CEO

Has anyone tested a 4 stroker in a boat before? If so what were the results? I think it would be cool to have the 4 stroke sound in my boat. I understand that a 4 stroke wont have the rpm that a 2 stroke has but I figured I could add a little nos or a gearbox for coming out the the corners. I've also scored a free RB supercharger that was on my buddys mt2. Anyone think I'll have better results than he did if I put this on a 4 stroke nitro motor? Please no killjoys or hijacking. Please don't flame/rage or post any rude comments I'll have your post deleted. Thank you for understanding. Sorry to the people that dont do such things.

CEO

siberianhusky

A supercharger should work in theory on a 4 stroke, The problem I see is how do you control the mixture? Same with nitrous, You need to get more fuel into the mix, Not sure how a carb would work under the pressure of a forced induction system instead of vacuum. Might really mess up the bernouli effect and you carb might pump air into the tank instead of fuel into the engine!
Super and turbo chargers never made it into mainstream use until fuel injection came along, To have it running right at the top end I'm willing to bet it would be so rich everywhere else it wouldn't work.
Now if you could figure out fuel injection on one of these you'd be set.
The oxygen in Nitrous oxide is what gives the power increase, more O2 means you need more fuel, with the almost fixed metering system in an rc engine you will run into problems of rich in some areas and deathly lean in other areas.
Now you could set it all up to work fine at full throttle for straight away racing or something, Just set it up so you have proper fuel delivery at full tilt and live with the messed up running conditions at other rpms.
Great idea and works in theory but the problem as I see it is our carbs cannot take advantage of forced induction. Rc carbs are about as basic a carb as you can make run an engine, basically a tube with a hole in the side to meter fuel in and a valve to control air flow.
The other issue is compression ratio, forced induction engines run a lower compression ratio than a normally aspirated engine, the have to to avoid detonation due to you artificially increasing compression because you are forcing air into the engine.
That is the reason "off the shelf" turbo kits for cars have such low boost values, zipperheads with honda civics are not going to do the headwork on the engine, they just want it to look cool under the hood.
Lots of cool looking useless stuff out there that is relying on the bling factor to get somebody to part with their money! Those superchargers were sold to work with a 2 stroke! Anybody else see the problem with a supercharger on a 2 stroke.
Also I don't find one of these little 4 strokes really sounds much like a "4 stroke" To me they sound like a 2 stroke that needs a good carb tuning! Add the extra weight and loss of power and added cost, just to go slower than everybody else!?!
Look at motocross bikes, when they were running 2 strokes the bikes were 125 and 250 cc, now that 4 strokes are in the classes have changed to 250 and 450cc. They had to double displacement to keep 4 strokes running with 2 strokes.
I remember when Quadra engines made it onto the scene, people raving that they sound like a real plane engine! well maybe an ultralight but I've never heard a full sized plane that sounds like a chainsaw!
These little engines don't have enough torque to "gear up" to get more prop speed, at least not enough to make a difference. You wouldn't be able to run a 2:1 overdrive say and spin the same prop as a 2 stroke.
I wonder what would happen to the valve train if you did try nitrous or a supercharger? Wonder if the cam would have a grind that would be able to take advantage of forced induction? Too much overlap and that extra charge would go straight out the exhaust doing nothing for you.
Lots of thing go into designing an engine to work in a specific manor, usually trying to do something major to an engine will bring less performance or reliability unless you have the money/knowledge to adresse every part of the engine as it all has to work as a complete system from the carb to the exhaust pipe! 30 years of kart and bike racing have taught me that lesson too well!

Hydro Junkie

The only turbocharged engine with a carb I personally have ever seen was used in the 1979-81 Turbo Trans Am. It used a standard Rochester 4bbl dumping into an intake plennum that ran across the top of the engine to the turbo. The turbo then force fed the air/fuel mix into the intake manifold at between 4 and 7 PSI depending on the engine load and boost required. This was used to increase the HP from a little 4.9 liter V8 when GM was forced to drop the 350 and 400(+) engines from their production line to meet the then new economy laws. The set up did have a drawback however. I ran into a problem in Michigan in 1986 with ethanol added gas. It appeared that the ethanol was burned out of the mix going through the turbo causing major problems in getting the engine to run properly. As for how it performed, my Trans Am was able to outrun other sport coupes and pony cars both from a standing AND a rolling start.

joseywales

The Buick Gand national had twin turbochargers. As for your Trans Am. the Gand national would suck your carup and blow them out in pieces HJ. As putting NOS on a small engine? Waste of time and money.

siberianhusky

Coolest one I've ever seen was at a car show, a rat rod pickup with a 292 inline 6, it went turbo, intercooler then a neat plenum that fed 3 side draft carbs! Never got to see it run though. Just sitting there.

lipdaddy

The Buick Gand national had twin turbochargers. As for your Trans Am. the Gand national would suck your carup and blow them out in pieces HJ. As putting NOS on a small engine? Waste of time and money.
[/quote]


The Buick Grand National was a single turbo car from the factory.

Ron Olson

My Feedback: (1)

The GNX was the twin-turbo version.

tnltyme

Here's a twin turbo GNX. Note where the exhaust is. This one is 1000hp. Pretty impressive. Not sure if they came with twins from the factory. All I've seen listed is a Garrett turbo. Nothing about twins. 276hp. Only produced in '87. I bet that's the year they beat the Vette. Although, factory 80's Vettes were nothing to write home about. Here's the 1000hp vid.....

http://www.youtube.com/watch?v=fs7hGJ1vkhc

toyotatruckin

Back on track here, CEO if you do a search here on the nitro boat section I remember seeing a couple other threads related to the 4stroke plane engines being put into boats,think there was even a video of one guys 4stroke boat running but it has been a year or two back so you may have to dig deep
-good luck to you!

chief3452

There was a really nice deepvee that had a Saito 4-stroke with a gearbox in RCBM probably 15 years ago, I will see if I can find the article and post it. As for the RB supercharger, I have never heard of anyone who had any good results with one.

lipdaddy

Not to thread jack, but I'm a big fan of the GN and have never seen or heard of this version. Could you post a link to a factory twin turbo GNX?

Ron Olson

My Feedback: (1)

Oops, I blew that one as I could have sworn that the GNX had twin turbo's!
I've ridden in 2 GN's, one that my brother-in-law had and one that a buddy from worked owned. Damned fast cars for a little 3.8 V-6.

Mike, that boat was the Four Play that was on the inside back page of that issue of RCMB, THAT I remembered. He had the motor turned around and hooked to a gearbox.

I wouldn't try NO2 in a boat. I had a bud that tried that with a 7.5 OB tunnel. The engine is scattered in various parts of a lake........
NOS is a brand name but ever since that stupid The Fast and the Furious movie came out some people refer to any nitrous oxide system as NOS.

Justaddwata

My Feedback: (3)

you will, will you??

I have seen a couple of scale boats running 4 strokes. Decent enough speeds but scale still. I am not sure what speed your going after but 4 stroke will limit your effort.

I would not waste too much time/effort with the small after market super chargers or NOS. There are a few 4 stroke super charged plane motors but I could not tell you much about them (remember seeing some ads about 20 years ago) since planes and I dont work well together. If you want the power of a super charger then switch to 2 stroke and run a pipe.

lipdaddy

no problem, i thought there was a bad ***** GN i never heard of.

Back to the thread, I couldn't imagine running NO2 in a little nitro engine. I've run it in a 2.0L for the last 7 years w/o any problems but thats alot larger scale.

Ron Olson

My Feedback: (1)

After my bud gave a new meaning to K&B's Ka-Boom nickname I figured that "laughing gas" wasn't a way to go.
I think (yeah, I'm doing that again!) that it was O.S. that has a supercharged .91 but the blower was made for help in pumping more air in at higher altitudes than a HP gain.
Most 4-strokes are hard to water-cool. The Saito did have a water-cooling jacket from the factory.

amax

Well I guess I'll give My Take on this,,[&:]

The R\C 4 stroke engines I have seen are Air Plane Engines and are Low Compression, Low Performance engines made to run at half throttle with No Glitches or as little as possible, So the engine does Die in the air and Drop the plane from the sky. Where you will have issues getting real performance from one is valve size, Cam Duration and Lift, and the bottom end Isn't built to hold A Lot more power. Anything that works on Larger 4 stroke engines Will Work on these little engines but may only do it for a Short Time.

Contrary to Popular Belief a Forced Induction System WILL Work on a R\C Nitro Engine if set up properly. The issue I see with the RBinovations system is the SC is On Top of the carb and not Between the Carb and the intake so it Pulls the Air through the carb and getting the proper Air\Fuel Mixture. Then you also run in to some of the same issues as the plane engine with Over Powering the bottom end.
The Key to Forced Induction in a 2 stroke engine is Balancing the Boost and Combustion Chamber Pressure. When you Force air\fuel into the block You Pressurize the block which in turn Fights against the Piston on the Down Stroke, and Raising the CR higher in the Combustion Chamber. You must raise the Ex Port height and Increase head volume to compensate for the added volume of Air\Fuel entering the chamber and Increasing the Compression Ratio(CR).

Iflyglow

My Feedback: (79)

You must not have checked to hard, since the same year "Turbo" Mustang was also carburated and used the same Garret Turbo charger. There are quite few N/A four cylinders on the market now that would also eat it up and spit it out for breakfest.

In 1980 Pontiac dropped its 400 V8 and installed a new Turbo-charged 301 (4.9 liter) V8 as its top Engine choice. The notorious "Turbo 4.9 was rated at a pathetic 210 bhp, but the real issue came from its actual performance. There was no Turbo boost indicator as Turbo lag was a huge problem and the Engine often made loud pinging sounds under heavy loads just before it self-destructed. Nevertheless, a Pontiac Trans Am paced the Indianapolis 500 race that year. Sales dropped considerably.

amax

Yea IMO the 301 was one of Pontiacs Biggest Mistakes, I Never seen any of them that could hold a candel to ANY of my 78 T\A's running a 400ci Pontiac Engine(Not he Olds 403) in a 1\4mile or Top End.

Iflyglow

My Feedback: (79)

As far as four stroke Glow engines go, welcome to the line of YS engines. They are not your ordinary model four strokes, and will provide the excitement you are looking for, but you will have to run a gerabox. They are Crankcse Supercharged providing about 7+ pis of boost, and are injected, and will out perfrom two strokes of the same CI any day of the week. They are not new, and have dominated the area of Pattern flying and racing for about 20 years now. Piped two strokes have tried to compete against them, but they never really could. OS went as far as to design a 1.40RX two stroke with EFI and all, and it still could not compete. In the world of pattern they compete CC for CC.
The smallest being the FZ70 will turn up to 15,000, but the 1.10, 1.40, and 1.70 are designed to be run @ about 9,000. They provide some serious grunt in model planes, and are like comparing a Ferrari to a Kia in comparison to the other 4 strokes on the market. No need for NOS, since they are designed for 20% Nitro, and in competition are run on up to 60% and more Nitro.

http://www.centralhobbies.com/Engines/ys/ysengines.htm

http://www.youtube.com/watch?v=cK2yV...eature=related

http://www.youtube.com/watch?v=SHIM3...eature=related

chief3452

Here is the scan of the article in RCBM. For what it's worth, the boat looks pretty sporty in the photo.

I scanned it sideways to increase the clarity of the scan.

amax

Well I geuss theres Always an exception to The Rules,, LOL. that's some nice Flyin and camera work to stay on that thing that well going that fast[:-]
It would be interesting to see that engine set up in a boat and compare it to a comprable size High End Marine 2 stroke, your not gonna find one that matches it CC for CC as it doesn't match any of the Popular Race class sizes where you will find the High end marine engines. 15,000 RPM is a far cry from the 27,500 delivered by the .67 CMB, if it can turn a lot more prop at the lower RPM and make up the diff it would be somthing to look at for a Pond Hopper but it wouldn't be legal in any of the exsisting racing classes as they don't allow "Super Chargers".

coriolan

Years ago Saito had a single cylinder 4-strokes (.30 I think) and OS had a .60 too. OS also had 4-strokes for cars with pull start, but none of these where racing type more like for scale use.

Hydro Junkie

Geez, you guys are missing the point. I was trying to give an example of a carbed engine that worked with a supercharger by putting the turbo in between the carb and the intake manifold. Since you guys want to bash the turbo 301, here's my take on your posts.
Amax, the 301 was never intended to match the 400/403 equipped TA's. It was intended to give a respectable torque and HP rating with a higher MPG than the big blocks could deliver. I drove mine from Seattle to 29 Palms CA and on to Meridian MS with an average of 22 MPG. I also found that by using the turbo lag to my advantage, I could outrun the big block equipped cars, including Vettes, from a standing start by letting them smoke the tires while my 255/60-15s were grabbing the pavement and launching me down the street due to it's slightly lower torque and my using my head over most others just mashing the gas pedal through the floor.
Iflyglow, I never said there were no others, just that the 301 was the only one I personally saw. Then again, I've never been much on Fords. Not sure where you got that quote on pinging before self destructing. I put around 100k on my 80 TA, starting in 1983, with the only problems I had being a blown head gasket under the left head in 1987 and a burned exhaust valve seat in the right in 1986, 40K of hard miles earlier.
Joseywales, the GN and GNX were fuel injected cars, not carborated as the 3.8 turbo was SFI equipped in 1984 and the GN series started in 1985 as an optional package on the Buick Regal that ran into the 1988 model year so it's not applicable to this discussion. The Generation II version of the 3.8 liter sitting in my driveway, with it's Eaton M-90 supercharger and 150K miles would probably give the GN a run for it's money, if not beat it outright.

Now, lets leave the cars behind and get back to the subject at hand

Iflyglow

My Feedback: (79)

I am talking about planes where they compete CC for CC. They make up for RPM difference by running much more pitch and dia. You are correct, that for your purpose they would not work. But in the relm of model planes, they are the sh** for all out performance.

amax

Yea I know,, were Talking Apples and Your talking Oranges,, but it would be Interesting to see one installed in a boat, it should spin a prety meaty prop.