Another Cam Question
Intermediate
Joined: Oct 2009
Posts: 44
Likes: 0
From: KL Malaysia
Depending on your cyl deck height, you should be around 9.1 corrected compression with 79cc heads, .030 head gaskets and the TW6. Try a HQ-0034, that should put your corrected compression to about 9.3 and help your bottom end.
Thread Starter
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Road Warrior
Joined: Jul 2011
Posts: 1,326
Likes: 333
From: Central TX
Not being argumentative either but question the logic. The assumption that two sets of heads, one the larger valves than the other, will flow the same is flawed logic. The laws of physics won't allow it.
I meant to say if you have two heads that flow similar cfm and one has smaller valves, the heads with smaller valves must be flowing at a higher velocity to achieve the same volume. I
I don't understand the 199CCP. I seriously doubt that the Ross piston has a positive dome volume but I could be wrong. The piston is a flat top, no dome, with valve reliefs. A six pack says that the dome volume is -2.5 to -3cc, so I am thinking something is missing from the data, or the pistons do actually have a positive dome volume which would be unusual for a flat top; it would be nice to know and I can't believe Ross doesn't know unless they are selling a piston manufactured by a third party and they have branded as their own.
The 199psi is what the ccp measured using a quality gauge. I wish I knew the actual dome volume, but the Ross tech could not provide any answer. What compression do flat top cylinders usually run? How do you get flat tops with different compression ratings if you aren't adding volume to the pistons? If I entered the dome volume you suggest, my static cr and ccp would be much less (184psi vs measured 199psi).
The sheet you posted is not that bad; good numbers up to .400" lift but from .400" to .600" I would expect better from a shop that specializes in Harley head porting; like numbers in the 260(intake)/220(exhaust) range.
I agree and like I said in earlier post, the heads were only setup for .510 lift cams, so not surprised they don't continue to build more flow at .600.
I still think your heads are the bottleneck to more power and a better curve. JMHO
I meant to say if you have two heads that flow similar cfm and one has smaller valves, the heads with smaller valves must be flowing at a higher velocity to achieve the same volume. I
I don't understand the 199CCP. I seriously doubt that the Ross piston has a positive dome volume but I could be wrong. The piston is a flat top, no dome, with valve reliefs. A six pack says that the dome volume is -2.5 to -3cc, so I am thinking something is missing from the data, or the pistons do actually have a positive dome volume which would be unusual for a flat top; it would be nice to know and I can't believe Ross doesn't know unless they are selling a piston manufactured by a third party and they have branded as their own.
The 199psi is what the ccp measured using a quality gauge. I wish I knew the actual dome volume, but the Ross tech could not provide any answer. What compression do flat top cylinders usually run? How do you get flat tops with different compression ratings if you aren't adding volume to the pistons? If I entered the dome volume you suggest, my static cr and ccp would be much less (184psi vs measured 199psi).
The sheet you posted is not that bad; good numbers up to .400" lift but from .400" to .600" I would expect better from a shop that specializes in Harley head porting; like numbers in the 260(intake)/220(exhaust) range.
I agree and like I said in earlier post, the heads were only setup for .510 lift cams, so not surprised they don't continue to build more flow at .600.
I still think your heads are the bottleneck to more power and a better curve. JMHO
Thread Starter
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Road Warrior
Joined: Jul 2011
Posts: 1,326
Likes: 333
From: Central TX
Really, at this point I want feedback on great cam for 95" with 9.9 - 10.1:1 cr? Leaning towards cr575, tw5, or Tman 555 Torqster. Never see any Dyno sheets for these on a B motor - everything is on touring bikes.
Tourer
Joined: Sep 2014
Posts: 420
Likes: 5
From: Kingsport, TN
The latest rage for those wanting low end torque and a decent powerband (~1800-5000 rpm) is Steve Cole's TTS100 cams. The tried-and-true standard for twincam torque cams is the Andrews 48.
Last edited by dynawg1; Apr 5, 2015 at 12:08 AM.
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Thread Starter
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Road Warrior
Joined: Jul 2011
Posts: 1,326
Likes: 333
From: Central TX
I have looked at a lot of cams, but never heard of the Coles cams. I will look them up - thanks. Originally, I did not think of 48's, but looked at them just yesterday, but read 10:1 compression might be too much. Any thoughts on max cr for 48's and how far up in rpm range these continue to pull?
Seasoned HDF Member
Joined: Mar 2010
Posts: 21,095
Likes: 7,622
From: Poolville
I have looked at a lot of cams, but never heard of the Coles cams. I will look them up - thanks. Originally, I did not think of 48's, but looked at them just yesterday, but read 10:1 compression might be too much. Any thoughts on max cr for 48's and how far up in rpm range these continue to pull?
When are you gonna tear your motor down and measure cylinders, deck clearance as well as base gasket. I see that Ross did make oversize pistons in that 9.4 setup. Did you build the motor (or assemble) or an indy? I think you should stop guessing and find out what you have down low. Might as well measure your stroke while you're at it. At least you'll know all for sure..and log it.