1991 Crx Hf To Si Conversion Help

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bern74

Junior Member
I need a site with good info on taking Si parts and putting on a HF to convert. Any info will be greatly appreciated. I was wrong it will be 89 si to 91 hf if that makes a difference but i don't think it does
 

MaaseyRacer

Senior Member
lets just put it this way you need a complete head, and block... you will need an ecu, intake and exuast manifold. you will need si hubs too... if i were you i would do this:

the only thing i think the article is missing is that you will need a thicker head gasket, because of the piston/valve clearances...
you can do the full si conversion the all motor HF will be faster though...
 
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I wouldnt want to do the Si swap. You could much easier get a ZC swap for about the sae price and get that extra 10 or 15 hp (can remember how much the si has but the ZC has ruffly 130hp) A shop by my house does ANY swap in any honda you all should check it out WWW.thedropshop.com . Anyway check it out you might want to go a different route after you look at the site.
 

MugenCRX

Senior Member
You do not need a different block for that swap. Im currently in the middle of doing this myself to my CRX. I also posted a question about this swap about the ecu and wiring harness, if your curious about those aspects. Good luck and happy swapping. :ph34r:
 

EFtypeR

Junior Member
Actually the hardware should be your only concern, the HF's and Si's share the same wiring, but not engines or computers. The Si engine will bolt up to your tranny, as well as intake and exhaust, the only thing you will have to change is the ECU. If you want the Si tranny, the you will need the hubs, but the intake and exhaust will be so similar, only 1-2 HP would be gained by swapping. The 4 sp stick has taller gears for forced induction, the Si shorter for NA. Just depends on your long term goals. Do a search on dogpile for HF to Si in an EF. You will find more than you need. Good luck. (btw, hmotors has a sweet B16A1 complete for $1150)
 

bern74

Junior Member
from the factory the hf had 63 hp and the si had 107 so i think i would gain more than 1 to 2 hp and the exhaust are totally different nothing alike the cat is les than 6 inches from block on hf as the one on the Si is under the block not right off the head.
 
if you are going to put an american si motor than you might as well do a JDM sohc ZC it is identical to the us si but has 123hp. and they cost the same. but definetly lose the hf trans.
 
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