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Discussion Starter #1
I just had my car on a dyno (rear wheel) and it showed lower numbers than I expected. Without going into the detail of the engine I bought it came with a dyno report that I assume was a computer model of the build.

The computer model, I don't have it in front of me right now, showed to to make over 500HP. The rear wheel dyno showed 317HP and 355 torque.

Should I expect that much loss through the drive train?

The dyno was performed by the Carol Shelby Automotive school at a local community college on a Dynojet Research machine. 2 runs were recorded and they were within 5 points of each other.
 

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I just had my car on a dyno (rear wheel) and it showed lower numbers than I expected. Without going into the detail of the engine I bought it came with a dyno report that I assume was a computer model of the build.

The computer model, I don't have it in front of me right now, showed to to make over 500HP. The rear wheel dyno showed 317HP and 355 torque.

Should I expect that much loss through the drive train?

The dyno was performed by the Carol Shelby Automotive school at a local community college on a Dynojet Research machine. 2 runs were recorded and they were within 5 points of each other.
That would equal about 400 at the crank. I would not worry about the low numbers. rear wheel dynos are great for tuning. take it to the track with some sticky tires and then you will see how much power it makes. How about some specifics on the engine. Did you make any changes with the jets and timing?
 

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Discussion Starter #3
I will get back with you in a couple of days with the engine build specs, it is in another city right now.
 

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Discussion Starter #4
Here is the 460 engine build:

Stock block 30 over
Ported iron heads with stainless valves 2.19 int and 1.76 exh, pocket porting
Comp cams roller rockers with stud conversion, push rods
Torker II intake with heat cross over welded up
Stock Crank
Hypereutectic pistons
Stock Rods with ARP hardware
Lunati Bracket Master II #00097 with .554 lift on int and exh
Hydraulic flat tappet lifters
Engine was balanced
FPA shorty headers
Holly 80508S carb
Stock C6
3:50 mini spool Ford 9"
 

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Discussion Starter #5
Forget all of your question:

Did not change or mess with the Holley in any way, it is out of the box.

I did set the timing to 13 degrees, I forgot if it was advanaced or retarded (like Me).
 

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You have losses. Some in the driveline, and some in tuning. You already know this, but running on a chassis dyno is nearly useless without testing changes for relative effect. The Shelby guys should know this, and should know this is not how a chassis dyno is used. All you got was a sheet of paper that says you need to work on it. Can you get a block of dyno time to make the exercise worthwhile?

David
 

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Discussion Starter #7
PSIG, to be fair to the Shelby guys they were offering 2 pulls for $35 which all went to charity for the car show they were hosting. And - I didn't understand how a chassis dyno was used, like other novices I just heard people quote their HP and TQ from having their car tested on a dyno.

It makes all the sense in the world to use the numbers generated as a bench mark for changes made to see if things got better or worse. I got it!

I will ask about a block of hours, but since they are a full time teaching school I am not hopeful they will do it.
 

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I hear ya. But, they could use your car to teach basic adjustments and reading results on a classic old-school setup to the students. Basic real-world stuff. Maybe some emissions-tuning instruction as well.

If their students are going into the performance market for jobs, learning how to do this to your volunteered carb-and-distributor car would be a basic prerequisite to gainful employment. I assume they are not just turning-out graduates that only understand tuning with a laptop. Give it a shot - for the kids, ya know. ;)

David
 

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80508S is a vacuum secondary Holley 750. Comes with 70 primary jets and equivalent secondary plate to a 75 jet. I am going to guess that you were a NUDGE lean with that.

Lunati cam, 292 advertised, 1800 to 6000. With your carb like that I don't think you could pull to 6000. It probably runs out at less than 5000. The rest looks ok to me.

Initial timing might help to be bumped to 16 or so but it depends on your compression ratio.
 

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Discussion Starter #11
The MSD started cutting out cylinders at around 5500 RPM on the dyno. I had the timing at 16 but it was pinging so I turned it back to 13, I think. I need to check it again. I don't know for sure what comp ratio it has, but the computer model I got with the engine used 10/1 ratio.
 

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The MSD started cutting out cylinders at around 5500 RPM on the dyno...
How do you know it was the MSD cutting-out cylinders?

David

PS: Can you post scans of the dyno pulls?
 

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Discussion Starter #14
I have 2" exhaust pipe from the FPA headers back with Magnaflow mufflers.

When I heard the cylinders banging at the end of the pull I said something to the instructor about valves floating. He said no it was the MSD dropping cylinders to limit the RPM and I do remember putting in the RPM limiter plug when I installed the box, I think it was 5500 or 6000.

I will post the dyno chart later this week. It also has the air/fuel mixture shown.

Thanks for all the feedback.
 

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I have 2" exhaust pipe from the FPA headers back with Magnaflow mufflers.
The tiny 2" exhaust is costing you BIG power behind a warmed up 460! You need no less that 2.5" with see through mufflers, and preferably 3".

Cross sectional area of different sized pipe:

2.0" = 3.14 sq in
2.5" = 4.91 sq in
3.0" = 7.07 sq in

With 2" pipe, you are WAY under sized!
 

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Yeah, the rev limiter is low, as that cam should go over 6000. I agree about the exhaust, and do at least replace the section from the headers to the mufflers with 3" and use good 3" internal mufflers. Many mufflers neck-down inside to a smaller size than the inlet, so check that. If you want to prove if it's an issue before throwing time and money at it, do pulls with open headers as a baseline. The sheets should also show it flatten or nose-over from choking.

Keep in-mind, the dyno numbers that come with most engines are for dyno HP, meaning no air filter, a ram stack, open headers and cooler water, etc. So, you can expect lower HP just from your install. Again, chassis dyno HP should not be used as a benchmark, but a relative gauge. Just lowering or raising your tire pressure can lose or gain you 20 hp. Not saying your numbers are good, and you need some stuff changed, but keep it relative until you can get to the track for some real performance measurements.

David
 

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Discussion Starter #17
I haven't found a shop with a mandrel bender in rural East Texas, and I have read how difficult it is to get anything over 2 1/2 over the rear axle on a 67 Galaxie. I think the Magnaflows are 3" mufflers. I can have the header to muffler section changed to 3". How much will that really help.
 

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I haven't found a shop with a mandrel bender in rural East Texas, and I have read how difficult it is to get anything over 2 1/2 over the rear axle on a 67 Galaxie. I think the Magnaflows are 3" mufflers. I can have the header to muffler section changed to 3". How much will that really help.
99.9% of muffler shops do not use mandrel benders. Most people purchase mandrel bent systems made to go on their model car, or fabricate mandrel bent exhaust systems from welded together pipe for cars that kits aren't available.

If a kit isn't available for you car, Summit sells universal mandrel bent kits that can be made to work.

If you're on a budget, you can run muffler shop bends back to the mufflers, as those aren't tight bends, and then fabricate some mandrel bent tail pipes.

The Summit kits are probably a good place to start.

Good Luck!
 

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If you're not in a rush, go to Columbia River Mandrel Bending and get on their B-stock list of clearance and blemished stuff. Cheap. Even the "oops" bends are fine for fabbing and fully usable. Use an old tailpipe to plan your angles, and order what you can off the cheap list.
:tup:
David
 

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Likewise to what David offered, I get my mandrel bent pipe from these guys:

Mandrel Bending Solutions Home Page

Custom single bends are the same price as standard stocked items-and them bend them in-house. Bends are usually sent out the next day in a sturdy box.
 
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