If cast ron heads flowed the same as the Aluminum heads...
How much more power would the cast iron heads make???
This is a thermodynamics question..
It's a "heat" engine correct???
Just for curiosity sake how about sharing the static compression ratio on that 503 cu. in. engine that made 800HP+ with those nice heads, and by the way, what was the rpm the peak horsepower was measured at, what was the camshaft size specs. and what octane gas or fuel was required??
Ray @ Raylar
6800 RPM with pump gas. We generally uses 92-94 gas to be safe, the CR is 9.35 to 1. Our combination is not really the point...the point is these cast iron heads flow enough air to support 800+ HP. Someone else might rather use 540+ CI and use less lift and/or less RPM. What is important is the small intake port can make the power with greater velocity for kick in the pants acceleration. Our 50-80 MPH acceleration time is just a tad above 7 sec....I think! I can post the numbers tomorrow if you want to know the exact time.
No personal testing proof, but it seems to me many set up the valve train without sufficient lift to take advantage of the increased air flow from a good set of BBC heads between .650to .700 lift.
Most of what you asked is in the last post. Cam spec info belongs to Mike Riley, MRE Power Products. I am pretty you saw this engine at the PRI show 2007 and we met at the MRE booth. The 55 mm cam has a reasonable duration with a 420 cam lobe with 1.8 & 1.75 rocker ratio. I would rather you talk to Mike if you want more info. I can post the exact results if needed, but we made a little over 800 HP @ 6800 RPM with CMI 1-7/8 ID Sport Tubes...and 820 HP with 2.25" full length dyno headers.
Thanks for the numbers and info BEN and I think its very doable for a 503 at those rpms with that fuel and compression ratio to make over 800HP+, because the camshaft is so big in duration and lift that the average performance boat wet exhaust system would revert like gang busters. That puppies gotta have duration number up around 270-280 @.050 on the intake even with the best flowing head to get anywhere near those rpms for peak power and the torque peak is gonna be up where most average performance boaters never even go for rpms.
This is my point that sometimes here on OSO, we've got to kinda keep in mind that most of the readers and average boaters are running performance boats where 5200 -5600 rpms will be their average high rpm range, 89-91 Octane fuel will be the marine and average gas station fuel they will be using and very few of them will be running valve trains and Jesel drives in their engines that can sustain these kind of 6800 rpm peak power points. What you are really describing here is an all out race engine that would cost the average performance boater $25-$40K for the whole package including the fuel system, bottom end, rotating assembly and such it would take to produce an anywhere near long life (400-600hours)reliable marine performance recreational engine.
This is not even counting the 850rpm+ idle that puppy is gonna need with a cam big enough to feed it at 6800rpms and what that would do to the average Bravo drive at shift time.
Not to bash anybodies engine developemnt or project, but lets be careful to describe the beast completely so our not so knowledgeable readers can understand what something like this really is when we throw these horsepower numbers around.
Just my 2 cents again, as I hope most of the time I speak to the average "JOE PERFORMANCE BOATER"
sorry, you "OVER THE TOP BOATERS" get all the attention you crave and need.
Ray @ Raylar
You are incorrect on the cam...ours is much smaller. The design is based around the the old class spec's for APBA engine A-B Class engine but today it could be built at a price point for a lot less than some "major" engine builders would sell you a 600-700 HP engine.
Builders like Tyler Crocket, Dean Gellner, Keith Eickert, Mike Riley, etc have and can build this combination.
As to drives, in my experience what breaks Bravo's is the torque related to big CI (540-572) not the HP. We run our boat hard and the only Bravo Drive failure we have ever had in the last 15 yrs was in the the late 90's when the stock Mercury top cap broke on the port drive....prior to today's after market cap options.
Is $40,000 for a bullet proof fully rigged BBC marine engine too many $ ? Compared to what? This exact same combination could provide 700+ HP @ 6000 RPM or 650 HP at 5500 RPM. We elect to use premium gas, but we could not detect any detonation on the dyno with 89 octane.
Ray, I respect what you have accomplished, but in the market you compete in and sell to, I perceive you need to be fairly conservative, maybe driven by the warranties. Many OSO's just take our chances and focus on improvement.
Thank you for the compliment, my compliments to you on your engine package! The best of continuing success to you!
You are right in that this type of engine is very feasible, just not practical for the average performance boater.
When one uses a race type engine setup like this in the average recrational performance boat it would be a recipe for disaster as far as endurance goes and being user friendly at cruise rpms and idling. As for the standard Bravo drives I know from hundreds of inputs from users that an engine you describe making about 700 ftlbs of torque at those HP numbers and with those rpms around 6000 or so, it's gonna be a short trip for the average Bravo in a heavier performance boat in bigger water than average Texas lake water!
I wana see the Bravo drive that can go 15 years behind this motor, cause I am gonna buy a boat load of em and make some good money!
I realize that a few OSO'ers like to push the envelope of engine and drive performance and its this push that yields some great performance and racing results. The problem is I have yet to see or meet any quantity of these boats that can run 400-600Hrs without serious rework, rebuild and constant garage and dockside tweeking to keep them running season to season. If you've got such an animal, yes then at $30-$40K they should sell like HOTCAKES!
Keep in mind the performance boating market for both boats and engine and drive packages is like a tiered pyramid. At the very tippity top you've got this 5% or so group of buyer-users who can afford almost any package and any amount of upkeep and rework. But under that 5% tip you got the 95% of the market mass who does not have the wallet, knowledge, patience or expertise to own and operate these kinds of boats and mills! I can't stay in business and make a profit selling to that 5% part of the pyramid, I gotta stay down here with the other 95%!
Raylar's got some pretty incredible engine packages like our HO750 and such, we just can't stay in business, especially in Todays Economy selling just these type of engines, We'd starve if we tried and everybody at our Funeral would Say:
"Those Raylar Guys Did some Cool Stuff!"
Ray @ Raylar
Ben Perfected I would really be interested in talking with your engine builder about this package. Can you forward me his information.
This is our engine bldrs contact info:
MRE Power Products
Alum Metal Fab
Custom Marine Sales
Dave's Custom Boats
Diamond Performance Parts
Double R Performance
Elton Porter Insurance
Fastboats Marine Group
GGB Exhaust Technologies
Grand Sports Center
Ilmor High Performance Marine
Lake Cumberland Marine
Lake Havasu Boat Show
Marine Technology Inc
McLeod Design Group
Performance Boat Center
Performance Marine Trading
Potter Performance Engines
Ron Sporl Performance
Speed and Custom Marine
Total Dollar Insurance
Teague Custom Marine
Wake Zone Marine Insurance
Young Performance Marine