Rebuilding volvo 5.7 chev engine

Hello everyone
I am thinking about building a new motor for my 26 FT. HOURSTON
I would be starting off with a marine block that has the one piece rear main.
New pistons D shaped for the quenching effect as per Ricardos recommendation.
Here is my question I am considering using aluminum chev fast burn heads
for increased power.
I will be using closed loop cooling system with heat exchanger
Will the salt air environment cause havoc on the aluminum heads.
Or should I just stay with the cast steel Vortec heads
Thank You in Advance
Cheers

The GM SBC Part Number 12464298 fast burn aluminum cylinder head chambers offer a similar quench surface "point" as with the cast iron Vortec heads.
According to the specs, the chamber volume is 62cc, of which creates the need for a dished piston in order to achieve the correct static C/R for Marine Cruiser use.


If I were doing this, I'd choose a piston profile (w/ a quench surface) that mirrored the cylinder head's quench surface "point".
The D shaped piston would not mirror as well as a LCQ style profile would.

I would keep the valve spring pressure minimal, as there's no need for high spring pressure for this lower RPM engine.

According to some, the static C/R can be bumped up a bit with the fast burn aluminum cylinder heads.

The added ignition advance (from that of OEM Marine specs) will help create the proper LPCP, of which will give this engine better torque.



As for the dissimilar metal corrosion aspects, a Closed Cooling system would be mandatory, IMO.





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Hi Rick, Thank you for answering all my questions. That was very helpful. I will consider using the aluminum heads as apposed to the vortec heads. I need to know approximately how many more horse power I would be gaining using the aluminum heads over the vortec heads.

Cheers

zapper1 said:

Hi Rick, Thank you for answering all my questions. That was very helpful. I will consider using the aluminum heads as apposed to the vortec heads. I need to know approximately how many more horse power I would be gaining using the aluminum heads over the vortec heads.

Cheers

Click to expand...

We are after Torque..... not necessarily horse power.
With a good fairly tight quench dimension, we can increase our ignition TA.
When we increase ignition TA, while avoiding Detonation, we end up with a better LPCP.
Most Engineers will suggest that LPCP is most desireable when it nears 12 to 14 degrees ATDC.

For even better torque (and horse power), you could build yourself a Q/E 6.2L or 6.3L SBC.

6.2L = standard bore w/ 3.750" stroke....... 377 cu in
6.3L = .030" over bore w/ 3.750" stroke....... 383 cu in


Just to toss this in the mix here:

Given two identical boats...... a standard SBC with a Duo Prop drive will generally out-perform a good Q/E SBC with a single prop drive.




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Hi Rick
I have come to the conclusion that I will build a stroker engine with cast vortec heads.
I am having problems with finding the correct piston for my application.
Any help with this would be greatly appreciated
The cam that I am considering is lift .431 intake/451 exhaust, duration @ .050 196* intake 206* exhaust
What are your thoughts

Take your "knowns" and plug them into one of these online C/R Calculators.

http://www.summitracing.com/expertadviceandnews/calcsandtools/compression-calculator

http://www.gtsparkplugs.com/CompRatioCalc.html

http://www.diamondracing.net/tools/


Enter the cylinder head combustion chamber volume..... (I believe that the GM cast iron Vortec chamber volumes range between 64cc and 65cc.)


You will vary the compressed head gasket thickness once you determine a piston deck height dimension.
(Quench dimension will be close to .038" to .042" for the Marine build.)

You will want to use a Q/E style piston, of which the profile will be dished.... so enter a dish volume value.
(vary this volume until you come up with a suitable Static C/R.)


I would stay with the standard rod length and piston skirt length for the Marine version.


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