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  #31 (permalink)  
Old 02-09-2011, 02:42 PM
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Quote:
Originally Posted by ap72
can anyone explain to me why people assume the 302 was underrated? It had crappy heads )by today's standards), a lazy cam, no significant displacement, poor intake, poor exhaust, poor ignition. The only thing it did have was compression.

I hear this was "underrated" all of the time, but if you ran it by today's dyno standards I think you could only hope for 290hp.
Compare the cam specs to to the displacement to the RPM where the HP was taken, for one thing. I believe the cam would have peaked at 5800 in a 327 or maybe a 350, but not a 302. In a 302 I'd expect that cam to reach peak HP in the high 6K RPM area, at least.

The correction factors today are tighter than back then, yes. But comparing the same correction factors would be the only fare comparison.

The 302 used ram horn manifolds but given the displacement, that is less of a hindrance than it would be on a larger engine- and were the same manifolds used on the 327/365 HP engine.

I wouldn't call the intake "poor", either.

The whole idea was to keep the engine from producing over 1 HP/ci- on paper. I believe the engine was capable of producing upwards of 350 HP at peak.

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  #32 (permalink)  
Old 02-09-2011, 03:19 PM
How fast is fast enough?
 
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The ram horn manifolds don't provide any scavenging, and the cam only had about .450" net lift, with heads that flowed about 180cfm at that lift level, a cam that was very lazy, nothing other than high compression.

I don't doubt the power cut off at 5600rpm, you're pushing it through exhaust manifolds with way too much duration, it was backing up at that point.
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  #33 (permalink)  
Old 02-09-2011, 04:01 PM
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Then what do you say about the 327/365 HP engine- that a lie too?
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  #34 (permalink)  
Old 02-09-2011, 06:24 PM
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Look at the power output in classes restricted to running manifolds. And consider all the advancements those engines are running. A lot of the power figures were calculated, not measured. They probably assumed things to be better than they were on those engines.
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  #35 (permalink)  
Old 02-09-2011, 06:39 PM
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Quote:
Originally Posted by ap72
The ram horn manifolds don't provide any scavenging, and the cam only had about .450" net lift, with heads that flowed about 180cfm at that lift level, a cam that was very lazy, nothing other than high compression.

I don't doubt the power cut off at 5600rpm, you're pushing it through exhaust manifolds with way too much duration, it was backing up at that point.
Here is a good article for you... http://www.chevyhiperformance.com/te...ory/index.html


The 302 was just getting warmed up at 5600rpm.
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  #36 (permalink)  
Old 02-09-2011, 07:11 PM
How fast is fast enough?
 
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According to what? I didn't see any evidence of that in the article.
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  #37 (permalink)  
Old 02-09-2011, 07:40 PM
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Quote:
Originally Posted by cobalt327
Then what do you say about the 327/365 HP engine- that a lie too?
So, no comment?
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  #38 (permalink)  
Old 02-09-2011, 07:49 PM
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Quote:
Originally Posted by ap72
According to what? I didn't see any evidence of that in the article.
Copied from that page:

The 302 Z28 engine is the smallest V-8 ever installed in a Camaro to date. It is also the only engine available new in any '67-69 Z28. Based on a 4.00-inch bore and a 3.00-inch stroke, the little engine made lots of power above 5,000 rpm and very little below. This engine's 290hp rating was very underrated. In stock trim, actual power was in the mid-300hp range. These engines were designed specifically to compete in SCCA road racing and came with a huge resume of hardcore race parts: a Holley 800-cfm carburetor, big-runner aluminum intake manifold, 2.02 heads, a high-lift mechanical camshaft (0.485-inch lift), 11:1 compression, full-floating wrist pins, a forged crankshaft, and more. Because the engine did not produce much torque and had such high rpm capability beyond 7,000 rpm, 302 Z28s were only offered with four-speed transmission and were not available with air conditioning. Chevrolet also sold several cross-ram-intake setups (two staggered four-barrel Holley carburetors) and special race camshafts for the early Z28s that helped the 302 gain even more high-rpm power. With some modifications these engines would easily produce power well above 400 horses (at very high rpm).
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  #39 (permalink)  
Old 02-09-2011, 09:22 PM
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Quote:
Originally Posted by prostreet6t9
4.00-inch bore and a 3.00-inch stroke
Holley 800-cfm carburetor
big-runner aluminum intake manifold
2.02 heads
a high-lift mechanical camshaft (0.485-inch lift)
11:1 compression
full-floating wrist pins, a forged crankshaft
Et cetera.

Yep- sounds like a 275 HP engine to me, all done by 5600 rpm!
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  #40 (permalink)  
Old 02-09-2011, 09:36 PM
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The manifold's runners were big compared to a stock 283 intake, relatively tiny as were the head ports. .450" net lift (not .485") the holley didn't flow that much (again calculated flow not measured) and the exhaust was a huge bottleneck (ask anyone who swaps headers onto any stock sbc).

Its all misconstrued hype. The biggest reason that car felt fast was that it made a lot of noise smelled of gas and had really steep rear gears with a manual trans.
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  #41 (permalink)  
Old 02-09-2011, 09:56 PM
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Quote:
Originally Posted by ap72
Its all misconstrued hype.
Tell it to a REAL ENGINEER, Rodger Huntington. These are the lowest figures I've actually ever seen that were supposed to be correct, yet they STILL have the 302 well over 300 HP. From HERE:

Make/---------------Adv.-------Adv.---------Actual
Engine size-----------HP--------Torque-------HP

Buick 455 Stage 1----360@5000--510@2800--420@5400
Camaro Z-28 302-----290@5800--290@4200--310@6200
Chevelle 396 L-78----375@5600--415@3600--400@5600
Corvette 427 L-88----430@5200--450@4400--480@6400
Mopar 340------------275@5000--340@3200--320@5600
Mopar 440-4 bbl------375@4600--480@3200--410@5400
Mopar 440-6 bbl------390@4700--490@3200--430@5600
Mopar 426-Hemi------425@5000--490@4000--470@6000
Mustang Boss 302----290@5800--290@4300--310@6200
Ford 351 Cleveland---300@5400--380@3400--340@5600
Mustang Boss 351----330@5400--370@4000--360@6000
Mustang 428---------335@5200--440@3400--410@5600
Mustang Boss 429----375@5200--450@3400--420@5600
Olds 455 W-30-------370@5300--500@3600--440@5600
Olds 350 W-31-------325@5400--360@3600--350@5800
Pontiac Ram Air 400--366@5100--445@3600--410@5600

Written by Roger Huntington of the Society of Automotive Engineers
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  #42 (permalink)  
Old 02-09-2011, 10:50 PM
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Quote:
Originally Posted by ap72
The manifold's runners were big compared to a stock 283 intake, relatively tiny as were the head ports. .450" net lift (not .485") the holley didn't flow that much (again calculated flow not measured) and the exhaust was a huge bottleneck (ask anyone who swaps headers onto any stock sbc).

Its all misconstrued hype. The biggest reason that car felt fast was that it made a lot of noise smelled of gas and had really steep rear gears with a manual trans.
Cam Part# 3849346 Pretty sure its 485 lift and 254 duration@ .050

I believe there was 2 other larger GM Camshafts options also. I'm not saying its the best motor ever built but to call it hype is a little silly. Those things could really run. Ever heard about the "Old Reliable"? Granted they have they help of one of the best engine builders, but look at the specs: Copied from Camaro Hi performance.

Build Date 04A (first week of April)
Color Corvette Bronze
Interior Code 712, black standard
Car Shipper Shipped on April 11, 1968 to Ammon R. Smith Auto Company, York, PA
Engine Data Cubic Inches, 302
Cylinder heads #3917291, completely stock, no porting allowed!
Stock rocker arms & valve springs
Intake 302 aluminum intake, casting #3917610
Carburetor Holley, #4053, 780 CFM 4bbl
Camshaft Crane, .480 inches lift, 272 degrees duration, valve lash, .016-.016
Pistons GM 302, .030" oversize
Horsepower 456 @7700rpm
Rear Tires 9" x 30.0" Hoosier's
Rear axle & ratio 12-bolt, 5.57 Richmond Pro Gears
Clutch 10 inch, three finger from Advance Clutch Technology
Shift Points 8200 RPM
BEST ET 10.80 @122.30mph
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  #43 (permalink)  
Old 02-09-2011, 10:53 PM
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Quote:
Originally Posted by prostreet6t9
Cam Part# 3849346 Pretty sure its 485 lift...
That's gross lift. Subtract the lash for net.
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  #44 (permalink)  
Old 02-09-2011, 11:43 PM
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Quote:
Originally Posted by cobalt327
That's gross lift. Subtract the lash for net.
Point well taken. and I believe its supposed to be .030 lash. Whats amazing is the crane cam used in old reliable was a tad smaller lift but more duration. I believe in the "stock" classes they have to stay within stock lift specs but are allowed to play with the duration.

That car had stock rocker arms and valve springs, NO headporting and made 456HP @7700 and they spun it to 8200. For using stock parts and a set of stock heads that people claim make no power and are old technology,That car Hauled the mail! I'm sure having Grumpy involved didnt hurt much either.
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  #45 (permalink)  
Old 02-10-2011, 07:17 AM
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Quote:
Originally Posted by prostreet6t9
That car had stock rocker arms and valve springs, NO headporting and made 456HP @7700 and they spun it to 8200. For using stock parts and a set of stock heads that people claim make no power and are old technology,That car Hauled the mail! I'm sure having Grumpy involved didnt hurt much either.
No doubt! That was a Biscayne, wasn't it? Not exactly a little car if it was.
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