How Much Gain Will I Get From This?

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chad123

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anyone know about how much more horse power i will get from swaping my hf (d15b6) head intake manifold and ecu,tranny ,to a si head ,intake manifold , ecu,tranny?? and does anyone know if will have any problems with this swap ??? thanks!!!
 
im talking about the 88-91 si head !!! do you know if i would have any problems with this swap and yeah i have 2nd generation crx..thanks
 
well there is a couple ways of going about the wiring of vtec. Basically you can use a msd or summet racing RMP Activation switch (sense vtec is engaged by a positive current going to the sylenoid). Or you can get the 92-95 si/ex ecu and completely rewire. OR you can hook vtec up to a toggle switch on your dash.Thats how i have it cuase i was beeing cheap but i personally enjoy it like that. Becuase then i can choose when to use it. On all these options you can use the 88-91 pm6 si ecu. And you should not have any problems doing this head swap. On my 90 si block i had to pull a little oil jet thing out to allow more oil flow to the vtec head. I am not sure about your block tho.
 
If you use the 92-95 ex/si head (d16z6)then you will have to make custom holes on your 4g distributer. But you could allso use the 96-98 civic ex head (d16y8) and your 88-91 si distributer will bolt rite onto it. the d16y8 will also offer a very slight power increase over the d16z6 head.
Use the 92 si head gasket if you are going to throw on a d16z6 head.
You have to use a 92 si timing belt also.
 
The HF pistons won't work unless you have them fly cut for the valve releifs. I've heard they only allow for the stock HF 8 valve head.
 
no this was disputed, and it was decided that the 8 valve hf's shipped with valve reliefs for a 16 valve head.
 
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