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Discussion Starter #1
If you search through the forum for 6MGTE or 5MGTE, the usual results you get indicate that the owner either lost a piston, damaged a turbo, or blew a head gasket. When new forum members discuss what motor should they use, everyone says that the 5M and 6M just can't stand up to boost.

Does this combination really work?

I'm sure there are people successfully using this combination without problem, but I don't see much about it.

I would assume that the secret to using this combination is fuel management. What have people used with these motors? Years ago, after market add-on systems added additional fuel under boost conditions. Rising Rate Fuel Pressure Regulators (RRFPR) monitored boost levels and changed the EFI fuel pressure to prevent systems leaning out at high load. How well did these solutions work and are they available now?

What is the current solution to fuel management? I have seen a lot of MegaSquirt articles, but how many have been successfully using one to control fuel on a 5M/6MGTE engine?
There have been a lot of variations of the MS system, some of which are no longer available. What combination is the hot setup and how difficult is it to make it work?

I would love to hear from people who have, or are currently running a 5MGTE or 6MGTE and hear their opinions on whether this combination is practical. I realize that newer motors may well be more practical, but these motors just seem like a period correct hot-rod combination.

Dale
 

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Not great. Head gasket design is the same as 7M and the stock cast pistons can’t handle much heat or detonation. With very good fuel management it can work well but most people who have the time and money to install good fuel management will go to a 7MGT or JZ swap instead. Also most 5M/6M engines are getting high in mileage and pretty tired out, and again people doing these builds don’t want to spend the money for a complete rebuild. Generally reliability decreases linearly as boost pressure increases.
 
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Or then there's me who built a 6m-gte in 1999 and literally have not done anything to the engine but ordinary maintenance, not even any re-tuning in over 20 years. At the risk of jinxing myself, it just works.

However the difference between me and the average guy is that I didn't start with a used motor with 150K miles on it. I started with a fresh rebuild, forged pistons, metal headgasket and all the hot-rod machine shop tricks that have been known for decades when building a motor for extreme durability. However, looking back, I think a lot of that was probably overkill.

Another difference is that I never got greedy. I put in a freshly rebuilt ct-26 with the stock wastegate actuator and left it there, seeing between 7 and 8 psi boost on the gauge. I've never shimmed a wastegate or otherwise tried to see what it would do at 14psi. I basically built the motor that I always felt that Toyota should have put in it at the factory. But it cost me. I spent upwards of about $7,000 on the build. I'm sure it'd be $10,000 or more now.

The only issues I've had have been with the aftermarket parts which are inferior in quality to the Toyota parts. I had to r&r the fuel pump a few times because of a bad batch with a manufacturing defect. Got my money back on those. Finally got a Bosch pump that worked. It lasted about ten years and running a genuine Toyota mkiv Supra fuel pump for the last ten years. The Cartech rising rate fuel pressure regulator is hard on pumps tho, spiking to 70-80psi under boost. And I had a diode burn out in the MSD boost referenced timing control system. Had to get a higher rated diode from Radio Shack but was a 50 cent fix. Other than that, I've changed the fluids and belts. That's it. Its been driven cross country once, a couple of long trips and done a couple of seasons of autocross. But mostly it's been back and forth to local car shows which doesn't require obscene HP, just enough to have a little fun between stoplights.

If I were doing it today, I'd probably buy a programmable aftermarket ECU. But back in 1999, that was going to cost $3,000-$4,000 installed compared to about $600-700 for the Cartech and MSD gadgets. I haven't done much research, but it seems that today you could do a proper computer control for not much more than those gadgets cost, plus I'm a little better off than I was back then.
 

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Discussion Starter #5
Im running an HKS F-Con. Old technology but it works. Why change it.
How has the motor held up?
How many miles on it and have you had any reliability issues due to the turbo?
 

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Im running 82-83 low compression pistons stock 5m crank and rods amd a 2mm HG. At 8 psi its held up well. 6K miles since the rebuild and its held up well. Previous set up was 6m Eagle rods and Wiseco pistons. I was having ring issues because i was running a giant oil cooler at the time and the oil was not getting up to proper operating temps for the rings to seat.
 

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Any of these types of projects it comes down to how well it is tuned, the quality of parts used, and the condition of the motor. With a bad tune you can even blow up a 2JZ. If its done well and the goals are modest I would say yes it can be done. The problem you run into is once you build a nice motor and throw all these great parts at it you could have put a stock 2JZ in it and made more power and reliability.
 
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