Engine bogging down at full throtle...

[jaymz383]

I just bought a maximum st pro and put a dynamite .12 spd engine in it. I just finished breaking it in and have it tuned to where the temp should be at according to the engine specs (put a drop of water on the head and it should dissapate in 3-5 seconds). When I go full throttle it goes strong for about 2-3 seconds and then it boggs way down or dies if i stay in the throttle to long. If I hold the throttle about half way open it will go pretty well and even shift into 2nd gear sometimes, but if I open it up even at speed it still boggs. I have no idea what is wrong b/c this is my first nitro car and really dont know much about them. Does anyone know how to fix this?
Thanks,
Jamie

 

[mcvickj]

It sounds like your HSN is too rich. Lean the needle about a 16th of a turn.

 

[Domination]

make sure the engine is good and warm but if after 1/2 tank to a tank and its still bogging then turn the HSN 1/16 of a turn like MCV said

 

[Krusty]

Jaymz,
What you describe is typicaly a "LEAN" condition. The engine is not getting enough fuel at full throttle. Richen the HSN by turning is counter-clockwise in one eight turn increments testing each adjustment with a high speed full-throttle run. You will discover the point where the engine will not "bog". Do not continue to lean out the motor. If you do, you may damage it.

 

[FlyinRazorback]

I agree with Krusty. Sounds to me like your HSN is lean.

 

[kyosho1]

Hi,

Sounds like its too lean to me too. I had that problem, and it was the nitro was way too low. Increase the nitro in your fuel to about 20%, open the needle valve about 1 turn. Then she'll perform on full throttle.

KYOSHO 1

 

[jaymz383]

Thanks everybody, I tried that today and it seems to work but it still looks like it could pull stronger. I am gonig to borrow a temp gun this week so I can get the temp right.
Thanks again,
Jamie

 

[mcvickj]

Ok. That is why I usually don't chime in on engine tuning because I have such a hard time my self. I would think that an engine bogging down would be to rich and if it cuts out before it gets to full RPMs it is too lean. :shrug: I'm glad that someone else was able to correct me and help you get it running better.

 

[olds97_lss]

If it gurgles at full throttle it's to rich. If it seems to lose it fullness of sound or go to a high pitch/tone at full throttle, your to lean. If when you let off of full throttle it sticks high for 3 seconds or longer, your lean on the high and probably the low.

If it gurgles on take off after 10 second idle, your low is a bit rich. If it idles erratic, but mostly high, your lean on maybe the high and low.

Of course, keep track of your temps. I didn't do the spit/water drop tests. I bought an ir gun. It seems that anything between 200 and 260 (depending on the engine) is good. Preferably stay closer to the 200 mark for longer engine life.

Just my .02

This has been my experience on all 4 engines I’ve ran. Dynamite mach 15, OS 15 cv rx (2), OS 21 rg.

If it's cool outside, richen it up on the high and a little on the low. It will overheat even though the ambient dropped. The cooler air is denser which allows more O2 to get into the chamber. You will need to compensate by running richer than normal. In extreme low temps, keep a close eye on it until you know it's staying around 200. The temps will run away on you pretty fast. By extreme, i mean 0-40 f. Anything above 40 and they seem a lot less touchy.

Sorry for the long post, but i thought i'd try to save a few people with the headaches I’ve run into.

 

[wdavidhicks]

I still keep this chart handy for the changing weather conditions.