Would a phenolic spacer be of any benefit?

[turbovanman²]

I know the exhaust is on the other side so would using one on our intakes actually be a benefit or a waste of time and money?

[johnl]

Phenolic is a great heat insulator; it is also ablative; that is it won't burn, even under a torch. As such, when placed between the head and a manifold, it will slow the transfer of heat from the head to the IM. I've seen a 100* difference in the exterior temperature above and below my phenolic spacer. It is sandwiched between the upper and lower halves of my 2 piece.

[Anonymous_User]

I know the exhaust is on the other side so would using one on our intakes actually be a benefit or a waste of time and money?

Even though your intake mani isn't sitting right over the coals, I think it would help. Phenolics are commonly used on V8's also where the intake is not cooking over the exhaust.

[turbovanman²]

Phenolic is a great heat insulator; it is also ablative; that is it won't burn, even under a torch. As such, when placed between the head and a manifold, it will slow the transfer of heat from the head to the IM. I've seen a 100* difference in the exterior temperature above and below my phenolic spacer. It is sandwiched between the upper and lower halves of my 2 piece.

Yes, but your intake is right over the exhaust manifold.

Might still be something to consider and if I did, what thickness to get? Looks like 1/2 to 3/4" would fit in there.

[mario03SRT]

I had one on my SRT and they work Great! The intake mani was only hot after a good heatsoak at a stop light etc. Cool Air = denser air = less timing retard = HP

[contraption22]

Seeing as that you can barely fit your hand between the intake runners and the biggest source of heat in the engine compartment, I am sure it would keep the upper half and the coolant temp sensor cooler, but would it really make a difference in the temperature of the air entering the combustion chamber?

[johnl]

Mike -

I have an asbestos/foil heat blanket that wriggles between the bottom of the IM and the EM.

As for thickness of the phenolic, I placed a lightly crushed ball of aluminum foil on top of the T2 intake plenum and closed the L body hood on it to determine the headspace clearance between the two. Measured the flattend ball and found that I had about a 1/2", so I decided that 3/8" was as thick as I could go with the phenolic spacer. 3/8" works, no contact.

Do NOT breath the dust when you machine phenolic. Dispose of your chips right away. It chews up tools too.

[GLHNSLHT2]

Do NOT breath the dust when you machine phenolic.

oops

[turbovanman²]

Mike -

I have an asbestos/foil heat blanket that wriggles between the bottom of the IM and the EM.

As for thickness of the phenolic, I placed a lightly crushed ball of aluminum foil on top of the T2 intake plenum and closed the L body hood on it to determine the headspace clearance between the two. Measured the flattend ball and found that I had about a 1/2", so I decided that 3/8" was as thick as I could go with the phenolic spacer. 3/8" works, no contact.

Do NOT breath the dust when you machine phenolic. Dispose of your chips right away. It chews up tools too.

So go at least 3/8 inch or does it really matter? I would think a 1/4 inch would be easier to work with.

oops

THAT explains everything,

[johnl]

I went with 3/8" because the thicker the better and because that's all the room that an L body allows. Thicker also gives more distance to straighten/blend the turn at the part/joint of the 2 piece IM. I also like the idea of giving the IM a touch more internal volume while that 3/8" or 1/2" of extra length may add some inertia to the charge that might offset the presumtive reduction in charge velocity that goes with porting to a larger average diameter.

[turbovanman²]

I'll go 1/2" then, I don't have much more room.

[badandy]

I just caught this thread albeit late (like normal for me I guess).

With a stock plenum 2 piece plenum I don't know how much of a benefit a phenolic spacer would be due to the lack of plenum volume. I wouldn't think the air would stagnate long enough to be succeptible to convection...I do agree that every little bit helps though...it definately can't hurt! My concern with a stock 2 piece plenum would be that you are effectively increasing the runner length by adding a spacer...adding even more torque.

With a large plenum intake I believe a phenolic spacer is mandatory for the 8v cars. The larger the plenum the longer the air stays in the plenum which would make it more succeptible to convection.

...of course this is all theory and testing it tells the tale

[turbovanman²]

I just caught this thread albeit late (like normal for me I guess).

With a stock plenum 2 piece plenum I don't know how much of a benefit a phenolic spacer would be due to the lack of plenum volume. I wouldn't think the air would stagnate long enough to be succeptible to convection...I do agree that every little bit helps though...it definately can't hurt! My concern with a stock 2 piece plenum would be that you are effectively increasing the runner length by adding a spacer...adding even more torque.

With a large plenum intake I believe a phenolic spacer is mandatory for the 8v cars. The larger the plenum the longer the air stays in the plenum which would make it more succeptible to convection.

...of course this is all theory and testing it tells the tale

Ahem, this is in the TIII section, so no plenum,

[badandy]

Ahem, this is in the TIII section, so no plenum,

Grrrr...

Simon, I know that But when reading through the posts 8v was previously mentioned...that is whay I clarified with "8v"...and a 16v still has a plenum...just not a seperated plenum.

[turbovanman²]

Grrrr...

Simon, I know that But when reading through the posts 8v was previously mentioned...that is whay I clarified with "8v"...and a 16v still has a plenum...just not a seperated plenum.

Hahhhaha, true to a point, but you can't seperate the plenum, as you know,

[badandy]

Hahhhaha, true to a point, but you can't seperate the plenum, as you know,

Yes sir...but I'm not a cool kid like you 16v guys

My point was more that with added plenum volume *I believe* that a phenolic spacer comes more into play...granted this didn;t really pertain to you or most 16v guys...but still good for discussion.

[turbovanman²]

Yes sir...but I'm not a cool kid like you 16v guys

My point was more that with added plenum volume *I believe* that a phenolic spacer comes more into play...granted this didn;t really pertain to you or most 16v guys...but still good for discussion.

Who are you calling a kid????? lol!

Agreed, discussion is always a good thing,

[johnl]

Oh phooey on the TIII objection. I still love ya Simon. Thanks for the wheels BTW.

Andy, a ported 2 pc, compared to a stock 2 pc, will have a bit more volume and therefore flow a bit slower in velocity and the addition of a 3/8" or 1/2" spacer likely will have the same effect; it adds a bit of volume at that larger ported diameter and therefore the port velocity at a given engine speed will be a bit slower.

That said, the whole column of air in a ported and spacered IM port will have more weight and inertia too. Harder to start flowing but also harder to stop too, so more chamber filling - assuming cam timing, etc . . . . . Nothing new, you guys know it anyway, just my 2 cents.