1 7/8 LT's on a SI LS1?
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Joined: Jul 2005
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From: Ft. Wayne, IN
1 7/8 LT's on a SI LS1? I have been reading up on which LT header 1 3/4 or 1 7/8 makes more power on a stock internal ls1. It seems the most recent posts show that the 1 7/8 still show gains. My concern is I just ordered a set of kooks 1 7/8 LT's w/ the kooks 3" true dual setup. It will take 2-4 weeks to complete, so I can still change if need be. My logic on purchasing the 1 7/8 was to leave room for growth. Right now Im just normal bolt-ons other than 1.85 rockers/918 springs. I will be installing a fti 3800 converter when the exhaust gets installed. Next mod in the future will be a n2o outlet wet plate or the whipple 2.9 f-body kit, when and if it's released...other than that Im pretty much plan on staying stock internal...I might do a small cam but most likely not. So am I on the right track or should I change the order to the 1 3/4 LT's? Thanks
Last edited by kinglt-1; Oct 4, 2011 at 01:09 AM.
It won't hurt anything going with the 1-7/8" primaries at this point - I've been running them on my bolt-ons only '02 Camaro for the better part of the past two years. Prior to that, I was running Kooks 1-3/4" headers. The 1-7/8" primaries are a bit tighter, but everything still cleared just fine, and the install went smoothly. As an added bonus, the collectors ended in the same spot, so I bolted my existing exhaust right up and was on my way.
Performance-wise, I didn't really notice anything one way or another, but wasn't really expecting to (I didn't do a back-to-back dyno though). It'll definitely leave me room to grow down the road, and that's what I was really after.
Performance-wise, I didn't really notice anything one way or another, but wasn't really expecting to (I didn't do a back-to-back dyno though). It'll definitely leave me room to grow down the road, and that's what I was really after.
I wish I would have went with 1 7/8 when I bought mine years ago. From talking with my tuner the 1 3/4 don't really become a restriction until around 440 rwhp, but i've never heard anything negative about 1 7/8 on a bolt-on car. I just did H/C so I'll be switching soon.
Thread Starter
Joined: Jul 2005
Posts: 5,898
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From: Ft. Wayne, IN
Thanks for the replies! I have hooker 1 3/4 now and they are about rusted out and the car never sees rain or snow lol. I figured might aswell get the stainless 1 7/8 and never buy headers again. My only concern, which is why I post this thread,, because a well repected member(Mr. Tony Mamo) posted in a older thread that they would hurt tq significantly in the lower rpms. But then texas speed did a dyno comparison between thier 1 7/8 vs pacesetter 1 3/4 and they picked up power everywhere. I leaning towards it being a myth, just like the fast 102 hurting power on a 346 myth that was busted.
Thanks for the replies! I have hooker 1 3/4 now and they are about rusted out and the car never sees rain or snow lol. I figured might aswell get the stainless 1 7/8 and never buy headers again. My only concern, which is why I post this thread,, because a well repected member(Mr. Tony Mamo) posted in a older thread that they would hurt tq significantly in the lower rpms. But then texas speed did a dyno comparison between thier 1 7/8 vs pacesetter 1 3/4 and they picked up power everywhere. I leaning towards it being a myth, just like the fast 102 hurting power on a 346 myth that was busted.
Part throttle isn't as crisp to me as it was with the 1-3/4" headers, but that isn't something that would show up on a dyno since a dyno only shows WOT. I don't miss it much since my 4.11s out back make traction an issue by itself, and I also have a fairly lightweight clutch assembly that makes things a bit peppier too around town.
I didn't buy them for the engine currently in my car (like I said - bolt-ons only), but for the engine I'm planning to build on down the line. Any gains/losses switching between the two wasn't enough for me to be concerned, and I wouldn't hesitate to do it again.
I didn't buy them for the engine currently in my car (like I said - bolt-ons only), but for the engine I'm planning to build on down the line. Any gains/losses switching between the two wasn't enough for me to be concerned, and I wouldn't hesitate to do it again.
Thread Starter
Joined: Jul 2005
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From: Ft. Wayne, IN
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Thread Starter
Joined: Jul 2005
Posts: 5,898
Likes: 255
From: Ft. Wayne, IN
Part throttle isn't as crisp to me as it was with the 1-3/4" headers, but that isn't something that would show up on a dyno since that is WOT only. I don't miss it much since my 4.11s out back make traction an issue by itself, and I also have a fairly lightweight clutch assembly that makes things a bit peppier too around town.
I didn't buy them for the engine currently in my car (like I said - bolt-ons only), but for the engine I'm planning to build on down the line. Any gains/losses switching between the two wasn't enough for me to be concerned, and I wouldn't hesitate to do it again.
I didn't buy them for the engine currently in my car (like I said - bolt-ons only), but for the engine I'm planning to build on down the line. Any gains/losses switching between the two wasn't enough for me to be concerned, and I wouldn't hesitate to do it again.
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Does anybody have links to the comparisons?
I am also running Pacesetter 1 3/4" headers that were on the car when I bought it. They are rusting away and Id like to swap to a set of stainless steel. I figure I would bump up to 1 7/8" if it would be worth it tho. I'm currently around 410whp on a stock bottom end LS1. I don't want to lose low end just to gain a tad bit of mid and top end, so visual comparisons would help me decide.
I am also running Pacesetter 1 3/4" headers that were on the car when I bought it. They are rusting away and Id like to swap to a set of stainless steel. I figure I would bump up to 1 7/8" if it would be worth it tho. I'm currently around 410whp on a stock bottom end LS1. I don't want to lose low end just to gain a tad bit of mid and top end, so visual comparisons would help me decide.
Thread Starter
Joined: Jul 2005
Posts: 5,898
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From: Ft. Wayne, IN
https://ls1tech.com/forums/dynamomet...s-1-7-8-a.html
https://ls1tech.com/forums/generatio...o-results.html
https://ls1tech.com/forums/generatio...o-results.html
Last edited by kinglt-1; Oct 4, 2011 at 07:18 PM.
I love the 1 7/8 on mine. It defintely does NOT lack for tq down low... It snaps your neck when you nail the throttle. Of course the stall helps that, but the engine is making mad tq.
Thanks for the links I read both threads and they were helpful. Id still like to see dyno comparisons for small bore 346's to better help me decide. Ill most likely go with the 1 7/8" after a little more research.
Thread Starter
Joined: Jul 2005
Posts: 5,898
Likes: 255
From: Ft. Wayne, IN
no prob...if you find some more good links post them up!
Last edited by kinglt-1; Oct 5, 2011 at 08:50 PM.
