Login    Forum    Search    FAQ

Board index » Racing Forum » Fuel Systems




Post new topic Reply to topic  [ 21 posts ]  Go to page 1, 2  Next
Author Message
 Post subject: Barrel Ratio
 Post Posted: Wed Nov 09, 2011 2:20 pm 
Offline

Joined: Thu Feb 12, 2009 7:52 pm
Posts: 348
Hello All,

Well I got to urge to tinker with my dominator some more and I decided to change the barrel ratio to a 1:1 from the progressive setup.

I am looking for pros and cons of setting it up this way.

From a tuning standpoint, I would think this would simpfied tuning a bit because I would think that the front and rear bleeds and jets would be pretty much be the same. Then from an engine standpoint, the fuel mixture would be more consistant through out the engine being able to draw the 4 barrels all the time vs two barrels when at launch and cruise rpms.

I also went in and corrected the metering block offset issue. Below is a link to where I discussed the issue. I figured out which crosswell was open the most, then match the rest of them to that size. I then squared up the jets and based on my load testing, it seems to have worked because all the egts are very close.

viewtopic.php?f=6&t=8379

Also I found it interesting, the carb seems to have riched up .5 on the afr scale at wot. I want to run it first before I make any jet adjustments. Definitely seems to have richen up at the cruise and launch rpm. It looks like the mains are coming in at 2000 rpms, I actually expected it to be later as a result of the load being put accross all four barrels vs two.

Which brings me to another question, Off the footbrake, what would be the better launch afr, The WOT max power AFR, or would it be better leaned up a bit to get it to WOT Cleaner?

Engine seems very responsive right now, we will see how she runs this weekend.

_________________
74 Nova
Best 9.87@131 on the rev limitor 1 Feb 2013
1/8   6.15@110 NEW BEST 27 Nov 11
Image


Top 
 Profile  
 
 Post subject: Re: Barrel Ratio
 Post Posted: Wed Nov 09, 2011 3:09 pm 
Offline
Site Admin
User avatar

Joined: Tue Apr 18, 2006 6:38 am
Posts: 11804
Location: Coming At Ya!
I've been running my "original" 1150 Methanol Dominator at 1:1 since I first put it on my engine 5 years ago and the "new to me" 1150 methanol Dominator I'm in the process of building with my "home made" external (see pic) linkage will also be 1:1 but then again, I'm coming off the transbrake at WFO to begin with so it really doesn't matter other than there's time for the pump shot to be burnt up earlier in the run.

Image

I can see that there will be a "learning curve" with a footbrake car though with that 1:1 ratio because it will hit the tire a little harder quicker into the run, which will make the car leave quicker and also yield more "red lights" until you get use to it. So plan a few test and tune sessions to get that part right before you go racing with it! I'll bet the short times will be better also because the secondary pump shot will be burnt up quicker. \:D/

_________________
Big Boyz Toyz!

Image

Necessity is the plea for every infringement of human freedom. It is the argument of tyrants; it is the creed of slaves.

William Pitt, British Prime-Minister (1759-1806)


Top 
 Profile  
 
 Post subject: Re: Barrel Ratio
 Post Posted: Wed Nov 09, 2011 6:07 pm 
Offline

Joined: Thu Feb 12, 2009 7:52 pm
Posts: 348
That would be benficial for me if it responds faster. But looking for a tunable way to adjust my RT.

Got to ask, whats up with the wire to the boosters?

_________________
74 Nova
Best 9.87@131 on the rev limitor 1 Feb 2013
1/8   6.15@110 NEW BEST 27 Nov 11
Image


Top 
 Profile  
 
 Post subject: Re: Barrel Ratio
 Post Posted: Wed Nov 09, 2011 7:42 pm 
Offline
Site Admin
User avatar

Joined: Tue Apr 18, 2006 6:38 am
Posts: 11804
Location: Coming At Ya!
During a Whelen Modified race in Martinsville, Va in 1985, Richie Evans, who had clinched the 1985 title and won more Modified titles than anyone in history died as a result of a carburetor malfunction. What happened was that a booster in a 4150 Holley carburetor came loose, fell and hung up in the butterfly and then caused the throttle NOT to close when he went into the corner. He died of a basilar skull fracture (Dale Earnhardt too) when his car hit the wall with the throttle stuck near wide open.

These Dominator boosters have a booster pin that holds it in place. They also have a leg on the other side that helps keep them from going down the venturi. These boosters are held in by a single 10x32 allen head cap screw only, so THAT is the reason for the safety wire. ;-) FYI, you will not find a 4150 carburetor ANYWHERE in NASCAR that DOES NOT have the boosters safety wired to the main body. I'm old, fat and ugly but I'm not stupid! We learn from others mistakes......sometimes! ;-)

_________________
Big Boyz Toyz!

Image

Necessity is the plea for every infringement of human freedom. It is the argument of tyrants; it is the creed of slaves.

William Pitt, British Prime-Minister (1759-1806)


Top 
 Profile  
 
 Post subject: Re: Barrel Ratio
 Post Posted: Wed Nov 09, 2011 8:28 pm 
Offline

Joined: Thu Feb 12, 2009 7:52 pm
Posts: 348
Very interesting, I never would have thought of that. So is that your work on the car, removing that leg that supports the booster? I assume to give it a little more flow huh.

_________________
74 Nova
Best 9.87@131 on the rev limitor 1 Feb 2013
1/8   6.15@110 NEW BEST 27 Nov 11
Image


Top 
 Profile  
 
 Post subject: Re: Barrel Ratio
 Post Posted: Wed Nov 09, 2011 8:50 pm 
Offline
Site Admin
User avatar

Joined: Tue Apr 18, 2006 6:38 am
Posts: 11804
Location: Coming At Ya!
fourtenposi wrote:
Very interesting, I never would have thought of that. So is that your work on the car, removing that leg that supports the booster? I assume to give it a little more flow huh.


Bill I basically did that just to prove to myself that it would work.......or not. You know, like you do all the time, ie, never satisfied and want to always be trying other stuff to see if there is something better. Without that other "leg" there's less restriction in the venturi that "may" increase flow but my primary reason was to see if this did anything different as far as fuel distribution is concerned. There's other stuff that is being done in the metering system, etc that I'll give more details on once I get it on the engine to see how it goes. This thing is one of those "outside the box" type deals and is a culmination of a bunch of different things I've been thinking of since way back when I was on speaking terms with Maley.

_________________
Big Boyz Toyz!

Image

Necessity is the plea for every infringement of human freedom. It is the argument of tyrants; it is the creed of slaves.

William Pitt, British Prime-Minister (1759-1806)


Top 
 Profile  
 
 Post subject: Re: Barrel Ratio
 Post Posted: Wed Nov 09, 2011 9:08 pm 
Offline

Joined: Thu Feb 12, 2009 7:52 pm
Posts: 348
Nothing wrong with that, I am curious to see how it works out for you.

So any opinions out there for the ideal fuel mixture at launch rpm in a footbrake car? Would it be better to have your final mixture the same as going down the track, or would it be better to have it leaner so it would be cleaner?

_________________
74 Nova
Best 9.87@131 on the rev limitor 1 Feb 2013
1/8   6.15@110 NEW BEST 27 Nov 11
Image


Top 
 Profile  
 
 Post subject: Re: Barrel Ratio
 Post Posted: Wed Nov 09, 2011 10:02 pm 
Offline
User avatar

Joined: Sat Feb 07, 2009 4:12 pm
Posts: 1215
Location: Adelaide Australia
It has been proven in scientific tests that isolate all other factors that whatever AFR is the maximum power at any point in the rev range is the same AFR required for maximum power at any measured point across the entire rev range at any load percentage.
In practice thats very rarely the case and the reason is because our engines dont utilize the fuel correctly and the efficiency of the utilization varies with RPM. However under conditions of perfect vaporization my opening statement is correct.
Any deviation in AFR that results in more power is because of other factors corrupting the combustion of the engine.
Due to the variety of combination's in use it is not possible to accurately predict an AFR to answer you.


Top 
 Profile  
 
 Post subject: Re: Barrel Ratio
 Post Posted: Mon Nov 14, 2011 1:24 pm 
Offline

Joined: Sun Sep 02, 2007 9:07 pm
Posts: 49
Location: kewanee,il
fourtenposi wrote:
Hello All,

Well I got to urge to tinker with my dominator some more and I decided to change the barrel ratio to a 1:1 from the progressive setup.

I am looking for pros and cons of setting it up this way.

From a tuning standpoint, I would think this would simpfied tuning a bit because I would think that the front and rear bleeds and jets would be pretty much be the same. Then from an engine standpoint, the fuel mixture would be more consistant through out the engine being able to draw the 4 barrels all the time vs two barrels when at launch and cruise rpms.

I also went in and corrected the metering block offset issue. Below is a link to where I discussed the issue. I figured out which crosswell was open the most, then match the rest of them to that size. I then squared up the jets and based on my load testing, it seems to have worked because all the egts are very close.

viewtopic.php?f=6&t=8379

Also I found it interesting, the carb seems to have riched up .5 on the afr scale at wot. I want to run it first before I make any jet adjustments. Definitely seems to have richen up at the cruise and launch rpm. It looks like the mains are coming in at 2000 rpms, I actually expected it to be later as a result of the load being put accross all four barrels vs two.

Which brings me to another question, Off the footbrake, what would be the better launch afr, The WOT max power AFR, or would it be better leaned up a bit to get it to WOT Cleaner?

Engine seems very responsive right now, we will see how she runs this weekend.



GOOD OLE BILL...............ALWAYS LOOKING FOR AN ANGLE =D> ...........ME TOO. ......hope the 1:1 deal proves out as a positive for you......keep us up to date.

_________________
thanks jerome baker
proud owner of, RFD 18 DEGREE MONSTERS


Top 
 Profile  
 
 Post subject: Re: Barrel Ratio
 Post Posted: Mon Nov 14, 2011 1:43 pm 
Offline

Joined: Thu Feb 12, 2009 7:52 pm
Posts: 348
I didn't run it this weekend, I had to work on saturday, so sunday was just a race day, and I didn't feeling like messing with it, so I ran old faithful. Decided to double enter and do a little electronics racing. Got down to six cars in no-e and got a little more seat time in electronics. ](*,)

But I must say, I really like leaving off the transbrake.

_________________
74 Nova
Best 9.87@131 on the rev limitor 1 Feb 2013
1/8   6.15@110 NEW BEST 27 Nov 11
Image


Top 
 Profile  
 
 Post subject: Re: Barrel Ratio
 Post Posted: Mon Nov 14, 2011 2:47 pm 
Offline
Site Admin
User avatar

Joined: Tue Apr 18, 2006 6:38 am
Posts: 11804
Location: Coming At Ya!
fourtenposi wrote:
But I must say, I really like leaving off the transbrake.


Ah yes, another top bulb racer in the making! If you like it, then you're already hooked! ;-)

_________________
Big Boyz Toyz!

Image

Necessity is the plea for every infringement of human freedom. It is the argument of tyrants; it is the creed of slaves.

William Pitt, British Prime-Minister (1759-1806)


Top 
 Profile  
 
 Post subject: Re: Barrel Ratio
 Post Posted: Mon Nov 14, 2011 6:52 pm 
Offline

Joined: Thu Feb 12, 2009 7:52 pm
Posts: 348
I have been dabbling in it here and there for a while now. My first love is footbrake, but I like to run both when the tracks will allow it. I would just like to do it more often. It pulls the wheels a bit more to and that is always fun.

I find it interesting, my car generates more starting line g-force off the footbrake vs the t-brake, but the t-brake is faster only by .02 in the sixty. The car actually feels smoother off the t-brake, but that may be because of have the adjuster in the reid case full soft.

_________________
74 Nova
Best 9.87@131 on the rev limitor 1 Feb 2013
1/8   6.15@110 NEW BEST 27 Nov 11
Image


Top 
 Profile  
 
 Post subject: Re: Barrel Ratio
 Post Posted: Mon Nov 14, 2011 7:45 pm 
Offline
User avatar

Joined: Wed Apr 19, 2006 8:20 pm
Posts: 5852
Location: N.J.
Bill, What rpm are you leaving at with the TB??
TB should be a lot faster but you may be wasting time going up instead of forward =;

_________________
Image
running E85
Best ET 8.07
Best MPH 170.71
Barry


Top 
 Profile  
 
 Post subject: Re: Barrel Ratio
 Post Posted: Mon Nov 14, 2011 7:59 pm 
Offline

Joined: Thu Feb 12, 2009 7:52 pm
Posts: 348
I come off the t-brake at 4200, I tried higher, but it didn't go any faster, It was consistent there. How much et differance would you expect, I see about .06 difference.

Like I stated before, that case adjustment may have something to do with it.

_________________
74 Nova
Best 9.87@131 on the rev limitor 1 Feb 2013
1/8   6.15@110 NEW BEST 27 Nov 11
Image


Top 
 Profile  
 
 Post subject: Re: Barrel Ratio
 Post Posted: Mon Nov 14, 2011 8:24 pm 
Offline
User avatar

Joined: Sat Feb 07, 2009 4:12 pm
Posts: 1215
Location: Adelaide Australia
When you footbrake the diff torque reaction is planting the tires before you start moving.


Top 
 Profile  
 
Display posts from previous:  Sort by  
 
Post new topic Reply to topic  [ 21 posts ]  Go to page 1, 2  Next

Board index » Racing Forum » Fuel Systems


Who is online

Users browsing this forum: No registered users and 4 guests

 
 

 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: