402 with the bottle... questions/help
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402 with the bottle... questions/help **UPDATED** I've got a 402 LS1 in my '91 GTA... basic setup as follows.
402ci
330cfm heads
250*-ish/.620"-ish cam
FAST 90/90 setup
85mm MAF
4" CAI setup
1-3/4" SW LT's with stepped down 2.5" collectors
2.5" sweet thunder true duals with x-pipe and dumps
6-speed with Textralia
HD chromemoly DS
9" with spool and 4.11's
The car puts down 484RWHP and 440RWTQ NA.
On the bottle it is only putting down 603RWHP and 598 RWTQ.
It is a NX kit with a shark nozzle mounted about 5" in front of the TB and 150 jets in it.
Situation:
When we made the initial pulls with 19* of timing it did 445RWHP NA and 595RWHP n2o, basically picking up the full 150 shot at the wheels. By the end of the dyno tuning session we had 24* of timing in it and were putting down 474RWHP NA and 603RWHP n2o. (only picking up 129RWHP)
Question:
I think the car should still be picking up the full 150RWHP at 24* like it did at 19*. Why wouldn't it be? AFR was great across the board on all pulls and the only thing changed from pull to pull was the timing. Jets and computer fueling was left alone.
*Probably a dumb question, but how bad are my 2.5" collectors and 2.5" true duals killing my power? I think the 2.5" is probably maxed out NA and just can't keep up on the bottle. Do you guys think I will pick up much power going to 3" collectors and 3" TD's?
Thoughts? Comments?
Thanks!
-Jeremy
402ci
330cfm heads
250*-ish/.620"-ish cam
FAST 90/90 setup
85mm MAF
4" CAI setup
1-3/4" SW LT's with stepped down 2.5" collectors
2.5" sweet thunder true duals with x-pipe and dumps
6-speed with Textralia
HD chromemoly DS
9" with spool and 4.11's
The car puts down 484RWHP and 440RWTQ NA.
On the bottle it is only putting down 603RWHP and 598 RWTQ.
It is a NX kit with a shark nozzle mounted about 5" in front of the TB and 150 jets in it.
Situation:
When we made the initial pulls with 19* of timing it did 445RWHP NA and 595RWHP n2o, basically picking up the full 150 shot at the wheels. By the end of the dyno tuning session we had 24* of timing in it and were putting down 474RWHP NA and 603RWHP n2o. (only picking up 129RWHP)
Question:
I think the car should still be picking up the full 150RWHP at 24* like it did at 19*. Why wouldn't it be? AFR was great across the board on all pulls and the only thing changed from pull to pull was the timing. Jets and computer fueling was left alone.
*Probably a dumb question, but how bad are my 2.5" collectors and 2.5" true duals killing my power? I think the 2.5" is probably maxed out NA and just can't keep up on the bottle. Do you guys think I will pick up much power going to 3" collectors and 3" TD's?
Thoughts? Comments?
Thanks!
-Jeremy
Last edited by GTA91; Oct 30, 2007 at 10:18 PM.
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Because N/A it wants more timing and on the bottle it doesnt.? Whats the problem? Nitrous doesn't need more timing because it speeds up the combustion process. The car should be ran with optimal N/A timing. When nitrous is applied, you should pull timing electronically with a retard box.
130rwhp gain isn't bad for a .062" jet. I'd at least try 3" collectors with extensions to see if power picks up before doing a new 3" system. I'm assuming you can just slip the 2.5's off and add 3's...goodluck, all I know is that's a bad *** thirdgen!
130rwhp gain isn't bad for a .062" jet. I'd at least try 3" collectors with extensions to see if power picks up before doing a new 3" system. I'm assuming you can just slip the 2.5's off and add 3's...goodluck, all I know is that's a bad *** thirdgen!
Last edited by AutoRoc; Sep 29, 2007 at 02:25 PM.
Thread Starter
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From: St.Louis, Missouri
Yeah I want to do a tricker box or something to pull timing so I can normally run my optimal NA tune.
I ordered a few upgrades for my nitrous kit, gonna try a few things out. Also temporarily changed my exhaust to a 2.5" ORY and a single 4" bullet system. This fall/winter I'm going to 3" collectors and either 3" TD's or a 3" ORY into a single 4" over the axle setup.
Thanks for the compliments, the car has come a long way from my senior year of high school in '99 and it being stock. I've done everything myself except this shortblock, the LS1 wiring, and the tuning. Gotta thank my good friends Glen, Josh, and Tim for that!
I ordered a few upgrades for my nitrous kit, gonna try a few things out. Also temporarily changed my exhaust to a 2.5" ORY and a single 4" bullet system. This fall/winter I'm going to 3" collectors and either 3" TD's or a 3" ORY into a single 4" over the axle setup.
Thanks for the compliments, the car has come a long way from my senior year of high school in '99 and it being stock. I've done everything myself except this shortblock, the LS1 wiring, and the tuning. Gotta thank my good friends Glen, Josh, and Tim for that!
Trending Topics
What's the AFR look like NA and on juice?
What are you running for a fuel system? Are you pulling fuel from the rail?
My 402 made 492 rwhp NA w/ 25* of timing and 680 something on a 150 shot w/ 21* when I was stick. Picked up over 200 ft lbs of torque. I was pulling fuel off the rail and ended up starving #7 cylinder and hurt a piston pretty bad.
What are you running for a fuel system? Are you pulling fuel from the rail?
My 402 made 492 rwhp NA w/ 25* of timing and 680 something on a 150 shot w/ 21* when I was stick. Picked up over 200 ft lbs of torque. I was pulling fuel off the rail and ended up starving #7 cylinder and hurt a piston pretty bad.
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Thread Starter
9 Second Club
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From: St.Louis, Missouri
I think AFR was 12.0 on the bottle, not 100% sure though.
MAF is a GM one.
I'm also pulling fuel off of the rail.
492 NA and 680 n2o on a 150 shot? WTF man... that's a little more than a 150 shot... actually alot more.
MAF is a GM one.
I'm also pulling fuel off of the rail.
492 NA and 680 n2o on a 150 shot? WTF man... that's a little more than a 150 shot... actually alot more.
Thread Starter
9 Second Club
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From: St.Louis, Missouri
Updates... got the car back on the dyno tonight.
Changes from the old setup:
-swapped the 2.5" TD's for a 2.5" ORY into single 4" exhaust
-swapped the -3 nitrous line to a SHO line (-4 line with a -3 end for my shark nozzle)
-switched from MAF to SD... car now has full 4" from the air filter to the 90mm TB
-completely new tune for SD
results:
520RWHP & 475RWTQ on the motor
646RWHP & 637RWTQ on a 150 shot
The car is still only picking up about 125RWHP on a 150 shot. I upped the jets to a 175 shot and it picked up a bunch... went to 684RWHP and 673RWTQ.
I'm pretty happy with it for now. The car went 10.34 @ 134.64 a few weeks ago... hoping for 9's now.
Hoping to add a plate and stand alone fuel system this winter along with drag shocks and a cage.
Changes from the old setup:
-swapped the 2.5" TD's for a 2.5" ORY into single 4" exhaust
-swapped the -3 nitrous line to a SHO line (-4 line with a -3 end for my shark nozzle)
-switched from MAF to SD... car now has full 4" from the air filter to the 90mm TB
-completely new tune for SD
results:
520RWHP & 475RWTQ on the motor
646RWHP & 637RWTQ on a 150 shot
The car is still only picking up about 125RWHP on a 150 shot. I upped the jets to a 175 shot and it picked up a bunch... went to 684RWHP and 673RWTQ.
I'm pretty happy with it for now. The car went 10.34 @ 134.64 a few weeks ago... hoping for 9's now.
Hoping to add a plate and stand alone fuel system this winter along with drag shocks and a cage.
I bet the big gains you saw were from putting a different exhaust on it. Get those headers off and put some 1 7/8 primary units on with a 3 in. min collector and you will probably see a bunch more. I'm gonna guess that you are at the limit of the headers, removing/changing the exhaust helped out a bunch, but going to a bigger primary will get you a good bit more, especially on the bottle
