turbo2256b":2a1eks81 said:
I used to design turbos for Schwitzer Corp. We turboed several test engines for Ford including a 200 and 250 6s they were all blow through. Ford wanted us to do them in a draw through style we told them to shove it as we would not want to be involved in the warranty issues that would be involved.
Ford didn't want port EFI, and didn't want to relinquish the carb, and they were debating going to TBI in a turbo.
There's a reason Ford USA never went blow through aside from the first Paxton supercharged T-birds and 57 Fords and the 67 Shelby's....
if a blow through carb ruptures a power valve or collapses a float or has a in service fuel delivery problem, in the words of Assistant Chief Engineer for the 79 Mustang 2.3 Turbo
Same with the blow through 1985 4-bbl Saleen PaxtonMustang conversion; should have been a shoe in for CARB emissions certification, but even the most excellent car sorters in the world had so many problems making a blow through carb work and be legal and safe, they avoided blow through carb instillation for years.
Gale Banks, Austin Rover's MG Metro 1275/ MG Maestro2000 and Ford of Europes 2.8 Capri Turbo and Alfa Romeo's TurboDelta and the Lous Esprit Turbo were the best blow through conversions. The R5/R18/Feugo Renault Solex 1-bbl blow through carb instillation weren't very reliable because of in service fuel delivery problems.
My summary? Norm General from Ford was right, but if your carbs are in good shape and you have a good, robust and well sorted fuel air distribution and linkage, then a blow through makes sense.
I think creating EFI style fuel enrichment through an aircraft leaning device and mapping it, would have allowed Ford to shut off the power valve entirely...like
http://www.rotaryeng.net/HOW-TO-INSTALL-HOLLEY.html
You'll understand how the Holley Aero altitude leaning system by Tom McNeilly?
On a good old 2-bbl 4412 500cfm Holley, the air horn gets machined off like what was done on the factory Six Pack Mopar carbs
Or a 4BBL
If the 2-bbl without an air horn is placed where the stock 2-bbl its is now, you'll get 1.75" of height off the carb.
With the Fox body 250 i6's conversion I do, a very good kit to eliminate the air horn on a 2 or 4-bbl Holley is this kit. Since most Holley 500cfm carbs on a 302 find the 73 jets too rich, and the stock 60F's on the motorcraft 2150 just a little lean. With this kit, you won't have rejet a Holley 2-bbl 4412, and you can get things under the hood, you can trim off the choke horn, and use the aviation Tom McNeilly throttle lean device, and never have to change the jets again. It produces 150% rich on straight up setting, then about 1/4 turn or so in a position that has to be determined by time on an exhast gas analyser or dyno , it drops back to the required jet size. If you do a dyno run with this, you could produce optimum jetting by measuring the degrees of movement of the carb float mounted crank.
For cold starts, it would get shifted upright via a bowden cable, and then throttled back to that positively stopped position when its warmed up. Its like a Percy's adjustajet, but it produces a much better 'roosters tail' of fuel atomisation. As Ford found with the need to put eye brow interrupters into there CFI intakes, 2-bbl Holleys aren't great at fuel distribution, but the kit is from
tomcn@earthlink.net for US $150 dollars excluding post and packaging.
These are throttle leaning devices used for light aircraft, see
http://www.rotaryeng.net/HOW-TO-INSTALL-HOLLEY.html
It is best suited for a two barrel 350 or 500 CFM Holley carburetor. However, the unit has been successfully used on large four barrel carburetors. The mixture control WILL NOT fit other makes and models of carburetors! The unit replaces the fixed main jets with a rotating valve that is remotely operated by a push pull cable. The unit will go from total idle cut-off to overly rich by rotating the shaft, while the engine is running. Installation is very simple with step by step instructions provided.
Due to the outrageous cost of materials and the inflationary state of our economy,the price of the kit has recently been raised to $150.00.
The mixture control body is CNC machined from 6061-T6 aluminum which is alodine treated, the shaft is stainless steel and the screws are plated steel.
The first picture is what comes in the kit. The mixture control plate is in the background with the accelerator pump extension arm., power valve block off plug, and installation bolts in the foreground. I also include a set of three gaskets which are not shown.
-Tom McNeilly
14001 East Williams Field Rd.
Gilbert, AZ 85296
International phone number is +1-602-899-7613
He's in Arizona, USA.
Northwest Aero Products also has them available. They are at
13812 179th Avenue SE
Monroe, WA 98272
International phone number +1-360-805-8183
Call displayed telephone number to ask for respective email address of Northwest Aero Products.
Follow those recommendations and you'll be able to adjust total jetting via a simple line of feedback code from Audrino.
Add TPS, and you can seamless resolve air fuel mapping by narrow band and an open/closed loop code test.