Supercharging questions - Page 2

te51levin · 10-08-2009, 03:53 PM

Wow, that's definitely not a supercharged piston. That looks to be a smallport piston, which makes 10.3:1 compression with a stock head gasket, stock head, etc - unless it's an aftermarket unit of some kind.

Repiv · 10-08-2009, 05:10 PM

It's aftermarket most likely. He told me it was a TRD piston and it looks a lot like the piston in this thread http://www.aeu86.org/viewtopic/stran...s-4a-ge/t/6212.

The weird part is it was just about as fast as my girlfriend's 1986 AW11 i'm driving currently. Then again I never really gave it hell at the top end.

IDon'tKnow · 10-08-2009, 05:20 PM

Using a thicker head gasket isn't going to shave more than .5:1 for you.

te51levin · 10-08-2009, 05:31 PM

Quote:

Originally Posted by Repiv

It's aftermarket most likely. He told me it was a TRD piston...

Grab a wire brush and some acetone and see if you can find any identifying marks stamped in the top of the piston. You got me awfully curious now...

Repiv · 10-08-2009, 06:05 PM

"2" "CD" and "0.50" is all I can find so far on the piston.

te51levin · 10-08-2009, 06:18 PM

I believe, although I am not positive, that those are OEM smallport pistons. They're the same size as my cylinders, so if you decide you want to replace them in favor of something else, I might be interested in those. I could always use a little more compression

Repiv · 10-08-2009, 07:01 PM

I'm already way deeper than I wanted to be in this engine. Replacing pistons and rebalancing doesn't sound fun to me.

te51levin · 10-08-2009, 09:13 PM

The Toyota pistons I've seen have been within one gram of each other right out of the box. They're pretty consistent. I don't think you'd need any rebalancing, so long as you have four of the same type of piston.

Repiv · 10-09-2009, 10:17 AM

Interesting. That changes things. What would you be willing to buy these for?

At this point i'm really glad I bought a shell that came with a completely torn down motor. :P

te51levin · 10-09-2009, 09:36 PM

Quote:

Originally Posted by Repiv

Interesting. That changes things. What would you be willing to buy these for?

Good question, actually. The only thing that concerns me is that I am not positive they are OEM. I see aftermarket replicas on eBay going for about $65 a set. How about we take this back up after you pull one out and look for identifying marks on the skirt and/or underneath?

te51levin · 10-10-2009, 02:35 PM

Just found something halfway useful. If the pistons are OEM, they should have the word TOYOTA cast into them in the side, near the wristpin hole. I'll attach some pics.

Also, looking at the TRD Japan website, I don't see any 81.5mm pistons, and the "0.50" mark in the piston crown almost certainly indicates an overbore to 81.5mm (81.0mm is stock).

How exactly is the car's existing GZE "blown"? What's wrong with it? In other words, do you really need the NA's pistons, block, etc?

Repiv · 10-11-2009, 11:41 PM

It spun two bearings. I really don't know how much further I want to go with this. I was planning on just dropping in this engine and being done with it but I'm so far beyond that at this point. I don't think I can even use the pistons from the other block because of bore differences and I can't afford to build up the other block.

te51levin · 10-12-2009, 01:45 AM

Quote:

Originally Posted by Repiv

It spun two bearings.

Oh, that's perfect! Assuming the SC block is not damaged, you can keep the pistons and rings from the SC and just swap in the crank and rods from the NA engine. Or did the block get damaged too?

Jackstand Queen · 10-12-2009, 02:59 AM

Repiv . . . if you are tearing down and rebuilding an engine for the first time . . . don't rely solely on the manual. You'll probably need someone who has rebuilt a few to assist you. There are as many pitfalls as there are parts in rebuilding an engine.

Also, don't overlook replacing the tired valve seals, worn valve guides, and check the valves are seated airtight in their seats.

A good machine shop can turn down the spun journals on the crank, and you can put in just two oversized bearings.

I'm just saying it ain't over till the fat lady sings.

espguitarist33 · 10-12-2009, 04:21 PM

unless your crank looked like mine that pushed the surface metal over the oil hole and sealed it with a ginourmous groove going around it...it'd prolly look like a tooth pick if machined smooth

toyotaspeed90 · 10-12-2009, 06:24 PM

the question becomes... is it even a gze block? Not much difference between a gze and a smallport n/a block....

second... most Toyota pistons, if "toyota" isn't stamped on the skirt, will say "ART" on the underside of the piston (only way to tell stock latemodel gze pistons)

I had a set of the cheap cast ebay pistons in my 7a.... had no problem with the pistons or rings at all....

you can see where the OE shows "toyota" and the cast does not

the top of the cast looks IDENTICAL (even the little nub) to the oe pistons.

10-10-2009, 02:35 PM	#31 (permalink)
te51levin Lithia Toyota Parts Join Date: Oct 2005 Location: Oregon Posts: 1,924 Thanks: 33 Thanked 146 Times in 125 Posts My Google Map iTrader Rating: (126/100% )	Just found something halfway useful. If the pistons are OEM, they should have the word TOYOTA cast into them in the side, near the wristpin hole. I'll attach some pics. Also, looking at the TRD Japan website, I don't see any 81.5mm pistons, and the "0.50" mark in the piston crown almost certainly indicates an overbore to 81.5mm (81.0mm is stock). How exactly is the car's existing GZE "blown"? What's wrong with it? In other words, do you really need the NA's pistons, block, etc? Attached Thumbnails Last edited by te51levin; 10-10-2009 at 02:39 PM. Reason: more questions...

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10-08-2009, 03:53 PM	#21 (permalink)
te51levin Lithia Toyota Parts Join Date: Oct 2005 Location: Oregon Posts: 1,924 Thanks: 33 Thanked 146 Times in 125 Posts My Google Map iTrader Rating: (126/100% )	Wow, that's definitely not a supercharged piston. That looks to be a smallport piston, which makes 10.3:1 compression with a stock head gasket, stock head, etc - unless it's an aftermarket unit of some kind.

10-08-2009, 05:10 PM	#22 (permalink)
Repiv No Skills Join Date: Jan 2009 Posts: 16 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	It's aftermarket most likely. He told me it was a TRD piston and it looks a lot like the piston in this thread http://www.aeu86.org/viewtopic/stran...s-4a-ge/t/6212. The weird part is it was just about as fast as my girlfriend's 1986 AW11 i'm driving currently. Then again I never really gave it hell at the top end.

10-08-2009, 05:20 PM	#23 (permalink)
IDon'tKnow but I can find out. Join Date: Sep 2009 Location: Huntsville, AL Posts: 132 Thanks: 4 Thanked 2 Times in 2 Posts iTrader Rating: (1/100% )	Using a thicker head gasket isn't going to shave more than .5:1 for you.

10-08-2009, 06:05 PM	#25 (permalink)
Repiv No Skills Join Date: Jan 2009 Posts: 16 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	"2" "CD" and "0.50" is all I can find so far on the piston.

10-08-2009, 06:18 PM	#26 (permalink)
te51levin Lithia Toyota Parts Join Date: Oct 2005 Location: Oregon Posts: 1,924 Thanks: 33 Thanked 146 Times in 125 Posts My Google Map iTrader Rating: (126/100% )	I believe, although I am not positive, that those are OEM smallport pistons. They're the same size as my cylinders, so if you decide you want to replace them in favor of something else, I might be interested in those. I could always use a little more compression

10-08-2009, 07:01 PM	#27 (permalink)
Repiv No Skills Join Date: Jan 2009 Posts: 16 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	I'm already way deeper than I wanted to be in this engine. Replacing pistons and rebalancing doesn't sound fun to me.

10-08-2009, 09:13 PM	#28 (permalink)
te51levin Lithia Toyota Parts Join Date: Oct 2005 Location: Oregon Posts: 1,924 Thanks: 33 Thanked 146 Times in 125 Posts My Google Map iTrader Rating: (126/100% )	The Toyota pistons I've seen have been within one gram of each other right out of the box. They're pretty consistent. I don't think you'd need any rebalancing, so long as you have four of the same type of piston.

10-09-2009, 10:17 AM	#29 (permalink)
Repiv No Skills Join Date: Jan 2009 Posts: 16 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	Interesting. That changes things. What would you be willing to buy these for? At this point i'm really glad I bought a shell that came with a completely torn down motor. :P

10-11-2009, 11:41 PM	#32 (permalink)
Repiv No Skills Join Date: Jan 2009 Posts: 16 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	It spun two bearings. I really don't know how much further I want to go with this. I was planning on just dropping in this engine and being done with it but I'm so far beyond that at this point. I don't think I can even use the pistons from the other block because of bore differences and I can't afford to build up the other block.

10-12-2009, 02:59 AM	#34 (permalink)
Jackstand Queen Cage Fighter Join Date: May 2008 Posts: 677 Thanks: 52 Thanked 56 Times in 53 Posts iTrader Rating: (1/100% )	Repiv . . . if you are tearing down and rebuilding an engine for the first time . . . don't rely solely on the manual. You'll probably need someone who has rebuilt a few to assist you. There are as many pitfalls as there are parts in rebuilding an engine. Also, don't overlook replacing the tired valve seals, worn valve guides, and check the valves are seated airtight in their seats. A good machine shop can turn down the spun journals on the crank, and you can put in just two oversized bearings. I'm just saying it ain't over till the fat lady sings.

10-12-2009, 04:21 PM	#35 (permalink)
espguitarist33 Cage Fighter Join Date: Nov 2008 Location: west chester PA Posts: 415 Thanks: 4 Thanked 5 Times in 5 Posts iTrader Rating: (2/100% )	unless your crank looked like mine that pushed the surface metal over the oil hole and sealed it with a ginourmous groove going around it...it'd prolly look like a tooth pick if machined smooth

10-12-2009, 06:24 PM	#36 (permalink)
toyotaspeed90 No Skills Join Date: Jun 2006 Location: Bellingham, WA Posts: 422 Thanks: 0 Thanked 32 Times in 32 Posts My Google Map iTrader Rating: (0/0% )	the question becomes... is it even a gze block? Not much difference between a gze and a smallport n/a block.... second... most Toyota pistons, if "toyota" isn't stamped on the skirt, will say "ART" on the underside of the piston (only way to tell stock latemodel gze pistons) I had a set of the cheap cast ebay pistons in my 7a.... had no problem with the pistons or rings at all.... you can see where the OE shows "toyota" and the cast does not the top of the cast looks IDENTICAL (even the little nub) to the oe pistons.