53 Engine Dyno Results

[Russ U.]

Dave Elie, the long-time owner of 1953 #276, upgraded his 53 Corvette for performance in a number of ways. Elie swapped out the original 235 block for a truck 261 block, which was a technique popularized by McGurk Engineering. Elie also had some head work done to improve air-flow.

53 #276 has over 300k miles on it, and the 261 block has maybe half of those miles. So I rebuilt the engine according to Dave Elie's specs. Dyno sheet appears below.

What do you guys think???

Russ
Early Corvette Website

[Clem Z.]

Re: 53 Engine Dyno Results

Dave Elie, the long-time owner of 1953 #276, upgraded his 53 Corvette for performance in a number of ways. Elie swapped out the original 235 block for a truck 261 block, which was a technique popularized by McGurk Engineering. Elie also had some head work done to improve air-flow.

53 #276 has over 300k miles on it, and the 261 block has maybe half of those miles. So I rebuilt the engine according to Dave Elie's specs. Dyno sheet appears below.

What do you guys think???

Russ
Early Corvette Website

interesting as i had a 261 block in my 53 chevy after blowing up the 216. i had dual carbs,homemade headers with duals,dual point conversion and a mcgurk cam. it ran good enough to blow off those new 1954 fords with the new OHV V-8. nothing sound nicer the a straight 6 with dual exhaust and chevy truck mufflers. the water temp 103 degrees seems pretty low as a engine is a heat pump i would think it would make more HP at a higher temp like 180/200

[Duke W.]

Re: 53 Engine Dyno Results

I've never seen any other test data for the six, and I assume this was a lab dyno test to what is essentially SAE gross standards.

Peak gross torque of one lb-ft per CID is typical for most naturally aspirated engines with relative high compression. What is the CR and what fuel was used?

The top of the 80 percent torque bandwidth is about 4800, but as is typical with the way most operators test, the bottom of the 80 percent bandwidth is indeterminate due to the start speed being too high. It should have been tested down to at least converter stall speed with is usually in the range of 1500-2000.

The peak power range extends beyond the maximum test speed. Unless 5000 is the recommended rev limit, the useable power bandwidth probably extends to at least 5500.

BSFC is very good, and the rich side can be down jetted to equal the lean side, which is not too lean to cause problems. My maximum A/F ratio recommendation at WOT is 13.5:1.

The coolant temperature is waaaaaaaaaaay too low, which cost power.

Overall it has a fairly flat torque curve with a broad and flat peak power range - exactly what is needed with Powerglide, and compared to the original 223/150 ratings, it's a substantial improvement. It should feel very strong and responsive in normal road driving conditions compared to the OE configuration.

Can you provide more details on the configuration - head work, flow data, CR, valve timing/camshaft?


Duke

[Russ U.]

Re: 53 Engine Dyno Results

Thanks for the info guys.

Interesting about the water temp. I wondered about that. My mechanic and the rebuilder did a bunch of separate tests changing the jets, so I have a bunch of dyno sheets. The water temp on all the other tests runs from 161 to 175 degrees, but with lower hp and torque numbers. I suspect the engine cooled before the last jet change, but the hp and torque numbers were up a fair amount in that test notwithstanding the low water temp. So they declared victory.

The rich and lean numbers are closer together on some of the other dyno runs, but the hp and torque numbers were still lower. My mechanic said that he and the rebuilder spent a lot of time playing with the jets, so I don't think there would be much enthusiasm for going back in to tinker.

I don't know the current CR or camshaft, so I will have to check on that. The dyno sheet says the timing is 2 degrees, but I will check that out also.

I met with the mechanic who installed the 261 block in the car for Dave Elie 45 years ago. He thinks the engine CR was 8.5 to 1 when he installed the engine. The exhaust outlets had been enlarged to mate better with the standard exhaust manifold. I don't know about other head changes.

The straigh 6's most redline at 5000. The original Corvette tachs did not have a redline. But the tachs only went up to 5000. Dave Elie's mechanic told me that the straight 6 would go quite a bit higher than 5000 however.

My 53 has a early 60s Corvette 4 speed with a 3:70 rear end.

Russ

[Clem Z.]

Re: 53 Engine Dyno Results

here is a book to read if you want to hop up 6 cylinder chevy and gmc engines. i have one here someplace. http://www.goldengatebookstore.com/r...73&affnr=-2610

[Russ U.]

Re: 53 Engine Dyno Results

Thanks Clem. I have not seen that book before. I am going to order it.

Hot Rod Magazine published a lengthy article on how McGurk souped up a 261 chevy truck block into a fire-breathing dragon. The magazine has plenty of information and dyno test runs using different configurations. An interesting read for Blue Flame Special fans, or for guys who own a car with a McGurk modification: McGurk Article

Russ

[Clem Z.]

Re: 53 Engine Dyno Results

my dual carb setup was a "edmunds" that use the hot wter from the engine for heat. you just ran the heater hose in one end of the manifold and out the other so i was able to use my homemade headers. i blew my 216 and the car was still under warranty and the service manager at the chevy store was a good friends dad so i got them to put in a 261 block under warranty.