brian_gadgetman

Haven't started the savvy's in over a year. Got into racing oval and forgot where the real fun is.

Been outa the loop for awhile,but noticed on youtube some guys are starting to drop 4 strokes in their trucks. Seen an LST with a .70 in it. Sounded badazz,and looked to be about the right power/weight ratio for the drivetrain. Anyone here into that? Curious as to the clutch and gear ratio setup.

The LST was running a fan to help with cooling on his OS .70

rcracer126

I had an OS .26 four stroke in my nitro mt for a while. It was a good engine, but definitely needs a fan or some other device to cool it.

Pros: lots of low end power, longer lasting with proper cooling, sweet deep sound, unique
Cons: requires a conversion kit and possibly some modifications, requires extra cooling, only reaches about half the rpm of 2-strokes, needs valve timing adjustments after a while, would require a gear ratio change to perform the same as a 2 stroke

In my opinion, I would stick with a 2 stroke because of the good power across the whole powerband and the ease of use(doesn't require extra cooling or major gear ratio changes). And yes, it would require a bigger clutch bell or smaller spur gear to make up for the loss of rpm.

I did have some problems with mine, but if set up properly with a conversion kit, gear ratio change, and extra cooling, it could definitely work very well and can be a very fun project to take on.

rcnitrohead

gonzobot on the Traxxas forum is in the middle of dropping a 4-stroke in a T-maxx. I'm bidding on a Saito 56 on the bay to drop in a Camaro project, I think I know the guy you are talking about. He mounted his engine the "wrong" way and had a cover over the fan with a geartrain going under the crank case? I spoke to that dude, good stuff. I would elaborate a little more but I need my sleep

gonzobot

here's my work in progress. Im not finished it yet, but i can tell you one thing gear high

brian_gadgetman

There ya go Gonzo, lil RC'er enginuity. [8D]

It'd be more of a project truck. Have another to keep a nitro in. The cons would far out weigh the pros, but what the he!! it's a hobby right?

Not sure if I'd say the 4stroke has more low end. Hear that a lot. Per cu. in. the nitro 2 stroke aughta smoke it across the board,they hit the powerband like flipping a switch. Have had nitro 28's that ate HD bones for lunch. I'd call it a smoother more gradual power. It's my guess that a guy can get away with more HP from a 4stroke on the same drivetrain. But, it also takes more cubes to make the same power,now we're talking a big motor. Clutch bell and spur matching might be tuff,especially with a bigger crank.

It'll be heavier, a peta to get the big stroker to fit, perform at a bashers level, and not cheap. It's that sweet sound,Baby!

brian_gadgetman

Here's the LST nitrohead and I seen. Looks like some serious gearcase going on there,but can't see it very well. I have an extended chassis,but thats a huge motor to get in there. It'd have to mount the right direction in a savvy. [link=http://www.youtube.com/watch?v=w5wsfHdTcdA&feature=related]4stroke FS70 LST2[/link]

Here's a twin 40's 4stroke savvy that sounds sweet,with decent power. But it looks like he butchered his plates to get them in. [link=http://www.youtube.com/watch?v=ioGFZEAa90A]twin FS40 savage[/link]

Urbandrag

http://www.youtube.com/watch?v=ioGFZEAa90A Found this few hours ago...

gonzobot

nice vids cant wait to finish myn. here a bunch of pics i managed to dig up cause thats what we want right? pics and vids




lol rotary engine








i have a little too much time on my hands lol

rc-sport

My Feedback: (12)

Now this sommething I'd be very interested in. I'm a plane guy and I only use 4 strokes, can't stand the noise of a 2 stroke. When I first started my Savage XL I almost went into convulsions, it was like finger nails on a blackboard. Converting my XL into a 4 stroke would make me very happy. Are there kits out there that I could get for this?

black mamba

LOL. A guy I work with is a huge airplane RC'er and he wants me to stick a big ol 4 gun in my Savage. I think it would be cool because I like big engines, but I'd go 1/5 scale gasser before I did that.[8D]

rcnitrohead

Yeah Brian, looks like we were thinking the same way about that vid. Here is the info that guy gave me a LONG time ago

http://lcgl.se/pics/st.jpg
http://lcgl.se/pics/m4t.jpg
http://lcgl.se/pics/lstm.jpg
http://lcgl.se/pics/Fsida.jpg
http://lcgl.se/pics/flackt.jpg

Some Info
On the pics you see that the engine is turned 180 degres so its easy to start with my modelplan starter and its gear up the clutch so i can use the standard clutch and standard gear ratio...
Its has also a 4 blade fan like the helicopters so no heat problems.
The only negative on this setup is that a big motor is needed....lots of rotating masses on cogwheel.
But it works perfectly.
The run time is about the same as before.

Hope it helps you..

Christer

Hope he doesn't mind too much in case he sees this,

Tom.

brian_gadgetman

mamba, when HPI comes out with a 4wheel drive version of that 1/5 scale stadium, I'm in. Have a bud with the buggy all tricked out, one bad toy! Imagine a 4 wheel drive version of that with a 35cc tuned gasser. Prolly be a $1600 RTR with that much in hop ups to trick it out. I can start with the savvy 1st.

Sport, haven't heard of a conversion,but bet it's in the works somewhere. I think Christer's got it figured out tho. The gear increase case he made aught to work in the savage chassis. Basically a 1 to 2 gear increase on a special turned shaft,that'll accept the gear on one end and the flywheel/clutchbell on the other. The case only really needs to be a plate with pillow blocks to hold the sealed bearings. Extend that same shaft out farther,mount a pulley behind the gear,and you could belt drive a small fan. Might be able to talk a guy I know into turning this. Need to find all the parts and start spec'ing this out.

Good find nitrohead, [8D]

brian_gadgetman

Do think the brass gears he was using aught to be nylon tho,or a rock could end your day with a busted crank. It'd be quiter too. Suppose it could be done with a shear pin. hmmm

Gonzo, you know who's savage that was?

mrblah

I've got a .40 powered t-maxx

they run HOT, I still have not found a proper keyed flywheel, if anyone knows where I can get one, it would help my truck a LOT, the collets slip when it backfires or starts

rcnitrohead

Hey mrblah thats awesome, got any pics or vids? Could you share some insight on how you start it, also is the compression significantly higher than our 2-strokers? Thanks.

Brian- I've got no clue about those gears, but his LST2 seems to be moving pretty nicely and it looks like he has it all figured out. I wish some guy could make a drop in clutch for plane to car conversions on these thumpers. Gonzo grinded down his shaft and it accepts our 2 stroke clutches and another great guy here has told me to look around for helicopter clutches which look weird to me.

I just placed a bid on a Saito 56, hopefully I score one of the engines on ebay right now, I really need to make more progress with my build.

Tom.

mrblah

it's a pull start, you have to use string from a hunting store, ie bow string, or it'll break, I use the kevlar stuff, very high compression

rcnitrohead

Ooh, now you've definitely got to post pics at some point!. So you'd say that a 500 size electric motor wouldn't be able to spin the engine? Did the 40 come as a P/S unit or did you fabricate something? Thanks,

Tom.

mrblah

it came with a pull start, it's the standard os .40 pull start engine, I dont think they make it anymore, they had a .26 version too

rcnitrohead

Ah its the car version, clears that up.

mrblah

yeah they were made for cars/trucks

ilmoriggia

Hi rcnitrohead i'm Claudio end i write from italy nice to meet you ...sorry for my bad english but i sse your project and for me is very intersting because i have a problem with my savage with a saito 82.
Dont't starting because i think the problem is the flywell too much small .. yoc can help me for this problem.. i laike very much your work!! complimets!!
this is my work:


thanks very much
Claudio

ilmoriggia

Yes is for car and you can see the my first project www.tonymodels.it and clik the link over savage 4 stroke and i have used the O.S. 40FX four stroke
I hane doing a trial race and i need more torque a low revs .
this my pics:

rcnitrohead

Hi Claudio that looks great! I think you are mixing me up with one of the guy here, I have barely started the mechanical aspect of my project and am still waiting for parts to come in. I'm sure one of the great guys here can help you.

I think if your flywheel was too small the engine would still run, are you sure you have it primed and everything is set? I would think it would still run at least for a few seconds before popping/backfiring on improper settings. Good luck to you and your project, it looks excellent!