There are plenty of guys here that will disagree with me, but...
I worry about the thermal expansion characteristics of the phenolic being different than those of the aluminum intake.
This could result in excessive stress on the 'tabs' at the front and rear of the upper intake.
I had a cobra intake years ago which I used with a phenolic spacer. One day when un bolting the manifold, the front tab broke off.
I can't say for sure if it was the result of the phenolic spacer, but it is a possibility.
Again, I am sure several guys will post that they didn't have any issues when using a phenolic spacer.
Not sure how much power the spacer will gain, but it should gain a little
I worry about the thermal expansion characteristics of the phenolic being different than those of the aluminum intake.
This could result in excessive stress on the 'tabs' at the front and rear of the upper intake.
I had a cobra intake years ago which I used with a phenolic spacer. One day when un bolting the manifold, the front tab broke off.
I can't say for sure if it was the result of the phenolic spacer, but it is a possibility.
Again, I am sure several guys will post that they didn't have any issues when using a phenolic spacer.
Not sure how much power the spacer will gain, but it should gain a little
vristang, I never though about that but have a few friends, 2 or 3 actually who have run the spacers and cracked the tabs off as you described. I never thought that could have something to do with it, but it makes sense. The only reason i really see to run one is if you have tall valve covers or want a reason to run a bigger hood.
Upper will be cooler as a result of using a spacer. Also, the extra 3/8" or 1/2" will aid torque due to a longer intake runner. This is what I understand. You can search for before/after results on an install, for the gains. It all adds up.
I have one on my factory intake w/no broken tab issues. If you remove/reinstall upper, make sure you don't over-torque bolts. Not saying this is definately why tabs break, but you've got to be cautious about this. Aluminum is pretty soft and doesn't take much to crack or split it.
Anyway, the intake can further be cooled by not using the coolant lines routing to the egr spacer.
Mike
I have one on my factory intake w/no broken tab issues. If you remove/reinstall upper, make sure you don't over-torque bolts. Not saying this is definately why tabs break, but you've got to be cautious about this. Aluminum is pretty soft and doesn't take much to crack or split it.
Anyway, the intake can further be cooled by not using the coolant lines routing to the egr spacer.
Mike
Only if you also block off the egr passages at the lower intake or the head.
Also the longer runner brings the powerband lower in the rpms. You get more power down low, less power up top. It's a tradeoff but it can help heavier cars get going a little quicker, they'll be slower on the big end though.
Beat me to it. As long as you are still running an EGR system you are passing hot exhaust gasses through the upper. So I don't think that the spacer will help cool it that much.
That said I run a 1" spacer on my car but only to clear my tall VCs