Notes:

Questions in red are from me.

Reply to this thread: http://www.toymods.org.au/forums/showthread.php?31201-3T-GTE-Tech

Items in square brackets are comments that I have added.

I tend to be a little pedantic and like to see concrete references.

No one should take offense!

Chamber volume (stock):

3T-GTE:                                  60 cc (Yellorolla)

“3TG”:                                     65 cc (Turbotoy) (note: “milled a couple of times”)

3T-C:                                       63 cc (wiseco- PDF)

Stock 3T-GTE piston dome:

6 cc (from memory) (YelloRolla)

3T-GTE Comp. height:             ???HELP

(I’m assuming that Compression Height is the same as the pin height – please confirm)

Rod Length: (From Radar – here)

2TC, 3TC, 3TG:                      4.850

Stroke: (From Radar – here)

2TC:                                        2.75

3TC, 3TG:                               3.070

Wiseco 3TC (with 63 cc head) (from the PDF)

* Made to order

3Jcelica: (here)

The wiseco pistons have a 2cc valve relief, and I have calculated an approximate static compression ratio of 8:1,

BRD also do custom pistons, so I am wondering whether a custom piston with a flat top (no valve relief) is worth the trouble. I calculate a flat top would result in approximately 8.2:1 static compression ratio at 87mm bore. Is this worth it? and does the 3tgteu need a valve relief (never had my head off) ?

My question:

Which Wiseco pistons, and what other numbers did you use in your calculations?

YelloRolla’s reply: (here)

I have used about 12 sets of the Wiseco piston - the ~8:1 comp ratio is up on what the factory spec of 7.8:1.
I have a set of pistons (2nd hand) SPS that are 86mm with the 6cc dome on them, c/w pins and rings for sale if you're interested. These use the RB30ET turbo rings.

My question:

Which Wiseco pistons (kit part number/specs?), and what head gasket thickness?

Turbotoy: (here)

Depending on bore, don’t the flat-top pistons give about 7:1 CR?

[+ other info copied above to chamber volume specs]

7t5-27: (here) [my Italics]

I try to do as much research as I can before buying parts and after talking with the folks at BRD and other places here stateside I ended up with Arias 87mm pistons with the 8.8 compression ratio for the 3tc. I was told they would work with the 2tg head with no problems, As I am still collecting parts I have yet to start building the motor but once I get around to it the piston to valve clearance will be checked and double checked. The crank is 3t and the rods are eagles, time will tell if it fits/works or not. Be safe

Diz44y: (here)

Quick question relating to pistons. I recently purchased some 87mm forged arias for my 3TGTE and they arrived today (I specifically asked for 3TG pistons). The problem is that they state they are for a 3TC. I read in another thread somewhere that the pin height is the same for the 3TC and 3TG but the valve reliefs aren't (which may cause a problem). I think YelloRolla mentioned (in reference to weisco pistons) that because the valve reliefs are oversized for the 3TC weisco pistons then there won't be an issue when using them in a 3TG. Does the same apply to the Arias? How can i tell if the valve reliefs are oversized?

These are the specs for the pistons [added to table above]
Displacement:1854.75
Finished bore: 87.00
Stroke: 77.98
Rod length: 122.9
Comp height: 34.93
Compression: 8.50
Pin diameter: 22.0
Top groove: 1.5
2nd grove: 1.5
Oil groove: 4.0
Clearance 0.089

Dome CC: 8.80

Will these suit my application? As you can tell I'm no mechanic and I have plenty of noob questions but I refuse to give up on my TA63

YelloRolla: (here)

I will need to check, but from the top of my head the rod length seems to be quoted incorrectly.      [note: rod length in post above is basically same as quoted by Wiseco]

Dizzy: (here)

Thanks Jas. I shot an email back to them and the response was this"

"Hi Josh, a little known secret is that the 3TC and 3TG bottom end
components are the same.
You will be fine.
As with any engine, build you should "always" check valve to piston
clearance. I suggest you do the same for your comfort and peace of mind.
But I have done tons of these builds and sold tons of these same rods and
pistons for 3TG with no problems."

I'll double check that I haven't accidentally made a transcription error tonight.

[7t5-27 replied that he has the same pistons + Eagle rods, yet to be fitted]

[discussion on bringing Diz44y’s CR down via cam timing/gasket/chamber milling was not included – afaik actual CR was never confirmed (measured)]

turbotoy: (here)

Well let me remember. I had stock intake manifold, stock exhaust manifold, ct-20 with an upgraded super 60 compressor wheel, 8.5:1 compression, running .8 bar boost 276 rwhp and 270 torque with 222 cams. Unfortunately I didn't get a chance to do a before and after of the stock cams compared to the 222's.

Steeko: (here)

[refers to brdracing.com website]

Wiseco Low Compression Turbo Pistons
$439.00
Wiseco Pistons Are Available For 2TC and 3TC In 86MM(.040), 87MM(.080), 88MM(.120) and 89MM(.160)
7.1:1 7.5:1 8.1:1 and 8.5:1 Available

[note: if each of those pistons is available in each compression ratio, then wouldn’t that be a total of 16 different low compression piston sets? That seems like a lot.]

Steeko: (here)

I'm using 86mm Wiseco pistons and eagle rods from BRD.

Steeko: (here)

Got some more info from mechanic and now ready to order pistons.

I read that the 3TGTE has a stock compression ratio of 7.5:1. [this is wrong, it is 7.8:1]
Wiseco pistons come in 7.5:1 and 7.1:1, just wondering which is better to use?
To go lower than stock? As I read that lower compression is better on a turbo engine.

AE25:  (here)

stock is 7.8:1 compression afaik.
It seems back in those days, using cast pistons with low compression to make them boost friendly was the way to go. But with forged pistons, unless you're running stupidly high boost, then see if you increase compression for better off boost drivability. Are there any 8.5:1 pistons available?

[There is one more reply stating the same specs about pistons that BRD lists as available]

ACT blue 22: (here)

I built an engine with the 8.5 pistons and drove it n/a and it ran awesome. I'm planning on running big boost and the 8.5 I'll have no trouble doing it. I have another mate running the same pistons on stock turbo and is pushing comfortably 150 to 160 rwkw on 14 psi boost. Definitely go the 8.5.

Question for ACT blue 22: What pistons did you go for? Part number, specs, etc?

Turbotoy: (here)

I tried 8.5 pistons and ended up dropping my compression to 8.0 for more boost.

[see below for context]

YelloRolla: (here)

Turbo Toy,

What was the boost limit and power level you were you finding at your 8.5:1 ratio ? And what management were you using. It might also pay to define pump fuel, Over here we get 98 Octane (98RON) pump fuel and a couple of Octane points makes a big difference.

The old low compression for boost theory is about as current as the technology for single cam push rod engines and since Steeko is not looking for "Big Power" I would have personally gone with the 8.5:1 items for better off boost performance.

My Turbo T series is around 8.2:1 and while it has never fired a shot there are a number of Engines in this configuration turning high boost levels with very nice results.

Turbotoy: (here)

I use a walbro 255 hp with 550cc injectors, Management with the 8.5 pistons was a Haltech E6S. I made 267 HP at 1.2 bar boost with stock intake and exhaust manifolds, 2tg 222 cams. We use 93 octane here in the states. The reason I think the "old low compression for boost theory" is old is because of the advances in turbo intercooler and most of all engine efficiency. I wasn't necessarily telling him to go with the 8.0:1 pistons. Just telling him my experience. I honestly think he would be fine with the 8.5:1 pistons. That is what I started with. For a street car they will be great!! However I got used to the power and wanted more and turned up the boost till I "needed" 8.0:1 pistons

Steeko: (here)

Am finding dealing with BRDracing.com very trying. I have to ask the same question three times, they just always reply with "pistons are $439 thanks".

Anyway quick question. Do the stock 3TGTE pistons have a curved top or flat top? As the Wiseco pistons are flat top, not sure if this is a problem as it seems quite a few people here have used the Wiseco forged pistons before.

Also apparently BRD only has the 7.8:1 pistons, anything else costs more and will be custom made. This is all contradictory to their website

YelloRolla: (here)

The stock 3T piston has a dome of 6cc (from memory). Josh recently delivered me a set of pistons and rods that I believe that he bought from BRD that are the Arias 8.5:1.

The Wiseco flat top pistons work pretty well in the scheme of things, the static CR is raised somewhat by having 2mm larger bore, but it still doesn't get it back to the 7.8:1.

The drivability (if there is such a word) is still pretty good off boost because the stock cam timing is sensible, coupled with a decent modern turbo and well thought out exhaust manifold, you wouldn't really know from the driver's seat.

Question: Has anyone done the measurements to actually see what the CR with those Wiseco flat-tops (presumably those in the table) actually comes out to?

If someone has, please let us know and provide the kit number and any variables such as headgasket thickness.

Reply to this thread:

http://www.toymods.org.au/forums/showthread.php?31201-3T-GTE-Tech