blaster B pipe on a RNSJ?

[keefer]

I think that you should be able to run whatever gas you run at sealevel for equal compression measured on the gauge.
I.e., if you measure 180psi (35cc domes) at sealevel, and you measure 180psi in the mountains (33cc domes), you should be able to run the same fuel.
There is less air at the altitude, hence less compression for given dome size.
You're not changing the volumetric ratio of the fuel air mix....you're just decreasing the efficiency of the motor (hence power loss).

I'm probably wrong though.

I think you are right, from the way I understand it. Less air = less power

 

[keefer]

hey keefer, got any pics with that pipe? just wondering how much "convincing" is needed and if its worth the savings.the blaster pipe is a limited and up for auction.FFP has an "upgrade" kit for 250.is the stainless steel chamber alot heavier than a limited SJ pipe?

I don't have any pictures of it installed, but I will try and get some. Not sure of the weight difference either, but I am sure it is heavier. If you use the original brackets you have to cave it in pretty good to clear the tank. I had to flatten the side next to the hull just behind the coupler also. Be careful there as it is along the weld and cracks can develop. Easily fixed with a TIG and some stainless wire.

You should have no problems selling the B1 limited chamber. I seem to have read where some of the blaster guys prefer them. You might consider just buying the SJ chamber instead, alot easier on the install and fit.

 

[rkymtnrider]

after reading your first paragraph, i have already come to the conclusion of your 2nd par.i will just focus on finding a SJ chamber. limited or mod? with the above engine sinerio. also with the elevation factor.

THANKS FOR ALL THE INPUT EVERYONE!!

 

[rkymtnrider]

BTW, it does also have a solas prop, no clue on the pitch.

 

[Matt_E]

FWIW, to get my Blaster mod (that I used to run) to fit, I had to dent the chamber right where the headpipe connects.
I didn't dent it at the tank - there I used a heatgun to slightly reshape the tank instead. Worked great.

 

[RMBC Freeride]

I know that Gloryfreestyle and RMBC have talked about how crappy their boats run at their elevations in CO. I was thinking that before Neil built his lameys and strokers that he had to run small domes to get the compression up but still ran 93 octane. Even with that they talked about the boats still did not run nearly as well compared to lower elevations. I think the biggest concern would be having to run 110 octane if you ever dropped off the mountain.

I think that you should be able to run whatever gas you run at sealevel for equal compression measured on the gauge.
I.e., if you measure 180psi (35cc domes) at sealevel, and you measure 180psi in the mountains (33cc domes), you should be able to run the same fuel.
There is less air at the altitude, hence less compression for given dome size.
You're not changing the volumetric ratio of the fuel air mix....you're just decreasing the efficiency of the motor (hence power loss).

I'm probably wrong though.

I think you are right, from the way I understand it. Less air = less power

Yes, yes, and yes... Less air, less oxygen, less air density, less indicated compression. All adds up to LESS HORSEPOWER:banghead: .

Back when i could run pump gas, I would use (for example on a non-ported 701) 31cc domes here in CO for about 175psi. Of course I would have to switch to say... 35cc domes at or near sea-level to keep riunning pump gas there.