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trying to figure out my truck.

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bigboystoysguy

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hey guys,
this last saturday 30% nitro boy came by my work to drop off my bearings and since i havent posted pics yet hehadnt seen my truck. so i showed him and then we wieghed it compared to a stock t-maxx. check this out stock t-maxx - 9lb 4oz i think thats what it was, well my truck - 8lb10oz with sirio .18 ti skids dace predator chassis rpm all around and traxxas alubulk heads. this truck is super tough and at 10 oz lighter with a sirio and it was setup sportmaxx style with a two speed. in theory even at the altitude I'm at my truck should rip a new ass in any terrain I'm on.
well it doesn't my truck actualy kinda sucks. it was doin pretty good but it has just gone down from there. my buddy jon was there too(i know you remeber him 30% crazy a.d.d kid) and he pulled off his .21 filter and put it on my truck, well that actualy helped alot!! alot alot!! but even after the filter change 30% said it should still be performing better than that. so is there any check list i need to go over, like a performance check. is there any info you guys need to help me fdigure this out?? big boystoys thanx in advance!!

bbtg
 
What pipe are you using? The guy at the LHS is running the same engine with a Motor Savers filter and the Sirio Big Bore pipe and his truck just rips.....
 
What Sucks?
Top Speed Low end?
Overall engine performance?
You will need to be more specific.

The tuning could be out of whack, Bad Plug, Wrong gearing, and the list goes on and on.

Give us more details on what it is or isn't doing.

-Ed
 
well its basicaly over all performance. the plug is in pretty good shape, I'm a pretty darn good tuner,(but i could be off, I'm not gonna say I'm 100% right because then id be 100% wrong) the gearing could be off but with this weight and power ratio it should be fine. its 72/20 I'm running a sirio .18 with the stock trx 2.5 air filter(dont start with me i already ordered a motor saver for a .21) and i have a dynamite 1/8 scale sport tuned pipe for a buggy.

oh ya i also ordered a sirio bb pipe so i cane ditch the dynamite.


bbtg
 
With the new filter and the big bore pipe you should be good to go.
 
Originally posted by StrechM
With the new filter and the big bore pipe you should be good to go.
Click to expand...

I'm with Strech on this one. I think the big killer was the 1/8 pipe.
 
It will be interesting to find out.

My vote is YES.

Reason: something to do with lack of back pressure/fuel pressure.
 
could lack of back pressure cause a lean situation??(i know you can have too much back pressure but is such thing as not enuff). cause when i changed the filter it could breathe alot better so i richened it up to make up for the extra air, but no matter how much i richened it(i came out 3 full turns) it was still runnin hotter than hell!! i got up to about 300!! it scared me so i shut it down.


bbtg
 
The big bore pipe is made for the Sirio 18 so I would say yes to the improvement in performance. I can tell you that it made a huge difference when I owned that engine. There is another performce item that you can add that will only cost you a few dollars. Trinity has a 3 shim kit available for the 18. Add one additional thin head shim from the pack and increase the nitro content to 30% if you haven't already done thet. The 18 is so easy to tune that you shouldn't see much of a difference in in the ease of it. You will not have to lean it as much to get more power and that will allow for cooler running conditions.

Can't answere your question about back pressure.
 
Don't know.
Just came to mind so I thought I would throw it out there for someone to comment on. Maybe someone who has tried a 1/8 pipe in this situation before. I haven't. Maybe you are the 1st.
I will be interested to hear what you find out. Let us know.
:radio:
 
the pipe is on the way along with a motor saver filter. I've torn the whole truck, rebuilt the diffs(thanks again 30%), checked the tranny for any binding or just general wear. everything checked out ok and i have the diff and tranny installed again. i cleeaned the engine and checked the whole thing out to see if there was a place i was loosing power, also checked out a-ok. i grabbed a cheapy 2 stage airfilter that breathes just as good as a motor saver, ill just use this till i get my motor saver. now i really just need a pipe and my rrp cb and my check list will be nearing completion. any thing else you guys think i should check??

bbtg
 
Better stuff

I think you should do an 1/8 scale diff conversion, or the aluminium cups ( thats what usuallys fails with huge power) . Also If you want better low end response lighten, replace, or tune your clutch. The easiest would be to tighten your springs(cut about 2mm of the spring then reconnect the spring DON'T CUT TOO MUCH) If you want maxxium performance use the new 1/8 spur and clutch conversion. Then U would have a huge amount of clutch tuning options. :puke: This thing rocks
 
Last edited:
Having the 1/8 pipe that is made for a .21-.27 isn't a good idea to run on the smaller engines. It has to do with the port timing. At least from what I've read, it will throw the exhaust timing off which will allow more fuel to come out of the pipe on the exhaust stroke. The waves of pressure in the pipe/manifold is what keeps the fuel in the cylindar to get the correct combustion timing. If the pressure wave is out of time or to weak, the fuel will just spill into the pipe and whatever is left will burn. This would cause your lean condition. Regardless how rich you make it, the timing in the pipe is still the same.

I had a link that explained it way more thoroughly than I ever could, but what I've put in here is about all I remember.

Basically, using a pipe that isn't designed for the size of engine your using is never good. You will get poor results as you have been dealing with.
 

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