M42 Phenolic intake manifold spacer?

[SlickAlpinweiss]

Hi,
I would like to hear your thoughts on a phenolic spacer in order to reduce intake manifold temperatures. More specifically, there is a 5mm one on eBay available from the U.K. Comes from Young Timer Motorsports I believe.
Members have said good things when reviewing jiXer's 10mm spacer, but that one is different and likely/possibly better. They have been beneficial for F.I. applications. Would the 5mm phenolic spacer beneficial or have negative effects?- For an N/A application?
Say~ you had cams, chip, bbtb, mustang injectors, electric fan, p/s & a/c delted, etc. just the average N/A mods. Beneficial to get a phenolic spacer?: 5mm or 10mm?
Thanks in advance.

[roguetoaster]

No, it should have almost no impact on intake manifold temperatures, as close as possible to zero impact on intake air temperatires, and maybe, just maybe a very slight change in torque output at certain RPM.

Just consider the actual volume of air passing through the intake manifold, it's temperature, the temperature of engine bay air, and whether an itty bitty spacer will do much to isolate the manifold from the head, especially considering that you still have metal/metal contact at the mount points.

They were really designed for carbureted cars to prevent heat soaking the fuel bowls and creating excess vapor/vapor lock.

There is basically no cheap/free power.

[bmwman91]

Well put, roguetoaster.

The M42 is an expensive engine to get more power out of. The only "freebies" are a good chip and a lightened flywheel.

[SlickAlpinweiss]

I'm glad I had asked, you having shared your knowledge is appreciated.
Now, I would also like to ask about a big bore throttle body for the M42. What do you guys think as far as this mod? Leave it factory or is enlarging the diameter for the bigger valve helpful?

[BraveUlysses]

not really, you should take bmwman's advice and stick to a chip and flywheel

[SlickAlpinweiss]

I agree a chip and flywheel are a great help. I want to consider the small mods too. I know that the coil on plug kit along with the 4 pintle injectors have improved throttle response and has given me a very smooth idle. I have read of a couple mixed thoughts on a big bore tb, because I don't have any internal modifications done. So will boring out the tb slightly have better performance than the factory?

[roguetoaster]

If a larger throttle body would give extra power with no downsides it would probably have been done from the factory.

But I suspect that there is just no need at all for more air flow. To test that you could put a restriction in the inlet path and see if you can actually feel the difference. Or you could actually have a shop with an engine dyno remove the engine, and actually tell you what or how to possibly gain more power/if it's even possible. Moreover, this is a 1.8L engine with a twin plate TB that looks to be about 80% the size of a TB on a 8.1L big block.

Just remember, that with a N/A engine, you aren't going to pick up much, if anything from bolt ons without accompanying internal work to improve flow, combustion, evacuation & etc.

[Dj Buttchug]

Bumping this old thread to ask a specific question about these spacers. Has anyone who installed one experienced issues with injector spray. The width of the spacer moves the injectors back about a 1/2. How does this movement effect the spray pattern into the cylinder.??

[bmwman91]

Just thinking about the geometry involved, I would guess that it will result in more of the fuel landing on the lower port wall rather than the back of the intake valve. I am not sure if it would matter from a carbon buildup standpoint since the M42 doesn't really have too much of an issue with that anyway, but maybe atomization would be a little less good since the port walls are not as hot as the intake valve. My guess is that the net effect would probably be negligible in terms or change (good or bad) to performance from that effect, and assuming the spacer does what it is supposed to thermally, you'd gain a little advantage from slightly less hot air arriving at the cylinder.

[Balleristic31]

Anecdotally I ran the spacer for many years both N/A on a stock engine and on with the Turbo setup with zero negative effects on idle/power output etc. Of course I don't have any official data to back this up, though. For what it's worth, I sold the spacer when I sold off all the turbo parts. Doesn't seem necessary on an N/A build. Cheers, Ryan!