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methanol A/F ratio on race engine

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methanol A/F ratio on race engine

Postby seefour » Sun Jun 17, 2007 1:50 pm

i have a brand new engine combination that was built similar to a engine on CHI"s web site but its alcohol injected there motor made 785 hp with a meth dominator.

I went to the chassis dyno yesterday and about died
my combo is 410 inches , chi 3v heads 218 cc runners 338-238 cfm
775 -757 lift 266-274 @.050 108 sep 14.0 compression 240 lbs cranking compression 4.0 stroke 6.0 rod vacume pump ect.......


first pull 24 degrees timming base line nosed over 5900
second pull 26 timming , gained 30 ft tq nosed over 5750
third pull 28 lost nosed over 5750
pulls made from 50 mph to 110 mph average time 1.5 seconds

egt was 1005 to 1070 max

a/f ratio 3.8 idle 4.83 durning run highest, water temp never climed and
CHI's motor ran best at 5.3 to 5.8 a/f

I guess what Im getting at my jets are #37 with 0 1/2 pump
I tried at 94 return pill base line and tried #90 and motor lost power
'so it didnt like anymore fuel at all

with the a/f ratio off that much and motor nosing over at 5750 rpm is it way fat?

the dyno operator said it would be 25% loss from flywheel to rear wheel hp with puts it at 622 hp at 5750 rpm. but dies from there.
the motor would physically turn to 6800-7000 but made less power from 5750?

made 7 pulls and water temp never got off 140

egts were 1007 to 1070


I need some help please

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Postby bill jones » Sun Jun 17, 2007 2:44 pm

-Here is a quote from Dave Dahlgren regarding an Enderle hat style injection on top of a tunnel ram.
---------------------------------------------------------------
-While it has been a while since doing mechanical injection here is the way I did it on the dyno to baseline the system.

-First plug the secondary bypass (means hi speed relief), the one with a spring loaded check valve and another pill.

-Install a pressure gauge on the pump output that you can either see or data log along with rpm.

-Run the engine adjusting the main bypass for best peak torque this will be too rich at peak Hp.

-Also record the local weather readings as you work.
-Local meaning at the engine not the parking lot as the temps can be wildly different.

-With the main set correctly go back and see what rpm you have peak torque and what pump pressure is at peak torque.
-Set the secondary bypass spring (high speed relief) pressure with a leakdown tester pressure/regulator to just barely hiss at the pump pressure for peak torque.

-Install a very small pill in the secondary bypass (hi speed relief) and use the dyno sheet to get a good idea how big it might be by how fast the torque is falling off. Make this pill larger until you hit peak HP.

-This sounds like a long drawn out thing but actually happens pretty quick.

-When done at the track change the square inch area of the main bypass to correct for weather.

-A 10% change in density altitude needs a 10% change in area.

-Another good rule of thumb is if you are running a blower and you double the manifold pressure you need to double the fuel by cutting the main bypass square inch area in half not the diameter.

-As a side note a belt drive pump and a chart to go with the pump rpm vs. pressure is a very valuable tool as it allows you to change the drive ratio to make big changes and still stay within some reasonable selection of nozzle and jet sizes.

-Also I use a leakdown tester once the barrel valve is set for the best compromise of idle quality and response. That way you can get back to that point quickly if the system is taken apart for service.
-------------------------------------------------------------------------------
-My personal experience with stack injections has always been that a hi-speed relief is needed at around peak torque---where the hi-speed relief dumps off all that excess fuel that the engine can't use.

-You need the normal main bypass and the high speed bypass if you are trying to run the engine over peak torque.

-If you look at your fuel pressure curve---you'll see that the fuel pressure continues to increase above peak torque---and you need to limit the fuel pressure with the extra hi-speed relief---which is a juggling act between the poppet spring pressure---and the pill (jet) you choose.
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Postby Wolfplace » Sun Jun 17, 2007 6:23 pm

Great post Bill, thank you for sharing :notworthy:
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Postby RW TECH » Sun Jun 17, 2007 9:56 pm

I took a similar tuning approach with a Hilborn stack setup on gas and it worked awesome. In my case, I targeted 55-60 psi fuel pressure at peak torque, then worked the high speed until I went a tad too far then went back to best HP from there.

Setup was on a great big garbage truck Hemi motor and it ran within .06 ET over a 10 week period during the spring/summer transition.
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Postby Brian B » Mon Jun 18, 2007 8:28 am

Two things I would look at before I even think of HP..

Fuel pressure is good and correct for the nozzles your running..

system plumb correctly and where your return line goes...

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Rons fuel says....................?

Postby seefour » Mon Jun 18, 2007 5:02 pm

i contacted a couple of different people today at Rons Fuel, they assured me that the nozzels(jets I am running are way to large and need to drop down a couple of sizes.
also told me that during a pass the A?F ratio need to be 5.8-6.0 in that range wich I wasnt even close. I picked the wrong nozzels size thinking the motor would need that much, I was wrong.


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Re: Rons fuel says....................?

Postby Eric David Bru » Mon Jun 18, 2007 7:33 pm

seefour wrote:...also told me that during a pass the A?F ratio need to be 5.8-6.0 in that range wich I wasnt even close.

Mike S


Seems pretty lean to me... :shock:
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please explain why

Postby seefour » Mon Jun 18, 2007 8:16 pm

Why do you say really lean?


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Postby TOP38 » Mon Jun 18, 2007 9:09 pm

Mike

Call James Monroe at 812-327-1190
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okay, I did have e-mail with him yesterday

Postby seefour » Mon Jun 18, 2007 9:19 pm

I sent him a few e-mails Sunday night wich he replied to today, He is the one how told me #35 pills instead of the # 37 and that the a/f ratio should be 6.0 at the high end


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Postby Eric David Bru » Mon Jun 18, 2007 10:01 pm

I was always told:

4.5:1 for leaving the start line.
5.0:1 for peak torque.
5.4:1 for peak HP.

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Postby Ed-vancedEngines » Mon Jun 18, 2007 10:59 pm

Sir;
I appreciate you seeking me to send a PM about this subject but to tell the truth, you probably already know more than I do on this subject. I know very little if anything at all.

Sorry I could not respond with help.

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Postby Hendrens Racing Engines » Tue Jun 19, 2007 8:15 am

The 5.8-6.0 is where our alky engines make the best power.alky engines require 2.2 times the amount of fuel as a gas engine.Bill
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Postby Brian B » Tue Jun 19, 2007 8:38 am

seefour

I highly recommend pulling the pan and checking
upper half of rod bearing.....

When I had my engine shop I had a customer that
thought he new how to "jet" his sprint car..
Well about 5 laps in on a 1/2 mile track and the car
was hooked up...blew the bottom end out on to
the track...all good parts..

When I tore what was left of the motor down all of
the upper half of the rod bearing were all crushed..
@8000 rpm on a 1/2 mile track and over fuel it
hydraulic under a load....
And yes some of the rods were bent!!

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Y4ES I WAS OFF BUT NOT ENOUGH TO HYDRALIC THE MOTOR.

Postby seefour » Tue Jun 19, 2007 4:54 pm

I HAD SEVEN PULLS TO 6500 RPM THIRD GEAR ONLY , THANKS FOR THAT ADVICE , IF IT COMES APART I WILL SAY I TOLD THAT YOU TOLD ME SO.


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