BangShift.com Approved: Nitromethane on a Budget With a Carb and Stock Heads!

[A/Fuel]

Re: BangShift.com Approved: Nitromethane on a Budget With a Carb and Stock Heads!

Propane huh? Was this an injected engine with some kind of regulator attached to a tank? Could you tell us a little more how this was set up? It sounds intresting.

[dieselgeek]

Re: BangShift.com Approved: Nitromethane on a Budget With a Carb and Stock Heads!

Propane huh? Was this an injected engine with some kind of regulator attached to a tank? Could you tell us a little more how this was set up? It sounds intresting.

John Beck at ProMachine in Chico, CA builds a lot of nitro engines, apparently runs many of them this way.

[A/Fuel]

Re: BangShift.com Approved: Nitromethane on a Budget With a Carb and Stock Heads!

I don't know anything about propane, except for my grill.
As I'm sitting here thinking about it though, I imagine the oil would stay cleaner after a warm up, I'm just wondering how long it would take to get some heat. I've tried gas but for the most part use a gravity fed alcohol, and we carry that with us anyway.

[horsewidower]

Re: BangShift.com Approved: Nitromethane on a Budget With a Carb and Stock Heads!

No, DG, wasn't John's set up, but it was John's shop. When they had trouble initially starting it on the propane, John jumped up and dumped alcohol in it.

The guys built a manifold that had spray nozziles above each injector stack, They connected that by a hose to a 5 gallon grill tank. Hand held the nozzle manifold over the stacks until it was running then switched over to Nitro. They simply regulated the flow by opening or shutting the supply valve.

[cnitrofumes]

Re: BangShift.com Approved: Nitromethane on a Budget With a Carb and Stock Heads!

Had one guy say you couldnt warm a cast ironhead using alky.....not enough heat !!!
If it's running it's creating combustion....combustion = heat...... I lean my alky drip as soon as it's running solid to help build heat and keep the oil clean. I've had zero trouble starting since I stopped priming with gas.
Lots of fuel Harley guys fog it with gas until it fires and then throw on the NITRO......seem a bit dangerous to me.
Most of the Nitro car guys, blown or injected, prime on alky pump off until they know it's hittin' on all 8 then throw on the fuel....seems safer.
Plus my head crew guy, Silent Bob, feels much better not cranking a live bomb on NITRO !!!!!!

YouTube Alky to Nitro....... back to alky warmup video......by myself !!!!................
http://www.youtube.com/user/NITROCYC.../6/tqGyOCUhY7g

[dieselgeek]

Re: BangShift.com Approved: Nitromethane on a Budget With a Carb and Stock Heads!

I liked that last video - very clear to see what you are doing there!

Question, what kind of timing advance do you run on the nitro - and do you have to retard it to run on alky? I've tuned a number of alky engines - never nitro - am curious if you run the same kind of advance the v8 guys run (70*+)... and how that works with the startup fuel?

[cnitrofumes]

Re: BangShift.com Approved: Nitromethane on a Budget With a Carb and Stock Heads!

I've had this problem posed by one of the spray it with gas and let it rip guys..."the lead required to run NITRO will cause the engine to detonate on alky"

First...alky has much more detonation resistant qualities than gas...period.

Second...it's absolutely idle only....no load....ever. Wacking the throttle on a fixed flow IV system will only backfire the motor.....the suction / gravity fed nozzles have no way of following throttle position.

Third you have the luxury of running it as fat as necessary at idle on the IV to keep it burning fuel and not parts.

Right now I run 45 deg of lead. The majic number according to the previous owner is 57 deg @ 98% NITRO with a .280 main jet in the carb. The stock ironhead chamber is much like the early cast iron hemi chamber.....lots of room for fuel.
Add to this the high tented piston design and flame progress is slower than a squish head with flat top piston....all of this adds to slower burn and higher ignition advances both tolerated and necessary for complete burn.

My old 526 ci 426 style hemi with full factory chambers on alky with 11.5:1 comp ratio liked 36 degrees of lead on alky.
Unlike my buddies BAE Fatheaded 526 with shallow 90cc chambers and flat pistons and the same fuel and compression would only tolerate 29 degrees of lead or she would start banging the bearings out from detonation.

Correct ignition lead is based on all engine build and tuneup factors.......I like to look at the heat on the sparkplug ground strap....color should stop right at the bend.....any less not enough lead.....any further and too much.

At any case....within reason...the motor should tolerate a little more timing at idle no load without risk of damage.

[A/Fuel]

Re: BangShift.com Approved: Nitromethane on a Budget With a Carb and Stock Heads!

A couple more questions for you. What kind of compression ratio and cam duration do you run now? Do you ever check your cranking compression?
Is your evidence of nitro burning slow, solely based on 45 degrees+ of lead?

[cnitrofumes]

Re: BangShift.com Approved: Nitromethane on a Budget With a Carb and Stock Heads

A couple more questions for you. What kind of compression ratio and cam duration do you run now? Do you ever check your cranking compression?
Is your evidence of nitro burning slow, solely based on 45 degrees+ of lead?

Harley Davidson timed these Ironhead motors at 45 degrees full advanced with stock compression ( 9.5:1 or so) on leaded GAS !!!! On the highway !!!! With two riders !!!!! The stock flywheels have a TCD slash and a 45 BTDC mark !!!! The reason is the chamber is huge....volume at TDC is big....lots of fuel to burn...plus way better gas back in the 60's and 70's.
Most modern day rebuilt ironheads lower the comp ratio and back the total advance back to around 40 to 42 degrees to avoid pinging.

I don't have cranking pressure numbers.....I use cylinder leakage to determine engine health.
I believe the comp ratio to be close to 12:1 and I'm not sure of cam timing.
Remember.....this has a carb....so it's tough to raise the dynamic compression by accident like in an injected fuel motor by adding fuel. I'm not sure when or IF I'll ever go all the way to 57 deg advanced. I will have to sneak up on it and see signs that it will tolerate it. The last rider was a good 80lbs lighter so my all out tuneup will be different from his I'm sure.

I don't profess to be any of a NITRO guru....this is my first NITRO powered outing where I call all the shots.

I have observed that NITRO has a staircase style tuning ladder.
You can have a 3000HP 20 GPM blown fuel Hemi or a 8000HP 100GPM blown fuel hemi.....same blower...same motor....same timing......same fuel mix......just different fuel volumes. All along the way there are happy tuneups and mad tuneups !!!! NITRO carries it's own oxygen so it can go from happy to fat to boom to lean...to happy to fat to lean to boom...over and over again without warning.
Gas is either lean or good or sooty fat.....
Alky has a much wider range but almost the same....only difference is way lean on alky almost won't run...kind of saving itself....ALMOST...if your lucky.

NITRO... can go thru lean...boom...happy....fat....boom...happy...boom. ..over and over again making HP higher and higher at every "happy" and shrapnel of everything everywhere else.

[A/Fuel]

Re: BangShift.com Approved: Nitromethane on a Budget With a Carb and Stock Heads!

All good points, and it's totally cool you are doing this. A n/a nitro engine in my oppinion is one of the hardest engines to get a handle on, but once you do, you'll never go back to anything else.
A couple of things to think about though: Once you get the air/fuel ratio correct, you will seldom need to mess around with it. I try to resist when ever possible. I only look at the weather for timing.

[cnitrofumes]

Re: BangShift.com Approved: Nitromethane on a Budget With a Carb and Stock Heads!

I'm used to blown and injected tuning....have no idea how much of a change one jet size makes on this n/a carbed NITRO deal. Standard jets change in .010 increments.......270..... .280....... .290 ....etc.
I figure once I have my top mph tuneup I can leave the main alone and tune by timing....hopefully.
The carb bowl requires exhaust removal first making it harder to jet up and down than normal.

[Barry Donovan]

Re: BangShift.com Approved: Nitromethane on a Budget With a Carb and Stock Heads!

I like to look at the heat on the sparkplug ground strap....color should stop right at the bend.....any less not enough lead.....any further and too much.

clever. one less gauge...

interesting to use a harley, the engine is delayed by engineering, the crazy fuel is welcome there (safety built in)..

those v8 guys and nitro. crazier than I'll never be.

[cnitrofumes]

Re: BangShift.com Approved: Nitromethane on a Budget With a Carb and Stock Heads!

I like to look at the heat on the sparkplug ground strap....color should stop right at the bend.....any less not enough lead.....any further and too much.

clever. one less gauge...

interesting to use a harley, the engine is delayed by engineering, the crazy fuel is welcome there (safety built in)..

those v8 guys and nitro. crazier than I'll never be.

Some think Harley's "delayed engineering" is what makes it so potent and happy on NITRO.......

A buddy of mine who went to a Harley mechanic training course said the original design of the engine was used to power a water pump which had to be pull started out in the field.....the odd firing order made it perfect for starting at low cranking rpm agaisnt a load.......the first cylinder fires...then the second.....then a dead cycle to let it gain inertia....then fire the first...on and on.....

A Harley engine has two pistons. The difference in the Harley engine is that the crankshaft has only one pin, and both pistons connect to it. This design, combined with the V arrangement of the cylinders, means that the pistons cannot fire at even intervals. Instead of one piston firing every 360 degrees, a Harley engine goes like this:


A piston fires.
The next piston fires at 315 degrees.
There is a 405-degree gap.
A piston fires.
The next piston fires at 315 degrees.
There is a 405-degree gap.
And the cycle continues.


At idle, you can hear the pop-pop sound followed by a pause. So its sound is pop-pop...pop-pop...pop-pop. That is the unique sound you hear!

It has been said Harley owned the flat track races because it had a tendency to stay stuck coming out of the turns because of it's unusual power cycle......

Even the most advanced Top Fuel Harleys still use a common crankpin and odd firing cycle....it seems to work nicely with the compression sensitive nitromethane.....

[cnitrofumes]

Re: BangShift.com Approved: Nitromethane on a Budget With a Carb and Stock Heads!

http://www.facebook.com/NITRO.CHUCK#...&id=1105466410

Found this BAD LARRY red white and blue HARLEY DAVIDSON golf cart !!!! Single cylinder....2 stroke....built in 1975 !!!!
This should serve our team well while still not being too much newer than the tow rig or bike....lol.

[cnitrofumes]

Re: BangShift.com Approved: Nitromethane on a Budget With a Carb and Stock Heads!

NITRO HARLEY UPDATE.....
Quickest pass so far was a 10.74 @128mph....1.8 60ft.....
http://www.youtube.com/watch?v=kxgnVpKjrfo
Carbed NITRO means vacuum has to draw fuel, there is no ready made pump pressure so starting line idle and clutch settings are very critical to 1/8 mile performance.
NITRO is a heavy fuel compared to gas or alky so it's even harder to get the right volume.
We use two styles of enrichment circuits to assist with fuel delivery.
The first one is basically a NOS solenoid looped between bottom of fuel bowl and the top side of the carb in front of the throttle blades. A button or timed switch and a metered jet controls this circuit which is normally off by the 1/8 mile mark. Engine vacuum draws fuel from orifice until solenoid is deactivated.
The second is a dump or "60ft" can. It's a can that holds 2 to 6 oz of fuel at a height relative to the top of the carb that wont allow it flow until it sees engine vacuum. When the throttle is pinned wide open this can "unloads" thru a metered jet and is usually gone by 60ft or a little later.

This is what happen yesterday with both circuits on at the hit of the throttle....
http://www.youtube.com/watch?v=PQ0kmuH3pUI
The solenoid jet is a .188....the dump can a .125.....add that to the .125 idle jet and the .270....that's a total of a .708 sized hole flowing 95% NITRO into a 1957 designed cast iron engine....no wonder a 40hp 2 cylinder gas engine becomes a 250hp NITRO BURNER !!!!!!