Horsepower Calculator

[moose]

Does anyone know how to roughly estimate an engines potential horsepower at the flywheel?

All I have are basic numbers and after trying a few online calculators I was curious to see if they are remotely in the ballpark.

I tried this calculator: http://www.wallaceracing.com/hp-bore-stroke.php
and the results seemed overwhelmingly generous, 390HP. Bore size-4.16 Stroke-3.75 8 cyl.

This one estimates 335HP: http://www.bgsoflex.com/roughhp.html
407.75CID or 6.7liters, I'm shooting for 9.5 compression after decking but entered 9 to be safe, at 5000RPMs. Since it says rpms where peak hp will occur, I assume this calculation is for mainly strip and racing applications. I'm trying to estimate HP for an engine I'm building to swap into my daily driver, so I re-entered the numbers with 3000RPMs, for low cruising speed. I end up with the guesstimate of 201HP.

The reason for asking is because I'm hopeing to use this fuel system http://www.jegs.com/i/Aeromotive/027/17245/10002/-1 it was an impulse buy for a project car I'm giving up on.
I know if it doesn't produce enough HP it'll be bad news for the motor. I think it will work, if anyone dissagrees please let me know. The engine I am now going to use is a Pontiac 400 bored .040 with Pontiac 5C heads, 101cc and dome pistons. When it comes to shaveing off metal should I have the heads decked or the block?

 

[dogsht]

It takes a lot of good info to make a decent educated guess unless you have results of a VERY similar engine. Heads airflow valve job info cam compression etc. The fuel system should be more than adequate based on what you have said. Decking the block is usually and ideally the best but their can be exceptions based on trying to use existing parts such as pistons.

Food for thought compression is efficiency ie both better power and mileage right up to the point of detonation with a particular fuel & conditions weather etc. I don't have the address handy but KB (keith black) pistons is one of a few sites on the net that has a simple calculator for calculation both static and dynamic compression in so teaching you what basic engine measurements are needed for GOOD engine building. In doing so you will see between block deck, gasket thickness, head milling and different pistons choices you can get such things as ideal quench (35 to 40 thou) to be able to run an actual measured 10+1 compression on pump premium with cast heads without detonation. Learning about good engine building machining measuring and assembly is fun and challenging. Have fun.

 

[kingcolbert83]

Been wondering the same thing. Seems every calculator is either too simple or overly complicated even with the required info.
Here are the stock specs on my motor in general if it matters and just for future reference and comparison

Buick 430(67-69 Buick Riviera's)
360hp@5000
475ft.lb@3200
4.1875(bore)x3.90(stroke)
10.25 to 1 compression

Mods to motor are 455 heads, edelbrock intake and carburetor. Motor is rebuilt with all new parts, standard bore and heads have 3 angle valve job with stock size valves.

 

[megaladon6]

no matter what it's a guess. unless you take the measurements of your engine, do you really know your compression? the only true "calculators" are the track and the dyno.

 

[moose]

no matter what it's a guess. unless you take the measurements of your engine, do you really know your compression? the only true "calculators" are the track and the dyno.

I know it's all speculation until you get a dyno to spit out physical proof. I'm using this calculator to estimate what my compression rate will be http://www.wallaceracing.com/cr_test2.php
My current number estimate 8.13 compression, after decking I'll be in the 9-9.5 ratio.

I know the Aeromotive kit is more than sufficiant, i'm just trying to figure if it'll be too much.

 

[dogsht]

Moose, http://www.kb-silvolite.com/calc.php

Kingcolbert, I told you second to the big Caddy the Big Buick is my second favorite performance street engine.
http://www.v8buick.com
http://www.gesslerheadporting.com
http://www.trishieldperformance.com
www.taperformance.com

 

[moose]

Hey thanks for that calc link dogshh...ca..can we say sh*t on this forum? :lol: Anyway, much appreciated!

 

[kingcolbert83]

Moose, http://www.kb-silvolite.com/calc.php

Kingcolbert, I told you second to the big Caddy the Big Buick is my second favorite performance street engine.
http://www.v8buick.com
http://www.gesslerheadporting.com
http://www.trishieldperformance.com
http://www.taperformance.com

I still have a 455 for my next project. I actually hope I can get rid of it so I can have an excuse to get the caddy 500.