Hello from Germany

[olddog]

As said by cycleguy55, if the heads are limiting the power of an engine, stroking the engine gives no gain in power and causes the torque to happen at the lower rpm by the ratio of the displacement change, as I stated earlier.

If the displacement you have and the cam are pulling in all the air of the displacement or more (100 - 100+ efficiency), then stroking the engine will give a huge hp and torque gain.

Your heads are likely somewhere between the two. If I am correct the dyno sheet of your engine has 440 ft-lb peak torque at wheels, which should be in the range of 525 at the crank. That is likely over 100 efficiency with torque being 1.5 times the displacement. So I think the porting on your heads is very good, and likely would do better with a stroker.

AFR are top notch heads, but yours could be as good or better depending on the port work.

[Gaz64]

I was puzzled as to why the two curves don't cross at 5252 rpm, then I realised the the scales are HP and Newton metres.

What dyno operator uses HP (imperial), and Nm (metric).

So you have 441 Nm, not 441 Ft/lbs. 441Nm = 325 Ft/lbs.

So at 5252 rpm, you have about 325 HP, before you then go onto 354 Hp at 6600 rpm.

[Max Power]

Originally Posted by olddog

As said by cycleguy55, if the heads are limiting the power of an engine, stroking the engine gives no gain in power and causes the torque to happen at the lower rpm by the ratio of the displacement change, as I stated earlier.

If the displacement you have and the cam are pulling in all the air of the displacement or more (100 - 100+ efficiency), then stroking the engine will give a huge hp and torque gain.

Your heads are likely somewhere between the two. If I am correct the dyno sheet of your engine has 440 ft-lb peak torque at wheels, which should be in the range of 525 at the crank. That is likely over 100 efficiency with torque being 1.5 times the displacement. So I think the porting on your heads is very good, and likely would do better with a stroker.

AFR are top notch heads, but yours could be as good or better depending on the port work.

re: the heads, I am stuck with them. The TUV made a notation on my registration what engine components I have and I cannot change these notated items out without going through a lengthy and expensive approval process. Sometimes, they even note the size of the the tires on your registration and you cannot change tire or wheel sizes. The police really come down hard on unapproved changes. They like to park outside US Army bases and pull soldiers over and hassle them for unapproved mods.

I don’t think these heads are too much of a limiting factor. they should be capable of nice power with the right cam. they flow more than AFR 165s but slightly less than AFR 185s. Engine masters put afr 165s on a 408W and a small cam it made 471 hp and 515 ft/lbs, all at 5500 rpm or less. I would like to replicate this kind of performance.

THis crate makes 475 hp with the same heads and intake only mine have been ported to flow 20 cfm more at .600 of lift so I should be able to replicate this motor and do even better. I just don’t know what cam they use. It is funny. For their 383 chevy engines, they list the head p/n and the comp cams grind # but they wont tell me what grind they are using on the cam

https://enginefactory.com/ford-perfo...s/408w-475-hp/