Much like carburetor and throttle body spacers, these manifold isolators
reduce the transfer of heat from the block to the manifold.

I'm wondering how much of an effect (if any) these isolators would have on
performance and intake charge temperature.

I have "loosely" calculated about 4 milliseconds for the air charge to travel a 14 inch
path from the throttle body to the chamber (assuming 3500-6000 RPM use)

What would be the typical increase in air temperature in that period of travel?

http://www.autospeed.com/cms/article.html?&A=0401

I'm not asking because I want to install these, just sparking up some conversation
as a friend of mine is discussing the pros/cons.

FWIW, I just don't see the point.

 

Thanks Tino. And thanks in advance for any info posted. I actually enlisted Tino's help when I was asked my opinions on this. I realized I was getting in over my head and the claims that the company who manufactures the specific product I am looking at for someone just didn't make total sense. I look forward to the discussion.

EDIT: I guess I should go ahead and just give a few specifics on what I was asking Tino about. A question was purposed to me on another bored about the benefits of a spacer going between the upper and lower intake manifolds of a 3.8L fbody motor. The spacer was made of a compound to prevent heat transfer to the plenum. Here is a link to the product in question. http://www.cheetahonline.com/g3023.html There are a few more studies out there of these isolators being used with a different material called Phenolic.

 

It would probably have about as much effect as blocking off the exhaust crossover passage on a carbureted intake manifold- very slight gain to be had. I'm sure it's gotta be worth something. People don't ice down their intake manifolds at the dragstrip for nothing.

 

The cool tricks that I've seen done to standard intakes to make them keep cool is pretty amazing. Kaase did some cool tricks this year for his EM entry, phenolic intake manifold gaskets (they were delrin rings with reciever grooves cut into the intake and heads, you can do that when you have spread oval ports like a Cleveland) and a few layers to keep the lifter valley heat away from the intake. This all allowed his intake to stay at room temp during the pulls, that's definately a good idea.

Bret

 

Removing heat is always a plus, no argument there.

I'm curious about the impact of the isolators (bang for buck value).

Are we talking half a degree of intake charge temperature, or 10 degrees?

Power increases of 1 HP, or 10 HP?

Does anyone have dyno/track data from any source?

I'm wondering about the effort vs. effectiveness. From the thickness of the
isolators, it seems there might be trouble sealing and bolting down the intake
on a v-type engine.

 

Well, Tino's thinking (as I understood it) was that the air charge would be moving too fast to really be cooled down at all. However I feel that it's not cooling it down, but instead not letting it have a chance to get heated. They also sell a TB spacer that will block heat as well. So by my logic I would assume that ambient air can enter the TB with little to no temp increase. Then the charge would continue on and only pick up a slight heat elevation by having the plenum be (as some tests have shown) over 60 degrees cooler.

Without having any clue on how long it takes for an air charge to pick up any heat I would have no idea if I am correct or not. I also do not have any real good info on the properties of the materials used to find out how well they do against blocking heat.

But no one sees any real problems or concerns? How about in the area of essentially raising the intake runners by a 1/2 inch?


Thanks for the input so far everyone. I look forward to more. I honestly thought that everyone would be agreeing that it was worthless..


EDIT: Tino beat me just by a little. But I am wondering the same questions. Is there any way to actualy figure it's true effectivenes to some point?

 

"Well, Tino's thinking (as I understood it) was that the air charge would be moving too fast to really be cooled down at all."

Acutally, I was thinking opposite. The air is moving so fast from an insulated TB to chamber that it wouldn't increase much in temperature from the travel
through the plenum and intake runners.

Also thinking that all sensors are pre-plenum (MAF, IAT, etc.) therefore the
computer calculations are already considered (except for chance of knock).

I'm wondering if the benefits are really worth the effort on a EFI where the
computer reads the values before the plenum. These isolators would seem
to have more of an effect on non computer engines?

 

Sounds useless, most of the heat the intake maifold is going to pick up is going to be from the coolant passages that run through it, and the hot oil that splashs the bottom of it from the lifter valley.

Niether of which this design addresses. I doubt any gain would be seen on an engine that is at operating temperature.

 

The theory behind this is really good. Cool the intake down and therefore cool the intake ait temps. This allows more dense air into the chambers. The effect may be slight but I could see it good for a few hundreths. Scottland has a good point about the oil in the valley as well as the coolant going through the intake (which is also supposed to help cool it). If you block off the coolant passages and keep the oil from hitting the intake in the valley then you'd have a great setup for the drag races. I wouldn't recommend blocking the coolant on a street car, as the metal will heat up still after time on the road. But for quick 1/4 mile blasts I think it'll be a great idea...If you can get the theory to function.

Chris

 

Ok few more points.....


Coolant can't cool down a intake manifold, 185-200 deg coolant is going to heat up a intake that is 110 degs.

Getting a intake down to room temp while the motor is running is huge deal.

If guys who are at the top of their game spend time on doing it they must have found something huh? The engine masters is a great example of this, it's been happening from the very first contest in 2002. The 2nd place motor had a phenolic valley cover that was not part of the intake, and it had intake flange adaptors made of the same stuff.

The basic point is a cooler induction system keeps the air temps down which is a denser air charge = more HP.

It's kind of why we like to run on days with a low DA..... same thing.

Bret

 

Right. I understand the theory of lower intake temps for a more dense air charge. However I guess I am looking for some kind of conclusive argument. Something that I could use to either prove or disprove it's usage. I have seen this kind of thing used as carb spacers and even mechanical fuel pump spacers. But some see this as proof that it will not work on an EFI platform. By nearly isolating the upper intake from the radiant heat of the lower intake can we argue or even theorize some sort of gain?

 

We can safely agree that there is a gain, but we don't know how much of
a gain.

I know my 1/2" wood carburetor spacer allowed me to rest my hand on the
carburetor, whereas previously, I could hear fuel perculating. There was no
chance of touching the carburetor without risking a burn.

Now I have a nicer idle because of this, but I can't say there was a noticeable
difference in 1/4 mile improvement. My average speeds and times did not
change much that day as I recall. I ran a few passes before and after installing
the spacer.

The distance from the filter element to the plenum is about 5 inches. I use
a bug catcher to channel cool air into the carburetor. I wish I had dyno
tests to measure the difference because I know there was an improvement.

It was/is peace of mind knowing my fuel bowls and fuel is much cooler, and
the metering has most likely improved as well.

If we guess 5 degrees C of heat transfer from the manifold to the incoming
charge between the TB and Intake Valve, how much of an effect will that
have on VE and power?

I'd hate to be the one to calculate this! I realize there is more than just
air temperature change. I'm just throwing out numbers as a
scenario if anyone is able to base a conclusive answer on the above values.

 

Keep in mind the effectiveness of this mod will depend on how you use your car. If it's for a street driver I'd say it's useless. I say that because it's likely your intake manifold absorbs as much heat from the underhood air when sitting at a traffic light or moving slowly than it does from the block. Your underhood air is likely very close to 200 deg. F and all that air is going to warm up your intake manifold considerably even if you have a phenolic spacer isolating it from the block.

We did try using a phenolic spacer on an engine we developed at Chrysler that used a rather large aluminum intake manifold (becoming a rarity nowadays) and there was a very small gain. I know the number was less than 2 HP on an engine that made about 400 HP at the time. I'd have to do some research to find the exact data and post more specifics. It's been awhile.

In vehicle we did some thermocouple testing and found huge effects from intaking cold air in front of the radiator but just sitting at the staging beams and idling the car for as little as 5 minutes raised the plenum air temp so high (from underhood heat transfer) that most all the gains were lost. It took most of the 1/4 mile run before our intake temperature was back within 20 deg. F of ambient.

 

Is it safe to assume that it's easier to keep something cool then it is to cool a object once it's warm? I guess I am wondering is if between this, a TB spacer and a lot of time and ice at the track would something like this be effective at removing (or actually deterring) enough heat to make a noticeable difference? I have been working on a friends 3.8 fire bird as a test car, I suppose that Maybe at some point I could run a set of tests with some temp probes and find out what I could come up with and back it up with several track runs. I'm still kind of wondering if anyone has some kind of formula that they could equate X amount of change to yield X amount of power increase?

 

The general rule of thumb I've always used is 10 deg. F drop in charge temperature is worth 1% in power. I'm interested to see if anyone else here has found differently.