Hf motor?

ryangt

Senior Member
in the read onlys i saw that the d15b6 comes in the 88-89 crxs and civics, i have a 90 rex HF that has the same engine, is this right?? or did someone put this engine in the car?

also i read that the hf supposidly is a 8 valve motor, i think pissedoffsol did the article on head swaping onto the hf by changing the 8valve to a 16 valve head.
i have a 16 valve head so im just curious what i bought here. Or if this thing is just stock, was the d15b6 a 16 vlave motor?
please let me know fellas, this thing dosent seem as lacking in power as a normal hf.

any help is much appreciated
 

formby

learning in progress
the dx/std came with a DPFI and the HF/SI came with a MPFI motor and 88-89 are dif than the 90-91 so that might have something to do w/it.......apart from that i have no idea......
 

reckedracing

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are you sure its a D15B6? and not D15B2?

if it is indeed the B6 then my guess is someone just swapped in the long block as a stock replacement...
 

ryangt

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yeah im 100% sure its a d15b6
i dont know why its in this car tho, the guy i bought it from didnt know anything about it. Like i said it runs well and pulls pretty hard and ive driven my fair share of stock rex's and this dosent feel the same.
 

phunky.buddha

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I'm pretty sure all the HFs came with D15B6 engines- and from what I've read up on at different places, the 88-89 were DPFI while the 90-91 were MPFI. I don't know about the valve count. I'm going to have to check my service manuals later.
 

ryangt

Senior Member
well than what the hell did i buy, didnt all si's have vtec and a sunroof? the guy i bought this from had no idea what model it was or anything. it doesnt have any take or emblems so how can i find out exactly what i have because this car does have the d15b6 and its has a 16 valve head on it.
hmm this things buggin me now haah
 

phunky.buddha

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Originally posted by ryangt@Jan 17 2005, 09:25 PM
well than what the hell did i buy, didnt all si's have vtec and a sunroof? the guy i bought this from had no idea what model it was or anything. it doesnt have any take or emblems so how can i find out exactly what i have because this car does have the d15b6 and its has a 16 valve head on it.
hmm this things buggin me now haah
[post=447192]Quoted post[/post]​


Every CRX Si had a sunroof.

Did you pull the valve cover to make sure you had 16 valves? I'm just checking. Do you have MPFI? All the DX engines from 88-91 only had DPFI.
 

ryan89crx

Senior Member
Originally posted by Calesta@Jan 17 2005, 03:16 PM
the 88-89 were DPFI while the 90-91 were MPFI.
[post=447030]Quoted post[/post]​

my 89 HF is mpfi, i did a motor swap and no converting needed
 

phunky.buddha

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Originally posted by ryan89crx+Jan 17 2005, 10:36 PM-->
@Jan 17 2005, 03:16 PM
the 88-89 were DPFI while the 90-91 were MPFI.
[post=447030]Quoted post[/post]​

my 89 HF is mpfi, i did a motor swap and no converting needed
[post=447214]Quoted post[/post]​

Cool. Thanks for putting the correct info out there. I thought they were all MPFI too, but some of the engine lists out there have the 88-89 as DPFI.
 

jlicrx

Senior Member
Originally posted by Calesta@Jan 17 2005, 04:16 PM
I'm pretty sure all the HFs came with D15B6 engines- and from what I've read up on at different places, the 88-89 were DPFI while the 90-91 were MPFI. I don't know about the valve count. I'm going to have to check my service manuals later.
[post=447030]Quoted post[/post]​

all 88-91 HFs are D15B6 - all are MPFI - all had 8 valves
all DX and LX are D15B2 - all are DPFI - all had 16 valves
 

phunky.buddha

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Originally posted by jlicrx+Jan 17 2005, 11:39 PM-->
@Jan 17 2005, 04:16 PM
I'm pretty sure all the HFs came with D15B6 engines- and from what I've read up on at different places, the 88-89 were DPFI while the 90-91 were MPFI. I don't know about the valve count. I'm going to have to check my service manuals later.
[post=447030]Quoted post[/post]​

all 88-91 HFs are D15B6 - all are MPFI - all had 8 valves
all DX and LX are D15B2 - all are DPFI - all had 16 valves
[post=447234]Quoted post[/post]​


:thumbsup:

I never took my D15B6 apart- I just threw it in the dumpster before I moved.
 

reckedracing

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you can also search for the VIN "translation" to find out what model it was when new and what motor was suspossed to be in it
 

ryan89crx

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Originally posted by jlicrx@Jan 17 2005, 09:39 PM
all 88-91 HFs are D15B6 - all are MPFI - all had 8 valves

[post=447234]Quoted post[/post]​

true, i also think that the hf all motor moster article on this site is incorrect, because putting a 16 valve head on a motor that only has 2 valve reliefs per piston seems like trouble to me...
 

phunky.buddha

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If the piston is short enough to not require valve reliefs at all, then it won't even matter... but I've never seen an HF piston.
 

Riceras

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I was just wondering about that yesterday... There is only 2 Valve Reliefs on an HF Piston how much clearance is there from the Piston to the Valve! Is it dangerous or is there enough room to not have to worry about it! Also if there was 4 valve relief piston that was only 2 valve head wouldnt that murder your CR???
 

reckedracing

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because putting a 16 valve head on a motor that only has 2 valve reliefs per piston seems like trouble to me...


correct me if i'm wrong here but i think thats the whole idea behind the hf all motor monster... you are increasing the compression ration because you only have 2 valve relieves instead of 4...


Also if there was 4 valve relief piston that was only 2 valve head wouldnt that murder your CR???

yes, but you can always have the head milled
 

ryan89crx

Senior Member
but wouldnt increasing the compresion ration bring the piston closer to the head. and if that happens there need to be space for the valves to go, other than through the piston. i know that the reliefs are there for a reason, if they werent needed, why would honda use them?

i dunno, maybe someone need to clay this setup and find out for sure
 
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