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302 Chevy True HP!

40K views 25 replies 17 participants last post by  FiefSS 
#1 ·
I am kinda frustrated to see no info on what I would consider the greatest SB Chevy ever. The 302 in my opinion was a high reving, monster that doesn't get the respect it deserves. To the best of my knowledge Chevy never even revealed the true Horespower figures of this car. I heard that in the late 60's many magazines dynoed the motor, with varying results. What is the true HP, and Torque figures of a stock 302 Chevy, and how much horsepower does a Crossram setup add. I would love to know, cause I have a 302 in the garage waiting to be awaked, and I want to know what its capable of. thx
 
#3 ·
I loved the way GM has understated their horsepower ratings! Not only was the 302 "290 HP" but another comes to mind. 86 Buick Grand National, 3.8L, intercooled turbo, 230 HP, sure it was. I never dyno'd mine, but it was impressive with eprom change, head work, better air induction, upgraded exhaust. I'd be willing to bet on closer to 400 HP to the pavement.
 
#5 ·
I remember that dyno test too. Seems like it was HOT ROD that did it. They did a 302 Chevy and a Boss 302. If memory serves they both put out right at 325 HP. I can't remember the torque reading. ( these were brand new "crate" motors )
Phil
================================================
Originally posted by FiefSS:
I heard that in the late 60's many magazines dynoed the motor, with varying results. What is the true HP, and Torque figures of a stock 302 Chevy,

[ July 16, 2002: Message edited by: Customcab ]</p>
 
#6 ·
yeah i have this mustang book and it said that with no air cleaner or accessories and open headers a stock boss 302 made just under 400 horses. I dont think 485 is very accurate, it sounds pretty unrealistic for a 302 cubic inch small block. Think about it, in those days of flat tappet lifters that thing would be no street engine at all and probably would get about 5 mpg. Even fuel injected roller cam 5.0s that make 485 horsepower aren't streetable. 302s are great high reving engines though.
 
#7 ·
uh..this is a chevy we're talkin about aint it?

get the new HRM and it will tell you all you need to know. on cover:"20 (or whatever) new ways to build a sbc." it's either a 283 block/327 crank or the other way around. go to hotrod.com and find the mighty mouse article, it also yaks about a 302 claiming like 330 HP with normal asperation and 550 with a vortex blower on it. as i have never had one and never expect to see one i only used one eye when i read the article. ps. get a subscription to HRM it's only like $12/yr and it would be the best 12 bucks you ever spent, even tho they have alot of crap in there it usually has lots of good POOP!
 
#8 ·
oh by the way, some other of that good POOP i was talkin bout was the carb test they did a few months back: i.e. the cross ram intake is a pile of the aforementioned POOP! throw it away! getta air gap or something new!!! single quad intakes or tunnel rams destroy those old junkers. even the sacred original torquers suck compared to the new intakes.
 
#9 ·
thx everyoen for replying, when the 302 runs again i guess i will get it dynoed or sumptin. It aint stock though so thats why i wanted to know. Racing Cam, edelbrock tarantuala intake, not stock heads, and headers all from the 70's. I will post what the dyno results are whenever i get it done. I will keep searching, i wish i could just get the answer from chevy. Did they never reveal the true hp? Im sure it wouldnt hurt any now if they did.
thx, again
 
#10 ·
I don't know the HP but 335 sounds believeable. I remember the first one iI saw. In late 1967 I was running a 66 442, rated 350 HP in G stock. I had taken the trophy for 7 straight weeks, wiping out all comers. A guy rolled in with a new Z28, and I thought, "this is a joke, thinking he car run with my 400 with a small block" Well, he cleaned my clock, wasn't even close. I decided then that it was time to start cheating, took a lot of money to finally out run that stock Z28
Jack
 
#11 ·
hi, i have to correct my stupidity on a 302, to a certain degree anyway, i still don't know much other than a 302 has a 4 inch bore so i think that makes it a 283 bored out .125 inches, since if you bore out a 283 .125 it comes out to 302 cid. A 283 with a large journal 327 crank is a 307. also the article on "carbs" was really about intakes, like you couldnt figure that one out. an old tarantula? should rock! i haven't even heard that name in 20 years! in that 25 ways to build a sbc, aug.'02 HRM, the most interesting to me, other than the "norm" 383, was what you could do with an old 283: 475 HP at 8000 rpm! (w/vortec heads)
 
#12 ·
The 302 made from 67 to 69 that was in the Z28 had a 4 inch bore ( same as a 350 ) and a 3 inch stroke ( same as a 283 ) . The 67 had small crank journals like the 283 . The 68 and 69 had the large journals like the 350. They were a 4 bolt mains and came balanced and blue printed. The Hot Rod article they are speaking about above I have some were and I will try and find it but I believe HR said something like 425 HP. That is from memory and it ain't what it used to be.
 
#13 ·
My high school friend, Paul Hubble, bought the first Z28 sold in California. The engine was a destroked 327. Simple, block and pistons 327, rods and crank, 283. This allowed the highest possible lift cam Chevy could install. 8,000 RPM with no valve float. Fast car. Paul traded it in on a '70 LS6 Chevelle, that he still has. I say build it, dyno it and obtain the true horsepower.
My guess would have it at 325 or better. Fastgo
 
#15 ·
Blah, Blah, Blah. My Goodness. Chevy under rated this monster for sure but one of the jocks in school had his Mommy buy him one brand new, factory. I remember it was 325 horse 350 ft lbs torque. That was book specs. We both know it was much different real time. I do know that in the Z28 Camero that sucker would lift a front wheel from a dead stop, go sideways in third gear and just loved 6,000 rpm. I guess the only way to know for sure is to wake him up and dyno this treasure yourself. I agree with you in the fact that this beast was not recognized for the weapon it was. They weren't known for their endurance and only ran a short time before a major rebuild but wow, whatta ride. I envy you. If you ever do find out the actual specs, please share them with us.
 
#17 ·
Originally posted by Olds:
<strong>Blah, Blah, Blah. My Goodness. Chevy under rated this monster for sure but one of the jocks in school had his Mommy buy him one brand new, factory. I remember it was 325 horse 350 ft lbs torque. That was book specs. We both know it was much different real time. I do know that in the Z28 Camero that sucker would lift a front wheel from a dead stop, go sideways in third gear and just loved 6,000 rpm. I guess the only way to know for sure is to wake him up and dyno this treasure yourself. I agree with you in the fact that this beast was not recognized for the weapon it was. They weren't known for their endurance and only ran a short time before a major rebuild but wow, whatta ride. I envy you. If you ever do find out the actual specs, please share them with us.</strong><hr></blockquote>
 
#19 ·
to the gentelman who wanted to know the true h.p. of the best small block ever built.the 302 chevy the following info. was taken from the
book camaro untold secrets by wayne d. guinn
the following test were done by the engineering lab at G M test 1: single 4 bbl 800
cfm holly carb on ported z28 intake 441.5hp @
7400 rpm
test 2: 2x4 cross ram intake two 600 cfm hollys 467 hp @ 7400 rpm with a gain of 25ft.-lb from 5000-6500 rpm
test 3:Kinsler 8 tube F.I. 470.1 h.p. @ 7400 rpm
I've also read an article that I think was written
by Mr.Guinn that stated that the Penske engines made 486 h.p. @ 7800 rpm I don't
recall the torque #'s but the test lab had the figures around 340-375 lb-ft. one foot note was the fact that the heads used were Traco prepared heads milled .050 and they used a service cam w/ .527/.492 lift and headers on the dyno factory c.r. was 11.0-1 with the heads
milled .050 it increased c.r. somewhat I am also building a 302 for my z28 w/ cross ram
that will be dynoed some time in the spring hope the info helps I'll keep you posted. I'ts a great book. you should pick it up. the isbn# is
0879385278
 
#20 ·
Originally posted by FiefSS:
[QB]I am kinda frustrated to see no info on what I would consider the greatest SB Chevy ever. The 302 in my opinion was a high reving, monster that doesn't get the respect it deserves. What is the true HP, and Torque figures of a stock 302 Chevy, and how much horsepower does a Crossram setup add.

Hate to be the odd man out here. I owned 2 Z28's...a 67 that was stolen and a 69 that replaced it. Stock 302 Z28's made 330 to 350 horsepower. End of story.

That was with 11 to 1 and good premium fuel. You can not ger away with that today. All the BIG numbers stated above may be true BUT not stock. Those numbers come from highly modiflied engines that were non streetable.

The reason that GM dropped the 302 is they were getting their doors blown off on the street. The 70 Camaro was heavier and needed more power. Which car would you really rather have to street race with....... a 427 Camaro or a 302 Z28 ?
 
#21 ·
I'll agree with Deuce on this, the factory 302, spit out around 350 Horsepower, the same engine in race tune, IE worked over heads, crossram and offroad cam, would spit out around 450 horsepower IF the tune up was right.
Some dynos are more forgiving than others, so you can't really say exactly how much an engine would spit out, but say 330-350 horse for a garden variety, factory 302.
I have dynoed very small engines that will shock you, how about 600 horses from a 310 cubic inch V-6? Sounded like a heard of killer bumblebees.
 
#23 ·
I see a single plane intake, a Holley, straight plug heads and a set of old M/T valve covers.

Let us pretend that yours is all pumped up, which by the way will make it less streetable. It is 460 HP. That's 1 and 1/2 horsepower per cubic inch. That's a big number for a single 4 barrel 302. A stock 454 LS6 makes 530 to 550 in stock form.

See you in the mirror.....

Now thats FUN.

You are to be commended for mastering Photo Posting 101. A lot of the people here cannot.

IF I was you I would post the photo in the BIO section where it will post beside your name. To me it give a little creditablity to the post or opinion.

By the way, nice Camaro......hope you much happiness with it........Why is there a For Sale in the window?? :D
 
#25 ·
I have seen some well tuned DZ 302's run at the pure stock muscle car drags with a totally stock setup, 4 speed, 4.11's and shifting near 8000 rpm and only runnin' 14.50's. to me that translates to about 260 net horsepower with stock manifolds.
headers are a different story. with the stock camel humps (202 160) 12:1 compression and a roudy solid lifter bumpstick, they could make about 430 ponies @7500 rpm in race trim. the crossram is an upstairs engine speed intake that will wake up a race engine. they pushed the badboy to over 500 ponies. however if you plan on running her on the street, get ready to work that clutch leg out.

Hope that helps out. <img src="graemlins/pimp.gif" border="0" alt="[pimp]" />
 
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