crx hf/si questions

Ok i have a 91 hf, and am planning on swapping in a b series at some point before next summer. My first questions reguarding that are....

Are the si and hf wiring harness's the same. Meaning i have swapped a b16 into an si using the si harness, would i be able to do the same with the hf.

Are the axles the same....same thing swapped b16 with si hubs, will hf hubs work.

Now for questions for my plans for now. I have a free si head and intake mani. The head needs new valves and thats it. Can i put this head on my hf block without any problems. Or could i just put the si intake manifold on my engine?

Last question, i have the stock hf engine in my car now, but i have an L3 tranny, i thought the L3 was just the si tranny, am i wrong or do i have an si tranny?

Thanks in advance

i just had a big ordeal just to find out that the inner axel splines(where they hook into the trannie). are the same so if it askes for si axels you can use you hf axels but by switching the hubs you can switch axels and have stronger axels.

you know for a quick and cheep boost in speed just put in a dx ecu it'll increase your horsepower from 70 to 92, i did it and it's nice, i think if you have a 5 speed trannie it's an si or dx trannie, but i'm not a pro in this. in fact i'm just guessing.

and i'm preitty sure you have to get an si wiring harnass cause that's linked up for mpfi your hf has dpfi but the seccond one is only used for starting the car so technically you have really crappy single point fuel injection.

hope my miniscule knowlege helps, i'm gonna chill now :smokin:

Actually i have mfpi with my hf

which ecu do you have?

Im guessing the stock hf ecu.

I just bought my car on the first of august, the engine was swapped out for a rebuilt hf engine by the previous owner 3 years ago, and has about 90k on it. The tranny says L3 on it. So im pretty sure the ecu was left stock. Long story on why the engine was changed out.

HF did indeed have MPFI and they should share the same wiring harness, im almost positive. Also, the L3 stamped on your tranny doesnt mean you have an Si tranny. All D-series trannys are generically known as L3 because thay all have that stamp on them. Here is avery resourceful site about L3 trannys http://www.d16a.com/d_series_trannys.htm

hey 91civichatch2571 could he simply put in an si ecu for better performance? cause i know you can put in a dx ecu in a std civic to get slightly better performance mabey that could help him out while he thinds about stuff, plus i'm just interested.

hey 91civichatch2571 could he simply put in an si ecu for better performance? cause i know you can put in a dx ecu in a std civic to get slightly better performance mabey that could help him out while he thinds about stuff, plus i'm just interested.

I suppose he could, but I dont think it would help much, it might actually be worse. The intake manifold on HF's are extremely restrictive and dont let much air in at all. If you try to add more fuel (by putting in the Si ECU), it just wouldnt run right. The only way for him to get anywhere near the power of an Si without swapping engines would be to put the Si head on the HF block using the Si ECU. It wouldnt be as powerful as the 1.6 Si but it really would add a few HP.

bah the si head will not work on the stock hf block as the hf pistons are knotched for an 8 valve head! yes the hf manifold is very restrictive! and all hf models have mpfi. hf axles are 23 spline.....when switching to a b series engine tranny combo you will need to get either dx or si hubs to use the 26 spline axles. yes you can add the si intake mani to your engine with no probs. except the si mani will not have the egr valve that the hf mani has. so if your using the hf ecu you will have a CEL light on. and yes L3 means 88-91 tranny. only way you can for sure tell what you have is to look on the inside of the tranny. ie cound the fina drive gears. hf=2.9 or 3.2 dx=3.8 si=4.2.....

I thought that the axle splines were only different on hf's on 88-89's. I should be ok without the egr hooked up correct, i mean if the intake mani doesn't have on it should run fine without one right. I don't really care about the tranny, just curious. Like i said i am swapping a b-series in sometime in the next 6 months. So the hf harness will work with a b-series provided that i get the vtec harness. And i guess i need hubs too. What exactly am i going to need to do an integra front and rear brake conversion? I've got some place i can get everything, just need to know what exactly i need....for the front and the rear. Also is it really necissary for me to replace the mbc, because i've got a brand new one on my car and don't really feel like messing with it.