AA Pistons Are Causing NightMares BOOM

[TroyG]

As a lot of yall already know I have been chasing a gremlin around for the past 2 months trying to figure out how to get my car back into the 6’s, well this weekend I finally got there. After spending some time replacing the rings and rejetting the carbs and resetting the fuel pressure on the nitrous I got the car back into the 6’s. This past weekend me and a couple friends went out to do some tnt at our local track and the car ran like a bat out of hell. Thank God all the hard work finally is paying off. On my last pass of the night me and a good friend were neck and neck , side by side having a great run when BOOM the motor goes. DAM IT not again. So I got back to the pits to find out that the motor through #4 piston out the top. This is the same thing that happened about 3 months back. This time I took time to go and pick up all the pieces that I could find, some of the cylinder and most of the piston. When I bent over to pick up the piston I could not believe what I saw. The rist pin pulled straight out the bottom of the piston.

After doing some checking around and talking to some other racers I have found out this week that AA’s have a problem with pulling rist pins out of the bottom of the pistons. I have received emails and pictures from other people with the exact same problem that I have been having. Everyone just thought is was a fluke deal and did not say anything about it. BTW the first time this happen to me it was # 1 piston. I had received a call about 3 weeks back from one of the distributors of the AA’s letting me know that they have been seeing some motors blowing up due to the rist pins pulling out the bottom. Like everyone sitting here reading this, I said the same thing ( That won’t happen to me ).

I have been in contact with Kona this week regarding this problem and the answer I get from him is ( AA pistons do not have a problem ). I’m not sure what happen but this is the first I have heard of this happening. ( I call BS ) Kona has offered to replace all my old pistons with a new set of AA’s. I told him to put himself in my place. Would you put another set of the same piston in your car after blowing up 2 motors because of the same problem. He responded, AA pistons are BETER than Wiseco’s and as good as JE’s so yes I would put a set in my car. Well that’s him not me, after running up a parts bill of more than $4500.00 in the past 4 months there is NO way I am putting a set of AA’s in my next motor. BTW my new Wiseco’s are on order along with case, rods, cylinders, bearings and now needing $400.00 worth of head work to repair my CB CNC 48x40’s.

Let me answer a few question before they get asked.
I am running a 2176
180hp all motor
249 on the juice Chassis Dyno
11.8 to 1 compression
75 shot of nitrous
Pulled the plugs and cut them open Look great
Timing is 34degs total pulling 4 out on the juice
22n 22f jetting on 8psi fuel pressure
NO detonation on plugs or pistons
Oil pressure is 45 at idle and 75 at 7000 rpms

One problem is Kona is wanting me to send my old parts back and send me a new set of AA’s to replace them. I will not use them on my new motor, so the only thing I could do is turn right around and sell them on the samba or ebay to recoop some of my money lost in this last motor. I will not take his deal for 2 reasons, 1 if I take his deal and sell them that puts me in the same position as him, selling parts that I know have a problem. Then when that guy blows his motor up, he will be coming looking for me. The second reason If I send him the bad parts to him that clears him of any wrong doing and there is no proof on my behalf. I’m not saying that Kona maybe or may not be at fault for knowingly selling defective parts, but I think I will just have to hold onto them for now. We are not talking about a part that was knowingly sold defective like a carb or intake, we are talking about a part that when it goes bad, does thousands of dollars in damage to a motor. No were in here am I saying that Kona runs a bad company or all his parts are defective, there not, its just 1 product that we know had a bad run at the manufacture within the last year or so that is causing a problem.

Here are pictures of the motor and the piston:

http://www.volkstalk.com/aa.htm

With that said I just thought everyone should be aware of the problem with the AA pistons being put out on the market.

Just my thoughts and opinions regarding the AA’s

[mharney]

That sucks Troy.

Kona, is there any indication that this has been worked out by AA, and how can we know if we have a set that have this problem? Is there some serialization or anything on the packages that will indicate whether they're bound to do this or not?

Is this likely to be an inherent defect in the material in those areas or casting design, or what?

[Glenn]

[TroyG]

Glenn
Ithink if the piston did what is was advertised to do I or we would not have had a problem.

( These are the NEW AA TRUE Forged Pistons. They have been tested and are stronger as JE and Cheaper too..They are Forged from 2618 T6 Aluminum which is the same strength as the JE Pistons )

Takin from
http://www.thesamba.com/vw/classifieds/detail.php?id=341135

[Glenn]

[TroyG]

Glenn
Im not sure were you came up with Im using 92's but my pistons are 94's.
78.4 x 94
78.4 DeMellow full circle w/m
Scat 5.5 rods
SLR reground lifter
FK89
Clevitte bearings
Arp 2000 bolts
AA pistons good upto 450hp as advertised
CB CNC 48x40 Heads
Dual Tapered C/M push rods

[Glenn]

[camch]

this is the 4th motor i have heard about in 2weeks including mine, i also had kona offer me the same deal but i told him i would rather have something else he had, for the same reason of selling bad parts,troy hate to hear about your engine mine was a 2275 turbo that let go at 4000,now i have wiesco's in my new motor

[TroyG]

lol Thats cool Glenn

Thanks for the cross link.....

Camch
Do you have any pictures of your old motor or of the piston that came apart on your motor.

[Jake Raby]

I have had the same thing happen with JE pistons, on more than one occasion.

What typically causes this is insane piston speeds, what rod length were you running?

11.8:1 with spray will make parts come unglued...... trust me, I am no fan of Chinese made parts-
_________________
Jake Raby
Raby Engine Development
www.rabyenginedevelopment.com
"I've never given anyone Hell, I just told them the truth and they thought it was Hell"

[TroyG]

Hey Jake I am running 5.5 chevy

[The Noof]

I'm just curious how the remaining 3 pistons look.Is there any distortion of the wrist pin bosses on them?
I'm running AA's in my 2232 turbo, at 22 psi as we speak.So far, so good.

[TroyG]

Noof
The other 3 pistons look just fine. Nothing, Normal, Clean burn, Bossed look fine, No oil starvation, No warning

[Jake Raby]

A 5.5 rod is middle ground for that stroke and those revs....
_________________
Jake Raby
Raby Engine Development
www.rabyenginedevelopment.com
"I've never given anyone Hell, I just told them the truth and they thought it was Hell"

[camch]

i am also running 5.5 rods,
i do have pics of the pistons but dont no how to up load on a post

[sszuch]

With the pistons so beat up, it is hard to tell, but it looks like a brittle failure. There won't be any visible signs of yielding in the other wrist pin bosses associated with this type of failure because crack propogation happens very quickly.

Interestingly enough, at 7000 RPM your piston weighs about 700 lb! It doesn't help that 2618 forging have a relativly low shear stress allowable and there is not much material supporting the pin boss on the sides. The effective bearing area is about 80* from the center of the wrist pin (40* from vertical to each side). This is a problem area because this is about where the pin boss looses cross sectional area from the pictures you posted. Small radii on the sides of the pin boss coupled with a large loss in cross sectional are increase the stresses dramatically.

[SRP1]

All I'm going to say is that every part has it's place, and every engine combo has it's needs. I feel that AA pistons are good pistons, however after seeing your combo I feel that your piston choice was incorrect and that it was not a fault of the piston. While there may be some fishy advertising going on as you claim I don't know. The fact remains that parts choice is key and engines especially race engines do blow up when pushed the engineering limits of the parts. I feel the AA pistons are a little on the heavy side and a little weak on pin support for your set up.

[TroyG]

SPR1
Ok I am always open for tips and tricks. You say that it is not the pistons fault or the piston is not to blame because it is the wrong piston choice. So if AA's are not made to handle 250hp nitrous or turbo or N/A motors as they are advertised then what in the heck are they good for. A piston that is said to be as strong as they say, should be able to handle the speed and head pressure of any 250hp motor weather it be any combination.

[TroyG]

I rewrote the ad the way it should read according to SPR1.

The way it reads right now !

These are the NEW AA TRUE Forged Pistons. They have been tested and are stronger as JE and Cheaper too..They are Forged from 2618 T6 Aluminum which is the same strength as the JE Pistons....They have Graphite Coated Slipper Skirts. Also has .100" Valve pockets on back of piston so that you can notch pistons for MAX Cam lift.

The way it should read !

These are the NEW AA almost Forged Pistons. They have been tested and are not as strong as Mahles, Wiseco's & not even in the same ball park as the JE piston, but are alot cheaper.They are Forged from 2618 T6 Aluminum which is the same strength as the 5hp Briges and Straton Pistons....Most but not all have Graphite Coated Slipper Skirts. Also has .100" Valve pockets on back of piston so that you can notch pistons for MAX Cam lift.

[beetleboy58]