Dyno results w/ G-W heads

I just received the dyno tests on my engine. I thought you might be interested. The engine is a 302 A 4, with a forged crank, Carillo rods (5.665" long), dry-sump oiling system, Gurney-Weslake cylinder heads, TWM throttle bodies, JE pistons (10:1), and a C. R. Axtel roller camshaft (244º @ .050, .650 lift). The results are 377 lbs/ft @ 4600, and 453 hp @ 6800.

My engine builder (CMW Motorsports) assures me there is still more power to be made with the current setup. Once the engine is installed, we plan to put the car on the chassis dyno, and finish the tune-up with the regular headers in place. The dyno work was done with dyno headers, and not the 180º headers that go with the car.

Although it is not near as impressive as some engines that have been discussed on this forum, it’s not too bad for a set of cylinder heads that are more than 35 years old.

 

Why didn't you stroke it? Since you bought a forged crank, carrillo rods and forged pistons, You could have made a nice 331.

The rod ratio isn't as good, but yours seems pretty excessive.

I'm just curious, was it racing class rules? Did you get a great deal on the long rod 302?

Also, how tall are your stacks?

I think one place that you are probably leaving power on the table is your compression ratio. If you run a large enough cam, your dynamic compression ratio is lowered signifigantly. That will let you run 11-1 or more on street gas.

I assume that you are registering it as a 60's car, so you won't have to smog it. You can run any cam you want, so take advantage of it with your compresion.

 

[Mark Worthington]

That sounds like a great setup and those are some awesome numbers for a 302. I bet you'll get a little more with the crossover exhaust.

I'd love to see a comparison of how the G/W heads flow compared to modern heads like AFR 185/205s or Vic Jrs. Did you happen to get them onto a flow bench before they were installed?

 

Built2rev:

“Different strokes for different folks.” When I started assembling parts for the engine, many years ago, I made the decision I wanted to build a long rod 302. I guess I had read one too many Smoky Yunick articles. In any event, that’s what I wanted and that’s what I did, and the long rod combination doesn’t appear to have hurt anything. As it turns out, I probably have more horsepower than I will ever use.

As to using a larger cam, and increased compression, I was more concerned with making this is a streetable combination. Had I wanted to push it to the absolute limit, I am sure bigger numbers would have been available. However, I am not sure I would have enjoyed driving it on street. (I know of 1 G-W 302 that produced 540 horsepower @7000 rpm, with a flat tappet cam, and Webber carburetors. It idled at about 1200 rpm, and had a compression ratio somewhere north of 12:1. It definitely was not for the street.)

It sounds as though you’re going to build a 331 motor. If you’re interested, I do have an semifinished SVO crankshaft, that can be finished ground to a 3.3 inch stroke.


Mark:

I had the heads on the flow bench, some years ago. C.R. Axtel did the work, and was more concerned with making sure the heads were balanced from port to port, then he was with overall numbers. The heads had been reworked extensively when I got them, so no additional porting, other than very minor touch up, was done.

I don’t know how these heads would compare with others currently on the market. I have to believe that the current generation of cylinder heads would be superior to those on my motor. In any event, when we do the final tuneup, on the chassis dyno, I will post an update.

Michael

 

[Mark Worthington]

Michael, good luck with the final tune. Sounds like you have a great street motor. I am also a believer in good rod ratios (even though I own a stroker). Yeah, it seems like most of the G-W heads out there have been extensively worked, often times with large increases in port volume. I'd be very interested if you could post a dyno chartafter you complete your tune.