Evaluate my engine combo plz...
Thread Starter
Registered User
Joined: Jul 2001
Posts: 221
From: Raleigh, NC
Evaluate my engine combo plz...
Ok, I have just purchased a 1992 Corvette with the following engine mods:
.030 over
Align honed, decked, and squared
Ported oil return passages
Cast steel SCAT 383 crank
4340 H beam forged rods
Forged Pistons (10:1, but final compression ratio comes to almost 11:1 with heads and block decked)
Jones competion cylinder heads, professionally ported. 2.00/1.54 valves.
LT4 hotcam with install kit (new lifters, pushrods, and springs)
Full roller rockers
Port matched LT1 intake
Misc. headers and borla catback
Other stuff-
New opti (Grrr, stupid Opti)
Newly surfaced Fly Wheel and new pressure plate
24 lb/hr fuel injectors
AFPR
750 CFM TB
Tuned with tuner cat
The engine builder said the motor was built for N20 so the pistons have an extra 5 thousandths of clearance. I've never heard of that before, what's that all about.
Thanks a bunch guys!
.030 over
Align honed, decked, and squared
Ported oil return passages
Cast steel SCAT 383 crank
4340 H beam forged rods
Forged Pistons (10:1, but final compression ratio comes to almost 11:1 with heads and block decked)
Jones competion cylinder heads, professionally ported. 2.00/1.54 valves.
LT4 hotcam with install kit (new lifters, pushrods, and springs)
Full roller rockers
Port matched LT1 intake
Misc. headers and borla catback
Other stuff-
New opti (Grrr, stupid Opti)
Newly surfaced Fly Wheel and new pressure plate
24 lb/hr fuel injectors
AFPR
750 CFM TB
Tuned with tuner cat
The engine builder said the motor was built for N20 so the pistons have an extra 5 thousandths of clearance. I've never heard of that before, what's that all about.
Thanks a bunch guys!
Registered User
Joined: Apr 2003
Posts: 2,628
From: Pgh, PA
The extra .005 clearence is because with N20 then egnine heats up more, and obviously as it heats it expands, So the extra clearence keeps the engine from wearing as hard as a regularly clearenced motor when spraying ... Sounds like a hard Vette 
... I think if i was you id start with a 75, to make sure its all good , and work your way up to the 200ish range? Hehe spray is good ...
... I think if i was you id start with a 75, to make sure its all good , and work your way up to the 200ish range? Hehe spray is good ...
Spray away my good man 
Registered User
Joined: Jan 2002
Posts: 442
From: Houston, TX
What length are the rods, and what is the deck height of the pistons? 6" rods give a 1.113 deck height, which isn't ideal for a lot of nitrous, so hopefully they used 5.7's. Also, what brand are the pistons? I assume at the very least they are forged since the words nitrous where used from this engine builders mouth.
Also, where is the extra .005 clearance? There are lots of details left out. It could be a decent motor, but you need to go more into detail with the blueprint specs. I raise a serious red flag with the extra ".005" piston clearance". You need to know where that clearance is. If that's piston to bore clearance, unless you have JE, Wiseco's, or even Ross, you are asking for piston skirts to break.
Later
Chuck
Also, where is the extra .005 clearance? There are lots of details left out. It could be a decent motor, but you need to go more into detail with the blueprint specs. I raise a serious red flag with the extra ".005" piston clearance". You need to know where that clearance is. If that's piston to bore clearance, unless you have JE, Wiseco's, or even Ross, you are asking for piston skirts to break.
Later
Chuck
Last edited by chucks97ss; Jul 22, 2003 at 07:07 PM.
Registered User
Joined: Apr 2003
Posts: 2,628
From: Pgh, PA
Ive heard of engines being built like that before. And from what i understood it was extra ring gap clearance ... However, i dont thnk it would break piston skirts if it was .005 would it? I mean i could see it breaking them if your spinning really fast like say over 7K ... but could .005 really break piston skirts ? Not trying to criticise , im jsut asking so dont take it the wrong way man lol
Registered User
Joined: Jan 2002
Posts: 442
From: Houston, TX
Originally posted by HardcoreRM125
Ive heard of engines being built like that before. And from what i understood it was extra ring gap clearance ... However, i dont thnk it would break piston skirts if it was .005 would it? I mean i could see it breaking them if your spinning really fast like say over 7K ... but could .005 really break piston skirts ? Not trying to criticise , im jsut asking so dont take it the wrong way man lol
Ive heard of engines being built like that before. And from what i understood it was extra ring gap clearance ... However, i dont thnk it would break piston skirts if it was .005 would it? I mean i could see it breaking them if your spinning really fast like say over 7K ... but could .005 really break piston skirts ? Not trying to criticise , im jsut asking so dont take it the wrong way man lol
Standard piston to bore clearance on a normal forged piston is .004-.006 thousanths. Add another .005 on top of that, and yeah, you could have some issues unless you have really good pistons. It's called piston slap. Has nothing to do with piston rings. You are probably correct about the extra .005" being in the piston ring gap though, so what I'm talking about is totally unrelated. A person just needs much more info before they can go and tell this person that is a good motor.
Later
Chuck
Banned
Joined: Aug 2001
Posts: 3,505
From: looking for a flow bench so Brook and I can race
all that money for and a hot cam?
but thats just my personal opinion.
I've been "sold" on the high lift theory but thats just me.
6'' rods are a good thing in a nitrous IMHO.
new fuel pump is a good idea with nitrous. walpro 325 or something like that is like $130. easy install.
but thats just my personal opinion.I've been "sold" on the high lift theory but thats just me.
6'' rods are a good thing in a nitrous IMHO.
new fuel pump is a good idea with nitrous. walpro 325 or something like that is like $130. easy install.
Banned
Joined: Aug 2001
Posts: 3,505
From: looking for a flow bench so Brook and I can race
Originally posted by 96-speed
All that money for stock heads?
All that money for stock heads?
http://www.worldisround.com/articles/18770/photo36.html
http://www.worldisround.com/articles/18770/photo37.html
http://www.worldisround.com/articles/18770/photo38.html
http://www.worldisround.com/articles/18770/photo39.html
http://www.worldisround.com/articles/18770/photo40.html
http://www.worldisround.com/articles/18770/photo41.html
http://www.worldisround.com/articles/18770/photo42.html
http://www.worldisround.com/articles/18770/photo43.html
http://www.worldisround.com/articles/18770/photo44.html
edit:
besides, it doesn't matter. my car isn't real and it wont ever be done
