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Vortec 8.1L Go Fast Parts
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103 Posts
Discussion Starter #1
We're just finishing up the design phase for the new Raylar 90mm cast manifold for the 8.1L engine, figured you all might like to see it.



With this manifold, you will be able to switch to a LS2 90mm throttle body / LS truck 90mm throttle body depending on your existing connector. In addition to the larger throttle body, we've improved air flow with better runner design and a larger plenum.
 

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4,725 Posts
very nice, how much?
 

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Vortec 8.1L Go Fast Parts
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103 Posts
Discussion Starter #5
The Raylar Cool Gap manifold is the only difference between the marine and street packages. Our truck stage 2 package produces 527hp / 581ft-lbs of torque with the modified stock intake manifold, but in the marine application makes 540hp / 601ft-lbs. So with our smaller BP-203 cam and heads, you're looking at a gain of 13hp & 20ft-lbs. You'll make even more with the BP-206 and BP-213.

The main restriction on the Cool Gap is that tiny stock 78mm throttle body. The new cast manifold's larger throttle body means more air is entering the engine (1150CFM vs 800CFM). In LS engines, gains of 15 horses are expected with this swap. Since the 8.1L engine is much larger, I would expect to see closer to 20hp.

So - we don't know exactly how much power the intake manifold will produce, but probably somewhere in the neighborhood of 30hp / 25 ft-lbs. Possibly more with the more aggressive cams / packages. When we get the first manifold (still probably a month or two out), we're putting it on the 540 stroker in the Suburban and should have dyno figures pretty quickly thereafter.

No pricing is set yet, but the goal of making the cast manifold versus hand welding each unit out of aluminum (Cool Gap) is to bring the cost down and improve air delivery.

We're very excited for this manifold, but not just for cost savings. Our designer was Toyota Racing Development's lead racing parts designer for over a decade and tossed a lot of his NASCAR / IndyCar knowledge into this manifold's plenum, bell mouths and intake runners.
 

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A composite/plastic production model would be awesome for weight savings.

Food for thought
 

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Lighter intake, heads, exhaust, etc all make a large cumulative difference.
 

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Doubtful on a big block.
 

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Vortec 8.1L Go Fast Parts
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103 Posts
Discussion Starter #16
We thought about doing it in plastic, but its boring and ugly. Aluminum lends itself to a wider variety of applications. For the go fast crowd as-cast aluminum will be fine, but the show truck guys can polish theirs to a shine and the marine crowd can powder coat them for appearance and easy cleaning.

In time, the two piece 90mm manifold's base will be used for a velocity stack setup as well. Larry's favorite motor was the HO750 with its polished billet throttle body plate and polished aluminum velocity stacks - only downside was that each manifold cost 30k. This new manifold gives us the ability to cut that cost down greatly and produce some really neat induction options for the 8.1L that flow more than enough air. For those wondering what the HO750 looked like:



You'll get much better weight savings out of a 496 / 8.1L getting rid of the 90lb (each) cast iron heads! Moving those things around the shop will replace your need for a gym membership.
 

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boosted gasser dually
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6 Posts
Micah, love how your representing Raylar and giving their customers the respect they deserve. Big upgrade in customer service. Look forward to meeting you when I have the $$$ for a 540 stroker kit.
 

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boosted gasser dually
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6 Posts
Ztroyer, I apologise for lack of photos and have to admit, having a hard time with technology. We'll try to post pics of truck tomorrow.
Cheers.
 

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Vortec 8.1L Go Fast Parts
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103 Posts
Discussion Starter #20
Thanks Kiwi, just trying to get the information out there. There are too many "8.1L?? - throw that thing out" articles on the internet from LSX guys who don't understand what these motors are capable of.

On our prototype, the plenum is one piece and all of the runners are a separate piece that bolt together. We'll probably keep the same design for the production manifold.
 
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