hey guys ive read lots of stuff about DCR and im trying to decide what people have had success with on a N/A motor running 91 octane. i know there are a lot of other variables in this equation but im just trying to get a feel for whats been actually run out there.

 

Ya can't just stick 9.1+ in a motor without doing the other thing's it takes to run that high---- It don't work like that.

 

I'm running at 8.8 or so with a Ross flat top piston and low .04x quench. My heads are ported as well (no hot spots) and I'm running a plug with a heat range one step colder than stock. It hasn't hit summer yet so I'm not sure what the Texas heat will do, but right now it runs good.

 

1racerdude i realize you cant just up the compression and im not looking at anywhere near 9.1 DCR, i just want to see whats attainable as im trying for 8.6-8.8.
-im planning on smoothing the cumbustion chambers so no hot spots,
-running the engine cooler with a 160 thermostat and tune
-pulling some timing out
-switching to one step colder plug
-this is all going with new internals and cylinder boring to start with.
-what else should i look at for running a higher compression?
thanks

 

There are several.
One is a .035-.040 quinch and ya can't do that unless ya "0"deck the block.
Like I told ya several times static ain't s*** it's the DCR that counts.

 

I'm at 8.3 DCR, 11.6 SCR, and .034 quench.

Dean

 

umm around 7.6 on accident.

 

im confused where have i said anything about static? everything ive posted is in relation to dynamic compression. also this may be a stupid question for most people but exactly what is quench? i assume it has to do with the head gasket and how far the piston is from the top of the cylinder isnt stock like .025, and how does that relate to having to "0" decking the block? sorry if that seems like a stupid question but im really trying to get all this stuff straight.

 

and im going to use the felpro head gaskets which i think are .039 thick, just for more information dealing with the quench part and decking the block.

 

If ya got .039 gasket and a "0" block ya got .039 quinch which is below .040 and fine if ya deck the block.
If ya leave it .025 in the hole it's .064 quinch and that's NOT allright with a high DCR.It will probably rattle it's *** off.

 

well crap. im in trouble then, id have to take my heads to 61cc to maintain a 8.8 DCR with my home head port. i take it would probably be difficult to remove that much material without running into trouble? is there any other options? i guess this is the one MAJOR thing ive over looked, hopefully the only one.

 

Head back over to the KB Pistons website and scroll to the bottom of the page...

http://kb-silvolite.com/article.php?action=read&A_id=35

In the "Technical Stuff" area, read the articles for a better understanding. They're pretty well written.

"0" deck simply means that the deck surfaces of the block are machined such that the piston top is flush when it reaches Top Dead Center (TDC). All of this stuff is simple addition and subtraction once you understand what's going on.

-Mindgame

 

If ya haven't bought the pistons ya can get a dish. If ya have bought them ya can send them back.
Do as MG suggested and read up on it and refigure your DCR with different dish pistons.

 

just got done reading and wow what an article that was one of the most informationally helpful articles ive read in a long time. thanks for the link. okay so im going to have to have the block 0 decked. is this accomplished by mock up measure and dissasembly? is there anyway to get it right without putting the crank in? also nobody comented on how many cc's can be taken out of the heads realitively easy? thanks guys i just about screwed up putting this thing together with .60 quench.

 

No way to get it right without a mockup, and make sure all 4 corners are done so you can "square deck" the block, production blocks are not the same end to end or corner to corner. You have to use the crank, rod, piston combo you are going to run to do the mockup.


David