Well the Supra has broken down! Plz Help!!!
 

well it looks like my supra has destroyed at least one piston:( . And I have to get it fixed but I?m thinking does anyone know where I can get Stronger pistons and rods that can easily put up with 24 psi ? and is there something else that i have to strenghten also ? I just want it to handle up to 600 hp or like 500-550 whp

But something cheap because I have to get it Shipped to Iceland And for exampe if something Costs 2000 dollars in America then I have to pay like 4300 dollars when it arrives here becaus of very high taxes and shipping costs

And I?m maybe thinking while I?m doing that maybe I should upgrade to a single turbo becaus I don?t trust the Twins to handle that much boost

I would really be thankful if you would direct me to someone who sells good products but for a fair price :)

:dunno: doesn?t anyone have any suggestions ?

:dunno: doesn?t anyone have any suggestions ?

well this forum isn?t very active :( is there some other forum that is bigger and more people chatting

How did the piston get destroyed? Oem pistons can old 24psi and 550hp easy...even 30psi and 800+rwhp is no problem...but not on pump gas. The most expensive pistons you can get (JUN/Cosworth) won't hold 24psi on pump gas either, because at that boost level & octane you're not burning the fuel, you're DETONATING it. If it's only the piston that's destroyed, put a new oem piston in there (Toyota should quote you a fair price), run race fuel, and you're done.

P.S. I hope your cylinder wall isn't damaged too...

yes I was on pump gas but this car has always been driven on pump gas it?s a daily driven car.
How much Octane do I need to be safe ? here in Iceland you can buy 98 and 99 octane gas at pumps I think in you standard that would be 94-95 octane

How long can the stock pistons handle 20 psi? how many miles?

Unfortunately, I can't give you that answer unless you first tell me your maximum boost level. In theory, if you want to be totally safe for all boost levels no matter what, and you're on an unlimited budget, you could simply run pure VP-Import 120 octane fuel. Of course, that'll probably cost you $20/gallon (USD) or so. For the rest of us that don't have $$$ to waste, the full-time VP-import option really isn't practical. To determine the most cost-effective option, you first need to determine the maximum boost level that you plan to run (eg. 20psi? 24psi?)...and from that figure...(and the ignition timing curve in the ecu that you're running (I assume it's a bone-stock oem ecu))...you can then determine the approximate minimum motor octane level you need in the your fuel to be 'safe'. After you have that minimum motor octane number, you have to determine where you can get race fuel locally, and what brands/octanes are available, for what prices.

For 20psi (or possibly a little more), I'd guess that pure 100 (motor) octane fuel would be sufficient. This is but one option, and not necessarily the most cost-effective option in your area. For example, it might be more cost-effective to purchase c16 leaded race fuel and mix it about 1:3 with pump gas (i.e. 34% c16 and 66% 'premium' pump gas). You can also consider using Toluene (instead of c16) at approximately the same ratio, if that's easier for you to obtain. Yet another way to supplement your octane level is methanol/water injection.

Another fact you might also find interesting is that you don't have to guess at any of this boost vs. octane stuff, or even take my word for it. If you monitor your ecu's knock and timing retard function, you will see yourself when your engine starts detonating with your chosen boost+fuel combination...and then you can react by (immediately) reducing your boost, or by increasing your fuel's 'net' motor octane level. For example, on a US-spec '93-'95 Mkiv Supra turbo, you can monitor your oem ecu's knock function and your oem ecu's timing with a device called a Techtom MDM-100. For US-spec '96-'98 Mkiv Supra turbos, this OBDII Scan Tool works well.

Do you mean 20psi on pump gas, or with race fuel?

If you're asking about 20psi on pump gas, when your engine starts detonating, NO brand/model of piston can handle it. In other words, (again) detonation will damage ANY piston. It will also damage your spark plugs and the metal in your (aluminum) 2jz-gte head. Fwiw, I've personally seen missing chunks of metal from the inside of a 2jz-gte combustion chamber.

If you're asking about 20psi with enough octane to match that boost level, then the stock pistons can handle 20psi for many, many thousands of miles of 'spirited' driving.

well what about 18 psi on pump gas? is that ok? the Gas that you can get here from pumps is 95 oct, 98 oct and Shell V-Power 99 octane

compared to America 99 octane here is like 95 octane in the Usa

I think you use PON(Pump Octane Number)
And we use RON(Research Octane Number)

So would it be ok to Use 93-94 octane(PON) at 18 psi ?

The short answer to your question is no. For more detail, read on:

Ime, both RON and PON are useless figures. The only number that matters when you're taking about preventing detonation in a turbocharged engine is MON.

According to these links (and others):
http://www.btinternet.com/~madmole/R...RONMONPON.html
http://www.zeltex.com/eval.html
...the MON of what's referred to as 'premium' '93 octane pump gas' in the US is approximately 88. Ime on 88 MON 'premium' "pump" gas, you can boost to about 14psi without the Mkiv Supra Turbo's oem (unmodified) ecu detecting knock and retarding timing. 15psi is boarderline; at 16psi knock is clearly detectable and timing retard starts to occur. Every time you boost over 16psi (without some form of effective octane suppliment, as listed in my previous post), you risk engine damage.

I?m trying to get a hold on one of the previous owner because I know now that there is a another ECU in the car it?s not Stock. Much more gas flow. But I don?t know what kind.
But one thing is weird this car has always been over 20 psi with no problems but maybe 26 psi was just to much. I?m trying to get more information about what exactly has been done.