is the 113 cchead a closed chamber head?---if so, a flat top piston will give you around 9.5 compression or so---almost every pison manufacturer makes one---will run pump premium easily and work well for a lake motor---you can still run a bump stick and some carbs and get some decent performance---mine ran 75mph thru the lights on that kind of setup in a heavy hondo flat
All the heads I have are open chamber. I have 5 sets. eek!
I was trying to find a TRW piston that was a little less money. The motor will be for my 73 Nordic. It is a very heavy boat. I went with the 427 crank because its a forged crank. Now im wondering I should have stuck with my cast 454 crank.I still have the 454 crank but I already had the 427 turned. 454 pistons are very easy to find in any compression.
TRW Piston #L-2268F30. Compression ratio 9.99 to 1 with 119cc head. $41.95 each. Summit link here:
http://store.summitracing.com/defaul...3D1%26s%3D 182
Speed Pro...same as TRW. Dome is solid. Turn the dome down in a lathe to lower compression if desired. No big deal.
[ March 24, 2003, 06:39 PM: Message edited by: Fiat48 ]
I'm running the .585 dome TRW slugs in my 427 with the 781 casting heads. I had to enlarge a corner of the combustion chamber where it was contacting the piston domes but other than that I've has no problems running 92 octane at 38 degrees advance.
Dans66Stevens:
The problem is that those pistons all put me around 11 to 1 compression. That is to much. Im not even sure if 10 to 1 is going to be ok.
(Am I correct in thinking 10 to 1 is all I can run with pump gas?) Dan,
In regards to compression ratio vs. pump gas, here's something nobody has touched on:
The cam profile is an important factor in bleeding off cylinder pressure. What I mean is that mechanical compression ratio alone doesn't determine what octane fuel you will need in order to resist detonation. A more radical camshaft's duration, overlap, etc. allows more cylinder pressure to bleed off before the valves are closed and the air/fuel mixture is compressed. This is one of the reasons we raise compression--to compensate for loss of cylinder pressure due to increased cam duration...
Other factors such as ignition timing, jetting, altitude/atmospheric condition and even the grade (quality) of fuel (to name a few) will factor into whether or not you will be okay with pump gas.
All the components in you engine work together; therefore, if you want to be able to run pump gas, keep in mind that every time you choose a component to be used in your new engine that, to some varying degree, it also will affect what kind of fuel you will need to run.
LO
[ March 26, 2003, 08:02 PM: Message edited by: LakesOnly ]
[ March 26, 2003, 10:09 PM: Message edited by: Fiat48 ]
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