nitromethane and the small block chevy:

Can a stock small block chevy take some nitro?

If so, how much?

 

I think I recall seeing an article (with pictures) where the champion speed shop guys were running nitro in a stock block, until they split the block it half!

 

The answer is yes a little but it's not that simple and the gains of using a little (under 20%) would be minimal if at all. Consider air/ fuel ratios for a minute. gas= 12:1
methanol= 6:1
nitromethane= 3:1

Now think about mixing them.

Posted using the Full Custom H.A.M.B. App!

 

Dont worry about small blocks, just go ahead and add some to your Toyota Prius. Always with these retarded posts, half of which you could study and figure out for yourself.

 

Why???????

 

they are common in Jr. fuel. although the modern ones look like sb2 motors. theres only a few pictures of mid 60s dragsters running sbcs...theres that red cacklecar with a traditional looking sbc mill. early 60s a/fd marked dragster, gotta be 70%+ based on the flame on the YouTube videos

 

Dump some model airplane fuel in the gas tank.
You'll like it

 

Just spike your gas with 20% toluene.Google "rocket fuel",thats what its called. I used to do that with my nitrous equipped 901cc polaris sled.smells good too.

 

now are we done insulting the man? he just asked a question.

however, the question that begs here from the OP is...

what is your intended purpose?

simply put, nitro is for drag racing. if you have no plans to commit to building a nitro-specific engine/powertrain/race car chassis, then you will have some expensive lessons coming your way

i am not a drag racer..... yet.

i hope never to be a "typical" modern-day drag racer obsessed with low et's and 60 foot times at the expense of real racing for fun

i am not a professional engine builder. i'm more a casual student of drag racing history

i too share a similar interest in the "nitro learning curve"; so here's some tidbits that i have found in my study of this subject so far. just keep in mind that i'm no expert here

there is nothing stock about an engine tailored to run nitro

nitro is an explosive and the aforementioned 3:1 air/fuel ratio is required to prevent detonation, which is catastrophic, and not just confined to what happens inside the crankcase. life and limb are at stake.

lean is BAD

low percentages are actually harder to tune and get it right.

as mentioned earlier, nitro carries an extra oxygen molecule and will lean out when added in percentage to a setup that works great on straight methanol.

for any given 10% increase in nitro load, you must restrict the fuel return bypass jet by another .010" or so in a constant flow mechanical fuel injection system

nitro is extremely load sensitive, and will detonate when unexpected changes in engine load occur. cylinders can also pick up and drop off

constant flow mechanical fuel injection is a must, and flowed by a professional for your application. pump selection is also important. a Hilborn PG175-2 would probably be a good start.

magneto ignition is almost a must to fire the incredibly dense compressed air/fuel mixture.

conventional electronic type ignitions should probably be avoided unless you purge the engine after every run; as a spark could occur in a cylinder when the ignition is first energized, and if any nitro is present, catastrophic things will happen (imagine a cylinder head as a projectile).

you shut the fuel off to stop the engine; never never never the mag kill switch!

aluminum rods are your best bet to survive the tremendous shock load, with very wide open clearances in your bearings. 50 wt racing oil too, changed every couple of runs

forged pistons go without saying

most guys "back then" ran Milodon girdles that tied the main caps to the pan rail on the center three mains. you could probably get by with splayed billet steel main caps and a modern "flat" girdle that does not extend to the pan rail

forged crank is a must, nuff said

roller cams are also a must. remember you are opening and closing the "doors" on explosions (albeit controlled ones, but far more violent than gasoline). valvetrain and valvesprings must be up to task also. a rev-kit is a good idea as well

nitro engines of about 390-400 CI probably should run about 6:1 static CR in blown applications with a 6-71 gmc running 20-25 percent overdriven (16-17 lbs boost)

rod/stroke ratio is also fairly critical. you want the piston to come away from TDC fairly quickly for better detonation resistance. 1.6 is relatively ideal for this. that's a 3.75 stroke with a common 6.0 inch rod in an SBC

a 4" bore will want about 32-35 degrees of ignition advance total

a cam profile with late exhaust opening timing is good for making optimum power (80 to 95 degrees). if it occurs too late detonation can occur at BDC. study the old cam catalogs from the '60s and look closely at their "Top Competition" roller grinds like the Isky 550 Super Le Gerra (intake 57-93, exhaust 93-57, .540 lift .030 lash hot, 330 degrees duration)

 

So let's bring this thread back to life with a similar question:

We have an alcohol injected SBC we run at the Meltdown event. Since the MDA decided to run night races on the Saturday we want to put on a bit of a flame show through the zoomies. So let's ask the same question with a bit of a twist:

How much nitro do we need add to create the light show / header flame effect we are looking for ?
What changes do we need to do regarding timing, mix, hard parts etc - to keep it safe (ish) - we still want to make a run. Improving performance is not a major concern. Not blowing it up - is

The combination:
358 sbc on alcohol
Roller cam
Steel rods / forged pistons (Yah I know steel rods are not good with Nitro)
13.6 - 1 compression
Iron Eagle heads
Hilborn mechanical injection
Vertex magneto

 

Depends on how it is built. Low does on a mild motor and high dose on a built motor.

If you go everything forged, higher compression and blueprinted, beefing whatever you can an SBC will take whatever dose anything else will handle. We are talking studs, stud girdles O ringed block and etc. then you can really dose it.

@c-10 simplex , @Zig Zag Wanderer gave you some pretty good information.

Here is a thought that maybe you could try for grins. We used to use water injection pumps with methanol that mixed in the air fuel mixture we were already running on. One of the l fellas tried it with some nitro he got from real racer and it worked well. he swore that his car was cutting a fat hawg. I am not sure that it was but it stunk like it was supposed to and his exhaust glowed.

 

I thought it was a new thread again.
Till I saw my post

 

LOL my day was going well until you pointed that out. Thanks a lot.

 

While I was racing I used to enjoy Dale (Tom) Taros

 

I like it; its way way more fun than alcohol (methanol) or gasoline. Much of what is said (above) is BS. Hunt and Cook won the world championships with one. Since they turn such low RPM's they are relatively easy on some things...like valve springs. Let me speak to my numbers on Nitro: We ran 100%, 13 to 1 or so and 60 to 75 degrees with dual 44 amp mags. This was a hemi in 2001 give or take. My blown alcohol mouse motors ran from 1976-1978 replaced by a blown Rodeck...
I wish I had raced nitro from day one!

 

I call foul on 100% @ 13:1 ratio, there’s no way to keep heads on engine or crank in engine under those conditions.

 

Before we had a Blower we had a Steel 355" S.B. Chevy Injected on Alcohol. I bought a 5 Gallon Jug of Nitro and we started off at I think 10-15% We did have a Hydrometer(Sp?) We fattened the Barrel Valve for the idle mixture and reduced the Main pill to fatten it. Our Pump was too small to go past 33%, we could not flow enough fuel. @ 33% on a "Dirty" Tune up we picked up 2/10's We ran something like a 8.38 when we had only ran about a 8.60 prior. But the real fun was the starting line at idle, just pumping the Nitro out the pipes and the Wonderful Smell! Great memories for sure. Oh we did this at the Eagle Motorplex in 1992

 

Would need a complete re-jet. Typical A/F ratio for nitromethane is 1.7:1. Exhaust valve material would have to be upgraded, $48.00 a gallon, If you just dump it in, you will run lean and be low on power. Old wives tale about model airplane fuel, etc..........

 

LOL I am not absolutely sure what the mix is on model airplane fuel. But do know of a model helicopter that runs in nitro, they are like a model airplane without a fixed wing I suppose. I happened to acquire a 5 gallon can of nitromethane in a parts deal back around '03. I had a friend that raced a model copter (I guess its a big deal he went all over the country doing it). I was wondering what I would do with 5 gallons of nitro, I knew that it would get me into trouble eventually. We are talking and I said will your chopper run on nitro and he said it would if he had some. So I figured it was cheaper to give it to him than to keep it. So there is at least one model airplane out the that runs on nitro.

I don't think that top fuel run a 100% charge. I would think that any small block chevy or anything else that you could drive for more then one or two passes would run a pretty low dose. Top fuel cars get pulled down between rounds and rebuilt.

 

The Champian Speed Shop guys ruined a LOT of small Chevy blocks.
BUT...they ran "much" more than a "little" nitro. They kept up and even beat many of the hemi powered cars for many years before moving to the big Chevy.

Mike

 

What's a wives tale?
Model airplane fuel is mostly methanol blended with castor oil and nitromethane. The nitro mix is between 5% and up to 30%, castor oil is from 15 up to 20% . All different formulas for the particular glow plug engine being ran.

 

I love the smell of nitro in the morning.....

 

to get the flame my buddy has to run a 30% mix and runs richer than hell on the a/f mixture but at that low ammount there is no real performance but it puts on a show even in the daylight , he says the performance starts kicking in at 50% , and a stock chevy block can handle 30% , the rods and bearings are another story .as your basically hydraulicing the motor ..

 

30% is about what I was thinking for a stockish small block. I would want a steel crank and forged pistons even at that dose.

I got to stage a *car running @70% once, just staging was a rush, I just can't imagine trying to hang onto it for launch and the next 1300 or so feet.

*AA/FA

 

Really well you don't know shit! We did it many many times! Even a cap full of methanol slowed it down! However please note even 100% nitro is not quite 100% it has a bit of stabilizer in it. However when I raced nitro we used it straight out of the drum! No methanol added! The motor 426 cu in hemi had as much compression as we could build. It took a bunch of work to get it to 13:1 but it can be done. It's actually easier on nitro because it only turned 6500 rpm. You also maybe confused my car (s) were INJECTED not blown!

 

Well gene I would rather be blown than injected.

I would think no matter how hard it is to build it that way that you would want a minimum of 13:1 on a motor running high dose nitro. I think probably the reason that so many nitro motors are blown is to up the cylinder pressure to aid in detonation. That is just a bean theory and nothing that I have proven or read.

 

As an aside...
The biggest (Kaboom) danger is starting one of these things. If its not absolutely perfectly dry when you start to spin it over it will make a small pop...not terribly loud. However the cylinder that has the nitro leaked into it will do amazing things: The small end of the rod will go completely thru the piston top and the remaining end exits out of the block thru the steel sleeve and of course the top of the rod bearing is spread .200! Not that loud... really. Wanna ask how I know?

 

Quoted for the Truth!

 

I am not sure how popular it was but some of the modern fuel altereds actually started on alcohol and switched over after start.

Nitro is not for the faint of heart all sorts of little things can become big things real quick. I wonder what a Donovan block with a picture window is worth these days.

 

We wanted to build an injected nitro mouse it would have been a bad ass! Probably 60 foot like a top fueler, however NHRA nixed that! They are idiots and basically killed the goose that laid the golden egg! Before the good guys at NHRA retired they made good safe decisions. You were treated fairly and it paid well enough to get by (that is if you had a regular job to go to on mondayAM) Well don''t get me started!