omarwashington

iTrader: (2)

Is this possible? I've always wondered if this is possible. Those on road engines sure are high reving mills.

Jaz240

iTrader: (52)

it is possible but not very practical..you would have to tame it down so much to have any usable power you would just be wasting the added power...on-road cars have much better traction, handling and center of gravity, they benefit from the instant power..in off road all you would likely get is severe tire spinning

Owen RaCing

iTrader: (17)

Ive seen it done. But from what Ive seen, heres the problems.

-Cases are not built to take the punishment of being flipped over, and all the ruff flex from the chassis bent around.

-Cooling heads have less surface area since the on roaders are pushing the air by them so much faster. And they help keep the gravity low.

-Extreme top end, boring bottom. The on roaders carry alot more speed, so in some cases bottom is not even needed.

Its alot of power you really dont need. Powers fun and all, just not always needed. Any of the new top line Off Road .21's will be more than enough

Timmo

iTrader: (16)

I think you will not have enough low end torque to get over your jumps when needed.I mean if you need instant power right then and there when a jump is right around the corner,you won't have the bottom end to push it over with an Onroad engine.

gotspeed_2000

iTrader: (12)

I agree that unless you race on a smooth track without any short run ups, the on road engine wont have the torque to move that the off road engines do. The benefit is that the power band though changed would be wider and smoother. Also the motor will rev alot higher, but also consume more fuel. Can be done, but some draw backs were also stated earlier like the case design not being able to withstand the punishment, surface area of the head, etc. I would go with a good off road engine if possible. I few years back, I seen a guy running a sirio on road engine in his LSP. Tamed the bottom end, and had to change his CB to get max use of the rpm's and powerband. Though it was fast, it sure ate alot of fuel quickly.

houston

iTrader: (96)

you guys are right , we have tested it

the onroad engines are timed different , port heights are way different , all of this changes power delivery . the power is very low on the lower end of the engine .

omarwashington

iTrader: (2)

intresting read guys. I've always wondered now i know

Losi-Runner

I've had first hand experience with this when I got a Rody Mod RB C5 on-road that I stuck in my Losi 1.0. At the time I already knew that on-road engines lack bottom-end so I installed a JP1, Losi clutch with all alu shoes and silver springs (heaviest springs) to get more bottom-end, but still wasn't enough. My local track is a medium size track so I could never stretch the top rpm of the engine. But overall the things was ballistic from mid to top.

houston

iTrader: (96)

PowerHouse

iTrader: (66)

I guess I am trying to defying physics then I am doing some experimenting with some onroad sleeves in offroad engines. I am currently working with the GRP line of engines and have done all the measurements and even though the sleeve port configuration and timing is a little different, I am finding that it is not drastic enough to really affect low end power and in fact I am getting more low end out of them with the added exhaust area. The added exhaust area from the onroad triple exhaust port gives the engine an increase in all around power and the breathability the engine will have, will also help with the fuel milage increases. The transfers are slightly higher than the offroad sleeve but I raise them a little anyway so it ends up being spot on, so basically you could in theory, drop an onroad GRP .21 sleeve in the offroad block and run it without giving up low end and getting more midrange and top end. I can't say this for all onroad engines as I have not tried to make an offroad engine out of every one out there but I have taken a turd of an offroad engine and made it an onroad contender and now I am taking onroad engines and making them offroad contenders. If the port timing isn't what it should be, then you make it what it should be. You have to think outside of the box with this one but I will make it happen and you guys will see the prototypes in Tillsonburg next week. It has already been called the GRP Frankenstein engine I'm not sure why as it look like any other engine from the outside but will be a combination of 3 different engines into one on the inside. I'm even taking the GRP rally engine and making it a Truggy motor next week

razzor

I have done this with a Axe Mamba engine.
swapped internals to a Cobra onroad piston and sleeve after the original piston got damaged.
The motor has enough bottom and feels smoother in its power delivery with strong mid to top end.
Doing the same to my X1 Cobra since i broke the rod overreving it on the starter box by accident.

houston

iTrader: (96)

what was the question again? was it putting an onroad sleeve in an offroad block ? exhaust heighths are different for sure

chunk t

In my 2-wd stadium trucks I like to run an engine with slightly elevated Trans & Exhst port timing. For my driving style I don't want a lot of low-end grunt, I just end up spinning the wheels a lot , so I set my egines soft on the bottom with a strong mid to upper end.