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Nitro %'s

Old 06-07-2008, 11:29 AM
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Edfltchr
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Default Nitro %'s

Hey guys I just recieved an order from Tower with 33%Traxxas and other goodies.I was thumbing through the catalogue and saw where Trinity has 35% and O'donnels goes up to 50% nitro.What nitro % can these little engines handle and is there a gain for going up to 50% nitro?
Old 06-07-2008, 01:20 PM
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NitroTherapist
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Default RE: Nitro %'s

I wouldnt go over 35% unless you wanna have premature engine damage. The higher nitro content from what I've read gives you low end torque at the cost of top end speed. Thats why you see off-road racing using 30% and on-road using 20% most of the time
Old 06-07-2008, 01:21 PM
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wjvail
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Default RE: Nitro %'s

Most "car/truck" engines are designed for fuel with about 25% nitro as mixed by volume. The numbers quoted by fuel manufactures today are almost ALWAYS mixed by weight. 25% nitro by volume is about 33% nitro by weight. So when Traxxas fuel says it is 33% nitro, I personally only consider it 25%. With that out of the way...

Our engines can be made to run on 65% nitro and above as mixed by volume but most surface use engines today have a sweet spot at around 25% (33% by weight). I say they "can be made" to run on these fuels because as you deviate from the designed nitro content, modifications have to be made to the engine to optimize the new higher nitro content. Performance will improve as the nitro percentage is increased and changes are made to the engine; however, running 50% nitro in an engine that has be optimized for 25%, without modification, is asking for trouble.

Your question is akin to asking "can I put 5 quart of oil in my Honda if it says use 4 qts?". The answer is yes if you modify the oil pan and there would be some benefit to having a larger oil reservoir. Putting in 5 qts without modification might work but it is asking for trouble and certainly not recommend. Its kinda like that.

Bill

Edited for typos.....
Old 06-07-2008, 02:03 PM
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slayerphonics
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Default RE: Nitro %'s

Boats planes and choppers can run higher nitro, but us ground guys stick with 20 to 30 % mainly
Old 06-07-2008, 02:32 PM
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ProStreetCamaro
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Default RE: Nitro %'s

Alot comes into play when it comes to how much nitro you can safely run. Way to much to even get in to in a duscussion on here. I will tell you I ran over 13 gallons of 30% through my stock savage 25 engine and it was still going when i sold it to my friend.
Old 06-07-2008, 06:52 PM
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Edfltchr
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Default RE: Nitro %'s

Thanks guys I was getting ready to order more fuel and wanted y'alls opinions. Bill I understand the oil pan thing thanks. Guess I'll stick with Traxxas 33%. Anyway thanks again guys.
Old 06-08-2008, 07:35 PM
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black mamba
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Default RE: Nitro %'s

Big blocks should be running no less than 20% and can easily handle 30% because they are designed for it. Always run 30% for maximum performance.
Old 06-09-2008, 05:44 PM
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Default RE: Nitro %'s


ORIGINAL: wjvail

Most "car/truck" engines are designed for fuel with about 25% nitro as mixed by volume. The numbers quoted by fuel manufactures today are almost ALWAYS mixed by weight. 25% nitro by volume is about 33% nitro by weight. So when Traxxas fuel says it is 33% nitro, I personally only consider it 25%. With that out of the way...

Our engines can be made to run on 65% nitro and above as mixed by volume but most surface use engines today have a sweet spot at around 25% (33% by weight). I say they "can be made" to run on these fuels because as you deviate from the designed nitro content, modifications have to be made to the engine to optimize the new higher nitro content. Performance will improve as the nitro percentage is increased and changes are made to the engine; however, running 50% nitro in an engine that has be optimized for 25%, without modification, is asking for trouble.

Your question is akin to asking "can I put 5 quart of oil in my Honda if it says use 4 qts?". The answer is yes if you modify the oil pan and there would be some benefit to having a larger oil reservoir. Putting in 5 qts without modification might work but it is asking for trouble and certainly not recommend. Its kinda like that.

Bill

Edited for typos.....
Bill,
I am a fuel manufacturer and have been for more than 8 years. I know what is going on in the industry and I can tell you that Byrons is the only fuel company that makes fuel based upon weight. Cooper's, S&W, Powermaster, Morgans, etc... all blend by level volume.
Old 06-09-2008, 05:52 PM
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Fuelman
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Default RE: Nitro %'s

Guys,
Everybody seems to like running the high nitro, why? Just about every car engine on the market was designed to run on 16% nitro as its optimal nitro percentage.
If these little car engines were designed to run on 30% nitro, then why do they have a head shim or two in them to make them tolerate 30%?
If you were to take out the head shims and retune the engine, those of you that have been running 30% could easily run 20% or LESS.

Here's some of the benefit of using less nitro:
The same or better power once shims removed and retuned
More runtime per tank
Costs a lot less.
Easier on plugs
Old 06-09-2008, 09:25 PM
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Default RE: Nitro %'s

ORIGINAL: Fuelman
If you were to take out the head shims and retune the engine, those of you that have been running 30% could easily run 20% or LESS.

Here's some of the benefit of using less nitro:
The same or better power once shims removed and retuned
More runtime per tank
Costs a lot less.
Easier on plugs
Agreed, and having gone to the extreme of removing shims (except for the thinnest one to keep a good seal) and then machining the head button to raise compression even further we run our engine on ZERO nitro.

Power is identical to similar car/engine using 25% nitro.
Tank gives 8 minutes compared to 6.
Fuel is obviously cheaper considering we make it ourselves.
One plug was changed in 40 hours of racing.
Old 06-10-2008, 11:53 AM
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Edfltchr
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Default RE: Nitro %'s

Ok guys one more question both motors are 2.5R's in a Jjato and Maxx ,ran absolutely flawlessly on Top Fuel 33%. Just got my order from Tower and it seems I ordered 20%,Now the motors run like crap. My question is does higher nitro content help a worn motor run better?
Old 06-10-2008, 05:11 PM
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Fuelman
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Default RE: Nitro %'s


ORIGINAL: Edfltchr

Ok guys one more question both motors are 2.5R's in a Jjato and Maxx ,ran absolutely flawlessly on Top Fuel 33%. Just got my order from Tower and it seems I ordered 20%,Now the motors run like crap. My question is does higher nitro content help a worn motor run better?
If all you did was fill up the tank and go run the engine on 20% without retuning the engine, then yes, it will not run as well as it did with 33%
You must dial in the engine on the new fuel. You will probably have to remove the shim and then tune them in. They will probably both need to be leaned out to run the 20%.

Higher nitro does not necessarily make a worn engine run better.
Old 06-10-2008, 08:20 PM
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Edfltchr
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Default RE: Nitro %'s

Well never took out the shim tried my danmdest to tune them.Broke the rod on the Jato and cant get the Maxx to run barely at all new plugs checked for air leaks, I'm just confused that the diff in nitro % makes these things run so differently.
Old 06-11-2008, 06:50 AM
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Default RE: Nitro %'s

I don't have a problem, rarely do any of my buggies have the same fuel in them two quarts in a row. I go from 30% to 15% to 20% to 10% and pretty much run whatever I have on hand that are leftovers from blending fuel. Thats all I fly and drive.
Old 06-11-2008, 09:37 AM
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Default RE: Nitro %'s

what do you do if the engine only has one shim? can it still go from 30% to 20%?

Now that Sidewinder has had two price increase in the last 6 months I may switch back to 20% if it really will have the same power as 30% and be easier on plugs. (since plugs are getting $$$ now too)
Old 06-11-2008, 02:06 PM
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Default RE: Nitro %'s


ORIGINAL: JB COMP

what do you do if the engine only has one shim? can it still go from 30% to 20%?

Now that Sidewinder has had two price increase in the last 6 months I may switch back to 20% if it really will have the same power as 30% and be easier on plugs. (since plugs are getting $$$ now too)
Personally, I would remove it and use the lowest possible amount of nitro I could. Tune for crisp and clean and no sagging in a WOT pass and you will be fine.
Old 06-11-2008, 02:34 PM
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Default RE: Nitro %'s

I may have to do that, if it gets the same performance then buying 30% over 20% is just wasting money.

What I've learned here over the last year as gone against everything I learned when I first started getting into RC.
Old 06-11-2008, 08:37 PM
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Default RE: Nitro %'s

ORIGINAL: JB COMP
what do you do if the engine only has one shim? can it still go from 30% to 20%?
JB...I've run a stock standard (with all the shims still fitted) car engine on zero nitro and 20% castor with no problems at all. As to whether you'll have the same power, that depends. If the plug/compression wasn't ideally suited for the 30% then you could end up having more power with the 20%, it's all a juggling act. You'll have to retune though when you change nitro %.
Old 06-11-2008, 09:31 PM
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Default RE: Nitro %'s

I didn't really see a difference when I changed from 20% to 30% anyway. (power wise) One of the things I heard (from the local guys) is that with 30% your engine runs cooler then 20% is that true? (I know I'm not suppose to worry about temps)

Should I switch to hot plugs instead of med when I go to 20%?

Sorry for all the question I just want to know from some one who knows what they're talking about.
Old 06-12-2008, 05:09 AM
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atul
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Default RE: Nitro %'s


Hi Downunder:

I just got a new RB S7 that I plan to run in shortly.

I like the concept of ZERO percent Nitro since I do not plan to race - just have some fun.

My question is: How much OIL percentage do you use with Zero nitro? Is it a simple 80/20 (methanol/castor-oil) mix? Or is the oil percentage less... or more.

Also, are you using straight Castor Oil for the oil or are you using Synthetic?

Any direct ion would be great!

Thanks!

Atul
Old 06-12-2008, 02:39 PM
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Edfltchr
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Default RE: Nitro %'s

So if I remove the one shim under the head on a TRX 2.5 would the head be sealed enough?I know its copper to help seal but would no shim at all make a diff in performance?
Old 06-12-2008, 11:40 PM
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Default RE: Nitro %'s

ORIGINAL: atul123
My question is: How much OIL percentage do you use with Zero nitro?
You need to use a higher % of oil because without any nitro the fuel consumption is quite a bit less. As a rough guide, without nitro we're getting about 8 minutes per tank compared to about 6 minutes with 25% nitro. We use 20% all castor so that's about the same flow rate of oil as using 16% oil in the nitro mix. Castor is used for two reasons, first it's a far better oil especially for the conrod and second, we get it cheaper than synthetics .

Edfltchr
Unless the shim is unusually thick it probably won't make a noticeable difference. Usually a head will still seal without a shim but sometimes they need a bit of lapping to smooth out any machining marks. Toothpaste (not the gel kind ) makes a very fine lapping compound.
Old 06-13-2008, 08:23 AM
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Default RE: Nitro %'s


ORIGINAL: downunder
Toothpaste (not the gel kind ) makes a very fine lapping compound.
Really?[&:] Could I get some pictures of this
Old 06-21-2008, 01:39 PM
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Default RE: Nitro %'s


ORIGINAL: JB COMP


ORIGINAL: downunder
Toothpaste (not the gel kind ) makes a very fine lapping compound.
Really?[&:] Could I get some pictures of this

Here you go!







It's true, toothpaste can be used to 'break-in' engines if you're in a hurry. Put some on the piston and lap it in.
Old 06-21-2008, 02:50 PM
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JB COMP
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Default RE: Nitro %'s


ORIGINAL: SManMTB


ORIGINAL: JB COMP


ORIGINAL: downunder
Toothpaste (not the gel kind ) makes a very fine lapping compound.
Really?[&:] Could I get some pictures of this

Here you go!







It's true, toothpaste can be used to 'break-in' engines if you're in a hurry. Put some on the piston and lap it in.
I meant of it on the engine.

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