Octane Rating

[cruzn57]

My 2 cents

the big names in sprints/ outlaw dirt cars all use methanol, they could use alchy, but choose methanol, why, I have no idea, but it must .....
A. make more HP
B. cool the incomming charge better than other fuels.
C. be higher octane
D. who knows, but everyone else is using it !

 

[turbofabricator]

Preignition with methanol? Most of the problems I have found with Auxillary injected methanol isn't pre-ignition, but in fact detonation (two COMPLETLY different things) When you inject methanol (or any type alcohol) into the intake stream, you rely on the manifold to distribute the fuel equally to all cylinders. You CANNOT do this with a stock intake (Buick turbo). We have an airflow problem in the stock intake, in that the rear cylinders get more air mass than the front cylinders because of the dog house and the high velocity of the incomming air mass under boost. When you add alcohol to the equation, then the rear cylinders get the added benifit of alcohol (methanol) but the front cylinders start to run leaner than they use to. Then you get detonation in the front cylinders. There is a happy medium where too much alcohol is not enough (for the front cylinders in this case) Consider a Top Alcohol dragster, they run how much boost? (60+)and NO intercooler? and No radiator?
I use to build 2,240 cid Unlimited Hydro engines that ran on gasoline and we used what is termed in aviation as ADI or Anti Detonate Injection which was a HUGE spray nozzle that sprayed 50/50 water/methanol. We would go through 25 gallons ADI, and 65 gallons of gasoline (115/145av gas with an addative), 150 lbs. of N2O ("NOSS" for the younger crowd :tongue: ) in just 4-5 minutes. Most boats ran methanol and they didn't have preignition issues. The unlimited diesel tractor pullers in Europe are now running straight methanol instead of diesel and they run OVER 250 psi boost So, I think you may need to re-think the preignition issue, but then again maybe I am wrong, I have been before. :wink:
Now, the concept of Razors kit (I run one myself) is GREAT! In that it allows us to run more boost for a given octane rating, and the poor intake characteristics. The added alky in the airstream corrects the poor manifold design by GM by initially adding the alky where it needs it the most (in the back) but when you start cranking in more and more alky and boost then you are at the mercy of the intake design and nozzle placement. Look closely at the intake plenum designs on turbocharged Formula 1 engines of years ago. There are clues to be had there. We don't have the luxury of plenum designs they have, so just don't expect to keep turning up the boost and turning up the alcohol and going faster without structural problems

 

[Alky V6]

In most, if not all, of the material that I've read on methanol fueling, they specifically mention that 'methanol does not detonate, it pre-ignites'. And from my experience with both of my last engines, both running 100% methanol, I can tell you that they are undeniably, absolutely right. Detonation does not bend piston pins and fold rods in a matter of a few ignition events. Pre-ignition will. I assure you that a top alcohol dragster is running a plenty rich mixture to get the benefit of intercooling by use of the fuel evaporization itself. That is the only way they can run that kind of boost without intercooling. The problem with running that rich of a mixture is that you need a mini welder to fire it off. Methanol is a fantastic fuel, but like everything else in racing, it has its limits. And when you push that limit with methanol, it is unforgiving. Turbofabricator has a very good point on the limitations of the stock intake setup and people would be wise to try and understand completely what he is talking about.

I'm currently reading a book that mentions that running rich mixtures of methanol injection as a combustion coolant will actually promote detonation. It didn't go into detail on the conditions or percentage of combustion coolant to fuel. Just be aware that there are limits out there in your quest for more. And sometimes when you find that wall, things get pretty smashed up.

 

[79Sleeper]

Well i am going to change the mixture to 70/30 methanol /water, as i have learned the hard way that pure methanol has a nasty pre-ignition property when run pure. you may make more power on it, but if it is going to cause pre-igntion, i need to reduce that from happening.

Norbs,
I'm curious, what exactly happened? How was your tune up when it happened timing and AFR wise? What percent of your total fuel was meth and do you know what your egt was? I would think that the second it pre-ignited, the KS would have shown something...

Just trying to educate myself as I run 100% meth injected, and if there is a risky senerio to stay away from, I will!

Troy

 

[79Sleeper]

If you spray just enough methano to quel detonation, you wont have pre-ignition.

If your timing is set up correctly, and are not bouncing off of rev limiters.. you wont get preignition.

I have sprayed my motor to death and never pre-ignited it. Altho I have customers with DSM's that had issues running twin 15's and bouncing off the limiter..

Keep your alky to suppress knock. Not try and over inject.

Get crazy with water.. you'll hydro the motor.

Julio,
How about if you are sitting on the 2-step on the line for a few seconds? Thats similiar to bouncing off the rev-limiter? I suppose then you should have the wire grounded to reduce flow, or it really isn't a problem?

Troy

 

[turbofabricator]

You are correct in regard to running 100% methanol. I was referring to the typical Turbo Buick guy and even the DSM crowd in that it's not the methanol that is pre-igniting, but is usually detonation. No, not the methanol, but the gasoline is. Pre-ignition in a gasoline engine usually burns a hole in the top of the piston due to the pre-ignition taking place at the BOTTOM of the cylinder on the compression stroke when the piston is on the way up in the bore. Pre-ignition doesn't happen at or near TDC because the high pressure A/F mix is too hard to start burning. Here is a GREAT read for anyone that wants to really understand the combustion process. It is written by a "Northstar" GM engineer. It's very easy to read and understand, and you'll start to see why the whole engine package is very important to understand. http://www.3si.org/forum/showthread.php?t=281822

 

[norbs]

What happened was #4 cyl the spark plug broke and the tip burned off sending the insulator in to the piston, destroying it and the valve and the turbo exhaust wheel. This was on 28 psi on ultra 94 with 22 degrees timing and 11.1-2 a.f ratio. Estimated percentages of alky are near 40% of fuel volume. There was no knock , not even .1 degree at all!

 

[pacecarta]

40% seems like an awful lot of meth

at 24psi i was running at 69-72% of my 75's at 55-5600 rpm on gas , with alky im now at 58-60 % and have started bringing up timing (24/22) with no additional alky and no knock no knock retard
10.7 124 , 6.8 99 so far and on another pass it went 101.5
still tuning and pulling alky out little by little at the same time bringing in a little more 93

 

[turbofabricator]

Only 22* timing may be a little too retarded for that much methanol, causing pre-ignition. Read the above link. Peak cylinder pressure target is 14*ATDC. I know we can't measure this, but it is a number to remember. Keep it in mind when you are setting your tune-up. Late ignition timing can burn up more stuff than you think. It'll melt exhaust valves. I've seen it kill a set of inconel exhaust valves Keep a close eye on EGT at low timing settings and be sure to verify your timing setting mechanically, in that it may read 22* on the 'puter, but the interuptor ring on the balancer is not phased correctly. If you are trying for a kill tune-up you need to verify the timing the old fashion way. with a good timing light and a degreed-in indicator. Geno just had a customers car, that has ran poorly since he bought it a couple of years ago, and he found an elongated keyway on the balancer. Just another thing to keep in mind, too.

 

[Reginald West]

When I strated this thread I was looking for an octane rating for methnol but along the way you guys have given me a good education on using this stuff for that I say Thank You to all .

Norbs you said your fuel mix was 40 % methnol 60% Gas I would be interested knowing how you determined what the percentage of methnol was.
And are you using more than one jet to spray methnol into the system?

REG

 

[norbs]

yesi am using two nozzles. I did some rough calculations from a m10 jet and a m15 jet @150 psi average. Also took some fuel flow numbers from the dfi. On the single nozzle i was getting knock still. Thanks, turbo fab for your suggestions, i may haveto put more timing in as you suggested. I have a crank trigger and distributor in and the timing is right on now.

 

[Razor]

I run on my everyday tuneup 23.5 degree's.. and when I get frisky I bump it up to 24.5-25 degree's.. and it picks up... but waiting for some better weather to get frisky with the tuneup.

My car doesnt like any AFR close to 12.0.. At 11.0-11.2 I can throw anything at the timing settings.. so make sure your tuneup isnt swinging lean then rich.. becuase when it swings lean.. bad things can happen.

Ditto on EGT

HTH

 

[Razor]

Julio,
How about if you are sitting on the 2-step on the line for a few seconds? Thats similiar to bouncing off the rev-limiter? I suppose then you should have the wire grounded to reduce flow, or it really isn't a problem?

Troy

When I sit on the two step its at lower boost.. so the load on the engine and alky flowing are both low. Way different than running 30 PSI and bouncing off the limiter.

Now playing with the nitrous for spooling.. this using the two step is freaking me out whether to do it or not :redface:

So do you bounce of the two step as nitrous/methanol is entering the motor????..

 

[pacecarta]

razor ,i was going to bring this question up to you about the launch but since you're on the subject

i now use the msbc-1 boost controller for two step (launch) , its not a two step like my MSD so no bouncing and sputtering just a clean smooth whoosh as i hold foot to floor at my launch boost on the t brake, just before going alky i could 60' 1.4s leaving at 12psi . now with alky on (gain at 11:00) if i try to launch at anything above the 6 psi turnon it drowns the motor out (twin nozzle setup) and i have to wait for car to build again only to have it get drowned again ,

so right now i'm limited to 5 psi hit and on 28" slicks i cant manage more than a 1.68 , at the same boost i could do 1.5s on the 26' 255/55-16s
any advice ,its either work out the launch since i need a bigger hit on the slicks or get another set of mickey radials ,the last set started showing some cord last week but were still launching good. i was thinking of trying the mystery wire and grounding it on another switch at the shifter

this new dual setup will knock the motor right down with just touching the test button at idle , my single nozzle setup on the 87 i could hold the test forever and unless i turn gain knob to full it isnt noticible that its spraying so i have no issues building boost above 6psi and having the alky spraying even though i dont normally build much boost on the brake on that car

btw i'm at 25mph 1/8 to 1/4 pickup now at 24psi (just at 125) with only my 60's keeping me from some mid 10s ,

 

[Pablo]

Why dont you reduce the initial knob setting?

 

[Pablo]

By the way

as far as methanol pre-igniting

what is the dominant factor there? Hot exhaust valve from retarded timing?

In the same vein, from what I understand, advanced timing also puts alot of heat into the chamber/piston crown. I say this because of what I have observed from tuning my cruise areas. Lower timing on the highway gives better oil temps.

Does the cruise stuff not apply because you arent detonation limited with your timing?
Im guessing the timing upper limit at WOT is dictated by detonation, and at part throttle its not (as often/much) ?

 

[norbs]

WHen i had my failure, my egt's were about 1620. So word to the wise, dont push the limits of pump gas and methanol mixed, as you will find out the hard way. I would say 25 psi is about the safety limit.


Cyl temp is higheest at Stoich, adding timing at cruise lowers egt, and cyl temps. Not sure how you oil is getting hotter, please explain

 

[Pablo]

WHen i had my failure, my egt's were about 1620. So word to the wise, dont push the limits of pump gas and methanol mixed, as you will find out the hard way. I would say 25 psi is about the safety limit.


Cyl temp is higheest at Stoich, adding timing at cruise lowers egt, and cyl temps. Not sure how you oil is getting hotter, please explain

Cyl temp highest at stoich, yes, adding timing at cruise lowering egt yes... but...

The part about adding timing at cruise lowering cyl temps is incorrect, Bruce Plecan is probably the best guy to explain this since he has hard data to back it up. But basically as I understand it, when you advance the timing, all of your heat energy is being imparted on the chamber. When the timing is retarded, alot of that heat energy is going out of the exhaust, not the chamber. Thus you have higher chamber temps which translate to hotter oil temps and lower oil pressure. Im sure theres a lower extreme too that raises cyl temps aswell but from what I understand, even stock timing tables are pushing the limits as far as part throttle timing and the heat it imparts on the chamber. Clearly that must be for emissions purposes.

If you do a search on bruce plecans posts youll see him go into detail about this and its effect on knock when you get back on the throttle after say a highway cruise. I took his advice and reduced my highway timing and made a vast improvement on my temps and tendency toward knock at WOT after an extended cruise.

as for your suggestion for PSI, Im not sure you can just make a hard and fast rule like that. It would seem to me like there are too many variables involved for example from turbo to turbo, and engine dynamic C/R.

I know for a fact alot of guys (myself included) are running more than 25 psi on methanol. I have been running between 26 and 28 psi for some time and havent blown it up. Maybe I have been lucky, or maybe my dynamic CR isnt that high what with my stock heads and cam.

DonWG what psi do you run running pure methanol?

 

[turbofabricator]

Another thing to remember about boost is that boost pressure is a measurement of RESTRICTION. If you were to hook your turbo at WOT to, say a hot air baloon, it wouldn't make ANY boost (at least not for a week or two ) If you have a good set of heads and a matched camshaft, then the car will make more power at a lower boost setting. There is sooooo much that determines how much boost your combination can handle on your tune-up. 25 psi boost on a NHRA prostock engine would KILL it even on straight methanol. We have a set of heads (8445 castings) that really do work well with some talented porting, but they are 40+ year old technology. Combustion chamber mods, good valve seat prep, correct valve to guide clearance, NO oil in the combustion chamber, (i.e good rings and valve seals) ALL plays a role in what an engine can handle as far as boost is concerned. I know this is old info, but I think that everyone needs to keep the whole package in mind when they start to wring out as much power as they can from these little V6's. Just because "John Doe" has the same parts on his car, doesn't mean your car will run the same! It takes many, many, hours and TONS of thought to safely persue your horsepower goals. Go slow, or you might just drive over the crankshaft

 

[Alky V6]

DonWG what psi do you run running pure methanol?

I'm not an expert at burning methanol so don't take the following examples as the limit of what can be done with it.

First engine: 10.45 to one CR. Insufficient fueling. Blew at 31 psi.
Second engine: 11.27 to one CR, mixture read 11.4 on the O2 (calibrated to read out gas numbers) This mixture gave best power. Not necessarily best safe power. Blew at 28 psi.

Can you figure out what the dynamic CR was for the second engine?

Third engine: 9.27 to one CR. Target mixture 13.4 at idle, 11.7 to 12.2 before boost, 11.0 to 11.3 under boost. Target max boost 28 to 30 psi. Preliminary fueling requirements of this engine are down 9% on the injector pulse width from the last engine. This is in the non-boosted regions of the fuel map. This goes to show you that methanol likes compression.