Offshoreonly.com

Offshoreonly.com (https://www.offshoreonly.com/forums/)
-   General Q & A (https://www.offshoreonly.com/forums/general-q-20/)
-   -   HP estimates on a 598 I'm having built ? (https://www.offshoreonly.com/forums/general-q/380420-hp-estimates-598-im-having-built.html)

cdaniel525 09-01-2023 10:10 AM


Originally Posted by articfriends (Post 4878527)
same heads off your 632, cam specs?
your current combo on my sim tq peaks at 5000/ hp peaks at 5900 to 6000

Ya if you can run it with what my old 632 was b4 I blew her up: 632 (10:1 comp) with AFR CNC 335 heads, hydraulic cam: 262/270 --- .720/.720 lift --- 112 LSA, Edelbrock Super Victor intake, and dominator

https://cimg4.ibsrv.net/gimg/www.off...93eb8f4da1.jpg

articfriends 09-01-2023 12:41 PM

tells me 848 tq at 4700 and 820 hp at 5600 (with your exhaust and 1050 carb)

cdaniel525 09-01-2023 01:15 PM


Originally Posted by articfriends (Post 4878544)
tells me 848 tq at 4700 and 820 hp at 5600 (with your exhaust and 1050 carb)

Damn, if that's accurate I was swinging the RPMs way higher lol

Mind if I ask what your simulation app is? I still mess with desktop dyno 2000 lol

KAAMA 09-05-2023 11:31 PM


Originally Posted by cdaniel525 (Post 4878328)
Curious on what you guys think I may come up with on a 598 I'm having built...
Here's my spec'd build so far:
Dart Big M 10.2 block
598 rotating assy
10:1 comp. ratio
Brodix Xtra-O 351cc Flow #s -
.
Thanks in advance!

I was able to locate some 8-10 year old threads and bring them up out of the archives that might help you and give you some ideas regarding 598" engine combos, etc

articfriends 09-06-2023 04:04 AM


Originally Posted by cdaniel525 (Post 4878550)
Damn, if that's accurate I was swinging the RPMs way higher lol

Mind if I ask what your simulation app is? I still mess with desktop dyno 2000 lol

Performance trends anylizer plus . The tq comes up a little generous when I sim stuff vs what I actually see on my dyno, as long as you dont lie to yourself when inputting manifold efficiency the hp is close, still sims up high most time BUT gives you a idea

cdaniel525 09-06-2023 07:11 AM


Originally Posted by KAAMA (Post 4878920)
I was able to locate some 8-10 year old threads and bring them up out of the archives that might help you and give you some ideas regarding 598" engine combos, etc

Thanks, I went and did that and ran across quite a few with impressive #s in the range I'm looking in so that's promising.



Originally Posted by articfriends (Post 4878923)
Performance trends anylizer plus . The tq comes up a little generous when I sim stuff vs what I actually see on my dyno, as long as you dont lie to yourself when inputting manifold efficiency the hp is close, still sims up high most time BUT gives you a idea

Cool, thanks man.... I'll check it out 👍

ICDEDPPL 09-06-2023 08:48 AM


Originally Posted by articfriends (Post 4878544)
tells me 848 tq at 4700 and 820 hp at 5600 (with your exhaust and 1050 carb)

Is it accurate to say that for each 1 lbs/hr of fuel flow equals about 2hp?
So if Im using 614lbs/hr accurate to say 1200hp?

SB 09-06-2023 08:54 PM


Originally Posted by ICDEDPPL (Post 4878950)
Is it accurate to say that for each 1 lbs/hr of fuel flow equals about 2hp?
So if Im using 614lbs/hr accurate to say 1200hp?

Not really.
a roots blown engine uses a bunch more lbs/hr than a comparable na motor.

ICDEDPPL 09-06-2023 09:43 PM

Boosted: Given number of lbs/hr / 0.60 BSFC = HP (for gas)

1023HP seems more accurate .

articfriends 09-07-2023 05:50 AM


Originally Posted by ICDEDPPL (Post 4878950)
Is it accurate to say that for each 1 lbs/hr of fuel flow equals about 2hp?
So if Im using 614lbs/hr accurate to say 1200hp?

From what Ive seen on my dyno :
typical NA 9.5-1 509 tuned safe rich to 12.2 to 12.5 at wot BSFC of .550 to .580 from 5500 up
roots blown BBC tuned to 11.8 -12.0 at wot .600 to .680 light boost , ie 4, 5 lbs
roots/whippled bbc tuned to 11.4/11.5 at wot ..680 to .750 , talking 3.3s, 2.3s at 7 to 9 lbs of boost.
The richer you drive your target down, the higher your BSFC number, ie, lbs he per hp used.
So in automotive world BSFC is a good measure of efficiency , its still a measure of efficiency in the marine world BUT the majority of guys with boosted BBC's in boats have them tuned max rich to edge of where power decays or even past point where power decays to keep from melting pistons on hot cylinders, ie "safe tune" .
FOR EXAMPLE, using big , rounded off numbers, I can literally dyno same blower engine tuned to say 12.2 , make 1000 hp , use 650 lbs fuel (.650 BSFC)
drive AFR down to 11.5 , so our target is 6% RICHER, lets say it makes same 1000 hp for sake of discussion, now the theoretical fuel used is 690 lbs, our BSFC is now .690. Lets say its fuel injected though and the power drops to 950 hp but were shoving 690 lbs fuel a hr in at our new target. Now we've driven the BSFC down to .726. Lets say all that extra fuel is suppressing detonation well and we give it 2 degrees of timing and hp goes up to 1050 , now our BSFC for sake of discussion is .657, this is a over simplified example but it gives you a idea.
so in your case if you have a extra safe tune/conservative timing i would take a guess at your BSFC being .700. if your using 614 lbs fuel per hr, would put your hp at about 900 ( 614 /.700). If your bsfc is .650, would put your hp at about 950 (614/.65)..
Now this also all based on your CALCULATED lbs per hr that Holley is telling you. So theres alot of assumptions there too, the specific gravity of the fuel your using , the amount of ethanol, the actual fuel pressure it has and what the injectors actual flow compared to what holley calculates they flow , it says your using 614 lbs a hr, you could be using 550, you could be using 680. But it does give you a basic idea, Smitty


All times are GMT -5. The time now is 10:16 AM.


Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.