81.5mm oversized Pistons

[markjane35]

Set of 81.5mm oversized Pistons with conrods to fit a 40mm crankshaft.
Good condition only covered about 2000 miles.
£50

[Donesy]

HI Mark,

I know it's a long shot but do you still have these?

Dave

[markjane35]

Hi Dave
I do still have these never got around to re-listing them.

[Donesy]

Great, We're way over budget on our engine build because of the re-bore. Would you take £30?? I'm happy to cover postage or come and collect.

D

[Donesy]

Just out of interest. are they genuine Toyota or after market?

[markjane35]

They are after market ones which the engine builder got for me. I paid £200 for them so was hoping for at least £50.

[Donesy]

No worries mate, DM me your email and I’ll get the cash over to you. Where abouts are you?


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[markjane35]

I am in Maidstone Kent. Before payment let me check them to make sure they are all ok.

[markjane35]

Hi Dave
Yep ok just to confirm that these are +0.50 oversized pistons which are fitted to Conrods for a 40mm crankshaft with 18mm
gudgeon Pins.

[Donesy]

cool. All our stuff is in the machine shop at the moment so I cant measure it. The BGB for the '88 aw11 gives 42mm crank pins but but I'm pretty sure it's right. We have 1989 Aw11 with red and black writing on the cam covers. And I think the 42mm cranks are pretty rare right?

Also, I'd be silly not to ask, how come they came out after just two thousand miles?

[superwhite90]

42mm cranks are common, 40mm are getting rare.

[markjane35]

The guy who rebored the engine overbored it to much so it was burning oil. Had to find another block and rebuild the engine but did not need the pistons as I used the existing ones.

[markjane35]

I also have both crankshafts 40 and 42 mm

[markjane35]

If it’s a 42mm crankshaft these will not fit.

[Donesy]

If it’s a 42mm crankshaft these will not fit.

I’ll have to make certain exactly what we have and get back to you. I don’t think we have the budget but how much for the 40mm crank.

Also, what did your engine builder bore it out to so we can avoid the same mistake.

Any benefits to the smaller stuff? Lighter I suppose but not so good if your chasing big bhp?


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[markjane35]

Hi Dave
I think that he just over bored it because when I checked the ring end gap after the problems with burning oil it was way out of spec. He should of only bored it out to take the 0.50 pistons. He has since closed down so can’t go back to him.
The 40mm crankshaft is 1kg lighter than the 42mm one.
Would sell the 40mm one for About £75.

[superwhite90]

Hi Dave
I think that he just over bored it because when I checked the ring end gap after the problems with burning oil it was way out of spec. He should of only bored it out to take the 0.50 pistons. He has since closed down so can’t go back to him.
The 40mm crankshaft is 1kg lighter than the 42mm one.
Would sell the 40mm one for About £75.

The 40mm cranks are lighter but weaker. They were found in the 3rib blocks which were also revised after 86 with 7 ribs along with the bigger crank.

The price offered is excellent and you will not find one cheaper in the condition it's in. I would have had the 42mm crank off of him if my crank was damaged.

[Donesy]

The 40mm cranks are lighter but weaker. They were found in the 3rib blocks which were also revised after 86 with 7 ribs along with the bigger crank.

The price offered is excellent and you will not find one cheaper in the condition it's in. I would have had the 42mm crank off of him if my crank was damaged.

I thought I might be able to find out what we have without having to wait until tomorrow via the miracle of the internet but there's way too much conflicting info out there.

What I can tell you is we have a 7 rib block and and a big-port head. I'm pretty sure that makes us a 42 but it seems there are few exceptions to this around the 86/87 model year.

One final question, do you know the compression ratio on those pistons? it seemed that changed around quite a bit too. but again, lots of conflicting info

[markjane35]

I think they are the lower compression ones as the crown is not raised.

[superwhite90]

I think they are the lower compression ones as the crown is not raised.

AW11 MR2 and ae86 corolla 4AGE with the big port heads have 9.4:1 CR Pistons. So All mk1 mr2s.

AW11 MR2 4AGZE big port come with 8.0:1 Pistons

Corolla ae92 4AGE with smallport has 10.3:1 pistons

Corolla ae92 4AGZE wig smallport has 8.9:1 pistons

[Donesy]

I think they are the lower compression ones as the crown is not raised.

You’re probably right but they’re aftermarket pistons so guess the vehicle specific factory CR specs are largely irrelevant.

Do you know what make they are? I might be able to look into it. It’s a lot of maths if I can’t find out the easy way.


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[markjane35]

Not sure of the make. They have a number on them. 16020.

[Donesy]

Cheers Mark,

http://www.aeu86.org/forum/Thread-Genuine-Toyota-pistons-for-4AGE-16v-3rib-bluetop

It looks like they are low comp ones. Very helpful of the manufacturer to put that number on despite not branding them!

I'm going to head over to the machine shop today, measure my crank and take a photo of my pistons. I might be imagining it but I'm sure mine had the dome on top.

[Donesy]

Mate, I hate to have messed you about but I think were going to have to pass on them.

If it was a like-for-like swap I would be very gratefully biting your hand off for them but after going to the garage I spoke to the main man and he reckons we only just in re-bore territory and I can see they are are a different CR. I think ours are 10.0 and yours are the standard 3-rib 9.4

4554

4555

This, combined with the crank swap making the whole engine bit of a mongrel, not to mention all the cash we'd be spending makes me think we might just be better off seeing if we can get a season out of her as she is and then make a plan when we can focus our spending on trouble shooting stuff like this. we've just got too many other parts of the project that need the cash at the moment.

I've just spent £400 quid i wasn't planning on spending on fibreglass panels from one of the other club guys!

once again, sincerest apologies mate

[jimi]

42mm cranks are not rare, they are standard on 1b engines.

[Donesy]

42mm cranks are not rare, they are standard on 1b engines.

Yeah, I realise that now, it’s the 40mm ones that are harder to find. I also had no idea about the all the rod configurations and all the different CR’s used across the lifetime of the 4age. Before this thread.

I can tell you all about a piston just from looking at the part number now though! [emoji851]


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[markjane35]

Toyota did like to mix things up with these engines. Dave not a problem about the pistons just glad to help.

[superwhite90]

Sorry I forgot they also did 10.1 pistons, I had a set come out of my spare engine which came from a Euro Spec Corolla GT . They are definitely 10.1

They are also very, very rare and worth quite a bit.

[Donesy]

Sorry I forgot they also did 10.1 pistons, I had a set come out of my spare engine which came from a Euro Spec Corolla GT . They are definitely 10.1

They are also very, very rare and worth quite a bit.

It took me ages to find out for sure but AW11's left the factory with them too. '13101-16080' is the part number on mine. I think '........16030' are also 10:1.

https://toyota-europe.epc-data.com/mr2/aw11r/2677/engine/1301/13101/

and check this out:

https://www.amayama.com/en/part/toyota/1310316080

these are the +0.5 version, In stock, in Japan. Shipped for 200 odd quid a set. That's half the price of the ones in the UK on ebay!.

Has anybody ever heard of or dealt with these guys before?? They seem pretty legit.