Help me figure out my HP....
 

I ran this thread under a different title without any response, I thought I might give it one more try with a different title..............

My engine is done. I need some help with a rough assesment on what kind of HP I am looking at. I plan on doing a dyno run at some point in the future but right now its not feasable.
If one of you guys is versed in the use of the desktop dyno I would really appreciate you giving me a "run".
Even if you don't have a dyno and are running a similar setup your input would be appreciated.
The engine is a 68' 427 side oiler bored 11 thousandths over standard bore, 428 Scat crankshaft, Eagle connecting rods, flat top Diamond pistons with valve relief, Ferrera stainless valves (I think 2.09 is the inlet sizing, notes not avalilable) Comp Cams Magnum 282S solid lifter cam, 571 lift with 282 duration, Dove roller rocker valve train,
Edelbrock RPM performer FE heads with 76CC chambers, A Blue thunder dual quad intake manifold with a set of Holley 750 four barrels. MSD 6AL ignition system. Along with a the above is a 28lb. steel flywheel. Engine has been balanced and blueprinted.
Our numbers tell us we are running 11:1 compression ratio, with a HP guesstimate of 535+. If anyone checking this thread can give me some insight I would really be thankful.
Opinions have been flowing but I really need a touch of reality in working this out. I realize this would be HP at the flywheel and if any more info from my end is needed please let me know.
Thanks much in advance.

Mark

If you can get a couple of 1/4 mile passes under your belt you can use your trap speed to calculate the HP if you know the weight of your car (& driver).

Google something like "HorsePower Calculator 1/4 mile ET" and a bunch of sites will come back. All sites will say that the results are not 100% accurate (choose the one you like or average them) but I imagine that it will be a lot closer than an assessment made on the basis of a list of components.

Plus you can have fun at the same time

LoBelly

Here is one of those web sites to help figure out your HP. Have fun!
http://www.speedworldmotorplex.com/calc.htm

Mark, if you wait until this afternoon when I get home, I'll be more than happy to run it on Desktop Dyno for you.

Have the heads been touched?

I'd say your estimate is pretty reasonable.

"I'll be more than happy to run it on Desktop Dyno for you."

Blykins, what is "Desktop Dyno"? Is that a computer program? Sounds interesting!

Yes sir. Not one of the best, but I've found it to be accurate. It was 6hp off on my last build....not too shabby. If you have the right info to put in it, it works great.

If I had to guess based on the Cobras with similar mods I dyno here at my shop (chassis dyno), I'd guess about 520 at the motor, and 430 at the wheels.

Blykins, where did you get the program and useing the program what engine info is required? Sounds pretty neat!

427SnakeSC

Desktop Dyno is a program that runs on a PC under Windows. You can purchase it and/or other engine simulation software from this site

http://www.proracingsim.com/purchasejac2.htm

Mark, Desktop Dyno showed 492hp @ 5500 and 551 lb-ft at 4000.....the graph shows an extremely flat torque curve with a peaky hp curve.

I think your cam is holding you back from your 535 estimate.

I used a solid flat tappet custom grind spec that Keith Craft gave me one time... 248/252 with a .608/.610 lift. It popped it up to 519, but lowered the torque to 535.

If you want me try any other simulations, let me know......

Thanks Brent,
I went the "mild" (if you can call it that) route on the cam until I can get a better understanding/feel for this engine and its behavior.
Tourque was my primary objective when putting this motor together with a "concession?" being made to HP until I get a better handle on its "behavior"
I did however use the upgradeded spring package if indeed I decide to use a cam with more lift-longer duration.
The heads have been ported and all the runners have been polished.
Lobelly, Sal and Snake...I thank you all for the input and helping me out on this.
If the numbers are showing close to 500 hp and over 500 ft. lbs of torque, thats pretty close to my original guesstimate and what I was hoping for when I did my formulations.
I think I have a pretty solid bottom end and as I get a feel for the beast I can modify according to what I want.
I've already been looking hard at fuel injection..but...I'm gonna take my time
Brent if you get a chance to rerun the specs and take into acount the ported and polished heads that would be great and thanks again.
Mark

Mark, without precise flow numbers and lifts, I can't really do much else with it. The heads I used were KCR Stage 1 heads....I found several sets of flow numbers and averaged them. Keith does a little bowl work and backcuts the valves on the Stage 1 heads. The Stage 2 heads are CNC ported and flow almost 310 cfm where the Stage 1's flow about 270.

If you had them on a flow bench, send me the results and I'll stick in the program.

Let me know if I can do anything else to help!

Thanks again Brent, your efforts are appreciated!
Next time I do a teardown maybe I can get those heads on a flow bench.
My son and I did the port and polish work on these, another aspect of the father son build project, and we were rather conservative on the amount of material actually removed. I am confident we increased the flow capacity but how much?, I'm not sure.Thanks for your response.
Best Always,
Mark

It's awesome to work on a father/son project. I'm 28 and I probably wouldn't have started another engine build if I couldn't have done it with my dad. That means a lot.

One thing I've learned as I've gotten older is that other people are getting older too....and time goes too quickly.

You're a good dad.....