DZ302; How much real horsepower???? - Team Camaro Tech
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post #1 of 34 (permalink) Old May 10th, 00, 12:36 AM Thread Starter
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I've on my second Z28 and both were incredibly fast but mostly top end power... we have all heard how Chevy under rated these engines as to torque and H.P. but has anyone actually run one on a dyno and know what they put out in STOCK form?????? Im talking about the way they were produced, not tweeked..

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post #2 of 34 (permalink) Old May 10th, 00, 08:04 AM
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From the people that should really know, the Real Horspower is estimated to be around 375 to 380. The SCCA camaros with some mods pushed over 500HP.
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post #3 of 34 (permalink) Old May 11th, 00, 06:17 PM
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If you have any old quarter mile speeds for Z/28's try the horsepower calculator for quarter mile speeds in mph. You need the weight of the car which is usually 3200lbs, plus driver weight. I think the mph method is more accurate, as the ET method requires a good launch, which most test Camaros had problems with.
The 327 Corvette with identical Cam and heads was rated at 360 hp. That's 1.1009 hp per cubic inch. If the 302 made the same hp per cubic inch it would make 304.178 hp.
I would think the 302 would be capable of making a little more hp per cube as it has proportionaly larger valves per cube. So, either the Corvette engine is over rated, or the 302 was closer to 320 hp on a good day.
http://sura1.jlab.org/~grippo/auto_noframe.html AUTO CALCULATOR PROGRAMS BY BOWLING
The speed calculator program at the bottom of the page shows with a 3400 lb car, if it went 107mph, it would have 325hp.
David

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[This message has been edited by davidpozzi (edited 05-11-2000).]

[This message has been edited by davidpozzi (edited 05-11-2000).]
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post #4 of 34 (permalink) Old May 12th, 00, 12:06 AM
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Well,

I can tell you from real-life experiences that a Z-28 in the quarter in 1969 would ourun both a 396/325 and a 396/350. It wouldn't however outrun a 396/375. NHRA factored the 1968 396/375 engine UP to a 390 horse reading back in 1968 to adjust for what they felt the motor was actually producing. To me, this pretty much confirms that the 302 had to be in the 375-380 area because the 396/325 and 396/350 ratings were thought to have been pretty accurate.

These of course were gross HP ratings at the flywheel.

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post #5 of 34 (permalink) Old May 12th, 00, 03:02 PM
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If you say the 302 was 375 hp, what was the 360 hp 327 from the Corvette? 400hp?
It looks like if the factory stock 302 were 375 hp it would hit 112mph at the end of the quarter, according to the calculator on the web page I posted. That's with a 3400 lb Camaro with driver. I'd have to go back and look some old quarter mile tests for the Z/28 and see what they turned in a quarter mile.

I think the web calculator calcs the actual net? engine horsepower that an engine would have to make to push a car to the given mph. So it would have to be an installed net horsepower number with accesories and stock exhaust system on it.
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post #6 of 34 (permalink) Old May 12th, 00, 04:51 PM
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OK. Here's more proof. Back in April 69, Popular Hot Rodding track tested what they called Chevy's Big Three. A 396/375 Camaro with street tires and a 3.73 rear end ratio managed a 14.60 at 98.90 MPH (weight was 3460 lbs.). The car of course was traction limited due to the street tires.

The second car tested was a 1969 Z-28. Best time here with street tires and closed exhaust was 14.74 at 95.78 (3.73 gears). It was also mentioned that with 4.88 gears installed that the Z-28 would turn 13.20 at 107MPH (headers and slicks here).

The third car tested was a 350HP 396 Chevy II. This car ran 15.15 @ 94.33.

Case in point here is that the 302 was quicker than the factory rated Chevy II 350HP 396 but slower than the factory rated 375HP 396 camaro. This goes back to my original point. The ACTUAL track times do NOT reflect accurately the HP ratings on the motors because of the traction limitations the cars had back during the time the cars were actually tested.

So I stand by my original statement that the 302 had approximately 370-380HP and these aforementioned road tests prove it. As far as the web calculator goes, I have never seen one go down the quarter mile yet so I can't make any statements as to whether it is accurate or not!!!



[This message has been edited by sr71bb (edited 05-12-2000).]
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post #7 of 34 (permalink) Old May 12th, 00, 05:57 PM Thread Starter
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My first z was a 68... it was bone stock....I remember my best 1/4 times were 14.3 at 103mph and that was using just the first 3 gears never got into 4th... had 3:73 this was back in 1973 and was on f70x15 polyglas tires and headers undone.... the only car that gave me a run heads up was a boss 302 mustang......the reason I asked the question in the first place was I wanted some reference point for the rebuild I just completed on my 69 302... I uesd the orig block and 202 heads Z intake and 780 holly but built it to a 383 it dynos at 410 lbs torque and 362 hp at 5200 but this is with a 9.4 to 1 comp ratio seat of the pant this is much faster... I just wish I had of run the original engine so I knew my starting point... Thanks for the input
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post #8 of 34 (permalink) Old May 14th, 00, 07:23 AM
 
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Zman torque is what does all the work and the seat of the pants feeling you get is from 410 ft. lbs. the 383 is producing.
There is no way the 302 came close to making this kind of torque. One other point is that those polyglass tires of yesteryear don't
come close to todays tires. The dyno figures say that the 383 should make one nice cruzin motor.
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post #9 of 34 (permalink) Old May 14th, 00, 03:42 PM
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69-ZMAN,
The formula is supposed to be best when using speed, less accurate for ET as it's more dependant on off the line traction.
It's interesting that using your mph of 103 and a car weight of 3400lbs weight (including driver) the calculator came up with 290hp!
They don't say, but I take it that the hp is what the engine is actually making in the car. While driving the fan, waterpump, and other accesories, breathing thru the stock exhaust manifolds, muffler, and stock ignition timing and curve.

SR-71BB,
In the times you quoted, what mods are allowed?
Open exhaust? Headers? Can they select thru a box of stock rocker arms to get the highest ratio? Is the camshaft stock or can they run a special "cheater" grind to get more power?
I'm thinking NHRA allows enough mods of that kind that any car running under those rules is not really "stock" anymore. It's really blueprinted under the rules and has many select fitted parts in it to take advantage of the rules. So you are really seeing what the cars POTENTIAL is. Not what they might have performed like off the showroom floor.

Years ago (too many) I street raced a couple of stock 302 Camaros, I had a 67 RS 327/275 with only an ignition re curve, Saginaw 4 speed and 3.08 gears. Our cars had the California smog pump on em. My 327 ran fairly close to them thru the gears. I got left a little off the line, but would hold on pretty good from there. I'd think if those 302's really had a hundred horsepower more than me I'd have gotten left in the dust really bad!

Anyway, I think the 302 has the highest hp per cube potential of almost any engine out there. So I'm not suprised NHRA factored it up.
David


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post #10 of 34 (permalink) Old May 15th, 00, 03:37 AM
 
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I have a friend that put his car on a dynojet chassis dyno. It is a 69z with a m21. At the time he had it on the dyno it was all stock as far as the long block but he did put on a performer rpm intake and a 750 dbl pumper ( He has since put it back to original ). The car made 245 rwhp and most dynojets a a little optimistic. So if you figure in drivetrain loss that puts you in the neighborhood of the factory rating. If you would like to see the car on the dyno I beleive theres a pic on the shops web site its called pauls high performance in jackson, Mi . I think the link is www.paulshp.com . Its the fathom green z in the pic gallery.

steve

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post #11 of 34 (permalink) Old May 15th, 00, 04:16 AM
 
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I had a 68 Z and it ran a 13.99 @ 105 bone stock (smog control). It was a RS, custom interior, M-22 rock crusher, and 4.56 gears and my 210 lbs.

After smog pump removal (my memory tells me someone stole it!), it ran a 13.71 @ 108.

As a note. I ordered 4.56s and the car came in with 3.73s. The dealer ordered a Z with 4.56s and exchanged the rear axle assembly rather that just the pumpkin. (lotta negotiating) The Z with 3.73s and 4.56s (or 4.88s) was a HUGE difference. The 302 needed a lot of gear.
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post #12 of 34 (permalink) Old May 15th, 00, 10:35 AM
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Thanks guys, It's interesting to see that the MPH figures are pretty close.
I think the couple of Z cars I raced were not well tuned up or something. I found an old time slip and my 67 turned 15.12 at 95 mph back around 1969! I had the 7.35 X 14 Uniroyal Laredo tires on it. Definitely not "tiger paw" grip.

I later put in a 350 LTI with 800 holley, and 4.56 gears. Still couldn't get off the line but turned 12.88 at 114mph. I had wider tires but the car was set up for handling.
David

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post #13 of 34 (permalink) Old May 17th, 00, 06:46 PM
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Wasnt the Z28 for Transam racing where it was constantly reving 8 grand. I think the 302 would be best for road racing than 1/4 mile. Same stuff I am going through with my 69 Z. I want to put some cubes in it, but then it wont be the 69 Z that it is.
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post #14 of 34 (permalink) Old Jun 15th, 00, 06:00 PM
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I have a copy of an acuall dyno on the 302 built for SCCA competition.It put out a max HP of 464 HP and 260 FPT Peak horspower was a 7400 RPM. I wish they would have put the 302 hemi motor into production.Althogh 2 are still known to exist dyno figures are still to be seen. As for the 302 in stock form i agree with the 325 HP guess. My 69 Z/28 went a 13.74 pass with the 140 cam and headers on dry rotted goodyear eagles and 410 gears with the last owner driving. The car has only 34,000 documented miles on it to this day. as for the ZL1 the #23 car dynod at 565 HP all original rebuilt or nos parts even with the stock exhaust manifolds. That motor was for sale at Heartbeat city for $20,000.
post #15 of 34 (permalink) Old Jun 15th, 00, 08:14 PM
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Jeremiah,
Take another look at your dyno chart, the torque scale is on the left side not the right.

The 302 was done to meet the SCCA rules. Not because it was some ideal displacement for a small block chevy.

It turns out that for hp per cubic inch it IS pretty much an ideal size. Compared to the rest of the small block family. But GM could have destroked it to a smaller displacement and gotten more hp per cubic inch but less overall HP.

Torque is really nice in a road race car. You need torque to pull the car off the corners. Many road courses are like a series of drag races from corner to corner.

The more difference in speeds on a road course the more gears you need to keep the engine in it's operating range. Or the engine will drop too many rpm's between shifts.

So it depends on your point of view if the 302 is a desireable engine. In terms of hp per cube it is. Many road race classes allow a 302 at a set weight, or a 350 but with a weight addition. If the 350 makes less hp per cube and the weight has to be not only accelerated but decelerated lap after lap most racers go with the 302.
Also more wheelspin is encountered with the 350 option and rear tire life suffers.

For a guy like you or me, we just want the thing to jump when we punch it. That's where torque is king and more cubes does the trick. We don't get penalized for having a bigger engine. So we use a bigger engine with usually the same valve size of the 302 and we get the hp and torque at a lower rpm.
David

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