Ring Gap

-
If u use nitrous, plenty of gap, more gap is directly proportional to the amount of N20 used. Research it.
 
Gotcha. Obviously I will check with the piston manufacturer but what would you recommend for the 2nd comp ring gap? Mine seemed a bit tight. Around .022ish. Seems tight to me. Thoughts
I can't remember but I gapped my second ring at it's widest recommended gap setting. I had read an article (doesn't mean it's true ) that they purposely over gapped KB 2nd ring and found no compression loss or oil usage. I agree a little more gap is better than not enough.
 
Yea I know. The machinist told me that as well. This motor will be a NA motor for my daily driver. Will not be beating on it
If you insist on small gaps, you better make sure that your cooling system is well able to get rid of heat, and that includes getting your PART THROTTLE Timing right.
The engine does not have to working at WOT, to be making heat. In fact, most overheating problems begin at under 30 mph.
I went down the road you are embarking on, only to have to pull the engine back out, and increase the ring-gaps.
I think I know what you might be trying to do, but it is all too easy for it to backfire on you. If you really really want to keep the pressure in the chambers, there are better ways to do it then with tight gaps.
Of all the energy in the fuel;
about 1/3 of it goes out the tailpipe as hot gasses, and
about 1/3 of it goes into the cooling system, and
only ~1/3 of it eventually gets to the crankshaft.

You can't do much about what goes out the tailpipe, except to make sure your ignition and carburation systems are as optimized as you can make them.
If the Cooling System is working, you can't do much at all with it.
Whereas;
Power comes from the heat in the expanding gasses.
To make the heat, yeah, you can try and contain it in the chamber, and capture as much pressure as you can, but a better idea, IMO, is to just start with more pressure in the first place. Which means as much cylinder pressure as your gas will support.
As for fuel economy in a city car;
most of your fuel will be burned up during the acceleration phase, especially with an Auto trans. Typically, city fuel usage is double or more, of hiway useage.
And finally. At the price of gas today, Economy should be figured in Cost per mile NOT miles per gallon.
What I mean is if the cost difference from 87 gas to 91 gas is 10%, but your hi-compression engine gets 11% better fuel mileage than a lo-compression version; then you are still money ahead with the higher compression
This is even more true with a DD type engine.
For a small V8 engine that never sees more demand than say 300cfm, a well designed unit can run a lot of static compression ratio without detonation. (Detonation must be avoided at all costs.) And with such a design, your ring gaps can be , might have to be, much larger
The higher cylinder pressure is gonna make more heat, equals more power = less throttle opening for a given roadspeed = less fuel consumed over a given distance.
This is especially important during the acceleration phase when getting up to speed.
I can almost guarantee you that in a city car, you will never measure a fuel-economy difference between ring gaps of .026 and .032. But you will, with just 5% more cylinder pressure, so long as the engine stays out of detonation, and the cooling system is up to the task.
 
A 'good' cooling system will actually make a small ring gap problem worse, could cause end-butting.
A block that runs too cool does not expand as much,
 
-
Back
Top