New to engine building, have a couple questions
05-14-2008, 02:01 PM
#1
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New to engine building, have a couple questions Please don't flame or tell me to search, because I've done this. I'm getting ready to build a LQ4, budget oriented of course. I'm gonna leave the bottom end alone other than cleaning up. I'm planning on running 243's that are cleaned up. My first question is, is there a gasket I can run to acheive close to 10.5 CR without milling the heads? Also how will this affect my PTV clearance? I'm looking to get near 500whp through those heads and a vic jr. I am also wondering what kind of cam would do this while retaining decent street manners.
Thanks in advance
Kris
Thanks in advance
Kris
05-14-2008, 04:04 PM
#2
If your building an engine, look up piston specs for compression when used with the 243 65cc head. The last thing you want to do is mill the head if your looking for 10.5:1. I would suggest going a little higher on a stroker application, but its your choice.
Theres allot you need to pay close attention to if your assembling this yourself. Your best bet is to call and engine builder, and have them build a package for you to ensure you are getting the correct components.
Theres allot you need to pay close attention to if your assembling this yourself. Your best bet is to call and engine builder, and have them build a package for you to ensure you are getting the correct components.
05-14-2008, 05:01 PM
#3
here is a good compression calculator that you can use to determine the gasket thickness and compression.
http://www.rbracing-rsr.com/compstaticcalc.html
http://www.rbracing-rsr.com/compstaticcalc.html
05-14-2008, 05:14 PM
#4
Assuming you have a bone stock lq4, which is stock compression with 72cc heads is 9.4:1. This is a 4" bore, 3.622 stroke, .055 head gaskets, -.007 in hole, about 3cc dish pistons, 72cc heads
Now with your 65cc heads and a .040 gasket you would have 10.6 :1 which i think is a good compression. Also the .040 gaskets will give you a better quench distance and get a better burn in the chambers. Make sure to use 4" bore gaskets .040 thick. Tim
Now with your 65cc heads and a .040 gasket you would have 10.6 :1 which i think is a good compression. Also the .040 gaskets will give you a better quench distance and get a better burn in the chambers. Make sure to use 4" bore gaskets .040 thick. Tim
05-14-2008, 07:32 PM
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If your building an engine, look up piston specs for compression when used with the 243 65cc head. The last thing you want to do is mill the head if your looking for 10.5:1. I would suggest going a little higher on a stroker application, but its your choice.
Theres allot you need to pay close attention to if your assembling this yourself. Your best bet is to call and engine builder, and have them build a package for you to ensure you are getting the correct components.
Theres allot you need to pay close attention to if your assembling this yourself. Your best bet is to call and engine builder, and have them build a package for you to ensure you are getting the correct components.
05-14-2008, 07:39 PM
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Assuming you have a bone stock lq4, which is stock compression with 72cc heads is 9.4:1. This is a 4" bore, 3.622 stroke, .055 head gaskets, -.007 in hole, about 3cc dish pistons, 72cc heads
Now with your 65cc heads and a .040 gasket you would have 10.6 :1 which i think is a good compression. Also the .040 gaskets will give you a better quench distance and get a better burn in the chambers. Make sure to use 4" bore gaskets .040 thick. Tim
Now with your 65cc heads and a .040 gasket you would have 10.6 :1 which i think is a good compression. Also the .040 gaskets will give you a better quench distance and get a better burn in the chambers. Make sure to use 4" bore gaskets .040 thick. Tim
Last edited by can'tfindausername; 05-14-2008 at 07:58 PM.
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05-14-2008, 08:15 PM
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The more important part of gasket thickness is everything in relation to your deck clearance. You want to achieve .040" quench distance. Thats the way you should be looking at it, going thinner on a gasket in terms of compression is a road I try to stay away from.
I had a customer put .027" cometic gaskets in his motor, lasted 1 dyno run, 2nd dyno run bottom end fell apart, pistons were hitting the cylinder heads . pistons were .010" out the deck.
I had a customer put .027" cometic gaskets in his motor, lasted 1 dyno run, 2nd dyno run bottom end fell apart, pistons were hitting the cylinder heads . pistons were .010" out the deck.
05-15-2008, 12:12 AM
#9
The more important part of gasket thickness is everything in relation to your deck clearance. You want to achieve .040" quench distance. Thats the way you should be looking at it, going thinner on a gasket in terms of compression is a road I try to stay away from.
I am not sure about the dish of the piston, but do know that the stock compression is 9.4:1 so i used 3cc dish and pistons .007 in the hole. If the pistons are infact a 6cc dish then the pistons are .03 out of the hole.
Comes out the same in then end. Either way you look at it, your shortblock, 65cc heads and a .040 gasket will be around 10.6:1
05-17-2008, 08:07 AM
#10
The more important part of gasket thickness is everything in relation to your deck clearance. You want to achieve .040" quench distance. Thats the way you should be looking at it, going thinner on a gasket in terms of compression is a road I try to stay away from.
I had a customer put .027" cometic gaskets in his motor, lasted 1 dyno run, 2nd dyno run bottom end fell apart, pistons were hitting the cylinder heads . pistons were .010" out the deck.
I had a customer put .027" cometic gaskets in his motor, lasted 1 dyno run, 2nd dyno run bottom end fell apart, pistons were hitting the cylinder heads . pistons were .010" out the deck.
05-21-2008, 12:53 PM
#11
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well I found out the stock dish is 6.7cc....so with a .040" head gasket I should be good to go correct? That would put stock deck height at around -.006" So my quench should be good along with my compression ratio. Am I thinking correctly? If that calculator that was posted is close...I should be at almost 10.5:1 (10.47 actually)
