Intakes, how much to open or not?
08-05-2002, 05:13 AM
#1
Race Car
Thread Starter
Intakes, how much to open or not?
Hi guys,
I plan to open up my intake ports on cylinder head. Stock is 32mm. Apparently some of you guys go upto 38mm. However it does increase horsepower numbers but what my mechanic told me is that it will create more lag and the best is to just have it polished, which I already did my last rebuilt. According to Bruce Anderson, he advises not to go more than 36mm. What do you guys suggest from your personal experiences? Do I also have to open up my manifold to match the cylinder intakes? I guess those who have done this modification should be able to answer this best. Thanks.
I plan to open up my intake ports on cylinder head. Stock is 32mm. Apparently some of you guys go upto 38mm. However it does increase horsepower numbers but what my mechanic told me is that it will create more lag and the best is to just have it polished, which I already did my last rebuilt. According to Bruce Anderson, he advises not to go more than 36mm. What do you guys suggest from your personal experiences? Do I also have to open up my manifold to match the cylinder intakes? I guess those who have done this modification should be able to answer this best. Thanks.
08-05-2002, 09:31 AM
#2
Nordschleife Master
It depends on what manifold you are running. You will want to match your port size with the manifold you are running. Turbo port sizes are very small compared to the N/A 3.2 heads. This helps bottom end some at the expense of top end performance. Moving to larger P&C with higher compression helps bottom end. I'd work with your engine builder who knows high performance Porsche engines to determine your goals.
08-07-2002, 12:01 AM
#3
Race Car
Thread Starter
Geoffrey,
Thanks. My mechanic is against porting it. He said polishing is fine and porting will create too much lag. On the other hand, most of you guys do the porting. I'm lost.
Thanks. My mechanic is against porting it. He said polishing is fine and porting will create too much lag. On the other hand, most of you guys do the porting. I'm lost.
08-12-2002, 04:34 AM
#4
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Sameer;
I had to replace my 993 valve guides so here is a dirrect comparison to my 930 heads that I am also working on. I have opened them up to close to 41mm. Todays thinking is larger port diameters will flow more air. Yes, you will lose the bottem end with a stock 3LDZ turbo, but changing the turbo and exhaust will more than make up for anything lost.
I had to replace my 993 valve guides so here is a dirrect comparison to my 930 heads that I am also working on. I have opened them up to close to 41mm. Todays thinking is larger port diameters will flow more air. Yes, you will lose the bottem end with a stock 3LDZ turbo, but changing the turbo and exhaust will more than make up for anything lost.
08-12-2002, 09:21 AM
#6
Nordschleife Master
Kevin,
That looks like a huge difference between the 993 head (stock I assume) and the 930 heads opened up to 41mm. Who did you have do your porting work?
That looks like a huge difference between the 993 head (stock I assume) and the 930 heads opened up to 41mm. Who did you have do your porting work?
08-12-2002, 06:19 PM
#7
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Geoffrey;
It is definately a big difference, whats shocking is when you put a stock 930 head against it. If you look at the 993TT head look at how the factory unshrouded the guide. I've been thinking about how the intake charge air would be cooling the guide if more was exposed. I've done all the work. (Too many hour to count).
It is definately a big difference, whats shocking is when you put a stock 930 head against it. If you look at the 993TT head look at how the factory unshrouded the guide. I've been thinking about how the intake charge air would be cooling the guide if more was exposed. I've done all the work. (Too many hour to count).
