10th Scale 4-stroke Sprint Car

[JoeDirt]

any chance you can post more pics of that 4- stroke sprinter on the front page? been interested in building a 4 stroke car. thanks

[Doug Carter]

That car was built by Randy Hobena, based on a CW chassis with a CRD gas conversion. Easily one of the coolest gas 10th sprint cars I have ever seen run. I'm a torque freak, and this thing had GOBS of it. Not only that, it sounded BAD ASS.

I have some more photos of it at home in my archives. I will post what I have later today. Maybe if Randy is lurking around he can chime in on what he did for that setup.

I still want one of my own.



d

[Doug Carter]

Just to let you know, I am still obsessed with this particular car, almost 3 years later. These photos were taken at a weekly gas show at Monee Raceway, in Monee, Illinois. The car is owned and built by Randy Hobena out of Wisconsin. IT is a CRD/Custom Works-based car, using an OS .26 4-stroke motor, with a hand-made exhaust system. For what it's worth, OS now makes a slightly larger .30-sized airplane 4-stroke that includes a pipe and a muffler.

Randy, are you lurking out there?

I still want to build one of these, myself, but without any legality at any races, it may not happen anytime soon. Who knows, though, the 4-strokes made their way into the AMA Supercross series, why not here? One more rules issue for Craig to deal with, right? :D

[hawgmaster]

Hey guys,
I am running the 4 strokes in two of my cars. I have a OS.26-car in my NTC3 and it runs great, it has so much torque that the car wheeelies coming out of the turns sometimes.
I also have a OS.40-C in one of my 1/8 sclae latemodel cars. with a 20 tooth clutch bell I am getting 42 mph out of it, I now have a 22 tooth bell on it but I have not GPS'ed it yet to see what the speed is. The coolest thing about the 4 stroke is the sound, it is cool as crap.

I have to say, that sprint car looks awesome with a 4 stroker in it, congrats to the builder on a great looking ride.

On a sad note however, OS has discontinued the OS car motors here in the states. you can still get the .26 1/10 sacale size one from over seas , but the .40 1/8 scale size one is gone for good. Every once in a while you can find one on Ebay, so if you are interested in trying one of these motors keep looking on ebay, expest to pay about $200.00 to $300.00 for one in good or like new shape..................Todd

[nightowl75]

That appears to be direct drive. Is that the gas tank on the right rear?

Richard

[Jeff Harper]

That is really cool. Why the expansion chamber on the four stoke?

[Doug Carter]

That appears to be direct drive. Is that the gas tank on the right rear?

The car is laidout exactly like the CRD 2-stroke kit, with the gas tank in the front of the car. It is based on the exact same tranny/diff setup as the normal CRD kits. I believe that Randy just figured out the fit and mounts for the motor, and got the alignment correct with it, and it bolted right up. If I remember correctly, the only real problems he had with the build was the exhuast. If you look closely, the exhuast header coming out of the motor to the stock CRD Wolfie pipe is a bit extensive.

Todd, are you aware of the current OS Surpass lines for airplanes? I believe this motor was an air motor, and not made for cars, too. They appear to still be in production...

http://www.osengines.com/engines/surpass.html

I'd love to know, because I've got the gears turning again. I think I found a purpose for my second sprint car. :o



[EDIT: I just found the discontinued car versions of these motors that Todd was talking about. It looks like they were only black cases, but not much visual difference between the airplane versions. Gonna have to do some more research. Now that I'm looking at the photos of Randy's car, it appears as though it is the black head/case version, which probably makes it a .26 and not a .40 4-stroke.]

[JoeDirt]

thanks for posting some more pics doug. i tryed to get my local track to let us run them......they quickly said no. the 40 only has .69 hp according to O.S, but the torque is unreal. the four strokes have taking over supercross pretty much and ive ridden one and was the reason why i wanted to try a O.S in a gas car. is that a crd conversion he used? would be cool seeing one of these line up against the 2 strokers. thanks again

[Doug Carter]

I saw this car run against the reguar 2-stroke cars, and it was VERY competitive. It was definitely a torque monster. It would be a great car on high traction short tracks or races with a lot of traffic to sort through. If they were legalized for regular competition, I would definitely build one.

I may build one, anyway. :D

[Doug Carter]

Ok, a couple of phone calls later, I found out that yes, the FS-26C has been discontinued.

However, it was discontinued because it is being replaced with this (http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXJRW8&P=0), due here in the US in limited numbers later this month.


:D


Man, I wish my wallet could keep up with the speed of my brain. ;)

[aceedmonds]

cool pics I remember the car but its cool to see the pics again, I can see the wheel stands it did down the back stretch at Monee

[DirtFords1]

This thread is great, I recall car-action/Steve Pond did a couple 4-stroke set-ups with the GT truck,and a Kyosho TC.He had got ahold of some parts and stuff from Form Racing of Japan.
The accessories were a 2-speed set-up and exhaust system for the TC.He also had a special intake manifold for the car custom made to run it parallel to the chassis,as the stock one sticks out to the side alot,in harms way.But.............as OS discontinued the motors awhile ago,i never bothered to go any further.If anyone remembers Wolfpack originals' parts from NYC. He made the intakes for the 4-stokes on a custom order basis.I don't even know if he still does RC parts anymore.If anyone is curious,I still beleive that Form Racings' site is still up, try these:

www.form-racing.net (http://www.form-racing.net/) or www.formracing.net (http://www.formracing.net/)

I'd throw a 4-stroke in one of my cars if I knew of some clutch and flywheel parts were available.Keep this thread going,I'd be real interested to see what goodies come up!!
Thanks fellas! :D

Doug,At this point in time,so what about legality issues with the 4-strokes,if you got 3 or 4 of 'em "at" the track, I'd venture to say that the man would let you run 'em!! "Exhibition Class"
always gets their attention.Man!! I wish alot of us lived closer together.LOL Doug,I got the same Wallet /Brain issue goin on too.Fear not my brother!! YOU ARE NOT ALONE :skull:

[RichA]

Doug

Can you tell me who is the Mfg of the pipe that you have on your sprint

Thanks

[Doug Carter]

The pipe on my old sprint car in my avatar and profile photo is the same pipe on Randy's 4-stroke above, made by CRD (http://www.dirtoval.com/crd). It is called a "Wolfie" pipe, and it works pretty well. It is a bit awkward sometimes to fit on the left side of a sprinter, but it can be shoved in there.

[shoemaker]

I remember when one of the owners of a Moody American here in Rochester, NY had a 40 os 4- stroke in the front of his 1/8 sprinter and the car would pull the front off the wheels any time he punched the throttle. And that was with Foams on the rear here at Mod Stock Raceway. He had machined dual exhaust headers running out both sides. I wish I still had a picture of this car. I wish some one would bring back the Moody American again in the complete kit form that once was available. I am sure Roy would be glad to work with someone to produce these cars again.

[IRON LOU]

Hey doug,are 4-stroke model motors like motorcycle 4-strokes? Do the last longer than the 2-strokes? Do they have oil in the crankcases like a regular 4-stroke? Do they use nitro,or gas? Any Castor?

[Doug Carter]

Lou, in my research, they run on the exact same nitro, but prefer a synthetic blend with at least a 15% oil blend. They don't like castor or dino-oils because they tend to gum up all of the many moving parts of a 4-stroke. Oil is in the fuel, like all other glow engines. They do appear to be very similar to motorcycle 4-strokes, in that they last longer, are easier to tune, get LOTS better milage, and produce a ton more torque. Geared correctly, they should be able to run with a two-cycle at most tracks. Plus, they sound WAY cooler than a 2-stroke. The deep thump of even a tiny 4-stroke is awesome.

Downsides are, you have to adjust valve lash (I have no idea how yet), there are a lot of moving parts, and they are more expensive to buy intitially. I would argue that if the lifecycle is double that of a 2-stroke, and the cost is double, it all evens out in the wash. One big downside I see, is the availability, though we should be seeing the new version of the motor listed previously in this thread very soon in this country.

There are a couple of guys in this country doing some very interesting work with the small 4-stroke OS motors, like titanium valves, ported heads, custom exhausts, etc. The initial tests on these things when lightly worked over is jaw-dropping. I think with some minor custom parts, to adapt 5mm Associate clutch systems (single and two-speed) to the 1/4-28 crank shaft thread, and a bit of carb and exhaust experimentation, this could be a failry straightforward build.

What do you say, Lou, you gonna build a weedwhacker sprinter with me? :D I'm putting the car together in my head right now, tring to figure out the logistics and necessary parts to seek out. I think I'll work with Chad at Dynotech to develop a chassis/motor mount layout that fits it directly, to make things easier. Wouldn't it be nice to buy a 4-stroke-ready gas conversion kit?


d

[IRON LOU]

Gotta say,I'm intrigued!!! Actually,when I said castor,I was kinda talking about lube in the fuel in general.I always wondered why 4-strokes weren't more popular to begin with.I see guys getting a gallon or only slightly more from some motors.Setting lash is pretty easy,I'll bet they're set at zero,most air cooled pushrod motors are.Are you supposed to run expansion chambers with them?? I'd bet a 4-stroke airplane muffler would make even more torque,and take up a lot less room.You might even be able to run it out the back.I'd like to build one,but I doubt most of the other guys around here would.I don't get to race nitro much as it is.

[aceedmonds]

hay Doug I was talking to Randy Saterday he said he still has 4 of those motors and plans to put together another stroker car .Any thing he comes up with is cool

[hawgmaster]

Hey guys,
the four stroke car motors are diffrerent from the plane 4 strokes, they have bigger valves in the heads, more compreesion, bigger lift cams and stronger valve springs. the plane 4 strokes turn up to about 12,000 rpm, the .26 car 4 stroke turns 20,000 stock and with some mods they will spin up to 26,000 to 27,000 rpm.
OS makes a little valve lash kit that has 2 feeler gauges and a wrench and allen wrench, the motors do need a little lash becauise the engines do not grow that much with heat like a lot of bigger four strokes, when I drag raced volkswagons I set the lash on those engines at 0*
and when the motor got hot I had .011" vlave lash.
These OS motors have so much over lap on the cams that they do indeed get some benifit from running a expansion chamber to reflect the exhaust wave back towards the head before the exhaust valve closes.
The are competitve with 2 strokes if you gear them correctly, the .26 I have in NTC3 is awesome, I was running it at a little dirt oval track and needed a lot of gear. what I ended up with was a RC10GT 64 tooth spur gear, I had to open the middle up to fit the NTC3 spur gear mount but it works great. I come out of the corners and punch the throttle and the car will carry the front end a long way down the straight.
The .40 in my 1/8 scale is currentl pulling a 20 tooth clutch bell and a 51 tooth spur.
I have just got in today a 21 and 22 tooth CB to try this week, I am going to race it this coming weekend at the local track against the 2 strokes.

[IRON LOU]

If an expansion chamber works because of big overlap,it would probably be worth experimenting with different length straight pipes.The straight pipe would give a little better scavenging at bottom end,and still give a little reversion at high revs.

[mikejhs82]

Here guys is a link to a website selling ASP motors. They have a 30 size motor. It appears to be an OS clone. I have one of their bigger plane motors a 91, it is a reliable power plant.
Best yet the 30 4 stroke lists for 79.99. at thia price there is gonna be a lot of 4 stroke sprints out there.. lol


http://www.justengines.unseen.org/


Have a great day !!!!

[mikejhs82]

While I was hunting around. I found another link for a small 4 stroke. Saito (airplane guys know this name well) has a 30 4 stroke. Sells for $165. go to this site to check out the specs.


http://www.horizonhobby.com/Shop/ByCategory/Product/Default.aspx?ProdID=SAIE030S

[Doug Carter]

As the point was brought up earlier, a 12,000 RPM airplane motor poses some serious gearing problems with this typ of conversion. I'd love to see a commonly available engine for this type of car, because I'd be at the front of the line, spearheading the charge to 4-stroke dirt cars. One of the biggest issues for the 4-stroke motors though, seems to be gearing. As it is, a motor producing 25,000 RPM like the car version of the OS lineup, you're right on the cusp of available gears anyway, without using 2-speed clutchbells.

In my research, there are some guys building replicas (or replacements) of the FS26S-C by buying an FS30, an FS26S-C cam and valve springs, the .40C intake manifold, then installing your favorite 2-needle carb. The parts list churns out a motor with larger displacement and relatively similar costs to the now discontinued FS26S-C.

There is some interesting stuff out there for these, but it's very difficult to find much. The motors themselves are very difficult to find in the "car" format, but as it was stated before, the guys using them are generally getting them from Japan.

I talked to someone this afternoon about the OS FS26S-C II that is supposed to be here by the end of this month (accoring to Tower and a few other dealers), and they said they are already being sold in Japan, and no one knows if they will ever be imported here at all. I guess OS and the importers think that adding more versions of their .12 and .15 lumps are better items to stock and sell than anything interesting like a 4-stroke.

If this or any other usable engine was more commonly available, I'd be drawing up plans to develop a full on conversion kit for dirt cars. I just don't know if the hassle to find the motors is going to be something that anyone will want to undertake. :(


d

[driver2b]

The current rules at my local track states nothing bigger than a 15 what 4stroke will fit in with these rules? 26, 30, etc. What is a good temp to run these around? I never dealt with 4 cycle before... :confused:

[Doug Carter]

Rule of thumb is double the displacement of the 2-stroke to get the equal 4-stroke displacement (twice the movement/stroke). A .12 2-stroke figures out to the .26, as a .15 would be a .30 4-stroke. Likewise, the .21 would be close to a .40 in a 4-stroke.

I don't think many of us are worried about running these with the other cars. Based on the availability of the OS car-oriented 4-strokes, there won't be more than a handful of these ever run in newly built dirt cars. I don't see the airplane-based engines working too well for our applications.

:(

[Jeff Harper]

In pro quad racing, four stroke technology has come so far that the rules have been changed recently to allow 300cc 2 stokes to run against 450cc 4 stokes. The gap is closing on the difference between the two (not necessarily for R/C). Anyway, my thinking would be that the airplane motors (besides the gearing problem) would run hot in a car with not near as much movement of air. I would think the car motor would be designed with much more capacity to displace heat.

[hawgmaster]

Hey guys,
heat is a problem with these motors, that is why when they werer available in the Kyosho super ten cars , the on road car , it also had a little belt driven cooling fan that ran off the crank. I have one of these little beauty's on my .40 car and it is the chit, keeps my 4 stroker cool.
Tower hobbies did stock a conversion kit to put a .40 4 stroke in an Inferno buggy , but it is discontinued now. They do however still stock some of the parts and they do have a few of the cooling fans.
There was a production 1/8 scale car that like the super ten came out of the box with a 4 stroke engine. In Japan the 4 strokes are very popular for on road race cars.

I like to run straight pipes on my 4 strokes cause I like the in your face sound of them, but you can put a tuned silencer on them and they are very quite.
I will post some picks of my cars tonight.............Todd

[Doug Carter]

I just got confirmation that Hobbico (OS's US distributor) will definitely be importing the new version of the FS26S-C ver. II (car version) to the US in the next month or so. It will be in very limited numbers, but if they sell well, the opportunity is greater for increased distribution here for 4-stroke car motors. Tower should probably be the main source to easily find them. (http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXJRW8&P=0)

It should be around $220 for those of you interested, so you don't have to jump at the old version on eBay that went from $199 to $235 in the last week after it didn't sell the first time. ;) There are no performance differences between the two, as dyno tested by an outside source, but there is a new carb that will tune better than the old version. Visual appearance differences are the only real changes to the motor that aren't structural.


I guess we'll sit back and wait, then, unless someone finds a stockpie of these in a hobby shop somewhere. I know I'll be collecting parts for a second car in the meantime. :D

[Doug Carter]

wOOt! I finally got my hands on a new OS FS26. I'm stoked. Now the gears are REALLY turning in my head. Whoo hoo!

By the way, for anyone still interested in this, the new spec II versions of these motors are now in the U.S. in very limited quanitites and IN STOCK, sold at Tower Hobbies for $219 (http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXJRW8&P=0). Get one while you still can!

Give the distributors a reason to keep selling them in the U.S.

[Red Baron]

4-Stroker in a car... Very interesting. I know the biggest reason for using my 4-stroke in RC planes is "scale" sound, better fuel efficiency and more torque to swing a larger diameter propellor. However they do require more maintenance but turn out tons of torque. The folks who fly pattern choose these types of engines over 2 strokes just for the wild aerobatics, quick response to throttle input and with a wooden prop, less/lighter spinning mass to get the prop's outer edge(where lift is generated at higher RPM) to speed quicker. Sound familiar to gearing? Things that make you go...hummm.

[racer#57]

Keep us posted on any updates

[EVLJSS]

Hi Doug

could you email me info on how to install and gear the car?

Bob

hobbyforu@aol.com

[Doug Carter]

Well, there is no real pre-fabricated way to do this conversion. It is a tinkerer's project. Motor mounts, clutches, gearing and lots of other things don't really have a good source, because nothing really exists. Creative adapting of other parts, and knowing a machinst will certainly help.

I am talking to a couple of different individuals about getting some small runs of clutch parts and other pieces to allow RC10GT pieces to be run on the 4-stroke.

For anyone interested, there is a new OS FS26S-C II on eBay right now, at a price less than Tower is offering:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=34062&item=5981097755&rd=1

[racer#57]

Hey Doug,
Put me on the list for parts for my GT. I would love to put one together
Thanks Greg

[duratraxslider]

you race gocarts on the dirt in florida we race them dow here in Tucson,Az also on the dirt.

[Barts_GT_Racer]

wow, id love to try and put a 4 stroke on any of my cars, now maybe os should come out with an overhead cam engine to run lol.

Mitch

[az sprint]

Anyone figure out how to get a flywheel and clutch set up on that new o.s. 4 stroke ?
I would like to try a 4 stroke if i could get it in my sprint car.

[EVLJSS]

Ok I guess I just have to get one of these and start the process. I have installed the O.S. 40 in a converted 1/8th csale rally car already but was just looking for suggestions.

I am also Hobbyshop (hobbytown USA) owner and have access to O.S. engines. If they are available from G.P. i can deliver these shipping included for $200.00. LMK

Thanks
Bob

[az sprint]

Found it has a 1/4-20 thread on the crank. It seems most clutchnut/pilot shafts are metric.
What about a .21 threaded pilot ?

[Doug Carter]

Yup, I'm working on trying to get a clutch nut made exactly like the RC10GT, except with a 1/4-20 thread, to mount GT/NTC3 clutch assemblys or other similar metric clutches. I think that is the main stumble block to a simple install. The only other non shelf major part would be motor mounts, but anyone with a drill press and taps could adapt something to their particular car.

No immediate timeframe on the clutch nuts, though. I have a few too many "projects" on my plate.


BTW, that's a good deal on the new version engines. I wonder how many they imported into the US? I heard only a VERY few to gauge interest.

[az sprint]

Wondering about the listing of associated gt clutch nut on Tower Hobbies site.
It stated one was for motors made before 1993.Could the old O.S. motors have a 1/4-20 thread like the new 4 stroke ?

[EVLJSS]

No updates on the clutch mounting ? You guys giving up already?

[Doug Carter]

Nope, not at all... but between building my sprint car and my nitro touring car, my 4-stroke project will be waiting for winter, at least. Once I get over the clutch nut issue, and it shouldn't be a major one, I think everything else may fall into place on the sprinter.


d

[DirtFords1]

Fellas,some of you might want to contact Wolfpack radicals,as he's done some work with the thumper motors.Here's a link to take a peek at!! Maybe this will help.
http://www.wolfpackradicals.com/html/4_stroke.html
I have the new .26 SC II on the way,as I'll be bolting mine in a terminator chassis.
Imagine 8 or 10 of these in a heat race!! :D Hope this helps.

[Doug Carter]

Well, the 4-stroke project took a different turn. I will be dropping it into the GSX sooner than later. I figure if I don't have the time to race anyway, I may as well build something radical and fun, right?

Photos soon of the car with the motor set in for placement. It's a direct fit with a little creativity needed for exhaust placement. Nothing that a straight pipe can't fix. :)


More later...

[Doug Carter]

BTW, I have found out that the Associated clutch nuts are different, depending on the application. The extended clutch nut for threaded engines are 5mm with a .8 thread pitch. This is the one with the shaft that the clutch bearing ride on. The single nut that goes over the threaded SG shaft is a 1/4-28 thread. Ironically, backwards from the way we need it to be.

I'm going to have the opposite clutch nut machined with the shaft on it with 1/4-28 threads to make the Associated NTC3/GT clutchbells direct bolt-up.

[az sprint]

Hey Doug, Check out this clutch nut tower hobbies #LXU750. Its for a .21 in a Kyosho but it has a 1/4" thread. Its less than $5.00
Hope this works. It would be great to find a off the shelf part.
Does anyone have a idea for a flywheel that might fit ?

[sprintracer]

Im interested in building a gas cobra sprint any one heard of a conversion would like to use a four stroke if possible. thanks

[Doug Carter]

AZ: Cool find. It looks similar to the Associated part, without the groove for the clutch shoe/springs. I think I'm going to throw that into my order the next time I go on a Tower binge. I have been searching for something that would be an off the shelf fix, but as of yet, nothing that is still being made.

sprintracer: I don't know of any gas conversions specifically for the Cobra, so it looks like y ou might be on your own with that one. Anything can be done, so don't give up on it. There just isn't anything that you can buy as a kit. You might look to Dynotech Racing, as Chad can pretty much make you anything you want, if you know what you need. As for a 4-stroke package, there is NOTHING out there to drop one of these into any dirt oval car. I'm working on a project right now to see what a potential kit would consist of, but right now, you had better know a machinist. ;)

Also, when you find the FS26S-C, buy it. No one knows how long they will be available, as the American distributor did not import very many of the new version II. I have seen them as low as $199 on eBay.

[DP-Buggyboy]

Hey guys, thought I'd register over here... I like to keep up to date on all things thumper!

I've done a few 4 stroke conversions of varying degrees of difficulty (touring car, 1/10th 4wd buggy, gas truck, Revo), but I've always found I can run the engine much harder if I use a cooling fan. My favorite is the Kyosho Nitro Blizzard cooling fan.

FYI: The Kyosho cooling fan is available. Your local hobby shop should be able to get one once they have an account with Kyosho America. It is the Nitro Blizzard cooling fan, part# 39642. I think that comes with the belt too, but in case it doesn't, the belt is part# 39642-1.

This should be less than $10, since it is the same as the old Baja Beetle cooling fan, which was $8.99

This fan works perfect in conjunction with the OS FS40 Drive Washer, as it has a groove in it that works as a drive pulley. This also places the fan very close to the engine and cools it very well... So good in fact, that there is no need to ever let off the throttle as far as the engine is concerned!


These amazing little engines seem a perfect match for dirt oval, since they can run wide open indefinately with proper cooling. Then of course, there's the axle pin snapping torque!

On the FS26S-C, I've found the fastest and most consistent setup is to use the Kyosho fan, a slide carb from a CV-R, a Perry VP-30 fuel pump, and a 5/16" brake line open exhaust, running Morgan 30% Heli fuel.

These mods bring the engine from a mild .5 HP with 22000 max RPM to what seems like well over 1HP and about 27000 max RPM. For even MORE power... all one has to do is drop in the FS30 piston, sleeve, ring, and piston pin.

Now, I don't have a dyno, but I can say this: My old worn out FS26S-C in my 2WD gas truck gives up nothing to an 1/8th scale buggy with a NovaRossi P5 in a straight line drag-race, as long as I can keep its front wheels close to the ground! I've always wanted to see that power put to work in a late model dirt oval racer...

I used to live and race down in Phoenix, AZ and started racing on the 290 foot dirt oval at R/C Sports-Mania, back when the Tamiya TGX was king. Guys were running those and the Megatech, and the occasional Pirate 10 DTM with OS big block .15 engines, 2.2" buggy wheels and tires, and BIG side-dams! Big-time fun! I know if there was a good dirt oval in Spokane, there'd be an FS26 powered late-model burnin' up the clay!

[Doug Carter]

Welcome to the forums, Damon. There is some pretty good interest here for a decent 4-stroke conversion for the dirt oval cars that are out there. I think it is totally a viable option, and a great addition to the classes for the tinkerers.

My sprint car is coming together slowly, but I am getting closer to a correct motor mount for the kit CW nitro cars. I think my biggest hurdle is still a correct, over-the-counter solution to the clutch, to mate with the RC10GT tranny.

I'm getting closer. :)

[DP-Buggyboy]

On my gas truck, which uses GT spur gears, I ended up using a Monster GT spur and clutch bell. That way, you can use 1/8th scale clutch hardware (clutch nut) and 1/8th scale clutch bells. It allows gearing from 13/52 to 19/46. (using a 19T Savage clutch bell) My truck uses 17/52. You guys use buggy wheels on your sprint cars, so you need taller gearing than a traditional gas truck.. I am guessing 19/46 will do the job, and it's all off the shelf parts. The only mod needed is to drill a couple holes in the spur gear so it will screw to the slipper hub like so:
http://home.comcast.net/%7Edp250f/pics/RC/4-stroke_truck_004.jpg

[az sprint]

Hey DP What is the gas mileage of that 4 stroke in your GT compared to a .12 2 stroke in minutes?

[rm-rf]

Right now the biggest hold back I can see on doing a 4 stroke car for me is none of the tracks around here allow 4 strokes to run in the sprint or edm classes :(

[aceedmonds]

Hay DOUG ,I heard Randy Hubana has a new 4 stroke sprint car the word around here is it has a .46 and a 2 speed trans. I also heard it has 2 cooling fans hooked up to keep the big stroker cool .I will see if I can get some pics and a parts list to put one together.

[Doug Carter]

Right now the biggest hold back I can see on doing a 4 stroke car for me is none of the tracks around here allow 4 strokes to run in the sprint or edm classes :(

No tracks allow them yet because there are none to compete yet. I don't think anyone has tried to get them into any classes yet, so its one of those, "build it and they will come" things. There is really no reason that anyon could give to keep them out of a race class, as long as they were the correct displacement (.12 2-stroke = .26 4-stroke, .21 2-stroke = .40 4-stroke). Other than mileage, there is no huge advantage to them. AMA Supercross has allowed them with the 2-strokes for years, so there should never be a problem when the time comes.


Hay DOUG, I heard Randy Hobena has a new 4 stroke sprint car the word around here is it has a .46 and a 2 speed trans. I also heard it has 2 cooling fans hooked up to keep the big stroker cool .I will see if I can get some pics and a parts list to put one together.

Wow, that's an 1/8th scale size engine! Is it an 1/8th scale car? I know they made a .40 for the cars (different RPM range than planes), but they are really hard to find. Two speeds would make it illegal for just about every oval class I know of. Might be a necessity with the gearing available out there for the 2-stroke cars. I bet it's damn cool, though. :D

[rm-rf]

Well I have one of the FS26SC engines on back order with tower. I haven't decided between a Klein or a Custom works chassis yet. Still debating that. Figure I'll make that decision once the engine gets here.

[DP-Buggyboy]

Fuel economy, NovaRossi CX12 vs. FS26S-C.... the FS has slightly better fuel economy, when tuned and clutched right.

For those interested in BIG BLOCK 4 stroke action... it is possible to convert an FS52 into a high-revving "car" version. You have to be really good with a dremel and have mad drill press/hacksaw/file skills to successfully make the intake manifold required to mount up a .21 slide carb. Just drop in FS40S-C valve springs and spring seats (dremel work and shims required to fit the springs), along with an FS40s-C cam. I suppose you could get more revs with the FS-26S-C cam, but it's really not necessary. I have one in my Revo, and it's unbelievably fast!
http://www.rcccs.com/index.php?showtopic=683&view=findpost&p=11305
:skull:

[smitty]

I think Randys' car has a .26 not the .40, but with a two speed.......trick!

As for being illegal, there is no class for the 4 stroke stuff, so why not a 2 speed?

If we only knew more.......

[Doug Carter]

Good point, Chad. I was recalling Roy's rules prohibiting 2-speeds, but now that I think about it, I think Roy's rules also restrict engines to 2-strokes.

Then again, if the rules don't say it, why not try it, right? :D

[DP-Buggyboy]

I wouldn't invest any time in grafting on a 2 speed... Just gear for what you want your top speed to be. These engines have enough torque to deal with super-high gearing and still have enough power to wheelie from a stand-still.

Also, 2 speeds may have improved lots in the last 5 years, but last time I used on in my Pirate 10 on a dirt oval, it just made it harder to drive. I had to anticipate when it would shift down going into 1 and 3, and when it would shift back up coming out of 2 and 4. VERY difficult to hold a consistent line with all the shifting going on. In the end, I put the single speed back in.

[smitty]

Randy's thoughts.....Dynotech's work.

[Doug Carter]

WOW! :o :eek:

Cubic dollars, man! Holy crap!




Is that an 1/8th scale clutch and 2-speed?

[Doug Carter]

My apologies if I am outting an aution that any of you were waiting to snipe, but there is a new OS FS26S-C engine out on ebay right now, with a few hours left on it, and it is REALLY low. The only real difference between this and the new vII engine is the carb and manifold, which you can usually pick up very cheaply to upgrade.

Find it here (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=5988924327&ssPageName=STRK:MEWA:IT).

I bought mine for about $160, but generally they run about $200 if you can find them new.



Go get it!

[DirtFords1]

Doug,You got e-mail!!;)

[Doug Carter]

Got it, Dan. I'll reply, but right now we're headed to the in-laws for lunch.

Also, I have an extra FS26-S-C brand new in the box for sale in the Classifieds section if anyone is looking for one.


d

[DP-Buggyboy]

I got a part number for the 90 degree intake manifold, and found a place in Japan that will sell them. They are about $25, depending on the current exchange rate.

I ordered 2 of them, one for my gas truck and another for a friend who wants to put an FS26C in his gas truck. As long as there's not too much of a performance hit, I think this manifold will be just what the doctor ordered.:D

Oh.. the part number: VZW039-7 (http://translate.google.com/translate?hl=en&sl=ja&u=http://www.f-sangyo.co.jp/shop/goods/goods.asp%3Fgoods%3D4955439790205&prev=/search%3Fq%3D%2522VZW039-7%2522%26hl%3Den%26hs%3Dzrj%26lr%3D%26c2coff%3D1%2 6client%3Dfirefox-a%26rls%3Dorg.mozilla:en-US%3Cimg%20src=%22classic_images/smilies/redface.gif%22%20border=%220%22%20alt=%22%22%20tit le=%22Embarrassment%22%20smilieid=%223%22%20class= %22inlineimg%22%20/%3Efficial%26sa%3DG)

You can order from here:
http://www.pro-s-futaba.co.jp/tuusinhanbai-os.htm

They prefer PayPal.

[DP-Buggyboy]

Well, I got the intake manifolds in the mail the other day and they are VERY nice! They allow you to mount a standard .12 size 2 needle carb at a 90 degree angle. They even have a 3rd screw hole to allow tilting the whole assembly up about 15 degrees if you want.

When I get back from this weekend's race, I'll have to pick up the new head I ordered from a LHS and try it out in the gas truck.

[DirtFords1]

DP,When you get it all together,post some pics,i know I'd be curious to check them out.
I'm workin on on a little something myself,I'll keep everybody posted.


Doug,How was lunch at the in-laws?? ;)

[DP-Buggyboy]

The manifold is a simple bolt-on part. No mods necessary, just a thin layer of silicon on the gasket surfaces to seal it up so it doesn't spew fuel all over your car. I probably won't work on this until my fall racing season is done.. in late October. If I do it earlier, I'll post some pics here.

[DirtFords1]

DP,well if and when you get it together,post those pics!! Thanks.

Doug, You got e-mail !!

[DP-Buggyboy]

Well, here it is, the beautiful intake manifold:
http://home.comcast.net/~dp250f/pics/RC/90_manifold_001.jpg http://home.comcast.net/~dp250f/pics/RC/90_manifold_005.jpg

I've decided to run both my 4 strokes at our r/c club's next big race on October 22-23. This is for the FS26-C in my gas truck.:D

[DirtFords1]

DP,That looks like what the doctor ordered for the 4-stroke.If you don't mind,what did it cost you with the shipping??Let us know how it works on the motor.

[DP-Buggyboy]

$25 shipped.

[DirtFords1]

Here's a few pics of my build,going on a 2.25 terminator chassis.

[DP-Buggyboy]

Those engine mounts are NICE! Are they available for purchase, or are they custom?

[John Binz]

That is sweet can't wait to see pictures of it all together. :p

[DirtFords1]

Fellas,Stay tuned,I'll get it finished as soon as I can.Still have a few things to do yet.

The motor mounts might be hard to come by now a days, they were made for the older Ofna z-10.I would give Wolfpack radicals a call,and speak to Wolfgang.His link is in this thread.

Fellas,Thanks for the flowers!!;)

[axis]

You can also contact Litespeed Engineering in San Antonio,Texas. He builds drag cars but has some very nice adjustable motor mounts he uses on his drag cars. I have a set and they are very nice.
http://litespeedengineering.com/

[DP-Buggyboy]

The motor mounts might be hard to come by now a days, they were made for the older Ofna z-10.
Hmm.. That's ironic, the first car I ever put a 4 stroke in was a Z-10, but it was the cheap sport version with the cheap adjustable nut type universal engine mount. Thanks for the info.

[DP-Buggyboy]

DP,well if and when you get it together,post those pics!! Thanks.

Doug, You got e-mail !!

Here's some pictures of the gas truck with the new manifold installed:

[DP-Buggyboy]

Well, bad news: The manifold adds too much intake volume, not to mention it provides a place for fuel to pool. That means bad throttle response, bad idle-down, and no amount of tuning could compensate for it. I tried it with and without the pump, but couldn't get it to run good enough to even want to run it on the track.

I give the manifold a 2 thumbs down rating.

[jwelch5792]

I need a flywheel collet for a o.s. fs-26s-ver. II that would be used with a ntc3 flywheel.
Any help.
Thanks
Jesse:D

[DirtFords1]

fellas,here's a couple pics of the 4-stroke car,not quite complete,but you get the idea.Gonna use an Oldies body,prob the one in my avatar.Hope you guys dig it!


Try this link: http://community.webshots.com/user/danrcfords (http://community.webshots.com/user/danrcfords)

[DigDoug456]

The picture dosen't show for me what am I doing wrong.

[DirtFords1]

I just went to the album,no problem,takes you rite to the page.......????????

[bulitbill]

same problem here, no picture

[DirtFords1]

I went back and installed a new link,try this,shouldn't be a problem. ;)

http://community.webshots.com/user/danrcfords (http://community.webshots.com/user/danrcfords)

[Tall Paul]

Still not working Dan.

[DirtFords1]

It's all working fine on my end,don't know whats wrong.

[/url]


[url="http://image62.webshots.com/62/0/20/33/2456020330041037189kSARvA_ph.jpg"] (http://image50.webshots.com/150/9/10/95/2529910950041037189PlNIzT_ph.jpg)

[Tall Paul]

Pics are working for me now.

Looks good Dan