M8 power output

[08flstf]

So, any more comments or new info on M8 power output? That was the title of this thread right?

[vincer77]

I'm seeing some of these dyno runs from the 117" M8 making a little under 125 hp/tq with 11:1 compression. I'm making pretty the same power with my Twin Cam with the bolt on 110 cylinders and basic head work, Tman 577 cams and less compression. I doubt my heads flow as well as the 4 valve head. Kind of wonder why we're not seeing the M8 making more power.

No one is making large improvements with the M-8 over the Twin cam when it comes to HP/CI or HP/CFM. The the over all intake design as delivered from HD just is not that great. Many mistakenly believe that 50 percent more air flow was all that was needed. I also do not think two valves, two springs sets, and a bigger rockers weight less than the single valve twin cam setup. All that load is now on the same old C lifter that was no good in the twin cam.

The potential is there... The current intake and exhaust offerings are not capable of flowing what the heads can flow. The heads with professional expert porting (CNC Heads flow almost NO better then stock)  with stock valve sizes can make big improvements in the exhaust port and good gains in the intake. Larger valves make big strides... Cam profile is totally different, overlap needs to start at 100mm lift to get things flowing. There is no Borizilla size exhaust yet.. Fuel Moto is working on large stepped 2 into 1 which will greatly enhance exhaust savaging and HP capability.  The screeming Eagle Throttle Body and intake have a bad design where one cylinder flows 55cfm less the the other(I forget front or rear){the SE intake can be worked by porting to flow more} HP INC has a better 62mm setup which flows substantially more. ALSO there are not many high compression pistons out yet... most are flat top @10.5:1.

Burns Stainless already makes two big pipes for M8s and have seen 131 builds near 180hp.  Check out Star Racing.

[sandrooney]

So far I like my 18 Heritage 114. Can't wait to pipe it and tune it. Just don't want to mess up the warranty or I already would have.

[sfmichael]

So far I like my 18 Heritage 114. Can't wait to pipe it and tune it. Just don't want to mess up the warranty or I already would have.

you can probably do that with HD stuff and retain the warranty

[sandrooney]

I am sure I can but the Harley slip on's will still have the cats in the mufflers and not really be that much different in sound or feel.
I wonder if I could go with some V&H and use the Harley tuner and still retain the warranty?
Thanks
SR

[Nastytls]

I am sure I can but the Harley slip on's will still have the cats in the mufflers and not really be that much different in sound or feel.
I wonder if I could go with some V&H and use the Harley tuner and still retain the warranty?
Thanks
SR

No you can't, unless you put the stock pipes back on before bringing it in for service you could.

[IronButt70]

I am sure I can but the Harley slip on's will still have the cats in the mufflers and not really be that much different in sound or feel.
I wonder if I could go with some V&H and use the Harley tuner and still retain the warranty?
Thanks
SR

No you can't, unless you put the stock pipes back on before bringing it in for service you could.

That can also depend on the dealer.

[sfmichael]

I am sure I can but the Harley slip on's will still have the cats in the mufflers and not really be that much different in sound or feel.
I wonder if I could go with some V&H and use the Harley tuner and still retain the warranty?
Thanks
SR

No you can't, unless you put the stock pipes back on before bringing it in for service you could.

A lot depends on the dealer...SR has bought several bikes from the same people and if I were them I would do it for him. Anyone in their right mind knows some exhaust and a performance map isn't going to hurt anything, and some people still have common sense. I don't know about a long journey out of state if one had to depend on another dealer - that may be tricky.
The whole warranty / EPA thing has gotten out of hand and I find it ridiculous. Doesn't matter what I think, I certainly know that. But dealers have been bending the rules in certain circumstances for years and I'm sure some will continue to do so.
FWIW my 2 of my 4 new bikes never had a warranty concern, and none ever had an engine related issue.

[Nastytls]

I am sure I can but the Harley slip on's will still have the cats in the mufflers and not really be that much different in sound or feel.
I wonder if I could go with some V&H and use the Harley tuner and still retain the warranty?
Thanks
SR

No you can't, unless you put the stock pipes back on before bringing it in for service you could.

That can also depend on the dealer.

Yes, you are correct. I was making a general statement regarding how HD is currently looking at things.

There are good dealers out there that won't f**k their customers and others that will. If I had to guess there are more that will vs. won't. My dealer knows what I have done to my M8 and are not reporting me to HD.

[sandrooney]

Will the super tuner adjust enough for the V&N 300 eliminator slip on's ?  I read it doesn't adjust for fuel.

[1FSTRK]

Will the super tuner adjust enough for the V&N 300 eliminator slip on's ?  I read it doesn't adjust for fuel.

It will adjust the fuel but no matter what it still adjusts to the very lean EPA air fuel ratios that are locked in.
This is a problem with stock power and more so when you open up the air in and air out because with more air and fuel you get even more heat at that same lean AFR. None of this adjusts the extreme timing numbers and when the heat goes up you will get even more detonation.
Will it keep the warranty and last until it expires, you bet, but when that warranty is up you own the POS and the damage is done then you fix it on your dime.

[sandrooney]

I have the 114 so it already has the hi flow A/C. I don't know if the map is different than the stock 107. It runs great and in no way do I feel the heat like I did on my TC. No detonation at all. I got no detonation on my TC either (Rushmore 103 box stock except for Street Cannons). My only concern with the warranty is the issues some M8's are having. I have not read about these issues on the softail so maybe I don't need to be so concerned. Do I roll the dice or not is the question?
Thanks

[DTTJGlide]

S&S has a set of slip ons with a hi flow cat that are EPA compliant, they have a sound clip on the billet tip model, they also have a slash cut for $449.95, they don't sound too bad, might be another option.

[sandrooney]

I'll take a look at them. Thanks

[hattitude]

I'm seeing some of these dyno runs from the 117" M8 making a little under 125 hp/tq with 11:1 compression. I'm making pretty the same power with my Twin Cam with the bolt on 110 cylinders and basic head work, Tman 577 cams and less compression. I doubt my heads flow as well as the 4 valve head. Kind of wonder why we're not seeing the M8 making more power.

If you're willing to go aftermarket, and warranty be damned (or expired) there are some shops making good power from the M8.. but of course, they are making big bore kits...

Fuel Moto is working on 124 Milwaukee Eight big bore kits, and show a dyno chart, reporting a max torque of 159.30