[Diy_efi] EFI--Manifold types

[sc7500]

> Has there been a discussion in this forum regarding the effects of different
> manifold types (i.e., single-plane, dual-plane, etc.) when used with EFI?
> I'm planning a FAST or ACCEL system for a SBC and wondering if the same
> selection criteria apply to EFI as they do (did) to carb'ed engines. I know
> that venturi signal issues are gone, but are the airflow tuning issues still
> relevant?

Howdy G;

Gonna go out on a limb and give an opinion here, keep yer lighters on 
stun, fellow travelers.

I'm assuming that your setup is for the street, or mild street / strip 
action, okay ?

Example 1 -  The Edelbrock TBI to independent injector conversion for 
BBChevys.

This setup is based on a Performer type runner plan - and, according to 
my own dyno results and corroboration from my friends at Edelbrock, it 
needs AT LEAST 1900 RPM to work efficiently for the given maps, and runs 
out of steam around 5200. Perfect for a stump pulling tow engine, tho - 
plenty of torque inherent in that Performer design.

If you tow a lot, or have a big [C/K 2500 / 3500] style truck, this is a 
hot ticket. Mileage improvements over the stock TBI typically run + 4 - 
6 MPG. Honest.

Example 2 - The Holley Ram / MEFI setup that comes standard on Ram 
injection crate engines, and can be purchased separately thru Jeg's, 
Summit, GM, et al

Has a healthy plenum leading to long descending radiused runners. Works 
well from just above idle to around 5800 RPM. Gobs of bottom end, pulls 
hard thru the midrange, and then keeps your toes tingling at the top of 
every shift. Quite a deal, mileage should be significantly better than a 
carb. In my experience, the lure of stuffing one's foot thru the 
firewall is extremely tough to resist... especially knowing that kind of 
power is available.

Bottom line ? The torque curve is still dependent upon aggressive air 
velocity to make power regardless of the fuel delivery system; a 
manifold that doesn't come on below 2500 - 3000 RPM [like a Torker 
single plane] isn't going to react any better with EFI added - but hang 
on to your head sock once it hits the transition above 2200 !

This is all well and good, but leaves the matter of base throttle body 
CFM selection to discuss - I'll leave that can of worms for another DIY 
member to dissect...

> If there was already a discussion, can someone suggets a date range to look
> through?

Good question - I'm too new to know !

Best
-- 
B. T. Corneto
[The Mad Coater]
Occidental, CA

PS - If you choose not to build your own MegaSquirt, spend the extra $$ 
and buy the FAST set up instead of the ACCEL unit - you'll love it.


_______________________________________________
diy_efi mailing list
diy_efi at diy-efi.org
http://lists.diy-efi.org/mailman/listinfo/diy_efi