phughes69

stock bore 454 LS6 short block
original Gale Banks Mercruiser twin turbo engines
draw thru carburetor
Inter-cooled with waste gates making 15 PSI
7.5 comp ratio
Hydraulic flat tappet cam
about 5200 RPMs

I took the old heads to the machine shop and found out the exhaust seat was cracked and one head needed 2 guides. The heads are 188 castings w/o seat inserts.
I'm looking at Iron Merlin's that have 345 CC runners and wonder if they are a good fit for my combo.

FIXX

iTrader: (2)

as long as you are forceing all that air through their it should be fine..but i think you will be spinning more r's then the target rpm's posted. they will only flow 345cc @ the specific lift of the cam..in other words they will flow 345cc's @ lets say .600 lift..if your cam lift is .550 then they will flow less.

jeffswav

I would like to see a pic of that turbo setup. Sounds pretty cool, did not no merc & banks every got together.

GPM

Probably a bit lazy until you start making boost. Aluminum may be better for detination.

phughes69

I would love to do aluminum heads, but it is not in the budget for 2 engines, unless someone can point me in the direction of some that already have inconel exhaust valves.

cubicinches

345 is the runner volume in cubic centimeters, not the airflow.
An iron 345 Merlin flows something like 370-380 CFM @ .700 lift. Not an overly impressive cylinder head, but should be fine with the turbo.

SINGLETGT

The turbo's will spool faster with a smaller cc chamber on the exhaust side. Doing the swap will allow you more effiecient hp, but power might come on a little later because now those little turbos would have to FILL those chambers/runners with air/fuel before you got boost. Also, boost is just a measurement of a restriction. Its all about the flow of the motor. If I was you, I'd have someone plug up those exhaust weep holes in the housings and run some external wastegates. The benefits from this will be a less laggy spoolup and adjustable boost.

Make sure you retune the motor after you swap anything! Just because it was spot on at (for arguements sake) 6psi before, that doesn't mean it will be anywhere in the ballpark @ 6psi on a better flowing motor! The carbs are metering for cfm..