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 Post subject: Re: Gas Porting Pistons?
 Post Posted: Wed Feb 09, 2011 7:56 pm 
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rick360 wrote:
want-a-be wrote:
I've seen a tenth in a few combinations that had 1/16th" rings. The only thing changed in the car, bumper to bumper, was me freshening the engine and adding gas ports to the combination.

Don


Were you the original builder also? Yes

Were the rings standard radial thickness? or back-cut to reduce radial thickness/tension? No to before and after

In a drag car? Yes

What engine combo? Stock blocked .040 over 350 chevy block not filled, Lunati pro series crank 3 ¾ stroke, eagle rods, wiseco pistons, old set of cnc ported track 1 heads, solid roller cam-motion cam nothing huge though, Super vic intake, ported by me, Ken Jones alky carb. Nothing special. I prepped everything around this rotating combination and built assembled it about 13 years ago, when I had the Speed Shop I've mentioned before. I've been the only person to freshen this thing up.

ci, 385 chevy

rpm 7500

, compresison, 13.8-1

vac pump etc? Never has ran one, but wanted him to.


A tenth is a fair amount to gain ... in a normal 600hp 2600# car that would be 20-25hp. The tenth was on an 1/8th mile track, Car is a hard tail Nelson dragster. The tires on this thing was even the same as the year before.


Take it for what it's worth, doesn't really matter to me one way or the other. Remember this though,...when gas porting was first conceived of there were no special rings, 1/6th rings were cutting edge, (if they even had them at the time), and there was no vacuum pumps. But gas ports were noted for increasing hp with out all the supporting stuff we have today. Just a thought. ;-)


Thanks,
Rick

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 Post subject: Re: Gas Porting Pistons?
 Post Posted: Thu Feb 10, 2011 1:04 pm 
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Thanks for the answers and info. Thats a pretty good gain and I appreciate you sharing your experience.

want-a-be wrote:
Remember this though,...when gas porting was first conceived of there were no special rings, 1/6th rings were cutting edge, (if they even had them at the time), and there was no vacuum pumps. But gas ports were noted for increasing hp with out all the supporting stuff we have today. Just a thought.

That is a good point and I think the plan for the rings on the 383 I'm working on will be to get good ductile iron file fit top ring with as low tension of oil ring as I can get and maybe a Napier 2nd ring. I'll gas port the pistons (thinking lateral but not sure yet) and rehone the block.

Rick


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 Post subject: Re: Gas Porting Pistons?
 Post Posted: Thu Feb 10, 2011 6:28 pm 
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Rick,

2 years ago I freshened up a 383 I built for a circle track guy in the street stock class. I gas ported his pistons and he noted a definite power gain and a decrease in lap times.

I'd have to look up his build sheet to find the part number,....but I put in a set of 1/16th rings from Total Seal that were, imo, a very good set of light tension rings. I installed all the pistons and I swear the friction on that set of rings had the less drag on them that I had ever seen on a 1/16th ring pack. This year I have the same engine apart and tried to get that set of rings again. Haven't been able to find them any where. If you are interested I can look up the Total Seal part number and post it here. It is pretty close to what I installed this year but had a dash number on it denoting light tension. I would gas port the pistons if it were mine guys.

There are a lot of old tricks racers use to do back in the day that some try to put down. But you have to remember, back then, if the big 3 (Chevy,Ford,and Chrysler) didn't make it you didn't race it. You have to take stock production parts and massage then into submission to work at the rpm then wanted to be at. Wayne County was taking stock steel 283 cranks and down stroking them when the were running the old modified eliminator class in the 70s. They were leaving the line at about 10.5krpm and shifting about 12krpm. Not sure of the rods they were running. But stock rods modified buy them wouldn't have surprised me.

On a side note Rick, I didn't answer you on speed talk because I did here. Thought I'd give Ken the exclusive to the story in light of his comments ...lol =D> Here ya go ken,.... [-o< lol

Don

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 Post subject: Re: Gas Porting Pistons?
 Post Posted: Thu Feb 10, 2011 6:46 pm 
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want-a-be wrote:
On a side note Rick, I didn't answer you on speed talk because I did here. Thought I'd give Ken the exclusive to the story in light of his comments ...lol =D> Here ya go ken,.... [-o< lol

Don


So exactly what is it you're trying to say Don? =; Don't hold back! ;-)

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 Post subject: Re: Gas Porting Pistons?
 Post Posted: Fri Feb 11, 2011 10:17 pm 
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LOL Ken, just messin wit ya.

Rick,

I looked up the Total Seal ring number that we used on the last build of that 383 I was talking about. The ring set PN# was CRL3690-35. I really liked that set of rings I thought they did a very good job,...especially for the price. This year we tried to find the same PN# and couldn't find them. But I will admit, I didn't do any calling. All we could find was the CR3690-35 rings, or that's what the car owner bought me to install that is.

Let me know what you find out as I'd love to know why they stopped making them.

Don

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 Post subject: Re: Gas Porting Pistons?
 Post Posted: Sat Feb 12, 2011 10:33 am 
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want-a-be wrote:
I looked up the Total Seal ring number that we used on the last build of that 383 I was talking about. The ring set PN# was CRL3690-35. I really liked that set of rings I thought they did a very good job,...especially for the price. This year we tried to find the same PN# and couldn't find them. But I will admit, I didn't do any calling. All we could find was the CR3690-35 rings, or that's what the car owner bought me to install that is.

Let me know what you find out as I'd love to know why they stopped making them.

Don


Here is that ring set at Summit. It has a 16# oil ring, what they refer to as "Low Tension"
http://www.summitracing.com/parts/TSR-CRL3690-35/

I will probably be getting the CRG3690-35 (11# oil ring) only with a Napier 2nd ring for this 383 I'm working on. Decided against zero gap based on comments from various sources. I will gas port the pistons, probably lateral gas ports for this application.

Rick


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 Post subject: Re: Gas Porting Pistons?
 Post Posted: Mon Feb 14, 2011 11:12 pm 
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I talked to SRP today about pistons for an engine build, and the topic of gas ports came up.
He said he has never seen a power loss with gas ports unless the wrong rings were used, like wrong radial size vs the ring groove. I asked about 1/16" rings and he said it would gain some power, but not what a thinner ring set would gain from gas porting. He said vertical were a little better, but if lateral were all that's legal, he'd run lateral gas ports.

He did seem to think there was more power with a change from 1/16" rings to .047" or .043" rings, than from gas porting.

Just thought I'd post what I was told.

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 Post subject: Re: Gas Porting Pistons?
 Post Posted: Tue Feb 15, 2011 8:40 am 
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Ended up ordering the Perfect Circle (Now Clevite/Mahle) 315-0005-35 from Star for $112. Supposed to be 10# oil ring tension (lower than the Total Seal Ultra Low tension by 1#) , a lower tension top ring and a Napier 2nd ring. Should come in today or tomorrow as they are right down the road in KC. Will let you know how they look.
http://www.starperf.com/index.php?p=product&id=416282&parent=0

Rick


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 Post subject: Re: Gas Porting Pistons?
 Post Posted: Tue Feb 15, 2011 9:40 pm 
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Sounds like a good ring pack Rick, thanks for sharing it with us.

I have to agree with the conversation you had with SRP. You'll gain more with the correct ring pack, and the .043 ring with the gas ports will make more power.

Don

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 Post subject: Re: Gas Porting Pistons?
 Post Posted: Mon Feb 28, 2011 9:44 pm 
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I'm going do the gas porting on mine in the next couple days. I run a single .043 compression ring on a 4.030 piston. I can easily get either 9 or 10 lateral ports spaced either 1.40" or 1.26" apart. What would be best? If I understand this right the ports will be half the drill diameter cut in the top ring land just to the depth of the ring groove. For a .043 ring do I use a .040 drill? When installing the rings do you try to space the end gap 1/2 way between 2 of the ports?

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 Post subject: Re: Gas Porting Pistons?
 Post Posted: Mon Feb 28, 2011 10:38 pm 
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Gearhead,

If you want to give me a call pm me and I'll be glad to talk you through it. Do you have the tool from Goodson, or some other method of making the gas ports? Either way I would be more the happy to answer any questions on the phone or here you may have.

I can easily get either 9 or 10 lateral ports spaced either 1.40" or 1.26" apart.


When I gas port pistons I try to use a spacing of 1.375". But I Have changed that up a bit on the last few sets of pistons I've done. I'll mark the piston on both sides near the valve reliefs where I think they would leave the most meat, usually right near where it first breaks over. But you need to make sure that the next gas ports going towards the deeper end of the reliefs are past the deepest part of the reliefs. It is easier then I can explain it in text for as I am not not an eloquent assembler of words. [-( From there I measure both directions from the first 2 marked gas ports and divide it up as close to 1.375 as I can. You may need to mark the first piston up a few times before you are satisfied. But once you settle on a good pattern you need to mark the rest of the set the same way. I use a 12" part of a 1/2" tape measure I cut up. It wraps around the piston pretty good. Cut use I cloth sewing tape if you prefer.

If I understand this right the ports will be half the drill diameter cut in the top ring land just to the depth of the ring groove.

Yes. You want the gas ports to go to the back of the ring lands. If you have the tool from Goodson it is a pretty easy setup. If not, let me know how you are going to gas port your pistons and I'll give an opinion. That's the best I can do.

For a .043 ring do I use a .040 drill?

The tool sold through Goodson has a .043" hole in it. So if you're going with it then yes. You may be able to ask them for a larger hole if you prefer. I wouldn't shy away from a .062" gas port in that ring land though. Something else we could talk about though I guess.

When installing the rings do you try to space the end gap 1/2 way between 2 of the ports?


Nah,...the rings are rotating every time the go up and down in the bore. That's part of the reason for the proper cross hatch angle.

Don't know if this helped out any, but I hope so. Let me know. Keep us informed. ;-)

Don

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 Post subject: Re: Gas Porting Pistons?
 Post Posted: Mon Feb 28, 2011 11:27 pm 
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Don, the local machine shop has some sort of fixture to do this with that he offered to loan to me. I haven't had the chance to check it out yet but he said it will do both vertical and lateral ports and works best in a drill press. I have a junk piston I was going to practice on. If the tool he has is too much trouble to use I'll probably order one from Goodson.

The heads on my motor are Ford Cleveland style with canted valves. The intake valve relief is close to the ring land in one spot and the rest of the ring land has plenty of meat. So there is only around 1/2" of ring land that I can't put a gas port in so there really isn't much limiting the number of ports or spacing on these pistons. I used the 1.26 or 1.40 because you had posted that you like 1.375 and I just didn't know which would be better.

I wouldn't mind discussing this with you on the phone. If you PM me your phone number and the best time to call I'll just give you a call. Thanks.

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 Post subject: Re: Gas Porting Pistons?
 Post Posted: Tue Mar 01, 2011 6:20 am 
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Ford??? I can't be talking to you.... [-o< lol... I may taint the reputation that I don't have :-

Sending a PM right after I post this.

I will usually space the gas ports around the valve reliefs a bit farther a part. They don't have to be symmetrical.

Don

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 Post subject: Re: Gas Porting Pistons?
 Post Posted: Tue Mar 01, 2011 10:15 pm 
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Chuck,

It was very nice talking to you on the phone tonight. I'm looking forward to hear how your changes affect your combination.

I've posted some pix on another site about piston dome preparation and a tool that I use to hold it. If I can figure out how to post them here I'll post some before and after pictures on some of what I do. I think Ken had to help me out the last time. I think they are about 30kb Ken. Let me know if you want them on here or not. It's a cheap tool that's easy to make with scrap around the garage.

Don

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 Post subject: Re: Gas Porting Pistons?
 Post Posted: Wed Mar 02, 2011 2:23 pm 
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It was good talking to you Don. I appreciate all the help. I will try to post pics of the gas porting once I get to it. I went by the machine shop today and the fixture they have for gas porting looks like it would work fine for vertical ports but not so well for the lateral ones.

I had a couple of questions for you before I order the tool from Goodson if you would check your PMs. Thanks

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