[DeeBee]

I have a ported jug tuned to about 8500-9000rpm , its is starting on .030" over bore, Mikuni VM32, 3/8 Reed spacer, stock cage dual stage reeds, 20cc Hemi head, S-band at ~40%, 3 deg. .80mm, Currently on Toomey B1 pipe, w/ freshly packed DG Type II silencer.

At this point the Toomey has around 8 inches 2" X 3/16" of fiberglass heat wrap across the middle of the belly, which has done surprisingly well at Widening the band a little, when you first get on it from a stop or after a slowdown, power is down low for a few seconds of Wot until the extra insulation causes heat to build in the pipe and its effective rpm to rise. Pretty neat you can feel the difference between a long period off the throttle and just dropping a couple gears for a curve. Ride easy and it stays cooler, ride hard and temp goes up this effect is quite exaggerated by just a little heat wrap ,possibly because the Toomey is Fairly thin.

It has been a neat experiment and timing adjustments can make quite a difference in the effect, but in the long run a pipe designed with a particular rpm in mind should come quite a bit closer to being ideal, although the extra heat due to making more power does bring the rpm range up somewhat versus a stock motor.

Maybe a better question is the best way to determine a good estimate for exhaust temp range, to better calculate tuned rpm of a given pipe?
Of course would also need cone characteristics, that support the type of powerband I am looking for which the Toomey does, I just am not sure how it will match the new porting. But that is a whole different can of worms.

 

[DeeBee]

As usual when there isn't a readily available answer, I ask, and continue to search and research. I also report my findings and thoughts for others with similar questions .

I wrote several companies inquiring, about the Tuned Length, suggested rpm range, if it was suitable for a mildly modified motor, power characteristics such as smooth or abrupt hit, wide and flat or tight and sharp peak, drop off rate(sharp or lots of over rev)

So far I have got zero responses, not even a response such as we feel XXX pipe in our line up would best suit your engine.
A lot of the information is general and subjective yet no one even replied with something as vague as
Wide power band, or suitable for turned motors.
I even went as far to include exhaust duration, peak HP rpm, and expected BMEP of my motor, I would have thought that someone with anything close or that just wanted to sell a pipe would have replied with XXX is just what you need.

I guess they hope you will buy one of each and test them all, lol
Anyhow ,rant off,

It seems like just about any of the right bends could be a good match, as most are designed for higher rpm and many for modified motors.
Some of the Higher rpm MX style pipes, Including Pro-Circuit, Toomey B1, FMF SST, etc may also fit the bill, but with the Blaster being air cooled, depending on a pipe designed for Stock flow and thermal load, it might be safer to at least go with a pipe designated for mildly modified motors.

Another thing to consider is with stock stroke anything over 10,700 rpm is asking for trouble, and the 1mm thick rings included with many Blaster pistons including Wiseco Pro-Lite series can flutter and collapse at or above 10,000rpm.
So unlike with a stockish motor where plenty of over-rev is desirable, a motor that is already tuned to make power at a higher rpm, 1500-2000 higher in my case , would be better off with a little extra power at or below peak rpm, as opposed to being able to rev the motor past a safe rpm.

Anyhow I am certainly no expert, if anyone has and corrections , info to add or just a different opinion please speak up.

Althought I didn't find any useful information on mainstream pipes, I did find 3 pipe schematics for the 200cc blaster at various levels of tune, created with a professional grade simulator. This info could be invaluable, if you were to make or have your own pipe made, or even as a baseline to compare other pipes to (if you can get the measurements).
This combined with readily available knowledge of what each part of a pipe does and how various angles and diameters affect the Tune would be enough for the aspiring tuner to make an informed decision, particularly if he were to build one of the
Pipes shown in the link.



http://www.blasterforum.com/threads/pipe-design.41094/

DeeBee

 

[John Tice]

Arlan Lehman is your man Phone number (503) 522-2465 LED Performance

John Tice
503-593-2908 Alternate 541-508-3944
www.smallenginemachineworks.com & www.nwsleeve.com
Turning Custom Cylinder Sleeves Since 1971

 

[DeeBee]

Thank you John , when money allows I plan to have a new head cut , and pipe built.
I checked out the LED performance website and I must say Arlen makes some beautiful pipes and intakes, I got a feeling they perform as good as they look.


Right now I got a jug wih a hot trail port, or mild mx port and a Hemi head , I expect about 150 psi with current porting and .030-.035" squish height. But it is sitting on the back burner for want of a .030" over forged piece, realistically it will be early spring before it's running, maybe mid summer or fall before I am able to push squish ban d width and chamber size down, as well as decide on pipe characteristics. I gotta be careful with the power I am trying to make with stock castings, as you know heatsoak can quickly kill alot of power and or the piston especially on an aircooled motor.

 

[DeeBee]

After placing several emails to a few different places, I got an email back from Rich Daly of Dynoport who was able to get a semi custom pipe out to me in a couple weeks time.
So far fit and finish (Raw pipe w/ Aluminum silencer) is nice, and leak free. Various parts of the pipe are from stampings such as the main chamber , where others are built to fit I haven't run it yet, other than a test fire as my plastics are off including, factory airbox.