Maxx max speed?

[Maxxbash]

sorry if this topic has already been addressed before, I searched and didnt come up with anything.

can a stock maxx really top out at 40 mph out of the box? if so I have a problem, I just got the Sirio .18 and BB pipe on my truck running a turbo plug and trinity monster brew 20%, all of the gears are stock, I borrowed a very small light weight GPS which records the max speed and secured it to my max, the highest recorded speed was 32mph, I know the GPS is accurate cuz I tried it out while driving and it recorded the same as the speedo in my car, needless to say I'm concerned, the truck sure seems faster with the sirio but I was never able to use the gps with the 2.5 engine so I dont know what it maxed out at before, I made sure to break in the sirio properly and I'm still learning the finner points of tunning it as its margin for error is very small, but once its perfectly tuned it should be able to get it past the 40mph mark without having to regear the truck right? or at least I hope, maybe I'm not tuning it properly, any suggestions on tuning the sirio?

I realize the maxx was not designed or built for speed and I sure didnt buy it or use it for speed, but it would be nice to know that after dropping the cash for the new engine and pipe I could beat a stock maxx in a race!

 

[Rolex]

I really don't think it will do 40 out of the box, but you got a good engine with the sirio. Have you changed the spur gear, or is it the stock 72 tooth. If you want better speed, and still be able to handle it on a track, go for the 70. It made a great difference in mine on a straightaway. If you're looking for mostly speed, go for the 66 tooth.
Accurate carb tuning is also the key to good high end performance.

 

[akmadmaxx]

I 2nd that motor it is awsome! good pick!

 

[El Pirata]

I'm here to bash a GPS in terms of both checking your speed and also your heading. While a GPS is great there's a thing called "selective availability" (SA) that the Department Of Defense, who owns almost all the GPS satalites used in the world, has put into a satalite programing. SA is a safety feature that helps prevent someone from grabbing the GPS signal and using that to shoot to the coordinates that the GPS is displaying. SA can be anything from 0 - 200 meters off. 9 times out of 10 your coordinates and information that your GPS is displaying is trying to determine whether SA is on or off but it also makes the information very sketchy. If you really want to check your speed accuarately I would recommend a radar gun or using a stopwatch and a known distance. Just my $.02

 

[Tarant]

With my maxx I got to 37.7 mph useing blue thunder and the TRX 2.5 and all stock gears.I know its accurate because I used a gps and I drove it on a flat open field for about100 yards and I also used the 60 ft tech. were you have a freind start and stop a stopwatch and the average was 37.7 mph.

 

[Maxxbash]

is it really necessary to seal the carb and back plate with silicone? and has anyone tried cutting the header? does it improve performance?

 

[olds97_lss]

Sealing the carb and backplate is more like preventive maintenance. It will definitly help prevent air leaks. Some engines are more prone to leaking while others aren't.

Before installing any new engine I buy, I tear it apart, flush the inside out with alchohol and a q-tip to get any aluminum bits out from the milling process (you'd be surprised at how much is in there). Then after all is dry, I seal the carb and backplate.

If your having erratic tuning issues, it's more than likely a leak somewhere. Doing this on the engine prior to installing it helps narrow air leaks down to fuel line, fuel tank and filter.

As for cutting the header, what do you mean? Shortening it or rounding out the hole some? I've done it on headers that fit onto a side exhaust engine, but not on a rear exhaust. On side exhaust rectangular exhaust manifolds, the hole in the manifold rarely is as big as the hole in the crank case. Opening that hole up in the manifold helps in that case. But if the hole in the manifold is the same size as the hole in the crank case, I couldn't see much, if any benifit from messing with it. Just my .02

 

[Maxxbash]

I was browsing Trinity's web site and found a "speed tip" which recomends cutting the header back 3/8” to get the most performance out of the Sirio .18

http://www.teamtrinity.com/nitro/engines/sirio/sirio.asp

Below are some tips to get the MOST performance out of your Sirio TX-18. Let the wheelies begin.

Performance Settings for Sirio Performance Pipe


Header: Cut 3/8” back
Ambient temp: 32-40F (yeah.. it's cold in Jersey!)
Plug:
Standard: Nova Rossi #C6
Turbo: Nova Rossi # C6TGC
Mid Range: Fixed
High End Needle: 7-1/4 to 7-1/2
Low End Needle:1-1/2
Fuel: Trinity Power Blend 20% (MH0020 Qts / MH4020 Gallons)
Head Shims: Standard (1 thick/1 thin)
Receiver pack: Trinity #5304 5 cell (Needs female end to be soldered)

under the tech tip area I found the following:

Rule of thumb:
Longer manifold = more bottom end torque. [At the expense of some rpm]
Shorter manifold = more top end rpm [at the expense of some torque]
BUT you can go to far with either direction causing the engine to run erratic or HOT!
You must keep it in the "sweet spot"
Bottom line: there is no set length for every engine or pipe, experiment with the length to suit your driving style or track needs.

I was just wondering if any one has tried this?