ZO6 LS7 does not run like I think it should.
11-17-2014, 05:31 PM
#1
Launching!
Thread Starter
ZO6 LS7 does not run like I think it should. have a 2008 ZO6 LS7. In my 32ford pro street truck. I do not think it has ever run, as fast as it should. HELP what is wrong. It has 1-7/8s stainless headers. Plus two different cams. It runs 6.40s in the 1/8 @ 105mph. And it runs 10.00s @ 127 in the 1/4. I have a turbo 400, trans. It has had two different gears & stalls. The 1st combo was 4800 stall & 4.30 gears. Second combo 2800 to 3000 stall & 3.50 gears. The truck is 2660 with me in it. I have had two different cams also. Both were custom grinds for the truck. Could it be the stock intake, air intake system, with just a high flow filter. Or is it in the drive by wire stock set up. It has been tuned twice. One time for each cam, and gear, stall combo. It is like anything we do to it. Makes no difference. Do I need to change the stock air box, and stock sensor? HELP!!!!!!!!!!!!!!!!
Both converters were.PTC 10" stalls. foot brake at 1700 rpm. No cats, 2 chamber flowmasters with turn downs just in front of rear end. I just run one set of O2s. Total exhaust length 2-1/2 feet.. Had one chambers on it. No difference. We checked compression & leak down. Everything OK there. Check my OP and you will see. I have had two different stalls & gear combos.
1st cam 2nd cam
intake & exh lobe sep- 114.2 112
intake center line 111.2 108
intake duration 242.6 234.4
intake valve lift 648 648
intake lobe lift 360 360
exh centerline 117.2 116
exh duration 248.6 242
exh valve lift 649 630
exh lobe lift 360 350
Both converters were.PTC 10" stalls. foot brake at 1700 rpm. No cats, 2 chamber flowmasters with turn downs just in front of rear end. I just run one set of O2s. Total exhaust length 2-1/2 feet.. Had one chambers on it. No difference. We checked compression & leak down. Everything OK there. Check my OP and you will see. I have had two different stalls & gear combos.
1st cam 2nd cam
intake & exh lobe sep- 114.2 112
intake center line 111.2 108
intake duration 242.6 234.4
intake valve lift 648 648
intake lobe lift 360 360
exh centerline 117.2 116
exh duration 248.6 242
exh valve lift 649 630
exh lobe lift 360 350
11-17-2014, 06:52 PM
#2
What was RWHP each time when tuned? RWHP calculators aren't exact, but give a general idea of RWHP, as well. Foot brake @ 1700 is an issue in terms of a decent 60'. Have you confirmed that the TB blade is 100% open @ WOT? Other than that, make a run with air filter removed & see what happens. Should add reduce time by around 0.10.
My guess is that the TB is not 100% open @ WOT.
My guess is that the TB is not 100% open @ WOT.
11-17-2014, 07:20 PM
#3
TECH Senior Member
iTrader: (7)
What harness and ECU? With that weight, even a stock LS7 should trap over 130, more like 135...
If I was a betting man, I would say the problem is in your transmission.
Andrew
If I was a betting man, I would say the problem is in your transmission.
Andrew
11-17-2014, 08:43 PM
#4
Launching!
Thread Starter
Stock harness reworked by speartech. stock ECU worked by speartech. Then tuned by intune motorsports.
11-17-2014, 11:44 PM
#6
https://www.texas-speed.com/p-676-fa...-manifold.aspx
Also, how did your times change between the gear changes? At 127mph you're somewhere near 5500 rpm in the traps with the 3.50s which is less than ideal....what's your 60 foot?
11-18-2014, 09:10 AM
#7
Launching!
Thread Starter
Yes. But, the stock intake isn't terrible. You're still trapping 127 which is hauling just fine for a non-aerodynamic car. You're picking up 22mph between the 1/8th and the 1/4 which isn't bad for an auto. But, a FAST will pick up a bunch more for a bunch more $$$. And what do you mean by stock air intake? Running the same one from a Corvette? Try a custom one.
https://www.texas-speed.com/p-676-fa...-manifold.aspx
Also, how did your times change between the gear changes? At 127mph you're somewhere near 5500 rpm in the traps with the 3.50s which is less than ideal....what's your 60 foot?
https://www.texas-speed.com/p-676-fa...-manifold.aspx
Also, how did your times change between the gear changes? At 127mph you're somewhere near 5500 rpm in the traps with the 3.50s which is less than ideal....what's your 60 foot?
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11-18-2014, 10:31 AM
#8
Launching!
Thread Starter
11-18-2014, 01:31 PM
#9
Yeah, that setup is killing you a bit I bet. With the radiator so close I bet you'd be a good candidate for a carb-style intake with a TB or something like the Holley High-ram to try to get the TB up higher. https://ls1tech.com/forums/generatio...s7-intake.html
That's a really neat idea though, but probably not best for airflow.
11-19-2014, 01:21 PM
#10
Launching!
Thread Starter
What does everyone think about the LS7 single plane intakes, with a throttle body? I have thought about trying that, and keeping the fuel injection.
11-19-2014, 04:49 PM
#12
Launching!
Thread Starter
http://i638.photobucket.com/albums/u...ps4e2033d5.jpg
What do you need to do to convert, to a set up like this? And would it work better that what I have? CAN I STILL USE MY STOCK COMPUTER, injectors, fuel rails & DBW? And how do you tune it?
What do you need to do to convert, to a set up like this? And would it work better that what I have? CAN I STILL USE MY STOCK COMPUTER, injectors, fuel rails & DBW? And how do you tune it?
11-19-2014, 07:54 PM
#13
That's a single plane intake, fuel rails, injectors, a 4150 or 4500 throttle-body with TPS, IAC, AIT and MAP sensors. No MAF. Your stock E38 computer will not work without DBW I believe and the tune will have to be done in SD only unless you run an elbow and a MAF. Also, those throttle-bodies are normally cable-driven, but there are DBW conversion parts for them that work fine.
You can also do something like this: http://www.corvetteforum.com/forums/...-690-rwhp.html
and run your DBW TB vertical, with a 4" tube to your MAF to your airbox/filter. Then you can run a MAF still. Seems to make power for that guy! Here's an adapter...it's not cheap...http://www.schwartzperformance.com/b...-body-adapter/
And another: http://www.mastmotorsports.com/view.php?id=487&c=32&s=7
So, best bet might be to run your stock TB with an adapter on a carb-manifold with the MAF between the TB and your filter-box that's directly above it. It would be an interesting experiment at least.
Last edited by 1970camaroRS; 11-19-2014 at 08:00 PM.
11-20-2014, 10:37 AM
#14
TECH Senior Member
iTrader: (7)
Why not run a Holley Hi-Ram with the EFI top? You have enough room under the hood. This will raise the intake and you can retain the MAF by routing having a 90 degree elbow off the TB and having a 4" tube with the MAF intact.
You can reuse your stock injectors.
Andrew
You can reuse your stock injectors.
Andrew
11-20-2014, 01:09 PM
#15
Launching!
Thread Starter
I thought the converter & gear might have been a problem. They were from my old set up. that gear ratio was a 4.30 & an the stall was a 4800. I changed that out to a 3.50 rear gear 1st.ETs stayed almost exactly the same as with the 4.30 gear. Then I went to, a 2800 to 3000 stall. Very little change in performance at all. I lost a little 60ft. It went from 1.38/1.44 foot braking to 1.46 to 1.50. I am like you. I think with the truck weight at 2660 with me in it, the truck should be flying.
Something is just off so where. Oh by the was I run a Weldon FI fuel pump go for 1000HP. My old A600 I thought might have been border line. So I went to the next size up Weldon FI pump. However I do run a bypass regulator, back to the fuel cell. Instead of dead heading at the fuel rails. I often wondered if that could be a problem. But at the track. The A/F ratios look good during a run.
Something is just off so where. Oh by the was I run a Weldon FI fuel pump go for 1000HP. My old A600 I thought might have been border line. So I went to the next size up Weldon FI pump. However I do run a bypass regulator, back to the fuel cell. Instead of dead heading at the fuel rails. I often wondered if that could be a problem. But at the track. The A/F ratios look good during a run.
11-20-2014, 05:33 PM
#16
Why not run a Holley Hi-Ram with the EFI top? You have enough room under the hood. This will raise the intake and you can retain the MAF by routing having a 90 degree elbow off the TB and having a 4" tube with the MAF intact.
You can reuse your stock injectors.
Andrew
You can reuse your stock injectors.
Andrew
11-20-2014, 05:42 PM
#17
I thought the converter & gear might have been a problem. They were from my old set up. that gear ratio was a 4.30 & an the stall was a 4800. I changed that out to a 3.50 rear gear 1st.ETs stayed almost exactly the same as with the 4.30 gear. Then I went to, a 2800 to 3000 stall. Very little change in performance at all. I lost a little 60ft. It went from 1.38/1.44 foot braking to 1.46 to 1.50. I am like you. I think with the truck weight at 2660 with me in it, the truck should be flying.
Something is just off so where. Oh by the was I run a Weldon FI fuel pump go for 1000HP. My old A600 I thought might have been border line. So I went to the next size up Weldon FI pump. However I do run a bypass regulator, back to the fuel cell. Instead of dead heading at the fuel rails. I often wondered if that could be a problem. But at the track. The A/F ratios look good during a run.
Something is just off so where. Oh by the was I run a Weldon FI fuel pump go for 1000HP. My old A600 I thought might have been border line. So I went to the next size up Weldon FI pump. However I do run a bypass regulator, back to the fuel cell. Instead of dead heading at the fuel rails. I often wondered if that could be a problem. But at the track. The A/F ratios look good during a run.
As long as your injectors are setup to operate with constant pressure and your AFR is good, then you're good with the return system.
11-20-2014, 07:24 PM
#18
Launching!
Thread Starter
I did try the 4800 with the 3.50 gears. No real difference. This is a real puzzle to me. I have been racing since, 1966. This is my 1st LS style motor. And it just does not seem, to respond to anything I do to it. I am hoping you guys can help me figure this out.
Last edited by bada; 12-09-2014 at 05:01 PM. Reason: .
11-20-2014, 07:52 PM
#20
Are you using anything to log your runs? AFR? Fuel pressure?
Honestly, the only thing odd is no change in ET, MPH or 60' with the gears and stall. Your ET and MPH seems to match up pretty well with your power level, weight and aero. The restriction from the elephant-trunk style intake tube probably isn't a whole lot in all reality...but you would for-sure gain with a better intake manifold and tube. But, I'd hate to see you spend a ton of cash only to find out it was something like 100% injector duty cycle or a drop of fuel pressure at the top-end.
Honestly, the only thing odd is no change in ET, MPH or 60' with the gears and stall. Your ET and MPH seems to match up pretty well with your power level, weight and aero. The restriction from the elephant-trunk style intake tube probably isn't a whole lot in all reality...but you would for-sure gain with a better intake manifold and tube. But, I'd hate to see you spend a ton of cash only to find out it was something like 100% injector duty cycle or a drop of fuel pressure at the top-end.