Pipe Shootouts

I just got the latest issue of Dirt Rider with the YZF pipe shootout and I was amazed at how much their results differed from the Dirt Bike shootout. The most glaring example of the disparity between the two is SuperTrapp. If I remember correctly, this pipe was totally panned by Dirt Bike. It sucked everywhere on their dyno tests and their tester didn't like it. But in Dirt Rider it made the highest peak HP numbers out of all the pipes!

In contrast the Yosh pipe garnered raves by Dirt Bike and did great on their dyno test but had some of the worst dyno numbers in the Dirt Rider test (but their testers did like it). I think Dirt Rider used the dyno at RPM and I think Dirt Bike used White Brothers? (Sorry, but I am only going from memory, I was going to dig through my stack and find the Dirt Bike issue to compare directly but didn't have time).

In summary the Dirt Bike test winners seemed to be Yosh/DSP (Yosh makes the DSP), & GYT-R w/ PC T4 a runner up. In Dirt Rider the winners seemed to be White Bro.s (by far the best dyno numbers for all combo.s) and SuperTrapp. Both tests did note, however, that it was very tough to improve upon the stock header/silencer.

I can see how diff. riders on diff. tracks give widely disparate opinions and understand how diff. dynos can give diff. readings but there were a few examples that were diametrically opposed (esp. Yosh and SuperTrapp). I also realize that dyno results are not the panacea for comparing pipes. A dyno run is conducted at WOT right? I don't know about you studs but I don't spend a lot of time with it completely wicked. But what gives? Was SuperTrapp tested in DB a diff. model? How could two separate dyno tests be that different?

All these damn pipes are expensive, I bought the PC T4 ($450) in part because I needed the S/A for racing but Dirt Rider's test made me wish I hadn't. I bought the PC after reading the Dirt Bike test, but the Dirt Rider test makes me wish I bought a WB Pro-Meg/E-Series.

What other pipes have you guys ridden 426s with and what are your opinions? I do like my PC pipe, midrange feels both smoother and stronger, which is very similar to what their 2-stroke pipes do.

I'll compare both tests side by side and check back on Mon., but I wanted to see if you guys had any comments/opinions/insight.

Another thing that was a surprise is the stock pipe was quieter than the aftermarket pipes by a good margin.

In addition, I was surprised to see that the stock pipe held it's own and in many cases was better then some aftermarket pipes. Given that I'm an intermediate rider, the report has dampened my spirits to spend $300-400 for an aftermarket pipe. I don't think a few tenths of HP gain will make a difference to me. I'll save my money to repair the things that I break. That I'm advance at!

Tazeman

Tazeman,

I would imagine that aftermarket exhausts for race bikes like the YZ often sacrifice overall dyno numbers for better rideability. I know that the Pro Circuit pipe for my KX500 felt like it stole some top end for the benefit of a smoother but stronger midrange. I know, that is a different animal but the effect of the PC on my 426 was very similar.

As far as I know, and like I said in my post, a dyno run is conducted at WOT. I would imagine that an engine runs at different levels of efficiency for all other partial throttle openings. Point is that a dyno and your riding the track/course do not even remotely represent the same operating conditions.

Another point is that I'll bet systems for most race bikes are designed around getting the best dyno numbers, which engineers can measure, and not on making the bike faster while being ridden.

Despite what Dirt Rider dyno test said about my pipe costing HP, to me it still feels more responsive, and faster, but I don't go around the course at WOT...

Having said that I'm not sure if the difference my PC T4 made was worth $450 to me. In fact I'm pretty sure it wasnt (maybe $350?). And it is noticeably louder (if you can believe that) to boot.

Oh well.

Too bad I didn't know about the other, cheaper, spark arrestor options out there.

Not to hog this forum but, like one of the tests pointed out (don't recall which), the first pipe WB made for the YZ was good on the dyno because they focused on getting more overall power, but even their tester (Dubach?) didn't like it.

BTW Tazeman, are you advanced at breaking things or at fixing them? Or are you good at both like me?

[This message has been edited by Hick (edited 07-14-2000).]

Unfortunately, breaking them.

[This message has been edited by Tazeman (edited 07-14-2000).]

Did Dirt Bike do another shootout? The last one I remember was a while back, and was done with a 400, so it should be different. If Yamaha sold a system with a higher headpipe with a guard and a spark arrestor, I'd get rid of my Big Gun to buy it.

Lets not get to upset with the reports from the different mag. articalls. Try to keep in mind that every business is motivated by the folding green. He who pays the most green gets the best review. You need to look no further that the cigarette industry.

Originally posted by derwud:

Did Dirt Bike do another shootout? The last one I remember was a while back, and was done with a 400, so it should be different. If Yamaha sold a system with a higher headpipe with a guard and a spark arrestor, I'd get rid of my Big Gun to buy it.

Yes, last issue of Dirt Bike has 11 pipe shootout for 426 (Supertrapp, GYT-R, Yosh, DCM, DSP, FMF, White Bro.s (3), Pro Circuit, Big Gun).

GYT-R is a Yamaha product (Genuine Yamaha Technology-Racing) and has high, tight header but no heat shield.

If you like your Big Gun then don't read the Dirt Bike test. They preferred DSP, Yosh, GYT-R, PC and WB (in that order).

BTW, to correct first post in this thread, Dirt Bike used K&N Dyno and not WB.

And, yes, Supertrapp tested in both Dirt Rider and Dirt Bike was same model. On K&N dyno it lost power everywhere, on RPM dyno it made more than stock in many places, especially up top, and made most power of ALL pipes.

K&N rated stock peak HP at like 50, RPM was about 46.5 or 46.9 I think.

[This message has been edited by Hick (edited 07-17-2000).]

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