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Hey guys, I have a 400ex exhaust question... What would be the best exhaust for me, im looking for alot of bottom-end without scraficing alot of top-end. Also what jetting would i use with it, im at less that 500 feet above sea level...

Thanks,

- much2fear89
 

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pro curcuit :tup:
 

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white brothers carbon pro, only 799 bucks from motosport outlet, or if you cant afford that then get the E2, its awsome and comes with a spark arrester, you can take it out when you go to the track and put itback in for the woods with like one tool, pretty sweet stuff, youd have to buy your je kit i believe though, not a big deal
 

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Seems like your going to have to look around for more info cause all the pipes listed so far are way too free flowing to be considered a bottom end pipe.

Dont know what if any intake or internal mods you have but unless you have spent a ton of $$$ on internal engine mods that will enhance the torque and bottom end (this does change things some) you will want to check out all the disc type silencers (using the stock header, it just works better for bottom end on mostly stock engines) because they will allow you to dial in the amount of flow in the exhause which will help you to increase the bottom end grunt or lose some in favor of a top end hit etc.

And just for an extra bit of info many of the "builder" pipes are from a design that originally used a disc set up and they just replace the discs with a turn down that increases the total flow, and that is great for mid to top, but not bottom end especially on a mostly stock engine.

Hope that helps.
 

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440ex4me said:
Seems like your going to have to look around for more info cause all the pipes listed so far are way too free flowing to be considered a bottom end pipe.
Do your homework, the head pipe plays more into you power curve then your silencer. That's why in this case I didn't recomend changing it.
 

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Do your homework, the head pipe plays more into you power curve then your silencer. That's why in this case I didn't recomend changing it.
Dont worry I have done my homework and tested them too, and with the stock internals you just dont need to throw your money away especially if your looking for more or less of a loss of bottom end torque.

So I guess we agree on the head pipe issue, even if I was a little confusing in the earlier post. When I said "pipe" I was refering to silencer or one time the whole system.

For anyone not completely getting the idea lets try and make it simple, if the engine is not creating enough exhaust gases to need the extra flow what good is it being able to out flow the engine. IF you dont trust me on this you can call just about every engine builder in the country and ask them their thoughts on a internally stock 400ex being set up for torque and using an aftermarket header. I bet even a few that sell full systems will tell you its money better spent on other mods.

Now not to make things more confusing but if you were to bore it out, add a hi comp piston (and set it up right too) change the cam, get it ported etc it would add a lot of potential to the engine and also enable it to flow more (try and think of an engine as a air pump, and the fuel is only used to allow it to suk in more air etc) and this would make better use of a better flowing exhaust (all rpms ranges) and the added comp would help on any loss of bottom end.

There are a few members on here with some large bore thumper EX engines that were set up for torque, and though the engine could could handle a serious free flowing head pipe and silecer not all of them have changed the head pipe since it does help keep more of the bottom end grunt.

I dont remember which builder it was (may TC?) that used to recomend keeping the stk header on his big bore engines but I know its TC that uses a silencer with the stocker for his pipe, and it seems to work very well even on the larger displacment engines.

Also I can tell you from trying different things on mine that running a straight thru silencer (eg. lrd sparks etc) will change the power curve a whole lot from what you would get from a disc set up with only 10 or so discs. There is a deff loss of bottom and also a gain on the top, and you will be able to feel it no problem.

I hope I didnt come off as a know it all or something cause thats not the intent, but I just try to offer solid info for others and dont like seeing so many other riders get caught up in the hype and throw away money they could have used on something else (how about some shocks :))
 

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nice explination 440ex4me. :tup: :nod:
but ya left out 3 very critical words that would have pretty much summes up the question about torque and the stock header....
Exhaust Gas Velocity
 

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LRD i got it on mine and i love it its ur best pipe out there id go out and get it if i were u.......................
-case
 

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what about the bills pipe and the e-series pipes, are those good for the ex's?
 

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NitrousGuy said:
nice explination 440ex4me. :tup: :nod:
but ya left out 3 very critical words that would have pretty much summes up the question about torque and the stock header....
Exhaust Gas Velocity
Nitrous good point, but I wasnt sure if I was being followed with what was originally noted and therefore deff didnt want to get into anything beyond flow.

If we all care to spend the time in learning all about this stuff that would be great, but for the most part the majority of people seem to only want to hear what brand pipe etc and are not actually all that concerned about the how or why aspect of things.

I dont know maybe I am messed up cause I have questioned just about everything that was used or recomended etc, and have had some very interesting discussions with some of the better builders and parts mfgs in the industry to learn what I felt I needed to in order to be able to better pick my mods and set up the quad etc. Ever get a chance to have an indepth talk with someone who had been doing internal mods on this type of engine for years about the relationship of intake and exhaust volume v/s velocity etc? I have to admit much of this does roll over from auto engines but with the smaller cc's a lot of things were much more critical than I would have believed.

Point is that unless were willing to put in the time to learn and picking people brains (and the right people too) and getting "real" info on the why part of modding our engines we are only following some sort of trend or hype from the parts mfgs and I dont think thats the right way to do it.

So if there are enough of us that are interested in getting into the more detailed part of all this I am all for it, and as much as I would be happy to share any knowledge I have gained I would really be interested in learning from those who have more experience or knowledge.
 

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440ex4me said:
NitrousGuy said:
nice explination 440ex4me. :tup: :nod:
but ya left out 3 very critical words that would have pretty much summes up the question about torque and the stock header....
Exhaust Gas Velocity
Nitrous good point, but I wasnt sure if I was being followed with what was originally noted and therefore deff didnt want to get into anything beyond flow.

If we all care to spend the time in learning all about this stuff that would be great, but for the most part the majority of people seem to only want to hear what brand pipe etc and are not actually all that concerned about the how or why aspect of things.

I dont know maybe I am messed up cause I have questioned just about everything that was used or recomended etc, and have had some very interesting discussions with some of the better builders and parts mfgs in the industry to learn what I felt I needed to in order to be able to better pick my mods and set up the quad etc. Ever get a chance to have an indepth talk with someone who had been doing internal mods on this type of engine for years about the relationship of intake and exhaust volume v/s velocity etc? I have to admit much of this does roll over from auto engines but with the smaller cc's a lot of things were much more critical than I would have believed.

Point is that unless were willing to put in the time to learn and picking people brains (and the right people too) and getting "real" info on the why part of modding our engines we are only following some sort of trend or hype from the parts mfgs and I dont think thats the right way to do it.

So if there are enough of us that are interested in getting into the more detailed part of all this I am all for it, and as much as I would be happy to share any knowledge I have gained I would really be interested in learning from those who have more experience or knowledge.
pure poetry :tup:

i say fawk em if they dont want a technical answer. because ( as everyone who has ever pm'd me on here about a question can voutch) i very rarley give a short answer.
if they dont want to hear the theroy of WHY i think "part a" is the way to go, than dont ask me the question to begin with.
an opinion without an explination is not an opinion. its just a guess.

personally i think, as im sure you do as well, that there is not ENOUGH
in-depth technical discussion.

now, on that note, on with the tech discussion.......

the reason the stock header on a stock engine will yield the best torque curve is because of the exhaust gas velocity.
a larger aftermarket header will slow down the exhaust gas flow on a stock engine due to the larger volume on the header.
slower exhaust gas velocity hurts intake as well as exhaust scavenging, especially on a lower duration camshaft like the stock cam.

while the larger volume aftermarket header will help torque up in the curve, it will hurt it down low, where it counts, especially on a stock engine. the reason it will help up top is because of, once again, exhaust gas velocity. the velocity will be great enough to assist in intake and exhaust scavenging, but my that time your almost " off the cam".

once ya add a cam and a HC piston, the the stock header becomes more of a restruction. exhaust gas velocity will only travel so fast, then backpressure really starts to play into the equasion.
the larger header will allow the exhaust velocity to hit that sweet spot, where its not corking the system, yet is not too free flowing to drop the velocity and make poop for torque.

and also, header diameter and length plays a HUGE part in sonic tuning.
 

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NitrousGuy said:
440ex4me said:
NitrousGuy said:
nice explination 440ex4me. :tup: :nod:
but ya left out 3 very critical words that would have pretty much summes up the question about torque and the stock header....
Exhaust Gas Velocity
Nitrous good point, but I wasnt sure if I was being followed with what was originally noted and therefore deff didnt want to get into anything beyond flow.

If we all care to spend the time in learning all about this stuff that would be great, but for the most part the majority of people seem to only want to hear what brand pipe etc and are not actually all that concerned about the how or why aspect of things.

I dont know maybe I am messed up cause I have questioned just about everything that was used or recomended etc, and have had some very interesting discussions with some of the better builders and parts mfgs in the industry to learn what I felt I needed to in order to be able to better pick my mods and set up the quad etc. Ever get a chance to have an indepth talk with someone who had been doing internal mods on this type of engine for years about the relationship of intake and exhaust volume v/s velocity etc? I have to admit much of this does roll over from auto engines but with the smaller cc's a lot of things were much more critical than I would have believed.

Point is that unless were willing to put in the time to learn and picking people brains (and the right people too) and getting "real" info on the why part of modding our engines we are only following some sort of trend or hype from the parts mfgs and I dont think thats the right way to do it.

So if there are enough of us that are interested in getting into the more detailed part of all this I am all for it, and as much as I would be happy to share any knowledge I have gained I would really be interested in learning from those who have more experience or knowledge.
pure poetry :tup:

i say fawk em if they dont want a technical answer. because ( as everyone who has ever pm'd me on here about a question can voutch) i very rarley give a short answer.
if they dont want to hear the theroy of WHY i think "part a" is the way to go, than dont ask me the question to begin with.
an opinion without an explination is not an opinion. its just a guess.

personally i think, as im sure you do as well, that there is not ENOUGH
in-depth technical discussion.

now, on that note, on with the tech discussion.......

the reason the stock header on a stock engine will yield the best torque curve is because of the exhaust gas velocity.
a larger aftermarket header will slow down the exhaust gas flow on a stock engine due to the larger volume on the header.
slower exhaust gas velocity hurts intake as well as exhaust scavenging, especially on a lower duration camshaft like the stock cam.

while the larger volume aftermarket header will help torque up in the curve, it will hurt it down low, where it counts, especially on a stock engine. the reason it will help up top is because of, once again, exhaust gas velocity. the velocity will be great enough to assist in intake and exhaust scavenging, but my that time your almost " off the cam".

once ya add a cam and a HC piston, the the stock header becomes more of a restruction. exhaust gas velocity will only travel so fast, then backpressure really starts to play into the equasion.
the larger header will allow the exhaust velocity to hit that sweet spot, where its not corking the system, yet is not too free flowing to drop the velocity and make poop for torque.

and also, header diameter and length plays a HUGE part in sonic tuning.
:tup: :tup: :)

Now were getting someware.

I know not everyone agrees with the stock header on built up engines (see how different the TC set up is compared to the sparks etc) and I do know its all about how the added velocity helps this engine v/s increasing flow and how thats also an advantage, but without access to the proper equipment and only going on "seat of the pants dyno" etc its really tough for the average rider/mechanic to dial the ratio of the two in properly.

Personally I am planning on trying to get some real info from my own set up on this by messing with both porting and different headers but am not sure when time will allow it. Until then all I am sure of is that with the right amount of all of the above and a stock header it does make a good amount of torque, and the difference of the larger header on this one will soon be known.

Lets keep it going and hope to see some input or questions from other members.
 

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i agree about the butt dyno. its about as unrealiable as a virgin on prom night. without hard data, all were goin is really guessing.

your porting/dyno experiament is gonna take alot of time and resourses, but you really should post your findings, and give us as much data as you can, like cam profile, CORRECTED HP and TQ ( dont even get me started on that topic :lol: )

and your right on the money. its all about the best compromise.
there is no such thing as the perfect one-size-fits-all engine package.

cylinder head porting is a really tricky subject. simply because 10 different head machinests/engine builders will each have 10 different porting techniques and theroies, and they will be very close in power.
be it rasing the port floor, blending the bowls, using epoxy to re-shape the ports, as well as the runner/port volume. not to mention choosing a cam with LCA's ( lobe seperation angles), duration and lift to fully exploit the headwork.

cylinder head theroy fasinates me, simply because there is not one way set in stone to achieve your goals.

so when ya start the experiment, please keep me in the loop. because im very anxious about your findings.
 

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Agreed on all.

Only issue I have is that of getting access to something beyond the "butt dyno" (have to love that one lol) and the only local guy I know wont allow anyone around during the runs, and that kills the idea of using him.

I am looking into some exhaust flow equipment (hope it works out cause its a sweet deal) but even with that its only a small part of the puzzle.

I would seriously love to have access to a dyno local or better yet find one cheap enough to just buy the damn thing cause that would allow to be much better able to get real info on all possible changes etc, but unless something unexpected happens the most I am expecting is some sort of flow bench, AF meter, and a trip to someones dyno.

Thats just not cutting it for testing small adjustments like port size or shape, different carbs, headers and the like, but maybe the best avail.

And if you think all this is a pain try and talk with some of those "professional porters" and gain any real info. I bet you will want to bang your head on the wall in no time :D but if we keep after it there is actually some who are willing to share, and if not everything (dont even expect it) at least a little bit here and there that if your good it can be pieced together to at least give us a half decent shot at getting it right, and like you say right isnt allways the same thing anyhow.
 
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