72 LT-1 Dyno Run

[Ken P.]

Was wondering if anyone else has Dynoed their LT-1.

Mine got 257HP @ 5700 RPM I limited them to 5700 is the only reason they didn't keep going. I'm sure it would have been higher because it was still building at 5700. So much for factory specs.

[Bob B.]

Re: 72 LT-1 Dyno Run

Ken,

Was it just your engine dynoed or was it where you run the rear wheels on the dyno? Rear wheel HP will be a lot less due to friction losses.

Just for fun, I am putting together a 350/370 LT-1 engine with a Corvette 2x4 setup on it. We dynoed the engine a couple of weeks ago without the air cleaner and it came out to 282 HP at 4,800 rpm. Amazingly, we put on the air cleaner with filter and it did 332 HP at 5,400! So, the right air flow makes a big difference.

The engine was perfect, as were the carbs, and my missing 38 HP was attributed to the less than ideal flow characteristics of the 2x4 intake manifold, but I am going to use it anyway just for looks.

Bob

[Duke W.]

Re: 72 LT-1 Dyno Run

What this a lab or chassis dyno test?

Is the data observed or corrected, and, if corrected, what convention was used?

There is what appears to be a torque curve, but the scales don't make any sense for either a lab or chassis dyno test.

On a Dynojet any decent 327 should be in the 270 lb-ft ballpark for peak torque regardless of power, and a 350 should be near 300, but in my experience, Mustang chassis dynos read 5-15 percent lower than Dynojets, and I don't recommend them. Dynojets give much more consistent readings, so SAE corrected data can be compared to other Dynojet tests from different times/places.

A dyno chart with no explanatory information about the test or the details of the engine configuration and test setup and correction factors is worthless for comparison to anything else because it totally lacks context.

Duke

[Clem Z.]

Re: 72 LT-1 Dyno Run

Ken,

Was it just your engine dynoed or was it where you run the rear wheels on the dyno? Rear wheel HP will be a lot less due to friction losses.

Just for fun, I am putting together a 350/370 LT-1 engine with a Corvette 2x4 setup on it. We dynoed the engine a couple of weeks ago without the air cleaner and it came out to 282 HP at 4,800 rpm. Amazingly, we put on the air cleaner with filter and it did 332 HP at 5,400! So, the right air flow makes a big difference.

The engine was perfect, as were the carbs, and my missing 38 HP was attributed to the less than ideal flow characteristics of the 2x4 intake manifold, but I am going to use it anyway just for looks.

Bob

you need something to "straighten" the air flow into the carbs to prevent turbulence around the carb air bleeds. that little screen around the carb on a L-88 was not there to keep out birds. it was there to straighten out the air flow when the L-88 was run without a air filter element.

[Ken P.]

Re: 72 LT-1 Dyno Run

This was with the engine in the car with everything hooked up and running rear wheels on the dyno. Engine is totally stock except: no A.I.R. and I put a Mallory distributor in.

[Steve B.]

Re: 72 LT-1 Dyno Run

Those are strong numbers for a stock 72LT1, putting out its net rating to the wheels.

[Jerome P.]

Re: 72 LT-1 Dyno Run

My '72 LT1 developed 271 ft. lbs @ 3900. I limited the test.

My 2003 developed 327 @ approx 4300. and 305 HP @ 6000

The Dyno used was a DYNOJET chassis dyno

[Don W.]

Re: 72 LT-1 Dyno Run

Here's the info for my '69 427/390HP rebuilt by prior owner with likely < 9.0:1 pistons.


2 dyno runs; 1st run to check baseline status, air/fuel mixture, etc. Carb primary jets and larger needle and seat changed; float level corrected by 1/4"

Results:
dyno used to reset idle mixture
dyno used to reset timing from 4 degrees to 16 degrees BTDC; vette mechanic reports '80's engine rebuild likely had pistons changed to ~ 8 - 8.5:1 (due to 16 BTDC)

• + 16 HP from 1st run to 221 rear wheel HP
• + 17 ft-lb of torque to 310 ft lbs torque at rear wheels

fuel economy test shows 14.43 mpg highway

[Duke W.]

Re: 72 LT-1 Dyno Run

Dyno type?

Correction?

There's no way to rationally compare your data with any other data unless some basic context information is included.

Posting the graph will usually contain the necessary context informtion, but not always.

Duke

[Jerome P.]

Re: 72 LT-1 Dyno Run

Ken, Is a Mustang Dyno a bench or chassis Dyno? I would presume it is a chassis dyno reflecting power to the rear wheels.

At 5700 RPM's, if your LT1 has a/c, you are into hazardous RPM's for the a/c system.

2003 Dyno sheet is attached, but not real clear.

[Duke W.]

Re: 72 LT-1 Dyno Run

Unless one runs the test with the AC engaged and the compressor on, high revs wont hurt the compressor.

Your chart in unreadable. Winprep7 allows you to extract a dot-bmp file. That's what I used to show John McRae's Special 300 HP configuration performance in the Fall 2009 Corvette Restorer "A Tale of Two Camshafts" article.

Extract the file and try to post it.

Duke

[Jerome P.]

Re: 72 LT-1 Dyno Run

Duke,

I tried to resize the image via editing.

Your comment on the lt1 a/c --- I agree.

[Duke W.]

Re: 72 LT-1 Dyno Run

I still can't see the numbers, but thanks for trying. Undoubtedly this is the test of your LS1. Note the flat torque and power curves and high specific output.

This is what I tried to achieve with the Special 300 HP configuration. The torque/power curves are similarly flat, but one can't get the specific output from a vintage small block (280/220) that GM gets out of their modern V8s and still have a torque curve as flat as the Devil's Tower.

Forty years of development got results!

For anyone contemplating a chassis dyno test, here are some useful guidelines.

1. Find a shop with a Dynojet chassis dyno and a wide band O2 sensor so you can get A/F data. You can search via zip code at dynojet.com

2. Find out what kind of I/O device the computer has and bring suitable media to copy the test files. Alternatively, the test files can be emailed. The actual data files are only a few KB for each run.

3. Dowload and install the free Winpep7 software from dynojet.com, and when you load the test files you can manipulate the views, scales, correction factors, and data shown.

4. Most shops will charge a minimum of one hour, and if you have a well thought out test plan, you can get a lot of data for different configurations, such at timing, air cleaner, etc.

Duke