My butt dyno...

[ataDude]

... and a few head-to-head runs against a "benchmark" DL1000 yesterday, tells me that the Spyder likes back pressure.

As you probably saw in the other "Now mine..." thread, I installed a Yamaha Warrior exhaust Thursday... and got to really run it on Saturday. It is actually quieter than the stock muffler which leads me to believe that it produces more back pressure... it's certainly not a straight like the Micron or others.

It seems that the Spyder was performing better... not markedly... probably in the few tenths per 1/4 mile... but better.

From a cooling system perspective, there was no change... from three to five bars... depending on conditions.

As they say, "You drive torque, you brag about horsepower".

Any comments on the back pressure thingy?

The 155mm howizer:
http://www.st-owners.com/forums/picture.php?albumid=28&pictureid=3503

[NancysToy]

Sounds feasible. Lots of engines like some back pressure, or are at least tuned for it. Since even the BRP techs can't get into the ECU to change the fuel mapping and timing, there are going to be limitations with anything that breathes different from the standard exhaust, and perhaps the Hindle, which BRP has designed for and tested. Sounds like you have confirmed it.
-Scotty

[Lamonster]

Well I don't think so but hey it's your butt dyno and I'm not touching that one. :D

[DragonSpyder]

My guess is the free flowing exhaust wins in the 1/4 mile assuming the fuel mixture is correct for that pipe. The exhaust with more backpressure would probably win in 300'. That is my experience from drag racing ATV's. We had MX/low-end pipes and drag/free flowing pipes. The drag pipes would always pull up top but the low-end pipes pull much harder out of the hole. That would explain your butt dyno!

[NancysToy]

Wonder if I can get plans in Popular Mechanics to build one of them butt dynos? LOL
-Scotty

[retread]

You can't build 'em, Scotty, you have to grow 'em.:yes::joke::yes:

[ataDude]

Well I don't think so but hey it's your butt dyno and I'm not touching that one. :D

I'm glad you're in TN..... :joke: :D

.

[ataDude]

Wonder if I can get plans in Popular Mechanics to build one of them butt dynos? LOL
-Scotty

I'll be glad to send you the plans for $50. PayPal me the money, PM your address, and I'll ship 'em to you. :yes:

.

[ataDude]

My guess is the free flowing exhaust wins in the 1/4 mile assuming the fuel mixture is correct for that pipe. The exhaust with more backpressure would probably win in 300'. That is my experience from drag racing ATV's. We had MX/low-end pipes and drag/free flowing pipes. The drag pipes would always pull up top but the low-end pipes pull much harder out of the hole. That would explain your butt dyno!

You and HDX are certainly right about more back pressure = more torque, generally on the low end. Normally, I can tell the difference at the low end but see a sacrifice at the high end.

But this seemed better all the way to red line and at speed (120 mph+). I was surprised and thus the post!

Thanks!

[rkteck]

[quote=ataDude;51339Any comments on the back pressure thingy?[/quote]

I just removed the baffle on my Yoshimura Exhaust and in the back of my mind was thinking the same thing. It felt a little less responsive. I just figured my brain was a little off due to the extra noise but after reading your post, it made me realize that the baffle was probably helping in the low end.
I will probably put it back since I prefer to be quicker off the start.

[Lamonster]

I just removed the baffle on my Yoshimura Exhaust and in the back of my mind was thinking the same thing. It felt a little less responsive. I just figured my brain was a little off due to the extra noise but after reading your post, it made me realize that the baffle was probably helping in the low end.
I will probably put it back since I prefer to be quicker off the start.


I'm running with the baffle in my Yoshi too and it runs great and the sound is perfect. :doorag:

[Latemarch]

I'm surprised that no one has mounted an accelerometer to their spyder.

[kiwi]

Seeing as a real dyno run with a spyder is out of the question has anybody tried either of these units?





http://www.gtechpro.com/index.html



http://www.zercustoms.com/news/iPhone-Dyno-Application.html

[ataDude]

Actually, Magic Man is working on a "dyno magic black box" which allows you do disable the VSS while you're on a dyno.

That should solve the problem. :D




Seeing as a real dyno run with a spyder is out of the question has anybody tried either of these units?





http://www.gtechpro.com/index.html



http://www.zercustoms.com/news/iPhone-Dyno-Application.html