[Roadsters] Head Porting

[Keith0alan at aol.com]

In a message dated 7/9/2008 8:51:46 PM Pacific Daylight Time,  
drlsmith at dccnet.com writes:


Now  to be fair, part of the reason, I think, for having less detonation is
that  the longer duration cam will also reduce the effective compression  
ratio.

And something that really bothers me, after spending nearly  $2,000 on a cam,
lifters, cam gears, porting gaskets etc. they gained only  14 hp at the 
wheels!
Up from 64 to 78........

My hopes of getting  100 hp at the wheels of my 1800cc stroker are looking
pretty damn  slim.......  :-(

Daryl



A longer duration cam will lower the effective compression ratio. I think I  
might have milled the head a bit to pick the compression back up into the  
premimum range. Also, torque is generated by combustion chamber pressure, HP is  
generated by RPM. You can increase chamber pressure to increase torque and 
bump  HP some but the real HP increase comes from higher RPM. Rather than the 
stock  6000 RPM, build the engine to do 8000 RPM. With no increase in chamber 
pressure  you will pick up 1/3 more HP. This sounds simple however there is a lot 
that  goes into moving the peak of the torque curve from 6000 to 8000. Cam, 
port  sizes, balancing, strong rods, oiling and on and on. If you do the port 
and cam  to peak at 8000 rpm then only run to 6000 rpm you have wasted a lot of 
time and  money. You will see some gains but not nearly what you could.
 
Enough rambling for early in the morning.
 
keith



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