Looking for input on AC choices for M8 larger build engines with displacement of 120" and up, with ported heads and larger throttle bodies. Stage I AC is not going to cut it.

One's I've heard recommended are:

• Trask Assualt
• SE Heavy Breather
• T-Man No Loss
• Ness Big Sucker (may not flow as others)
• S&S Stealth

Any other ones I'm missing?



The Trask is nice, but expensive and I'm not crazy about the clear look.

 

Zippers has one & it's reasonably priced, I think it,s $159.95. FuelMoto is coming out with one, don't know anything about it, but should be pretty good, they also modified the HB, stock it pulls good Tq on stg 1 & 2 builds but doesn't flow as well as the TC HB. I'm going to use a Ventilator M8 backing plate with a TC filter since the stock M8 filter is about 40% smaller. It will take a little modification, drill 2 new holes & plug 3 original holes & use a couple of spacers. Should be good enough for a stg 1 or 2 when I get that far.

 

I have had great results with the S&S stealth....... the vortex design on the backing plate just seems to work.... I currently have it on a very stout twin cam build, have used it on a couple of others, and currently have one happily feeding my '17 M8...... plenty of cover options to suit your tastes as well..... DW

 

Have you run external breathers on the Stealth and if so, how'd you do it? Looks like they made the backing plate out of plastic?

 

The backing plate is plastic, as is the cover. The breather holes have an insert in them so if you are very careful you MAY be able to drill and tap it.

 

I have been told by a few this flows better than the M8 Heavy Breather. Its one of the better ones available at this point for the M8.

https://www.harley-davidson.com/stor...ow-air-cleaner

 

My indy is running the S&S and making mid 130s on his 120. He wants to try my HD intake but thinks it will be close to the S&S.

 

Yeah that's what I'm concerned about. The older ones were metal, but for some reason they went with plastic for the M8. Perhaps because the stock M8 manifold is plastic, I don't know.

I know the insert could be tapped. Then I wonder about blocking off the internal passage since again its plastic.

 

Is your indy running external breathers?

The S&S has that vortex directional thing that may help a little with the M8. The M8 manifold is offset to the right making the air horn close to the right edge of the filter, which makes for a tight right-hand turn for the air to flow.

I am considering both the SE Extreme and the S&S for now. Really not sure. The SE can be externally vented easier than the S&S from what I can tell.

 

From my experience there are minor gains in the above 5500-6000 rpms from using a wide open intake but the gain is not worth the money, effort, and less filtration quality.
The old design heavy breather (large) worked really well. The new, smaller unit, not as good.
The standby S/E air cleaner works to 5500 rpm on big builds.
In other words, you can get a couple more hp/tq without an a/f or huge, free breathing filter but really isn’t worth it unless you are racing and need that extra couple over 5000 rpm.
Just what I’ve seen over the years,
Bob