Delorto/Weber DHLA/DCOE Flow

[robert kenney]

I am building a large capacity turbo charged 4 cylinder and am currently debating how to feed it. Meaning carburation in either dual DHLA 40H's which I own in blow through or a single DHLA 40 or similer in draw through.

I have no data on what a 40/45/48 mm dual choke carb will flow. If I can't get data on these or any of them I'll have no choice but to go with a 350 cfm Holley. I don't like Holley's for the calibration capability.

My Flow requirements are going to be 300 cfm @ max HP.

RK

[Guy Croft]

Hi Robert

firstly let me apologise for not commenting in any useful way on your cam prediction topic. I just don't get the time I used to.

As for carb - they will all flow a lot more than you might think under the effect of a higher (induced) pressure ratio, ie: in non atmo form. Can you tell me the predicted BHP and cubic capacity of this motor?

G

[robert kenney]

Not a problem and to be honest I can't remember the particular post. I'll have to dig to find it.

As for this one which I do appreciate the response to the typical carb CFM rating is 1 psi of Delta P if I recall correctly.

The engine specifics are
Displacement 190 CID (3.1 liter)
4.03In bore
3.750in stroke

HP @ boost= 250 (Nom) @ 8psi
boost levels as high as 14.7 psi (1 BAR)
5500 rpm at that hp
CR 7.5 0r 8.0-1
Present Turbo of choice Garrett GT2859R Seems to map in the sweet spot with my engine estimates.

Really I have two configurations as I have a brand new set of Esprit DHLA40H carburetors. for a blow through setup.
I want CFM ratings to allow mass flow ratings based on expected pressure ratios so some idea of flow and expected Delta are helpful under draw through configs. In a common plenum on which the draw through carb would be mounted one DHLA 40 may be enough.

Thanks in advance
Robert

[Guy Croft]

Ok- understood.

Maybe this may help some at this time:

viewtopic.php?f=1&t=679

1. Data is at 10" water. The airflow depends on the sy choke size of course not the carb barrel diameter.
2. You need to be careful with the ratio of choke dia to barrel. To get a decent fuel signal and if tuning for max power, typically do not exceed 85-88% ie: 40 carb 34mm choke, 45 carb 40mm choke, 48 carb 42mm choke. You can work out the ratios from that.

G

[robert kenney]

Thanks Guy,
I apprceciate your time.
I do however suspect the flow has a few more variables then orifice calcs. The standard orfice flow calculation would be close and maybe close enough. I have access to a late model flow bench that I could run a flow test on. Just seem to run out of time with things now days.

RK