STS Observations and Questions Inside - Other Dyno Sheets Please
03-07-2008, 09:14 PM
#1
STS Observations and Questions Inside - Other Dyno Sheets Please I have been working with geeteego on his 2004 GTO and he has passed on some info to me along the way of what others have said works and does not work. I see how the different theories of stock manifolds versus longtubes and alos wrapping the exhaust could work. This has all possibly been gone over before and I apologize, but this is somewhat new to me though I have tuned an STS GTO about 2 years ago and it seemed to be okay in relation to money spent, boost at the turbo and power made.
Keep in mind I have tuned quite a few turbo cars, single front mount and twin front mount. Recently I tuned an APS C5 Z06 that made 565 RWHP and 565 RWT on 7.5-8 PSI. Stock engine with only a 216/224 155 Crane cam. This past weekend I tuned a front mount F-body, and I do not recall all the specifics, but it had a built engine and made roughly 600 RWHP and 600 RWT on 8 PSI. Tuned an stock LS1 GTO with and APS and on 6.5-7 PSI made 500 RWHP.
So now I get into this GTO. Intercooled, built 364, ported LS6 heads, Edelbrock carb manifold, elbow, 90mm TB and so on. 9.5 PSI makes 500 RWHP and RWT. 11.5 PSI make 550 RWHP and RWT. The wastegate has a 12 PSI spring and I am using an EBoost2 to control the boost. On the 11.5 PSI runs the A/F was at 11.8-1 and 16* timing, no knock.
This leads me to these question and observations. Figuring that every pound of boost adds 6.7-7% horsepower over the base engine (going by Gale Banks theory of 1 bar doubles horsepower), I am getting a calculation that this engine without boost makes approx 315-320 RWHP. This number seems very low considering the heads, intake, larger reverse split can (234-232 114??). Not saying I agree with the cam and would prefer a 218/226 116, just what I am working with.
I am thinking longtubes, 3" into a Y to 4" to the turbo, but everyone says that stock manifolds and small pipes keep heat and velocity to help the rear turbo. This car has stock manifolds, 2.5" pipe from the passenger manifold to a high flow muffler then 2.5" to the turbo. The drivers side has a 2" pipe off the manifold kind of Y-d into the passenger 2.5" pipe. If that is the case, not saying it is not, then why build a killer engine when you are going to choke it down? I am going to remove the pipe from the muffler to the turbo and just tune the car naturally aspirated and see if I come to the 310-320 RWHP area I am calculating. I will keep the same exhaust and also keep the inlet intact.
I am just thinking that if a nice longtube and exhaust will help make an extra 70-80 RWHP throughout the RPM band or more on engine would be worth in the long run. This thing already barely spools as it is and hits full boost at 5000 RPM
so I can not picture it being any worse.
After the naturally aspirated test I am slo going to change cams and inspect to see if the cam is degreed properly as it does act to a point that it is off one tooth. Probably not, but just want to verify as I did not do the build.
I have seen other posts of STS cars that are similar to a point. Zombies combo I have looked through to a point in a thread or two. I look at the PSI versus the track times and MPH and it does not jive by normal turbo thought. This is what is in his sig:
10.13 @ 132.72 19 psi
To me 19 psi on a stock 325 RWHP engine should be making 740-750 RWHP. Even if this is measure at the turbo and there is 3 psi boost drop, it would still be 675-685 RWHP. It is an auto trans car with 1.4x 60's so it is hooking. Most guys with 475-525 RWHP run low 10's and 130ish MPH. I would think this car would run mis to low 9's. Not that 10.1 is nothing to sneeze at by any means.
I saw another making 500-ish RWHP on 10 PSI and a stock engine and that would equate to a 310-320 RWHP engine. Sorry but I can not recall the members name. I saw another post from longrange4u that made 700 RWHP on 14 PSI with a 408, auto and larger cam, but not sure if he has headers or manifolds.
Again, not knocking anyones car or product, just trying to understand it all. I would very much like to see Zombies as well as anyone elses dyno sheets as long as they have a lower compression engine in the 9.0 to 1 area, larger turbo and running 10 plus pounds of boost. If you have a comparison of stock manifolds to headers that would be great also. Please state the entire combo and intake pressure, not compressor housing pressure. C5 twin setups do not apply hear to be a true compariosn, but that info can not hurt.
I very much appreciate all and any info from folks and thanks in advance. I am trying to help out geeteego max out what he has and look forward to my test results to see if my theory playes out.
Thanks and sorry for the long post
Mike Norris
Keep in mind I have tuned quite a few turbo cars, single front mount and twin front mount. Recently I tuned an APS C5 Z06 that made 565 RWHP and 565 RWT on 7.5-8 PSI. Stock engine with only a 216/224 155 Crane cam. This past weekend I tuned a front mount F-body, and I do not recall all the specifics, but it had a built engine and made roughly 600 RWHP and 600 RWT on 8 PSI. Tuned an stock LS1 GTO with and APS and on 6.5-7 PSI made 500 RWHP.
So now I get into this GTO. Intercooled, built 364, ported LS6 heads, Edelbrock carb manifold, elbow, 90mm TB and so on. 9.5 PSI makes 500 RWHP and RWT. 11.5 PSI make 550 RWHP and RWT. The wastegate has a 12 PSI spring and I am using an EBoost2 to control the boost. On the 11.5 PSI runs the A/F was at 11.8-1 and 16* timing, no knock.
This leads me to these question and observations. Figuring that every pound of boost adds 6.7-7% horsepower over the base engine (going by Gale Banks theory of 1 bar doubles horsepower), I am getting a calculation that this engine without boost makes approx 315-320 RWHP. This number seems very low considering the heads, intake, larger reverse split can (234-232 114??). Not saying I agree with the cam and would prefer a 218/226 116, just what I am working with.
I am thinking longtubes, 3" into a Y to 4" to the turbo, but everyone says that stock manifolds and small pipes keep heat and velocity to help the rear turbo. This car has stock manifolds, 2.5" pipe from the passenger manifold to a high flow muffler then 2.5" to the turbo. The drivers side has a 2" pipe off the manifold kind of Y-d into the passenger 2.5" pipe. If that is the case, not saying it is not, then why build a killer engine when you are going to choke it down? I am going to remove the pipe from the muffler to the turbo and just tune the car naturally aspirated and see if I come to the 310-320 RWHP area I am calculating. I will keep the same exhaust and also keep the inlet intact.
I am just thinking that if a nice longtube and exhaust will help make an extra 70-80 RWHP throughout the RPM band or more on engine would be worth in the long run. This thing already barely spools as it is and hits full boost at 5000 RPM
so I can not picture it being any worse.After the naturally aspirated test I am slo going to change cams and inspect to see if the cam is degreed properly as it does act to a point that it is off one tooth. Probably not, but just want to verify as I did not do the build.
I have seen other posts of STS cars that are similar to a point. Zombies combo I have looked through to a point in a thread or two. I look at the PSI versus the track times and MPH and it does not jive by normal turbo thought. This is what is in his sig:
10.13 @ 132.72 19 psi
To me 19 psi on a stock 325 RWHP engine should be making 740-750 RWHP. Even if this is measure at the turbo and there is 3 psi boost drop, it would still be 675-685 RWHP. It is an auto trans car with 1.4x 60's so it is hooking. Most guys with 475-525 RWHP run low 10's and 130ish MPH. I would think this car would run mis to low 9's. Not that 10.1 is nothing to sneeze at by any means.
I saw another making 500-ish RWHP on 10 PSI and a stock engine and that would equate to a 310-320 RWHP engine. Sorry but I can not recall the members name. I saw another post from longrange4u that made 700 RWHP on 14 PSI with a 408, auto and larger cam, but not sure if he has headers or manifolds.
Again, not knocking anyones car or product, just trying to understand it all. I would very much like to see Zombies as well as anyone elses dyno sheets as long as they have a lower compression engine in the 9.0 to 1 area, larger turbo and running 10 plus pounds of boost. If you have a comparison of stock manifolds to headers that would be great also. Please state the entire combo and intake pressure, not compressor housing pressure. C5 twin setups do not apply hear to be a true compariosn, but that info can not hurt.
I very much appreciate all and any info from folks and thanks in advance. I am trying to help out geeteego max out what he has and look forward to my test results to see if my theory playes out.
Thanks and sorry for the long post
Mike Norris
03-07-2008, 11:19 PM
#2
Im with you mike,on a built bigger cube motor a real header setup makes sense.1 thing that might be a cheap thing to try is to throw a manual boost controller on it like i did.You remember the trouble i had with the Eboost 2.manual controllers are like $10 off ebay,hell i need to come back and see u now that my fuel issue is fixed anyways u can use mine.
03-07-2008, 11:55 PM
#3
Staging Lane
Join Date: Jan 2008
Location: Louisville, Ky Area
Posts: 64
Likes: 0
Received 0 Likes
on
0 Posts
Hey Mike...how ya been??
I can give you my own personal experience. About a year and a half ago, I built a rear mount GT45R turbo system on my '98 Formula A4. Engine was a factory LS6 with Edelbrock Intake, sheetmetal plenum, custom cam (roughly 230/240 @ .050 / .600ish Lift) and .072 thick Cometic headgaskets to lower the compression a bit. I was running 15lbs of boost and making 681rwhp/861rwtq. Through stock '98 manifolds.
I had a set of longtube FLP headers off my buddy's car laying around, so we decided to try 'em and see if it made any difference. Sadly, after having to make a few new pipes and spending nearly all day installing them, we put it back on the dyno and saw absolutely no gain at all. We did notice that the power curve started a little later (about 300-400 rpm's later) and on the street, it seemed to spool noticeably slower.
Since it was a stock engine, I didn't wanna try to make any more power by turning the boost up. I mainly only wanted to see if the long tubes would make anymore power at the same boost. (we were using an E-Boost2, so boost was virtually identical)
I don't have the dyno sheets with me of the long tube pulls (moved 3 times since then), but I do have the dyno sheets still stored on my photobucket of the stock manifold pulls.
Hope this helps:
I can give you my own personal experience. About a year and a half ago, I built a rear mount GT45R turbo system on my '98 Formula A4. Engine was a factory LS6 with Edelbrock Intake, sheetmetal plenum, custom cam (roughly 230/240 @ .050 / .600ish Lift) and .072 thick Cometic headgaskets to lower the compression a bit. I was running 15lbs of boost and making 681rwhp/861rwtq. Through stock '98 manifolds.
I had a set of longtube FLP headers off my buddy's car laying around, so we decided to try 'em and see if it made any difference. Sadly, after having to make a few new pipes and spending nearly all day installing them, we put it back on the dyno and saw absolutely no gain at all. We did notice that the power curve started a little later (about 300-400 rpm's later) and on the street, it seemed to spool noticeably slower.
Since it was a stock engine, I didn't wanna try to make any more power by turning the boost up. I mainly only wanted to see if the long tubes would make anymore power at the same boost. (we were using an E-Boost2, so boost was virtually identical)
I don't have the dyno sheets with me of the long tube pulls (moved 3 times since then), but I do have the dyno sheets still stored on my photobucket of the stock manifold pulls.
Hope this helps:
03-08-2008, 12:07 AM
#4
12 Second Club
iTrader: (6)
Join Date: Jun 2004
Location: Ft. Irwin, California (But Virginia is home)
Posts: 1,501
Likes: 0
Received 7 Likes
on
1 Post
Probably have more Q's than answers, such as trans (was it an auto, and if so, is it a high stall converter locked/unlocked)? You mentioned that the car is running the stock manifolds and a muffler. The turbo should be the "muffler", so this is a point to look at for reduced power. I'd personally recommend eliminating any "restrictor" before the turbo. Wrapping the exhaust will also greatly reduce spool times, though full boost should be achieved by 4000-4500RPM....not 5K+. What turbo is being used? Stock STS 60trim? Might be running out of steam for the engine if so. Also, what is the size of the outlet exhaust pipe from the turbo? A diameter too small will choke the turbo too. Should be a good 3-4" or so for that one.
At 11.5PSI you should be seeing 600+RWHP. You mentioned experience with tuning......so my $0.02 is that if the car is currently in 1-bar SD or MAF to try a 2-bar SD. I switched to the 2-bar last Dec (even though I have only 5PSI) and tuned w/ HP Tuners. Haven't dynoed yet, but the butt-meter noted MASSIVE increases in part-boost and full boost power..... It was very, very noticable. It also reduced spool times from 3.5K to 2.8K for "full boost" because it allowed for "hotter/leaner" exhaust at part boost MAP values (110-125 or so). In short, in 1-bar tuning the car was fuel loading in 1st and 2nd gear to ensure that A/F remained good when the same fuel values were commanded in 4th-6th gear. BTW, I'm running 16* timing too, but set my A/F at 11.01 to 1.
Hope this at least gives you some ideas of where to look. Good luck.
At 11.5PSI you should be seeing 600+RWHP. You mentioned experience with tuning......so my $0.02 is that if the car is currently in 1-bar SD or MAF to try a 2-bar SD. I switched to the 2-bar last Dec (even though I have only 5PSI) and tuned w/ HP Tuners. Haven't dynoed yet, but the butt-meter noted MASSIVE increases in part-boost and full boost power..... It was very, very noticable. It also reduced spool times from 3.5K to 2.8K for "full boost" because it allowed for "hotter/leaner" exhaust at part boost MAP values (110-125 or so). In short, in 1-bar tuning the car was fuel loading in 1st and 2nd gear to ensure that A/F remained good when the same fuel values were commanded in 4th-6th gear. BTW, I'm running 16* timing too, but set my A/F at 11.01 to 1.
Hope this at least gives you some ideas of where to look. Good luck.
03-08-2008, 12:25 AM
#5
TECH Enthusiast
iTrader: (2)
Join Date: May 2006
Location: Washington
Posts: 555
Likes: 0
Received 0 Likes
on
0 Posts
i dont have a dyno graph for you but i agree the cam choice could be a factor. i put down 468rwhp unlocked converter through an A4 with a 9.5-1 motor my cam is a 219 234 589 610 115lsa on 9 psi. others i have seen that put good power down use the TRT cam its a 228 228 cam. we saw an average of 30 hp gain per psi of boost so my calculations are about the same as your seeing. i am not running a muffler before the turbo i also wonder how that is effecting back pressure on the eng?? just some food for thought.
03-08-2008, 06:27 AM
#6
Hi Nick,
The EBoost2 seems to be working okay for me as base boost was 9.2 or so at the manifold and with the EBoost I got to 11.5 with no problem..........so far.
Hey Rob,
It has been a long time for sure. maybe SEMA a few years back. Thanks for the info and I remeber the car.
Schantin,
The car is an M6 and the muffler is a custom stainless piece that did not hinder the power at all at 9.2-9.5 PSI. Just made it more tolerable droan and rasp wise. The exhaust is wrapped from manifolds to turbo. It has a T76 and it is 2Bar tuned. Not sure on the turbo exit but I would guess what STS originally sent with the kit. Again I did not build the combo, just trying to figure it out. If you could please sens me you tune file so I can compare.
smoke20,
I believe this answer most of your questions also and I feel that the cam is only a small part of the issue.
Right now it looks like taking a stock engine and just adding good pistons and rods along with a nice smaller forced induction cam makes more sense then an all out build with a rear mount. The more base engine does not get restricted as much with the exhaust setup and therefore can have the same base horsepower as a built holy crap engine. Maybe the exhaust setup will only flow enough NA to support 325 RWHP???
I would really like to see Zombies dyno, already pretty much know the combo, as well as Schantin and whoever else. Thanks everyone. If you go a search for member geeteego you will see his saga.
Mike Norris
The EBoost2 seems to be working okay for me as base boost was 9.2 or so at the manifold and with the EBoost I got to 11.5 with no problem..........so far.
Hey Rob,
It has been a long time for sure. maybe SEMA a few years back. Thanks for the info and I remeber the car.
Schantin,
The car is an M6 and the muffler is a custom stainless piece that did not hinder the power at all at 9.2-9.5 PSI. Just made it more tolerable droan and rasp wise. The exhaust is wrapped from manifolds to turbo. It has a T76 and it is 2Bar tuned. Not sure on the turbo exit but I would guess what STS originally sent with the kit. Again I did not build the combo, just trying to figure it out. If you could please sens me you tune file so I can compare.
smoke20,
I believe this answer most of your questions also and I feel that the cam is only a small part of the issue.
Right now it looks like taking a stock engine and just adding good pistons and rods along with a nice smaller forced induction cam makes more sense then an all out build with a rear mount. The more base engine does not get restricted as much with the exhaust setup and therefore can have the same base horsepower as a built holy crap engine. Maybe the exhaust setup will only flow enough NA to support 325 RWHP???
I would really like to see Zombies dyno, already pretty much know the combo, as well as Schantin and whoever else. Thanks everyone. If you go a search for member geeteego you will see his saga.
Mike Norris
03-08-2008, 09:08 AM
#7
11 Second Club
iTrader: (1)
Join Date: Aug 2007
Location: Orlando, FL
Posts: 503
Likes: 0
Received 0 Likes
on
0 Posts
Long and the short of it: This is a car that should be over 750hp on this third retune, as I was hoping getting back in and sorting out various boost issues and getting a controller on to up the ante a bit.
Car built by Tom Tiberio...GTO guys know him very well. It's an LQ9 stock bore/stroke, Callies compstar rods and diamond -13.7 pistons. Stock crank. Figure SCR to be ~9.0:1.
Heads are 243's ported by Formato. Valvetrain appeared intact when Mike looked at it...Patriot Golds, hardened pushrods, etc. Intake is a Victor Jr with custom elbow and 90mm ported TB.
It's a M6 car with a SPEC 2+ clutch that was holding just fine. Stock gearing.
To fill in the gaps, Mike, correct me if I'm out of school:
Car is falling off about 50 rwhp at 5900rpm. Almost like it's losing a cylinder. Mike checked the plugs and regapped with the same result. No pinging, knock, or detonation, just falling flat and losing hp where it should still be climbing or at worst, leveling off a bit.
AFR is 12.0:1 pretty much all the way through. No fueling problems there it would appear.
FPR drops to 50psi at full boost from 60 at idle, but again, AFR is good. We'll be into the fuel system soon.
Turbo is a 76GTS T4 flange that should be working fine...connected to the OE STS piping (hot and cold).
Things I suspect:
1. Muffler
2. Pushrod(s)
3. Turbo (again)
4. Cam
5. OE STS piping (not enough diameter to support this)
Help! I want this car back on it's feet where it should be.
Car built by Tom Tiberio...GTO guys know him very well. It's an LQ9 stock bore/stroke, Callies compstar rods and diamond -13.7 pistons. Stock crank. Figure SCR to be ~9.0:1.
Heads are 243's ported by Formato. Valvetrain appeared intact when Mike looked at it...Patriot Golds, hardened pushrods, etc. Intake is a Victor Jr with custom elbow and 90mm ported TB.
It's a M6 car with a SPEC 2+ clutch that was holding just fine. Stock gearing.
To fill in the gaps, Mike, correct me if I'm out of school:
Car is falling off about 50 rwhp at 5900rpm. Almost like it's losing a cylinder. Mike checked the plugs and regapped with the same result. No pinging, knock, or detonation, just falling flat and losing hp where it should still be climbing or at worst, leveling off a bit.
AFR is 12.0:1 pretty much all the way through. No fueling problems there it would appear.
FPR drops to 50psi at full boost from 60 at idle, but again, AFR is good. We'll be into the fuel system soon.
Turbo is a 76GTS T4 flange that should be working fine...connected to the OE STS piping (hot and cold).
Things I suspect:
1. Muffler
2. Pushrod(s)
3. Turbo (again)
4. Cam
5. OE STS piping (not enough diameter to support this)
Help! I want this car back on it's feet where it should be.
Last edited by geeteego; 03-08-2008 at 09:19 AM.
Trending Topics
03-08-2008, 10:06 AM
#9
11 Second Club
iTrader: (1)
Join Date: Aug 2007
Location: Orlando, FL
Posts: 503
Likes: 0
Received 0 Likes
on
0 Posts
Like Mike said, a NA pull will give us a LOT of information, I agree with that.
Fuel system is a 255lph Walbro GS340 with Edelbrock rails, 60# injectors, and a KB Boost-a-pump. Injectors were around 80%DC.
We didn't do a compression test...yet. It might also explain the lack of power...and it could be some tiny bits that we're just not seeing.
03-08-2008, 06:45 PM
#11
Staging Lane
Join Date: Jan 2008
Location: Louisville, Ky Area
Posts: 64
Likes: 0
Received 0 Likes
on
0 Posts
Yea Mike, I think it was SEMA. I miss getting to go to that.
Anywho, a couple things:
1.) I don't think you're getting into the efficiency range of that turbo at only 11lbs of boost. Provided that the "falling off" of power at 5900 isn't some other issue, I think upping the boost to 15+ would make a huge gain. I found that the larger the turbo, the less linear the hp gain is per pound of boost (at least at low boost levels).
2.) I don't believe the muffler is an issue.
3.) Possible weak valvesprings causing the 5900 drop in power. If so, it should get more drastic by upping the boost a pound or two (obviously).
4.) It's also too lean, IMHO. Needs to be in the low 11's on the dyno from about 4500 up. As I also believe this is causing a loss in power. (double-pumper and a 1:1 regulator would cure all of the fueling issues up to about 800rwhp)
5.) Cam - Again, IMHO, I don't think that's causing you any problem at all.
6.) Lastly, I do think the small piping is somewhat of an issue. I experimented with a 2 1/2" and 3" discharge pipe. Never dyno tested it, but I can say with certainty that the 3" pipe "felt" noticeably stronger on the street when were only making about 600rwhp. I also noticed that the IAT's were consistently about 10 degrees lower with the 3" pipe vs 2 1/2".
That's all I can think of for now....
Anywho, a couple things:
1.) I don't think you're getting into the efficiency range of that turbo at only 11lbs of boost. Provided that the "falling off" of power at 5900 isn't some other issue, I think upping the boost to 15+ would make a huge gain. I found that the larger the turbo, the less linear the hp gain is per pound of boost (at least at low boost levels).
2.) I don't believe the muffler is an issue.
3.) Possible weak valvesprings causing the 5900 drop in power. If so, it should get more drastic by upping the boost a pound or two (obviously).
4.) It's also too lean, IMHO. Needs to be in the low 11's on the dyno from about 4500 up. As I also believe this is causing a loss in power. (double-pumper and a 1:1 regulator would cure all of the fueling issues up to about 800rwhp)
5.) Cam - Again, IMHO, I don't think that's causing you any problem at all.
6.) Lastly, I do think the small piping is somewhat of an issue. I experimented with a 2 1/2" and 3" discharge pipe. Never dyno tested it, but I can say with certainty that the 3" pipe "felt" noticeably stronger on the street when were only making about 600rwhp. I also noticed that the IAT's were consistently about 10 degrees lower with the 3" pipe vs 2 1/2".
That's all I can think of for now....
03-08-2008, 08:19 PM
#12
TECH Enthusiast
iTrader: (2)
Join Date: May 2006
Location: Washington
Posts: 555
Likes: 0
Received 0 Likes
on
0 Posts
one other thing i forgot to bring up Zombie runs in Vegas his DA is like 2500 so if you factor that into the equation he is a high 9 car closer to sea level.
that could be why the calculations dont add up to his 1/4 mile times.
also Zombie runs a very tall gear to help spool the turbo , i think he runs a 2.90 so his car takes some time to get up im sure , compared to a N/A car that is quicker but has less trap speed.
that could be why the calculations dont add up to his 1/4 mile times.
also Zombie runs a very tall gear to help spool the turbo , i think he runs a 2.90 so his car takes some time to get up im sure , compared to a N/A car that is quicker but has less trap speed.
Last edited by smoke20; 03-08-2008 at 08:25 PM. Reason: info
03-08-2008, 09:34 PM
#13
Thanks again everyone.
The power drop is not not related to boost, timing or fuel. It is a quick 50 HP drop, not a smooth drop. You can feel & hear it on the dyno and it "feels" like valve float to me, but it is after peak boost and and peak torque and maybe shorting the peak HP about 25 or so. It is a problem for sure and most likely boost related as I raise it up. I do agree it is on the leaner side then I like, but had no KR and not a big difference at 11.0 to 1 A/F. I was simply trying to see what the car liked and disliked. Once i was done I add 4% fuel for Ronnie to drive her around on.
Though the fuel syatem may only be good for 650-ish RWHP and the pressure dips, I can still control the A/F without radical changes. I think I can get to 650 like ronnie wants with the current fuel system with the only change being a boost referenced regulator and proper return to get rid of the factory in tank regulator.
Once I have a naturally aspirated run I will have a better grasp on where to go next. If it does end up in the 310-320 RWHP area as I am thinking, then next would be to get rid of the STS inlet tubing and just have a filter up in the engine bay and see what that does. After that a set of headers to simulate a more proper N/A setup. If this produces 425-450 RWHP then I would feel the engine is fine and just restricted by the STS package. If no headers are available to test, then at least a couple 2.5" pipes off the stock manifolds. We will see. If need be a compression test, checking timing chain alignment & degreeing, as well as checking the springs for proper install heights and pressures after all is said and done.
Again thanks for all the info and if at all possible please post up some dyno sheets as well as longrange4u setup it would help me very much. I look forward to learning more on this and helping out geeteego's project.
Mike Norris
The power drop is not not related to boost, timing or fuel. It is a quick 50 HP drop, not a smooth drop. You can feel & hear it on the dyno and it "feels" like valve float to me, but it is after peak boost and and peak torque and maybe shorting the peak HP about 25 or so. It is a problem for sure and most likely boost related as I raise it up. I do agree it is on the leaner side then I like, but had no KR and not a big difference at 11.0 to 1 A/F. I was simply trying to see what the car liked and disliked. Once i was done I add 4% fuel for Ronnie to drive her around on.
Though the fuel syatem may only be good for 650-ish RWHP and the pressure dips, I can still control the A/F without radical changes. I think I can get to 650 like ronnie wants with the current fuel system with the only change being a boost referenced regulator and proper return to get rid of the factory in tank regulator.
Once I have a naturally aspirated run I will have a better grasp on where to go next. If it does end up in the 310-320 RWHP area as I am thinking, then next would be to get rid of the STS inlet tubing and just have a filter up in the engine bay and see what that does. After that a set of headers to simulate a more proper N/A setup. If this produces 425-450 RWHP then I would feel the engine is fine and just restricted by the STS package. If no headers are available to test, then at least a couple 2.5" pipes off the stock manifolds. We will see. If need be a compression test, checking timing chain alignment & degreeing, as well as checking the springs for proper install heights and pressures after all is said and done.
Again thanks for all the info and if at all possible please post up some dyno sheets as well as longrange4u setup it would help me very much. I look forward to learning more on this and helping out geeteego's project.
Mike Norris
03-09-2008, 11:28 AM
#14
LS1Tech Co-Founder
iTrader: (34)
If we look at the dyno numbers, the car should dyno NA around 375rwhp no problem, maybe 400rwhp yes? At 1 bar (15 psi) numbers could easily look like 750rwhp through an M6 though I would be happy with 675rwhp and assume there might be little more in it.
So I'm thinking you should be shooting for 600rwhp, 575rwhp would be okay for starters, unless the rear mounts are lot less efficient.
I think if you go through Rob's list you will find more power. What pushrods would be typical for that combo, 7.400? I have no idea BTW. Personally on my Formula valvesprings have been swapped a few times over the years like for example when the 832's were not enough.
So I'm thinking you should be shooting for 600rwhp, 575rwhp would be okay for starters, unless the rear mounts are lot less efficient.
I think if you go through Rob's list you will find more power. What pushrods would be typical for that combo, 7.400? I have no idea BTW. Personally on my Formula valvesprings have been swapped a few times over the years like for example when the 832's were not enough.
03-09-2008, 11:51 AM
#15
11 Second Club
iTrader: (1)
Join Date: Aug 2007
Location: Orlando, FL
Posts: 503
Likes: 0
Received 0 Likes
on
0 Posts
Thanks for the input Rob and John.
Rear mounts are pretty inefficient in my experience. Lots of heat loss to the compressor and a long way to travel to the manifold. I've seen about a 2psi dichotomy from what the turbo is making vs what is registering at the intake.
I'll agree that conservatively speaking, the car should be around ~650rwhp with the fuel system being the limiting factor for really turning up the wick. Before, the car made 626rwhp on the stock-internal LS1 with the same cam, but an LS6 intake instead of the elbow/VJ with box-stock 241's wearing the valvetrain upgrades. It blew up. This one should be much safer, and exhibit quite a bit more power with both more cubes and less SCR to allow for extra inhaled air.
The valvetrain is as new as the motor, John, so it shouldn't (operative word) be suspect with ~3500 miles on it. As far as pushrod length, yes, 7.400 is correct.
I know Mike is as befuddled as me on this.
Rear mounts are pretty inefficient in my experience. Lots of heat loss to the compressor and a long way to travel to the manifold. I've seen about a 2psi dichotomy from what the turbo is making vs what is registering at the intake.
I'll agree that conservatively speaking, the car should be around ~650rwhp with the fuel system being the limiting factor for really turning up the wick. Before, the car made 626rwhp on the stock-internal LS1 with the same cam, but an LS6 intake instead of the elbow/VJ with box-stock 241's wearing the valvetrain upgrades. It blew up. This one should be much safer, and exhibit quite a bit more power with both more cubes and less SCR to allow for extra inhaled air.
The valvetrain is as new as the motor, John, so it shouldn't (operative word) be suspect with ~3500 miles on it. As far as pushrod length, yes, 7.400 is correct.
I know Mike is as befuddled as me on this.
03-09-2008, 12:10 PM
#16
Coal Mining Director
iTrader: (17)
Join Date: Nov 2001
Location: Virginia
Posts: 4,442
Likes: 0
Received 0 Likes
on
0 Posts
"This thing already barely spools as it is and hits full boost at 5000 RPM"
There's a big data point for your problems.
I would start looking for that cause first. You need hot exhaust to spool a turbo.
A muffler before the turbo on a rear mount could cause big problems....could be a major heat/velocity loss.
If it were my car the first things I would do (KISS):
1. Remove the muffler before the turbo.
2. Big open pipe after the turbo.
3. Start adding timing down low/high and see what the combo likes to make
safe power.
Get the power fixed then look at quieting it down with minimal loss..
Can you post the dyno sheet?
There's a big data point for your problems.
I would start looking for that cause first. You need hot exhaust to spool a turbo.
A muffler before the turbo on a rear mount could cause big problems....could be a major heat/velocity loss.
If it were my car the first things I would do (KISS):
1. Remove the muffler before the turbo.
2. Big open pipe after the turbo.
3. Start adding timing down low/high and see what the combo likes to make
safe power.
Get the power fixed then look at quieting it down with minimal loss..
Can you post the dyno sheet?
03-09-2008, 12:42 PM
#17
PSJ, I would think the engine with an optimized headers & exhaust and proper cold air intake would make 425-450 RWHP NA. I plan on dropping the turbo and using the existing stock manifolds, 2-2.5" exhaust, muffler and intake drawn from the rear as it is with the STS package to see what it can do as it is setup.
I think it is a very inefficient system in that spool time can be slow and there is most likely quite a difference in pressure between the comprssor housing and the TB, but not matter what we have 11.5 PSI at the manifold.
I am still stuck on the theory that 1 Bar (14.8 to 15 PSI) at the manifold doubles the horsepower. Therefore 11.5 PSI at the manifold should add 75-80 percent. Figuring an M6 like we have, 400 RWHP NA would be 700-720 RWHP at 11.5 PSI. At 315 RWHP NA you would see 550-560 RWHP at 11.5 PSI.
Now as far as the forever to spool, I agree that heat, or lack there of, and rear location have a lot to do with it. I will try a few other items as discussed here as it is good testing.
onfire, I have leaned her out down low as well as normal NA timing up to about 3500-4000 where boost finally starts to come in decent. No help in that area. The cars power output did not change at 9 PSI between an open pipe and adding the muffler. I do not see it making much difference at 11.5 PSI, but we will see. It is a custom piece with minimal baffling. More a resonator then muffler. I do need to verify the pipe out of the turbo as to be honest I have no idea what size it is. Definitely a possiblility.
We will start with the basics and get more intrusive engine wise (valvetrain preload, spring setup, cam timing) dependant on the results of the tests. The 7.400's are 90 percent of what these engines use, but I have used several 7.350" and 7.325" long units as well to get the preload I want. The base NA dyno will tell me a lot.
Thanks again everyone.
Mike Norris
I think it is a very inefficient system in that spool time can be slow and there is most likely quite a difference in pressure between the comprssor housing and the TB, but not matter what we have 11.5 PSI at the manifold.
I am still stuck on the theory that 1 Bar (14.8 to 15 PSI) at the manifold doubles the horsepower. Therefore 11.5 PSI at the manifold should add 75-80 percent. Figuring an M6 like we have, 400 RWHP NA would be 700-720 RWHP at 11.5 PSI. At 315 RWHP NA you would see 550-560 RWHP at 11.5 PSI.
Now as far as the forever to spool, I agree that heat, or lack there of, and rear location have a lot to do with it. I will try a few other items as discussed here as it is good testing.
onfire, I have leaned her out down low as well as normal NA timing up to about 3500-4000 where boost finally starts to come in decent. No help in that area. The cars power output did not change at 9 PSI between an open pipe and adding the muffler. I do not see it making much difference at 11.5 PSI, but we will see. It is a custom piece with minimal baffling. More a resonator then muffler. I do need to verify the pipe out of the turbo as to be honest I have no idea what size it is. Definitely a possiblility.
We will start with the basics and get more intrusive engine wise (valvetrain preload, spring setup, cam timing) dependant on the results of the tests. The 7.400's are 90 percent of what these engines use, but I have used several 7.350" and 7.325" long units as well to get the preload I want. The base NA dyno will tell me a lot.
Thanks again everyone.
Mike Norris
03-09-2008, 01:38 PM
#19
Coal Mining Director
iTrader: (17)
Join Date: Nov 2001
Location: Virginia
Posts: 4,442
Likes: 0
Received 0 Likes
on
0 Posts
If it's too small in diameter, length doesn't matter. What's the exducer size of the turbine? What's the diameter of the pipe? I'd also worry about the muffler being more of a heat loss since it's a big chamber as compared to a pipe. Good thing is it's all easy stuff to test.
03-09-2008, 01:40 PM
#20
Staging Lane
Join Date: Jan 2008
Location: Louisville, Ky Area
Posts: 64
Likes: 0
Received 0 Likes
on
0 Posts
To be honest, I missed the part about the super slow spool up. What size exhaust housing is on the turbo??
Again, I ran a T76GTS for quite a while. I can tell you for sure that it doesn't like to make power at low boost. So if it were me, here's what I'd try (in order):
1.) Double-check turbo for end play (because that's simple to do in that location).
2.) Put a good set of valvesprings on it again. With a cam, I always use 7.35 pushrods.
3.) Re-dyno at the same boost and see if the 5900 dip in power is still there.
4.) If so, I would run larger discharge pipe (I realize that's not so simple).
4.) If not, turn the boost up gradually and the power should start to jump way up. That 76GTS likes 20-25lbs for good efficiency. Even though I know you won't get anywhere near that. But you will need to be running at least 15-18lbs, IMHO.
Again, I ran a T76GTS for quite a while. I can tell you for sure that it doesn't like to make power at low boost. So if it were me, here's what I'd try (in order):
1.) Double-check turbo for end play (because that's simple to do in that location).
2.) Put a good set of valvesprings on it again. With a cam, I always use 7.35 pushrods.
3.) Re-dyno at the same boost and see if the 5900 dip in power is still there.
4.) If so, I would run larger discharge pipe (I realize that's not so simple).
4.) If not, turn the boost up gradually and the power should start to jump way up. That 76GTS likes 20-25lbs for good efficiency. Even though I know you won't get anywhere near that. But you will need to be running at least 15-18lbs, IMHO.