The best piston is more than just a brand name as it's more about who designed it and what you need out of it. All the good piston companies CAN do a good piston but that doesn't mean you will get one. I use Wiseco and Diamond but I only go through certain people and I have been ordering and actually building engines with the same pistons for a long time.

You also need to have nice straight and round bores with the right finish on them for the rings you will be using. This is not something the normal guy can even inspect so you need to use a real machine shop that does real engines and has the appropriate tq. plates and the right hone and stones or diamonds etc.

You need to know everything about the engine including the real duty you will be subjecting the pistons to. Piston speed is a non issue but the important things are fairly complicated so you need to know a lot more than the average piston tech will ask you since they usually don't really give a damn. Been there done that 1 million times.

I've been fixing crap thrown out by big piston companies for years. You can get a great piston from company XYZ if you go through one guy there and yet a POS from another guy there just by how they put your order in so be wary and only order a custom piston from someone that knows WTF they are doing.

Shelf pistons I think Wiseco and Diamond have the biggest selection and understand the LS1 best at this point. In addition shelf Wiseco's have skirt coatings and anti detonation grooves on the top land and a pressure accumulator groove on the second ring land and feature double pin oilers and an inboard pin boss design as standard which clears the block and reluctor very well on 99 percent of builds.

I order custom pistons for several shops and of course on all our own builds and have decided to start doing more customs if people want to go through us for Wiseco or Diamond. I can only be reached by email 99 percent of the time and then I can call customers back but we are too busy to answer the 4 phone lines we have on a regular basis unfortunately plus calling is BS untill you know what you really want.

I have my own piston build sheet form and having done about 1000 sets of custom pistons that we used oursleves aver the last decade I have a small idea of what works. Keep in mind though that pistons ARE compromises sometimes so you have to realize you can't just do anything with any piston.

 

Gold ^^^^^^^^ !

 

Can you explain how the anti detonation grooves on the top land and the pressure accumulator groove on the second ring land work, and describe what they look like? Expecially the Anti Detonation Grooves.

Thanks.

 

When the top of the piston swells from detonation these grooves touch first among other things and help cool the top and reduce friction there. also as quoted from many other sources : "The Anti-detonation grooves prevent carbon-buildup from locking up the top ring. They also help keep the air and fuel in suspension. These grooves knock the peaks off shock waves within the cylinder, reducing the propensity to detonate. They also temper pressure spikes and enhance piston ring life. The presence of this feature depends on your piston manufacturer as some have them, some don’t."

The accumulator groove on the second land increases the volume under the top ring and above the 2nd ring so the top ring doesn't unseat as much. The top ring is held down and out by gas pressure differential and of the space under the top ring fills up and equalizes then the top ring doesn't seal very well. You also want a larger 2nd ring gap for this reason. Another quote from various sources : "The accumulation of gases that get by the top ring can unseat it. A pressure groove delays this action. This is why today's recommendation is to keep the 2nd ring end-gap as large as or larger than the top ring end-gap. It is a shaped channel that works by equalizing the pressure seen between the top and second ring with the pressure in the combustion chamber. This feature enhances ring seal, improving power, and engine life and fuel economy. The presence of this feature depends on your piston manufacturer as some have them, some don’t."

 

The thin grooves above the top ring are the anti-detonation grooves and the single large groove is the accumulator groove in the second ring land.

Also the Diamond and the Wisecos are usually supplied as pass and driver sides with offset to keep them quite in street engines when they are cold.

 

I will check the pictures of my pistons I took tomorrow and see if they have the grooves. As best I can remember they do, but I do know they are not offset. I do not remember why but we chose to go with them zeroed, no offset. There was a reason for this I just can not recall at this time. You might know the pros and cons to this. I can testify they ARE loud. They are louder at startup and they get quieter after they get heated up. Not a knock kind of loud, just an annoying sowing machine kind of tick that is noticeable and it would concern and annoy someone that did not know what it was. I would advise most people would not like the noise.

Also aren’t there two different forged aluminum alloys, one being stronger and softer but wears faster then the other?

 

I will try and post the pics of my Ross pistons tomorrow.

 

one is 2618 aluminum alloy and the other on is 4030 ?

i have wiesco 2618

 

So you like .07" cylinder wall thickness? OK, that will last a while!

 

Most race only deals have no offset but vitually all street cars in the world even with tight cast pistons have offset for piston noise reduction. I don't think it makes a lot of difference or any at all in power but some piston designs or forgings themselves are not condusive to offset so maybe that was why?

 

Mine is the softer of the two, which ever that is.

That might have been the reason behind my offset being zero, again they can be heard until it is all up to operating temp. I think the extra clearence due to the alloy mixed with the short skert design contribut the this as well. I almost went with a custom set of Wiesco pistons, but all I knew of them was in dirt bike pistons (this area the are king in).

 

Yes most of your aftermarket performance stuff is 2618 alloy for it's toughness and for insurance. The other common alloy 4032 is harder but more brittle and most pistons companies only use it for NA only apps because of that.

 

good thread. I was considering a set of Mahle's for my build. they come with a coating and have the "inboard pin". Ant thoughts on these?I ordered a set for my honda and they were quite nice to look at.

 

I like the Mahles except for abuse as they used to all be 4032 but I don't know if maybe some of the new stuff is 2618? They would self-destruct in the Texas NOS deals that everyone runs down here but in NA use they seemed good.

 

I recall Jenkins or Yunick or someone similar commenting somewhere about 25 years ago that the offset did cost a few HP. Like 2 or 3 in an SBC. The cost of quiet in a production car. I just love the sound of piston slap in the morning, so always had zero offset pins. Quiet as a mouse when hot.

Do you find the offset Wisecos and Diamonds are dead quiet on cold start with abuse type P to B clearances?

 

Venolia FTW

 

That's a good question as I have been able to drive and hear a lot of stuff we do and 90 percent has offset in it. You can definitely hear the no offset deals and yes some people have been freaked out but I told them that when they brought us their non offset stuff.

Interestingly enough we have never even had a qyestion about piston slap or noise on the Wiseco and Diamond stuff with offset ever so far in 7 years so it has got to be a substantial difference seeing that we have done over 1000 of these engines and it blows my mind that I have never heard a single complaint.

I would still expect at least a little noise though especially with the bigger clearance stuff even with offset though to answer your last question like when we specifically put in more cold clearance for a bigger power adder deal etc. There has to be more noise I would think but I guess not enough to freak people out a lot at least so far?

On the stroght pin no offset deals with really big clearances people actually do worry and think they have a diesel untill the engine is pretty hot. I think it depends on your exhaust and what other noises you have to distract yourself probably. My old mustang with no offset Manleys and some bigger clearance was pretty loud until the engine was hot.

People even would tell me at races to turn it off and check the oil since my engine was knocking! Hahahahaha.

 

I feel like doing the same some times. I just got accsess to my pics of my pistons and they do not have the grooves on the sides like I thought they did,but you can see how thick they are. I remember I was stunned at this because the builder had a set of Diamond and JE pistons there that were about half as thick. My builder for some reason told me he would not build any more LS engines with Diamond or JE pistons. He had a set with the tops pulled of and another set with two cracked. Both of these engines were not built by him but was brought to him for repair. They were both low milage FI engines that were bought from a sponsor (I will not name who). That said I personaly believe, because I know the people that owned the engines, the problem was not the builder or the pistons, but instead the owners abuse and power adders. They bought engines for one aplication (NA) and tried to utilize them in another (FI). But unfortunatly the builder is now scared off these two piston brands. Here are my pics, please look at them and tell me what you think of them.

 

Here are two more pics with the pistons out of the bore. You can see on the bench my pistons, they are the first two rows and the others were going in either a 540 BB chevy marine race engine or a 500+ ci BB Ford race engine, I do not remember which nor do I know what brand they are.

 

Your pistons don't have the webbing underneath like mine do for some reason. I thought that was standard for Ross ls pistons?