shoota0075

wanting to know what you experts think, i have been told that even though my tsunami calls for 20% fuel , that 30% won't hurt it and i will see a huge diffrence in speed/performance....is this true thanks

ehroof

30% wont hurt it, you will just have to richen the needles a little, you will see a performance difference, not a gigantic one, there can be more engine ware with the 30%

Redcat Nick

I don't go higher than 20% in my small block motors. I do know some people that do run 30% in there small block motors. Like Eddie said you will have to richen up your needles a bit. But the one thing to keep in mind is that your engine life will be shortened with the increase of nitro content. I personally think that 20% nitro is plenty for the small block motors.

Kemo

Bumping up in nitro will not shorten engine life when you shim correctly. Thats a big myth that people always will throw around. A engine shimmed incorrectly will cause detonation and/or pre-detonation. Radio control car action busted that myth again in one of this years issues. You are adding more of an oxidizer, with the slight sacrifice of methanol. You aren't losing any of the lifeblood (oil).

if you shim it correctly, and bump up to 30%, the difference in power is definitely noticeable. you are going to notice a "crisper" response.

shoota0075

thanks for the info, but can you define "shim"

rclynx

AKA head gasket...........................and I beg to differ about the engine life, I did read the artical and proof is in the pudding and part of the pudding is working on and being around combustion engines for over 45 years[&o]

Kemo

if you have it shimmed correctly and are using the right glow plug and tuning correctly, you won't notice a loss of engine life. Detonation is what is the cause of loss of engine life when changing nitro % and not shimming correctly.

gotmonkeys

Kemo, i have a qustion for you. I recently went to 30%. I noticed a nice gain in performance from the 20% and had to richen up a bit. There is just one problem that we have found, the plug dosnt last very long and gets all black after a few tanks. I have tried all different heat ranges and i get the same results with the plug. Now me and an associate of mine run 3 different types of the sh.28 motors. We run the stock sh.28 p3 that comes with the hurricane and the monsoon, we run the sh.28 pro p3 and the sh.28mxp6. All 3 motors have the same problem with the plugs running 30%. Do you think that this could be a shim problem. I am no expert with these motors but i know enough to be dangerous. What is your insight on this? What have i missed? Thanks for your input. On a different note, running the 20%, i ran the same plug for about 2 months and had no problems with plugs until the switch to 30%

Kemo

so what we have to get figured out here is what plug are you currently using?

If its an OS plug in an SH engine, I suggest you use something else like a mccoy Mc9. Perfect plug for those of us who run above 25% nitro.

This is from the SH engine manual:

◎Fuel：Use only fuel specifically blended for high performance engines. SH engines are capable of using fuels containing 5%-40% nitro methane. If Using fuel containing more than 25% nitro, you must insert an additional 0.1mm head shim between the cylinder liner and head insert to lower the compression ratio.

rclynx

If your plug is black its running to rich (period) has nothing to do with compression[&o]

Kemo

if it is still shimmed for 20% nitro and he's using 30%, he runs risks of detonation and ruining an engine.

getting that set correctly is first and foremost most important. No sense in tuning it when you have your engine shimmed incorrectly, nor should you run it. as far as tuning goes when shimmed correctly:

High speed: 3 turns from closed
Low Speed...

To reset the low speed needle valve back to the factory setting,
follow these simple steps:
[ul][*] Open the carburetor barrel completely.[*] While holding the barrel open with your finger, use a flat blade
screwdriver to turn the low speed needle valve clockwise until it stops.
From this point, turn the low speed needle valve counter-clockwise
3 full turns. This is the factory break-in setting.
[/ul]

gotmonkeys

Thanks for the help kemo, but i switched back to the 20% on two of the motors. I still have a gallon and a half of 30% percent so i will shimm the 3rd motor and go from there. Thanks again.

Kemo

not a prob!

razormy

Where does everyone get shims for these motors?

So, on the SH P3 running 30% O'Donnell fuel, is it recommended to add a 0.1mm shim?

thanks

Kemo

local hobbyshop should have shims for most engines out on the market today. Yes, a .1mm shim

ehroof

the shim for an hpi .15fe will work on the .18 vx