[Durango_Boy]

Originally Posted by enkeivette

200cc Vortec heads and a 230/238 cam will need at least a 100shot of juice to reach 536 flywheel hp, sorry. BTW, desktop dyno said that my motor NA should have been in the 600s, it was actually in the low 400s after tuning... NA. Desktop dyno is a tricky bitch to get accurate numbers from, I even input the head flow data across the lift points.

Yeah I don't put a lot of faith in desktop dyno programs. Realistically I want 400 HP at the wheels, and even more TQ.

[BRUTAL64]

Originally Posted by enkeivette

200cc Vortec heads and a 230/238 cam will need at least a 100shot of juice to reach 536 flywheel hp, sorry. BTW, desktop dyno said that my motor NA should have been in the 600s, it was actually in the low 400s after tuning... NA. Desktop dyno is a tricky bitch to get accurate numbers from, I even input the head flow data across the lift points.

I don't have Vortec heads. I have Alum China heads that I ported with the 30 30 cam. NHRA put the 327 fuelie at 425 hp in the 60's. Hell, the 302 Trans AM motors of the late 60s were at 440 hp or there abouts. Yea, 536 hp is a "little" high but and a big "but" here any good 400 is capable of 450 hp to 475 hp with the right cam and heads.
Yes, computer dynos are a "little" off, but some of the engine builders I have talked to- that have ENGINE dynos -find them to be VERY helpfull checking changes that they are thinking of doing.

Just for fun I took known engine combs -hp figures etc.- and ran it on the computer, using CORRECT flow numbers and specs. I would get figures within 5 to 10 hp. Who knows what is really right. Just go as fast as you can and hope for the best.

HP figures have ALWAYS been a pain. I've seen guys almost come to blows discussing power figures.

Beer is always the best way to figure out HP.

[Vettezuki]

Originally Posted by BRUTAL64

I don't have Vortec heads. I have Alum China heads that I ported with the 30 30 cam. NHRA put the 327 fuelie at 425 hp in the 60's. Hell, the 302 Trans AM motors of the late 60s were at 440 hp or there abouts. Yea, 536 hp is a "little" high but and a big "but" here any good 400 is capable of 450 hp to 475 hp with the right cam and heads.
Yes, computer dynos are a "little" off, but some of the engine builders I have talked to- that have ENGINE dynos -find them to be VERY helpfull checking changes that they are thinking of doing.

Just for fun I took known engine combs -hp figures etc.- and ran it on the computer, using CORRECT flow numbers and specs. I would get figures within 5 to 10 hp. Who knows what is really right. Just go as fast as you can and hope for the best.

HP figures have ALWAYS been a pain. I've seen guys almost come to blows discussing power figures.

Beer is always the best way to figure out HP.

There are only two classes of HP discussions:
1 - Estimation based on combination theory, hopefully supported by mathematical and historical data (of highly variable accuracy). Always take with a grain of salt.

2 - Measuring on a dyno of some kind. But even this has variance depending on type and chassis losses. For example, my motor with a different tune (more aggressive) and different pair of headers made 432 WHP in a C5. With my more conservative tune and stock manifolds, but better intake and TB, hasn't cracked 391. That's 40 WHP! . . . Measured.

[big_G]

Horsepower is a function of rpm. If the rods limit the useful rev's to 4,500 to 5,000, then the horsepower will be way down. I bet a hamburger on < 325 rwhp on this combo.

[Vettezuki]

Originally Posted by BRUTAL64

. . . Beer is always the best way to figure out HP.

The "big_G" corollary:

HP is a function of how much beer you've been drinking.

[big_G]

Originally Posted by Vettezuki

The "big_G" corollary:

HP is a function of how much beer you've been drinking.

[BRUTAL64]

Originally Posted by Vettezuki

There are only two classes of HP discussions:
1 - Estimation based on combination theory, hopefully supported by mathematical and historical data (of highly variable accuracy). Always take with a grain of salt.

2 - Measuring on a dyno of some kind. But even this has variance depending on type and chassis losses. For example, my motor with a different tune (more aggressive) and different pair of headers made 432 WHP in a C5. With my more conservative tune and stock manifolds, but better intake and TB, hasn't cracked 391. That's 40 WHP! . . . Measured.

Damn, you take all the fun out of this.

[BRUTAL64]

Originally Posted by big_G

Horsepower is a function of rpm. If the rods limit the useful rev's to 4,500 to 5,000, then the horsepower will be way down. I bet a hamburger on < 325 rwhp on this combo.

So true. But rwhp is tricky. A function of friction.

[enkeivette]

Originally Posted by BRUTAL64

I don't have Vortec heads. I have Alum China heads that I ported with the 30 30 cam. NHRA put the 327 fuelie at 425 hp in the 60's. Hell, the 302 Trans AM motors of the late 60s were at 440 hp or there abouts. Yea, 536 hp is a "little" high but and a big "but" here any good 400 is capable of 450 hp to 475 hp with the right cam and heads.
Yes, computer dynos are a "little" off, but some of the engine builders I have talked to- that have ENGINE dynos -find them to be VERY helpfull checking changes that they are thinking of doing.

Just for fun I took known engine combs -hp figures etc.- and ran it on the computer, using CORRECT flow numbers and specs. I would get figures within 5 to 10 hp. Who knows what is really right. Just go as fast as you can and hope for the best.

HP figures have ALWAYS been a pain. I've seen guys almost come to blows discussing power figures.

Beer is always the best way to figure out HP.

I was talking about DBs motor, don't really know anything about the H&C in your motor.

And Glenn, that's what I use the program for, checking changes. Lift, boost, header size, etc.

[enkeivette]

Originally Posted by big_G

Horsepower is a function of rpm. If the rods limit the useful rev's to 4,500 to 5,000, then the horsepower will be way down. I bet a hamburger on < 325 rwhp on this combo.

What's the stock rod length on a 400sb? Is it a problem from the factory?

DurangoBoy, don't get pissed with the our low hp estimates. I know I prob would have in your situation, just realize that if you want 400+ wheel hp, and that's your goal (not a fun torquey DD) than you might want to consider putting your project on hold till cash permits some more aggressive parts. Because come dyno day, I hate to say it, but you'll likely be disappointed. Either step it up or install some juice along with your new powerplant. But for a DD, I think your setup is pushing the comfort zone as it is.

When HotRod tests these cookbook engines, they test them at the crank, with no accessories, with gigantic open headers. And after hours and days and weeks of tuning, they make some pretty impressive numbers. Numbers that you will never see.