No worries KAAMA, I am learning also. The more information the better:)

Hey Rob, is there any particular reason 850HP is your number? Only reason I ask, is because I think you would be pleasantly surprised even if you were only 750HP per side with your new setup. You should pick up some speed considering your drives are not mounted in the basement any more. Sometimes just getting the drive height dialed in is like adding 100hp a motor.

With 8:1, iron heads, no chiller, I'd keep the boost at 6, maybe 7psi if the tune is right. I think you'd be making a honest 750HP per side, and boat would probably run really nice. Blower motors make some impressive torque, that will put a smile on your face! My buddy did some 509's, that did 800HP, but he had a chiller, and I think they were around 9-10psi on the dyno.

Granted a different boat, but a buddy of mine has a 1990 Top Gun with a pair of 800s. Konrad drives mounted about 4" or so below the bottom. Pretty much runs mid 80's. I'd expect your boat to run about the same #'s with 750s. To get to 100mph, you'll probably need a pair of 1000's, maybe 1100's.

Stick with iron heads for longevity, and chillers for that bit of extra cusion. 850 will be an easy target to hit with the right setup, and still be reliable on the pump gas ya get around the dock. NOT installing chillers just doesn't make sence to me. That extra insurance against detonation is well worth it when compared to the damage that can be caused if it happens.


Darrell.

Since we are on the subject, lets talk about chillers for a minute. This is a subject that comes up often between a buddy and me over beers. He runs a 9:1 iron headed 8-71 509CI with chillers. His plan is to increase boost to 8psi.

So, if we compare two builds Lets say you have one engine and you want to run 7-8psi.

502CI, 9:1, iron heads, a basic build and you put a 10-71 on it.

502CI, 8:5:1, aluminum heads, properly selected blower cam, proper steps taken in the build for a good quench, polished combustion chambers, and bolt a 10-71 on it, no chiller.

Now, with both of the above setups, running say 7psi, and the blower is underdriven, since we know overdriving creates alot of heat. It is understood that compressing air in itself raises the air temperature, but how much at a level of 7psi? And which engine would have a larger safety factor from detonation? The aluminum headed lower compression blower specific build, or the iron headed higher compression intercooled setup?

Im pretty sure that the intercooler helps alot with a mini blower, like on a 177 or 250 blower driven at say 2:1 ratio. Im sure the air temps after the blower can get quite hot. But how much heat would be generated by a bigger blower running at say 10% underdriven? Is there enough heat in the intake air temp to allow the chiller to make a substantial drop in temperature?

I know that in say my Semi truck, I have a intercooler, well, a air to air cooler. However, at full load and wot, I peg the boost gauge at 32PSI. Or like the guys who run Turbo Buick Grand Nationals, with intercoolers and 18+lbs of boost. I can definitly see the need to cool the air when it's compressed to those levels. Granted its probably not the heat generated by the compressor itself, but the heat from the compressed air.

Even if with the above 10-71 setups, detonation wasnt a issue, how much power would be gained/lost with a intercooler. I've seen where some have lost speed when adding a chiller, so they overdrive the blower a bit more , to get it back. And i've also seen where turning the water feed on to the intercooler on the dyno netted about 20hp with no other changes. However, i'd be curious to see if that 20hp would come back if he had removed the chiller completely, as to not have that restriction in the intake.

DMOORE, the only reasons i can see not to run a chilller, would be cost, clearance issues, and if you sprung a leak in the core and filled the engine with water.

Reasons i can see you NEED a chiller, would be increased boost levels desired, small compressor overdriven, higher static compression, lower octane fuel, iron heads, or when running water thermostats or boating in very warm waters.

I know lots of guys running roots blown stuff without chillers and no issues, and i know lots of guys running roots blown stuff with chillers, and no issues. I guess it comes down to the overall build and how its setup. Would love to hear some proffessional input on this topic! Just another think to talk about over some beers!

I figure if I am going to go through all the extra cost of blower kits, fuel systems, oil systems, not to mention ALL the money I just spent on transmissions, drives, and hydraulic steering to handle all this extra power! I might as well make as much SAFE horsepower as possible from my 509 cubic inches! Also 750 from some big roots style blower motors, just seems a little on the weak side. I am the type of person, that if I am going to do something, I am going to do it to the best of my ability, and make the most of it. Kind of a go big or go home attitude. Keep this debate going guys, I am learning alot as I am sure others are as well. The goal one day is 100 mph, so maybe I should be thinking 10-71's with chillers, that way when I take the bottom ends to 588's or something similiar, I can make that 1000hp from the same blower package that I run on the 509's, and not have to upgrade the blower's again down the road? I have already my wife thinking about the reality of some blower scoops coming through her tanning bed:)

What blocks? I would not recommend aluminum heads on a GM 502 with that much boost...or anything past 750hp with those blocks.

Why is that?

These engine's started life as carb hp 500's. Are these blocks not going to take that much horsepower? This would be the first I have heard on this topic. Also why no aluminum heads on this block at that boost level? I do plan on staying with the iron's, but I am wondering about the logic on that as well?

a custom 10:71 will fit, call Littlefield and tell him you want the blower with more forward bias, this will allow suffiecient distributor clearance, and you can run 10% under which will give you a lower charge air temp and still make plenty of boost... run a roller cam that has around 250 deg duration @ .050 on a 114 grind, with 8.0:1 compression, she will live and you'll be a happy camper!!

BTW my 10:71 package w chillers is for sale...:evilb:

and with 588's you will make in the neighborhood of 900ish hp and be safe it the charge air department...

hey mild thunder a chiller does two things to air, its cools it, thus condensing it (shrink) and as a result, lowers boost, also intercoolers tend to be restrictive in nature as the air has to pass thru the core... that being said, lets not miss the true point here, the benifit of the chiller is that it allows you to run the blower much faster without the risk of detonation, this equals higher torque and horsepower (net)

If they were 500's then you'll need way better cranks and most definatily better rods + pistons also.
Because most aluminum heads will lift off the decks on 502's at that cylinder pressure....800-850hp.

head studs will help as well as a good gasket, but ultimately you would need a good block, with the right rotating assembly... bowtie race block, or merlin...

Okay so forged eagle cranks, forged je pistons, and forged gm rods are not going to make it to the 800-850 range? I do plan on running the iron heads, and the motor is built with arp bolts now, and real good head gaskets. I realize those will have to be new when we do some more work on the heads before the blowers go on. What hp level can my bottoms ends live at? I thought I had read lot's of story's of people strapping some big stuffers on there 500's and having them live at the 800 mark? (the only stock part in my bottom ends are the rod's themselve's)

Will be twisted into pretzels under that kind of torque.

But I like the way you are thinking.....New Power and drives.

Bullsh*t ...

hey Rob give me a call, I'm avail in the evening for consults, I can be reached at (905)722-6684 Alan K
www.akracing.ca
sounds like you need some professional advice, I can help

hey Rob give me a call, I'm avail in the evening for consults, I can be reached at (905)722-6684 Alan K
www.akracing.ca
sounds like you need some professional advice, I can help

Hey Jason, being patient is not best quality, but I actually am buidling the rest of the boat to handle the new power before I tear a bunch of stuff up. Big shaft #4's already hanging off of the back, and huber 1350 transmissons as well.

Alan I appreciate the offer, I actually grew up in southern Ontario. The 905 area code looks familiar:) I have a very busy week but will give you a shout next week for sure.

With a proper tune and no detonation, that set up will last for years at that power level. I have over 200hrs on my 502's, and they have't missed a beat.


Darrell.

Are you running the GM dimple rods Darrell? What RPM you turnin? If I remember right you have 600sc blowers (420 B&M) with chillers? 200 hours is good stuff.

No problem. The journals on the Eagle cranks aren't always sized 100% and usually need a polish, but if your machinist has already taken care of that then I wouldn't hesitate to run them. They're more then strong enough for your application. The rods will be fine too as long as they have good bolts.

I agree, I've made over 1000 HP on that "stuff" and never had issue, once again, the secret is in the prep... if your engine builder knows what he's doing, then once proper clearance is established you will be fine!!!

The internals are the stock SC 600 parts. Mine are 98's, which for some reason, are listed as a one year motor. They have the 91-94, then the 98 . Not sure of the differences between the older SC 600's and the 98 model year???? But I assume it has the GM rods as well. The motors have had msd ignitions installed and spin to 6000 rpm's. I couldn't be happier.



Darrell.

Good stuff. According to the merc parts site, the 1998 600sc had the same gm rods used in the HP500 and others.

sorry... speed girl

hey kamma... you still have those 14:71's?

Thanks for the offer, but my builder said the 14:71's will work.....and work well with my 557's. He's my builder and I trust him. I'm going to stick with what he says and hang on to the 14-71's.

With that....My advice would be 8-71's with 750's at no more than 7psi with roller cams. Should put you at about a tick under 700hp at 5500 and be happy.
Marine motors need a big safety factory built in over street motors.
A fraction of a second of ping can junk a motor with less than the right internals. If you want that 800-850 your going to need some good stuff.... Merlin or Dart with American made cranks and I or H beam rods, etc.
Happy boating and be safe.

As stated Eagle crank's are known to be on the large size . And going as far as you are I would buy a good set of steel rods , they will be the best money spent . Just my .02 good luck with your project

Bringing this one back around, So what was the conclusion with the 14:71 s on the 557 motors?