dlove

iTrader: (23)

what is the better option?

1. gmpp with a 4150 to 4500 2'' adapter?



2. gmpp machined to have a 4500 flange on it?



I almost think the adapter one because i have read that the volume of the intake is not very much. Wouldnt the adapter help with the volume issue?

But then what about the flow loss or even maybe gain from necking down to the 4150 flange?



I almost want the intake machined to have the 4500 flange so i can have some hood clearance back!

2000_SS

iTrader: (24)

hood clearance is good, but i would opt for the greater plenum volume, especially if it's a NA application. if you machine the flange down to a 4150, i'm sure you'll still make power, but i don't think it would have the "gains" you might be talking about, if you're referring to a smaller opening creating a little velocity...

my .02

dlove

iTrader: (23)

i think you are backwords

the gmpp is a 4150. my tb is a 4500. i have an adapter that goes from the 4150 to the 4500, but it puts it up pretty tall. good for the extra volume. But not sure if i will lose anything(other than volume) or gain anything by having the gmpp machined to a 4500.

2000_SS

iTrader: (24)

oh.....gotcha...well since you have the adapter, just try it first. as long as you don't have to cut up your hood to clear it, it you won't be out any extra money right? if you don't like it, try it the other way.

dlove

iTrader: (23)

i have it like that now. thats why i'm asking this question. There is very little hood clearance. Thus I want to know if I will gain anything by getting rid of the bottle neck from the 4150 or is the added volume more important.

sorry, maybe im explaining it bad but you seem completely lost in what i have and what im doing.

KCS

iTrader: (20)

I would think that the taller throttle position would give the air more area to turn into the runners, seeing how low the manifold is. But whether or not more plenum volume would hurt or help, I don't know. The new Edelbrock Super Victor manifold is at least 2" taller than the GMPP or Vic Jr though.

KCS

iTrader: (20)

Your sig is f'n awesome though, lol.

JL ws-6

iTrader: (50)

I would have the intake machined to put the 4500 right on top of the intake, and then port the inside of it as much as possible ot increase the volume some.

I remember reading something in an old hot rod about this very topic, and the issue they had was that on an engine dyno the car did make a touch more with the spacer then it did with the volume ported intake, but the problem was that it put the TB too close to the top of the hood which restricted the intake flow, so that in the car it was better with the volume ported (as well as port matched, for both comparisons) intake. I think I remember them taking like 30cc's of alum out of an edlebrock intake from just thinning it out everywhere that they could.

dlove

iTrader: (23)

did some testing. I ran back to back runs with and with out my hood. Ran the same time.

I have the rear of the hood shimmed up to let in more air.

My logs (kpa, gm/sec) show the same reading as well.

So for now im keeping the spacer.

94 guy

iTrader: (125)

have you dynoed with the single ever?

dlove

iTrader: (23)

probably wont ever, 5000 stall kinda throws dyno numbers off

JL ws-6

iTrader: (50)

I wonder what having the hood off did to the car's aerodynamics, and if that would possibly skew the results of the test any.

If you had a big 6 inch rise hood on the car I'd think it wouldn't matter, but if the stock hood, or stock height I can't imagine it's not effecting the airflow in some way.