Don Terrill’s Speed-Talk

A friend has a complete engine shop with dyno...A just did a stock 69 302 rated at 290 hp at 5000 or so..It made 430. What have you found with others ??? Oldhead

I didnt know it would turn that many RPM's
reed

[/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

I would have the dyno checked......

One of the magazines did a test of late 60s performance engines built as close to factory spec as possible. I don't remember if they tested a DZ302 but they did test a Boss 302 and it produced over 400hp as well, at some ludicrous RPM.

290 @ 5000 was a real figure, just not the PEAK figure.

Most of the other engines were way under, incidentally.

Boss heads on a 302 are just starting to scratch the surface of getting into a useful port velocity range @ 5000 rpm!
Now If this dyno test showed 430 hp at 5000 you have useless data there and a paper hero in regards to the dyno print out sheet!

mag2555 wrote: ↑Mon Oct 16, 2017 6:25 am
Now If this dyno test showed 430 hp at 5000 you have useless data there and a paper hero in regards to the dyno print out sheet!

He didn't say that.

JR

Did you dyno SAE or DIN? Although they were a bit "creative" with numbers back then I don't think they based the numbers off what conditions we usually dyno today.

John Ross wrote: ↑Mon Oct 16, 2017 6:34 am

mag2555 wrote: ↑Mon Oct 16, 2017 6:25 am
Now If this dyno test showed 430 hp at 5000 you have useless data there and a paper hero in regards to the dyno print out sheet!

He didn't say that.

JR

JOHN, YOU ARE VERY INTELLIGENT PERSON,AND I THANK YOU.......SO MANY TIMES THE GUYS ON HERE "MISUNDERSTAND WHAT I TYPE.I did not say 430 at 5000....its not them, I am 81 yo. and type poorly. (I had to stop school at the 8 grade)....I just called my friend, the 302 chev made 430 hp at 6700 hp. When he got his dyno he would test it, He found it stayed accurate, he checks it less often now.......He is a very honest man...THANK YOU FOR READING CORRECTLY Oldhead

The inference is made that it's not stock any more DONE BY STATING that the stock rating was 290 @5000 is what leads the reader to think that it's now making 430@ 5000.

I read "somewhere" that a BUNCH of the older engines had horsepower numbers that were way under actual output. Something about insurance companies.

Oldhead didnt you have a DZ302 new?
If so what did it run at what weight?

NO,Never had a 302.......I am a dumb oldman,But when my friend said 430 hp. Even I knew it certainly was not near 5000 Oldhead

I interpreted the original post as saying...that a stock 69 302 rated originally at 290 hp has been rebuilt to stock specs & puts out 430hp. If that is the correct interpretation of the post, I will be watching for the sun to come up from the west tomorrow......

In 1969, PHR magazine got hold of pony cars from showroom floors, yanked the engines, & dyno tested them to see if they made the advertised hp. So no tricked up factory test car with richer jets, faster timing curve, air cleaner lid inverted etc. What the buyer would be getting from the showroom floor. The results were published in the Feb 69 issue, & only one engine made the adv hp!

Adv hp real hp
Chev 350 290 240
Olds 350 325 280
Pontiac 350 325 255
Ford 351 290 210

Only the Chrysler 340 made the adv hp of 275 & in fact it made 20 hp more, 295 hp!!

I remember that issue of PHR and held onto it for a long time to refere to it , but with that said what we know now as to having the flow stock numbers in hand for all of these motors along with there Cam spec's and true compression all I can say is Mom Mopar was testing with just the water pump powered and not as installed in the vehicle !

I still have the 1971 Edelbrock catalog and in it they have reprints of Cam and Intake test out of PHR issues where they used a 350 Chevy and a 340 Mopar and they went about every thing they could to get these motors up to 500 hp, even as far as porting the heads and running there new street tunnel rams with two 4bbl Carbs on both ,and the in the end got pretty close with both of them, but the Chevy beat out the 340 at every step of the testing and in the end took out a rod bearing!