Yo. This week I'm experimenting with high compression(12.0:1) in my crx that nobody seems to want. After compression experimenting with high compression, I will slowly turn up nitrous to see what volume of nos stock internals will tolerate. I'm trying to decide whether I should go with mpfi before or after the head milling. If anyone has done this before, feel free to post your experiences, and what I might run into . I'll be sure to keep those of you who care(if any) informed .

 

well i will start things off. there arent very many people on this site, mainly in the all motor forum that have spent much time with high compression sohc's. i think you are going to run into detonation problems if you try to run it on 91 or 92 octance. you might be able to get around this by retarding ignition timing. here is what i would suggest for this motor if you want it to last more than a one gear pull, run some high octane fuel and retard your ignition timing. good luck

 

They don't have 91 around here, so with stock copmression, I use 93 anyways. I think 93 should work fine until i use nitrous, then I'll use some octane booster. This is mainly an experiment to see how much more power will be attained, and how long the internals will last before spray, or after spray. thanks for the input dude.

 

bump

 

get some vx pistons and you can really mess around with CR by being able to use any 1.6 pistons or even used a aftermarket piston if you want. Being you using No2 you'd want strong pistons since the stocker will melt if you shoot to much. Just screw that No2 stuff and build a nice 1.5 screamer with that block and put some vx rods and some p2e pistons or pm7 pistons but you'll be at a super high CR and then slap a vtec head on it and for not that much you'll have a nice setup. Just get that **** tuned or it won't last long with that high of a CR.

 

why VX rods?? they are 2mm longer than other sohc rods and not any stronger.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by lohatch &raquo;</TD></TR><TR><TD CLASS="quote">why VX rods?? they are 2mm longer than other sohc rods and not any stronger. </TD></TR></TABLE> They have higher compression.
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by egizzle6 &raquo;</TD></TR><TR><TD CLASS="quote">get some vx pistons and you can really mess around with CR by being able to use any 1.6 pistons or even used a aftermarket piston if you want. Being you using No2 you'd want strong pistons since the stocker will melt if you shoot to much. Just screw that No2 stuff and build a nice 1.5 screamer with that block and put some vx rods and some p2e pistons or pm7 pistons but you'll be at a super high CR and then slap a vtec head on it and for not that much you'll have a nice setup. Just get that **** tuned or it won't last long with that high of a CR.</TD></TR></TABLE>What kind of tune are you talking about, A/F ratios? You'll have to fill me in on what those pistons are you're talking about. As far as internals go though, I'm trying to find out they're stress tolerance for boost in the future. If I'm going to pull the rods, thats basically the same as rebuliding the engine, because then I'll have to change bearings. A d15 ain't worth it, IMO. I was thinking of getting an exhaust gas temp gauge though. Would the pistons melt because of friction, or combustion temp, or both? If both, from experience by examination of the melted piston, You should be able to tell which one contributed more to the melting. Let me know. thx

 

the pistons are going to fail due to detonation most likely. you are going to burn a valve before you melt a piston. i realize the VX rod is going to raise compression. i also realize that you dont want to tear into the block. this motor is going to fail due to lack of tuning IMO.

 

I changed my mind, **** that stuff. I have to get the piston valve reliefs modded to not hit the valves on exhaust stroke. I'm just gonna see how well it holds up to no2 and how much for how long.

 

i have heard that by using VX rods you can use d16 pistons? people say the JDM D15B VTEC is basically a VX bottom end with P28 pistons.

is this true?