ITB heat insulators?

[Nux]

I'm in the middle of a top-end rebuild on my 3.2SS with EFI/ITB.

Wondering a little about insulators for my ITB's. Are these required - and for what reason?

My ITB kit is from Closed Course Motorsport and actually has an extended flange for the CIS injector cutout on the cylinders:




So should I get insulators anyway to disspate the heat? Or is it not necessary?

[914efi]

I would use them. They don't dissipate heat, they reduce heating of the intake by the heads.

Is it just the photo or is the bore of the manifold very rough? Also the sealing surface looks not very smooth, vacuum leaks will be trouble if this does not seal well.

[Nux]

alright. I'll order them. It's just because.....the more I read about 911 engines, the more I find a lot of pseudo science out there. Not a lot of evidence. Do the insulators make a difference?

The bore is a bit rough - not too bad though. The sealing surface is actually very smooth, those are tiny scratches. I may give it a fine sanding before install.

[914efi]

You are right about the 'fake' science being everywhere. You need to read between the lines in many cases.

I doubt it makes a real world difference but it is a step in the right direction to have heat isolation. You don't want to cool your engine through your intake system!

Heating of the intake charge is to be avoided, but it is an incremental type of issue for normal duty. In the old days it mattered more when you had fuel in float bowls close by. In this case the fuel is up higher and under pressure so low chance of old-school vapor lock. Having said all that, I would still use the isolators...

[jpnovak]

There are phenolic insulators exactly for this purpose. They were originally designed for carbs where latent heat from the engine would cause the fuel to boil in the float bowls after shutdown. The insulators slow down the heat transfer and do work.

This is not as much of an issue for EFI systems. However, the location of your MAT/IAT sensor must be in a place that lessens heat soak. Otherwise, you have to tune around it with your temperature compensation curves.

[Nux]

My MAT sensor is located on top of one of the velocity stacks - which should be the correct intake temperature.

[75 911s]

Anyone have a recommendation for brand or type of phenolic insulators?

[Nux]

Complete kit here:

Heat Insulators

[75 911s]

Thanks for the link Nux, but there's a leak warning regarding the CIS injector cutouts in the head. Wasn't your 3.0 originally a CIS car? What about the Porsche intake manifold flange
Part #: 930-110-459-00-OEM

[Nux]

Originally Posted by 75 911s

Thanks for the link Nux, but there's a leak warning regarding the CIS injector cutouts in the head. Wasn't your 3.0 originally a CIS car? What about the Porsche intake manifold flange
Part #: 930-110-459-00-OEM

Thank you, I haven't consideret those. They do look more appropriate

The leak warning is the reason why I was thinking about not using any insulators. My manifold has the same extended flange as PMO and should cover the CIS cutout.

[jpgroth]

What insulators did you end up using? I'm tearing apart the CIS on my 3.0, with injector notches, as we speak for CCMs Triumph kit.

[shamrok]

The CCM manifolds don't have the CIS cutout (eg. they mimic PMO manifolds), so you can use the insulators these guys sell for PMOs. Heat Insulators

[trond]

The Oil Analysis Company (link above) flat out refused to sell insulators to me whan I admitted to having CIS heads because of the risk of having a leak. After a number of mails where I tried to persuade them to sell to me they refunded my payment

[shamrok]

When was that? I bought some in March ‘19 without much fuss. I can forward my email traffic back and forth to them, as they wanted some details.

[jpgroth]

Originally Posted by trond

The Oil Analysis Company (link above) flat out refused to sell insulators to me whan I admitted to having CIS heads because of the risk of having a leak. After a number of mails where I tried to persuade them to sell to me they refunded my payment

Similar experience here. They don't seem like they are going to budge on their decision.

[pampadori]

I purchased part number 901.108.131.10 from the only website that carries them when you google the part number. Sorry, its against rules to post links to competitors site so you got google it.
THey aren't cheap though. I spent almost as much on these s i did one rack of Triumph T595 ITBs! (that's too much of an exaggeration because i bought my ITBs for $125 on ebay.)

The temp differential between the manifolds and the heads is remarkable even 10 or 15 minutes after shutting the engine off.
Run gaskets on both sides of course.

[trond]

what I don't completely get is WHY use an insulator at all. These are not carburettors. I am currently running EFI injectors in the original CIS runners and they are closer to the heads and they seem to have no issues with temperature that I can tell. I'll go without

[betterair]

Did you check w PMS-Phoenix for insulators?