1 7/8 LT's on a SI LS1?
10-04-2011, 12:40 AM
#1
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; 10-04-2011 at 01:09 AM.
10-04-2011, 07:49 AM
#2
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.
10-04-2011, 08:14 AM
#3
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.
10-04-2011, 09:45 AM
#4
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.
10-04-2011, 10:35 AM
#5
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.
10-04-2011, 11:00 AM
#6
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.
10-04-2011, 11:05 AM
#8
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.
10-04-2011, 12:56 PM
#10
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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.
10-04-2011, 06:57 PM
#11
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; 10-04-2011 at 07:18 PM.
10-05-2011, 11:02 AM
#15
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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.
