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Which Is A Better Head

Started by kodi191, Mar 12 2010 11:37 AM

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16 replies to this topic

#1
kodi191
Posted 12 March 2010 - 11:37 AM

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I have an 87 crx with a carbed d15 with the 8 valve head and I have an 86 crx with the carbed 12 valve head and I am wondering which one has more potential for power. I plan to port and polish and maybe shaving the head, but I dont know which one would be easier to work with.

#2
zakats
Posted 12 March 2010 - 12:22 PM

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well... the 12 valve head is better by leaps and bounds BUT they're both still crappy CVCC heads. don't get me wrong the CVCC setup was a marvel of its time and performs well, but it isn't great for performance. The Si or Canadian DX heads both lacked CVCC and are easiest to work with- both are 12 valve configurations.
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#3
Maine_Honda_Racer
Posted 12 March 2010 - 12:52 PM

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Like Zak said, either an Si head of a Canadian non CVCC head would be your best bet. The others are not very effective for making power. A non CVCC head with some good work will flow nicely and support some decent power.

Ben


QUOTE (cbstdscott @ Feb 28 2010, 10:43 PM) <{POST_SNAPBACK}>
In fact, I rock out an RPR decal!

#4
Sgt. Pepper
Posted 12 March 2010 - 05:20 PM

I don't have an answer to your question, but I corrected your grammer and spelling. You are welcome.
Adding power makes you faster in the straights. Subtracting weight makes you faster everywhere. - Colin Chapman

#5
Vicious
Posted 12 March 2010 - 05:23 PM

laugh.gif you just made my crappy day worthwhile sarge

as for the topic you'll want the cdm fi head. it's supposedly the best flowing from factory. i never really found out why just what i read.

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#6
jsgprod
Posted 12 March 2010 - 06:02 PM

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^^ This biggrin.gif .

It has the best combustion chamber. As for the ports and flow, I don't think there's any difference between it (PE3) and the Si (PE7) head...Oh, I forgot. The Canadian DX head has a slightly smaller exhaust valve than the Si head (32mm vs 33mm).

Seeing as you're in West Virginia, normally I'd suggest finding an Si head and installing that. But you mentioned that you have an 87 1.5 with the 8 valve head, which means you have an HF motor. I would not recommend putting a non CVCC head on an HF motor for a high performance upgrade. It won't last long, the rods aren't strong enough.

Best low buck suggestion if you're looking at performance... a D16A swap.

If you just want a little more performance and aren't worried about fuel mileage...swap in a DX or Si transmission. Trust me, it'll work. wink.gif

But don't lose that HF gearbox until you let me know what your cars serial # is!

Jay

If you love the Elise, drive a Se7en - Caterham or whatever...
It has even less content than the Elise, is less graceful looking
...and changes direction like a ping pong ball whacked by Thor.

scull+gif+1.gif

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#7
Vicious
Posted 12 March 2010 - 06:19 PM

jay, i'm sure you know off the top of your head the stamping on the cdm fi head right? i bought a head a few months back which was supposed to be a cdm head and then i get it and open it up and lo and behold it's a pe7 dry.gif

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#8
jsgprod
Posted 13 March 2010 - 09:04 AM

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QUOTE (Vicious @ Mar 12 2010, 07:19 PM) <{POST_SNAPBACK}>
jay, i'm sure you know off the top of your head the stamping on the cdm fi head right? i bought a head a few months back which was supposed to be a cdm head and then i get it and open it up and lo and behold it's a pe7 dry.gif


Yeah, but it's real easy to tell the difference (as long as you can see it before you buy it).

Over the 3/4 exhaust ports:


And the combustion chamber is not round like it is in an Si head.

If you love the Elise, drive a Se7en - Caterham or whatever...
It has even less content than the Elise, is less graceful looking
...and changes direction like a ping pong ball whacked by Thor.

scull+gif+1.gif

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#9
Vicious
Posted 15 March 2010 - 08:40 PM

yeah i know i should have asked for pics but since the seller lived in canada and pulled it from an si i didn't think to bother asking for pics.

Thanks,
-Jay

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#10
zakats
Posted 16 March 2010 - 12:09 AM

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QUOTE (jsgprod @ Mar 12 2010, 06:02 PM) <{POST_SNAPBACK}>
But don't lose that HF gearbox until you let me know what your cars serial # is!

Jay

you STILL haven't found that high altitude hf box yet?!
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#11
jsgprod
Posted 16 March 2010 - 07:09 AM

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QUOTE (zakats @ Mar 16 2010, 01:09 AM) <{POST_SNAPBACK}>
you STILL haven't found that high altitude hf box yet?!


Nope, not having a lot of expectation of ever finding one either. At least not one that someone would be willing to part with.

If you love the Elise, drive a Se7en - Caterham or whatever...
It has even less content than the Elise, is less graceful looking
...and changes direction like a ping pong ball whacked by Thor.

scull+gif+1.gif

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#12
Vicious
Posted 16 March 2010 - 07:35 AM

what's the serial # supposed to be? i know i have two hf trannys i could check out for you as long as you're talking about the the number on the tranny on the little plate. if either one turns out to be the one you need just let me know i'll i'll get it to you.

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#13
jsgprod
Posted 16 March 2010 - 10:30 AM

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Those tags won't have anything to do with what's inside the gearbox. At least I have never found that they did over the past 24 years. From what I've heard about the later models and the tags they put on them, they're pretty reliable. Just never found that they were of much use in the earlier models like ours.

The only way I've ever discovered what's in them is to disassemble them and count teeth. dry.gif

Jay

And what end cover is on them will determine what length the mainshafts are (later or earlier 'box). Easy to tell that, I made a post about it a couple years ago.

If you love the Elise, drive a Se7en - Caterham or whatever...
It has even less content than the Elise, is less graceful looking
...and changes direction like a ping pong ball whacked by Thor.

scull+gif+1.gif

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#14
kaymo
Posted 16 March 2010 - 10:32 AM

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wouldnt your VIN tell if its a high alt car?
QUOTE (kjeffery @ Apr 17 2009, 06:17 PM) <{POST_SNAPBACK}>
Yet again Scott, you have all the answers

QUOTE (cbstdscott @ Apr 17 2009, 07:31 PM) <{POST_SNAPBACK}>
No. All the answers are in the Kakabox build thread.

QUOTE (Lymitliss @ May 26 2009, 08:06 PM) <{POST_SNAPBACK}>
Ohh yeah I guess that makes sense. King Kaymo has all the answers :lol:

#15
jsgprod
Posted 16 March 2010 - 10:50 AM

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QUOTE (kaymo @ Mar 16 2010, 11:32 AM) <{POST_SNAPBACK}>
wouldnt your VIN tell if its a high alt car?


Sure, but it won't help if the gearbox is out of the car and the car isn't around any longer.

Seventh digit of the serial number, if it's a 9, it's a HiAlt car.

If you love the Elise, drive a Se7en - Caterham or whatever...
It has even less content than the Elise, is less graceful looking
...and changes direction like a ping pong ball whacked by Thor.

scull+gif+1.gif

jsgprods Gallery

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