Quote:
Originally Posted by Platinum_Racing
Another good idea is to get the blocks deck ground down. This will increase the compression ratio and squeeze some more ponies out of the motor.
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You can't remove much from the deck. Not enough to make a noticeable increase in power. The stock GA16 pistons are nearly flush with the deck, so milling off too much will result in piston-to-chamber contact.
If you want more compression, go with custom high compression pistons. I had some custom 10.5:1 pistons made years ago by Venolia. They were still slightly dished BTW, so you can imagine that with domes you can get substantial compression increases. 13:1 would be easy, but you'd need supporting mods to work with that.
11:1 could be used and still tolerate pump gas,
if you had cams to go with it (the increased overlap would negate some of the cylinder pressure increases from the high compression). We ran the 10.5:1 compression with pump gas and modest cams, plus 5° more baseline timing and it never pinged. The combustion chamber design seems to be extremely knock-resistant.
IMO, the best places to make power with the GA16DE are:
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Professional head work, concentrating on the head's poor exhaust flow characteristics. Bigger (custom) valves, although expensive, would wake this engine right up.
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Cams. Even the Jim Wolf cams are pretty darn tame. There's a
lot of power potential with appropriate cam profiles, probably somewhere on the order of .425"-.440" lift and 240° @ .050" duration (about 280-290° advertised depending on the lobe's profile).
About 6 months ago I helped a friend out with a Subaru EG33 engine. Had some cams custom welded and ground, and I ported the heads. The engine picked up 71
whp with no other changes. I think this shows that most production cams are
extremely modest. Those stock Subaru cams were .280" lift and 198° @ .050", we went with .450" lift and 244° @ .050" duration. It literally added almost 2000 rpms of usable powerband to the engine (revving to 8200 rpms).
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Compression ratio increase...works in conjunction with and compliments the cam upgrade.
*Proper
4-into-1 long tube header and good exhaust system.
FWIW, you'll never make really strong power increases with modest bolt ons with this engine. Gotta go custom at some point. It's not a bad engine design, but we have to remember it was designed as a cheap, mass-produced
economy car engine. Nothing else, no aspirations of FIA domination, just a grocery-getter.
Bob
but you seem to know alot of the unasked questions.
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