flsprophet

I have a brand new axial .32 and am planning on running it on 30% nitro. I was wondering what brands people prefer and why. I was thinking about O'Donnels or Byron but all suggestions and tips are greatly apprieciated.

nkbrisson

O'Donnels is a great fuel, but if you plan on running 30% in the 32 you might want to had a head shim, it will be easier to tune and your engine will last longer. If you don't add a shim stick with 20%, your engine will last a long time and tunning will be easier.

snowbl!nd

25% O'Donells. As nkb said, if you go to 30% you may need an extra head shim.

gtsum

I ran 30% odonnell with a os r5 cold plug...I never messed with a shim and it ran great...4 gallons through it and no leaks, good temps, good compression, etc (not in the lst2 anymore, but still have it and it is still in good shape)

nkbrisson

I'm not saying that the motor wont run on 30%, it will run good, but its like chaching the timing on a car, take 89 octane fuel and 91+ octane, some cars will run like crap on 89 when they are timed for 91+, its the same thing in a nitro, you basically have to change the timing to accomidate the 30%, most engines are set to run 20% to 25% stock, add a head shim when you increase nitro and remove a head shim if you go less nitro, it will intern make your engine run better and last longer.

gtsum

I hear ya...a lot of people do just what you are saying (for those reasons) - I have never tried it and all of my BB engines run 30% with a cold plug (either mc9 or os r5) and they all have run good...maybe I will try the shim thing on my next one....

89ram

i use 20-22.5% fuel with good results in my .32

Dil

going off the topic, i have an os18 and i use 5% nitro, its my home mix and it works great with good temps, plenty of power for wheelies as well!!,

i agree with the thing about head shims!!

tommythecat

My Feedback: (2)

Wow 5%

:O

rcsavager

This is an odd thread. Coincidentally, I called Axial 2 days ago and had asked them that very same question. My last engine was a SH .28 8-port and it required a shim above 25%. In asking Axial's support division they claim that no shim is required at all and that it can comfortably run up to 40% without shimming. So I guess my concern here is the propogation of unsubstantiated rumor mills. What proof and/or experience can you stand on to say that you know more about this motor than the manufacturers? Don't take it too personally (really) but without ANY comments in this thread from ANYONE claiming the other end of the spectrum you're advising hobbyists to shim a motor that the makers say doesn't require a shim. I can see your theory but I see no evidence of experience to show that NOT shimming the motor head would make one ounce of difference. Short of dyno-testing both options and providing read-outs related to performance and longevity you're claiming to know more about the engine than Axial.

Again, I mean no disrespect but somebody has to stop the propogation of "facts" when there is no real-world experience behind them. I'm sorry to step on the thread but I own the Axial .32 Spec 1 and run 30% through it. After 5 gallons it's running like the day I bought it. In fact, I bought a second of this motor 2 days ago from StormerHobbies for $186/shipped. The intention with the next one is to run 40% Blue Thunder HP8 in it for racing in the spring. At that level of nitro under race conditions/settings your theory should have my motor in pieces by the end of the 2nd/3rd race. If the thread is still alive in the spring I will gladly link to a full review in RCUniverse.

nkbrisson

no offence taken, but you don't know me for one and you have no right to turn around and say that I have no (real world) experience, i will beg to differ on that, for one i never said that the engine wouldn't run on 30% just said that it would run better if you shimmed the head, and yes most engines can and will run without shimming the head up to 40%, but this is like advancing the timing, and would create more heat, shim the head, bring the timming back and your temps will be more controlable and you will be able to get more power out of it. so before you start saying that i create propoganda you get you facts straight and stop accusing people of something you no nothing about..................

rcsavager

I believe I have EVERY right, and even a responsibility, to voice what I did. I stated that you, nor anyone else, GAVE any substantial facts, proof, or anything else to back up your claim. I on the other hand acquired my information directly from the manufacturer of the item in question and they tend to disagree with your statement. So what I would require to be convinced otherwise would be PROOF of your side. I'd shim my motor in about 2 minutes if I had ANY indication of the validity of your claims. So again, where is the proof, real-world experience, etc. Show me ANY article that backs up your claim and we'll all be smarter from it. Until then you're just bucking the fact that I called you out on your claim and you have nothing, so far, to prove the matter otherwise.

Again, I don't mean to offend anyone but simply to keep all claims, tech tips, etc in the REAL world and not branches of the rumor tree. And again, I see the logic in your theory, what I asked for was ANYTHING to back up your claim. You either have it or you don't. I want to make sure that the money spent for the love of my hobby is well-spent and not diluted, damaged or diminished by false claims. Please, see my side of things here. If you know something you think I don't then EDUCATE me. Don't stand on a soap-box telling me how little I know about you. Do me, and others, the benefit of knowledge beyond the capabilities of the manufacture. If I'm wrong don't just stand there saying, "you're wrong now shut up and sit down". SHOW me otherwise so we all gain in wisdom. I don't see how I could make my point any clearer here. Lastly, it was NOT an attact on your or your knowledge. It was intended to have you SHOW me that what you say is true instead of you telling me how you "ass-u-me" that I know nothing about what I've spent thousands doing. I "ass-u-me" nothing of your knowledge or experience. I simply challenge you to back up your claim that the sky is blue before I take the word of a stranger.

nkbrisson

If this isn't enough information to back up my theory, then I really don't now what is. Here is the link that this was taken from, and there are many more sites that state the same as this one. As well as many tuning books that all state the same. So next time you say that I don't know what the F$&# i'm talking about, you better think twice as i can always back up what i'm saying.................

http://www.*********.org/cars_eng-tuning.htm

CHANGING FUEL
Changing to a higher percentage of nitro fuel sounds like an easy method of developing more horsepower, but it isn’t always that simple. Without getting into all the particulars of nitro fuel, I’ll just say that there is a point where you can have too much nitro. Adding up to 10 percent more nitro than is typical produces more power, but you have to know how to adjust your engine to accommodate the extra nitro. Fuel-mixture settings need to be slightly richer when nitro content is increased. Also, you may have to increase head clearance by adding an extra head shim. The extra fuel introduced into the combustion chamber increases compression by adding non-compressible matter; this also increases cylinder pressure during the combustion process, which may cause detonation. Detonation occurs when the fuel explodes instead of burning, and that can cause internal engine damage. The extra head shim will likely prevent detonation when fuel with higher nitro content is used.

A final note about fuel: fuel with a lower oil content (for manufacturers that actually disclose the amount of oil in their fuels) should be run with a richer mixture setting. This doesn’t so much relate to performance as it does to the benefit of the engine. Conversely, fuels with higher oil content have the extra lubrication that allows a leaner mixture setting with less risk of engine damage. Fuels with a lower concentration of lubricant are intended for competition use by experienced engine tuners. These fuels will make marginally more power because the lubricant that’s removed is replaced with power-producing nitro and methanol. Evaluate your tuning ability honestly before you run out to buy fuel with a lower oil content.



HEAD SHIMS

Engines are essentially air pumps. The engine takes air in, mixes it with fuel, and then the mixture is compressed and ignited. The additional pressure created by the burning fuel increases by a factor directly related to the amount of compression: increasing compression increases power output. But there are limits to the compression an engine tolerates. Too much causes the fuel mixture to combust too quickly, and that returns us to the same detonation scenario of an excessively hot glow plug.

The amount of compression is determined by the number and thickness of the shims (gaskets) between the cylinder head and the top of the piston sleeve. Well, it’s determined by many other factors, but the only one easily changed is the head clearance via head shims. More shims = less compression; less shims = more compression. Removing or replacing shims with thinner ones increases compression. Some engines have only one shim, so it isn’t advisable to run without a shim at all. Moderation is the key. Go slowly, and make small, not drastic, changes that will minimize the risk of damage to your engine. First and foremost, be sure the piston won’t hit the cylinder head if you remove a shim (or shims).

You can also change compression with glow plugs. Some manufacturers make a longer glow plug that protrudes slightly into the combustion chamber, effectively reducing the area in which the fuel mixture is compressed. This area is already small, and the little extra space occupied by a longer glow plug will raise compression. This is not the most desirable method, but it can be used on engines that have only one thin head shim. It’s unlikely that the longer plug will even come into contact with the piston, but just to be safe, check the head clearance before you install a long plug.

nkbrisson

Here is yet another link to support my theory.

http://www.mecoa.com/faq/compression/compression.htm

rcsavager

Ok, now we're getting somewhere and EVERYBODY reading this will be more informed. Let me drop in this last post just to save a mouse-click for members with tired fingers from racing but first let me comment on something that is being overlooked and then I will let the entire matter rest and allow others to base their decisions on what is best for their application.

The overall theory that will be quoted below is quite sound and makes perfect engineering sense. Here's where we'll all fail to find information. We have no idea of the actual timing and/or compression ratio of the Axial .32 engine. (Although that will be a call I'll make Tuesday moring to them). What I can say from experience with this engine is that 30% Blue Thunder does not "ping". So to assume that it would require adjustment with a shim is premature at best. I do however agree with both articles and their claims. What we lack is how this applies to the Axial .32 Spec 1 engine. I can say that at 5 gallons of fuel, and additional reviews by other users, that the motor runs fine on 30% (in my climate with proper tuning) without extensive wear on the sleeve, crank, pin, rod, etc. What I cannot say at this point is what will happen when the new motor drinks 40%, low-oil racing fuel. Racing fuel is MUCH different than "sport" fuels as it has much of what the second article warns you about. The oil content is lowered, semi-replaced by a synthetic oil engineered to adhere to the metals to maintain proper lubrication, and with the higher percentages makes for some dangerous matches to burn up your motor with if you're not VERY careful in your tuning and CONSTANTLY monitor engine temps.

The main thing I hoped for was how the "basic" information of engine tuning related to the Axial .32 Spec 1 engine. Even though it's relatively new in the market it has been difficult to find that "real-world" experience from racing-level hobbyists about this engine. I only speak from how my climate and fuel choice has treated me when the engine in race-tuned. What will happen at 40% in combination with a racing-level fuel is still unknown. As a standard, nkbrisson has hit a very valid point in a broad sense. GENERALLY, these rules are the basis of nitro motors and should be considered when forming your own opinions for your own motors.

Understand that you sir were never doubted as I wanted to see how THIS motor acted when put up against the "standard" in engine tuning. Again, you've shown no "REAL-WORLD" information of this topic and THIS motor. The basics are the basics are the basics in nitro tuning but every motor is different. What the OP asked was how it all related to THIS motor. In that respect you don't seem to have the experience in THIS motor as your position and claims suggested. So now I ask that you sit back and let the guys that push these motors to the edge take over and we sit quietly in the background and learn more about THIS engine. As previously stated, during the spring racing season this particular motor will be pushed to it's limits and I will be more than happy to fully, and critically review this motor for all to take what I've learned and use it as a basis for making their own observations and decisions. I'll NEVER claim that my way is the right way but I will give others the benefit of my experiences so we all can enjoy every ounce of the hobby we love.

Thank you all for sticking through the madness but nkbrisson has provided a great platform for you to help you understand how things work and how they might apply to the Axial .32 Spec 1 engine.

Happy hobbying all....and to all a long engine life.

nkbrisson

Well that is very well said, and I agree with you. so now lets just sit back and relax on the topic a bit and let people run them and then give us all there info from there experiences and base all facts from the (real world) experience to set up a guide on how to tune an axial.32 to run on different types of fuels in different types of climats. So let this slightly heated discussion cool down and see what others have to say on the matter.

Chronic

When you call Axial tuesday morning also ask them if they will warranty an engine that was run on 40%, extra shimming or not. I don't know the answer, but I'm pretty sure it will be no.

A tech guy saying something is okay is alot different than a warranty department saying it's okay.

rcsavager

Heh, heh. Good thinking there boss. Look forward to asking JUST that question now. I wonder where their "line in the sand is" on that subject. But with all due respect to Axial here, they built one HELL of an engine for it's price point. At 8-ports you're talking about some fairly serious torque as well. I think I can justify that claim with knowing what it can do running 30%. They also suggest a 19/47-49 gearing to prevent that low-end torque from ripping off your wheelie bar but then again you're at the mercy of tuning and piping at that point. What they'll stand behind with no set-in-stone limits is indeed something I'll inquire about. If I'm carrying their name on my truck I want to KNOW that they are worthy of my support and exposure just as anyone else would be. Their site lacks a LOT in content; ie. forums, instructionals, manuals, etc but they assure us (as all sites do) that the content is "being updated". We'll see the fruits of those labors when it blooms but having their customers come together in RCUniverse gives a place un-jaded by the manufacturer to talk more solidy about what does/doesn't work in their product line. Sad to see them so active in other forums (avoiding URLs out of respect for RCU) and not here where there is so much to offer the community. Maybe discussions like these will prompt them to expand their marketing/exposure here as well. Maybe I'll PM one of them a link to this thread and see what they have to say to new/existing owners of their pinnacle performance engine.

Message delivered via PM to Axial in another forum. Let's leave the light on for them.

Chronic

I'm really surprised the tech guy told you it's okay to do so, I doubt the guys in charge of the warranty are going to agree with them. Myabe, maybe not... but since your plans are to go that route I would ask. It would suck to have a premature engine failure because of manufacturer errors and then have Axial turn around and deny the claim because of nitro content.


Who actually manufactures the Axial engines? I know they are the same as the RE Surefire .32 and the HPI K4.6(.28), but I've never heard who makes them.

rcsavager

A foggy guess would be SH. I have been told that SH makes the HPI motors as well as others that are rebranded to their individual distrubuters. With your information and mine put together kind of point back to SH. The only thing that leaves a gap is the fact that I bought the largest SH engine they make straight out of Hong Kong (still have the funky green air-mail wrapping paper from the shipment). The point to ponder is if SH makes 5.3cc engines why don't they sell one under their own name? I'd be interested to know that answer as well as I'm a big fan of cutting out the middle-man and getting the "juice" straight from the man that made it. (Hense the Hong Kong shipment). Incidentally, I wouldn't recommend ordering an SH engine as I have their .28 sitting in my closet with a dead one-way bearing and roto-shaft that I don't feel like waiting another 2 weeks to get it replaced. And that motor made it through 3 tanks of break in and not a drop since. Might make a nice lamp though with it's bright shiney head-sink. [:'(]

ahotrodder

I was wondering if you have heard anything back from your message or received any info from your Tues phone call? I ask because I plan on buying one of the .32's this spring and I also agree with what you have said about the % of nitro. I have some experience with nitro from drag racing a few years back and agree that the % should be based on what the engine was built to handle.

rcsavager

I am told that they only warranty 20-30%. I'm using Blue Thunder 30% Racing Formula and have no complaints so far. Other than to seriously consider a roll-cage again. This motor is NUTS!! [X(]

89ram

i've used 20% topfuel and 15%wildcat in my .32 axial without any ill effects. i also like to add a couple tablespoons of sig castor oil per gallon for a bit of extra protection.

rcsavager

There is no substitute for preparation.

As a side note to hobbyists considering this motor: CHECK, don't assume, that your drivetrain can take this beating BEFORE you buy the motor that will prove you wrong. The low-end torque of this motor just munched a 4-gear spider set in my rear differential. If you land with the power on or the brakes applied be prepared to do some wrenching. I was just bootin' across the back yard when she when FWD on me. If you have worn cups, shafts, bearings, etc that need ANY attention I'd recommend doing today and getting your new motor tomorrow. This engine WILL find the weakest link in your drive train and then will commence to pulverizing that part to it's death. KNOW what you're about to drop this motor into. This thing is not for the faint of heart.