Motorsports Village

My E85 1150
Page 5 of 7

Author:  jmarkaudio [ Wed Jan 12, 2011 7:59 pm ]
Post subject:  Re: My E85 1150

I do have a 4150 style RS with removable boosters and two sets of sleeves 825 with 1.425 venturi and and 970 with 1.500, might be easy enough to replace them with tubes... :-k :-k :-k

Author:  shrinker [ Wed Jan 12, 2011 9:44 pm ]
Post subject:  Re: My E85 1150

You wont get enough signal without the booster.Ive been there and done that and what I make is a lot more than a tube. There is nothing in common with my carby and a Holley other than some spare parts.

Author:  jmarkaudio [ Fri Jan 21, 2011 12:26 am ]
Post subject:  Re: My E85 1150

Why won't it work? C&S manages to make their tube discharge work, although I don't imagine atomization is good at lower RPM. I know in talking to them they use no emulsion and a small kill bleed. They do rework the venturi, a sleeve similar to an RS Demon, but taller and the venturi raised higher. I would not want an open tube either. And not for street use, only running in a drag car.

Well as a side note, I installed the Racepak today. I did not get time to drill the manifold for the vacuum sensor, I'll do that later. O2's are the most important for the moment, 11PM when I finished so I could not start it. Set up the software, free air calibrated the O2's, did a dry record. Good to go for Saturday if the weather is good.

Author:  shrinker [ Fri Jan 21, 2011 12:46 am ]
Post subject:  Re: My E85 1150

A booster does not inhibit the flow rate of the main venturi. A booster does exactly what it says, It boosts the vacuum to a level that is higher than the main venturi without a restriction in it. Tricky huh. The outlet of the booster is level with the minimum restriction of the main venturi. Thats how you create a boosted vacuum level in the circuits of the carby without requiring a larger venturi to flow the max power and suffering the lack of signal at low CFM flow rates. If you put a booster on top of a booster you just keep repeating the design principles up the stacked up boosters. BUT importantly you dont restrict the flow of the main venturi. SO what you get is a high enough vacuum at the main jet so that its liquid flow coefficient can match the flow curve of the air on that page of Larew's book If you dont get it right then you need to fix it with emulsion.

if you put a tube across a venturi as has been done many times on stock carbys on Japanese cars etc then you cant amplify the vacuum for the same size venturi area. you loose venturi area and get the signal that way. You need a much larger area to flow the same CFM on a non amplified design compared to a booster design. To solve that issue with the Japanese cars they fitted tubes across boosters, then they still had to fix it with emulsion so whats the point. Nothing.

A booster is an amplification not a restriction.

Author:  shrinker [ Fri Jan 21, 2011 8:11 am ]
Post subject:  Re: My E85 1150

The air flow that goes down a venturi is basically fixed for the area for all venturis. Provided you dont have stupid entry and exit angles then one guys venturi is going to flow the same as another. There are no secrets in venturi design despite what some gurus claim.
So if you have a given venturi hole area your going to get a certain CFM for a certain vacuum. If you need the main circuit to come on at say 10hp per barrel then you need to generate some vacuum to lift the fuel to the point of discharge of the main circuit. You can either use a booster venturi to create the vacuum necessary to get it working at 10hp or you could use a single point design like the C&S etc. What the C&S style design uses is the area of the main venturi to generate the vac you need. To get the vacuum you have to reduce the area of the venturi compared to a booster design in order to lift the fuel at the same 10hp point. You can get rid of the emulsion bleeds and that doesn't waste as much vacuum so you can get the fuel up to the height without making the area smaller etc so to some extent that helps. BUT you then dont have emulsion to do corrections and stuff like that so the tuning of the carby becomes very temper-mental and the carby is set up for one individuals engine Its not a mass production option. The C&S is a methanol design principally and its the rang-ability of methanol that enables that design to work acceptably. But it then has to be considered with the engine thats underneath it. Some engine combination's probably wouldn't like that design carby because the combo might be fussy about fueling accuracy.
If you use a booster venturi then you can have a larger main venturi than if you use a single stage design like the C&S. The problem with using a booster is that you will need emulsion in order to tune it as a mass production carby.
You get problems of fuel clogging up the booster, you get more intense changes to the vacuum curve. So you have to have a system to deal with that and thats what the air bleeds do. But an air bleed carby is heavily influenced by fuel level in the well and flow rate through the main jet. So all the little things matter.

Author:  jmarkaudio [ Fri Jan 21, 2011 1:27 pm ]
Post subject:  Re: My E85 1150

I guess that is my point about trying it with ethanol, It's a little forgiving like methanol and the viscosity difference might like not having to deal with emulsion. Of course if you could figure a way to run the fuel level at the level of the nozzle/spray bar or slightly above without spillover, then it would not have an issue pulling the fuel in. Now how to stop spillover/siphoning...

Author:  shrinker [ Fri Jan 21, 2011 4:36 pm ]
Post subject:  Re: My E85 1150

You stop all fuel control issues like spillover, siphoning, g-force influences by placing the bowl underneath the barrel in a side draft configuration. Look at any motorcycle carby and your looking at the best.
Combine all the right features for a mass production carby and you finish up with a Weber.

Yes ethanol would be much more suitable to do the C&S thing than methanol is. But E85 is not Ethanol. When you solution Ethanol with gasoline you dont get a simple ratio change in the viscosity. Somewhere in the dark places of my mind is recorded that you actually get higher viscosity at certain percentages of mix. The expected viscosity is not always achieved, it depends upon the Gasoline type and the mix ratios. Im not sure but I think its in the region of E15. I'm not sure if research has actually been done on E85 and its variances with different gasoline chemical blends over summer winter etc. I am sure it makes a difference what gasoline HC's you mix it with as to how it reacts with viscosity.

If your just chasing E blend fuels for racing flat out then its a valid worthwhile exercise but if you expect to get perfect results on the street with all the legalities necessary then its a lost cause. Straight Ethanol is good and with less problems.
I cant see that a carburetor could equal or better a good design EFI with E blend fuels, whereas good carburetion is better than good EFI on gasoline's. The issues are with the control necessary to correct the variances of the blends. EFI is easier to do that.

Author:  jmarkaudio [ Sun Jan 23, 2011 3:47 pm ]
Post subject:  Re: My E85 1150

@$$&^*&)(!!!! ](*,) ](*,) ](*,) ](*,) ](*,)

OK, better. Made runs last night, everything on the RP worked EXCEPT.... yep the O2's. Free air calibrated, the software showed all was well when I set it up. Getting reeeeally frustrating. Here is a screenshot of the first pass.

Author:  mslayton [ Sun Jan 23, 2011 9:40 pm ]
Post subject:  Re: My E85 1150

Bummer Mark. Sorry to hear your string of bad luck continued. I'm sure you'll get it sorted out soon.

Author:  jmarkaudio [ Wed Feb 02, 2011 10:07 am ]
Post subject:  Re: My E85 1150

O2's are now working, no time to run it yet. I will try to log it later today in the trailer against the t-brake to see how close, going to try to run Saturday.

Author:  jmarkaudio [ Wed Feb 02, 2011 11:21 am ]
Post subject:  Re: My E85 1150

Looks like I have work to do.In the trailer, no rev limiter on, against the converter, about 6400 RPM. Coan converter I had reworked for the SB2, had them put in a sprag and tighten up. I can imagine what it will be with the SB2... #-o


Author:  mslayton [ Wed Feb 02, 2011 11:47 am ]
Post subject:  Re: My E85 1150

Glad you got everything working. It will be interesting to see a full pass vs just up against the converter. I'm wondering if the lack of good airflow to the carb in the trailer causes things to get leaner than if going down track. Good luck this weekend, I'm assuming your have some larger jets this week.

What did you need to fix to get the o2's working? Electrical interference issue?

Author:  jmarkaudio [ Wed Feb 02, 2011 1:08 pm ]
Post subject:  Re: My E85 1150

Software reflash, had to get Racepak on the phone. Not sure what fixed it, did several things. The carb is off, adding .059 holes between the slots. Two between two spots, three at the booster exit. I will probably plug the bottom of the two open ebleeds, leave only one in the second position. If that does not bring it down I can do some jet drilling, I have some alky Demon blocks I can get larger jets for to try as well if I don't get much response.

Author:  jmarkaudio [ Wed Feb 02, 2011 4:46 pm ]
Post subject:  Re: My E85 1150

OK, after removing the inserts, adding holes, plugging the lower open bleed it seems to be the same. Also added a vacuum port to my spacer, so the vacuum sensor is working, .5" WOT. Going to make a trip to BLP tomorrow, get some larger jets. They have up to .177's for gas blocks, if it needs more I may need to make a metering block change. Here is the latest screen.


Booster mod


Tools to R&R


Author:  mslayton [ Wed Feb 02, 2011 8:46 pm ]
Post subject:  Re: My E85 1150

Wow, it's hard to believe that your lean with that much done to the booster.

In different website posts Mark and Eric each seem to be both seem to have their dominator jetted in the 104-106 range which shouldn't translate to even the size jets your running now. This has got me really wondering what they've done with their tune-up considering they both use modified holley metering blocks.

Page 5 of 7 All times are UTC - 5 hours
Powered by phpBB® Forum Software © phpBB Group