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porting question

1031 Views 5 Replies 5 Participants Last post by  Underw0rld
i was wondering if porting my stock 98 heads and manifolds is worth spending the money. ive been thinking about saving up some money and buying a set of good ported and polished heads. but would porting my stock heads, lower and upper manifolds and possibly my exhaust manifold be worth it? thanks and if i was how much would the porting cost or is it easy to do urself?
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First off, you can't port your intake manifold. It is plastic. You can port the upper plenum of the manifold but you will get better results if you just buy an aftermarket one. Secondly, you can port your stock heads and you will get good results by doing so. The two main restrictions on your engine, though, are your camshafts and your intake manifold. I would replace those two things before moving on to ported heads.
Monkey Boy is right.
Don't try porting the plenum, just get an aftermarket one.
The cam/valve springs make a huge difference too. As Monkey boy says, if you do some thing you definitely want to change the cams too.
Only cams, or only heads won't help a lot.
If you want to go thru all the hassle of porting heads, you want to do the following things too:

- Larger throttle body
- Aftermarket plennum
- Port the heads (or go with ported PI heads / intake)
- Get good cams/springs
- Get long tube headers
- get a high flow exhaust.
- get a programmer and maximize output at higher RPM (advance spark)

(all those mods will make your motor become a high screaming RPM hugry beast)

Talking about the head porting:
I know that in the past some people got into a huge argument over air flow and heads (people got banned).

Since I've never ported 4.6 2V heads myself, I can't realy say a lot.
But as always, the biggest improovement in air flow is not being done by polishing the intake runners, they are already a lot larger (cross section) than the valve pocket.
Cleaning up the valve pockets is always a good idea; especially around the valve guide. The transition from the runners into the valve pocket into the valve seat is a key element too.
Looking at the combustion chamber, you definitely want to smoothen out that turbulence vane and the valve seat.

I don't know how much you like to do things like that - I love it.
If I would be you I'd just get me a set of used heads and do exactly what the guy did in the article below. +20% on the intake and +15 % on the exhaust sounds bretty darned good to me.

Have fun porting!
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i've been looking for an PI upper intake for awhile now and haven't really been able to find anything impressive. ive only been able to find stock replacements u know the ones that have the aluminum cross member instead of the plastic. my friend just installed one in his car and he said he couldn't really feel any power increases. informationg on where to find an affordable pi manifold would be great. my budget is around 250-300 dollars. and if i were to port my heads and manifolds how much would that cost?
The lower intake is the part with the aluminum crossmember. The upper portion is the piece commonly referred to as the plenum.
red98gt said:
if i were to port my heads and manifolds how much would that cost?
Heads ~1700-1800

forget about the manifold
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