Nitro buggy racing question

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badboy
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Nitro buggy racing question

Post by badboy » Sat Jul 18, 2015 12:21 am

Last week my sons and I went racing. After the first qualifier the buggy stalled because we ran out of fuel. There were two minutes of warm up and then the race.

For the second qualifier we came in and topped off so we would t run out of fuel. At the end of the second qualifier I plugged the exhaust to turn off the engine and it wouldn't stop. I kept trying but eventually had to pinch the fuel line to stall the engine. It seemed like it was hot even though I try to run a little rich.  I have never seen a nitro engine do that. The rpms dropped down but kept running while trying to plug the exhaust. I wish I would have taken the temp but didn't think about it because of trying to get off the track.
My son was driving real hard and staying on the throttle I don't know if that would have anything to do with it. I don't think anything is wrong I am just curious to know what might cause this.
I was also somewhat puzzled at our run times of about seven minutes because I was expecting more. I know I can use a smaller Venturi, I think I have a 6.5 in right now.  I think our driving style may have been a little to aggressive.  Who knows we learn something every time out.
Almost forgot, they had a monster truck class. There were about five vehicles including our savage. There were two revos and two electric something's. Our savage was the only one that looked like a monster truck. You couldn't hear the other trucks because our ERCM side bleed was drowning them out. Anyways my son got to first in a hurry and was pulling away when about halfway through the race we stalled and it would t start again. To be honest I didn't expect to race the savage and didn't put much time into getting it ready.

It got real hot throughout the day, about 101. Maybe my tune got off I don't know. I normally tune the day before the race and then adjust on race so that I am close. I am just not used to tuning on a starter box and it's pretty hard to hear on race day. Hopefully we will get better
BADBOY- Savage X: Picco .28,

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MonoSavageX
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Post by MonoSavageX » Mon Jul 20, 2015 12:46 pm

That's awesome that the only MT savage there showed them who's beast lol I read that and was like *censored* YEA!!!! to bad it didn't finish. But now that you know it will be even more beastly next time around. 8O
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If your not supposed to break them, why do they make new parts?

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Post by Squid » Mon Jul 20, 2015 3:41 pm

For race day, don't tune only on the starter box. Getting the tune set on race day is tough. I personally try to get in as many practice laps as piratical/possible to tune. I'll drive and have my pit guy with temp gun and tuning screwdriver in the pits. Not being able to hear your engine will give you fits for quite a while. I basically take it out with the tune it had at the previous race day or from the last time I practiced. After a couple easy laps, I will start to run it hard paying attention to how quick it accelerates, the amount of smoke trail, bogginess off corners, watching for a lean surge coming off the straight, etc. There are too many things to list them all, you even have to pay attention to grip to know if the tires are spinning and causing a slow acceleration. A thick line on the rims with a sharpie helps to show if you are spinning.
I have hand signals for my pit guy, pat my head means HS needle, pat my chest LS needle. Then point at ground for leaner, up for richer. Unless I make some wild gesture signaling big change between the 2 he will adjust the proper needle an hour at a time.
If it takes off from a corner ok, and there is a little bit of blue coming out of the exhaust at the end of the straight I will take it in and have my pit guy temp it. Not tuning to the temp, but just making sure it isn't running too hot.
Sounds ridiculous, but if you can't tune by ear you gotta do it by sight and "feel".

As far as the warm up, every nitro race I have been to runs IFMAR qualifying, meaning you are running on your own clock, not necessarily against the others on the track. They will announce "30sc to start", "20 sec to start", etc.
That's when you come in and do a quick top off. After the clock goes live you are on your own 5 min clock, as long as you cross the bridge starting your clock before the 1st guy that did makes his first full lap. Sounds way more complicated than it is.

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Post by badboy » Mon Jul 20, 2015 7:23 pm

MonosavageX
You're right the mt was the highlight of the day. The other guys looked like they were afraid to scratch their bodies and my son was driving like he was trying to blow it up. Ironically he drives the savage better than the buggy. I guess it's because he has so much more time driving it. From now on I will have the savage more prepared when we go to a track.

Squid
You are absolutely right it is going to take time to be able to tune during race conditions. Our tune was great in the morning but as the air temperature rose we should have leaned the needles if I am thinking about that correctly.
The qualifier conditions were just as you described. I thought for sure we could go seven minutes but let's just say there is a big difference in fuel consumption when comparing driving in your driveway and race conditions. We ended up with a lean condition at the end of the qualifier. In the second qualifier we topped off at 45 seconds. I don't think the tune was to far off.
We had a lot of fun and get better each time but we need some more practice
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