V2Rocket

Wondering if anyone out there would be interested in a phenolic spacer for the intake manifold. I have been working on making one for my own car for a while and have made a good piece and have alot of material left over, and the piece I bought was a remnant!

Manifold spacers are an old trick used by muscle cars etc to get just a little bit more power and torque without changing anything else. The reason for this is the longer distance the air travels generally increases velocity in the intake which is good for torque (why the 944 manifold has such long runners) and also the fuel that is suspended in the air cools off the air somewhat and if the air has to travel a longer distance it has more time to cool.

Phenolic materials are basically very special plastics that are very good thermal insulators. The aluminum head and aluminum manifold will exchange heat at a ridiculous rate. Phenolics, as with all materials, conduct heat but at a much, much slower rate. The result of this is that after a hard drive or track run the intake is cool to the touch, close to ambient, compared to being almost as hot as the rest of the engine.

The spacer I have made and would be duplicating is one long piece made of 3/8" material. In the past people here have bought phenolic kits that used 4 individual pucks (one per runner), using a one piece design simplifies the installation. Small cutouts are made matching the pattern on the manifold for injector flow.

If there is interest in these I will make them available at $80 shipped as a DIY kit consisting of:

- Phenolic spacer
- 8x 10mm longer allen bolts
- 2x sets of Intake manifold gaskets

The installation process can't get much more straightforward: remove the intake manifold, put 4 new gaskets down, put the spacer on top, put 4 more gaskets down, and reinstall the manifold with the longer bolts.

The only note for this would be the height of the spacer will require you to remove the black plastic fuel rail cover as its internal height, added to the height of the spacer, would cause it to contact the hood. I am working on a simple solution for the early fuel rails as the mounting tabs to the cam tower are not elongated like the late rails. Late rails may have to bend the tabs slightly.


I will be posting up some hard numbers for intake air temperature comparisons pre- and post-spacer in a few days, I just need to tap my spare manifold for my temperature sensors.

Potential interest list:
CameronKame
misnblu
Rogue_Ant
ZW 944
savvas 944
Dougs951
TRP951

Reimu

Show me proof that there is a change and I'd be interested

V2Rocket

carlege

I believe this was an old trick and it worked on carb'ed engines. Not so much on Fuel Injected engines. Its a waste of money / time.

misnblu

I would almost disagree with the fact that they don't do what they're supposed to do.
I've seen these phenolic spacers used on many cars that have this issue with an aluminum intake manifold and iron block or aluminum block to keep the air temps cooler going into the engine with good results.
Mind you that the power gained would not be so much that you'd actually feel it with the butt dyno but any improvement to get cooler air into the engine would surely provide a bit more power and even better gas mileage over the factory setup.

I'll be subscribed to this thread for interest.

Reimu

Yeah, I saw that

luftpirate

I don't believe intake tract heat soak is an issue as the air is not in the runners long enough/adequate surface area for significant energy to be exchanged. I would say make a prototype and test both on a dyno after the engine has reached operating temperature. I'm a skeptic but I think if it had been an issue the Porsche engineers would have done it as they pretty much did everything possible to squeeze power out of these motors after taking into account the need for moderate reliability...

Also if IATs were an issue and they were being significantly effected by a heat soaked manifold you might not realize gains with out some tuning. So not really an option for early cars but maybe some of the turbo cars could benefit. Also keep in mind the intake runner length is tuned from the factory to match the rest of the system so lengthening runners does not necessarily mean gains.

Looking forward to seeing results, not here to hate

Rogue_Ant

I am interested...

ritzblitz

I have a kit on my car.

Went from:

After track session, pop hood, spit on intake manifold, snap crackle pop.

To:

After track session, pop hood, hold hand on intake manifold for as long as you feel like because its basically cold.

Rogue_Ant

There is definitely heat exchanged between the intake manifold and intake air...
This is more pronounced during low air-flows.
True Speed Density systems, use coolant temp as the primary table in determining intake temp during low-rpm / low-airflow situations. As air velocity increases, this effect diminishes and you start having to factor in air temperature more and more until, at some point, you can effectively ignore coolant temps.


-Rogue

V2Rocket

those runners are pretty thick material and while it probably takes a good amount of heat to warm them up once they are they could radiate alot of heat into the air inside.

think about an intercooler, under all that pressure the air isnt going to be in there long. certainly the internal design of the cooler will slow the air down a bit but even the short amount of time it is in there it can drop over 100*!

hopefully will have some temp numbers soon. and lower temperature directly means more power, although it may not be much on the NA.

misnblu

Looking forward to the results too.

ritzblitz

As long as you can offer these at a good price, it's a no brainer. Its an easy way to reduce temps under the hood.

V2Rocket

ritz can you clear some pm space

V2Rocket

the principles of air velocity/torque and fuel evaporating and atomizing are the same whether the car is fuel injected or carburetted.

if anything it might be MORE beneficial in sheer terms of heat conduction and convection when you consider that a carb'd car's manifold is still bolted straight onto the head, and that the heat would have to conduct through the manifold to get to the carb, which means that air and fuel that passes through the carb and then the manifold still feels radiant heat.

a spacer underneath the manifold isolates the entire assembly (and thereby the air/fuel mix) from radiant heat until it actually enters the head.