I just put together my ZRT Big bore 992, it starts and runs great but tonight I checked the squish and compression, and I am not sure if it is OK. The compression is fine, 142 in each cylinder, but the squish varies by about .005, it is between .064.5 and .070. Is it OK to be off a little in each, or should they be exactly the same squish? Also I think I may have used acid core solder, but I ran it for a whiel afterwords, will this actually do anything? Thanks Alot.

I'd say your fine




Originally posted by fast426@Oct 16 2004, 02:19 AM
I just put together my ZRT Big bore 992, it starts and runs great but tonight I checked the squish and compression, and I am not sure if it is OK.* The compression is fine, 142 in each cylinder, but the squish varies by about .005, it is between .064.5 and .070.* Is it OK to be off a little in each, or should they be exactly the same squish?* Also I think I may have used acid core solder, but I ran it for a whiel afterwords, will this actually do anything?* Thanks Alot.
353452

not sure but, I think the minimum clearance is .074mm under that =detonation...

King, What squish do you run? Don;t you use pump gas with over 200 HP? I did some looking and it seems to me that you don;t really have to worry about detonation til around .050 or so. I talekd witht eh builder and he said it sounds great, so I guess I really just have to wait and see?

fast ,in my thunder my squish is .074, on zrt the squish is more lower but, whit your big bore to 992 probably your squish need to raise at .074 minimum
on my thunder this year I run c12 gas whit high rpm pipe ,this is a set up for race and give to me 220 hp, in trail form I ran cpr pipe and 92 octane gas and raise my hp to 208...210 and squish around .080 for safe trail!!!

King,

What ZRT do you have?

no zrt , tcat 00 whit 01 cdi... this tonight I check my note book for the squish....

ok, that is write on artic book .072 for 900cc and .078 for 1000cc under that is your risk :bash:

How will I know if it is too tight, just look for signs of detonation? Also if I do want to raise it, can I get shims for the sled? Thanks

no shim needed... and at .068 mayby is too tight !!!

Who built the motor? If a performance shop did it then likely the squish is OK. If not and you ventured out into the rewarding but dangerous land of modifications then you'll have to figure it out yourself OR take your specs to a reputable engine builder and have him custom cut the heads (domes, compression and squish) for the application and fuel requirement. There is a lot of power and reliability in doing that.

Race Logic did the machine work and used Wisecos print for the heads, so I have to assume it is good. I am so excited wating though!

Originally posted by rivet@Nov 6 2004, 10:23 AM
Who built the motor? If a performance shop did it then likely the squish is OK. If not and you ventured out into the rewarding but dangerous land of modifications then you'll have to figure it out yourself OR take your specs to a reputable engine builder and have him custom cut the heads (domes, compression and squish) for the application and fuel requirement. There is a lot of power and reliability in doing that.
360649

Squish clearance has little to no effect on octane requirement... The compression ratio , timing,and chamber design are the main players in determining what octane the engine requires to be "safe"..

If you give your engine more squish clearance...you will LOSE reliability ( in your case) along with power..

You need to cc the head on the engine and determine the trapped volume...

Hope this helps

Kelsey


Originally posted by fast426@Nov 6 2004, 10:16 AM
Race Logic did the machine work and used Wisecos print for the heads, so I have to assume it is good.* I am so excited wating though!
360671

Originally posted by RKT@Nov 8 2004, 10:02 AM

If you give your engine more squish clearance...you will LOSE reliability ( in your case) along with power..

361211



What do you mean by this?

Originally posted by fast426@Nov 8 2004, 10:57 AM
What do you mean by this?
361225
A larger squish will not compress the fuel as efficiently as a large squish, and the engine will be much more tempermental to air temp,fuel quality etc.

I run my Mach on 91-93 pump fuel, and my squish is .060-.062. Factory squish was between .066-.068.