frito1

iTrader: (12)

I've always wondered....seems like the two inside cylinders would get more air with the shorter runners. Maybe my plugs tell the story.

EDIT: I apologize for these being cathedral ports in the gen IV section but I'm sure the airflow does the same thing with the rect. ports Vic Jr. Just thought I'd get a more in-depth discussion here.

fuel

iTrader: (13)

do you think its gas or oil that has made it turn black

1BAD_LS1

iTrader: (36)

interesting!

frito1

iTrader: (12)

That's fuel... no oil on the threads.



Has anybody else with a EFI Vic Jr pulled their plugs out and seen the same thing? The wideband shows ~12.8 AFR at WOT. It's getting the average of this mess going on here. So I have 4 cylinders going pretty lean and 4 going pretty fat. I'd appreciate other EFI Vic Jr owners to pull plugs and chime in.

frito1

iTrader: (12)

I think this is pretty big deal so I talked with an edelbrock rep just now. I emailed him the pics and he is going to send it on to the engineer. I doubt that will go anywhere. Of course they have never had any complaints.... but who pulls their plugs just to check?

87silverbullet

iTrader: (11)

The nitrous guys do. Just post in the nitrous section and some guys with the vic intake will chime in and help. The forced induction guys see things like this too so they might be able to help also

OUTLAWZ RACING

iTrader: (9)

I had the vi jr and intake elbows and 90 mm t body my plugs where even across the board. My car ran better with the vr jr vs a fast 90.

Pwebbz28

iTrader: (31)

My GMPP single plane doesn't do this. The runners are pretty much the same length. They look shorter fro
the outside but from the inside it's different.

danbap

iTrader: (6)

i pulled my plugs out of a blow through carb vic jr d1sc set up and all my plugs looked the same except 1 and 3 were a little darker

frito1

iTrader: (12)

Is this a carb setup or did you drill the bosses for injectors?



Thanks for the info but carb setups won't be apples to apples BECAUSE the correct AFR is there to be "had" (assuming the carb is set right). The cylinder just has to pull that mixture in (or get pushed in if it's forced induction in your case). Basically they get what they can get of this perfect mixture. The cylinders pull it past the jets. EFI is averaging the AFR and shooting the same gas amount of gas to the cylinders... the wildcard comes with some cylinders can pull more air or less air depending on runner length/shape yet every cylinder gets the same amount of gas.

1320

iTrader: (6)

I would bet this is due to the throttle body linkage. If you install fresh plugs , make a pass, and shut it off clean.....it probably wont be the same. I think its due to the air entry at the throttle body blades, during low speed, closed throttle situations. (ie just driving around)

Kevin@Vengeance

iTrader: (11)

I've done both the Jr. & S. Vic using both an elbow and 4150 Carb style Tb. on LS based motors...

The elbow works well for FI/blow through apps., but is not as efficient as the carb style TB on NA motors. The air entering the elbow also has to make a 90* turn before it enters the plenum... air doesn't like to turn corners or change direction.

What you're seeing is in fact the outer holes running fat and the inside cylinders running a bit lean as the incoming air has to make a 90* turn to enter 1-2-7-8 cylinders and the inside holes have a straight shot.

I've personally seen a 30rwhp/22rwtq loss down low with the Vic style intake over the FAST using a decent sizes single pattern cam, and what it picked up on top wasn't even a wash.

The only fix is to run a stand alone OS, monitor EGT's and tune A/F for each hole individually... you can also play with plugs to get it a bit closer.

Also keep in mind the camshaft/valve events/CR's that would be typical of a OEM or FAST intake are not going to be optimal with a single plane/short runner'd intake.

dlove

iTrader: (23)

this car has a 4 barrel throttle body setup. not an elbow.

fieroguru

iTrader: (1)

If the 4 inside cylinders are seeing more air and that is just the way it is, you might want to run a slightly larger injector in the 4 center cylinders or find some other way to add more fuel with the increased air.

Slowhawk

iTrader: (12)

I've seen that with small 90 elbows like the edelbrok.When we run a bigger elbow the plugs run even. So,I would gues that a 4150 setup would do the same thing at idle/part throttle due to the lack of volume in the intake.

My super victor with 105mm elbow/TB setup has all the plugs running even on color but I did port it and opened up the outside runners more.

carlrx7

This!