The future of the M8

[Durwood]

Big cubes will be a must with ports and valves this big in the M8. After finally growing the twin cam big enough to use it's ports they appear to have gone back to their old math for the port and valve sizes for the 107ci M8.

The M8 as a stage 2 will be plenty for 90% of Harley performance enthusiasts IMO, some guys will be happy with a set of pipes and good tune.

The all in big cube crowd will be able to make serious power without breaking the bank on extensive head work.

[Hossamania]

at some point I hope they dump the stupid cam set up and go over head. Now we can start making better changes. The ability to control intake and ex separately  has been one of the largest improvements in over head cam engines . HD is holding onto the past. If you want power like others then well take a long hard look at what they are doing how and freaking successful it has been. IE victory those engines have very little failures and make big power 110/110 with a cam swap and slip on mufflers. Engines are smooth with very wide bands of usable power. I feel you are seeing a intermediate engine myself.

Look at what the new EPA is looking for, ( noise is also in the EPA ) The regs keep getting stiffer. The dual over head cams would be of huge help . I do not think we will see a "vanos" system anytime soon. That would be great but packaging  is a nightmare.  And HD is anything but up for spending huge money. "more so just enough to almost get the job done"

If HD could make a compact version of the 4 cam sportster valve train, we can have the separate intake from exhaust and keep the OHV with push rods. And I mean that for tradition sake. I think going OHV might be a negative to HD owners. The V-Rod was enough change that it just didn't sell.

I think the Vrod didn't sell because it was not a very attractive package.

[1FSTRK]

Big cubes will be a must with ports and valves this big in the M8. After finally growing the twin cam big enough to use it's ports they appear to have gone back to their old math for the port and valve sizes for the 107ci M8.

The M8 as a stage 2 will be plenty for 90% of Harley performance enthusiasts IMO, some guys will be happy with a set of pipes and good tune.

I agree here, I just do not think the stage 2 will be showing a great increase in hp/ci over a stage two Twin Cam.

The all in big cube crowd will be able to make serious power without breaking the bank on extensive head work.

I guess here is where we wait and see. Time will tell if the M-8 heads with their large ports and valves can turn large flow numbers into serious HP/CI on even large displacement engines. With flow numbers like  "325/235 @ 1/2" lift" for stock M-8 heads they are flowing as good or better then most ported Twin cam heads so a stock head M-8 with good cams should be making power more comparable to a Twin cam 107ci kit with ported heads and cams.

The single cam part does little for me from a performance stand point. The real change is the intake/exhaust tract and HP/CI over the rpm range will be the tell on how much of an improvement there will be.

[HD/Wrench]

well we have Axtell selling 4.125 pistons and stating bore the stock 107 to that point. Not to make fun but really ?? Brand new part and we know that there could be little to no real testing at this point so early in the game..  Maybe it works out or maybe it does not.. but to me that overly optimistic currently .. I guess we wait for the first dozen guinea pigs to see how it does .

If it works out that is great , simply way to get to 117 inch.

[1FSTRK]

well we have Axtell selling 4.125 pistons and stating bore the stock 107 to that point. Not to make fun but really ?? Brand new part and we know that there could be little to no real testing at this point so early in the game..  Maybe it works out or maybe it does not.. but to me that overly optimistic currently .. I guess we wait for the first dozen guinea pigs to see how it does .

If it works out that is great , simply way to get to 117 inch.

If indeed they checked liner thickness and found it to be comparable to other such practices it is reasonable to conclude it would work. The first 883s were bored to 1200s before the factory even released the 1100s. It  did not take long for the factory to follow and the 1200 is now the longest running cylinder the factory produces.

[Durwood]

Big cubes will be a must with ports and valves this big in the M8. After finally growing the twin cam big enough to use it's ports they appear to have gone back to their old math for the port and valve sizes for the 107ci M8.

The M8 as a stage 2 will be plenty for 90% of Harley performance enthusiasts IMO, some guys will be happy with a set of pipes and good tune.

I agree here, I just do not think the stage 2 will be showing a great increase in hp/ci over a stage two Twin Cam.

The all in big cube crowd will be able to make serious power without breaking the bank on extensive head work.

I guess here is where we wait and see. Time will tell if the M-8 heads with their large ports and valves can turn large flow numbers into serious HP/CI on even large displacement engines. With flow numbers like  "325/235 @ 1/2" lift" for stock M-8 heads they are flowing as good or better then most ported Twin cam heads so a stock head M-8 with good cams should be making power more comparable to a Twin cam 107ci kit with ported heads and cams.

The single cam part does little for me from a performance stand point. The real change is the intake/exhaust tract and HP/CI over the rpm range will be the tell on how much of an improvement there will be.

As product development continues I can see these 107's easily making comparable TQ/HP to a Twin cam with the added compression and appropriate camshaft profile.

[rbabos]

at some point I hope they dump the stupid cam set up and go over head. Now we can start making better changes. The ability to control intake and ex separately  has been one of the largest improvements in over head cam engines . HD is holding onto the past. If you want power like others then well take a long hard look at what they are doing how and freaking successful it has been. IE victory those engines have very little failures and make big power 110/110 with a cam swap and slip on mufflers. Engines are smooth with very wide bands of usable power. I feel you are seeing a intermediate engine myself.

Look at what the new EPA is looking for, ( noise is also in the EPA ) The regs keep getting stiffer. The dual over head cams would be of huge help . I do not think we will see a "vanos" system anytime soon. That would be great but packaging  is a nightmare.  And HD is anything but up for spending huge money. "more so just enough to almost get the job done"

If HD could make a compact version of the 4 cam sportster valve train, we can have the separate intake from exhaust and keep the OHV with push rods. And I mean that for tradition sake. I think going OHV might be a negative to HD owners. The V-Rod was enough change that it just didn't sell.

I think the Vrod didn't sell because it was not a very attractive package.

You calling my bike ugly. Actually what killed the vrod from the start was price and accessory support. Take a look at the Victory Octane. Almost a direct copy of the v rod but 5k less and already more accessories available.  They are selling. Piss poor marketing on HDs part when it came to the rod. It's almost like they never really wanted to sell them from the get go based on price alone, then followed up with next to no decent accessories. Basically a no brainer for that level of bike. Pay 17+k for a vrod that runs like "Potty mouth" on factory cal or 12k for the Octane that runs extremely nice on the factory cal that looks about the same, good quality and USA made. The equivilent HD Street is a joke in comparison. Another dud in my view.
Ron

[1FSTRK]

Big cubes will be a must with ports and valves this big in the M8. After finally growing the twin cam big enough to use it's ports they appear to have gone back to their old math for the port and valve sizes for the 107ci M8.

The M8 as a stage 2 will be plenty for 90% of Harley performance enthusiasts IMO, some guys will be happy with a set of pipes and good tune.

I agree here, I just do not think the stage 2 will be showing a great increase in hp/ci over a stage two Twin Cam.

The all in big cube crowd will be able to make serious power without breaking the bank on extensive head work.

I guess here is where we wait and see. Time will tell if the M-8 heads with their large ports and valves can turn large flow numbers into serious HP/CI on even large displacement engines. With flow numbers like  "325/235 @ 1/2" lift" for stock M-8 heads they are flowing as good or better then most ported Twin cam heads so a stock head M-8 with good cams should be making power more comparable to a Twin cam 107ci kit with ported heads and cams.

The single cam part does little for me from a performance stand point. The real change is the intake/exhaust tract and HP/CI over the rpm range will be the tell on how much of an improvement there will be.

As product development continues I can see these 107's easily making comparable TQ/HP to a Twin cam with the added compression and appropriate camshaft profile.

Taking a look at the stage 2 builds that are showing up in the dyno section and considering the higher compression the M-8 starts with you may start to see comparable but that does say that the new design does not excel in the hp/cfm department. From a discussion of design point of view I would think if the head were better because of the additional flow alone the dyno numbers would be far more impressive.   

[XL90R]

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[XL90R]

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[XL90R]

Plenty of good stuff going on with these new motors and twin cam guys are gonna be pretty sad when they realize the potential these motors have..
And the power delivery is much much better.. I have never been a fan of twin cam Motors, I think this was the right step forward for Harley, they will never be able to sell a dohc water cooled motor.. this is the best base line motor to work with yet IMO..


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[joe_lyons]

[1FSTRK]

Now you are getting closer to using the area of the ports and valves.

[XL90R]

Big cubes will be a must with ports and valves this big in the M8. After finally growing the twin cam big enough to use it's ports they appear to have gone back to their old math for the port and valve sizes for the 107ci M8.

The M8 as a stage 2 will be plenty for 90% of Harley performance enthusiasts IMO, some guys will be happy with a set of pipes and good tune.

I agree here, I just do not think the stage 2 will be showing a great increase in hp/ci over a stage two Twin Cam.

The all in big cube crowd will be able to make serious power without breaking the bank on extensive head work.

I guess here is where we wait and see. Time will tell if the M-8 heads with their large ports and valves can turn large flow numbers into serious HP/CI on even large displacement engines. With flow numbers like  "325/235 @ 1/2" lift" for stock M-8 heads they are flowing as good or better then most ported Twin cam heads so a stock head M-8 with good cams should be making power more comparable to a Twin cam 107ci kit with ported heads and cams.

The single cam part does little for me from a performance stand point. The real change is the intake/exhaust tract and HP/CI over the rpm range will be the tell on how much of an improvement there will be.

As product development continues I can see these 107's easily making comparable TQ/HP to a Twin cam with the added compression and appropriate camshaft profile.

Here is a comparison of a bone stock 107 vs a 107 with SE hp cam and slip ons with no tuning.

This is the M8 with bassani 2:1, high flow filter and a power vision dyno tune..(85hp 110 tq) Throw a hp cam in and hp jumps to mid 90s. I'd say it's quite a bit better.






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[XL90R]

110tq @ 2700 rpms.. Now that's a good time

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[1FSTRK]

110tq @ 2700 rpms.. Now that's a good time

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First I would like to welcome you to HTT.

I do not think anyone is saying the M-8 does not run well in stock form or even that it does not benefit nicely from a stage two and a good tune. I am looking at the thread title from a performance/tech point of view.
In the Harley world it has always been a simple task to gain power by having the heads ported because they lacked adequate flow to feed the stock displacement from the factory. The M-8 comes with heads that have flow numbers that surpass those of most ported twin cam heads on the market. My point is speaking from a flow numbers or HP/CFM standpoint, if the head design is as good as the flow numbers a properly setup M-8 with cams and stock heads should be out performing the ported Twin Cam kits or these heads are not really an improvement. Another thing to look at will be what happens to the power when people hog out the ports to get even bigger flow numbers. Yes the power will go up but will they give up tq in the lower rpm range, will the power go up proportionally to the flow increase? If you look in the dyno section here you will see the M-8 graphs posted to date do not accurately reflect the amount of air these stock heads flow even when the bigger bore kits are added.

I am thinking the future will show that larger TB's will help to get hp/ci numbers as well as hp/cfm numbers closer to the level of the ported Evo and Twin cam designs but as I said above it will take more to show a legitimate improvement of the 4 valve head over the 2 valve heads and call the job HD did on these a success.

[XL90R]

110tq @ 2700 rpms.. Now that's a good time

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First I would like to welcome you to HTT.

I do not think anyone is saying the M-8 does not run well in stock form or even that it does not benefit nicely from a stage two and a good tune. I am looking at the thread title from a performance/tech point of view.
In the Harley world it has always been a simple task to gain power by having the heads ported because they lacked adequate flow to feed the stock displacement from the factory. The M-8 comes with heads that have flow numbers that surpass those of most ported twin cam heads on the market. My point is speaking from a flow numbers or HP/CFM standpoint, if the head design is as good as the flow numbers a properly setup M-8 with cams and stock heads should be out performing the ported Twin Cam kits or these heads are not really an improvement. Another thing to look at will be what happens to the power when people hog out the ports to get even bigger flow numbers. Yes the power will go up but will they give up tq in the lower rpm range, will the power go up proportionally to the flow increase? If you look in the dyno section here you will see the M-8 graphs posted to date do not accurately reflect the amount of air these stock heads flow even when the bigger bore kits are added.

I am thinking the future will show that larger TB's will help to get hp/ci numbers as well as hp/cfm numbers closer to the level of the ported Evo and Twin cam designs but as I said above it will take more to show a legitimate improvement of the 4 valve head over the 2 valve heads and call the job HD did on these a success.

I understand ya, and as someone Stated earlier in post I think the m8 how it stands will be satisfying for most the "typical" Harley riders.. For us other 10%
Nothing Harley sells in their motors stays stock anyhow.. Hell my 90" sportster puts out about the same power and very close tq to a built Twinkie 107.. I think given some time this new motor with the right internals will perform very well.. In its stock form it's" good enough" to appease the avg rider, and be a much more enjoyable ride over the TC.. I'm more hoping this new motor won't have all the same weak points the TC motor has in design.. Guess time will tell.
Thanks for the welcome btw!!


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[joe_lyons]

I hope that there is more than 10% out there.

[XL90R]

I hope that there is more than 10% out there.

Probably are, but that other % probably running SE internals lol.


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[HD/Wrench]

well we have Axtell selling 4.125 pistons and stating bore the stock 107 to that point. Not to make fun but really ?? Brand new part and we know that there could be little to no real testing at this point so early in the game..  Maybe it works out or maybe it does not.. but to me that overly optimistic currently .. I guess we wait for the first dozen guinea pigs to see how it does .

If it works out that is great , simply way to get to 117 inch.

I do not disagree, however until you get a fair amount of them out there and real miles on them.. When we did our first 98 inch kit due to failure with the Rev product. we had 5 of them running for close to 10 months before we released the kits and it did require a piston swap due to a ring issue. Now we where told that would not work. I understand that you can measure something and say well its been done before. but each new step in my opinion requires testing.  What testing has been done yet??

for that fact we still have no idea what we are in for as far as crank failures, new oil pump failures, rocker arm issues .. Not bashing it just stating I think that the view point needs to be widened a fair amount. No real miles on them yet and I rode with one to AK and it had some issues oil usage wise. They did repair it,  with a new engine.  He only has 1500 miles on the new one and thus far not using oil like the first one. But we all know all things can fail. 

as for the future of the M8 It will see some more changes without a doubt. Not sure I will ever own one but then again I am waiting on the new BMW bagger 

If indeed they checked liner thickness and found it to be comparable to other such practices it is reasonable to conclude it would work. The first 883s were bored to 1200s before the factory even released the 1100s. It  did not take long for the factory to follow and the 1200 is now the longest running cylinder the factory produces.

[Don D]

The larger head bolt pattern opens up possibilities. Maybe a 3/8 stroke 124? The heads have the overhead to go big. Valve control at higher rpm seems possible but testing will reveal more. We have given the 107 TC all  the head it can use and more and the results are well documented. Now we have new possibilities. If these motors will remain stable at 7-7500 rpm (~5500fpm) in a street configuration that is real exciting to me. Strong light pistons will extend the life.
Lots to look forward to.

[1FSTRK]

The larger head bolt pattern opens up possibilities. Maybe a 3/8 stroke 124? The heads have the overhead to go big. Valve control at higher rpm seems possible but testing will reveal more. We have given the 107 TC all  the head it can use and more and the results are well documented. Now we have new possibilities. If these motors will remain stable at 7-7500 rpm (~5500fpm) in a street configuration that is real exciting to me. Strong light pistons will extend the life.
Lots to look forward to.

Could you explain why?

[Don D]

Not really because I have not had a set of these heads in my hands yet.
It would depend on components weight, spring pressure required to get the job done, and perhaps less aggressive cam profiles could be employed. Spintron testing.

We are pushing the TC lifters now with the heavy components and spring pressures plus aggressive cam profiles.
What are your ideas relating to this?

[1FSTRK]

More valve weight, more retainer/keeper weight, more rocker weight (particularly away from center where it counts the most), more valve to guide surface area, and still running pushrods. I agree that flow will be achieved at lower lifts but without doing the math as you say, it seems a wash to me. It may show slightly better numbers in the math but I definitely would go as far as to say no appreciable gains through higher rpm due to valve train advancements.


 

[Don D]

I see your point, I may have been overly optimistic. Thanks