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The mkiv Supra Owners Club

Stock internals limits


gavin.starr

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I've done a search and nothing conclusive turned up.

 

I have recently purchased the HKS to4z turbo kit from the for sale section. My question is,(I know this has been asked a thousand times) what are the safe limits for the stock rods and pistons?

My engine is going to be rebuilt in the near future by Paul and his team due to my (suspected) bottom end bearing damage. I was thinking of asking to get brian crower sportsman rods and CP pistons installed to future proof the engine if i fancy some more poke later on down the line.

 

But are they really needed? I estimate it to be completed in the region of around 600 bhp give or take, I obviously have a budget and im trying to keep it as low as possible.

 

Any help would be great.

 

Gav

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To4z should be fine on stock internals, if you're looking for 600-700hp.

 

the longevity will be decided by the health of your engine, the condition/ quality of components used in the build, being put together by someone who knows what they're doing, and probably most importantly, whoever sets up and maps the car.

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Someone on facebook today posted stock NA-t engine bar lowered comp and eagle rods, 799whp. Looked the part with the dyno vid's.

 

Pulley bent his conrod at 750whp on his stock NA bottom end too, so would back up it's the rod that's weak.

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264 cams are on the build list to help with the breathing, Im leaning more towards getting rods and pistons installed now just for peace of mind. Its just another 1k on the shopping list :rolleyes:

 

Over the years it seems that people have had more problems after cracking open a motor to install different rods and pistons than those who stick to a stock block and run around 600bhp with a decent tune...

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Guest Patrick94TT

In the States we have made 1000hp on the stock block but yes you are on limited time with the rods at that point. This was on a ProEFI computer.

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I know people have done 1000bhp on stock engines, but I honestly can't see that lasting 2 min unless the car is just a dyno queen or comes out of the garage once a year for a quick highway pull.

 

I wouldn't go much over 650-700 and 2 bar boost if you want it reliable. Every time I've pushed a stock engine I've had head lift issues once I go over 2 bar and I'm in the higher gears. I've killed two engines with head lift.

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After *ALL* my years on this forum I have seen a *TINY* number of proper engine dyno verified power and torque figures. In my opinion 500 to maybe 600 flywheel BHP is a sensible figure if the car is used on track (not strip) for extended periods of time. Even then you'll need decent forged pistons, and a LOT of oil cooling. The firts thing you need is a totally fresh base engine, assembled properly, not a 100,000 miler with oil pump wear, tired bearings and worn bores and rings. Then you need to decide at what RPM the power is to be delivered. Over 550 BHP expect engine life when run at the upper end of the power graph to be in the sub 15 hour region between rebuilds. Some of the figures mooted are plain ridiculous if any factor of reliability is expected. Others are just plain ludicrous, full stop ;)

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In my opinion with 600-650hp on street use it will last for a long time, after 700hp you are pushing it.

 

That being said, I had 750-800hp on my car for two summers and the engine kept alive yet another summer on a mates car on similar hp. But I would keep a spare motor with this kind of hp and I was planning to rebuild it once it would explode but it never did :)

 

I also did some standing mile runs and 10 seconds passes on the strip, so it wasnt babied.

 

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Most people would agree that 600-700hp is the limit most people wouldn't pass if you want reliability. As long as you do regular oil changes, services & inspections say every 3000 miles or less, then there's no reason why it shouldn't last.. Anyway most people that have this sort of power tend to pamper there cars to the highest level all the time anyways. :D:D

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I've been running my stock engine on a single setup for almost 15000 mls ; 550 bhp (1.5 bar with 60mm) for around 5000mls, 630 bhp (1.5 bar with 66 mm) for 5000 mls, 700 (1.8 bar with 66mm) for another 5000 mls.

 

When we opened the engine for a rebuilt, it still looked quite fine :)

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At which point it ceases to be a stock engine. :D Like any part of the car, once you fit 'uprated' parts, it isn't stock any more.

 

But to me, I wouldnt class dads engine as a "Built engine" I was wrong when I said stock I agree. Yeah its got ARP bolts and Clevite race bearings. But apart from that its stock. So we will go with semi stock :D

 

I'll just shut up, im still only a young boy :D

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