Would like opinions on running this piston to valve clearance
04-01-2013, 09:27 PM
#1
Would like opinions on running this piston to valve clearance I currently have the SNS Torque Max Stage 2 cam installed on my 02 WS6 with my stock 241 heads. I am going to purchase the Advanced Induction Dart/RHS 223cc heads; more than likely tomorrow. I've been e-mailing back and forth with Phil and based on the intake and exhaust clearance numbers I have with the cam and my stock 241's, Phil said I can have the AI Dart/RHS heads milled to 59cc, which will give me right at .050 clearance on the intake side. I will be running stock OE gaskets. I believe he said that would give me right at 11:25 compression. My question to you guys is this: Would you feel safe running around .050 clearance on the intake side? My car is a M6. I want to run the highest compression possible because I know that is going to yield me the most torque. Should I go with the 59cc option, or opt to go with something a little safer, say 61cc? Would there be that much of a difference between 59cc and 61cc?
04-01-2013, 09:46 PM
#3
Yeah, I know it's less than text book. I'm in a tough place because I want to run high compression for the added torque and power, but don't want to flycut the pistons. I think if I went with 61cc or even 62cc, that would give me a hair over .060 intake clearance, which would be a little safer. I'd love to hear other opinions.
04-01-2013, 10:49 PM
#4
Well, you'd lose around .3 points of compression and gain a hair over .010" of clearance. What would that do to your power? You might lose 5-7rwtq and a few ponies for a little bit more clearance. The thing to remember is you are going to have a lot more compression than you have now.
And with the way the SNS Stg 2 is designed, I think you'd probably want a little less compression since it's a 227 on a 107 ICL. You're going to be pushing the ragged edge for 93 with it at 59cc... especially with a .044" quench area. That's around 9:1 DCR.
I'd run it at 62cc with a Cometic .045" or 63 with a Cometic .040". Both would drop your compression down, improve your quench, and give you a little more clearance. All good things for improving power and reliability.
And with the way the SNS Stg 2 is designed, I think you'd probably want a little less compression since it's a 227 on a 107 ICL. You're going to be pushing the ragged edge for 93 with it at 59cc... especially with a .044" quench area. That's around 9:1 DCR.
I'd run it at 62cc with a Cometic .045" or 63 with a Cometic .040". Both would drop your compression down, improve your quench, and give you a little more clearance. All good things for improving power and reliability.
04-02-2013, 08:05 AM
#5
Well, you'd lose around .3 points of compression and gain a hair over .010" of clearance. What would that do to your power? You might lose 5-7rwtq and a few ponies for a little bit more clearance. The thing to remember is you are going to have a lot more compression than you have now.
And with the way the SNS Stg 2 is designed, I think you'd probably want a little less compression since it's a 227 on a 107 ICL. You're going to be pushing the ragged edge for 93 with it at 59cc... especially with a .044" quench area. That's around 9:1 DCR.
I'd run it at 62cc with a Cometic .045" or 63 with a Cometic .040". Both would drop your compression down, improve your quench, and give you a little more clearance. All good things for improving power and reliability.
And with the way the SNS Stg 2 is designed, I think you'd probably want a little less compression since it's a 227 on a 107 ICL. You're going to be pushing the ragged edge for 93 with it at 59cc... especially with a .044" quench area. That's around 9:1 DCR.
I'd run it at 62cc with a Cometic .045" or 63 with a Cometic .040". Both would drop your compression down, improve your quench, and give you a little more clearance. All good things for improving power and reliability.
Phil just e-mailed me back and said that at 60 to 60.5cc would put me right at 11:1. Any idea what 61cc would put me at?
Last edited by Rise of the Phoenix; 04-02-2013 at 08:18 AM.
04-02-2013, 09:40 AM
#7
Thank you JakeFusion!!! I had e-mailed Phil yesterday because he asked me what PTV clearance window I wanted and I told him that I didn't want any less than .060" on the intake and that is when he replied back with either 60cc or 60.5cc. So, it looks like I'll go with 60.5cc and use the OE gaskets I have. That will put me right at 11:1 compression. Do you know what my DCR will be?
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04-02-2013, 12:02 PM
#9
That figure you're coming up with is assuming the heads are milled to 61cc or 60.5cc? I really appreciate your help. I know I'm asking you a lot of questions, but I want to make sure I have everything lined up before I make the purchase.
04-02-2013, 06:20 PM
#14
Yeah, I know it's less than text book. I'm in a tough place because I want to run high compression for the added torque and power, but don't want to flycut the pistons. I think if I went with 61cc or even 62cc, that would give me a hair over .060 intake clearance, which would be a little safer. I'd love to hear other opinions.
You would be better off getting a thinner head gasket and milling the heads less.
Run a .040 gasket and mill your heads accordingly to get desired compression ratio.
This will run your quench tighter giving you more power on less compression.
For instance, say you're shooting for 11.5 static and you can get that with stock thickness (.052) gaskets and 59cc chambers, and your quench is at .047. Cool right? Well now you're at .050 intake ptv. Not cool.
Now, let's say you run a .040 gasket with a 62cc chamber. Now you're sitting at 11.25 static. Ok, a little less...but
What you gained in quench makes up for the loss of static compression, and you can run a little hotter tune and ultimately gain more power.
Here's where the ptv comes into play...
You went to a thinner head gasket by .012, but you kept about .020 on the head by not milling so much thus gaining you about .008 of ptv clearance for .058 of intake clearance. Which is still not optimal, but better.
I didn't get my calculators out so these numbers are just theoretical, but you now have another option and understanding on how you can keep the valves out of the pistons and still make the same power.
04-03-2013, 08:54 AM
#17
I do understand what you guys are saying, but I've already got the head gaskets, so that is what I"m going to use. I placed my order yesterday for the AI Dart/RHS 223cc heads, which will be milled to 60.5cc. I think these heads are going to work great with my Tick cam. I've seen so many great results out of A.I.'s 226cc and 232cc 234/799 heads and based on what Phil said, these A.I. Dart/RHS heads should be about 10 hp better than their ported 243/799 heads.
04-03-2013, 11:52 AM
#18
It'll be fine. You may have to pull timing due to the added compression and less than ideal quench to avoid KR.
One thing I've noticed is when you optimize the quench, you actually need less timing to make power. You get a more complete burn with less advance in the spark. So it ends up being safer and more powerful.
One thing I've noticed is when you optimize the quench, you actually need less timing to make power. You get a more complete burn with less advance in the spark. So it ends up being safer and more powerful.
04-03-2013, 11:59 AM
#19
It'll be fine. You may have to pull timing due to the added compression and less than ideal quench to avoid KR.
One thing I've noticed is when you optimize the quench, you actually need less timing to make power. You get a more complete burn with less advance in the spark. So it ends up being safer and more powerful.
One thing I've noticed is when you optimize the quench, you actually need less timing to make power. You get a more complete burn with less advance in the spark. So it ends up being safer and more powerful.