A dropping idle can also be caused by just cooling down the engine which is atomaticly done at idle when getting the right/rich mixture. The cilinder sceezes again giving the piston more friction and so slowing it down.
Depending on the status of the P/S set the effect can be more or less noticeable.

relationship between throttle and fuel consumption
 

question for you guys...

is the fuel being consumed at any given moment proportional to the amount that the throttle is being pulled?

so is there a decent amount of difference in fuel consumption at 1/2 throttle vs full throttle?

Proportionally speaking it depends alot on the carburetor and the needle taper being used.

just to make sure i'm understanding correctly...

i think you are saying that there is a relationship between the amount of throttle pull and consumption but the relationship varies depending on the carburetor?

Hi.

On my plane engines the throttle opening vs rpm is not linear:

Half open throttle = approx. 8500 RPM
Fully open throttle = approx. 12400 RPM

It is not the same type of carburators, but the function is the same.

It makes good sense, that you can drive a car as fast with a modest throttle finger instead of idle/fully open throttle. My guess is that the perhaps last 3000 RPM is the RPM range that really needs A LOT of fuel to achieve.

Cheers

EDIT: I could make some tests next year and calculate the RPM's with 1/4, 1/2, 3/4 and 1/1 open throttle. Could be alot of fun :)

I see rod replacement in your future ;-) LOL

... with the car driving on the track god damn it! :D

Easy now , don't get too excited :deathstar:D

I think this is enough .....
I do agree with you. Those are the most effective way

thanks
 

hey im new to nitro i just want to say thanks to all the experienced race and tech guys that take the time to post this sort of info its great it may be common knowledge for most but this article probably just saved me 300$ on a motor replacement once again thanks

Its all about sharing the info to help a fellow racer out

I'm glad you found the article useful

Happy motorin',
Monty

I have a HYPER MACH 28 it wont break lean till the motor temps get to 260 and screams went you lean it out by one hour. Thats from on top of the glow plug. There is steady thick smoke trail the hole time. bottom is perfect. The bearing are very smooth. Any advise would be helpfull.

Thanks bigmack

what kinda temp probe?

you might be sticking the probe wau too deep or the probe is way off.

tune by sound , the engine will let you know if its too lean by bogging on the low speed or the high speed ;)

One temp probe is a fluke other is extech. both are with in a few deq. of each other. The bottom end still has a little bog to it . I like for it to bog a little ,that way i burn the tire off on corners. It sound way too rich , when it sounds great the temps are over 300. Thanks for your info.

Bigmack

NOVAROSSI ENGINE TUNING
hsn is the control valve, set the control valve to limit high rpm's first when final race tuning . after doing so go to the lsn and lean until the engine keeps a consistent idle but does not ting when idling or starve for fuel as a quick throttling is applied , that is caused from lack of fuel on lsn . lower the idle until it is as low as you can get it and it will maintain a good safe idle during on track deceleration and on the bench for at the least 20 sec.
after you do the low end you will usually have to richen the hsn about 1-2 hours

there will be a few things that will need to be tweaked slightly but that will get you in the ball park .

OTHER ENGINES TUNE DIFFERENTLY !!!!

from page 1 ;)

the needles do effect one another yes , you need to find the proper balance between hsn and lsn , once this is done that balance doesnt change much .