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20% Nitro or 30% nitro,?

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CorradoPsi already hit on this, and I totally agree w/ him. You should check out the Trinity Monster Horsepower 30%. Plus, it has 12% oil. So that is enough to prevent the extra wear on the engine. I just switched to that at the end of last summer and have decided that's all I'm going to run w/ in all my mills. You get the benefits of 30% and still have the lube factor for protection.

When I compare it to the O'Donnell 20% I used to run, I realize that I would push the engine and lean her to the edge in order to get the power I wanted. Now I can run richer (and w/ cooler temps) and still achieve the same power level as I did w/ the O'Donnell.
 
What you said about it being too lean on top and too rich on bottom makes a lot of sense. The other day it was soaking the table w/ excess oil while idling, but ran hot ,275 after a few laps. I will be making your recommended adjustments.
Thanks
 
Some motors come shimmed for 20% (WS7II for example) and some come shimmed for 30% (Nova P5 for example). Can you run 30% in a WS7II? Sure just add the proper shim. Can you run 20% on a P5? Yeah, and it'd run fine. If you're really anal about performance, you can substitute a thicker shim for a thinner one (have no clue on the details).

Most people say 20% runs hotter than 30%. I haven't seen it first hand, but I don't dobt it.

Also, don't go down lower in nitro %. If you run 20% and then switch to 30% and then back to 20%, dont' be surprised if you have less performance at 20% than you did previously. Once you go up, you can't go down.
 
I've talked with several racers who "seem"pretty knowledgeable, they've all basially said that you can switch from 20 up to 30% and then back down again without any problems other than having to completely re-tune. So who's correct?
 
If you look at the logic... The 20% burns hotter, making the engine expand more... then you switch to 30% which burns cooler, makes the engine expand less... wearing down the piston just ever so slightly. Then you switch back to 20% and it heats up more... There is now more of a gap between the piston and the sleeve, making less power.
 
.21Rc10GT said:
If you look at the logic... The 20% burns hotter, making the engine expand more... then you switch to 30% which burns cooler, makes the engine expand less... wearing down the piston just ever so slightly. Then you switch back to 20% and it heats up more... There is now more of a gap between the piston and the sleeve, making less power.
Click to expand...


whoa there buddy, how in the world did you come up with that. when the engine is tuned properly with either fuel, it will run roughly the same temperture. maybe 10* difference under identical atmospheric conditions. you can safely switch back and forth as much as you like, but you MUST retune every time. the point that BigFreak, was making, is that once you experience the power of 30%, you wont want to go back to 20%. if you do go back, you will have a tendency to try and make the same power with the 20% and thus burn up your engine in the process.
 
yes, now that i read what i wrote, i find i am wrong. I was just trying to say something that sounded like it had thought put into it.... :hammer:
 
its all good. I'm just trying to keep the facts straight for the inexperienced guys ;-)
 
(With an Elvis like tone), Ah,thank you very much ah! Corradopsi, that makes a lot of sence. I knew there had to be a better explanation.
 

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