ported head

[agthang]

What kind of gain can I expect from a head ported..
What is the range should I expect to pay

[AznVirus]

what does it mean by a ported head?

[Sleepy]

its were they regrind you valve seats and they well usally do a 3 angle cut lets exhaust escape easier

[P10DET]

Originally posted by agthang
What kind of gain can I expect from a head ported..
What is the range should I expect to pay

I think you can expect maybe 10 hp or so in a ported SR20 head. There is not a lot of hp to be picked up there. It's really one of those mods for when you've exhausted all the better bang for the buck mods.

I would expect to pay between $600 and "how much money do you have?" My DPR Stage VI head was $2,000, but that included a couple of extras. I think JWT will do a head for $900. I know Mike Smith does great work for them.

Heads are funny things..... They are much easier to screw up than to make better.

As for those asking what head porting is......

It can mean several things depending upon how much money you have. Porting itself is merely smoothing out the rough surfaces from casting the head. It is usually accompanied by enlarging and reshaping the ports for better flow. The danger is increasing the flow ability too much and also screwing with the swirl and tumble of the air flow into the cylinder. These things all affect the hp you will gain. Also, larger ports will need lots of air flow to make power, meaning high rpm. Really good head porters can get good hp w/o hogging out the ports.

I believe Mike Kojima covered this subject in his "Suck, Squish, Bang, Blow" series in SCC.

[P10DET]

Originally posted by G20-KIWI
I have thought about getting the head on my G20 ported but I was saving for an aftermarket computer as I was told that the factory ROM wouldn't handle the changes, anyone know if this
is true?

The factory ECU cannot be reprogrammed. However, Jim Wolf Technology can do so by unsoldering the factory chip and installing a new one that is replaceable. Unfortunately they do not sell in NZ. However Glen "Lumpy" Campbell in OZ can get them for you.

[P11GT]

from what info ive gathered by asking around, porting the head apparently wouldnt gain that much, well not for the ammount of money you'll part with. Basically, the head is already well designed so porting wouldnt make a great difference. However, have you thought of fitting Twin Weber Carbs?

[P10DET]

Originally posted by P11GT
from what info ive gathered by asking around, porting the head apparently wouldnt gain that much, well not for the ammount of money you'll part with. Basically, the head is already well designed so porting wouldnt make a great difference. However, have you thought of fitting Twin Weber Carbs?

ACK!!!! :apuke:

A short runner intake manifold would be a better idea. The GTi-R manifold is nice, but it's not a direct bolt-on for the DE. The ports are shaped differently and there are other issues as well. Quite a custom installation.

The other solution would be quad throttle body fuel injection. We have a few solutions here in The States, but no manifolds, so they would have to be custom made.

The short runner intake manifold is the best idea. There is a gentleman here in The States offering them for around $500 and $800 plus core. Also a lot of money for the horsepower gained. Again, it's one of those things for when you have done all the other mods with better cost/dollar.

[P11GT]

i know that there is a 'short' intake manifold for the P10 but not sure about the P11, for the weber carbs or 'quad throttle bodies'
the P11 inlet is at a different angle to the P10, one of them is at a 45 degree angle, cant remember which one.

[P10DET]

Originally posted by P11GT
i know that there is a 'short' intake manifold for the P10 but not sure about the P11, for the weber carbs or 'quad throttle bodies'
the P11 inlet is at a different angle to the P10, one of them is at a 45 degree angle, cant remember which one.

Ah, I didn't realise the P11 came with the low port engine in the rest of the world. I thought that engine was a North American market thing.

None the less, it would still be possible to have someone modify a stock manifold the sam way. Just cut the runners and weld on a plenum. If you really want to do it right, yoiu have a flange made for the ACC valve and weld it on the end of the plenum.

The advantage of the short runner manifold is that you retain the precise control of the EFI. The only reason the Webbers or Mikunnis make a bunch of power is the short runners. So, if you still want to go that route, a quad TB injection set-up would still be a better solution. You would have to get the stand-alone ECU set-up and learn to program it though.

[agthang]

Thanks for the information.. I will continue along the path of bolt on. maybe headers,ecu next

[G20-KIWI]

Carbs? No way! Quad throttle bodies all the way!
If you wanted to a port/polish you may as well save and go the whole
way and do the cams as well especially if you are paying for the labour.
I believe from my experiences exhaust/headers and a good airfilter
are the best ways to start then you get tricky.

If you have the money you can order quad throttle bodies and all sorts
of cool stuff from Japan like Trust, that just bolt on with minimal fuss.

[P11GT]

do you guys actually know what Twin Weber Carbs are?????? they are 'quad throttle bodies'

DOH!

[P10DET]

Originally posted by P11GT
do you guys actually know what Twin Weber Carbs are?????? they are 'quad throttle bodies'

DOH!

Yes we do. They are carbs. We are talking about EFI quad TBs. Quad TB EFI will be significantly better than a set of Webber 40 DCOEs or 45 DCOEs, or even Mikunis (which are less tempermental).

[P11GT]

OK, didnt mean anything by it, it just that where im from, people generalise them by calling them Twin Webers, for short. It covers a whole range of throttle bodies.

[G20-KIWI]

Webers waste petrol they pour it in. Why dont you just take a step
backwards in technology!.:silly2:

They have their applications but I dont think you could run carbs
anyway cos you could not set up the computer to run. Hey why not
just put a blower on it.