This is a bit longwinded, but as it's about relatively cheap power gains I know you'll be interested :D .

We all know that the colder and therefore denser the air is entering your engine, the better. That's why many of you have or want aftermarket CAI's right?

About a year ago I read an article that gave an actual figure for the power increase you could expect for every degree reduction in induction air temperature. I could never find the article again but recently found on the RPW website something that stated that "a 5 degree Farenheit (approx 2.7C) reduction in air temp equates to a 1% increase in power. This isn't RPW's quote, but one of their suppliers. It also may be a complete crock, but lets assume for the moment that it's right.

RPW now sell a widget called a "manifold insulator block" which is basically a 5mm thick gasket which fits between the upper and lower inlet manifold. The gasket has a very low thermal conduction index and reduces the heat transfer from the engine to the inlet manifold. In theory it sounded good so I bought one ($200).

2.5 hours after receiving it in the mail I had it installed. I took the car out for a bit of a fang, lifted the hood placed my hand on the manifold and it was warm but didn't burn. I put my finger on the lower manifold. It did burn. Quite a lot actually :redface:

If you drive fairly hard for half an hour or so, the manifold still gets uncomfortably hot to touch but it's still heaps cooler than the lower manifold and engine so the insulator block really does it's job well.

I've always thought my car develops more power when the engine is cold and the effect of fitting the insulator block is similar to this except of course with the insulator block the engine warms up and can be revved while the manifold stays relatively cool. The improvement isn't dramatic but it is noticeable and would work really well with other induction mods I reckon.

I'll take some temp readings soon of the upper and lower manifolds and let you all know what the difference is.



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Thanks for the info... I've been wondering if this thing was a gimmick or not!

Cheers,

Thanks for the info... I've been wondering if this thing was a gimmick or not!

Cheers,


Yeah, I thought the same thing but in theory it makes sense so I thought I'd give it a go.


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Has anyone looked into seeing if anyone out there has made or has sources of an after market plenum for the magnas???????
Talked to a guy who has done some work on my car nad he says that a guy who works at Cyber is looking at doing such mods to cars and hasn't thought about magna's yet. I told him to drop him a suggestion to see what he would think, and even if he wanted to use my car ( yeah i wish ) as the trial job. If it comes through i'll let you know but if anyone out there knows someone who can do this then let us know!! :badgrin:

Hey really have you thought about getting the aftermarket cold air job, or even making your own ( bit of stainless piping and some silicon colour coded piping ) and placing the filter in the front bumper. Oops you would have to place a pod on. And yes i know what they say about pods being so low and getting water in there. But you can get water proof covers and it's easy dont take it through flood ravaged crossing's

instead of $200, I cut a piece of Silcon rubber I bought from Clark Rubber into shape for the gasket and I sandwiched the silcon with the metal gasket and it worked as well.

instead of $200, I cut a piece of Silcon rubber I bought from Clark Rubber into shape for the gasket and I sandwiched the silcon with the metal gasket and it worked as well.

Does the silicon, being soft, compress though when you torque down the bolts?

The insulator block from RPW is about 5mm thick, very hard and supposedly has a very low conductive index. I'm not sure how efficient an insulator silicon is. It's a good idea though if it works. Certainly a lot cheaper lol

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Just so that you guys know these manifold insulators have been around for years the first ones that I heard of were made for the mazda 2.5 V6.

Cheers
Paul

I'm not very nockwlegeable on these matter's but I got a theory worth looking at! wouldnt stopping heat transfer across this manifold be a bad thing?? more heat would be retained in the lower section as you said, less in the upper. when things heat up they actually expand microscopically if they do not expand evenly they can crack??

please note that I know nothing about actaul engines so if this doesnt make sense in this case please ignore it!

I'm not very nockwlegeable on these matter's but I got a theory worth looking at! wouldnt stopping heat transfer across this manifold be a bad thing?? more heat would be retained in the lower section as you said, less in the upper. when things heat up they actually expand microscopically if they do not expand evenly they can crack??

please note that I know nothing about actaul engines so if this doesnt make sense in this case please ignore it!

I see where you are commong from. Since the top and bottom parts of the intake manifold are held together by bolts, having the bottom expand more (due to more heat) than the top it could put more strain on the bolts themselves leading to brakage?

Hey guys,

This is really old and well understood technology.
The insulating spacers go waaay back to carburettor days, where they work even better. Not only do they keep the carburettor cooler, but also the fuel, so you get a lot of help.
That 1% horsepower increase for every 5 degree farenheit is absolutely correct. Doesn't sound like a big deal, but when you consider(please consider?) that under bonnet temps can easily reach 140f, and outside is pushing s**t uphill to be 100f....well, there's 8% improvement!
I have a foot in both camps, have a fuel injected car and carburetted, and they both benefit from cold air and ram air. My old Valiant has cold/ram air and I have measured a consistend 25 degrees cecius difference in engine bay temps and the cold air from the ducting.
On the girlfriend's 2.6 TS, I removed the very restrictive snorkel off the air filter box(and those plenum silencer boxes), and put a divider from the front of the air filter box to the battery box. So, now the engine gets cold air from in front of the radiator support through the factory stamped holes that are there, and also receives a slight ram air effect due to the air being slightly pressurised. The radiator support is a great place to pick up ram air.
Ram air is also good for power. A Maclaren Indycar in testing at Indianapolis picked up 1.5 seconds a lap with just a ram air scoop.
The beauty of fuel injected cars is they measure both the airflow and air temperature, and just compare it to teh tables the computer has stored in them, and adjusts the mixture accordingly. With carbs, you have to rejet etc.

Regards, Andrew.

I'm not very nockwlegeable on these matter's but I got a theory worth looking at! wouldnt stopping heat transfer across this manifold be a bad thing?? more heat would be retained in the lower section as you said, less in the upper. when things heat up they actually expand microscopically if they do not expand evenly they can crack??

please note that I know nothing about actaul engines so if this doesnt make sense in this case please ignore it!

This crossed my mind too. If it were a problem for the manifold it would be just as big a problem for alloy heads sitting on cast iron blocks as the rates of expansion for these two metals is different. As far as I know it's not a problem.


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