Personally, I wouldn't use 'em.

 

Full circle right? The part number is for a mahle inverted dome. -_-
I even called pre-purchase to make sure I was getting a D dish piston..
Guess that's just how the deep dish pistons are.
Anyone have real life pictures of some other brands of inverted dome forged units? Pictures on the net are hardly accurate.

 

I don't know how much dish you need or even what motor you need 'em for, but here's an example of a KB for a 350 that has a 28cc dish and it's still a D-cup with a generous flat area to create squish.
http://www.summitracing.com/parts/uem-kb121-030/overview/make/chevrolet

 

In recent years, the term "inverted dome" has been used in place of "dish". While it may IMPLY a chamber-shaped dish, it isn't always "so". But hey, it sure sounds a lot cooler than "dish", don't you think? So do piston makers...

Knowing what engine these pistons fit would be a big help in telling you whether or not they're "good" for your application. If you're not "pressing the edge" of compression for the octane used, the "simple" dish is fine. The quench pads come into serious "play" when you're near the limit.

Jim

 

383 with 59cc vortec heads. If im paying over 600$ for pistons, I want exactly what i want. Especially when I call ahead to make sure they have a squish pad. Im returning them.

 

Looks like finding a forged unit with a squish pad in the +26ccish range is about impossible. They all seem to be 2valve relief style. lames.

 

Check Wiseco Pro-tru forged pistons. That's what I have in my 388. I'll post a few pictures in a minute. Also just like cylinder heads the cc's are not exact. I would have to look at my notes, but hen I cc'd the dish it was actually a bit larger than advertised.

 

 

http://www.summitracing.com/parts/wis-pt097h4/media/images/make/chevrolet

 

Dish piston and inverted dome are different ways of saying the same thing. These pistons in your link a what is often called a D dish or D cup. This design combines the advantages of a flat top with a compression ratio controlling dish of some volume. There is a related design called a Step Dish where the wall of the dish is cut away making a step.

These designs compared to the OEM's favored use of an enclosed or circular dish is that the D dish/cup, step, or inverted dome maintains a closely closing surface between the piston and head on the side of the head's squish/quench step. By keeping these surfaces with a clearance of about .040 inch detonation resistance and operating effectivity is greatly improved. The dish or stepped side under the valve pocket is a volume added to the combustion chamber, clearance volume of piston to block deck, and head gasket in order to keep overall compression inside a range the fuel can optimally tolerate.

Bogie

 

Maybe call up SRP and ask specifically about a flat squish pad? Their 148750 looks like a candidate. Maybe a little large. Makes 9.0:1 with a 58cc head.
SMALL BLOCK CHEVY - 350 / 400 INVERTED DOME - JE Pistons

 

Thx guys. I have been looking at the 31cc srp's, just don't know if I really want to drop compression another .5.
I do like the wiseco pistons a lot! I couldn't find those when I was searching. They are right up my alley for sure. I wonder if I can get them for a 5.7" rod?

I also talked to MAHLE. Turns out they sent me the wrong style piston. (they make 2 styles under the same part number, a full circle, and a D dish.)

Hopefully ill have the pistons switched out with not much trouble or time.

 

Nice 388, Camaro man. Those pistons are sweet and are the ones I would have chosen had I found them for a 5.7 rod

 

I don't know how much boost pressure you plan on running, but the trend for turbo engines is to reduce quench. Its part of the reason those type of pistons are making a comeback.

Not saying that one is better than the other, but that is the current trend for high boost engines.

 

So your NOT saying one is better than the other for a mild boost application? Just that seems to be the trend huh.. Its interesting..



The tech guy for MAHLE said close to the same thing. He said its not going to make a bit of difference switching to a D cup from the full circle. Not with my compression anyways. Sais not to worry about quench for a street engine and listed some factory performance vehicles with over .080 piston to deck + head gasket.

I'm trying to build the bottom end to handle 100-150 shot of juice or some boost. As of now the reason for the deep dish is my small chambered heads and wanting to keep compression lower for my TRUCK.

I just figured running 9.4:1 on low grade is like running 10.5:1 on premium. Thought the quench pad would help with resisting detonation but others say the full circle will actually be better because there are no hot spots. Anyways from the start of this build ive had my mind set on some inverted dome D DISH pistons. That's what im going to stick with.
Later when I boost it I can go to a thicker head gasket if I need to reduce quench I s'pose.
For now im shooting for .036-.038 head gasket with 0" deck height.

 

I like your plan, stick to it.

Yes, they make those Wiseco pistons for 5.7" rods too. J&E also makes some as well, I have them in my other engine.

 

Supposed to be getting a call from MAHLE after they check the shelf stock. If they tell me that im going to have to wait for some to be made im getting those wisecos

Thanks for liking my plan lol I haven't got a lot of positive feedback about the build :embarrass. I think its going to be a fun low-mid rpm motor.

 

Well the tech for CNC motorsports is SERIOUSLY trying to talk me out of the D shaped dish. Said the only reason the D shaped dish is common right now is for COST reasons, it is cheaper to make the D shape.
Sais the quench pad will make absolutely ZERO difference for flame travel or chamber mirror. Actually he said the full circle dish is the best for flame travel and efficiency AND detonation resistance. The MAHLES that I want are NOT available apparently.
Also the wisecos are 650$, the MAHLES are 750$. He said its going to cost me MORE to get the wisecos over the mahles because they are not a dealer for wiseco.
Then he told me that he could issue a 400$ credit for the return of the mahles. FOUR HUNDED DOLLARS! Lets do the math, My total bill for crank, rods, pistons, bearings, rings, and shipping was 1,783$ that makes 1,383 with the 400$ credit for pistons.
Minus 650$ for crank makes 733$, minus 418$ for rods makes 315$

315$ for some bearings? I relize they need to make some money but seems like this is starting to look like a bad deal. Really? you send me the wrong pistons and I have to pay for return shipping?

Also I gave him the part number for the wisecos and he said he couldn't get them. He told me that they are putting out over 25 engines a month and I shouldn't have any worry about the full circle dish. Thing is, that's what I want, and what I called ahead to ask for, specifically.
Thanks for letting me rant as I just got off the phone with CnC, Now I get to figure out what to do next :smash:

 

If David Vizard or one of the engine builders on this forum told me what this kid is tellin' you, then I would believe what they said. But a kid on the phone is the same to me as a kid at Autozone or Summit or any other parts supplier. What the hell do they know? They're just tryin' to stuff parts down your throat and make a profit.

 

return it all and eat the cost of shipping. Sucks that you have to pay for shipping but it'd probably your best route out of this mess.

 

Called Wiseco and they actually do not make Camaro Mans pistons for a 5.7 rod. I don't want to have to pay shipping when THEY sent me the wrong piston. Shizzt happens though. Still haven't found a piston to buy.

 

why the overkill for a low rpm engine anyway? Did I read that you're going NA? Seems like a lot of money for something you really don't need.

Not that it hurts anything but its just WAY overkill.

 

I am going to hit with some nitrous.
This has been a pretty big mess I think im going to return it all and buy this 468 bigblock for 3000$

 

Now, THAT sounds like a solution! Shame you've been worked over like this.

Pat

 

Okay, MAHLE is swapping out the pistons for some 6" rod pistons with the D shape and no rail. They are very nice about the situation and paying for shipping both ways.
I have to swap my 5.7 rods with CnC motorsports, and I have to pay for shipping both ways. Would have been nice of them to pay atleast one way, Since I did not get the product they assured me I was getting. No biggie I s'pose, as long as its getting resolved.
I will defiantly think twice before ordering from CnC again. Customer service is very rude, they don't care about correcting their mistake unless its no cost to them. Also, I did the math, Really didn't save hardly any money at all going with the full kit through them. Sure didn't save any money now that im having to pay shipping costs to correct their mistake.

 

This is why I hate buying through intermediaries. A whole lot of fingerpointing and in the end you're the one thats gonna get reamed. Sucks.

And Im still the 'kid' at the parts business; so I see both sides, Im lucky that my boss tends to under-promise and over-deliver, especially if customers with returns are nice about it.

Is CNC that WISSOTA-based roundy-round company thats in MT or SD?

If you dont live within a couple hundred miles of them; Im sure theres a local guy who would be more than happy to have your business.

Hell if you insist on buying parts from a guy you don't know; theres always Mike Lewis in CA. Hes a super nice guy, a straight shooter and a wizard at oddball combos.
I can't say Id build the motor the same way you are; but theres nothing that would scare me off. Just different strokes for different folks.
Stay upbeat, positive and polite; eat the shipping if you have to and take it as a learning experience. Keep us posted.

 

Parts direct to the end user is often not a option due to distributor contacts and often at a much higher costs to the end user.
Some manufactures screen end sales for a dealer with a point system in customer satisfaction.If there is enough negative feedback pull their line out of the dealership.
Wiseco happens to be one of the brand names that sells it's self not needing any dealerships.

CNC motorsports is a member on this forum.From the posts I have read,their posts have been correct.I am guessing the source of that info is coming from the owner of the business.I am also guessing you have yet to talk to him directly on the phone.If you where a customer of ours,I too would refuse to deal with this private matter on a open forum out of common respect for each other.

I suggest your might be one phone call away to talk directly to the owner from finding a better solution to your issue.

 

Parts direct to the end user is often not a option due to distributor contacts and often at a much higher costs to the end user.
Some manufactures screen end sales for a dealer with a point system in customer satisfaction.If there is enough negative feedback pull their line out of the dealership.

That is what I was saying here: http://www.hotrodders.com/forum/skipwhites-383-rotating-assembly-228238.html#post1633859. Then you seemed to have been saying the opposite of what you're saying here.

I had said:

Many if not all manufacturers do not offer price breaks to individual buyers. They instead offer the price breaks to vendors who buy in quantity.

Your reply was (bold mine):

We have networked manufacture direct purchases for yrs.Well really we have met many face on face and created those contacts.We aren't anyone special,so if your willing to do some leg work,you would be amazed at what you can get done.

 

We have bought those quantities I guess.The relationships I think we have created along with a clean customer record has played a huge role.

Anyone who has CNC machines involved in their business has hundred of thousands invested and the small money we talking here isn't significant.Don't get me wrong,the high performance end doesn't have a big margin so those businesses are not a cash cow.Many machine shops earn their bread and butter in production runs of industrial parts and the high performance end of the deal is just some cream on top of that.Again not the main source of income.10,000 wiggets is worth a ton more than a bore on a block.

When I said we aren't anything special I meant if we have been able to do what we have,anyone follow the same formulas could as well.

 

thanks guys. will post pics when the new pistons arrive. +26cc for 6" rods. Should be interesting.

 

Pistons arrived today, stoked. The guys at MAHLE are great to work with.