GMs HP RATINGS

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vortecpro
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Re: GMs HP RATINGS

Post by vortecpro » Tue Oct 17, 2017 8:55 am

A NHRA D/S prepped 302 makes around 465 HP, which run around 125 MPH in the 1320. I've dyno tested other peoples 302 restoration builds with headers and If I remember right it was 330-340 HP, now a well done rebuild could easily go 356 in my opinion STP. They never made 430 STP HP stock with headers. I did a nice factory build on a 1970 LT1 it made 395 HP STP and I think it peaked @ 6000 RPM.
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Re: GMs HP RATINGS

Post by vortecpro » Sun Oct 29, 2017 10:08 am

Oct 29 I watched Judson Masingill's 302 rebuild make 366-367 STP HP on a SF 902 with headers, the engine appeared to rebuilt to stock specs right down to the steel shim head gaskets. Peak HP was around 6000 RPM with a slight dip and held it to 6500 RPM, peak TQ was in the 330s.
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Re: GMs HP RATINGS

Post by vortecpro » Sun Oct 29, 2017 10:13 am

grandsport51 wrote:
Sun Oct 15, 2017 9:17 pm
[/list][/list]Year: 1969
Ford Boss 302 Vs. Chevy DZ 302
The history of the Trans-Am series is well documented. Unfortunately, the actual performance, or at least the real power output, of Chevy’s and Ford’s sub-5.0L street motors is somewhat less so. It seems that every article ever written about either the Boss 302 or the DZ 302 always mentions the same thing: Though originally rated at 290 hp, these 302s made as much as 400 hp. Checking out the spec box, we see that the DZ 302 was essentially a 302ci version of the 365hp 327, sharing the 11.0:1 compression, Fuelie heads, and even the Duntov 30-30 cam. Also present were the aluminum high-rise intake and Holley 780-cfm carb. As impressive as the specs were on the Chevy 302, Ford’s Boss 302 stepped up things with a pair of production four-barrel Cleveland cylinder heads that flowed as well as a fully ported set of Chevy race heads of the period. Compared with the Chevy, the Boss 302 was down slightly in compression (10.5:1 versus 11.0:1) and down in cam duration at 0.050 (228 degrees versus 254 degrees) but up in valve lift (0.514 versus 0.485). Both shared impressive induction systems, but the Boss 302 heads allowed it to not only overcome the deficit in compression and cam timing but also actually outperform the Chevy 302.

Our pair of 302ci small-blocks was run at Westech on the Superflow 902 in the same configuration, meaning no accessories, an electric water pump, and 1 3/4-inch, long-tube headers. Both motors were run with the same 750 Holley Street HP-series carburetor used previously on the 327 and 289. Naturally, both motors were subjected to timing sweeps as well.

First on the pump was the Chevy DZ 302. Rated at 290 hp, the DZ 302 pumped out 356 hp at 6,700 rpm and 333 lb-ft at 4,400 rpm. Where the Boss 302 never reached 325 lb-ft of torque production, the Chevy exceeded 325 lb-ft from 4,000 rpm to 5,200 rpm. The Chevy was certainly the king of the midrange.

Much has been written about the huge ports and valves used on the Boss 302, but the little Boss actually produced more torque at 3,000 rpm than the smaller-port DZ motor. Most important to Ford fans, the Boss 302 produced more ultimate power than the Chevy with peak numbers of 372 hp at 6,800 rpm. The peak torque of 324 lb-ft offered by the Boss was down compared with the DZ, but from 5,800 rpm to 7,000 rpm (and beyond), the Boss was the boss.

Specs At A Glance
&nbsp ’69 DZ 302 ’69 Boss 302
Displacement 302 ci 302 ci
Rated output, horsepower 290 hp at 5,800 290 hp at 5,800
Rated output, torque 290 lb-ft at 4,200 290 lb-ft at 4,300
Bore/stroke 4.0/3.00 4.0/3.00
Compression 11.0:1 10.5:1
2/4 bolt block 4 4
Crank (cast or forged) Forged Forged
Rod length 5.7 5.15
Forged rod Forged Forged
Rod ratio 1.753:1 1.716:1
Head casting No. 186 C9ZE-A
Chamber volume 61 to 64 cc 61 to 64 cc
Valve sizes 2.02/1.60 2.23/1.71
Peak flow rates (intake/exhaust) 210/146 274/176
Screw-in studs Yes Yes
Guideplates Yes Yes
Cam hydraulic/solid Solid Solid
Cam lift (gross) 0.485 0.514
Cam duration (0.050) 254 228
Cam lobe separation 114 114
Intake manifold Dual-plane Dual-plane
Aluminum/iron Aluminum Aluminum
Carb Holley 4150 4V Holley 4150 4V
Carb rating 780 cfm 780 cfm
Tested output, horsepower 356 hp at 6,700 372 hp at 6,800
Tested output, torque 333 lb-ft at 4,400 325 lb-ft at 4,200
Thanks for the great information!
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Re: GMs HP RATINGS

Post by DaveMcLain » Sun Oct 29, 2017 10:27 am

I never believed some of their ratings in the other direction 375HP 327, yeah right.

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Re: GMs HP RATINGS

Post by plovett » Sun Oct 29, 2017 11:02 am

430 hp stock 302? Nope. That is just silly.

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Re: GMs HP RATINGS

Post by Walter R. Malik » Sun Oct 29, 2017 11:13 am

NHRA "stocker" rules are not anywhere near resembling "STOCK".
http://www.rmcompetition.com
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Re: GMs HP RATINGS

Post by swampbuggy » Sun Oct 29, 2017 11:39 am

Thats for sure Walter.

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Re: GMs HP RATINGS

Post by pdq67 » Sun Oct 29, 2017 9:05 pm

The little Z-28 engine is like the big L-88 in a way.

Slap a set of headers on an L-88 and you might make upwards to 540 hp!

Then look at the, "stillborn", LS-7, 454!! Upwards to 600 hp!! Heck, wasn't the LS-6 rated at 450 and 460 hp back then?

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Re: GMs HP RATINGS

Post by cuisinartvette » Mon Oct 30, 2017 12:01 pm

Id tend to believe the lower #s posted. Anybody driven a stock 302 or LT-1 back then?
They certainly werent any kind of powerhouse for sure!

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Re: GMs HP RATINGS

Post by novadude » Mon Oct 30, 2017 12:24 pm

cuisinartvette wrote:
Mon Oct 30, 2017 12:01 pm
Id tend to believe the lower #s posted. Anybody driven a stock 302 or LT-1 back then?
They certainly werent any kind of powerhouse for sure!
Many of these musclecars always seem to be faster in people's memories than in reality.

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Re: GMs HP RATINGS

Post by MikeB » Mon Oct 30, 2017 12:47 pm

There's a story that Bud Moore was hired by Ford to test a Chevy 302 to see what Ford was up against. Moore reportedly said the Chevy made nearly 500 HP with the "off road" cam and 2x4 bbls on the cross ram manifold. But there are others who say it was closer to 450 hp, and revving the engine past 6800-7000 didn't do any good due to flow limitations of the heads. Gotta wonder what a 302 would rev to and dyno at these days with modern heads.

First Design Off-Road cam, P/N 3927140
Casting #3927141
Intake 257 duration @ .050" (333 advertised)
Exh. 269 duration @ .050" (346 advertised)
Lift: .493" intake, .512" exhaust
Intake Max lift @ 108 deg. ATDC
Exhaust Max lift @ 116 deg. BTDC

2nd Design Off-Road cam, P/N 3965754
Casting #3965751
Intake 248 duration (324 advertised)
Exh. 267 duration (334 advertised)
Lift: .512" intake, .535" exhaust

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Re: GMs HP RATINGS

Post by MikeB » Mon Oct 30, 2017 12:55 pm

cuisinartvette wrote:
Mon Oct 30, 2017 12:01 pm
Id tend to believe the lower #s posted. Anybody driven a stock 302 or LT-1 back then?
They certainly werent any kind of powerhouse for sure!
Those engines also had a steetable 30-30 cam, cast iron exhaust manifolds, and full exhaust system with mufflers.

I never drove a car with the LT1 or 302, but a friend of mine had a 66 Nova with the L79 350hp/327. As I recall it was identical to the LT1 except for the smaller hydraulic cam. It was very fast for its time, especially in the light Nova with (probably) a 3.70 axle.

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Re: GMs HP RATINGS

Post by Stan Weiss » Mon Oct 30, 2017 1:45 pm

Some Chevy cams from back in the day.

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Re: GMs HP RATINGS

Post by DaveMcLain » Mon Oct 30, 2017 2:13 pm

About a year ago we did some machine work for a guy who was rebuilding a Chevy 302 for a Camaro he was restoring. As far as I could tell the engine appeared to be mostly all original. His engine had the full floating piston pins in rods with plated bores that were totally worn out.

I plotted the cam which did have a few lobes that were bad and I got 256 at .050 on the intake with 254 on the exhaust on a 114.5 lobe sep for 26.6 degrees of overlap at .050. .482, .486 lift. I think that cam would have been very lumpy in a 302 with moderate compression. I wonder if that cam was actually the "stock" cam? The design has very long lash ramps too with a really long constant velocity ramp on both the opening and closing sides of the lobe. Setting the lash at .030 would put you right near the top of that ramp so I think that's probably the correct setting.

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Re: GMs HP RATINGS

Post by wwmtlineman » Mon Oct 30, 2017 2:18 pm

Our D/S 68 Camaro blueprinted to NHRA specs back in 1980 with RHS stocker heads made around 425 by the computer and the rules then were a lot tighter then they are now, factory pistons etc. It was interesting to see what a present day engine made plus I'm no pro engine builder either

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