K&N Substack

[Sam]

Has anyone had any experience with the K&N substack that fits into the throat of a carb( http://www.knfilters.com/Racing/stubstacks.htm). In theory it is supposed to even out the air flow as it gets sucked into the carb. They claim modest gains in the range of 20-40 cfm which might give you another 8-20 hp depending how the carb is jetted............any thouhgts or is this just another whitches brew :toiletpap .

[tmdog]

I have a stubstack in the attic, never used. If a k&n filter and housing is used, I see no need for a stubstack. The k&n housing has a smooth taper on it's base so as to smooth the flow of air into the carb. If other kind of housing is used it may be beneficial to some extent. Is it witchcraft? It's your call.

[Schnook]

I vote witches brew. You could always go buy one of those "tornado" spacers to put under your carb to create a vortex out of the air you just straightened. I thought turbulence was desirable because it promotes a more even air/fuel mixture, but that may only apply to the intake manifold.

[MOP]

Yes the inner lip up at the filter is nice but the top of the carb has many irregularities, if this thing fits real well it allows the air to flow undisturbed past those irregularities. I feel where it does comes into play is at higher RPM's then we twist our boats.

Phil

[Sam]

MOP is right, that's where this thingy is designed to sit and do it's thing.

[MOP]

I have been looking into carb spacers which can add torque on some engines, I picked up a 1" aluminum one but was told I would be better off with a phenolic one to keep some heat away from the carb. I would like to figure out a way to supply cooler outside air without going to a scoop, though if I could find a decent looking one I might go with it. Rootsy had mentioned running a boat without the hatch to see if it increased speed, I may give that a shot come spring to see if it does helps mine out.

Phil

[BUIZILLA]

depending on the air filter and base arrangement, carb inlet config, and booster location, it's very possibly not witches brew...

[Moody Blu']

thats a must get on my list, im all about those extra rpm's. they say that helps air flow around the choke horn. I took all my choke parts off to increase airflow so this should help even more. according to the dyno test from hot rod mag, same motor with a K&N filter AND substack gained 10 hp. Hmmmm, I wonder how much power it gained with just the k&n filter?? I will still get it and test to see if it helps.

I did back to back tests without and with the 1" trans dapt swirl torque spacer. I gained 100-150 rpm's and had better throttle response all around.

http://store.summitracing.com/default.asp?target=egnsearch.asp&N=400158+308703+115&autoview=sku

[MOP]

Not sure where I picked this tid bit up but it is very important to make sure that any under carb adaptor or spacer be the exact size of the carb bores, any lip whether it hits it or come over it will disturb flow and will not give good results may actually hurt. Its just like port matching!

Phil

[tmdog]

Not sure where I picked this tid bit up but it is very important to make sure that any under carb adaptor or spacer be the exact size of the carb bores, any lip whether it hits it or come over it will disturb flow and will not give good results may actually hurt. Its just like port matching!
Phil

Good post. I run a 1 in. Wilson spacer and never did bother to check. Will check soon , taking upper part and replacing w/ other goodies. I know, more money for that elusive speed.:shocking:

[Sam]

Tmdog, goodies ? you can do better than that, didn't your mother tell you that it was not nice to tease :rlol: .

Sam :wavey: