CamOnlyJabroni

I am trying to squeeze a little more power out of my 383 LT-1 over the winter and wanted to get opinions on the 1 7/8's stepped headers and if there is a good gain over the 1 3/4. The car has a sorted out 383 LT-1. Link to most of build is here https://ls1tech.com/forums/lt1-lt4-m...l#post17795591 <-Click Link. Price difference is $200 bucks plus the stepped 1 7/8's have a three week wait time. I am not in a hurry though. I bought Kooks true duals already to get rid of the pacesetter y pipe restriction. I also need the Kooks headers so I can bolt the exhaust up. I am hoping the Kooks headers will net me a little more power over the Pacesetter long tubes as well. feel free to give any thoughts!

96capricemgr

iTrader: (1)

If the 1 3/4" headers are well built you are chasing the wrong parts. Cars can run 10s NA with 1 5/8" headers. You might make a bigger dyno number but I don't believe it will be any faster.

CamOnlyJabroni

The Kooks 1 3/4 look a lot nicer that the Pacesetter headers as far as the merge and the primaries. As you would figure considering the cost difference. When the motor went in last year I spent a few hours grinding down the welds on the Pacesetters primaries where they meet the heads. I don't think the Pacesetters even have a merge spike. I never checked when I had them off last. I am mainly doing this cause the Kooks true duals won't directly fit with the Pacesetter headers. I am doing all of this to take my electric cutout and Pacesetter y pipe out of the equation. Only reason I am doing away with the electric cutout is even with a turn down I didn't like the exhaust getting all over the bottom of my car. Yes I keep my old junk LT-1 f body car that clean to where I care about that kind of thing.

96capricemgr

iTrader: (1)

LT1

LT-1 is like 1970 engine.

94FBIRD

iTrader: (5)

This! Went from 1 5/8 MACs to the Kooks 1 3/4s and gained 2 mph in the 1/4mile, but the ET did not improve. I had to get the Kooks, because after 16 years the MACs rusted through. The stepped headers might not make much difference. I went with the 1 3/4s because of the (then) $300 price difference

Apparently, for me, the long tubes didn't change my low-end torque enough to improve ET.

96capricemgr

iTrader: (1)

Bigger primaries might make plugs harder to change too so there are considerations beyond $200 price difference.

nitrous2fast

iTrader: (2)

Your problem is that when you changed to the larger primaries your torque curve shifted higher in the rpm band. With no converter change that would result in 1- the motor produces a bit more power up high 2- now produces less torque at the same rpm below say 3500 rpms 3- the converter is now not flashing high enough to hit the top of the torque curve.

Ed Wright

iTrader: (1)

It depends on how much power you are making. If you are much over 450 RWHP the 1 7/8" would probably be faster. Otherwise the 1 3/4" to 1 7/8" stepped would likely be faster.
Only 400 RWHP? Probably 1 3/4".
Been my experience with my car.

kinglt-1

iTrader: (26)

+2mph indicates a 20hp increase...just because you did not et any better does not mean much...that could be in your suspension or converter setup.

CamOnlyJabroni

I think I will just get the stepped 1 7/8's. A couple hundred bucks is pretty much moot at this point anyway. If I hit it with a big shot in the future, at least I will know I have plenty of flow out the exhaust. Especially being mated to the Kooks true dual exhaust.

96capricemgr

iTrader: (1)

I am not buying a 20hp gain from 1 5/8 to 1 3/4 primaries.
I mean hell that is all manifolds to headers is worth.

I believe bowtienut went from 1 5/8 tri-ys to 1 3/4 4into1 on an already 10 second NA car and saw little to no difference and with the 8" ATI I don't want to hear the converter cop out.

94FBIRD

iTrader: (5)

I get what you're saying...just that everything I've read is that longer primaries increase low-end torque. Therefore, any top-end gain I received did not translate into better ETs, only MPH.

94FBIRD

iTrader: (5)

I re-read my post and it was a little confusing. I was trying to say that OP is not going to see big improvement in his performance from going from his Pacesetters to the 1 3/4 to stepped 1 7/8 headers. The main benefit being that they will not very rust-out.

kinglt-1

iTrader: (26)

I do not think Josh expects a big improvement per his original post. The biggest gain will be ditching the shitty pacesetter merge. He bought a set of Kooks True Duals for a good price and needs Kooks headers for proper fitment. He simply asked which header to go with (stepped 1 7/8 or non stepped 1 7/8) and somebody had to derail the thread(post #2) instead of answering the question.

CamOnlyJabroni

I am definately not expecting to see a big increase considering the fact that I already have 1 3/4 Pacesetters on the car. I just wanted some opinions on stepped 1 7/8's vs 1 3/4 in Kooks so I could weight the $200 price difference vs. There being a potential at having more power. I have to buy Kooks now because I have their true dual setup and want it to bolt up with minor to no modification. I do expect to pick up some power taking the pacesetters y pipe merge out of the equation though. I have seen a handful of lsx cars with dyno sheets back to back and saw very impressive gains with a better merge.

96capricemgr

iTrader: (1)

Are you considering the likely further compromised plug access?
Maybe the difference is next to nothing, heck maybe they were designed later with "lessons learned" and improve access.
There is more to consider than bigger is better and only $200.
You seem interested in a thoughtful decision even if others aren't.

cardo0

Derail? What can u mean derail with great info someone somewhere said so. We, us, most of us, well heck everyone knows for fact that maybe the 1&7/8" stepped pipes may possibly have some issues. Gonna need to plot the new torque curve and buy a new converter with those pipes too - someone on a blog somewhere that knew someone with those headers said so.

Ed Wright

iTrader: (1)

As I mentioned, it's related to how much power your making. My 383" loved 1 7/8" with 3.5" collectors compared to 1 3/4". I was foot braking then. Most Stock Eliminator (foot brake) LT1 cars I see use steped 1 3/4"-1 7/8" steped with 3" collectors. On the engine dyno my 350" SS engine made more torque below 5200 with the 1 3/4"-1 7/8" steps, but less power from 6000 & up. If I was foot braking the car, I'm sure the 13/4"-1 7/8" stepped would be quicker. Mine hates 3" collectors big time. I use a Trans brake, and my converter hits at 6200. It likes 1 7/8" with 3.5" collectors. They are worth 15 hp above 7000 RPM. With a factory PCM's 7000 RPM limitation, and using a foot brake (lower stall) I don't see a sub-500 RWHP car running quicker with 1 7/8" headers. Btw, merge collectors are supposed to be the hot set up now. Tested two sets of those on my car, it took some tuning (fueling) changes to get one set equal to my straight collectors. The smaller choked set never got there. They appear to me to be more beneficial to a foot braked car as well. Hope some of this helps.
Btw, with 1 7/8" Hedman Hustlers, forget changing #5 plug without unbolting the header.

CamOnlyJabroni

Well the 1 7/8's are stepped so I don't see why they would be any harder. Hell my spark plug socket with a open ended wrench and a gear wrench make spark plug changes pretty easy. Easy enough to change them every other oil change.

CamOnlyJabroni

I just ordered the Kooks 1 3/4 to 1 7/8 x 3 stepped race headers. When I get it all together I will post a video showing how it sounds and runs with the Kooks true duals. Thanks for all who replied. Thanks for posting up ED!. I will see how much power it makes when it goes on the dyno in the Spring. 11.5:1 230/236 .510 .520 114LSA custom XE lobe rated on 1.5 rockers, Comp High Tech Stainless 1.7 rockers, LPE hand ported stock castings. NOT THEIR OLD CNC DESIGN, Mahle -9cc piston, port matched intake, 58mm bbk throttle body.