Porting stock M8 heads v. SE CNC

[SoZo]

Just to be explicitly clear...

1. I do not want to name names but ALL yes ALL builders are having problems with the SE cylinders with a 4.180 bore....
2. I am sticking up for the machinist (who only did my heads actually) because he is not at fault.
3. TC 107 kit is even thinner then my skirt and they do not have problems.
4. The decision on the cylinder falls on me...

John

[1FSTRK]

Just to be explicitly clear...

1. I do not want to name names but ALL yes ALL builders are having problems with the SE cylinders with a 4.180 bore....
2. I am sticking up for the machinist (who only did my heads actually) because he is not at fault.
3. TC 107 kit is even thinner then my skirt and they do not have problems.

John

I have not seen any other postings about the SE cylinders, where did you see this?

I see nothing to blame anything on at this point, there was a post asking about the other damage in your engine, is the crank still good?

[HD/Wrench]

Look around you will see on this very site where a cylinder was cracked . it was a re-post but it was here. On others a few pics have been posted as well .

[1FSTRK]

Look around you will see on this very site where a cylinder was cracked . it was a re-post but it was here. On others a few pics have been posted as well .

What, where, when, links?

Added
I did find this thread it is about the 107 cylinders not the SE cylinders.
http://harleytechtalk.com/htt/index.php?topic=100529.msg1178556#msg1178556

There may be a learning curve for the aftermarket on these M-8 when trying to do things that worked on the twin cam. Has anyone checked the case deck height to wristpin height at BDC and compared that to a twin cam? Looks like the M-8 is pulling the entire piston into the spigot except for the ring pack. This may not allow running spigots as thin as we have seen on other engines.

While I agree I would not want a sharp point on the bottom of the spigot, I think that is a red herring as to the cause of the cracking.

[Nastytls]

I wasn't trying to cast blame on anyone, I didn't think it came off that way.  I just don't understand the order in which your problems happened.

Your first post listed all the upgrades you made, including cams and lifters. You then posted later along with a picture of a cracked cylinder that your crank seized and the "stock lifters and cams" went bad. Was it a new crank in the 121" build or was it the original? When did it seize?

[Dave I.]

http://headhoggersllc.com/m8-issue-update/

You guys ever see this?

[Ohio HD]

Yep

http://harleytechtalk.com/htt/index.php?topic=100529.msg1178556#msg1178556

[1FSTRK]

And back to the OP subject we have another set of SE heads out performing the ported bigger flow heads with yet another brand cam.

3-B
http://harleytechtalk.com/htt/index.php?topic=102988.msg1215993#msg1215993

After reading about a 148 S&S engine in the dyno section I did some research on the 143ci crate engines which took me back to part of the OP here about the size and flow of the OEM casting and the need to enlarge them and add flow to feed M-8 engines.

At the time of the OP we were looking at stock and test M8's ranging from 107ci to 120ci and most dyno test engines were 114ci kits. Most that are cnc porting the OEM casting are reporting numbers from 380-395 cfm as delivered to the customer. The S&S T143 is delivering 162-172hp depending on intake, exhaust, and tune from it's cnc heads flowing 358 cfm which is .466 hp/cfm this is what brings me right back to the OP here.

How much air can a 107 - 114 M8 use? How fast would you have to spin it to pump that air if it could? You can see the math here makes little sense.

[jbroski]

While sitting on the toilet. I solved the broken sleeve problem

[sfmichael]

well done sir 

[Eccool]

Dan Baisley said that the SE heads hardly flow any better than the stock heads.

[1FSTRK]

Dan Baisley said that the SE heads hardly flow any better than the stock heads.

But hardly better is still better and through smaller ports means not just better, faster.

[Don D]

I hear what you are saying and get the point. But at the end of the day even on the small (relatively) 107 there is no shortage of torque with the proper cam choice. And with all of the jockying of flow numbers there doesn't seem to be any big shifts in horsepower or torque from what I have observed.  Eric you follow these dynos close and would be able to see the trends better than I however. So the thread was about the SE heads being worthwhile?  Have we proven or is there any data to answer this?

[Eccool]

Dan Baisley said that the SE heads hardly flow any better than the stock heads.

I understand the importance of velocity, but for $1,400 (full retail on the SE CNC heads), I want more than a little improvement in flow.

[Don D]

I hear you!
But what does this improvement in flow buy when the flow potential exceeds the demand?
I am in development now on the heads so no public comments at this time until I get some testing done but based on what I am seeing there are still a lot of questions to be answered.

"Most of us being engine guys knows that an open barn door will move tremendous amounts of atmosphere but will not make horsepower. The same goes for drawing air through heads. The head must be correctly sized for the job with the straightest possible path to the back of the valve from the beginning of the intake tract.  I feel that providing approximate power figures and rpm range is a good indicator of potential."
From Greg Dahl

[1FSTRK]

I hear what you are saying and get the point. But at the end of the day even on the small (relatively) 107 there is no shortage of torque with the proper cam choice. And with all of the jockying of flow numbers there doesn't seem to be any big shifts in horsepower or torque from what I have observed.  Eric you follow these dynos close and would be able to see the trends better than I however. So the thread was about the SE heads being worthwhile?  Have we proven or is there any data to answer this?

I read the OP as being about if ported stock heads were meeting or exceeding the power level of the SE head and if it ever could, would it be at a cost that made it worth it.

Either way there is nowhere near enough quality data from either side to be definitive. Nobody has put any real effort into making power with the SE heads, most testing is being done by those hoping to market their porting skills but even with the one sided efforts the available numbers have shown no power/efficiency advantage to porting the stock castings and that in a way is a trend. The engine will soon enter it's third year of production and with the tech equipment owned and operated by the aftermarket at an all time high this is the longest development period for any HD head improvements by the aftermarket.

[1FSTRK]

Dan Baisley said that the SE heads hardly flow any better than the stock heads.

But hardly better is still better and through smaller ports means not just better, faster.

I understand the importance of velocity, but for $1,400 (full retail on the SE CNC heads), I want more than a little improvement in flow.

But do you really, what if it meant more power over a longer rpm range even if there were no no cfm increase. We have seen that huge increases in cfm alone with these heads returned little to no increases in power. Are you buying more flow or do you want more power?

[BVHOG]

Argue all you want but my flow bench has a drum and an eddy current brake.

[1FSTRK]

Argue all you want but my flow bench has a drum and an eddy current brake.

No argument here, two sides presenting information on their theories and findings.
What has your drum and brake shown you on the subject?

[BVHOG]

Argue all you want but my flow bench has a drum and an eddy current brake.

No argument here, two sides presenting information on their theories and findings.
What has your drum and brake shown you on the subject?

Well over time it has shown me that flow is only "Potential" and that the Mil 8 bikes do not return as much dollar for dollar with headwork but I feel that will change with time.   The drum only shows "reality" of an entire combination however flawed that may be.    So to explain it I will tell you the story of a young boy asking his dad the difference between potential and reality. He first asked his wife if she would sleep with Trump for a million dollars and she said "of course"  he then asked his daughter if she would sleep with Trump for a million dollars and she said " hell yeah"  So he explained to his son that "Potentially" we are sitting on two million bucks, "Reality" is we are living with a couple of whores.

[KTA600]

Argue all you want but my flow bench has a drum and an eddy current brake.

No argument here, two sides presenting information on their theories and findings.
What has your drum and brake shown you on the subject?

Well over time it has shown me that flow is only "Potential" and that the Mil 8 bikes do not return as much dollar for dollar with headwork but I feel that will change with time.   The drum only shows "reality" of an entire combination however flawed that may be.    So to explain it I will tell you the story of a young boy asking his dad the difference between potential and reality. He first asked his wife if she would sleep with Trump for a million dollars and she said "of course"  he then asked his daughter if she would sleep with Trump for a million dollars and she said " hell yeah"  So he explained to his son that "Potentially" we are sitting on two million bucks, "Reality" is we are living with a couple of whores.

Lmfao....

[Rusty Steel]

"Well over time it has shown me that flow is only "Potential" and that the Mil 8 bikes do not return as much dollar for dollar with headwork but I feel that will change with time.   The drum only shows "reality" of an entire combination however flawed that may be.    So to explain it I will tell you the story of a young boy asking his dad the difference between potential and reality. He first asked his wife if she would sleep with Trump for a million dollars and she said "of course"  he then asked his daughter if she would sleep with Trump for a million dollars and she said " hell yeah"  So he explained to his son that "Potentially" we are sitting on two million bucks, "Reality" is we are living with a couple of whores."

Now that is funny... Made my day. Happy Friday the 13th!

[whtrthanu]

Gonna throw in my 2 cents here. Being im a new guy ill make it short.
  From what I have seen so far is this. The factory head keeps the valve size ratio smaller the ideal. What I see from that is the cd stays way up and port velocity as well. I would stay with stock size valve and adjust the seat id to cheat it. I would be the dyno that the hp numbers on the dyno would be close to a big valve head or less but the stock valve head would crush it on the road or track