Goaferboy

what % fuel should i run in my hyper 7?

Giles300-72

My Feedback: (2)

It really doesn't matter. You will get all diff kinds of answers. I found that O'donnel 20% gives me the best performance of anything I have ever used. And it is safe and easier on the engine than 30%. You really want tell much of a diff between 20 and 30.

Goaferboy

would 16% be ok?

Giles300-72

My Feedback: (2)

I don't see why it wouldn't. I am no expert on fuel but it shouldn't hurt. You will loose a little power but if you are only bashing then it should be fine.

JamesJenkins

yea 16% should be fine, thats what i use anyway and ive been fine....

Goaferboy

does different fuels have different effects on the temperature of the engine? iv hear the lower the % the higher the engine temps and the shorter the engine will last. this seems dodgy to me but i want to be sure.

SKYLINE350GT

Yes because the less nitro the fuel- the more you will lean it to make more power- thus it will run hotter. As for noticing a difference between 20% and 30% you will DEFINITELY see a HUGE difference between the two. I say atleast with 20% if not 30%- but if you want a happy medium get yourself some 25% fuel.

vti-chris

It doesn't matter what you use just stay between 20%-25% you should be fine,as for which brand,try what your LHS has and see which one works best for you.
That's what i did,and even though i found posts which said "stay away from Model Technics",i did at first,i tried 3 different fuels,but when i tried this one(Mod.Tec.),it was great for me and the conditions here at my country!

Foxy

Its been said before on this forum by Uberchav (an experienced hyper pilot), that the Hyper 8 port (if that's the engine you are using?), is shimmed for up to 25%, so I wouldn't recommend going to 30%, though I must say I do not know what the implications would be of doing so. Can anyone enlighten me regarding the purpose of shimming for different fuels?

vti-chris

Shimming the head lowers the compression=less prone for detonation

Higher nitro fuel=more power=burns faster with higher burning temps in the combustion chamber

With this the chamber gets really hot and the mixture can back-fire before the piston reaches TDC with the risk of broken piston or rod or both...(While the piston goes up it can fire up the mixture and push it down before going at TDC)

Shimming the head lowers the compression,which lowers the timing of "ignition" of the mixture thus preventing detonation.
The opposite works for lower % nitro,you need more compression to keep the right timing and burning characteristics of the fuel!

NOT IN DETAIL BUT IN GENERAL THIS IS THE WAY IT GOES!!CORRECT ME IF IM WRONG!!

Foxy

makes sense, but I would assume that shimming would increase the compression....maybe I'm wrong, I'm sure someone will tell us...

vti-chris

Adding shims=bigger combustion chamber=lower compression
Removing shims=smaller combustion chamber=higher compression

I'm SURE on this one!!

Foxy

OK mate....

Goaferboy

i think its a 4 port engine if that helps

casper7

Its not the buggy but the engine that counts, I run my sons Hyper 21 4 port on 25% no problems at all, I run my RB Ws72 on the same 25% big bang.

Both cars are Hyper 7's one sport the other is a PBS.

Mike

Da Smak

Adding shims=bigger combustion chamber=lower compression, Retarded timing.


Removing shims=smaller combustion chamber=higher compression, Advanced timing.


Both are bad with the wrong % fuel.