Engine Parts that Fail on a Supra

[Geo]

When going the Single Route -

 

 

i was asked the question today why i wasn't replacing Pistons and Rods on my build when it was in bits already? my answer was well im not going to be running enough power to warrant it. And that the stock rod/piston combo can take a good amount of power.

 

So here is the Debate im about to open/can of worms

 

Stock Rod/Piston Combo Vs Uprated Combo? im pretty sure or 99% know the way im going with the build, but wanted you guys inputs as to the Pro's and Cons

[tooquicktostop]

Mark at Phoenix had a conversation with me some years ago about how I should approach my build, He suggested you should firstly avoid opening the engine at all if all is well with a leakdown test and replace just the oil pump and water pump and service, however my engine had failed so the next best thing would be a new block from Toyota and then stock pistons with uprated rods as these are a known weak point, finally ARP bolts and new gaskets, no need for uprated bearings or pistons (my goal was around 600BHP)

 

It was once built an engine Mark was willing to guarantee to a modest power level

[Chris Bailey]

I was always under the impression that the stock piston and rods could take big power, I've heard that in the US they make around 1000bhp with the stock combination. But who knows if thats actually true? I personally wouldnt want to push a stock engine much past 700bhp. I know Jamie blew one up at 730bhp. The weak points are the head bolts, main studs, and rod bolts. I assume you are uprating them to ARP bolts?

[bignum]

I was asking myself the exact same question a couple of months back, and my conclusion..

If looking between 600-750 bhp on a sensibly sized turbo then stock internals are fine, although rod bolts and everything balanced would be done,along with head stud kit.

If going for 8/900 with wild cams and turbo then you need to raise the rev limit to make use of that power which is where rods/pistons etc come into play.

[Luxluc]

I was asking myself the exact same question a couple of months back, and my conclusion..

If looking between 600-750 bhp on a sensibly sized turbo then stock internals are fine, although rod bolts and everything balanced would be done,along with head stud kit.

If going for 8/900 with wild cams and turbo then you need to raise the rev limit to make use of that power which is where rods/pistons etc come into play.

 

Perfect answer.

[jazz1]

Me personally I prefer fully built bullet proof engine you never know when you fancy more power .

[j_jza80]

Built engines seem to cause more issues than they solve.

 

Totally stock, unopened engine running 500-600hp is the Supras 'sweet spot' IMO.

[jazz1]

Built engines seem to cause more issues than they solve.

 

Totally stock, unopened engine running 500-600hp is the Supras 'sweet spot' IMO.

 

Depending upon who built them .

[Abz]

What sort of power level are you aiming for Geo?

[Swampy442]

Built engines seem to cause more issues than they solve.

 

Totally stock, unopened engine running 500-600hp is the Supras 'sweet spot' IMO.

 

This.

[Geo]

anywhere between 700-800 i reckon, i really fancy a super fast street car. imo anymore up here in scotland with out roads is just daft, 9/10 its raining up here

[Luxluc]

I was running my Supra at 740 rhhp on stock botton end and head (only 264 cams) Geo.

 

I think you can run that powerlevel as long as the torque and rev limiter remain reasonable. The main reason I went for the built engine was that I didn't want to risk too much. The fact that my Supra revs beyond 8000rpm now is very nice, something that you can only have with forged internals. I can take full advantage of my (little) 67mm turbo.

[johnny g]

I'd be loathed to run those pistons again, especially if you've had the bores cleaned/honed, you'd need some oversized ones, surely?

 

As mentioned above, a stock unopened engine with new pumps and belts should see you to 600bhp without too much issue. However, now that your block is open, I'd look at sending it to CW to build up with some good pistons and rods.

[Chris Wilson]

Utter madness to build an engine with a goal of near triple the power output of a brand new optimized new one using old cast pistons. Block needs reboring and honing to suit each of the new six pistons. If you *MUST* run the block as is, be sure to buy new pistons that allow hand gapping of the rings, as normal wear and the re-honing will have left the basically stock sized bores slightly oversize. Not sure what piston and ring combinations are available in stock size that allow hand gapping... I would rebore and fit decent forged pistons. Personally I think your goals are unrealistic, and if the claims of these power levels are true, which i doubt, the engine will have a lousy torque curve, be stressed to an inch of its life, and be in need of regular rebuilds if used much at its alleged potential. Note how many members have built, or had built, mega HP engines, yet are now running less power for reliability and drivability, or driving GTR's 500 BHP is the sweet spot for a road car. Small single, proper mapping, mild cams, big area under the torque curve.

Edited November 3, 2014 by Chris Wilson (see edit history)

[j_jza80]

anywhere between 700-800 i reckon, i really fancy a super fast street car. imo anymore up here in scotland with out roads is just daft, 9/10 its raining up here

 

For the same money, you could build a quicker car with less power. The extra money you would need to spend on the engine, fuel system, turbo etc over say a 500hp build could be spend on a Giken or TRD diff, Nitron suspension, AP brakes etc.

[Luxluc]

Note how many members have built, or had built, mega HP engines, yet are now running less power for reliability and drivability,

 

I only use one setting on my Supra Chris : high boost.

 

I don't get why people have big power cars and not use their full potential.

 

Mine is running 2 bar on ethanol all the time.

[Mugello]

This is a question i have personally been going over in my mind a lot recently with my build coming along.

 

Personally if you have opened the engine and had it re-honed and straightened it would kill me to put back the stock pistons with new rings and rods. I would upgrade the pistons and rods while its in pieces with ARP bolts throughout + new core plugs. The thought of it failing later on and having to basically do the full job again, for me, is too big a risk and pain in the backside!

 

Of course budget is a big factor to consider which is also pushing me personally to not opening the engine, and as mentioned on page 1, just turn new pumps/belts etc...

Edited November 3, 2014 by Mugello (see edit history)

[Chris Wilson]

So long as they have not seen any serious over revs, or spun rod bearings, the old rods, checked for cracks, size and straightness, should be OK. I have a brand new set of ARP rod bolts if anyone wants them, also a set of crack tested and balanced stock rods, from an N/A auto, that had a lady owner and did low miles. (N/A rods are *EXACTLY* the same as TT ones in JZA80 none VVti N/A's).

[johnny g]

George, going on what you said up top, about always raining wanting a fast road car. Why not build a GTX35R (or equivalent) single and aim for 500-550bhp with monster spool - and properly sorted suspension?

Edited November 3, 2014 by johnny g (see edit history)

[Chris Wilson]

That's the way to do it! The best 2JZ Supras I have driven on the road have had fairly modest power, oodles of torque and full boost by 4000 or so RPM. Decent road suspension, Giken LSD, modest wheel and tyre sizes and they are faster point to point, and MUCH nicer to drive than the mega BHP things on stiff suspension and ginormous tyres.

[johnny g]

That's the way to do it! The best 2JZ Supras I have driven on the road have had fairly modest power, oodles of torque and full boost by 4000 or so RPM. Decent road suspension, Giken LSD, modest wheel and tyre sizes and they are faster point to point, and MUCH nicer to drive than the mega BHP things on stiff suspension and ginormous tyres.

 

That's why my (GTR) is perfect. 630-640bhp/620lbft. 600lb/ft from 3000rpm and it's . Love it.

[Geo]

yeah im loving the sound of properly set up fast spooling road car. it would never be traacked so all those horses wouldnt be used properly. im gona look into see what options i have for increasing spool and getting that power planted.

[Luxluc]

For a power goal of 700-800 bhp, you will need at least a 67mm turbo if you plan to run pump fuel. Ethanol would make the same power on a 64mm turbo with great spool.

[Kaan W]

In only had my Supra with 600 odd hp for a little while before I wanted more. Might aswel build the block with the potential to withstand more when you get bored of that.

[Chris Bailey]

Have to say I do agree with the rest of the guys, we had dads supra mapped the other month and asked Ryan to make it as responsive as he could. As always he didn't disappoint. 570bhp and 640lbft at 3700rpm still on the stock cams. Like you Geo we had the engine totally rebuilt, and added some new uprated parts that are prone to fail, so it has ARP bolts etc and also Clevite race bearings. Apart from that its a fully rebuilt uprated motor. People ask why we didnt build the engine whilst it was apart, But we was new to ownership and at the time we was BPU and didn't plan to go down the single turbo route at all. The only reason it was rebuilt was because of various oil leaks and with parts and labour added up it was only an extra £1000 or so to have the engine fully refreshed. Its been fine ever since and runs like a swiss watch (touches wood)