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Discussion Starter · #1 ·
Does anyone know how much tq/hp the stock engine & drivetrain components have shown to be reliable to? I'm wanting to look into forced induction at some point for my IS350.
 

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In the US anyway the only forced induction option is the LMS supercharger kit, which runs 5 lbs of boost... I doubt that will be much of an issue to the A761E.. you're only adding about 15% power.
 

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i was thinking more along the lines of a custom rear mount or STS. If the rumors are correct and no ECU modification is needed for low boost, i was thinking 7-8psi with an intercooler and possible water/meth injection, putting it a bit over 400hp. If thats a bit too much for the stock "cushion" i'm sure a simple injector swap would solve the problem, which would be perfect since the 350's already have the secondary injectors.
 

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Under heavy load the car only uses the direct injectors, not the port injectors, so swapping in bigger port injectors won't do anything for you when getting on it.

I'm not sure if it's even possible to put bigger direct injectors in the car given the way it's all set up and the fact there's zero aftermarket control of the system available...

Combine with nearly 12:1 compression and... well, there's a reason FI options are extremely limited on the car.

You might come up with something custom that'll work, but I doubt it'd be cheaper than trading the car in for an IS-F that already has over 400 hp.

Only 'cheap' significant power adder for the IS350 I've seen is the guy on the CL forums who is running a 65 shot of nitrous- seems to give pretty solid gains for low cost, but it's rolling dice with a $10,000 engine still under warranty.
 

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Under heavy load the car only uses the direct injectors, not the port injectors, so swapping in bigger port injectors won't do anything for you when getting on it.QUOTE]

Are you sure about this? Not trying to be picky but I remember reading the opposite. I.e. The port injectors were only used at WOT (or High RPM).

In any event, the system is complicated and it is slowing down the performance aftermarket. As a IS250 owner, I think it would be hilarious if the IS250’s became easy to hot-rod while the IS350’s weren’t due to the combination FI system. It would stop some of the 250 hating that goes on.:p

Just my rant.
 

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^ It's pretty common when it comes to Toyota vehicles that have the same model car with different engines. For instance, the 7th gen Toyota Celica GT was more friendly when it came to FI while the Celica GTS was more difficult to work with when it came to FI. Same can be compared to the IS250 and the IS350. It maybe difficult for the IS350 to be brought up into the FI world, but with some time, research, and development, it will eventually get there. So don't give up on the 350 quite yet, some will have something working in the near future.

Is250 may have their shine but don't expect the hating to stop.....
 

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I'm not sure what you mean... the 250 and 350 are -both- impossible to change the ECU on (for US models anyway) and both run high compression... they're equally impossible to do any kind of hi-po forced induction on... and the 250 has -only- direct injection so no easy-to-swap port injectors there either.

And yes, I'm positive the port injectors do nothing at WOT. Here-

2006 Lexus IS350 & IS250 V6 lineup AWD VVT-i - Turbo Magazine
The plot thickens with the IS 350's 2GR-FSE engine, which runs a staged injection system with secondary injectors positioned at the port. However, unlike traditional staged injection where the secondary injectors come online as boost is introduced or high load is realized, this setup runs only the direct injectors at high loads.



Basically the port injectors are only there to improve fuel economy and emissions at light/mid throttle conditions.

At WOT only the high-pressure direct injectors are running.


This means if anyone ever -did- develop an aftermarket engine management system the port injectors could be used to add fuel at WOT quite easily. But no such system exists, and nobody is even working on one AFAIK due to both the encryption of the factory ECU and the incredibly complexity of programming 2 independent sets of injectors on a dual VVT engine- especially given it'd be a relatively small market... even smaller now that people who want more HP can just buy an IS-F
 

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I stand corrected. The article you attached was what I was referring to but I read it a long time ago and got mixed up. Sorry.

You make some good points about the 250/350 and forced induction. I was referring to the fact that the 350 has a more exotic FI and would be more trouble to create a piggy-back module to modify for fuel/air ratio etc... That’s the “incredible complexity” that you noted. This avoids having to change the ECU(s) at all. So I guess that would just make the IS250 complex but not incredible so.

The mechanical CR is high on both engines. This is a fact. But the actual cranking pressure is a combination of the cam timing and mechanical CR. Since the direct injection allows for an overall higher CR, I would not discount a boost power adder just yet. Of course, this applies to both engines.

Then there is even more crazy lessons from the past. What if the 350 heads could be bolted to the 250 block? (doubt it) Sure the bore diameter is different etc… but it is one way to lower the CR. What if the 350 Direct injectors could supply more fuel and be used on the 250 (doubt it), Cams,,,,,,,on and on and on, get my drift?

I have no plans to try anything like this but I am a gear-head so anything is possible.

The encryption that you mention pertains to the CAN communication between the powertrain modules within the vehicle. Basically, every module has an encrypted ID so you can’t swap modules from different cars. Also makes SW mods difficult. Cuts down the chop-shop aftermarket. This is a particular pain as the the injector driver and other modules are separate from the main ECU.

Anyone can buy a fast car but sometimes, that’s not what it’s about IMO. This comment is directed towards the IS-F not the IS350.

Damm - we sure did high-jack this thread. No, I do not know how much power the IS350 drive train can take.
 

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If the S2000 can handle 7psi stock with a 9k redline, our motor "should" also.

Doing all the hardware is a peace of cake for me, it's not knowing what would happen that I am a bit worried about.
 
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