Top end overhaul

[911/914gary]

I'm having a top end overhaul on my 3.2. My wrench recommended that I have my heads ported and polished plus have the intake manifold micro polished. Based on the cost estimate this is a highly labor-intensive modification. He says this will significantly increase in airflow. However I do not know what performance gain I can expect from this. There might be other cost affective modifications I may want to consider instead. Does anyone have any experience or feedback to this modification?

Also, beside the typical top end work what other modifications would be recommended?

Thanks...Gary

[GIBSON]

I'm interested in other peoples opinion on this as well- I've always thought that porting and polishing a stock engine, with no other modifications planned, was of minimal value- speaking here of 911 engines. The 911 head flows pretty well stock, as opposed to other heads with heavily shrouded valves etc.
Unless you are planning on some modifications that will increase the need for more flow or be able to benefit from increased flow (larger valves, bigger cam, different intake system) then a simple increase in air flow potential will offer little in terms of horsepower gains and probably not be worth the bucks spent.

Real improvement for 3.2 engines usually comes in the form of increased displacement, cams and possibly different engine management. IMHO...

[jabb]

I would pass on the porting on a stock motor.....
while its a part you might wnat to change the grind on the cams
Less money more bang for the $$$..............

[Superman]

I upgraded my cams and I LOVE them. Next, I will backdate the exhaust, which should make the car even more fun.

There are certainly instances where polishing an intake DECREASES performance. So, polishing 911 heads and intakes is of questionable value, unless you know what you're doing.

[911/914gary]

My wrench is pretty competent with these types of modifications. I've seen examples of manifolds that were "extrude-honed" out of his shop and they are impressive looking. However what I am hearing so far is this will probably not benefit me much without other modifications. Based on a letter I read in Excellence Tech Notes II, there was a significant power gain after adding a polished manifold. However the baseline engine was a twin plug 3.5L with a modified cam.

So, now I am considering polishing the manifolds myself. I know I can't achieve the finish the extrude-hone process yields (a 32 or better surface finish). But I should get a better than factory finish. This way I can afford to add a sport ground cam.