Stupid exhaust question

[midmoraider]

Hey all, was wondering if our bikes make better numbers with a dual or single exhuast setup. Or does it really matter? Thanks.

 

[[email protected]]

Doesn't make enough difference to worry about.

 

[Rusty McNeil]

I think a 4-1 versus 4-2 comparison theoritically has one making slightly more top end HP and one making better mid range torque..Don;t remember which is which..In the real world I don't think it amounts to enough to worry about either way; Making esthetics the "choosing" factor....

 

[Thevmaxrider]

A true 4-1 will make better top end hp, but they tend to suffer from a loss of mid-range power. A 4-2-1 makes slightly less hp than the 4-1 and smooths out the curve and eliminates the flatspot in the mid-range. A 4-2 has lower high end hp and good mid-range. A 4-2 with a crossover between the rear headers (i.e. Marks system) Has slightly better top end hp and mid-range power than a 4-2 without the cross over and not quite as much as a 4-2-1 at the top. The main difference seems to me to be the length of the rear headers by comparison between the various systems.

Confused yet?

 

[tugla]

so jim it goes

4-2, 4-2 with cross over, 4-2-1 then 4-1...... is that how you would put it or move the 4-2 with cross over up a spot???

not confused until i wrote it down hahaha

 

[[email protected]]

Confused yet?

Sounds correct to me Jim.

I'd be guessing when I say that on a stock engine vmax, install a jet kit, and install a good aftermarket header of any design and I doubt you would see more than a few HP difference between one pipe or the other with everything else being equal.

Add in compression, large bore, stroke, cam, etc.... and I think pipe selection would become more of a factor and you would see a larger difference in HP between designs.

 

[Thevmaxrider]

Sounds correct to me Jim.

I'd be guessing when I say that on a stock engine vmax, install a jet kit, and install a good aftermarket header of any design and I doubt you would see more than a few HP difference between one pipe or the other with everything else being equal.

Add in compression, large bore, stroke, cam, etc.... and I think pipe selection would become more of a factor and you would see a larger difference in HP between designs.

Absolutely correct! On a stock displacement engine with a jet kit there might be a 2-3hp difference between them. As the displacement goes up that changes quite a bit. Know that with a 4-2 Toxic made almost 10hp less than with a 4-1. Exhaust scavenging gets very important as you start to up the displacement/hp numbers.

 

[Thevmaxrider]

so jim it goes

4-2, 4-2 with cross over, 4-2-1 then 4-1...... is that how you would put it or move the 4-2 with cross over up a spot???

not confused until i wrote it down hahaha

Looks correct to me, although without a dyno, and even with one, I would be willing to bet that the 4-2 w/cross over pipe and the 4-2-1 would be damn close. Between those two it comes down to looks IMHO.

You also have to take into account exhaust can outlet size, header size, header lengths (are they all equal or not), etc. I really like the Hindle 4-2-1 on Toxic, but Lang Hindle has said that the header tubes are too small and I need a custom stepped exhaust to really let my engine breathe. He figures a bolt on 10hp or so just by doing that. Now to come up with the $$$$$$$ to get it done!!!

 

[MagnaVMax]

Not a dumb question. I actually had been wandering the same thing. Thanks for asking.

 

[Rollie]

Sean , chime in please . :clapping:

 

[Thevmaxrider]

Sean , chime in please . :clapping:

What???? Don't trust my experience????? LOL!!!! Just messing! I can say I have had stock, 4-2, 4-1, and now 4-2-1 and they all have their charm. For the average rider exhaust is about look and sound rather than performance.

 

[Rollie]

What???? Don't trust my experience????? LOL!!!! Just messing! I can say I have had stock, 4-2, 4-1, and now 4-2-1 and they all have their charm. For the average rider exhaust is about look and sound rather than performance.

Yes I do trust your experience with exhausts. I wanted Sean to chime in and confirm what you had found , as he was , ( at one time ) , conducting a series of dyno runs with different exhaust set ups , and I thought it would be a good time to compare your findings with his. I have tried a few myself and agree the average maxer , ( myself included ) , will not be able to tell 3-9 h.p. difference by the seat of the pants testing . I think there will be few true aftermarket performance exhausts giving more than that from a mostly stock motor.

 

[Thevmaxrider]

I agree 100%. Didn't know Sean was doing dyno testing on different exhausts, although I know he did a ton while developing his jet kit. Just putting an exhaust on an otherwise stock Vmax will only get you 1-3hp at best. Sean's kit is another 7-9hp. This is why an otherwise stock Vmax with Sean's kit and a full exhaust system will make ~125 RwHP give or take a bit. A stock Vmax will be 110-115 Rwhp out of the box usually. Will the average rider note 10hp more, maybe a bit, but to really notice you need to go up in displacement and do some other mods before you notice big jumps in hp. In all honesty I would bet that if folks did the DD mod to their clutch they would note better performance before they would with an exhaust. Of course this is all just my opinion.

 

[MR_NST]

lol, the dd mod has its place, not in my bike. i had it and abused it. tore out 2nd gear. the bike definatly felt like it was touchier, like it was sure of the power to the ground. did you know the vmax can very assuredly power wheelie second at 40 mph with a 250 lb guy on it. news to me, but sure was fun. sean was a huge help in the rebuild so i figured back (somewhat) to stock. its cheaper to replace the clutch than the trans. sorry for the hijack

ive never experimented with different sets of pipes but the jet kit and marks 4 - 2 was a nice shot in the pants when i first opened her up.

peace,
evan...