The difference between car and marine engines

[anthony_marquart]

What are all the differences between car and boat engines? Seems like you should be able to take a .21 car engine, change the timing with different machining on the sleeve, and use a simple water cooled head, and whala.. Maybe different bearings for continual high speed use. I could be totally wrong here but one would think that an engine manufacturer that makes .21's currently would be able to make a sleeve and cooling head, then have a .21 marine engine to push into the market. Of course this engine would probably not be like a new MAC but but hey,.. most of us can't justify one anyway.

http://www3.towerhobbies.com/cgi-bin/wti00...LXFAC3&P=R.. Take this engine, with timing for a marine engine and a water cooled head. It would probably be fine for most club races. It seems to me that there is actually money to be made here.

I don't know how the sleeves are actually manufactured but if the ports are CNC'ed, all it would cost is the additional programing to cut the ports. they could even use a die-cast cooling head, just machine the sealing face and thread the water ports.

http://www3.towerhobbies.com/cgi-bin/wti00...XBN19&P=R,..

http://www3.towerhobbies.com/cgi-bin/wti00...=LXSLH3&P=R

And .12's.. http://www.nitrohouse.com/images/engine_pi...picco/51124.jpg I think this would be a great marine engine timed correctly.

Maybe I'm way off,.. but it seems like there could be lots more.21 size engines out there without a tremendous amount of work on the manufactures part..

maybe I'm totally wrong.. I must be because no one is doing it..

 

[tnrcboatracer]

Links don't work for me.

But to answer your question, that is what myself, David Hall, and Rod G. are doing. Several of the .12 records were set with used car motor purchased off eBay for $50. We just shim the sleeves a little to get the timing where we want it. In the case of the .12 (and .21 if you want) water cooling is not necessary. We just cut down the air cooled head to get the temp up. There is also a little work required to get the correct cc chamber for the nitro% we are running.

I still have my MAC 21's, and Im not likely to give them up, but it is fun to work with the little car motors as well.

 

[Jerry Wyss]

From what I see it takes someone at the manufacture's level with a design or intrest in boat engines.

Look at Picco and they're story, K&B with theirs,, haven't seen many CMB car & buggy engines.

O.S.,, not hard to see where they're main intrests are,, took someone at Rossi, who was that?

We're a small segment of the RC world,, I would imagine thats where the lack of intrest is, other

than the knowlege of "what" makes a good boat engine.

 

[anthony_marquart]

I have a question about shimming the sleeve on these motors. I know you have to shim the sleeve up about 0.020-0.030 to get the timing up. Then put the head button in a lathe and take that same amount off to keep the compression right. This moves the piston down further from the taper in the sleeve. Is this enough to make a difference? Rod mentions deforming the piston a little to bring back the compression in the motor. How is this done? I've read of people using tubing cutter and running it around the top of the piston to move some material a little bit. I'm thinking that the difference may not make any real effect if the motor is new with a real tight fit. But, if I were to be doing this in a used motor that distance from the taper might have an impact on the compression.

Thoughts or experience with this?

Links don't work for me.
But to answer your question, that is what myself, David Hall, and Rod G. are doing. Several of the .12 records were set with used car motor purchased off eBay for $50. We just shim the sleeves a little to get the timing where we want it. In the case of the .12 (and .21 if you want) water cooling is not necessary. We just cut down the air cooled head to get the temp up. There is also a little work required to get the correct cc chamber for the nitro% we are running.

I still have my MAC 21's, and Im not likely to give them up, but it is fun to work with the little car motors as well.

 

[Swissrigger]

Links don't work for me.
But to answer your question, that is what myself, David Hall, and Rod G. are doing. Several of the .12 records were set with used car motor purchased off eBay for $50. We just shim the sleeves a little to get the timing where we want it. In the case of the .12 (and .21 if you want) water cooling is not necessary. We just cut down the air cooled head to get the temp up. There is also a little work required to get the correct cc chamber for the nitro% we are running.

I still have my MAC 21's, and Im not likely to give them up, but it is fun to work with the little car motors as well.

Jon,

Converting car engines to marine is very common in Europe. Car engines are much easily available compared to marine engines (I refer to Novarossi). Just looking on Novarossi homepage you will find so many different types of car engines with different sleeves, pistons (flat, hemispheric, different materials) so you can choose an engine suiting your needs. Basically the offroad engines have a conservative timing especially on exhaust and the size of exhaust and transfer ports is smaller compared to onroad engines. With a car engine you need to exchange the carb, put on watercooling (from some older motor?) and modify the flywheel to fit on the short crankshaft. Timings of Novarossi marine and onroad engines are the same. Look on the part list at their homepage. Most of the parts are interchangeable.

If you like to look on a list of timing of car engines go to this link (in German): http://www.nitromonster.de/html/steuerzeiten.html

You will find a nice detailed overview of marine engines on the site of Xavier Cardinale from France (French/English): http://www.xae-team.org/first.html

Regards,

Petr

 

[NITROSNIFER]

All my .21 engines are RB (nova based) or Rossi car engines. I have had great luck and other than making a cooling head and modifying the flywheel they work just like their marine counterpart.

 

[mtruex]

Links don't work for me.
But to answer your question, that is what myself, David Hall, and Rod G. are doing. Several of the .12 records were set with used car motor purchased off eBay for $50. We just shim the sleeves a little to get the timing where we want it. In the case of the .12 (and .21 if you want) water cooling is not necessary. We just cut down the air cooled head to get the temp up. There is also a little work required to get the correct cc chamber for the nitro% we are running.

I still have my MAC 21's, and Im not likely to give them up, but it is fun to work with the little car motors as well.

would you care to share a little more info? im setting up a .12 mono and i have an older model but new in box novarossi..its an rs12 5 port, any help on changing the timing and combustion chamber is what im after...thanks MT

 

[anthony_marquart]

To change the timing you raise the sleeve by either making or buying shims, or with music wire from the LHS. Raise it about 0.020. Whatever you raise it you now have to remove from the mating surface of the head button. Now the head volume I couldn't begin to tell you how to measure.

Now exactly how much more duration you get with that 0.20 will depend on your engine but that has worked for me.

Links don't work for me.
But to answer your question, that is what myself, David Hall, and Rod G. are doing. Several of the .12 records were set with used car motor purchased off eBay for $50. We just shim the sleeves a little to get the timing where we want it. In the case of the .12 (and .21 if you want) water cooling is not necessary. We just cut down the air cooled head to get the temp up. There is also a little work required to get the correct cc chamber for the nitro% we are running.

I still have my MAC 21's, and Im not likely to give them up, but it is fun to work with the little car motors as well.

would you care to share a little more info? im setting up a .12 mono and i have an older model but new in box novarossi..its an rs12 5 port, any help on changing the timing and combustion chamber is what im after...thanks MT

 

[mtruex]

To change the timing you raise the sleeve by either making or buying shims, or with music wire from the LHS. Raise it about 0.020. Whatever you raise it you now have to remove from the mating surface of the head button. Now the head volume I couldn't begin to tell you how to measure.
Now exactly how much more duration you get with that 0.20 will depend on your engine but that has worked for me.

Links don't work for me.
But to answer your question, that is what myself, David Hall, and Rod G. are doing. Several of the .12 records were set with used car motor purchased off eBay for $50. We just shim the sleeves a little to get the timing where we want it. In the case of the .12 (and .21 if you want) water cooling is not necessary. We just cut down the air cooled head to get the temp up. There is also a little work required to get the correct cc chamber for the nitro% we are running.

I still have my MAC 21's, and Im not likely to give them up, but it is fun to work with the little car motors as well.

would you care to share a little more info? im setting up a .12 mono and i have an older model but new in box novarossi..its an rs12 5 port, any help on changing the timing and combustion chamber is what im after...thanks MT

sorry i didnt explain myself very well, i know how to raise the sleeve i was looking for actual numbers that have worked good with that engine before..sry i was thinking of starting with .020 and i usually run 50% nitro, what should i look for in head clearance.

 

[tnrcboatracer]

I'm currently working with 122* intake and 175* exh and a super short pipe. In my case the engine still a good fit after shimming the sleeve 0.015". On my RB, 0.025" would give me ~ 126* intake and 179* exh.

Another option instead of shimming the case is machining the piston crown. While you're at it, you can put a 2* taper on the crown and add a slight bowl. Put a matching taper on the squish band, and you'll have the same configuration as the 35 plus.

 

[Jerry Wyss]

Kinda make it sound like the NR's are the only buggy engines that make good boat engines.

If someone screws-up cutting a NR piston crown they're out another $200 for a new P&S.

Some of the "dirt cheap" car&buggy engines make serious racing engines since they have

to be modded in a similar manner as the expensive models. Plus they're bearing replacements

won't make you feel like your paying the power bill all over again.

Its not a matter of throwing in .020 to .025" sleeve shim in and everything will be alright,, in

some 21 engines .020 sleeve shim will put transfers up in the 137* area, bit too high. What

about crank rotor timing? I have a NR21 PLUS-5-T that had 180* total open crank timing,,

the RB728 was the same. The worst I've seen so far have been NR products and gawd

whatta price tag!

There "are" cheaper alternatives out there, it just takes some research to dig some of those

little gems out.

JW

 

[anthony_marquart]

Ok,.. Help us please!!!

In your experience,,Which .12 engines will do well with the sleeves raised to increase timing duration?

I know the OS TZ12 does well with .02. I've done it. but that's not a cheap engine either..

Anyone have timing numbers on the Picco RedDot 12 engine?

Kinda make it sound like the NR's are the only buggy engines that make good boat engines.If someone screws-up cutting a NR piston crown they're out another $200 for a new P&S.

Some of the "dirt cheap" car&buggy engines make serious racing engines since they have

to be modded in a similar manner as the expensive models. Plus they're bearing replacements

won't make you feel like your paying the power bill all over again.

Its not a matter of throwing in .020 to .025" sleeve shim in and everything will be alright,, in

some 21 engines .020 sleeve shim will put transfers up in the 137* area, bit too high. What

about crank rotor timing? I have a NR21 PLUS-5-T that had 180* total open crank timing,,

the RB728 was the same. The worst I've seen so far have been NR products and gawd

whatta price tag!

There "are" cheaper alternatives out there, it just takes some research to dig some of those

little gems out.

JW

 

[tnrcboatracer]

I should have clarified also; you can't just add a shim, you need to map the timing of all the ports in order to know what to add. I use the EAP program to map my port timing, it is the simplest way I have found. Marty has it on sale just in time for Christmas. I highly recommend the EAP if you are at all interested in engine work.

As for machining a piston, yes, you have to be careful. And know what you're doing or trying to do. But that is true of any engine mod. More engine parts have been scrapped by a dremel and carbide burr, than blown up by running. We measure the setup no fewer than 3 times before starting to cut. Runout, perpendicularity, etc, and we also make some specialized holding fixtures to allow up to dial in the parts within 0.0005 before we start maching. There are others on here who setup to within 0.0001, but our equipment isn't that good, the spindle bearings on the lathe are only good to 0.0005". But 0.0005" is within 12.5 microns. When your setup takes a couple of hours, it becomes a labor of love. Most folks aren't willing to pay for this level of craftsmanship. It is something you do for yourself. It really is far easier to do this type of work the first time, when the parts are made by the OEM. The fixturing takes care of itself, as the part itself is the master datuum.

We are using the Picco .12, but I'm not sure of the model; it is a ~$50 engine NIB on eBay. It has a simple 3 port sleeve. Again, it is ~$50 NIB.

 

[Jerry Wyss]

Ok,.. Help us please!!!

In your experience,,Which .12 engines will do well with the sleeves raised to increase timing duration?

I know the OS TZ12 does well with .02. I've done it. but that's not a cheap engine either..

Anyone have timing numbers on the Picco RedDot 12 engine?

Anthony, You have me at a disadvantage with the 12 engines,, all my work has been with the .21 to .30

size car/buggy engines. I had a machinist cut me 760 sleeve shims on a "wire machine" for the 21 engines,

for the larger motors I cut the inside opening on some 21 size headshims.

This is a research game (unless you have other info), looking thu many exploded views and engine specs

til ya go blind. I myself would call Rod Geraghty before I tackled any of the 12's to get an area in timings

where the 12's would run best. Rod has allot of data recorded for many engines, he would be your best

source for such info

I operated on the "buy and see" program and have a few candidates still in the box up on my cabinet

that may be something someday. I know Tim Duggan took a mere Thunder Tiger 12 I/B engine and

made a screaming meany out of it, some of my best running engines are the same manufacture.

JW

 

[Jerry Wyss]

We are using the Picco .12, but I'm not sure of the model; it is a ~$50 engine NIB on eBay. It has a simple 3 port sleeve. Again, it is ~$50 NIB.

I'm in agreement with the simple port arrangement,, try to stay away from the exotic multi-port car engines,

specially with the 12's (I would think)

The simpler less exotic engines ran better for me,, or just as good, and the parts were much cheaper.

JW

 

[Marty Davis]

To change the timing you raise the sleeve by either making or buying shims, or with music wire from the LHS. Raise it about 0.020. Whatever you raise it you now have to remove from the mating surface of the head button. Now the head volume I couldn't begin to tell you how to measure.
Now exactly how much more duration you get with that 0.20 will depend on your engine but that has worked for me.

Links don't work for me.
But to answer your question, that is what myself, David Hall, and Rod G. are doing. Several of the .12 records were set with used car motor purchased off eBay for $50. We just shim the sleeves a little to get the timing where we want it. In the case of the .12 (and .21 if you want) water cooling is not necessary. We just cut down the air cooled head to get the temp up. There is also a little work required to get the correct cc chamber for the nitro% we are running.

I still have my MAC 21's, and Im not likely to give them up, but it is fun to work with the little car motors as well.

would you care to share a little more info? im setting up a .12 mono and i have an older model but new in box novarossi..its an rs12 5 port, any help on changing the timing and combustion chamber is what im after...thanks MT

sorry i didnt explain myself very well, i know how to raise the sleeve i was looking for actual numbers that have worked good with that engine before..sry i was thinking of starting with .020 and i usually run 50% nitro, what should i look for in head clearance.

Martin:

For a .12 you should look to get to about .006" head clearance to have the correct squish velocity.

Marty Davis