Change of Engine Plans?
 

I am currently running a well tuned/dialed in 468 EFI with a Procharger (as most of you know). Good dyno numbers, checked at two seperate shops indicated a true 638 HP.

I was in the process of collecting parts for a 700-750 HP, NA, EFI engine and purchased an Arizona Speed & Marine Modified 500 HP intake (oval ports), an ASM Large Bore throttle body and 55# Bosh injectors. This was to be the fuel system for a 572 tall deck with aluminum heads.

Several sources have recommended not building a large CI, NA engine and simply recommended stroking my engine or building a simple 540 and installing my blower, accessories etc. on it.

My boat is just shy of 80 MPH currently and the extra
70 - 100 HP would get me right where I want to be.

What would you do to obtain the 700 - 750 Hp result?

Re: Change of Engine Plans?
 

If you build your 468 into a 540 it is a 15% increase and your 638HP goes to +15% = 734HP and you are there. Send your current heads to JimV and up the cam a little.

Re: Change of Engine Plans?
 

also... and i am suggesting this knowing absolutely nothing about your boat specically.... i would look carefully at " where you want to be" vs the hp you THINK you need to get there. on my 38 ciggarette to get from 65 to 70 if i remember the calculations . was going to be something on the order of another 125 hp per motor.... and because the drag is the cube of the speed, YOUR drag numbers at 80 are going to be much higher.... all im suggesting is that you do a bit of research to confirm your estimates... i think you are going to need a LOT more than the 100 - 150 you are talking about to get a meaningful increase... and by research, i mean actual calculations... not anecdotal...

there are a couple threads floating around that dealt with this that were very good that had my numbers and calculations as well as a couple of sites that had calculators built in...

Re: Change of Engine Plans?
 

Steve,these panteras are like velocitys,they go pretty fast without a ton of power. My Baja 272 took around 725hp to go 80 mph where pantera28's boat runs 80 with 638. It took over 900 to get my boat into the 90's where it will probably only take 750 to get his there,the hulls pretty effiecient but you do have a valid point in most cases,Smitty

Re: Change of Engine Plans?
 

I would agree with Cobra Marty. That seems like the most economical way to get a meaningful horsepower increase. Just going to a 572 n/a would require a good ( read expensive ) set of aftermarket heads to get 700+ hp. By reusing your Procharger and induction, all you really need is a 540 short block.

Re: Change of Engine Plans?
 

Why not put the bigger injectors in your current motor and turn up the boost or are you at the limit already,Smitty

Re: Change of Engine Plans?
 

I already purchased and have the larger injectors. My boost is only at 5 psi. Maybe a 540 with the Procharger is the way to go.

Steel or Aluminum Heads? I have Dart heads now.

Re: Change of Engine Plans?
 

Your dart iron heads if unported barely flow over 200 cfm on the exaust side,a good set of aluminum heads flow 300 plus on exhaust side. If you want to make serious power a set of well flowing heads should be on your agenda . If your motor is making 635 hp at 5 psi of boost using some crude math (ignoring the parasitic loss of your blower and alot of other small details) lets say 14.7 psi of boost (twice atmosperic pressure) would give you a 100 % hp gain over base power,5 psi is close to 1/3 of that so lets say blower is adding 33% of your power. That would put your motor minus blower at 435 hp,probably close to what a dart headed 454 would make. If you turned your boost up to 9-10 psi you should gain 66% over your base number which puts you around 725 hp,the number your looking for. As long as your 454 is solid why not install your bigger injectors and crank up the boost? I have ran my 502 and 540 at 10 psi of boost (with aw504 innercooler) on 93 octane with no detonation or over heating. The plus side when you drop pulley size is torque comes in real quick and early. Remember-boost is your friend :evilb: ,Smitty

Re: Change of Engine Plans?
 

My 454 is built very well internally.

The thought of running boost so high scares the hell out of me!!! I don't know why, but it does. Maybe an upgrade to aluminum ported heads, shaft rockers and an increase in boost is the way I should go.

Is the AW504 a larger cooler?

Re: Change of Engine Plans?
 

The aw504 is the 504 sq inch innercooler procharger sells with most m-3 sc kits,its a option with the m-1. With a innercooler 5psi of boost is VERY conservative,I have ran my 502 and 540 between 8.5 to 11psi of boost on pump gas for a total of 330 hours without ever blowing a head gasket,melting a piston or any other high boost related casualty,i just use felpros too but with aftermarket heads and studs,you will be fine turning it up,especially since you have tuning and monitering capabilities for your efi system,Smitty