chevydad

is there a difference between a came for a efi motor and one for a carbed motor? like would a t-rex or similar cam work well in a lq4 with a carb and victor jr intake?

Ed Wright

iTrader: (1)

I don't see whay they would be different.

Patrick G

iTrader: (14)

A carburetor doesn't necessarily require any different LSA than EFI, but a different style intake may. A single plane intake with unequal length short runners is going to want different valve events than running a FAST intake.

ChucksZ06

iTrader: (9)

They will both work but the engine can be made to run smoother at all rpms with efi vs a carburator. With a camshaft with lots of overlap the engine does not have a good signal to the carb(low vaccum) and the vacumm is what pulls the fuel out of the carb into the intake...with efi you can give the engine the best a/f ration at any given rpms...hence smoother idle and midrange than a carb as well as better economy.

mrdragster1970

I was thinking along the same lines ^^ the signal to the carb is very important.
I would ask an expert if you're going for max HP.

chevydad

so what your saying is they're the same.

Nine Ball

iTrader: (38)

should be the same. As long as the proper A/F mix is reached by the combustion chamber, that is all that matters between EFI and carb.

andereck

Well how about this, an efi cam in a carbureted vehicle will run fine and generally have excellent driveabily and sacrifice some performance in the upper rpm ranges and way down low off idle. A carb combination specific performance cam would generally be considered too rowdy for most long runner efi engines.

chevydad

why would a carb sacrifice power down low and up high compared to efi?

chevydad

is there a formula to figure out what vacuum will be on a a certain motor a cam.

andereck

Carbureted intake manifolds generally have shorter runners than efi with the exception being an LT1. Long runner intakes are where efi has the advantage. You just couldn't have a long runner manifold on a carbed road car. Some efi manifolds have over 19" of runner length. The longer the runner the lower its resonant frequency. When a runner resonates it creates pulses that help fill the cylinder. Longer runner manifolds help to make more torque at a lower rpm.

If you heat the fuel or intake charge of a carbed engine, such as GM's heated element carb gaskets you gain many of the driveability and economy advantages of efi, but not to the full effect.

airflowdevelop

Most of the EFI grinds that we run in class cars would never work with a conventional carb due to the lack of signaling. It is worth less than 2 percent though.

Dennis

chevydad

a cam with a lsa of 110 will produce more vacuum than one with a 112 0r 113? or does overlap effect vacuum more than lsa?

thehammer69

iTrader: (2)

Overlap can be adjusted by LSA...and the more overlap, the worse the vacuum at low rpms.

Hammer

V6 Bird

iTrader: (15)

They are different, but like stated not by much. 2% I can agree with.