DeltaT

iTrader: (5)

I'm thinking of doing a side-mount, A2A-intercooled Whipple 3.3 on the 434 SBC I'm building, but am a bit concerned about the instant off-idle torque blast. Either I pulley up and limit total boost and power or figure out how soften the hit a bit.

The 434 alone is going to have some traction issues. I'm already planning to change the rearend ration from 3.73 to probably a 3.23 gear.

Any other ideas? Comments? Please - No 'do a turbo setup' comments though - that's not happening.

Thanks,

Jim

PS This is a G-body project with a built 4L80E. Target is a great all-round driver that also holds its own up with anything to about 150mph where my Malibu 'barn-door' aerodynamics will really kill me.

VINCE

iTrader: (1)

Try a HUGE cam that will push the powerband higher in the rpm. That should soften the blow..

ninetres

iTrader: (35)

Big tires.

slow67

iTrader: (2)

You could bring the wot timing back a little bit in those areas

99.9percenter

iTrader: (2)

Right foot (throttle) control.

engineermike

My vote is to use a very late IVC. This will kill some low-end and increase top-end, without affecting idle quality or fuel mileage.

Most performance cams use an IVC between 40 and 50 deg ABDC. You could go to around 55-60.

Mike

RW99

I say re-learn part throttle if at all possible... you're in a better position than us turbo guys that are losing traction: you can kinda roll into the throttle, while we have to try to get the turbo spooled with initial WOT and then pedal back just enough to keep traction.

ninetres

iTrader: (35)

True. Good advice. Just roll into it more. Sounds simple enough.

Drew04GTO

iTrader: (1)

Don't have a lot of experiance with this but how about using an auxillary output on your ecu to crack open the bypass on the supercharger? Could be as simple as a solenoid with adjustable mount and 12v switched power.

DeltaT

iTrader: (5)

Thanks - some good ideas. The bypass valve one is what I was thinking - I do have a couple ECU Aux outputs. Definitely expecting to learn new throttle control

Not a problem I ever expected to be thinking about! The past ten years have opened up so much more in performance it's just just stunning. What a cool time to be into cars...

Mike - I already got this new solid roller to try with the Vortech, so I'm gonna give it a try on the Whipple and see what happens: 9.5:1 CR, cam is 242/248@.050" on a 115lsa, .60x/.61x net lift). I think it's too short to qualify for your idea, eh?

Jim

engineermike

You could put it in 4 deg retarded. That would put IVC at 60 ABDC.

Drew04GTO

iTrader: (1)

Awsome idea IMO. I bet if OEMs had this same problem they would look into this route. Don't know much about your ecu and how the aux outputs work (discreet or analog?) but I bet a linear stepper motor off some random car used for an idle air control valve (type that actuates throttle plate) would be great for this task. Only issue that I see arising is its just one other thing to tune when you're taking care of all that. Not to mention the fact you're probably the first person I've heard of trying to limit boost down low, ecu controlled or otherwise.

I mentioned this thread to one of my co-workers earlier today with a works 2.3L Lightning and his reply was "why doesn't he just put a bigger tire in the back?". Had a hard time not smacking him, I realize sometimes people arn't willing to tub a car and there are space limitations. Must be nice to fit a 30x16.5-16 slick out back without any modifications

Johny GTO

dont be retarded......



the answer lies in that

DeltaT

iTrader: (5)

Lowering DCR?

Jim

engineermike

Exactly.

Drew04GTO

iTrader: (1)

Why change the powerband all over when you can just effect everything below whatever RPM you want. If DeltaT wanted to get fancy with it he could use this as traction control also if he uses the ECU/stepper motor. Honestly while retarding the cam is easier it seems ignorant. There's plenty of other good ways to kill power down low other than messing with cam timing.

*edit* 4 degrees of cam timing is A LOT. I could understand this approach if it was just effecting the intake but not when all the lobes are on a single cam.

longrange4u

iTrader: (2)

I know it was mentioned already... but alot of the guys have been playing with lower gear ratios... like 3.23 and below.... there are some turbo guys that are runing 2.70's on the board but I dont know how that would translate to an S/C application...

Websy21

iTrader: (34)

Hmmmmm, good point I was thinking of going 3.25 myself and no bigger than 3.50 of course with my turbo but I think the s/c need a bit lower gears than us turbo guys though

lt1s10

iTrader: (2)

You would have to use a servo or a stepper motor to control the bypass.

Johny GTO

I honestly dont know all that much about motors. It was just a kinda simple way to do it that i could think of.
Also, wouldnt changing the opening or closing of the valves (intake or echaust) cause u to lose some torque down low perhaps?