LT1 intake....siamese runners?
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Joined: Apr 2001
Posts: 2,195
From: Springfield, IL
LT1 intake....siamese runners?
cutting out the runner divider...
any benefit?
little more volume?
anyone done it?
some TPI setups seem to benefit from it.....would the LT1?
wouldnt be hard too do! would make porting a bit easier
any benefit?
little more volume?
anyone done it?
some TPI setups seem to benefit from it.....would the LT1?
wouldnt be hard too do! would make porting a bit easier
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Joined: Mar 2001
Posts: 2,521
From: Costa Mesa, CA
Re: LT1 intake....siamese runners?
That's an interesting idea! It seems like you wouldn't want to take out the whole divider, but I wonder how much of it would be optimal (if it would show a gain) to take out. This would be a good advanced tech topic, in my opinion.
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From: Springfield, IL
Re: LT1 intake....siamese runners?
Originally Posted by FastZinTennessee
That's an interesting idea! It seems like you wouldn't want to take out the whole divider, but I wonder how much of it would be optimal (if it would show a gain) to take out. This would be a good advanced tech topic, in my opinion.
what part of the divider being left in would be beneficial, at the beginning of the runner (entry) or end of the runner (exit)? and why?
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From: Costa Mesa, CA
Re: LT1 intake....siamese runners?
Originally Posted by simple
what part of the divider being left in would be beneficial, at the beginning of the runner (entry) or end of the runner (exit)? and why?
If you took out the whole divider wouldn't you have cylinders fighting eachother for air? With the runner you are simply setting aside more of a volume of air for whenever the cylinder draws it in right?
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From: Springfield, IL
Re: LT1 intake....siamese runners?
the cylinders that would be siamesed, wont be the ones firing at the same time or firing in sequence...
with the divider completely removed, a gain in volume would be there but how much and is it worth it...?
it seems like only the runners on the back side of the divider would gain from the removal tho since there wouldnt be any change too the intake for the cylinders that are on the front side of the divider....altho the added room with the divider removed might aid in porting of that area for those cylinders...??
with the divider completely removed, a gain in volume would be there but how much and is it worth it...?
it seems like only the runners on the back side of the divider would gain from the removal tho since there wouldnt be any change too the intake for the cylinders that are on the front side of the divider....altho the added room with the divider removed might aid in porting of that area for those cylinders...??
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Joined: Mar 2001
Posts: 2,521
From: Costa Mesa, CA
Re: LT1 intake....siamese runners?
Keep in mind that a gain in volume takes away from velocity of airflow, holding all things else equal. I'm not necesarily talking about plenum volum, but you're turning two runners into one, and I'm honestly not sure how they'll react. I have seen siamesed runners for the TPI like you were talking about, but that's a vastly different set up to start out with.
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Joined: Sep 2000
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From: Winnipeg,Mb,Canada
Re: LT1 intake....siamese runners?
Originally Posted by FastZinTennessee
Keep in mind that a gain in volume takes away from velocity of airflow
My thoughts exactly. By removing the majority of the divider would that not cause a whole lot of turbulance at the intake/head transition point?
I would think that the amount of divider you would need to keep to provide velocity and smooth airflow would negate any gains in the first place.
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Joined: Oct 2002
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From: Upstate NY
Re: LT1 intake....siamese runners?
1)You lose intake tuning. LT1 runners are too short now, and you make it worse.
2) Air will have a 3-sided runner with only a 'virtual' wall on one side which might disrupt flow. You could verify this on a flowbench with a modified manifold.My guess is worse flow, not better.
3)Fuel may have a hard time deciding where to go because it will now be sprayed into one side of the siamese port and not directly into an individual cylinder port. The consecutive firing cylinders (5 & 7) will probably be the worst.
I'm trying to think of the up side....nothing much comes to mind.
Siamesed runners for TPI were in the upper portion of the manifold, right? That was done to shorten the overall intake tract length to something around 5-6 inches from more like 16+.
Look around for other modern (post 1950s) intake manifolds for NA engines that use siamesed runners. Study them and how they improved engine performance. BTW, post the list. I'm interested.
My $.02
2) Air will have a 3-sided runner with only a 'virtual' wall on one side which might disrupt flow. You could verify this on a flowbench with a modified manifold.My guess is worse flow, not better.
3)Fuel may have a hard time deciding where to go because it will now be sprayed into one side of the siamese port and not directly into an individual cylinder port. The consecutive firing cylinders (5 & 7) will probably be the worst.
I'm trying to think of the up side....nothing much comes to mind.
Siamesed runners for TPI were in the upper portion of the manifold, right? That was done to shorten the overall intake tract length to something around 5-6 inches from more like 16+.
Look around for other modern (post 1950s) intake manifolds for NA engines that use siamesed runners. Study them and how they improved engine performance. BTW, post the list. I'm interested.
My $.02
