guyelcamino

I have a Firestorm and have enjoyed it, WHEN IT RUNS GOOD! It has taken a beating and the truck is tough with almost no breakage to the body/chasis/suspension. Now the motor on the other hand has been giving me trouble. I have had clutch problems, throttle return issues (the ball and cup were to tight from the factory and was binding, I sanded off the paint on the ball and works fine) and the spring in the crank that holds the drive pin for starting broke after only a few tanks of gas.
I have put about 1 1/2 gallons though the motor and it will not tune and run properly. It's time for a new one. Don't like the composite (plastic) carb either.
I want to put an O.S. engine in but can't find a direct fit. Would like to stay with a .18 but I am open to other options. I talked to O.S. but they were not much help. Original HPI motor has a rotory carb, side exhuast, sg style crank, and I installed a roto start. I would like to make the minimal amout of modifications as possible. I'm willing to change exhuast to rear exit but don't want to give up my roto start.
Who out there has done this swap and or has any info and suggestions?

5810

Hey i would go with a os 18 cvr motor, Its an awesome motor for under 100 bucks, starts every time. I have it in my rush, with 47-19 gearing & that thing screams. you will need some engine mounts & it should be a straight swap.

Gereke

OS .18 CV-RX will work in a firestorm as well, however it requires that you trim down the crank about 1/4 inch and use an adapter nut for the clutch bell.

gflyer_22040

os.18cvrx w/11j rotary carb its a great engine u just need a new backplate i suggest the duratrax kwik pit supperstart one u can usually find all this on ebay or youre local hobby shop

guyelcamino

Ok I finally completed the engine swap so hear is all the info to do it.

O.S. 18CV-RX 11J ABC engine p/n OSMG2104 or 11880 Tower Hobbies p/n LXGGP7
HPI Pilot Shaft M5 p/n A805 Tower Hobbies p/n LXM720
Duratrax Super Start Backplate p/n DTX6031 Tower Hobbies p/n LXHPS2 (this is optoinal if you hate pullstarts)
Team Assosioated Carb Return Spring p/n 7562 Tower Hobbies p/n LXUP98 (optional but would recommend it even
with the original motor)

The O.S. motor is a ROTORY CARB with SIDE EXHUAST just like the original HPI motor. It comes with a pullstart which means the back of the motor will except the Duratrax Super Start adapter. Non pullstart motors have a different back and therefore a different bolt pattern.

The Modifications I had to do to install it were to cut about 3/16 (.187) off the crankshaft so the HPI pilot shaft would screw on all the way. Yes thats right cut the end of the crank on the new motor you just spent over $100 bucks on!!! I was'nt to happy about the thought of it myself. A cut off wheel in a dremel made it a piece of cake. The shaft is hardend and I didnt have to dress the end of the threads much to remove any burrs. Don't buy the Team Assosiated clutch nut that I saw recommended in the other forum. The snout is to long.

The original motor mounts will work if you file or dremel clearance in them. The back of the O.S. motor were the bolts for the pullsart go interfear with the mounts. They are soft aluminum and were no problem to file. You do not need to use the motor mount spacers supplied with the O.S. motor or buy the HPI 20mm purple engine mounts either. They don't fit the Firestorm chasis so don't waist $20 like I did.

You will need to cut the bottom chasis plate. The back of the O.S. motor is larger then the original HPI motor and hits when you try to bolt it down. You have to cut right up to the mounting holes for the motor mounts in the chasis. You can cut it all the way across with a cut off wheel even though I just cut a notch for the back of the motor. You may need to trim a few threads off of the scews for the pullstart/Super Start if they protrude through the back plate.

The original exhuast will bolt up but you need to cut the bolts down to 25-26mm (1 inch long) or buy shorter ones. They will hit the header pipe when you tighten them all the way.

I chose to rotate the carb slightly so I could get to the LSN. If you turn the carb to much the throttle lever will contact the head. Especially since it is plastic and deflects under full braking. I also added a Team Associated throttle return spring to asure full throttle return to idle. I had problems with the original motor not always returning all the way and driving me nuts trying to figure it out.

I have just finished bolting it up and have not yet broken it in to work out any possible bugs or give any porformance data. I did port my exhuast header and tightend up the servo saver so the car will finally turn. My next upgrade will be a Hitech 645 servo for the stearing.

guyelcamino

Well I got to break in the O.S. engine today. I used the heat cycle method. I had a hard time starting it and when I did it would'nt idle. She was PIG RICH from the factory. I had to lean out the LSN to get her to idle. When I ran the car it had those gargling sounds due to a super rich HSN setting and was limited in rpm's. Once I started leaning that out she woke up. I never got her over 210 deg. so I know my settings were safe and I always saw a trail of smoke. I guess I'm still used to the original G3.0 settings. The manual for the O.S. motor has different high and low speed needle settings by a few turns. Made me a little nervous at first thinking everything was going to be to lean until I was spurting raw fuel out the exhuast. I haven't got a chance to fine tune the engine yet to evaluate it's performance though.

guyelcamino

This engine rips!!! I have pro line m2 gladiator tires on the rear and I can't keep the front wheels on the ground when running in grass. I have the 21 tooth clutch bell , slipper clutch turned 6 turns out ( factory spec) and tunned slightly rich. It has pick up like a bat out of hell. My street tires aren't that sticky so the rear end kicks sideways when I take off. When I do get a good bite on the street I have to let off to keep in under control.

Nesal

Hey nice one man! looks pretty cool!

standupclothing

WELL i was wandering what happened here... I cut my shaft 3/16" off and then removed the friction plate that came with the motor, placed the flywheel collet over the square key, put flywheel on the collet, put the clutch shoes on, screwed in the pilot shaft, put a washer then bearing then clutch bell on the pilot shaft and screwed that on with the bearing and 4 washers. My problem is that the clutch bell tightens up against the flywheel... isn't it supposed to spin freely?? Did I put it on in the wrong order??

Thanks!

NitroNate

Which CV-R do you have??(S) or just the standard CV-RX?

standupclothing

The standard one...

NitroNate

Hmmmm,I never encountered such a problem.Are you sure its against the flywheel?If you over-tighten the clutch bell screw,it will have quite a bit of resistence.I put the collet and the flywheel on,then the pilot shaft,then the shoes,then the CB.Other than that I couldn't guess what the prob is.[&o]

standupclothing

ah thanks nate but i got it! it was all those dang washers that came off the g3.0... they wouldn't let the bearings spin so i just put three before the screw head and it works perfectly and i was able to complete mounting the motor tonight :-) just gotta get a z-connector extension for the new receiver and i will be ready for break in... oh yeah and should i get a new exhaust gasket probably? the paper one was junk after taking the header off...

standupclothing

well i got it in and everything all together... i will post pictures when i get home tonight if i remember... what do you guys recommend for break in? what is the normal running temp for this thing?

NitroNate

I always use a Heat Cycling Method.The temps should run like any other nitro engine,210-230*F.

MORE SPEED

Sorry to bring back an old thread, but my OS came about 1 1/2 turns off from factory. It took me ages to find out. It made me look like a noob.

MORE SPEED

NitroNate

So did mine...The peak running temp,without messing with the needles,was 115*!LOL! RICH!So rich fuel shot out of the stinger.

fokaid

Special thanks to all who have posted and replied about the O.S. engine swaps my Firestorm is finally done. Just finished putting it together at 9:00pm. I will be breaking in the motor tomorrow after work, and will post some feedback and maybe have a vid. I would like to thank those who have gone above and beyond to venture out and find out the hard way as to what works and what doesnt.

fokaid

By the way, this was my first nitro rc and engine swap. I guess you can call me a noob. LOL

tonydig11

I just installed the CV-RX in my RS4 evo. It was rich by almost a full turn. once i got that figured out the breakin went smoothly. I wonder why these motors come so rich.

standupclothing

Ah thanks to all the nice advice I got mine in a while ago, just recently tuned it and yes, it is nuts.

Wheelies with a pull of the throttle at almost any speed, crazy fast and only running at 220 degrees right now [8D]

Very happy with the results, although i have to admit i ate a clutch during break in

bao

I know its an old thread but i thought i would revive it as i am waiting on an os 18 cv rx to be delivered for a firestorm i have.
First of all does any one have a running vid of the firestorm with this engine installed ?
Second has any one encountered any gearbox/diff woes with this engine ? I have stripped cleaned the gearbox and rebuilt the diff with 30k and i must say im quite impressed with the solid look of it all (full steel)
Im used to running bigger models but i must say i have great fun with this little 2 wheel drive model.