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Discussion Starter #1 (Edited)
how much power gain would you have by porting intake and exhaust of head for D15B VTEC? i have done 3 degree valve cut and ported the inside the valve seats and TB and intake manifold but i have to pay some more to have my intake and exhaust also ported! does it worth it? it is going to cost me around 200 US$ to do that. it is going to be N/A and i have stock intake manifold.

how effective is that?
 

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Discussion Starter #3
you would notice more of a gain if u went turbo! sure its a good investment, if u have plans on going turbo... other then that im not too sure
so you mean for N/A it is not going to be noticeable, right?
 

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Firstly, you want to know for sure what you are aiming for. If you want to go turbo, then you ned to be looking in to getting a kit together. Have a look at some of the setups in the FI section, there are some people putting down some very nice numbers!

On the other hand, if you want to be going for a big power N/A machine, then a well worked head is key to power. Basically, an engine is all about pumping air. Sucks it in, compresses it, combined with the fuel it then combusts, and finally its pushed out. So as you can see from the real basic description, having it flow well is going to have big benefits.

To really get the benefits your going to need port matching of the intake mani and exhaust mani etc.
 

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the idea is the same, all you are doing is openin up your head to accept more airflow...which means your engine will breath easier, and it will have bigger power capabilities...and in these engines, every little bit counts, ESPECIALLY if you are staying N/A. The power difference is noticable, but not ridiculously large...this is one of those things where you are the master of your own demise...if you port/polish/shave, than to fully benefit from that you need to upgrade your ignition, fuelpressure regulater, and exhaust/intake...maybe injectors, it really depends how far you are goin with the build
 

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the idea is the same, all you are doing is openin up your head to accept more airflow...which means your engine will breath easier, and it will have bigger power capabilities...and in these engines, every little bit counts, ESPECIALLY if you are staying N/A. The power difference is noticable, but not ridiculously large...this is one of those things where you are the master of your own demise...if you port/polish/shave, than to fully benefit from that you need to upgrade your ignition, fuelpressure regulater, and exhaust/intake...maybe injectors, it really depends how far you are goin with the build
How noticable? why whould he need to upgrade his ignition?
 

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The main objective is get the air to pass around the valves, in the straightest line possible.
So the valve job is really the key... Smoothing out the casting marks could do some good, but for it to be worth the effort, do it while the head is off for something else.
I highly doubt you will notice any gains from this alone...
And if you don't know exactly what to do, I'm sure you can actually hurt flow...

Power seems to lie in the valve job and bowl shape on these engines, not port size...
Of course, if using larger valves, the port must be reshaped to match the larger diameter of the valve.
 

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Discussion Starter #12
The main objective is get the air to pass around the valves, in the straightest line possible.
So the valve job is really the key... Smoothing out the casting marks could do some good, but for it to be worth the effort, do it while the head is off for something else.
I highly doubt you will notice any gains from this alone...
And if you don't know exactly what to do, I'm sure you can actually hurt flow...

Power seems to lie in the valve job and bowl shape on these engines, not port size...
Of course, if using larger valves, the port must be reshaped to match the larger diameter of the valve.
OK, to make things clear for my case, these are what have been done on my engine till now.

1. bore the cylinder 0.5 mm and bought over sized pistons.
2. 3 angle valve seat cut
3. port the valve bowl
4. port the TB and put bigger valve
5. port the entrance of intake manifold
6. shave the head
7 deck the block

is it gonna worth it to pay some more and port the head also? i have actually spend over my budget for those and parts and i want to do this only if it is necessary for gaining more N/A power. i just don't want to make all my efforts and money useless because i didn't do a port job and also don't wanna pay some more to get something which is not going to have a great impact for my case.

i will post some photos tomorrow.
 

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No, it's not at all necessery... I'd rather use the money on a more agressive cam.
In fact, seems you have already ported your head as far as valuable work goes.
Don't worry about doing any more atleast. That is my humble opinion.
 

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Are you kiding me? :fag:
Do you honestly know what you are talking about?

Let me give you a hint, I have done a valve job/work with a set of brodixs for a 528 cubic inch BBF with twin 91s. The motor makes ? rwhp (peaks dyno) and has run a 6.66 @ 215.

The heads used to be on a 604 inch pro 5.0 with a fogger.

So do you mean to tell me that these heads shouldn't have worked because the turbo has different requirements? Give me a break . . .

In a boosted application, quantity > quality. Viol8er was exactly the opposite of what you want to do.

Not that any of you know or care, but thats why Big Chief heads work so well when you are blowing 30lbs from a 14-71 and suck on the motor. The ports are piss poor but are freaking huge.
 

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Do you honestly know what you are talking about?

Let me give you a hint, I have done a valve job/work with a set of brodixs for a 528 cubic inch BBF with twin 91s. The motor makes ? rwhp (peaks dyno) and has run a 6.66 @ 215.

The heads used to be on a 604 inch pro 5.0 with a fogger.

So do you mean to tell me that these heads shouldn't have worked because the turbo has different requirements? Give me a break . . .

In a boosted application, quantity > quality. Viol8er was exactly the opposite of what you want to do.

Not that any of you know or care, but thats why Big Chief heads work so well when you are blowing 30lbs from a 14-71 and suck on the motor. The ports are piss poor but are freaking huge.
see now i've read diffrent views on this subject on this site. who's right who's wrong. i'm still researching this cause i want port work done and i want it done right the first time. i will spend what it takes to get my desired result. i wrote what i believed to be close to fact. not saying your right or wrong. i usally believe someone who has done it and is putting up numbers to back up their claim.
 

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OK, to make things clear for my case, these are what have been done on my engine till now.

1. bore the cylinder 0.5 mm and bought over sized pistons.
2. 3 angle valve seat cut
3. port the valve bowl
4. port the TB and put bigger valve
5. port the entrance of intake manifold
6. shave the head
7 deck the block

is it gonna worth it to pay some more and port the head also? i have actually spend over my budget for those and parts and i want to do this only if it is necessary for gaining more N/A power. i just don't want to make all my efforts and money useless because i didn't do a port job and also don't wanna pay some more to get something which is not going to have a great impact for my case.

i will post some photos tomorrow.
What compression pistons are you running? If you’re running high compression pistons get the head ported if not don't bother. IMO
 

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see now i've read diffrent views on this subject on this site. who's right who's wrong. i'm still researching this cause i want port work done and i want it done right the first time. i will spend what it takes to get my desired result. i wrote what i believed to be close to fact. not saying your right or wrong. i usally believe someone who has done it and is putting up numbers to back up their claim.
In supercharged/turbo applications, a larger port volume (CC) will 9 times out of 10 make more power than one with less. Drawing in air has a lot more to do with proper size and shape than blowing it in.
 

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Discussion Starter #18
What compression pistons are you running? If you’re running high compression pistons get the head ported if not don't bother. IMO
it s Honda stock D15B VTEC 0.5mm over sized pistons. i am not sure about high compression or not!
 

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He already has valve job and bowl shaping... That's the most important parts of a "port" job.
The only thing left to do is shaping the ports themselves, and I really think there's little to gain for you there.
Spend money otherwise, on a cam and some tuning. Then you should get some nice gains from the increased amount of air flowing through it.
 
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