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Discussion Starter #1 (Edited)
have a 21' spectra v-drive with a 750ish HP twin turbo LS6 engine that still has the original "winters" aluminum manifold on it.
i want to put a taller intake on it for a couple reasons....
1) intake tubes that go from turbos to the intercooler need to come up so they can clear the taller valve covers i have.
2) better performance
3) aesthetics

i have a strip dominator but was told by the guys at the carb shop not to use it because i would loose the ability to pull skiers and getting up on plane quickly because it's designed to work in the 4500-8500 rpm range.
so i'm looking for a happy medium manifold that works well in the 2500-6500 rpm range.
 

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any pics of the engine ?

S CP
 

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Discussion Starter #4
i'm about to strip the motor down to a long block and send everything out for polishing and want to buy the new intake so i can send it out with it.
i need to change some plumbing anyway and all the turbo stuff is in the way so i figured since i have a month till my next river trip i might as well polish everything, and re-assemble with fresh gaskets while i have it all off.
 

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Discussion Starter #6
Thats a low profile alumn manifold. Even the stock L88-LS 6 manifold would add height. Problem is, the price on them is stupid in todays market.
I would go with a Edelbrock Air Gap. If that not enough height, add a 4 hole spacer.
all the air gaps i see are oval port.
the casting number on the manifold is 3963569 LS6 "winters" is what keeps coming up.
the original owner said he bought a 454-450HP LS6 motor and swapped the pistons out so i'm pretty sure its an ls6 intake.
 

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steelcomp was here
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If you're running a 4150 flange, I'd get a Victor Jr. No need to run a dual plane.
 

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all the air gaps i see are oval port.
the casting number on the manifold is 3963569 LS6 "winters" is what keeps coming up.
the original owner said he bought a 454-450HP LS6 motor and swapped the pistons out so i'm pretty sure its an ls6 intake.
Edelbrock 7562 is a non polished air gap for reg heads. 75624 is an Edurashine, and the 75621 is polished.

If you're running a 4150 flange, I'd get a Victor Jr. No need to run a dual plane.
It will gain nothing over the air gap on that setup. Will hurt low end? I have no idea. But it will gain zip.



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Discussion Starter #9
If you're running a 4150 flange, I'd get a Victor Jr. No need to run a dual plane.
might as well just run the Holley Strip Dominator that i already have then.

are you 100% sure that i wont loose all my low end torque with a huge single plain?
 

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Thats a low profile alumn manifold. Even the stock L88-LS 6 manifold would add height. Problem is, the price on them is stupid in todays market.
I would go with a Edelbrock Air Gap. If that not enough height, add a 4 hole spacer.

I was thinking that....when the engine isn't under boost does the intake help all that much?

S CP :D
 

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might as well just run the Holley Strip Dominator that i already have then.

are you 100% sure that i wont loose all my low end torque with a huge single plain?
I have no idea. But you be sure to get back to us if it gains a single MPH, or get there a .10 of a secind faster. But I won't hold my breath.And thats over the manifold you running now.

It may be a LS 6 manifold, but in that shot is sure looks flatter to me than this.




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Discussion Starter #12
I have no idea. But you be sure to get back to us if it gains a single MPH, or get there a .10 of a secind faster. But I won't hold my breath.And thats over the manifold you running now.

It may be a LS 6 manifold, but in that shot is sure looks flatter to me than this.
much flatter and that one has a different casting number on it as well.
 

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might as well just run the Holley Strip Dominator that i already have then.

are you 100% sure that i wont loose all my low end torque with a huge single plain?
There are two design functions of an intake manifold; 1) provide good air signal to the carb, and 2) provide enough airflow and fuel distribution to feed the engine effectively. Once you remove the need for a good air signal to the carb (because you have turbo's in the way ans you're boosted), then all you really need is enough runner volume to feed the engine. A dual plane intake has one purpose, and that's to provide as strong a signal to the carb as possible, with airflow and runner design being second consideration. No need for a dual plane when carb signal is not a consideration. The next consideration is fuel distribution and airflow. Keeping the intake runners on the smaller side will help maintain some runner velocity and help with cylinder filling, even with boosted engines. You don't want to get too big of an intake on there, but in this case, where carb signal isn't a consideration, I think the Holley would be fine. The "it's made for X rpm" thinking only has to do with carb signal performance. I think the Vic Jr is a better intake form an air and fuel distribution standpoint, but not to the extent that I'd get rid of the Holley and buy the Edelbrock. Either are going to suit your needs just fine.
I hope that's not too confusing.
 

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There are two design functions of an intake manifold; 1) provide good air signal to the carb, and 2) provide enough airflow and fuel distribution to feed the engine effectively. Once you remove the need for a good air signal to the carb (because you have turbo's in the way ans you're boosted), then all you really need is enough runner volume to feed the engine. A dual plane intake has one purpose, and that's to provide as strong a signal to the carb as possible, with airflow and runner design being second consideration. No need for a dual plane when carb signal is not a consideration. The next consideration is fuel distribution and airflow. Keeping the intake runners on the smaller side will help maintain some runner velocity and help with cylinder filling, even with boosted engines. You don't want to get too big of an intake on there, but in this case, where carb signal isn't a consideration, I think the Holley would be fine. The "it's made for X rpm" thinking only has to do with carb signal performance. I think the Vic Jr is a better intake form an air and fuel distribution standpoint, but not to the extent that I'd get rid of the Holley and buy the Edelbrock. Either are going to suit your needs just fine.
I hope that's not too confusing.
This is true. The turbos do more to kill your low end than a single plane can, and even with a single plane, the loss is no greater because of the manifold. The loss of signal still rests with the location of the carb in relationship with the manifold.

Steel is right. I doubt you would loose any noticable low end.
That said, that setup won't gain from single plane either. Nature of the beast. A simple 4 hole spacer will raise the carb, or you could try your Holley Strip Dominator.
In the end, all your doing is raising the carb. Your not changing the performance much one way or another.



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Discussion Starter #15
There are two design functions of an intake manifold; 1) provide good air signal to the carb, and 2) provide enough airflow and fuel distribution to feed the engine effectively. Once you remove the need for a good air signal to the carb (because you have turbo's in the way ans you're boosted), then all you really need is enough runner volume to feed the engine. A dual plane intake has one purpose, and that's to provide as strong a signal to the carb as possible, with airflow and runner design being second consideration. No need for a dual plane when carb signal is not a consideration. The next consideration is fuel distribution and airflow. Keeping the intake runners on the smaller side will help maintain some runner velocity and help with cylinder filling, even with boosted engines. You don't want to get too big of an intake on there, but in this case, where carb signal isn't a consideration, I think the Holley would be fine. The "it's made for X rpm" thinking only has to do with carb signal performance. I think the Vic Jr is a better intake form an air and fuel distribution standpoint, but not to the extent that I'd get rid of the Holley and buy the Edelbrock. Either are going to suit your needs just fine.
I hope that's not too confusing.
thanks for taking the time to type all of that....

since you seem extremely knowledgeable in air/fuel delivery i have a few more questions for you.

1. why did the guy at the carb shop who seems very knowledgeable in air/fuel delivery as well tell me that i would hate that manifold and not to run it.
2. what about when i'm not making any boost like in the idle-2000 rpm range.
3. do you think an air-gap would suit me better than the holley? i know someone that has one for $100 and i can sell the holley to make up the difference.
 

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Discussion Starter #16
never mind questions 2-3 were answered as i was typing apparently.

so back to number 1 ... why did a professional carb designer/builder/or whatever he is tell me what ever i did not to use a single plain manifold as he was staring at my engine?

kinda strange right?
 

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thanks for taking the time to type all of that....

since you seem extremely knowledgeable in air/fuel delivery i have a few more questions for you.

1. why did the guy at the carb shop who seems very knowledgeable in air/fuel delivery as well tell me that i would hate that manifold and not to run it.
2. what about when i'm not making any boost like in the idle-2000 rpm range.
3. do you think an air-gap would suit me better than the holley? i know someone that has one for $100 and i can sell the holley to make up the difference.
1. His basic thinking was correct...when you're considering a carbureted engine. Since I wasn't there for the conversation I really don't want to second guess anyone, I just disagree with the comment in this application. If you were to say you wanted to try a Super Victor or something huge like that, I might agree, but the Holley really isn't a "big" intake.
2. You still have turbo's in the way of any real air signal to the carb, and with the plenum box, those long tubes, and the turbo's, I don't think it's much going to care what intake is on it at idle or at 2000rpm.
3. I think there will be a performance gain with a small single plane over a dual plane, but it will probably be minimal with your appplication.
 

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1. His basic thinking was correct...when you're considering a carbureted engine. Since I wasn't there for the conversation I really don't want to second guess anyone, I just disagree with the comment in this application. If you were to say you wanted to try a Super Victor or something huge like that, I might agree, but the Holley really isn't a "big" intake.
2. You still have turbo's in the way of any real air signal to the carb, and with the plenum bos, those long tubes and the turbo's, I don't think it's much going to care what intake is on it at idle or at 2000rpm.
3. I think there will be a performance gain with a small single plane over a dual plane, but it will probably be minimal with your appplication.
TT, Steel is dead on. If there is a gain, it will be small. But that wasn't your concern when you started this thread, it was height.
The little plenum increase from a single plane is nothing compared to the volume from the intake valve to the carb in your setup. Look at all the volume the carb sees from the plenum under it, to the intake valve. The Holley just is not going to effect that all that much.
If it was me, and all I wanted, knowing a manifold will not increase my power any great amount, I would throw on the Holley if I had one, or throw on a spacer if all I wanted was extra height. No reasonable manifold is going to make much difference, good or bad.



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