Aftermarket "OEM style" pistons

[Rogue-AE95]

Thought I would post this. I just ordered a set of DNJ 0.5mm oversized 10.3:1 pistons for my engine build. They look fine as far as that goes. I'm not expecting to build a monster engine using these, although I do want to send these out to get the tops coated. I'm going to order Toyota rings and hope that will help with longevity (vs some other brand's rings which might not last as long).

It's too bad they have the slots on the sides instead of a series of holes like the 8.9:1 GZE pistons have. I suppose it's because these are made to OEM standards... well, except for missing the top coating.















I'm wondering if anyone knows what those spots are in the last pic.

[jondee86]

Looks like some liquid dried up in there. Try scuffing the spots
with a bit of Scotchbrite and see if the colour comes off.

Cheers... jondee86

[oldeskewltoy]

very interesting....

I'm sure it was done by accident.... but there is an oiling feature on the DNJ piston NOT on the OEM one....

The small oiling hole inside the oil ring groove over the wrist pin hole... is NOT there on a factory high comp piston... it IS there on the early TVIS pistons that used a press fit pin.

That small hole is designed (on the 18mm TVIS piston) as part of the oiling used to lubricate the wrist pin.


btw... from a visual standpoint... they look significantly better then a set of aftermarket TVIS pistons I recently saw........

[Rogue-AE95]

Interesting, thanks for letting me know. If you look at the inside view I posted, that hole that goes through the wrist pin area connects to that smaller hole. I checked using a bright LED flashlight.

It's hard to capture in a pic, but the inside (other than those dark spots) looks as though it has some silver overspray. I'm wondering if these were "painted" with some kind of coating, or if it's something to do with the casting process. The 8.9:1 GZE pistons I have show a sort of swirled pattern inside, which must have to do with the forging process:
viewtopic.php?f=13&t=452#p1025

[Deuce Cam]

How do the price of these compare to oem?

[Rogue-AE95]

These were about $80 shipped. OEM are a lot more, but OEM are also coated on top... and OEM quality. I'm doing something of a budget build, so that's why I didn't spring for OEM pistons. Though I am going to use an OEM headgasket. Now that I have an OEM and an "ITM" brand gasket, I can see the difference.

From a little digging I've done, the '88-'91 Honda Prelude Si engine uses the same bore & ring thickness as the 4A-GE smallport. But I don't know about the depth of the grooves (width of the rings). NPR brand rings are supposed to be OEM quality. Here's hoping.

Edit: here's a link to an old C4AG topic:
http://forums.club4ag.com/zerothread?id=43537

[yoshimitsuspeed]

I'm fairly certain only GZE pistons are coated.

[burdickjp]

I wonder if "0.30 mm decked" means they have a shorter compression height.

I'm fairly certain only GZE pistons are coated.

Of all the 4A pistons I've seen, you are correct.

[Rogue-AE95]

I wonder if "0.30 mm decked" means they have a shorter compression height.

That's possible. But then I wonder if the OEM (oversize) pistons are the same.

I'm fairly certain only GZE pistons are coated.

Of all the 4A pistons I've seen, you are correct.

Every pic I've seen of OEM smallport pistons, they were coated on top. The set that I bought from a member here (which were damaged and I sent back for a refund) were coated...

[oldeskewltoy]

Every pic I've seen of OEM smallport pistons, they were coated on top. The set that I bought from a member here (which were damaged and I sent back for a refund) were coated...

you are correct...

When I assembled the engine for my black coupe(back around 2000) I bought brand new Toyota high comp pistons... and they are coated down to the first ring




concerning the .30mm I was thinking the same thing... and that MIGHT make sense... for decking a block on a rebuild isn't unheard of... and .2mm (.008")would be about what a clean up cut on a block would be...

Rogue... if you can.... assemble the piston on the rod with bearings... and fit the piston(don't fit it dry)... then with the piston at its TDC... measure the deck. For best accuracy... measure the deck inline with the wrist pin...

[Rogue-AE95]

Thanks for confirming. I was hoping I wasn't crazy (about the coated tops).

I was thinking about doing just that with these pistons. But will these oversize pistons fit the 81mm bore? I understand not fitting them dry. I was thinking that the cylinder walls aren't opened up enough for an overbore piston to slide in. I suppose another way of going about this would be to measure from the top of the wrist pin (with a pin partially installed) to the top edge of the piston? I've got calipers so I can take a pretty accurate reading that way. It would be good to see if someone out there with OEM pistons (standard and overbore) can do the same thing.


Edit: using calipers, I carefully measured the top of the wrist pin bore to the top surface of the piston: ~1.97mm. The top dome was ~1.6mm from the top surface of the piston.

[Rogue-AE95]

I edited my post above with these O/S piston measurements.

Rings & things. I measured the widths of all the rings with metric calipers, and double-checked the thicknesses as well. The Beck Arnley rings are "for" the smallport, whereas the NPR rings are for the Honda B20A engine. To the left are the OEM rings that I ordered with my 8.9:1 GZE pistons over a year ago. All are "made in Japan."

[deriak]

Cool write up.

I got a question though, instead of creating another piston thread, I thought I would just ask here being we are on the same topic.

I sent my 3rib 4age motor to the machine shop, having the head and block shaved (small damage, I will know the exact specs when I pick it up) and the cylinders were slightly egg shaped, .090 being the worse. I gave the go ahead to bore it out to .020 over. This is just motor I am building and probably going to resale to fund my other project. I got it free for helping a friend swap a 4agze in his 85 mr2.

With that said, what Brand pistons that has .020 available would you guys recommend.. Also being a 4age, should I put low compression pistons for boost, high compression for an N/A build, or just go with OEM piston? Which would have a better turnover for selling in the 4age market?

One more question, is there a difference between the 3 rib and 7 rib internals (pistons, bearings, rods, etc)?

thanks

[gotzoom?]

If the shop hasn't already started working on the block, you should tell them to hold off until you have pistons. You normally give them the pistons and block at the same time, then specify the piston clearance and they measure the pistons and bore to your spec.

[mad_86]

rogue- how are you liking those pistons so far?? they look pretty good for the price, you have update??

[Rogue-AE95]

No updates, sorry. I have almost everything needed for the engine rebuild. Just need to save up for machine shop work, aftermarket ECU / wiring / sensors, and possibly head porting. I never have enough money saved up to do anything "expensive."

[mad_86]

I'm running these also, got the motor up and
Running stock hc block specs, large port head
Stock everything. So far feels good gonna wait
A bit before I push it, wish I would of coated them
Before assemble short block at a local machine shop.

[yoshimitsuspeed]

For anyone looking for pistons I have a great deal on Arias pistons now. I can do $480 for a set of pistons and rings. Definitely not as cheap as the DNJ but not bad considering OEM with rings are about $420 through Lithia.
One is perfect to get you around 10.4-10.8:1.

[Rogue-AE95]

I think I saw those on your FB post. That is a great deal, and makes me wish I had waited a little longer before buying anything. All the Arias pistsons are forged?

mad86, glad to hear the pistons are fine. They seem fine just looking at them, as far as build quality goes. Were you able to get a good set of rings also?

[yoshimitsuspeed]

I think I saw those on your FB post. That is a great deal, and makes me wish I had waited a little longer before buying anything. All the Arias pistsons are forged?

Yep

[burdickjp]

After seeing what Arias passed off as 20v pistons, I wouldn't trust them unless I put hands on whatever they were offering.

[yoshimitsuspeed]

After seeing what Arias passed off as 20v pistons, I wouldn't trust them unless I put hands on whatever they were offering.

Unfortunately they haven't had a lot of good info on the 4AGE and I think this lead to less than optimal pistons and for the 16v horribly off specs.
With that said I finally got pics of all their 4A pistons and their 20v pistons don't look horrible to me. They don't offer a high comp piston which I find odd but I may be able to change that soon.

Low comp piston looks more or less like a GZE piston with 5 way oversized valve reliefs. Still nothing that should cause any issue.


Again the valve reliefs on the 10.5:1s seem too big to me even for oversized valves.

I will be trying to work with them to tweak some of these things and get their pistons a little more optimized.
All in all I find the 16v 9.5 and 10.5:1 pistons to be about as good as anything on the shelf out there. The 12.5 I'm not so fond of but who is going to run a 12.5:1 shelf piston?

I don't think I will ever run anything as low as 8.9:1 again but I might consider running their 10.5:1s in a budget turbo build.

BTW some related stuff I have been working on lately to help people know what they are really getting vs what's advertised when it comes to aftermarket pistons.

http://www.matrixgarage.com/content/com ... e-and-7age

http://www.matrixgarage.com/content/4ag ... ormation-0

[Rogue-AE95]

viewtopic.php?f=13&t=15975

I figured this topic was as good as any to ask this, since neither of these "aftermarket OEM style" pistons (Dana in the link above, DNJ in mypost) do not have the top/dome coating that the actual OEM pistons have. Why did Toyota coat the piston domes? I know it sounds like a stupid question but I really want to know. And I know this will sound equally stupid to suggest, since they're different companies and different engines, but... Honda's performance oriented engines do not have a piston dome coating from factory. (Some, however, do have skirt coatings.) This includes the B18C5 (Type R) which has a slightly higher CR of 10.6:1 compared to the smallport's 10.3:1.

Are the dome coatings another case of harmless (perhaps helpful) "over engineering" that the aftermarket companies decided were not necessary?

[oldeskewltoy]

Are the dome coatings another case of harmless (perhaps helpful) "over engineering" that the aftermarket companies decided were not necessary?

likely....... Toyota had to have a 50k mile warranty... DNJ and Dana... nothing except maybe 90 days

[Abe Cruz]

Any recent updates regarding these pistons? Im considering them for my missle project because even used 16v high comp pistons run for a lot and the condition on them isn't the best.

Just curious to see if anyone is having any issues also.

[Rogue-AE95]

Unfortunately I changed my mind... again... I'm going to do a 7A-GE build with different pistons. I've shelved doing a 1.6l build for a while, but if I resumed it, I'd probably end up getting custom aftermarket pistons around 10:1 comp and turbo it.

[Rogue-AE95]

I'm not trying to get under your skin, just wanting to know... if the 8.9 GZE pistons aren't forged, why do they look so different than the other stock 4A-GE pistons?

Also there was this old post about GZE / GE piston composition:

http://forums.toymods.org.au/index.php? ... 6ab1a17549

[oldeskewltoy]

to admin/moderator who deleted these posts... you forgot the instigator... so I deleted it too.............

[Rogue-AE95]

I was wondering what happened. I was hoping there would be more info posted to back up what he was saying. I've heard more than once that the smallport/GZE piston domes were not ceramic coated, but hard anodized. I briefly had a set of pistons in my possession (they are with my engine builder now) for another engine that were definitely hard anodized, as I called up the piston manufacturer and asked them. Those tops looked different compared to the 8.9:1 GZE pistons I have. But I'm getting a little off this original topic now...

[jondee86]