Gas ports in pistons

What are your opinions on Gas ports in pistons? Do they actually work? If they work, how much HP gain? Is a gapless top ring nessessary in this application?

gas ports.........lose the gapless crap......... .043 top...........vacuum pump.........you betcha.

X2

Charlie

I'm curious about this as well. I understand the theory of the gas ports is to help with ring sealing at higher rpms, but at what point would it be wise to get your pistons done? I'm building a 466 motor for my all out bog truck, and it will see occasional hits of NO2 and will be spun to about 7000rpm. Is it worth doing on this motor, or should I leave it and wait until the next step up?

Oh, and my top rings are already set at .043 on the forged flat top pistons.

kjett wrote:I'm curious about this as well. I understand the theory of the gas ports is to help with ring sealing at higher rpms, but at what point would it be wise to get your pistons done? I'm building a 466 motor for my all out bog truck, and it will see occasional hits of NO2 and will be spun to about 7000rpm. Is it worth doing on this motor, or should I leave it and wait until the next step up?

Oh, and my top rings are already set at .043 on the forged flat top pistons.

.043 be the thickness not the gap............

[quote="richter69"]

kjett wrote:.043 be the thickness not the gap............

You talking about the distance from the top of the piston to the top of the 1st ring grove? All I know is the rings are 1/16 1/16 3/16 file fit plasma moly rings. And sorry, I don't know why I said .043 as the top gap, they are .024, if I remember right.

Oh, and my pistons are the SRP 150723 .030 forded flat top pistons with the -3cc reliefs cut in them.

[quote="kjett"]

richter69 wrote:

kjett wrote:.043 be the thickness not the gap............

You talking about the distance from the top of the piston to the top of the 1st ring grove? All I know is the rings are 1/16 1/16 3/16 file fit plasma moly rings. And sorry, I don't know why I said .043 as the top gap, they are .024, if I remember right.

Oh, and my pistons are the SRP 150723 .030 forded flat top pistons with the -3cc reliefs cut in them.

.043 - 1/16th - 3/16th

Ah, I see, said the blind man! So the top ring groove would need to be machined for the .043 ring. Now i get it!

So back to the question I had, at what point would it be beneficial to do all this?

To pull a combo apart just to do this alone, not really worth it. Buying a set of pistons anyway............hell yeah.

The reason I ask this is , I bought a set of Ross pistons at the Swap,and they have the Gas ports in them.All except one,which is BRAND new,but it don't have the ports drilled in it. So ,is it worth sending the 1 back to have it drilled, or can a machine shop do it?

Anyone

I'd say, any competent machine shop should be able to do this for you. Just take one of the one's that has the ports already in it for them to measure.

kjett wrote:So back to the question I had, at what point would it be beneficial to do all this?

I'd like to know as well. For this, let's say your buying new pistons and your wanting to know if you should or shouldn't get these ports.

So .... Are these only for race engines? At what RPM do these ports start to show a benifit? Are they a total waist of $$$ for a street only application?

More info please.

gas porting is a series of holes drilled in either the top of the piston or the side just above the top ring land. they allow cylinder pressure to get inside the ring and push the ring out against the cylinder wall as well as down against the ring land. the effect is to improve ring seal.

Gas porting will always make more horsepower. the only negative to gas porting is as you increase loading against the cylinder wall, you will also increase wear on the rings. So, if you are talking about an engine that will be expected to run all season, it may not be necessary. but if you are talking about a piston that has low-tension rings, then absolutely. Remember our earlier question about low-tension rings-they always need gas porting to help improve their seal against the cylinder walls in high-performance applications.

Gas porting does very little under 7000 rpm if anything. A properly honed block, (with plates and fasteners your going to use along with your head gasket). will make more of a difference that gas porting a standard end gap rign. The heavier the ring along with more rpm over 7000 with help stabalize the ring after that rpm. The rpm x ring weight is what causes ring flutter along with other factors not getting into. The smaller the ring package the better the ring will stay on the cylinder wall. You only gas port a heavier ring package along with rpm over 7000.............

just from what i read to realize the gains of "dykes" set ups (gas ported) you'll run the ported pistons, and low tension rings.....and the low tension rings is where most of the gains come from. Bad part is, a vacuum pump usually needs to be installed to pull vapors from the crankcase and aid in 2nd and oil ring sealing.


good luck with your ross pistons

bbf-falcon wrote:The reason I ask this is , I bought a set of Ross pistons at the Swap,and they have the Gas ports in them.All except one,which is BRAND new,but it don't have the ports drilled in it. So ,is it worth sending the 1 back to have it drilled, or can a machine shop do it?

Depends on the top ring....the 1/16" don't require a gas port .

Thanks Lem

bbf-falcon wrote:Thanks Lem

So what is the top ring ?

I would do it on a real street application, better to have good seal rather than a real light pack

Guys,

If and that's a big IF, you are going to gas port for a street engine, then be forewarned that most likely the vertical gas ports will become clogged with carbon. So for some circle track engines that will see a lot of mileage, they use the lateral gas ports. Gas ports and vacuum pumps go together, they are "enablers".

1. Most OEM production engines used a 5/64" X 5/64" X 3/16" ring package. Then the Speed Pro pistons and Hyper stuff that also uses that ring package,,,, in my opinion is not really a performance ring package or piston design.

2. A step above that would be the 1/16" X 1/16" X 3/16" standard tension stuff, which is apporpriate for a street/strip engine.

3. Same ring package as above, but in low tension.

4. The nicer race pistons have an .043" X 1/16" (or .043") X 3/16" ring package, and then we get into the low tension stuff and the backcut rings, Napier second ring and etc. Also the better race pistons have an accumulator groove between the top and second ring to have stablize the top ring at high rpm.

Charlie

Lem Evans wrote:

bbf-falcon wrote:Thanks Lem

So what is the top ring ?

I haven't measured it Lem,I will do that this week. I may never use these pistons unless I find a USED race block. I'm not interested in taking my new A460 block that I'm getting from you and boring it to the max,just to use these pistons. BUT, if anyone knows of one that needs sleeved or whatever, I would do a 598 deal.

Since it hasn't been mentioned, the top ring has to fit the groove very good for the gas ports to work. I don't remember the spec, but I think it's around .001". Sometimes pistons that aren't designed for gas ports will not see any benefit from them because the top ring clearance is too much. I gas ported my own pistons after I verfied that they had a tight enough groove.

Like Charlie said, I would think after time carbon would plug the verticle ports w/a poor tune.