Drivetrain JCW +.3mm head gasket
#1
08-23-2017 | 06:12 AM
Thread Starter
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3rd Gear
Joined: Feb 2016
Posts: 156
Likes: 5
From: SC
JCW +.3mm head gasket
Some of you may have read my other thread and my current troubles.
This thread is an extension of that, but mainly some education.
I am stilllllllll waiting for the engine mentioned above to be diagnosed for it's fault. While that is happening, I have had another engine built up. But, I have not decided on what head gasket to use. With choosing the Mahle 77.5mm, 10.5 CR piston set, instead of trying the CP's again, they don't have a lower CR set avail. So, I am stuck with a stock-ish setup.
So, here are my questions to you all... do I go back with a stock thickness head gasket, or the thicker JCW +.3mm one? Does it lower the CR by the actual .5 like is widely claimed (or even .25)? Is that really enough to matter? With DI engines, does quench area really play a part? Can the dome and valve shroud area be cleaned up to address any issues with this that may arise?
My goals with this car are to keep it an efficient daily driver, but make it more fun with a mild tune (~17psi). CAI and larger, stepped-core IC already installed. Catless DP will be installed when the car goes back together. I am also going to ask the tuner (probably Manic) to lower the coolant temp to help combat any heat induced knock.
Thoughts? Critiques?
This thread is an extension of that, but mainly some education.
I am stilllllllll waiting for the engine mentioned above to be diagnosed for it's fault. While that is happening, I have had another engine built up. But, I have not decided on what head gasket to use. With choosing the Mahle 77.5mm, 10.5 CR piston set, instead of trying the CP's again, they don't have a lower CR set avail. So, I am stuck with a stock-ish setup.
So, here are my questions to you all... do I go back with a stock thickness head gasket, or the thicker JCW +.3mm one? Does it lower the CR by the actual .5 like is widely claimed (or even .25)? Is that really enough to matter? With DI engines, does quench area really play a part? Can the dome and valve shroud area be cleaned up to address any issues with this that may arise?
My goals with this car are to keep it an efficient daily driver, but make it more fun with a mild tune (~17psi). CAI and larger, stepped-core IC already installed. Catless DP will be installed when the car goes back together. I am also going to ask the tuner (probably Manic) to lower the coolant temp to help combat any heat induced knock.
Thoughts? Critiques?
#2
08-23-2017 | 07:01 AM
Hi John
The JCW head gasket lowers compression by .25 instead of the .5 mentioned. In addition the Mahle Powerpack pistons are actually 10.3:1. So combining the two will put you at 10:1 same as a JCW. That's a good number for a fast daily driver. The Manic stage 2 or a custom tune can drop your coolant temps to 85.5 C. Check the Manic website for your closest dealer but if your in Florida I can help you out.
The quench area shouldn't be a big concern. Ive seen it run it as high as .058" without knock issues on the Prince engine. With the JCW gasket your quench should be around the .045" mark IIRC. On the combustion chamber just a simple polish is all it needs. Shrouding is not an issue even if you go 1mm larger on intake and exhaust. If polishing it yourself don't forget to cc the chambers. A piece of plexiglass, some grease and a 50cc syringe will be your friend.
The JCW head gasket lowers compression by .25 instead of the .5 mentioned. In addition the Mahle Powerpack pistons are actually 10.3:1. So combining the two will put you at 10:1 same as a JCW. That's a good number for a fast daily driver. The Manic stage 2 or a custom tune can drop your coolant temps to 85.5 C. Check the Manic website for your closest dealer but if your in Florida I can help you out.
The quench area shouldn't be a big concern. Ive seen it run it as high as .058" without knock issues on the Prince engine. With the JCW gasket your quench should be around the .045" mark IIRC. On the combustion chamber just a simple polish is all it needs. Shrouding is not an issue even if you go 1mm larger on intake and exhaust. If polishing it yourself don't forget to cc the chambers. A piece of plexiglass, some grease and a 50cc syringe will be your friend.
#3
08-23-2017 | 07:21 AM
Thread Starter
|
3rd Gear
Joined: Feb 2016
Posts: 156
Likes: 5
From: SC