bored block

camdiddy · 11-17-2009, 03:56 AM

Hola!

The block I am looking at buying from someone for my rebuild has been bored 40 over and I was wondering if I am able to use stock gte pistons or if I will need to buy different spec pistons. If so, do u guys have any recommendations for pistons that wouldnt destroy my wallet?

Thanks

MA70-3.0GT · 11-17-2009, 05:10 PM

Err, if I remember correctly .40" is over 1mm oversize so no, I'd very much doubt standard pistons would last more than a couple of days before rattling themselves to death. Generally I use Wiseco pistons for my rebuild work. Not 100% they do them for this engine but it's likely as they do most applications & if it's not listed then you can usually give them the spec. you require & they have something suitable in stock.

No doubt someone with more experience of these motors has a different recommendation for you if you give it a while, but personally I've never had any issues with Wiseco in quality or pricing...

two-step-n · 11-17-2009, 05:35 PM

the block is bored .40 over there for you will need .40 over size pistons

cre · 11-17-2009, 07:34 PM

I think Toyota sells pistons in larger sizes for bored engines... .040" may be the largest they carry though. If anyone feels like it you could research the part numbers on this page: http://www.cygnusx1.net/Supra/Librar...rts/13101.aspx

Regardless, I'd still go aftermarket. If you're going to have it all apart the wallet is the only reason to reconsider forged internals. At this point I'd go with some GOOD pistons (wiseco or probe, for example) and forged rods.

If money's tight, NPR makes a stock replacement which is available with a Teflon coating. They're affordable and will perform well enough for slightly modded cars. They are still cast though and you have them balanced and matched, but they're pretty good.

camdiddy · 11-18-2009, 12:43 AM

Cool. Thanks for the info. Looks like I am going to have to set aside a little more cash for this thing. and I assume I will need aftermarket rods to go with the pistons as well, correct?

cre · 11-18-2009, 12:50 AM

No point in sticking with stock rods if you're going with premium pistons.

Actually, the original rods are more likely to fail than the original pistons would have been. New OEM rods would be fine, but I'd have them balanced and cryo treated... depends on your goals with this engine.

camdiddy · 11-18-2009, 01:00 AM

Yea i agree. Here's the situation, I found someone selling a running 7mgte motor w/ r154 (~110,000 miles), t4 turbo kit, extra block bored .040, and extra polished crank all for a decent price. I have a 86.5 7mge auto that I will be swapping this into so I'm just scoping out what all extra I am going to have to buy to build and swap the motor. Right now it looks like im going to need...

forged pistons and rods
wiring harness/ecu
gaskets
intercooler
driveshaft
and whatever else needs replaced on the gte and trans

corrosivecopper · 11-18-2009, 04:22 PM

When it comes to rods that's not entirely true.. Toyota makes a pretty solid engine from the start, and depending on cash flow and how far you want to take the engine, it could be more cost effective to have the stock rods shot peened, assuming they're in decent shape to begin with. That could make them as strong, if not stronger than the aftermarkets. Not too many companies are out there with rods for these engines, for sure nothing that is really reasonably priced. If you must, better to find a package deal with forged pistons. Not sure about down in the US, but it's somewhat rare to find a shop around here who'll do them, but they're out there. Good luck!

cre · 11-18-2009, 08:26 PM

Quote:

Originally Posted by CRE

...the original rods are more likely to fail than the original pistons would have been. New OEM rods would be fine, but I'd have them balanced and cryo treated...

In saying "the original rods" I was referring to the 20yo old rods which came with the car (we'll forget the fact that I was comparing the longevity of the 20yo pistons to that of the 20yo rods, it was merely academic anyway). With cryo treatment or shot peening (or both) they (new, OEM rods) can indeed prove very robust. Shot peening does not give you an end product which is as tough as a rod which was forged... in the absolute simplest of descriptions think of shot peening as forging after the fact. Shot peening is only surface deep; Forging goes all the way to the core.

What he needs is going to depends entirely on his long term power goals... yeah, I've heard of people putting down massive amounts of power on stock rods... BUT I've seen a LOT more people post pictures of their stock rods protruding from the engine or a hole where it had.

You can find sets of high end pistons and rods for a decent price here in the U; Sometimes for just a little more than the pistons themselves would have cost. It's all a matter of shopping around, waiting and sometimes just asking the right person... watch for group buys on all the different Supra related forums.

camdiddy · 11-18-2009, 09:24 PM

Thanks for the responses guys. I am shooting for a reliable 350-400 whp car and based on the reading i've been doing, some new oem pistons and rods should be fine for this set up. If i had money in da bank, yea i would definately go for the forged set, but spending a grand on internals isn't in my budget right now unless i can find a good deal.

...so are the original/stock gte pistons forged or cast?

11-17-2009, 03:56 AM	#1
camdiddy Stock Join Date: Jun 2009 Location: Avon, IN Posts: 6	bored block Hola! The block I am looking at buying from someone for my rebuild has been bored 40 over and I was wondering if I am able to use stock gte pistons or if I will need to buy different spec pistons. If so, do u guys have any recommendations for pistons that wouldnt destroy my wallet? Thanks

11-17-2009, 05:10 PM	#2
MA70-3.0GT 12psi boost Join Date: Oct 2009 Location: Crewe, England Posts: 356	Err, if I remember correctly .40" is over 1mm oversize so no, I'd very much doubt standard pistons would last more than a couple of days before rattling themselves to death. Generally I use Wiseco pistons for my rebuild work. Not 100% they do them for this engine but it's likely as they do most applications & if it's not listed then you can usually give them the spec. you require & they have something suitable in stock. No doubt someone with more experience of these motors has a different recommendation for you if you give it a while, but personally I've never had any issues with Wiseco in quality or pricing... __________________ '89 MA70 Supra GT aero 3.0turbo JDM, Rebuilt motor, K&N intake, 3" stainless turbo-back. New turbo and braided line kit... '89 Honda NC27 400, NC23 cams, open pipe, PC36a shock & possibly Showa USD forks... '83 Yamaha 29R XJ750E-II, number 69 off the line, only runner in the country? Original except Koni shocks '95 Honda PC26 CB500R, Winter hack, hateful, trying to sell it I'm not paranoid, they really ARE after me!!!

11-18-2009, 12:43 AM	#5
camdiddy Stock Join Date: Jun 2009 Location: Avon, IN Posts: 6	Cool. Thanks for the info. Looks like I am going to have to set aside a little more cash for this thing. and I assume I will need aftermarket rods to go with the pistons as well, correct? Last edited by camdiddy; 11-18-2009 at 12:47 AM.

11-18-2009, 04:22 PM	#8
corrosivecopper Stock Join Date: Jul 2009 Location: Bonnyville, Alberta, Canada Posts: 20	When it comes to rods that's not entirely true.. Toyota makes a pretty solid engine from the start, and depending on cash flow and how far you want to take the engine, it could be more cost effective to have the stock rods shot peened, assuming they're in decent shape to begin with. That could make them as strong, if not stronger than the aftermarkets. Not too many companies are out there with rods for these engines, for sure nothing that is really reasonably priced. If you must, better to find a package deal with forged pistons. Not sure about down in the US, but it's somewhat rare to find a shop around here who'll do them, but they're out there. Good luck! __________________ 87 Supra 7MGTE Stock.. for now

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11-17-2009, 05:35 PM	#3
two-step-n 3" Exhaust Join Date: Oct 2009 Location: mesa az Posts: 51	the block is bored .40 over there for you will need .40 over size pistons

11-17-2009, 07:34 PM	#4
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	I think Toyota sells pistons in larger sizes for bored engines... .040" may be the largest they carry though. If anyone feels like it you could research the part numbers on this page: http://www.cygnusx1.net/Supra/Librar...rts/13101.aspx Regardless, I'd still go aftermarket. If you're going to have it all apart the wallet is the only reason to reconsider forged internals. At this point I'd go with some GOOD pistons (wiseco or probe, for example) and forged rods. If money's tight, NPR makes a stock replacement which is available with a Teflon coating. They're affordable and will perform well enough for slightly modded cars. They are still cast though and you have them balanced and matched, but they're pretty good.

11-18-2009, 12:50 AM	#6
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	No point in sticking with stock rods if you're going with premium pistons. Actually, the original rods are more likely to fail than the original pistons would have been. New OEM rods would be fine, but I'd have them balanced and cryo treated... depends on your goals with this engine.

11-18-2009, 01:00 AM	#7
camdiddy Stock Join Date: Jun 2009 Location: Avon, IN Posts: 6	Yea i agree. Here's the situation, I found someone selling a running 7mgte motor w/ r154 (~110,000 miles), t4 turbo kit, extra block bored .040, and extra polished crank all for a decent price. I have a 86.5 7mge auto that I will be swapping this into so I'm just scoping out what all extra I am going to have to buy to build and swap the motor. Right now it looks like im going to need... forged pistons and rods wiring harness/ecu gaskets intercooler driveshaft and whatever else needs replaced on the gte and trans

11-18-2009, 09:24 PM	#10
camdiddy Stock Join Date: Jun 2009 Location: Avon, IN Posts: 6	Thanks for the responses guys. I am shooting for a reliable 350-400 whp car and based on the reading i've been doing, some new oem pistons and rods should be fine for this set up. If i had money in da bank, yea i would definately go for the forged set, but spending a grand on internals isn't in my budget right now unless i can find a good deal. ...so are the original/stock gte pistons forged or cast?