Hot Boat

I am looking to build a 502 this winter. I want to use most of the parts from my 454 with a 177 blower & inter cooler except the pistons and rods.

My 177 blower with inter cooler pushes 6 psi of boost on the 454 with 8.9:1 pistons.

is it possible for that blower to build 5 psi on a 502 with 8.5 flat top pistons ?????


There isn't enough room to fit a 6-71 or 8-71 or I would. The pulley on the 177 is only 1" from the fire wall. I am also on a budget so I would like to work with what I got if I can.


Also I found the motor in the classifieds,

http://www.offshoreonly.com/esvon/page-12426.html

Its similar to what I am looking to build , Less the inter cooler . He says they are 667 Hp. Is that possible. and if so could I get about 700 HP with the inter cooler on that setup?

nordic95

Call Roccard Marine,He will set you up.

Nordic95

Pure Energy

Doesn't he make 750 HP with that combo??

Give JC a call, I'm sure he'll help you out.

SB

iTrader: (1)

5-7 psi with that blower on a 502 with OE heads will be a reality. You'll be spinning it pretty hard, not as effecient as a bigger blower, but will be okay.

I feel an intercooler will be a must at this level.

Get good valves, headgaskets, bolts/studs, etc.

700hp will really be pushing that little blower.

If you have an intercooler as stated, why wouldn't you be re-using it ?

mcollinstn

I don't think you'll see 700 horses out of the 177 on pump gas.
You're facing the upper end of the curve right now. All roots blowers have an efficiency curve plotted with rotor speed against airflow. The faster you spin those rotors, the more heat you whip into the air. The more pressure you create with it, the more heat you squeeze into the air.

You can still make 5 or 6 psi on a 502, but it will be a hotter, less dense charge with more parasitic drag at the pulleys (than a properly sized blower). So make sure the intercooler is getting good water flow.

And 700 horses is really pushing it.

Hot Boat

700 Hp is pushing it , That what I thought . I will be sure to use the inter cooler. With the current set up i get 10 - 13 psi on the inter cooler with 1/2" hose in and out I assume that's good.

How about a 250 blower with inter cooler Is that much better. I think that will fit under the hatch.

mcollinstn

A 250 Blower will get you where you want to go, but barely. It will also take 7 pounds of boost, some head work, bigger valves (and inconel exhausts if you want em to last), and a good cam/lifter/spring combo.

KAAMA

iTrader: (1)

A few years ago I remember JimV showing me a dyno sheet of a 454cid marine engine he did back around 1995 or so with a B&M 250 blower, GM rectangle port heads with some port work, a single carb and with 5-6 pounds of boost it made something like 623hp @5600rpm on Tom Earhart's dyno with an Ultradyne 231*/239* flat tappet hydraulic cam. Which was actually the cam that Merc used in their old 454cid/440HP cyclone engine from about the early to mid 1980's.

That was years ago. Technology has come a long way since then...it's hard to say, but perhaps it may have made more/better power with a smaller cam. (?????)

VP

I also agree with trying to get 700 hp with a 177. Probably not going to happen.

I had a 468 (.030" over 454) with a 177 blower running about 5 psi boost. It ran fantastic.

Then after breaking a rod in the ole girl, I built a 540 CID using a new Merlin Tall deck block etc., thinking bigger is better. I re-used my same rectangular port heads, Weiand intake and 177 blower (limited budget also). The compression ended up at 8.98:1 with flat tops (bigger dispacement makes bigger compression fast). It dyno'd at 624 hp at 5500 rpm, with 700 drive busting ft-lbs of torque at 4000 rpm, because of the little blower. The boost went as high as almost 5 psi at 4500 rpm but then dropped off to 4 at 5500 rpm.

Bottom line was, it didn't run much better than the 177 on the 468. That was a good combination. You can try cranking the boost up a liittle on the 454 and make really good power. You also need to put as much timing in as possible (ie: at least 30 degrees). With an intercooler, you can do that easily - probably 34 - 35 degrees is where you want to be.

topfuel

Hot Boat, if you're interested, I have a 250 with intercooler that is available. Send me a PM for the detail is interested.