Hi Guys
Dont know if this is the right place but maybe some one can help me out with some info or direct me to some where else. I want to run quad throttle bodies on a sohc 2ltr (one throat per cylinder) currently I have twin 45mm dellorto's and for an all out race motor 48s are recommended most stock efi 4 cylinders run one throttle body. I will be using the throttle bodies with a mechanical alky injection system. So the question is what size butterflys in the throttle bodies do I need? I was thinking 45mm or 48mm but I spoke to a guy and he said injection is not like carbies in that the airspeed in the carb is critical for propper fuel atomisation and because in throttle bodies the fuel is being injected in a mist you can run bigger throats and still retain good atomisation. So maybe 50mm maybe the go there maybe a formula to work this out but I dont know of one. If you have had any experience in this area your thoughts will be much appreciated.
You mean a set up like this?
you must be able to read my mind that looks just right I will probably be making mine and it may not look as nice but as long as it works!
What size are they? and what do they suit? what size motor?
Were they used for methanol ?
Thanks.
This unit fits a Pinto 2.0L. The bore on the throttle is about 2". This is a Mechanical Hilborn unit that will handle Methanol or gas depending on the Pill you use. You can get this at Esslinger Engineering.
Throttle body size at the end of a plenum with tuned runners for fuel injection is a different idea then a throttle body in the middle of a runner.
The first system won't care if you put a 1000cfm throttle body on a 2.3 motor if you like an extremely touchy pedal. However, you would have to build a large set of runners to use 4-250cfm throttle bodys which would kill your velocity, ram effect and so on. I'm not a pro so this is only an opinion.
And can someone give me some info on webers and Dellortos? Is the 45 and 48mm the measurement of the venturi or the throttle size? It's been along time since high school and the old '67 baja with 44's and the 1835.
Hi Cheapracer as far as I know 45mm webbers have a 45mm bore size which would be the same as the throttle size I just had some chokes made up they are 42mm chokes and messure 45mm on the out side and they slide in a very neat fit but also I am no expert
I still have not found out what size throttle bodies to use 4x2" may be to big as the old saying goes bigger is not always better I need to find out because its holding up the project.
ok I'm thinking (yes I know I'm not exactly equipped for that but anyways LOL) If you were running a multicarb setup you could simply find out the TOTAL area of the throttle plates then divide by 4 to get the individual throttle opening sizes. Does this make sense? or are these just insane ravings at 1:00AM?
if you add the total area of the throttle plates together then devide by 4 wont you have the same answer you started off with ???
If you're getting good performance with the multicarb setup then you could use an injection system that has the same diameter throats. From there if you think you need to go up in size get a system slightly larger
I ran a Holley 390 4v for a year then switched to a single Hilborn 2" throttle body. I did the math once and those two ought to have roughly the same area. My barrel valve ramp is close to but doesn't quite match up with the throttle plate opening. The throttle body is definitely touchier than the carb was, but tuning will be easier if you are running alcohol.
At low RPMs your atomization will be less, but if you are running mechanical you probably don't do a lot of low throttle driving. If you run 1 injector (or more) per cylinder, you can run as much fuel as you want (neighbor down the street runs 2:1 AFR) and still get good atomization as long as you keep the system pressure up high enough. The fuel doesn't puddle in the manifold like a carb or throttle body injection.
Here's the graph of carb-vs-injection on my car.
It looks like crap in that little picture. If you open it in a new window, it's easier to read.
Well the injection definatly wins I like the improved torque curve that you got out of it. I am concerned about the air speed and volumetric efficencey when using 4 x 2 1/8" throttle bodies. I will be using one injector per cylinder but I will put a taper in the manifold so it acts like a venturi which hope fully will increase the VE and airspeed. On the track the engine wont be under 4000rpm so fuel drop out at lower revs should not effect it to greatly
Hey bricker4864
How much do you know about Gallons per hour for the injector pump pill size and nozzel size for the 2ltr pinto?
I'm not sure what you're asking?
I run a -00 pump (.67 gal/min) and 4A nozzles. You pill size(among other things) determines fuel system pressure and air/fuel ratio.
I don't remember all of the pill sizes I was running at the moment, but I have a lot of them in the system.
I know a lot about pills and pressures, so try me one more time.
ok I looked back through your posts and came up with this:
Assumptions Made:
Peak Torque: 7500 RPM
Volumetric Efficiency: 90%
Temperature: 59*F
Barometer: 29.92"
Air Density: 100%
Facts
Fuel: Methanol
Cylinders: 4
Cubic Inches: 122
Equipment
Nozzles: 8A Hilborn
Pump: -0 Hilborn
Drive Ratio: 1/2
Main Pill: .100 Hilborn
Bypass Pill: .041 Hilborn
Bypass Spring: 75 pounds
That gives you a 5.16 air/fuel on the main and a 5.9 air/fuel on the bypass
You are on your own with the barrel valve! The bypass spring seems heavy to me. I would think something in the 50-60 lb range more appropriate, but maybe not?
Note: If you use Kinsler pills, run a step or two richer. The radius they put on them makes them flow more, leaning out your system.
Bigger pill=leaner, smaller pill=richer.
thanks for helping me out with my home work man well done
what I have been reccomened to run is this
Size #0 fuel pump
Main jet .110
Hi-Speed 38psi
12% leakdown on the barrel valve
if you run 10 to 15% nitro...
richen the jet .015 to.020 on first 10%.
the primary by pass valve stamped with a #4. You should run size 14 nozzles. The size #0 pump will flow 3 1/2 gallons at 4000rpm with 100psi.
the only real big difference I can see is the nozzel sizes
All this alcohol/ nitro stuff is out of my league! This guy lives about 3miles down the road from me. I learned a ton from him when I switched my car over to fuel injection.
Here's his Nitro Notes http://onehotchilipepper.com/nitro/.
The main page is http://onehotchilipepper.com/
hey bricker what times have you run over the eighth I have only run an eighth the closest 1/4 mile track is over 2.5 hours drive away :(
My quickest 1/8 mile is 9.980, 10.0 times are more typical, 67mph.
I've got 4.62 in the rear end, 3.99 1st/2.14 2nd/ 1.42 3rd. I shift into third just before the 1/8th. If I were just running an 1/8 mile I'd cross the line in 2nd and probably be a little qicker.
Yourself?
My best 1/8 time is 9.08 last time out I ran 9.24. My engine is 2ltr with twin 45mm dellorto carb's 10.5 to 1 comp running premium unleaded (98octane) on street tyres I also change into 3rd just before the finish line I run a 3.9 diff with 195/60/14" tryes. I have held it in second to see if it would be faster the revs went up to about 8000rpm I say about because I was really nervous and thought it better to watch the finish line so I could back off as soon as possible and not blow everything to pieces it was slower. Peak power is at 6000rpm I usually change at 7000rpm then it drops to 5000rpm and its good on the cam changing at 6000rpm drops the revs to 4000rpm and it bogs down a bit because it has dropped of the cam.my first gear ratio is 3.656 2nd 1.97 3rd 1.37.the motor is good for 130hp at the wheels. I have been trying to run an 8.?? for years with this set up with no luck so far I would like to beat the twin cam fuel injected import cars that are turning up to the track thats why I am going the methanol injection route.
Bricker I been waiting to see what you thoughts were on what my car runs but no coment yet. My injection system is coming along nicely just got to order the nozzles and injector hoses have been able to source everything else locally.
Quote from: non profit on December 16, 2004, 04:04:38 PM
My best 1/8 time is 9.08 last time out I ran 9.24. My engine is 2ltr with twin 45mm dellorto carb's 10.5 to 1 comp running premium unleaded (98octane) on street tyres I also change into 3rd just before the finish line I run a 3.9 diff with 195/60/14" tryes. I have held it in second to see if it would be faster the revs went up to about 8000rpm I say about because I was really nervous and thought it better to watch the finish line so I could back off as soon as possible and not blow everything to pieces it was slower. Peak power is at 6000rpm I usually change at 7000rpm then it drops to 5000rpm and its good on the cam changing at 6000rpm drops the revs to 4000rpm and it bogs down a bit because it has dropped of the cam.my first gear ratio is 3.656 2nd 1.97 3rd 1.37.the motor is good for 130hp at the wheels. I have been trying to run an 8.?? for years with this set up with no luck so far I would like to beat the twin cam fuel injected import cars that are turning up to the track thats why I am going the methanol injection route.
Have you thought about running a 4:30 rear gear and shifting into 3rd? The 4:30 will launch the car better and shifting into 3rd will "pull" you through the finish line insted of running it through at 8K and loosing power???? just my 2c.
When I first started out because I was going drag racing I thought I need to run low diff gears so I put a 4.4:1 set in I ran the car like this for some time I also road race the car and I had meetings on two weekends in a row I knew the 4.4 was no good for the circuit so I put 3.9 in and could not be bothered to change them for the drags so I thought I would see what difference it would make. The car was consistantly 3to 4 tenths quicker. Now I dont know what caused this wheather the car has less wheel spin with the 3.9's or it allows the motor to use the torque and pull through the gears better not sure but it is faster with the 3.9
Huh...................... ???
I know I cant figure that out either.