Pistons with Lateral Gas Ports?
11-22-2005, 08:20 PM
#1
Staging Lane
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Pistons with Lateral Gas Ports? Talking with an engine builder here in Houston. His suggestion is to Wiseco Custom Forged Pistons with lateral gas ports. The ports stabilize the rings at high rpm and are low friction. What do the gas ports do? How much more power? I am trying to see if the added cost is worth it. He stating that this piston and ring set up is worth 30 hp. He is using NPR stainless / chomoly rings. This for an LS2 402 solid roller stroker so it will be seeing high rpms.
11-22-2005, 09:15 PM
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Read about this a while ago.
The pressure in the cylinder is used to press out against the compression rings
for a tighter seal.
It will also help stabilize the ring (reduce flutter).
I don't know what to say about the horsepower increase, but I know this sort
of porting is used in high end drag racing engines ( I believe the ports are drilled
vertical for more pressure).
What's the cost associated with the porting compared to non ported pistons?
The pressure in the cylinder is used to press out against the compression rings
for a tighter seal.
It will also help stabilize the ring (reduce flutter).
I don't know what to say about the horsepower increase, but I know this sort
of porting is used in high end drag racing engines ( I believe the ports are drilled
vertical for more pressure).
What's the cost associated with the porting compared to non ported pistons?
11-22-2005, 10:58 PM
#3
Staging Lane
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I have not spoken with them about specific part costs. They quoted me a short block price of $5700. They are using some expensive pieces for the rods, crank and billet main caps.
11-23-2005, 07:29 PM
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The deal with gas ports is they allow tighter ring land clearance since pressurization is accomplished with the ports. This tighter clearance is how flutter is controlled, this can be worth 20 to 30hp since it allows higher rpm with out ring seal loss.This also adds power by taking less piston movement to start building pressure,similar to moving top ring up on piston.Lateral gas ports are more street friendly since they wont carbon up as quickly as vertical ports.
11-23-2005, 07:36 PM
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Does anyone have a cross section of the vertical and lateral ports?
I'd like to see how this works, and how the carbon is less likely to build with a
vertical port.
Thanks.
EDIT: Been doing some quick searches and found this
http://www.highperformancepontiac.co...08pon_pistons/
* Gas porting: consists of drilling small holes through the tops of the pistons, which allow cylinder pressure access to the back of the top ring to force it out making it seal more tightly to the cylinder wall. They are most effective with tight ring grooves and high ring positioning. Moe doesn't recommend vertical gas porting (holes drilled through the top of pistons) for street applications. First, the engine probably doesn't develop enough cylinder pressure to unseat the rings and second vertical ports plug up with carbon in a street engine after a short time. As a result vertical gas ports are most often use for drag engines and horizontal ports (drilled through the side of the pistons) are used on circle track and road race engines (and on street engines...sometimes). Unless you have 600 hp or more, Moe says not to worry about gas porting.
I'd like to see how this works, and how the carbon is less likely to build with a
vertical port.
Thanks.
EDIT: Been doing some quick searches and found this
http://www.highperformancepontiac.co...08pon_pistons/
* Gas porting: consists of drilling small holes through the tops of the pistons, which allow cylinder pressure access to the back of the top ring to force it out making it seal more tightly to the cylinder wall. They are most effective with tight ring grooves and high ring positioning. Moe doesn't recommend vertical gas porting (holes drilled through the top of pistons) for street applications. First, the engine probably doesn't develop enough cylinder pressure to unseat the rings and second vertical ports plug up with carbon in a street engine after a short time. As a result vertical gas ports are most often use for drag engines and horizontal ports (drilled through the side of the pistons) are used on circle track and road race engines (and on street engines...sometimes). Unless you have 600 hp or more, Moe says not to worry about gas porting.
Last edited by Adrenaline_Z; 11-23-2005 at 07:43 PM.
11-23-2005, 07:49 PM
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ALright last post. I found a good PDF on what vertical and horizontal porting
is.
A vertcial port is drilled from the top of the piston and vents to the top compression
ring groove.
The pressure above the piston on the upward strokes pushes the top compression
ring out against the cylinder wall.
A lateral port is drilled from the side of the piston, just above the top compression
ring and vents behind the ring.
Now I understand why the tighter clearances are needed as well.
is.
A vertcial port is drilled from the top of the piston and vents to the top compression
ring groove.
The pressure above the piston on the upward strokes pushes the top compression
ring out against the cylinder wall.
A lateral port is drilled from the side of the piston, just above the top compression
ring and vents behind the ring.
Now I understand why the tighter clearances are needed as well.
11-24-2005, 06:36 AM
#7
I just was working on a set of gas ported LT1 pistons. Top ring to land clearance was .0008.
The ring width needs to be small like a .043 ring or a 1.2mm otherwise the pressure has to overcome a stffer ring radially. I suggest not using an off the shelf ring. The ring has to be as flat as possible for it to seal right and work freely in the groove. I just paid a little over $500 to get the best rings possible.
The pistons have to be cut with very flat ring grooves too or the package will not yield you the results you are looking for.
Gas ports have been know to wear rings faster due to the higher forces against the wall.
The advantages are the tigher ring seal and the lower ring drag during the rotational events that do not produce high pressures in the cylinder.
My 2 cents.
Rich
The ring width needs to be small like a .043 ring or a 1.2mm otherwise the pressure has to overcome a stffer ring radially. I suggest not using an off the shelf ring. The ring has to be as flat as possible for it to seal right and work freely in the groove. I just paid a little over $500 to get the best rings possible.
The pistons have to be cut with very flat ring grooves too or the package will not yield you the results you are looking for.
Gas ports have been know to wear rings faster due to the higher forces against the wall.
The advantages are the tigher ring seal and the lower ring drag during the rotational events that do not produce high pressures in the cylinder.
My 2 cents.
Rich
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11-24-2005, 10:29 AM
#8
Staging Lane
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So if my car will see more street than track duty (drag or road) then I would probably shouldn't do this. I am not interested in having to freshen the motor on a regular basis. Plus the LSX's are prone to carbon build up because of the crappy pcv system. This would adversely affect the rings sealing if the ports carbon up.
11-24-2005, 11:58 AM
#9
It is not something I would do for a daily driver motor. If you decide to do it anyway, do the lateral ports. If for some reason you do the top ports have the piston tops coated. It may keep them form clogging longer.
I learned a long time ago two things.(I'm old now) Give up some of the trick stuff for reliability and be realistic with your combination for what it will be used for.
Also,don't belive all that crap they put in the magazines either. I have been in almost everyone of them and I sure as hell did not give up all the goods on my combinations and sometimes did not even tell the truth. Magazines are there to sell ads.
Rich
I learned a long time ago two things.(I'm old now) Give up some of the trick stuff for reliability and be realistic with your combination for what it will be used for.
Also,don't belive all that crap they put in the magazines either. I have been in almost everyone of them and I sure as hell did not give up all the goods on my combinations and sometimes did not even tell the truth. Magazines are there to sell ads.
Rich
11-25-2005, 09:35 AM
#10
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Stock is right--lateral ports are the way to go--as far as the extra expense goes--some companies have ports as std design and you can get them off the shelf.I know that most Bikes come stock with holes under the rings and I bet alot of cars do too.
11-25-2005, 03:37 PM
#11
Those holes better be above the rings. The ring seals against the bottom of the ring land and the flatter and smoother you make that the better off you will be.
Sometimes there are accumulator grooves between the top and second ring. These are there to give a slightly larger space for pressure that builds up between the rings which is bad because it tends to try to lift the ring and upset the ring sealing to the bottom of the groove. Engine builders are opening up the second ring gap to make sure this pressure passes.
Sometimes there are accumulator grooves between the top and second ring. These are there to give a slightly larger space for pressure that builds up between the rings which is bad because it tends to try to lift the ring and upset the ring sealing to the bottom of the groove. Engine builders are opening up the second ring gap to make sure this pressure passes.
11-28-2005, 07:26 AM
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I would imagine a lateral gas port is more effective if the ports are located above
the first compression ring?
If the gas has already passed the ring, the pressure would reduce at the skirt,
correct?
the first compression ring?
If the gas has already passed the ring, the pressure would reduce at the skirt,
correct?
11-30-2005, 02:01 AM
#14
FormerVendor
Gas ported pistons are a system and usually use back cut rings and tighter lands and then the rings must be better and flatter or they can stick. Gas porting regular shelf pistons not meant for gas ports might possibly make them seal a little more and flutter a wee bit less but they will also wear faster now as well since they aren't designed to be used that way by the original ring engineers. If you are not sure ask the ring guys like Barry R. from Speed Pro or others.
If you want real gas ported pistons you need to order them that way with all the right parts so the whole deal works like a system and seals better, flutters less at high rpm and has lower frictional ring drag. Having the right rings is most of the gain just like a good dry sump. It's not the dry sump it's the rings used with the dry sump!
If you want real gas ported pistons you need to order them that way with all the right parts so the whole deal works like a system and seals better, flutters less at high rpm and has lower frictional ring drag. Having the right rings is most of the gain just like a good dry sump. It's not the dry sump it's the rings used with the dry sump!
12-12-2005, 03:47 PM
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I would not recommend gas porting on anything but a full out race engine. They will eventually fill up with carbon, which will be a potential source for pre-ignition. Also, you most definitely do not want one or two to plug up and apply unequal force circumferentially around the piston.
Gas porting is needed in race engines, but it’s done because of the type of rings used and the absolute need for total ring seal at high rpm. Titanium and Chrome nitrite top rings are typically the type used, and in a 1.2 mm size. Both of which last very well, but are difficult to seal. Gas porting gets them to seal. Molly seals very well, but will not last in a race engine for very long. Also, machining the gas ports is a trick best left to the manufacture. JE happens to be my favorite and I’ve never had an issue with them, ever. Wiesco is a back up. Leave it up to them to determine placement, size and number of ports for the ring type, ring size and how long the race is. I’d also recommend that if you do go this route, coat the bottom of the top ring land, or the bottom of the ring itself with a dry film molly lubricant to keep the ring from welding in the grove. Make sure you use a good Indian stone to de-bur the groves too. Just hit the edge lightly. You’ll also want to take an exacto knife to the ports to make sure that there are no bur’s that will promote carbon build up, or hot spots.
Make sure you do all this port and land prep before you mock up the assembly. Bur’s throw off your measurements. And don’t forget to polish the **** out the pistons with a light scotch bright buffing wheel.
Gas porting is needed in race engines, but it’s done because of the type of rings used and the absolute need for total ring seal at high rpm. Titanium and Chrome nitrite top rings are typically the type used, and in a 1.2 mm size. Both of which last very well, but are difficult to seal. Gas porting gets them to seal. Molly seals very well, but will not last in a race engine for very long. Also, machining the gas ports is a trick best left to the manufacture. JE happens to be my favorite and I’ve never had an issue with them, ever. Wiesco is a back up. Leave it up to them to determine placement, size and number of ports for the ring type, ring size and how long the race is. I’d also recommend that if you do go this route, coat the bottom of the top ring land, or the bottom of the ring itself with a dry film molly lubricant to keep the ring from welding in the grove. Make sure you use a good Indian stone to de-bur the groves too. Just hit the edge lightly. You’ll also want to take an exacto knife to the ports to make sure that there are no bur’s that will promote carbon build up, or hot spots.
Make sure you do all this port and land prep before you mock up the assembly. Bur’s throw off your measurements. And don’t forget to polish the **** out the pistons with a light scotch bright buffing wheel.
12-15-2005, 12:22 AM
#17
From Car Craft:
The ultimate in ring seal is drilling the pistons for gas ports. Compression rings normally need about 0.002-0.004-inch (vertical) ring-to-groove side clearance to allow cylinder pressure to get behind the ring and force it to seal against the groove and cylinder wall. Gas ports apply combustion pressure directly to the back of the ring, allowing the virtual elimination of side clearance. Since the ring is restrained by the groove itself, there’s less opportunity for high-rpm ring flutter. Very thin, narrow, and lightweight 0.043-inch–thick rings are needed to reap gas-porting’s full benefits. Gas ports work best with short piston-compression heights (under 1.200 inches) on engines running 7,000 rpm or higher. The major drawback is that all this positive pressure greatly shortens ring life, so it’s not recommended for street use.
