying that LAPD installed 9 PSI actuator springs, I told my tuner I wanted to tune it at about 11psi to just run around in everyday. So is he able to do that without having a boost controller hooked up? Can he just hook a Manual controller up to it fairly quickly to tune it on the dyno? Also I'm not exactly sure how a boost controller controls the boost? Does it somehow control the wastegates? Would throwing a boost controller on allow me to set it to 11 psi and hold boost? I'm not sure if he exactly understands the APS setup, because I did ask him if I got a boost controller if it would fix my problem and he said no. So again I am assuming that he somehow did something when he tuned it to try and tune it at a higher boost level. I am new to the TURBO scene, my last car was a Vortech supercharged Z06, I understand the basic principals of what turbos do but not all the details. And yes we did hardened head studs, and some kind of Kinetix head gaskets, not sure if that's spelled right but that's what it sounds like.
Again thanks for the help
Your tuner needs to adjust the psi of the system. When using a manual or electronic boost controller, you adjust the boost of the system to the max output then manually or electronically dial it down as necessary. You also may need more fuel to accommodate the cubes and the boost increase. I do not know how to run the calculation myself but APS makes a high output fuel system that is required to maximize the output of the turbos. Also I believe that you will need to have the car retuned with the HP Tuners software that should currently be on the car. I don't think you can simply turn the boost up without retuning the car but I don't know this for a fact. If your tuner isn't familiar with the APS system, I would suggest that you talk to LAPD or Peter at APS to get your answers.
Here are the install instructions and parts list, but they don't talk about adjustments.
I agree that the turbos will not make 20 psi through the entire RPM range. I stated that the max psi from the setup is 20 psi, not through the entire range. Turbos typically spool up to max psi to the maximum part of the power curve then back off a bit to a slightly lower level. Here is the APS graph for the psi range of the stock LS2 for those that are curious. It's the second graph down. You can see that the boost starts at 3 psi, ramps to 10.5 then backs off to 9.
Turbos that are properly sized for the application will not spike and then drop off...they will hold boost through the entire RPM range.
The APS turbos are sized very well for a stock cube system, but will run out of steam with bigger cubes.
Quote:
Originally Posted by bigsamsdad
When using a manual or electronic boost controller, you adjust the boost of the system to the max output then manually or electronically dial it down as necessary.
Differences of opinion here, but usually if you have a controller I will set the boost as low as possible using the wastegate and then let the controller do its job and use it to increase boost. If you max out the boost setting at the wastegate then you need to be aware that is always going to be the lowest boost setting that you can get. Personally I like letting the boost controller do it's job. Although, if the wastegate is incapable of holding the boost at a lower setting then adjustments will need to be made.
Last edited by Scott 98Z M6; 01-21-2007 at 09:51 PM.
We finished up tuning on a 06 402 APS car yesterday with a LPE 100 maf. On the stock motor we saw 5psi and with the boost controller maxed it only made 6. Now with the 402 and the boost controller maxed it would hit 10psi and fall down to 6psi from 4500+. I'm looking into getting 10psi accuators from Forged. I don't want any more mid range boost but would just like to hold 10psi until redline. Its a A6 car and its already making 630rwt.
Well most of you don't know, Gary sold his Twin Turbo C6 a few months back, shortly after being the first person to have LAPD install the kit on his car. I picked it up from him here in Vegas, and shortly afterwards the number 7 piston broke up and there went my motor. Apparently the car was running lean, probably due to the stock fuel pump letting go, since it did go out right before the piston let go. Long story short NRP here at the Las Vegas Motor Speedway just built me a fully forged stroked 402. Custom JE turbo pistons, callies crankshaft, all the goodies. Well now that the motor is broken in I just had it tuned today. We could not get it to hit more than 8 PSI of boost maybe 8.5 here and there.
Hi Peter, I'm not surprized that you're stuck at 8 PSI as the boost control actuators are designed to operate and control boost pressure to around 9 PSI max, that is without any form of electronic boost control.
How were you trying to increase the boost presure?
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402 Apstt C6 Help Stuck At 8 Psi
