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Old 09-22-2023, 01:45 PM   #1
-Greg72
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502BBC in a '72K5.... EFI & NITROUS (!! DYNO VIDEOS INSIDE !!)

All,

It's been more than 5 years since this engine project began... collecting parts, figuring out a complete build plan but it's finally finished and ready to install back into the 1972 K5 Blazer (IG: @MIGHTASWELLK5)

With all the hysteria around LS-swaps over the last several years, it seems that anything related to old-school, big cubic inch power is a lot harder to find.

So... for those of you who ARE interested, here are a couple of dyno videos from 2-weeks ago of a 502BBC with a Holley Dominator TBI setup, nice Brodix aluminum heads and mild compression (9:1) so it can still run on pump gas. The objective I gave the engine builder was to give this engine a very mild demeanor, and an idle as close to "stock" as possible.... also asked him to do everything possible to maximize low-end TQ, even at the expense of a large peak HP number.

Heath over at VolcanoManifolds.com did all the work and deserves all the credit here... but I still wanted to share the results because these videos sound awesome, and the final power numbers (especially TQ) are pretty mind-blowing for a simple pump-gas motor.

You just can't get a normaly aspirated engine to lay down a big, flat TQ curve (especially down at low RPMs) without lots of cubic inches... and this classic BBC does not disappoint

Hope you all enjoy it!!


FIRST PULL: Normally Aspirated

https://www.youtube.com/shorts/Gnnd0ssUC3w





NITROUS PULL: ADD 100-SHOT AT 3800 RPM


https://youtube.com/shorts/swlkd7dSHdc




-G
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1972 K5 - 502BBC/4L80E/Magnum205/Mog-9s/5.26s/38" BFG KM2s


Find me on INSTAGRAM @MIGHTASWELLK5

'72 K5 - Greg's "Might As Well™" Build

Last edited by -Greg72; 09-22-2023 at 06:38 PM.
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Old 09-22-2023, 03:33 PM   #2
Ziegelsteinfaust
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Re: 502BBC in a '72K5.... EFI & NITROUS (Dyno Video)

That is a nice flat torque curve. I wonder how well it would pull down at 2000 rpm.

My Uncle Ron had a 502 truck motor in a 55 GMC 4x4 wrecker he used. It would get 14 mpg on the Idaho state highways with a TH400, and pretty aggressive 34's.
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Old 09-22-2023, 03:41 PM   #3
RustyPile
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Re: 502BBC in a '72K5.... EFI & NITROUS (Dyno Video)

I totally agree.. Nothing beats cubic inches.. The torque curve in my 454 is just that flat, although the numbers are smaller.. Doesn't make big HP numbers but it will drag around by the nose anything that gets tied to it...
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Old 09-22-2023, 03:42 PM   #4
-Greg72
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Re: 502BBC in a '72K5.... EFI & NITROUS (Dyno Video)

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Originally Posted by Ziegelsteinfaust View Post
That is a nice flat torque curve. I wonder how well it would pull down at 2000 rpm.
.

Funny you should say that.

When we were coordinating this dyno session, I asked for the lowest possible dyno pulls RPMs to see what sort of "off idle" TQ this engine would make.

When it came time to actually do the pulls, Heath (engine builder) called me and said that the dyno shop was having a heck of a time trying to hold the engine back at anything below 3400 RPM. I guess there are some modern dynos that can do it more easily.

Ultimately, if you extrapolate those numbers down toward 2000RPM it's such a gentle downward slope that I would be surprised if it ever went below 550TQ.

It will be installed into a big, heavy truck with tall tires... but it's got deep gearing (5.26 axles)... I have a feeling that with this much TQ and such a broad, flat curve it is going to feel pretty lively and quick.


-G
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1972 K5 - 502BBC/4L80E/Magnum205/Mog-9s/5.26s/38" BFG KM2s


Find me on INSTAGRAM @MIGHTASWELLK5

'72 K5 - Greg's "Might As Well™" Build
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Old 09-22-2023, 03:46 PM   #5
-Greg72
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Re: 502BBC in a '72K5.... EFI & NITROUS (Dyno Video)

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Originally Posted by RustyPile View Post
I totally agree.. Nothing beats cubic inches.. The torque curve in my 454 is just that flat, although the numbers are smaller.. Doesn't make big HP numbers but it will drag around by the nose anything that gets tied to it...

Yep! The engine builder kind of laughed and said my biggest problems from now on aren't going to be power... it's going to be traction. The nitrous run was fun for bragging rights, but ultimately unless I'm in the sand dunes with paddle tires bolted on... I'm not really sure there is any point to pushing that button at all.


-G
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1972 K5 - 502BBC/4L80E/Magnum205/Mog-9s/5.26s/38" BFG KM2s


Find me on INSTAGRAM @MIGHTASWELLK5

'72 K5 - Greg's "Might As Well™" Build
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Old 09-22-2023, 08:29 PM   #6
D.B
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Re: 502BBC in a '72K5.... EFI & NITROUS (Dyno Video)

Those are some very good numbers and it does not take much to make good street friendly power out of a big block. I built a 511 for my 72 C20 that runs on pump gas with Edelbrock Perf RPM heads, Perf RPM Airgap intake, Demon 850 carb and a Crane Roller cam. And it makes all of its power down low. Very impressive feeling when driving it. I wish my dyno guy was able to give me a graph but I settled for this print out.

Not bad, it makes 671 ft lbs at 4200 rpm and 588 hp at 5200 rpm. The dyno pull started at 3200 rpm and it was already making 648 ft lbs. Like I said, it is fun to drive.


Name:  C20 511 CID.jpg
Views: 71
Size:  88.0 KB


It has Air Conditioning and a Turbo 400 auto with 4.10 gears. And a Gear Vendors so I can run the highway at 70 mph.
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Old 09-25-2023, 02:35 PM   #7
-Greg72
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Re: 502BBC in a '72K5.... EFI & NITROUS (Dyno Video)

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Originally Posted by D.B View Post
Those are some very good numbers and it does not take much to make good street friendly power out of a big block. I built a 511 for my 72 C20 that runs on pump gas with Edelbrock Perf RPM heads, Perf RPM Airgap intake, Demon 850 carb and a Crane Roller cam. And it makes all of its power down low. Very impressive feeling when driving it. I wish my dyno guy was able to give me a graph but I settled for this print out.

Not bad, it makes 671 ft lbs at 4200 rpm and 588 hp at 5200 rpm. The dyno pull started at 3200 rpm and it was already making 648 ft lbs. Like I said, it is fun to drive.

It has Air Conditioning and a Turbo 400 auto with 4.10 gears. And a Gear Vendors so I can run the highway at 70 mph.

Nice numbers!!!

I put your HP/TQ Data into a graph for you... seems like a shame not to have this






-G
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1972 K5 - 502BBC/4L80E/Magnum205/Mog-9s/5.26s/38" BFG KM2s


Find me on INSTAGRAM @MIGHTASWELLK5

'72 K5 - Greg's "Might As Well™" Build
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Old 09-25-2023, 08:15 PM   #8
D.B
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Re: 502BBC in a '72K5.... EFI & NITROUS (Dyno Video)

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Originally Posted by -Greg72 View Post
Nice numbers!!!

I put your HP/TQ Data into a graph for you... seems like a shame not to have this






-G
Thanks Greg, this cool.
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