DZ302 engine horsepower rating

[musclcar]

i know the DZ302 chevy engine shows 290 hp because i've seen numerous cars with this engine with the engine size decal on the air cleaner.but i remember somewhere reading that this engine was way underated in horsepower because of the feds.what is the actual horsepower these motors put out is it something like 400 hp or ?.i know you could ad on factory installed headers,cross-ram and the 493-512 mechanical cam from the dealer as options right. so does anyone know then actual factory flywheel horsepower i've got a bet going and hopefully i win thanks http://www.yenko.net/ubbthreads/images/graemlins/3gears.gif

[Jeff H]

I think the actual hp is around 325-350 hp. Same as the Boss 302 Mustang although they were rated at 290 as well.

[Mr. T]

Good post. I have thought about the "actual" horsepower for 69 Camaro's before. How about the other 69's, like the SS L48, L34, L35, L78, or even the COPO L72 or ZL1. What would be the actual horspower for these engines? I have heard many times that L72's and ZL1's were way underrated for hp.

Jeff, is that 325-350 hp for a stock DZ, or after the crossram and other dealer items have been added?

[Jeff H]

I've heard 325-350 from stock 302 engines. With some head work, 140 cam, crossram and headers Traco dyno'd it at 458 hp I think.

[musclcar]

is there any documentaion or any other info on these hp figures for the DZ302. i tried to explain this to a friend and he laughed into my face http://www.yenko.net/ubbthreads/images/graemlins/3gears.gif

[@wot]

i recently saw a dyno test on an l78 chevelle with 60-70,000 miles, all stock, and it pulled 331 horsepower at the rear wheels. if you consider a 25% loss through the drivetrain, it would gross at about 415HP. a fresh stock engine would do much better

[Stuart Adams]

Whatever the hp is, my Z never felt fast. Overrated IMO.

[@wot]

the feeling your looking for is torque. try a big block. your small block isn't coming to life untill you get above 4500 rpm, and is happier at 7,000.

[@wot]

just checked your profile. you know plenty about torque!

[JoeC]

NHRA "corrected" the factory HP rating on some cars. I think they rated the 302 at 380hp. You can look it up but you have to look up the old ratings because NHRA changed the ratings sometimes. One year they really hammered the rating on the 302 because it was winning too much.

[NCGuy68]

[ QUOTE ]
One year they really hammered the rating on the 302 because it was winning too much.

[/ QUOTE ]

Yep....the little small block that could out run the big blocks in "D" and "E" Stock Class way back when NHRA was for 'grass roots' guys and not "Pros" as is today. Same thing happened in the late 60s when NASCAR outlawed the Hemis. Said they made too much power and don't bring them back! Go tell Richard Petty that!

[Salvatore]

In 2004 NHRA rated the D and E Stock 302's at 305 H.P. Too much H.P. rating for there class because they had to run the low compression 351 fords with low factory ratings. Made the 302 fast but not always fast enough to win class. It is all about how NHRA rates the motors. Getting back to not feeling fast.....Mr. Adams is correct! ALL Z/28's need M20's and at least 4:10's to pull away from a traffic lite. Most all old magazines feel that the Z in factory form is 325-350 h.p.

[68TopStock]

My 302 with the crossram is totally stock, with std bore etc. It dyno'd at 359hp. If the xram is worth 25hp, (per factory) then mine would be 334 hp with a 4 bbl. I run an M20 with 5:38's. This year my best 60' time was 1.80 and e.t. 13.01.

Guys were running 302's in the early 70's at 11.00 flat in AHRA. Gene Dunlap had these times with his Harrell 302 GT racer. I calculated that my car had around 450hp when Fred had it, based on a weight of 3200 lbs, and times of 11.75 in the 1/4.

ps. I have only driven one other car that was as much fun to launch and shift, and that was Matt's DH proto #2. Neither feel "slow".

[Salvatore]

Ken, The 538's say it all with a 254 first gear! In the mid 70's when my friends, Pete and Ron set the G/MP national record they had a 280" motor with a 6:17 rear and a 3:00 first gear. (Nash 5 speed). Also had a 50lb. flywheel. Car weighed 3400lbs. Went 11:00 at 126. 1957 chevy 2 door wagon. My theory on the small blocks is start with the gears and a good http://www.yenko.net/ubbthreads/images/graemlins/burnout.gif http://www.yenko.net/ubbthreads/images/graemlins/3gears.gif motor will take care of itself. When I would ride in the 375 hp BB camaros they felt like rockets, but when I would run them with my 69 LT1 nova I was right at their door. Ben Wenzel goes 10.60's with a D/S 302 67 Z/28. My feelings Ken, is that your car was one of the most Super Cars at the reunion. Talk about history! You car is Day-1 and never changed. http://www.yenko.net/ubbthreads/images/graemlins/biggthumpup.gif

[68TopStock]

Thanks Sam. I've had a lot of help, especially from Dave Libby who told me the set-up that was used on the clutch and flywheel back in 1968. When I weighed the current 40lb Hayes flywheel and clutch set-up, it weighed 64 pounds.

The Wenzel's are quite a dedicated crew, I heard that Ben and Jerry MacNeish got to race each other at Indy last summer. That would have been some race to watch!

[Chevy454]

Ben Wenzel (http://www.dragracecentral.com/DRCPhoto.asp?ID=31400) http://www.yenko.net/ubbthreads/images/graemlins/3gears.gif