My 431 stroker Build and Dyno

[Lenz]

Checkbook indeed . 

I've enjoyed this thread, especially the expected dyno results versus actual results achieved and the factors that can affect them. 

As with most things, in the end its the human inputs that result in the best representation of the truth or a slightly modified and more marketable version thereof.

[abyars]

Looks like you'll be having a ball with that engine.  Nice build

[Fine69mach1]

I have the cam card now from the builder and the specs are nothing like any of the combinations I've seen before from comp crane or luniti.
The guy who provides these custom camshafts for my engine builder likes to keep the info on his camshafts quit.  Doesn't like to share the specs.
After seeing these specs and how they are quite different than your traditional cam specs I believe he has found a unique combination with my build that has resulted in results that aren't common for the traditional stroker build.
What I will say is it is a large split duration( large split between int/exh) and has more intake lift than exh.
Also the static compression came out at 10.3 higher than the anticipated 9.8
I also think that it is possible that the Dyno could be a " happy Dyno" and my results might be a few percent stronger.
He does have a weather station in the ducting and it was set at 60F and at sea level. Standard correction.
The Dyno is a land and sea Dyno-max "pro"
I tried posting Dyno results but it says my image is too large from my smartphone.
Hopefully next season I can get some time slips that hopefully back up my Dyno sheets.

[ScotiaFE]

Good one. A secret cam.
That's always good for an extra 75 or so on the BS meter.

[bn69stang]

Yes Howie , this is national security we re talking about , and are the b s meters calibrated at ...? lol

[jayb]

I have the cam card now from the builder and the specs are nothing like any of the combinations I've seen before from comp crane or luniti.
The guy who provides these custom camshafts for my engine builder likes to keep the info on his camshafts quit.  Doesn't like to share the specs.
After seeing these specs and how they are quite different than your traditional cam specs I believe he has found a unique combination with my build that has resulted in results that aren't common for the traditional stroker build.
What I will say is it is a large split duration( large split between int/exh) and has more intake lift than exh.
Also the static compression came out at 10.3 higher than the anticipated 9.8
I also think that it is possible that the Dyno could be a " happy Dyno" and my results might be a few percent stronger.
He does have a weather station in the ducting and it was set at 60F and at sea level. Standard correction.
The Dyno is a land and sea Dyno-max "pro"
I tried posting Dyno results but it says my image is too large from my smartphone.
Hopefully next season I can get some time slips that hopefully back up my Dyno sheets.

If you want to email me the dyno sheets I can post them for you.  jayb@fepower.net

Good luck at the track, I hope the ETs back up your horsepower numbers!

[plovett]

The numbers aren't right.  Simple as that.  I tried to be polite in my first post and just ask for more info, but that isn't forthcoming apparently. 

It may still be an awesome engine.  It doesn't make the power numbers you stated though.  I'll stand by that.

I have a similar size FE at 432.7 cubic inches.  With a bigger bore, well ported Ebok heads, 10.5:1 compression, 2" headers, an aggressive 240/246, .580/.593" net lift, solid flat tappet cam, it made 517hp at 6200 rpm and 522 ft/lb .  The rpm is important.   How do you make more hp at a lower rpm with less compression with the same displacement?  A magic cam that you won't share the spec's of?  Nope.   

Now I have a bigger solid cam with 252/260 degrees and some other changes and I think I am making around the hp you mention, but nowhere near the torque.  And my peak hp is closer to 6600-6700. 

Like I said, I bet it's a great motor, but doesn't make the numbers you posted.

JMO,

paulie

edit:  moved 6200 rpm in front of 517 hp.

[jayb]

Fine69Mach1 was kind enough to email me the dyno data, so I have posted it below:







I'm going to take the liberty of pointing out some discrepancies in this data, but regardless of what the horsepower and torque numbers say this is a pretty strong FE.

Using cfm numbers you can get a pretty good idea of what the horsepower output of an engine is; you can go to my post here to get more information on this:

http://fepower.net/simplemachinesforum/index.php?topic=928.15

We'll just look at the last dyno sheet, which has the biggest numbers.  At the torque peak of 4400 RPM, the horsepower is 503.8, and the engine airflow is 564 cfm.  This data is corrected to sea level, and at sea level air weighs 0.075 pounds per cubic foot.  Also, one pound of air at sea level can generate almost exactly 10 horsepower, assuming gasoline for fuel and a perfect air/fuel mixture.  So, 564 X 0.075 X 10 is 423 horsepower.  The dyno data of 503.8 is pretty optimistic, I think.  410-420 horsepower is probably reasonable given this airflow, and the associated torque at this horsepower level and 4400 RPM is (420 X 5252)/4400, or 501 lb-ft. 

Up at the horsepower peak of 547 shown on the dyno data, cfm is 661.2.  Using the same calculation, horsepower is 495.9 based on cfm.  This is closer to the dyno data, but still off by a ways.  The engine is going to be less efficient once it is past the torque peak, so I think a horsepower level of around 475 would be a reasonable guess on this one.

One other calculation we can do is with the first dyno sheet, that shows the volumetric efficiency.  VE is 93.24% at 4400 RPM (torque peak), and the engine is 431 cubic inches.  The airflow should be half the cubic inches (one revolution of the engine will fill half the cylinders in a four stroke engine) multiplied by the engine speed and the VE, all divided by 1728 (1728 cubic inches per cubic foot).  So, (215.5 X 4400 X 0.9324)/1728 is 511.6 cfm.  The dyno sheet says 554.3.  So, there is a discrepancy here also. 

I don't know how Land and Sea dynos work, but my dyno calculates the VE by taking the cubic inches of the engine at any given RPM to calculate cfm and comparing it to the measured cfm.  At the beginning of the dyno session you have to input the cubic inches of the engine.  What may have happened here is that the cubic inches of the engine was not input correctly.  Using the dyno sheet values of 93.24% VE and 554.3 cfm, my dyno would need an input cubic inch value of 467 cubic inches. 

Bottom line is that its difficult to tell exactly what is going on here; the only thing we can say for sure is that these numbers don't add up...

[blykins]

I don't know of any "race shops" that use Land & Sea dynos.  They are generally not reputable as a good "dyno standard". 

Keep in mind that we are not trying to rag on you, but the results are just not typical and are pretty inflated...even with the secret cam specs. 

[ScotiaFE]

Yes that FE is sucking in a pretty good volume of air for a mild 431.
All the more reason you should be proud of your cam selection.

In a light weight Stang it is a tire shredder.  Have Fun.

[bn69stang]

Yep with 3.91 s you will have fun , its still a healthy f e ..Bud

[Fine69mach1]

I appreciate the educational info Jay. As I have previously mentioned. This is my first FE build and was and still is a learning process. Either way this motor has exceeded my expectations and am looking forward until next spring to get it on the road as I live in Canada and we will be getting snow any day now.
I am building a C6 with a 3000 stall converter. Do you guys feel a 3000 stall is adequate judging by my results?

Thanks

[thatdarncat]

Glad you forwarded your dyno info to Jay, this has been a good discussion. To decide on a torque converter we'll need some more info to give a good answer - first being how is it going to be used? Is this going to be mostly a race car or a crusier? This is also a case were accurate dyno results and actual cam specs would help. Those are the questions a good converter company will ask. If the stall speed is too low and the cam is "racy" the combination will not be happy, the car will be hard to keep idling while stopped, etc. The stall speed is not an absolute either, the same converter would vary if switched from one vehicle to another with different combos. The stall speeds you see advertised are just approximations, good converter companies will ask a lot of questions. I'll also add you tend to get what you pay for with converters, more expensive ones tend to have stronger parts inside, torrington bearings, etc., another reason we will need to know what you intend to do with the car. If it's drag race, go with a good race converter.

[jayb]

Here's a picture of the engine on the dyno:

[Joe-JDC]

How does anyone think they can control the parameters with that air box tubing fitted like that?  That within itself is a give away to the quality of the data.  JMO, but no dice.  Joe-JDC