You guys are killing me with this heat soak issue. As I have stated before all performance intakes until recently have been aluminum. LSX manifolds do not have hot coolant running through them nor do they have hot oil splashing on the bottom like a SBC does. They only reason auto manufactures came up with the plastic or composite manifolds initially is for weight and cost of materials. They were able to do this because of the fact that there is no coolant or oil coming in contact with the manifold. Here is a quote I found on the web from years back about the new GEN III LS6 motor.

"A unique item of Gen IIIs is the composite ("plastic") intake manifold. Plastic intakes are great for car companies because of low mass, low cost of materials and cheap manufacturing. The downside, a big difference between them and aluminum or iron manifolds, is the high cost of tooling. Car companies justify that by spreading it over a huge run of parts. As the LS1 went to production, GMPT already knew more performance would come from a revised intake manifold, however, the cost of retooling was so high, it waited for the next iteration of the complete engine to make the investment. Cost is, also, why the performance aftermarket has, to date, not offered intake manifolds for the Gen III."

It is true that the aluminum is hotter to the touch but nobody has proof about the actual intake temp inside the manifold. Aluminum is used for heat sheilds for a reason. It is a great heat barrier. The heat in question is from the outside of the manifold not inside where the airflow is. Not to mention that the cold air from outside only spends about 1 second going through the manifold. A microwave can't even heat something in that amount of time. How much HP do you really think you loose even if the manifold was 50* hotter? If you spray nitrous like I do it would negate any argument anyway due to how cold nitrous is. Heat soak is a reality but it's actual effect on how much HP you loose on these motors is very minimal in my opinion. I would love to see Mythbusters try this one out. Below are some pics of the inside of my BBK manifold followed by a crude cutaway of an LS6. Notice how the LS6 uses posts or braces in the middle of the manifold to strengthen it. That can't be good for smooth airflow. I'm not knocking the LS6 by any means. I think it is a great manifold. I'm just tired of hearing about heatsoak. In my opinion the only disadvantage to the aluminum ones is weight. The BBK weighs in at about 25lbs whereas the FAST 90 is 11lbs. Not sure on the LS6 but 14-15lbs isn't really that much when you consider the fact that it has a 85mm opening vs. 78mm for the LS6. I also belive the plenum and runners are bigger and you have the ability to polish the outside as well as port the inside for even more gains.

 

Somebody PLEASE dyno test one of these things against a LS6 intake, I wanna see some #'s!!!!!

 

im having the same delema can someone send a link to a bbk pic and price?

 

For the price of the BBK aluminum intake and BBK throttle body you'd be better off buying a FAST 90 and Nick Williams throttle body.

 

Jesus people. These intakes do suffer from heat soak and it does hurt performance. Just because there is no coolant or oil running thru it doesn't mean it doesn't get hot. And Aluminumk is NOT a heat barrier its the exact opposite. it is very good at taking in heat and disipating it that is why its used for heat shielding. And i'll give you one guess as to where the aluminum disipates the heat..... INTO THE AIR THAT COMES IN CONTACT WITH IT! You say it only spends a second going thru the intake and thats not enuff time to heat up huh? well by that theory radiators weouldn't work at all cause air flows thru them pretty fast too.
It has been proven that icing down your intake WILL make your car faster because the motors heat that gets transfered into the intake heats the incoming air. Now would you rather have an intake that takes in alot of heat (aluminum) ar one that doesn't take in as much heat (composite)?
And i think it is just HILARIOUS that you think the aluminum intake is just hot on the outside and not the inside. when any metal gets hot the heat spreads evenly from where it begins in this case the heads. with aluminum heads touching an aluminum intake the intake will slowely but surely reach the same temperature as the heads.

 

where can i get a bbk?

 

I heard the bbk ssi dont seal that good

 

I'm going to agree with SUX2BU on this on.

Your logic seems totally the wrong way round.

Most of the heat in a alumimiun intake is going to have come fro the rest of the engine, which it is mounted on.

Also aluminium conducts heat very well. Why else would they make heat sinks out of it?

http://www.debbiesrcworld.com/lrp31800_z18s_PS.jpg
http://www2.propichosting.com/Images/421565218/48.jpg

Also air doesn't need to be in the intake for very long. Else how would a heater work in a car. That is just cold outside air pushing thru a chamber which has been heated by the engine, and thus hot air.

Or even simpler, a hair dryer. Cold air moves at speed over some hot elements and ta-da! hot air.

And weight is weight, but worse than that, it will also raise the centre of gravity due to where the intake is located, i.e. on top of the engine.

Oh BTW you can port composite manifolds too.

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To the original poster, IMO I say go LS6, or if big plans are in your future then the FAST 90/90 setup.

Unless it's a show car and you want something shiny on top of the engine that is.

Oh yeah for futher proove, many exoctics and race cars (circuit) will normally use composit or carbon fibre intakes, not almuinium.

*changed huge pictures to links.

 

It does sorta look like a giant heat sink.

I'm trying to learn something here- clearly aluminum absorbs heat very well. Would this help lower the surface temperature of the heads? I'm not saying this would make this manifold more beneficial but that's a lot of aluminum bolted to the heads. A what about the heat transfer to the throttle body? That can't be good.

 

Not to throw fuel on the fire, but the last time I put my hand on an LS6 intake while the engine was running.........IT WAS HOT!!!

 

I've also done this. A composite intake does not get very hot. Try touching an aluminum intake and see if you can tell a difference!

 

I think you may need to clarify what you mean by HOT.

If it's still touchable then it ain't hot!

An aluminium one will certainly be painful to hold your hand on and probably quite damaging to yourself.

 

It was as hot as the valve covers. I can try a surface temp comparison with a probe for exact results...the tips of my fingers aren't accurate enough to give a good comparison.

 

No way that a plastic intake would be as hot as aluminum valvecovers. I've worked on PLENTY of cars that just came rolling in and while all the intakes have been warm (maybe even a little uncomterable on a hot summer day with a stock thermostat car) they have never been hot enough to burn you like valvecovers, headers and heads.

 

I guess your right the air won't get hot its only in contact with the intake for a few seconds. You better tell all the people with superchargers/turbo chargers to throw away there intercoolers because the air flowing through the intercooler is only there for a split second. My SS camaro would get a lot of heatsoak from the air flowing through the hood(not even in contact with the motor) and now my IAT's (intake air temp.) dropped 15-20* changing over to the Fast toys ram air.

-William

 

I've grabbed enough hot stuff in my life. Neither the intake (ls6) or the valve covers were hot enough to burn my hands, but I wasn't "holding" them. I only happened to touch them since I had just come back from a ride and decided to check something. I remember thinking the intake was hotter than I expected it to be.

Headers are a completely different story. I was only brave enough to grab a hot header once. And that was after another friend grabbed them to show me the coating was that good. I still can't believe they cooled down that fast.

Moral of the story...get the aluminum intake coated.

 

Get the intake coated, so you can hold all that hot air in and make heatsoak even more of an issue??? No thanks. I don't know what the debate is about aluminum vs. composite. It's a known fact that aluminum will conduct and hold more heat. The valve covers will be hotter than the composite intake, no testing needed.

 

The coating would keep the hot Al from heating the incoming air.

 

after 2 pages there is nothing more than opinions being tossed back and forth, just as i figured

i dont think with all things being equal other than the material of the intake that there is a measurable difference in hp between the 2

 

And yet another opinion....

Guess I might as well throw in another one as well...I think both of them are pretty similar when cold. The thing is, aluminum heats up real quick.