ORIGINAL: iexion
ORIGINAL: 1QwkSport2.5r
ORIGINAL: iexion
Gearing also helps. If anything thats the first thing you'll want to change out before trying a new engine
Trying to make an LST go fast is going to take more than just regearing it. These things are pigs and it takes a copious amount of power to get them moving fast. A
good engine is a must, swapping out for the tallest clutch and spur combo available, and then using the transmission gears from the Brushless conversion kit to be stupid fast (for an MT) and FOC kit.
This would be the way I'd go if I wanted to build an LST for speed. The Mach .26 will get it moving decent, but if top speed is the objective (and it is) then that engine wont cut the mustard. A very good .28 or .30 will be needed.
Depending on what .28+ BB engine you get. The bigger the cc the less top-end they tend to have (unless you have a $200+ high end engine). To compensate for the bottom end torque you get with a bigger cc engine you change the gearing. (kinda why you might put a higher tooth clutch bell on a buggy with a .28 engine)
Example: Axial .28 Spec 1 is a bottom end engine with little to nothing for top end. Mach 26.SS however has greater top end but wouldn't get anywhere off the line over a .28
Axial .28 Spc1 Bottom end
Mach .26SS Mid-Top
Mach 427 Bottom-Mid and still has more top end then the .28 Spc1
Point being, bigger doesn't always mean faster and just because you slap in a .30 doesn't mean squat. If your gearing is stock a bigger engine will get you to your gearings top end a little faster.
Yes im aware of what kind of energy is needed to move a LST (still have pictures of my .28 Axial then Mach 427 then Picco .28 Aftershock on my profile)
LRP z.28 is one of the engine most people buy when they want ''real'' power without spending over $200. Not sure if losi's 454 and the z28 are the same engine inside[:-]
An electric conversion kit + single speed gearing + Forward Only Conversion + ESC&Motor& the Batteries to power it = well into $400-$500 range (more then a high end engine)
First off, displacement has nothing to do with if the engine makes more top end power or bottom end power. The biggest factors that influence the powerband are the number of ports, the size of the ports, the timing of the ports, the size and shape of the crank port, the size of the crank induction channel, the compression ratio, and on and on and on. Whats more, the exhaust has a big influence on where the power is generated also. You can have two identical .28 engines side by side with two completely different exhaust systems and see a major difference in how they perform. The trapped compression ratio along with exhaust timing would be a dead giveaway as to where the engine will make its best power. Even more; You could put a 3-port engine with larger ports and better timing against a 6 port engine with more smaller ports and the 3-port could very well outperform the 6 port engine. Generally, more ports means more top end but that isnt always the case. The M26SS engine uses a high compression head button (same head button the Teal Mach 427 uses) and 3 port sleeve. I dont know the port timings for that engine off hand, but the one I had was far better down low then any of my Mach 427 engines using the same fuel and exhaust. My teal 427 was stolen before I could ever get it broke in and really opened up, sadly.
The LRP .28 spec 3 and the 454 have the same bore, stroke, carburetor, number of ports... but again, I dont have either to check the port timing to know if they're timed the same or not. They're made by the same factory, so its very possible the only differences are cosmetic.
As far as electric conversion - I never said anything about converting to electric. The Losi Brushless conversion kit has different transmission gears with (IIRC) more teeth than the stock LST/LST2/AFT transmission gears. The XXL has 1 tooth more than the stock LST/LST2/AFT, and the BL gears have 1 more tooth than the XXL gears. If you have an engine that makes enough high end torque, an LST with the BL gears (and if there's room, do the gear flip mod), Max spur/clutch ratio, and low profile road tires, you would have a faster LST than if you had a stock .26 geared to the max only. Yes, you might get more speed just by regearing... BUT to get more speed, you need to add more power, and more gears to take advantage of the power. In order to add more power, one almost always needs to add displacement.
The problem with RTR engines is they are not timed as well as the high end race engines. They will not turn the rpm a good high-end engine will. What I meant by a
good engine is one that is timed and ported to make top end power, and lots of it.
I'm not questioning your logic, but I will say speed costs money and a RTR sport engine is not going to produce the gusto needed to go that much faster even with the best gearing possible. They just run out of steam. IMO, all of the engines you listed among many others, are just that. Sport engines. They are sub-$200 engines that anyone can break-in and run and get decent performance from. They are not anything close to a Novarossi, Picco, JL, etc. in top end performance.