90% Nitro

[Joe Warren]

Has anyone ran 90 % Nitro fuel with 10% oil or less... I have been to 70 % but not above... Can the methanol be deleted? or must it remain as a refrigerant?

 

[Rokieboater]

Pretty sure it can be done but you will need an additive to at least get it started. Maybe lighter fluid in the carb before you bump it with the starter.

Robert

 

[dr gary turner]

Has anyone ran 90 % Nitro fuel with 10% oil or less... I have been to 70 % but not above... Can the methanol be deleted? or must it remain as a refrigerant?

Joe, Rossi used to send with their motors a formula for speed racing. The best I can remember it was about 90% nitro some propylene oxide as the igniter and caster oil. I may still have one of the inserts around. This came with their 65 motors. Gary

 

[Terry Keeley]

Playin' with some 85% in the SAW boat, nitro's great as long as you can burn it!

 

[Al Hobbs]

One evening at the 1998 World Championships in France, Andy Brown was talking about running 90% nitro fuel. We were at the Ukrainian camp, drinking their wine and vodka.

As I remember it, Andy said that it took a headbutton with 4 glow plugs to burn all of the fuel.

This is the best I can remember from that evening. The Ukrainian vodka was very potent.

Al Hobbs

 

[David vanmaris]

The best allways have the storiesssss,

 

[Buckshot]

One evening at the 1998 World Championships in France, Andy Brown was talking about running 90% nitro fuel. We were at the Ukrainian camp, drinking their wine and vodka.

As I remember it, Andy said that it took a headbutton with 4 glow plugs to burn all of the fuel.

This is the best I can remember from that evening. The Ukrainian vodka was very potent.

Al Hobbs

Joey,

You'll need something to get it started, the hard part is making use of it all.

Al,

I've seen one of Andy's "4 plug" motors, might have been the only one.



B

 

[Norm Doerr]

80% Nitro

10% Prope

10% Oil

Probobly could bump the nitro with the higher quality oils available today.. (raise nitro reduce oil)

 

[Jim Allen]

Propylene oxide will NOT work properly with 80% nitro, even when used in amounts as large as 15% with 5% oil. However, ethylene oxide works beautifully in amounts as small as 12% with 8% oil. Chemist have explained to me that the oxygen bond in proplyene oxide is much stronger than the bond in ethylene oxide, therefore preventing the easy release of the necessary oxygen to start the high nitro to burn. Henry Nelson & I found that 80% nitro, 12% ethylene, 8% oil will work extremely well in engines from .21 to 1.00 cuin size. It is very easy to needle & can be used in air temperatures down to 65 deg F without oil seperation. In fact, Henry says, "it needles like 30% nitro when used in smaller displacement motors." I found the same thing to be true in my .90 size motors. Of course, larger displacement motors will need a very good "caged" roller assembly to successfully run the lower oil amounts at 30,000+ RPM.

Jim Allen

 

[Joe Warren]

Jim to you consider us to be on edge with 65 percent? It has became a norm for me?? Many run 65 percent in there boats. I have never been under 60 myself.... 70 percent even seems to be safe? If you can afford the high wear on parts ticket that follows. Many say there is no performance difference from 50-65 But If you have your boat set up correctly & Can prop up there is a Huge Advantage in HIGH Nitro Fuels.

 

[Jim Allen]

Jim to you consider us to be on edge with 65 percent? It has became a norm for me?? Many run 65 percent in there boats. I have never been under 60 myself.... 70 percent even seems to be safe? If you can afford the high wear on parts ticket that follows. Many say there is no performance difference from 50-65 But If you have your boat set up correctly & Can prop up there is a Huge Advantage in HIGH Nitro Fuels.

I can't say that one fuel or another is on the edge. I have a fuel formula book that dates back to 1988 with various fuels that were tested on the dyno & at the lake. 65 nitro, 18.5 men, 1.5 prop, 15 oil ran 84 MPH in my .90 engine. 75 nitro, 10 prop, 15 oil ran 88 MPH. 80 nitro, 12 ethyl, 8 oil ran 92 MPH. The increase in nitro didn't make the engine turn faster, but it did increase the torque & therefore the HP.

If the fuel functions correctly or does not function correctly depends on many factors which may be beyond the control of most boaters. The design of pipes, heads, transfers, inductions & exhausts, to name a few must be within resonable correctness for exotic fuels to work in any engine.

Ask yourself, why some present day large displacement engines are burning holes in piston crowns? Is this a fuel problem or is there something very basic that is wrong in the engine's design?

Jim Allen

 

[Gerald Carijuton]

If the fuel functions correctly or does not function correctly depends on many factors which may be beyond the control of most boaters. The design of pipes, heads, transfers, inductions & exhausts, to name a few must be within resonable correctness for exotic fuels to work in any engine.

Ask yourself, why some present day large displacement engines are burning holes in piston crowns? Is this a fuel problem or is there something very basic that is wrong in the engine's design?

Jim Allen

Could it be a piston and head button chamber problem , Maybe a thicker piston to handle the heat of high nitro and a better head button chamber that will burn the high nitro fuel.

When you run high nitro it creates high heat in the motor so what you gain with the nitro won't you lose to the heat created .

 

[Jim Allen]

If the fuel functions correctly or does not function correctly depends on many factors which may be beyond the control of most boaters. The design of pipes, heads, transfers, inductions & exhausts, to name a few must be within resonable correctness for exotic fuels to work in any engine.

Ask yourself, why some present day large displacement engines are burning holes in piston crowns? Is this a fuel problem or is there something very basic that is wrong in the engine's design?

Jim Allen

Could it be a piston and head button chamber problem , Maybe a thicker piston to handle the heat of high nitro and a better head button chamber that will burn the high nitro fuel.

When you run high nitro it creates high heat in the motor so what you gain with the nitro won't you lose to the heat created .

No. High nitro generates high heat only when the engine has been over leaned in an effort to get the fuel to burn. Normal head button shapes; flat top hemi types, double bouble types, toroidal types, can be used effectively without generating high heat. In fact, I ran the straight away engine without any water cooling. The oval engine had a .020" water outlet. Transfer geometry must be correct for whatever type of piston crown; flat, domed, etc is used. I never tested any domed pistons, but the flat top piston was .120" thick with the .250" wrist pin hole .332" down from the top. This left a .032" space between the underside of the piston & the OD of the upper end of the connecting rod. If there was a heat problem, the connecting rod would not have been able to run at 32,000 RPM without any bushing & 6 to 8% oil.

The question that should be asked is; do higher speeds require high nitro fuels? A very well known boater by the name of Andy Brown used 60% nitro to set many straight away & oval records.

Jim Allen

 

[ALLAN YUEN]

Joe Will you try run high 90% so Can you afford pay for replace lot of list parts for CMB101RS( TWIN Rigger) :lol: I won't use it so spend waste time because change adjust needle and shims. one thing big problem metal tank will crack inside brass tubes because too COLD liquid

 

[dwilfong]

If the fuel functions correctly or does not function correctly depends on many factors which may be beyond the control of most boaters. The design of pipes, heads, transfers, inductions & exhausts, to name a few must be within resonable correctness for exotic fuels to work in any engine.

Ask yourself, why some present day large displacement engines are burning holes in piston crowns? Is this a fuel problem or is there something very basic that is wrong in the engine's design?

Jim Allen

Could it be a piston and head button chamber problem , Maybe a thicker piston to handle the heat of high nitro and a better head button chamber that will burn the high nitro fuel.

When you run high nitro it creates high heat in the motor so what you gain with the nitro won't you lose to the heat created .

No. High nitro generates high heat only when the engine has been over leaned in an effort to get the fuel to burn. Normal head button shapes; flat top hemi types, double bouble types, toroidal types, can be used effectively without generating high heat. In fact, I ran the straight away engine without any water cooling. The oval engine had a .020" water outlet. Transfer geometry must be correct for whatever type of piston crown; flat, domed, etc is used. I never tested any domed pistons, but the flat top piston was .120" thick with the .250" wrist pin hole .332" down from the top. This left a .032" space between the underside of the piston & the OD of the upper end of the connecting rod. If there was a heat problem, the connecting rod would not have been able to run at 32,000 RPM without any bushing & 6 to 8% oil.

The question that should be asked is; do higher speeds require high nitro fuels? A very well known boater by the name of Andy Brown used 60% nitro to set many straight away & oval records.

Jim Allen

Jim I was wondering if you could explain transfer geometry for us a little.

David

 

[dwilfong]

One evening at the 1998 World Championships in France, Andy Brown was talking about running 90% nitro fuel. We were at the Ukrainian camp, drinking their wine and vodka.

As I remember it, Andy said that it took a headbutton with 4 glow plugs to burn all of the fuel.

This is the best I can remember from that evening. The Ukrainian vodka was very potent.

Al Hobbs

Joey,

You'll need something to get it started, the hard part is making use of it all.

Al,

I've seen one of Andy's "4 plug" motors, might have been the only one.



B

At the Winternats Dick Jones showed me a 3 plug head he has run. Need the plugs to burn all the nitro up he said.

David

 

[Joe Warren]

Jim to you consider us to be on edge with 65 percent? It has became a norm for me?? Many run 65 percent in there boats. I have never been under 60 myself.... 70 percent even seems to be safe? If you can afford the high wear on parts ticket that follows. Many say there is no performance difference from 50-65 But If you have your boat set up correctly & Can prop up there is a Huge Advantage in HIGH Nitro Fuels.

I can't say that one fuel or another is on the edge. I have a fuel formula book that dates back to 1988 with various fuels that were tested on the dyno & at the lake. 65 nitro, 18.5 men, 1.5 prop, 15 oil ran 84 MPH in my .90 engine. 75 nitro, 10 prop, 15 oil ran 88 MPH. 80 nitro, 12 ethyl, 8 oil ran 92 MPH. The increase in nitro didn't make the engine turn faster, but it did increase the torque & therefore the HP.

If the fuel functions correctly or does not function correctly depends on many factors which may be beyond the control of most boaters. The design of pipes, heads, transfers, inductions & exhausts, to name a few must be within resonable correctness for exotic fuels to work in any engine.

Ask yourself, why some present day large displacement engines are burning holes in piston crowns? Is this a fuel problem or is there something very basic that is wrong in the engine's design?

Jim Allen

From my experience as you increase nitro percentages You Must lower compression ratio. Each fuel percentage has a ideal compression ratio it likes to operate at. Many May Not know? But on the days you race & the Air Quality is BAD, You can regain the Air back buy going to Higher Nitro, the added Nitro will Produce More Air when compressed since it is a oxygen bearing fuel.. AS for the Rs101 Burn piston problem, they Must have a total piston/bowl volume of 1.0cc, For those that dont find this number the engine must be operated on very low nitro. I run 1.0 cc 60-65 percent fuel in my 101`s & try to get the engine to clean out on the pipe & needle flowing 40 or lower on a blood pressure type flow meter. If you must flow a high number (50-65) to get the engine to clean out. the engine or the pipe size & length, Head buton size, Squish clearence, are out of tune...... the engine will not Live with High Nitro & a Stk Head Volume Size...... Steve wood has the numbers & the tools to correct the volume sizes for most CMB engines.

 

[dwilfong]

As the ex timing goes up the chamber size will come down. There is no magic number for the volume on a eng. That is unless you are running stock timing numbers. Then what are stock numbers every time you change the P/S the numbers can change. If you are going to run HIGH nitro you need to do your home work. Check the numbers or you will PAY the price.

It is easy to come up with a head volume number but is it the right number????

You need to know the whole story be for you jump into the pond with High nitro.

David

 

[Joe Warren]

As the ex timing goes up the chamber size will come down. There is no magic number for the volume on a eng. That is unless you are running stock timing numbers. Then what are stock numbers every time you change the P/S the numbers can change. If you are going to run HIGH nitro you need to do your home work. Check the numbers or you will PAY the price.

It is easy to come up with a head volume number but is it the right number????

You need to know the whole story be for you jump into the pond with High nitro.

David

I have backed off on nitro Before & replaced it with methonal to add more refrigerant to the fuel. The Big Block CMB`s is about running Hard & Fast & keeping the Plug Happy!!!!! If the plug is Happy the Rest of the Engine is Too. & If your boat is Hauling ass while this is going on You have a good Volume Size....... as funny as it seems the size of the engine is most of the time a good bowl volume size too.If you are running 60-65 percent nitro`s, there was a time I would shim the head button to the moon to find a diff compression, Today I find that it is much better to get the volume correct & try to run minium squish clearences,

 

[Jim Allen]

Joe,

You DO NOT want to DECREASE the compression when using nitro above 70%. This will cause you to lean the needle which always results in high heat. Smaller diplacement engines can tolerate this but larger motors will not.

You DO want to INCREASE the compression (advance the timing), use the proper ignitor to start the burn (ethylene oxide) & significantly RICHEN the needle.

Main transfers that have the wrong geometry ( aiming the incomming charge in the wrong direction) will cause pistons to be very easily holed.

Jim Allen