Phenolic Spacer

[Strat-Supra]

Granted, they're not expensive but some manifolds need slight modifications when using a spacer, which makes me think some vendors didn't design their manifolds to accommodate a spacer. For example, I've only been able to find a single thread where someone (BMW forum) used a spacer with the Wagner Tuning B58 manifold, but it required modifying the manifold to clear the cylinder head.

https://g20.bimmerpost.com/forums/showthread.php?t=2055931

I've also read that the decrease in temperature of the manifold is not significant enough to affect the air temperature due to the velocity of air moving through the intake. Then I've read they're a must with an aftermarket manifold.

Are phenolic spacers worth it?

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[TBK]

I guess it depends on your use case. If you have an aftermarket manifold (aluminum, great conducor), it does turn into a bit of a heatsink because it's going to absorb heat from the engine head.

In the real world though whether a spacer helps i think comes down to what you would want it for. We have a water-to-air intercooler integrated into the manifold, so heat soak for us is a bit complex. And a spacer is a lot more useful when you're stationary (no airflow to help) vs when you're in motion (airflow does the majority of the heavy lifting), so i'm not sure how useful it would be if you're looking to reduce IATs at the track (not the drag strip). Basically the spacer helps with conduction, but doesn't do anything against convection.

Similar logic i guess why i don't really see much value in having a bigger fan, unless you wanted the fan for in-between sessions. But there are knowledgeable folks here who disagreed with me on that.

i would like to learn more about this in general

 

[Strat-Supra]

Thanks for replying.

I get the heat soak when stationary, but once moving the increase in temp should come down quickly. Yes, aluminum is a great conductor but it's also good at shedding heat in most cases and these manifolds aren't thick blocks.

Yea, the intercooler in the manifold does complicate things a bit. Though I can't imagine the intercooler is heating up at the same rate the manifold would. This is conjecture on my part as I've not seen inside one and how the intercooler is attached to the manifold.

Hopefully others will chime in with their knowledge and experience.

 

[razorlab]

Thanks for replying.

I get the heat soak when stationary, but once moving the increase in temp should come down quickly. Yes, aluminum is a great conductor but it's also good at shedding heat in most cases and these manifolds aren't thick blocks.

Yea, the intercooler in the manifold does complicate things a bit. Though I can't imagine the intercooler is heating up at the same rate the manifold would. This is conjecture on my part as I've not seen inside one and how the intercooler is attached to the manifold.

Hopefully others will chime in with their knowledge and experience.

With the aftermarket manifolds, the intercooler is literally the whole middle bit. The plenum and the ports are welded to each side. The boost/temp sensor is on the port side, and goes into one single port. (I circled it in the 3rd and 4th photos below)

These posts by do88 show it well:

 

[Z4m40i]

Running a BMS spacer with the Wagner. I probably did about 6-7 track days prior to the spacer.

Whether it made a difference was pretty difficult to tell. Placing my hand on top of the intercooler after runs felt cooler, but IAT’s didn’t seem to improve.

I had to make small notches in the intake runner to clear the head, increase the fastener lengths, new charge pipe, and add several washers to the brackets to mate it to a slightly raised manifold.

I’d imagine it’s something like canards- not really that good by itself but has more function when paired with something else (like hood vents)

 

[Strat-Supra]

With the aftermarket manifolds, the intercooler is literally the whole middle bit. The plenum and the ports are welded to each side. The boost/temp sensor is on the port side, and goes into one single port. (I circled it in the 3rd and 4th photos below)

These posts by do88 show it well:

Thank you for sharing this.

Assuming the pic of the Wagner installed is yours, I'm not seeing marks from filing to clear the cylinder head. Am I correct in saying you're not running a spacer?

 

[razorlab]

Thank you for sharing this.

Assuming the pic of the Wagner installed is yours, I'm not seeing marks from filing to clear the cylinder head. Am I correct in saying you're not running a spacer?

Correct, no spacer. I have had issues with them in the past so decided not this time around. Been working out just fine for a couple years now. 600whp+ and 20+ track days a year.

 

[Rizen]

This seems like the type of modification that you'd do when you have already done everything else, given it's not so simple to make work on this platform. I had phenolic spacers on my Subaru, but all that required was some longer bolts for the TGVs. Everything else more or less lined up.

There's a lot of other cooling mods you can do.

 

[Subydude]

Given the air going through the intake manifold is usually moving over 100 mph when you're out on track, the phenolic spacer isn't going to do much. In stop and go traffic where the air is much slower moving through the IM and has more time to leach the heat from the housing it can help. By nature the airflow through the IM will cool it off, and the spacer will help mitigate heat from the head being transferred over. How much heat transfer/cooling varies a lot by use case.

Like most small cooling mods it's generally not worth it on it's own, but if you're chasing that last little bit of heat management AND already have it, it definitely doesn't hurt.

 

[Strat-Supra]

Thanks all, appreciate the replies, they've been helpful.

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