Exhaust Myths vs Reality

[wizard]

..warbaby, this ws an excellent presentation, and also you keep track of the follow-ups questions an' all, thanks!


1) So, if I understand correctly ther is NO exhaust system that can give torque to the entire rpm range (mainly below hp peak) AND add a few ponies to the peak point..

2) Which is the full exhaust system that YOU would recommend for more torque and what are the mods on ecu and/or shafts that would be necessary? I am talking particular here, so if you don't want to "expose" your preferences to common view, I will understand..

3) Weight of the standard system IS an issue! (..along with the heavy wheels, but that's another issue altogether..). I am willing to go for a full exhaust 41 system just for the less weight benefits alone. The HMF's I particularly liked but they use two cans. Should I "trade" the extra weight of the HMF's for the lighter single-can system, and how can I preserve the TORQUE (this is what I 'm after, couldn't care less about more "peak" hp power, too dangerous here in Greece to ride on those rpm ranges.. (..oh, well, occasionally maybe.. )




Thanks for an informative review, and if your time permits some answers to the above questions..

[TorontoBusa]

Originally Posted by [b

Quote[/b] (atticdog @ July 13 2004,22:46)]TorontoBusa
is it a BDE gen3?
and how many miles on the pipe?
Mine got abit louder after some miles on it

Not sure if its a BDE gen3, I bought the bike with it on. It is the full tatanium one with the titanium can.

The bike has 14,000 KMS (8,000 ish miles on the bike)

Not sure when the pipe was put on

[WarBaby]

1) * So, if I understand correctly ther is NO exhaust system that can give torque to the entire rpm range (mainly below hp peak) AND add a few ponies to the peak point.[/quote]
Some aftermarket exhaust systems increase torque throughout the powerband and also increase peak power. Torque is the force that actually moves the bike and horsepower is a mathematical function of torque which represents the amount work done relative to time. Most header/collector systems offer power increases in multiple ways. Some of those ways have systemic effects on power. By "systemic", I mean those gains that are spread across the entire powerband, not just the low, mid, or high RPM ranges. For example, replacing a stock exhaust that has sharp tube bends with an aftermarket exhaust with much milder bends will typically yield gains across the entire powerband because the sharp bends are a systemic pumping loss affecting the whole powerband. When pumping losses are reduced thoughout the powerband, torque (and hence horsepower) increase throughout the powerband since torque and horsepower are inseperably related.

2) * Which is the full exhaust system that YOU would recommend for more torque and what are the mods on ecu and/or shafts that would be necessary? * I am talking particular here, so if you don't want to "expose" your preferences to common view, I will understand.[/quote]
I am biased in favor of BDE exhausts (not because I sell them--it's the other way around). I am thusly biased because my extensive, comparative research led me to BDE as a leading system based upon overall performance gains, construction, weight, appearance, and relative cost. That is why I sell them...exclusively. There are other good systems too (Yoshimura, Muzzy, Akrapovic, etc.) but I determined that BDE offered the most for the least investment. Each has its pros and cons. There are also some exhaust systems that are very marginal in terms of performance but some people choose them because of their sound or appearance. At the risk of offending someone, D&D comes to mind. There are "cosmetic" exhausts and there are performance exhausts. With performance exhausts, form usually follows function and loudness is not a measure of power.

Weight of the standard system IS an issue! *(..along with the heavy wheels, but that's another issue altogether..). * I am willing to go for a full exhaust 41 system just for the less weight benefits alone. * The HMF's I particularly liked but they use two cans. * *Should I "trade" the extra weight of the HMF's for the lighter single-can system, and how can I preserve the TORQUE (this is what I 'm after, couldn't care less about more "peak" hp power, too dangerous here in Greece to ride on those rpm ranges.. *(..oh, well, occasionally maybe.. )[/quote]
If maximum performance is your main criteria, skip the twin muffler systems and enjoy the benefits of a lighter 4-2-1 or 4-1 system.

The possible loss of low RPM torque with a maximum exhaust system is a complex and sticky issue. The answer is... it depends (on several things)! I'll try to get back to this issue soon when my head is clearer. I've been awake way too long.

Later.....

[Revlis]

[USN05LE]

Warbaby, absolutely incredible post and info, (once digested). Here is the question, if you don't mind another. I put Yoshi rs3 boltons on my busa. If I understand your info, I paid $550 for looks and a little better sound. I have been looking for a better 4-2 header, because I like the balanced look of 2 cans. Any recommendations. Thanks for your time and knowledge.

Peace
Don

[WarBaby]

Hmmm.. I haven't been getting topic notifications lately but I found this thread "pinned" so...

Warbaby, *absolutely incredible post and info, (once digested). *Here is the question, if you don't mind another. *I put Yoshi rs3 boltons on my busa. *If I understand your info, I paid $550 for looks and a little better sound. *I have been looking for a better 4-2 header, because I like the balanced look of 2 cans. *Any recommendations. *Thanks for your time and knowledge. Peace - Don[/quote]

Thank you.

I did not intend to leave the impression that, for instance, your Yosh bolt-on cans do not produce power gains. Bolt-on cans are fine if that's what one wants but they can't produce the kind of performance gains that well-designed, 4-2-1, 4-1, or 4-2 full systems do when properly mapped. I believe your Yosh cans are of "straight-through" design, unlike the factory cans with their circuitous exit path. That alone should decrease pumping losses and yield some power gains, even unmapped, I dare say.

I also like the balanced appearance of a 4-2 full exhaust system. My personal orientation is simply performance first (4-2-1) and I don't have experience with any 4-2 Busa header systems. A lot of guys rave about their HMF dual can exhausts and I see no reason why HMF (and others) wouldn't make excellent power (again, when properly mapped) as several dyno charts have revealed. Just keep in mind that there is a weight penalty with twin mufflers that must be factored into the performance equation. The single most restrictive aspect of the factory system is the "X" crossover tube which virtually any aftermarket manufacturer could/should easily improve upon.

Perhaps some of the "4 into 2" guys here can give you more specific data about their performance gains.

[Bulldog 333]

Thanks for all the detailed info..........AWESOME!!

It took me about an hour to sift through it all to get anywhere near the comprrhensive point. This is another reason why I've held off on too many mods too quickly, I wanted to lurk here and pick up tid bits as they were offered.

Thanks much for all your effort.

[paineless4u]

I think this is a good cut and paste Term paper. Great info, thanks a bunch

[henryace]

WB I thought it was a very informative post...

[WarBaby]

Thanks gents! *It took a loooong time (and a lot of $) to acquire the info posted above and it is shared freely with all interested forum members. I hope it helps the decision making process for exhaust system selection and/or mods, whatever your performance preferences and riding style might be.

[Glamisman]

I have read the post and it got me to remember comments made on another site. Short version goes like this ... when the exhaust leaves the tail pipe there is still a benefit to be gained from the velocity of the gases and that is only realized when the angle of the tail pipe does not point up at all. The post goes on to state that if the tail pipe points up, it breaks up the low pressure zone directly behind the bike/rider causing turbulance and thus more drag. Looking at various exhaust angles of pipes on the market, I am not sure if this is just an urban legend or ?? WarBaby, what do you think?

[WarBaby]

I have considered the question of exhaust outlet orientation (and its effects upon flow) in the past and came to the theoretical conclusion that relatively small exhaust tip angle variations (from a horizontal plane) would have a miniscule effect, if any, upon power production. However, I've never seen any proof either way.

[douglasjre]

Thank you.

Is part #5 the PAIR valve that people talk about disconnecting? Is this similar to the valve I see under sport bikes in the exh system? Is this item opening and closing to adjust the timing of wave antinode?

[WarBaby]

Is part #5 the PAIR valve that people talk about disconnecting?[/quote] #5 is the PAIR pump assembly. Most owners remove it when installing performance headers to save a little weight and to reduce exhaust backfiring during deceleration.

Is this similar to the valve I see under sport bikes in the exh system?[/quote] Probably not. I think what you are refering to is the flapper/butterfly-type valve used by some manufacturers to reduce the amount of raw, unburned fuel that escapes the combustion chamber at very low RPM.

Is this item opening and closing to adjust the timing of wave antinode?[/quote] No. See previous question/answer. The timing of an antinode constantly (and instantly) changes with RPM making a dynamic device almost impossible to design. I know of no sportbike manufacturers that use dynamic anti-reversion mechanisms. Anti-reversion designs are usually static devices such as exhaust port ledges or rings inside the headers tubes that are typically found on low(er) RPM engines...cars and Harleys.

[2 Buku]

So, I have an 02 Busa and My builder mostly does track build applications, However, He does a street project about once a year. Next week my bike goes in for the "build".The plan is bigger intake valves, a bid boar kit and up the compression a bit. Although I do not have the exact specs, and considering that I am not going to the track (Well maybe 1ce) What brand is the best exaust for me?? What are the top 3 systems? What combo of can and tubes is going to be streetable and have rude mid and killer top end performance?

Thanks

2 BUKU

[PaceMaster]

Great read--just an opinion--the flapper valve in the lower section of the header...Honda's 929, Yammer Fz1, my old 89 FZR600--exup valve..varies the amount of back pressure at low revs to high...more backpressure at low rev's increases torque...less BP at high rev's increases HP's. ..so a system without this is a compromise design...the serpentine [Brocks] etc. probably mimic's the before mentioned valve.....EXUP.
Anywho--My Muzzy Ti 4 into one and PCII--seems very awsome..no valve, no serpentine---just rev's so much more freely than the stock X--header. Stock free reving around 6K felt like kinda punishing in a way...70 in 3rd...or so.
With the Muzzy in can cruise at any RPM----6-7-8------K. Peak torque starts at 6k---to 8K.....I love it. 91 torque at 7K at 5000' altitude--dyno proven..WooHoo.

[PaceMaster]

Responding to 2 Buku----Carpenter Racing Engines..has a 6 axis CNC machine---will port a Busa Head to their latest and greatest results---imagine--Header,Power Commander,port job, one camshaft='s 207 at the rear wheel..WoW---Stock pistons and valves--to boot. $1,400 porting, cam not cheap either ....wish i had the dough. But Dayum..i now have 168+ RW at sea level already---I have thought and thought--seems a waste to tear down a good runn'in engine.
That has bolt on's............that rock..if i have problems later..rod bearing or whatever..i would consider internal mod's.



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[2 Buku]

I know in the old days, A guy could get a port job cams carbs and a pipe and add 33% or better to his machine. According to my builder (Zlock Racing) In many of today's bikes (Especially the Busa) Changing the cam shafts without new springs will break stock springs and the factory Suzuki springs perform well. Next Zlock professes that porting (And I have seen beautiful porting by him & yes he has a flow bench) in a busa is gererally not needed. I was shocked! I always made great gains in improved flow but again the Japaneses at Suzuki have done their homework and produced a superior product. I'm sure with a plan and a cnc machine it could be improved on but $$$ VS HP. Since the teardown is iminent and theat is a hassle I want to do it right and I have a budget of 5 grand for the top end (Including the exaust).

WADDYD THINK?

2 BUKU

[frisbee]

Dam'n , how many gigabites of info does your head hold ? So in your opinion whats the best exhast for the busa or does mods make the differance ?

[WarBaby]

Great read--just an opinion--the flapper valve in the lower section of the header...Honda's 929, Yammer Fz1, my old 89 FZR600--exup valve..varies the amount of back pressure at low revs to high...more backpressure at low rev's increases torque...less BP at high rev's increases HP's. ..so a system without this is a compromise design...the serpentine [Brocks] etc. probably mimic's the before mentioned valve.....EXUP.[/quote]

Yes! The "back pressure" provided by the EXUP and similar devices minimize the amount of unburned fuel that escapes the combustion chamber at low RPM... more fuel burned = more power, at any RPM. But, even when fully open, such devices also disturb the laminar flow of exhaust gases at high RPM thus impeding full, high RPM power potential to a small degree. Smooth tubular headers and collectors (aftermarket exhausts) don't suffer this compromise. It's all a matter of what kind of powerband a rider wants his engine to have. *