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Discussion Starter · #1 ·
My motor is this:
350 30 over 355
Forged steel crank new
HP rods New
Balanced
9.5 Speed Pro Pistons
64 cc Edelbrock RPM Heads
Headers
65K Volt HEI
Double roller timing chain
Weiand xcelerator intake ( i think it sucks )
Holley 4777 650 Double Pumper with electric choke
Comp Cams 270 xe
Alum Roller rockers Comp Cam

Has power lots of it, I have been talking to several Small Block friends (i have NO experience with chevy performance) I have been told the set up should be 380-400hp but the intake and maybe carb is holding back much more torque and mid range hp maybe some top end.

I have been told the weian xcelerator is OLD SCHOOL and VERY OLD tech and the performer RPM and a 670 or 770 Holley Vac secondary will make the power band and toque much more useable..


1. Whats you guess on current HP given the parts

2. Whats your opinion of the performer RPM intake?



I was thinking of running a drop air cleaner or the edelbrock lynx.


Thanks in advance fellas
 

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The Performer RPM is generally understood to be about good as it gets for a dual-plane intake, perfect for your application. No way that carb. is holding back that engine. A bigger carb. would actually lose a little torque down low and in mid-range. Your horsepower you listed sounds about right. I hope you have a good 2-1/2 inch exhaust and free-flowing mufflers.
 

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Discussion Starter · #3 ·
Its a mechanical secondary 650 on an open plenum intake, it. My upgrade will be performer rpm intake and after talking to Holley, edelbrock and the engine builder they say an 670 or 770 street avenger would be perfect for my daily driving chores and highspeed runs up the dallas north tollway. LOL

Super chevy sunday is next weekend. I think I may be able to get a small discount on the purchase of the intake at the races.


So whats your thoughts on the HP rating?
 

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The Performer RPM is generally understood to be about good as it gets for a dual-plane intake, perfect for your application. No way that carb. is holding back that engine. A bigger carb. would actually lose a little torque down low and in mid-range. Your horsepower you listed sounds about right. I hope you have a good 2-1/2 inch exhaust and free-flowing mufflers.
IMHO, the above is right on the money, although I'm not good at HP estimation.

The technical back-up for the above is a simple formula.

Air Flow Requirement = (displacement x max rpm x volumetric efficiency)/3456. Using 6200 as a redline, you get 355 x 6200 x 1.0/3456 = 637. That's at 100% volumetric efficiency, your engine is between 0.80-0.85 VE. So even at 0.85 (a race engine), the carb air flow requirement is only 541 cfm. The 650 cfm is plenty big. If you go bigger, you pick up very little HP and lose some on the low end.

If you want to spend more time looking into the carb sizing, go to www.secondstrike.com, go to "Technical" and then "Carb Calculator". The calculator uses some basic formulae from Holley and figures out the air flow requirement and horsepower loss from the restriction of different size carbs (using pressure dropcalculations). I assumed your engine was making 400 HP at 6200 and that 6200 was the redline. (You can input the right numbers, it won't change the results much.) The results show with the 650DP you could punch it at 1232 rpm and go WOT with no stubbling. If you switched to a 750 cfm carb, you would pick up a wopping 3.3HP, but the "Punch it" rpm goes up to 1527. So you can see that the throttle response goes down for just a small gain up top. Not worth it. It is easy to over-carb an engine and you're getting bad advice from those that are pushing you to go to a bigger carb.

Your money would be better spent on a new dual-plane manifold. I have a Performer RPM on my engine now, great manifold.
 

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Discussion Starter · #5 ·
Ill let you guys know, for an auto tranny I would bet overall drivability and mileage increase. I have a street avenger Vacuum secondary, I will be putting on tomorrow. It is a 770 cfm, Performer RPM intake will be put on this weekend I bet.
 

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Ill let you guys know, for an auto tranny I would bet overall drivability and mileage increase. I have a street avenger Vacuum secondary, I will be putting on tomorrow. It is a 770 cfm, Performer RPM intake will be put on this weekend I bet.
It looks like you convinced yourself to use the Holley 770. Don't give the 650 away...you might be putting it back on.
 

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Discussion Starter · #7 ·
It looks like you convinced yourself to use the Holley 770. Don't give the 650 away...you might be putting it back on.
I have a few, I may even try an AVS.

But thats the fun of this stuff. My garage and my tools give me solice after a long day.
 

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Discussion Starter · #9 ·
What's your current 0-60 time?

Dont know, Ill hit dyno this weekend or next and check A/F ratio for jetting.

I am still sroting out minor issues, tires, cooling. etc.

PO didnt install fan shroud correctly, Fan clutch is stuck locked up (I sound like a street sweeper drving around)

After CCC was removed still some wire conectors hangin around that need to be cleaned up, and its summer car show time so I have a restored 70 Wagoneer we take to car shows on the weekend so I dont really move as quickly on things as I would like.

By scotiapilot at 2011-05-30
 

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Discussion Starter · #10 ·
Scored a new in box 7101 Edlebrock rpm tonight off craigslist with intake gaskets and ARP bolts for 150. Gotta love craigslist.

Guess I will slap it on tomorrow.
 
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