Why does the Corolla XRS beat the tC?

[navylife59]

Isn't that supposed to be 7PSI? Sounds like you made a good friend.

[Jay666]

Oops, I meant 7, not 4. Sorry.

They wanted to push it to 8. No way, not without a re-build.

[navylife59]

Well, shoot. I am running 15PSI, no type of intercooling whatsoever, and just the ECM with the TRD reflash. Car is running smooth with lots of power. http://www.club-tc.com/forums/member...ect-tc-15.html

[Jay666]

Huh. Well, he did say that it's not that it CAN'T be done, it's just that there is a certain level of risk involved in blowing a gasket and such, unless the engine bottom end is re-built. Both he and the guys doing the dyno said they COULD tune the car at higher than stock PSI, but there's risk involved. They told me it may be fine, it may not be fine, it may be fine for a while and then something may suddenly happen... it's all about how much risk I wanted to take. I told them "no thanks" and kept the car at standard PSI for now.

Does that not seem right to you?

Also, how did that work with the TRD re-flash for you tuning to higher PSI? Because what they also told me was the re-flash will tell the ECU to run at stock PSI becuase the re-flash is a Toyota pre-determined setting and that if I DID want to tune to higher PSI, they would have to do something else with the re-flash. (tune it without the re-flash I think??? Or modify it somehow??? Can't remeber the details on that.)

[navylife59]

Taking the safer route is always a good choice when it comes to your daily driver. There is truth in what you are being told, but all is not quite what it seems. You have no doubtingly heard the adage of "Boost is boost". In essence , boost is boost but there is a difference. That difference is in how the boost is made. Run a turbo like I am doing @15PSI and there will definitely be an engine failure in the cards. So how come I can run 15PSI, no intercooling, on the stock ECM with TRD map, and no built motor? Easy to explain.

After a turbo is spooled up, what ever boost level that is set, comes on all at once no matter the engine RPM (within the powerband). There is a stark and drastic difference in the cylinder pressures. This causes stress fractures and blown gaskets. Of course, a progressive boost controller would help to alleviate the situation. Engine EGT's are much greater on a turbo, as such, there is a high level of heat transference between the turbine and the compressor sections. Lastly, turbo kits either come with a piggyback or not. What they do not have is the TRD maps. Running a turbo on just the stock ECM is bad news and a catastrophic failure waiting to happen.

A S/C is belt driven so it is completely dependent on engine RPM. Maximum boost only comes at WOT at engine redline. So slamming the gas at 4K RPM is only going to net about 7PSI that will slowly build to 15PSI at redline. The pressure that is compressed into the cylinders builds up in a linear fashion, slowly. The stresses induced are more aptly absorbed by the metal structures. Compressing any gas will generate heat. This is true of all S/C and turbos. A S/C, however, is not coupled with a turbine. Thusly, it does not have the detriment of waste heat generated at the turbine. The secondary effect of increased underhood temps is also reduced. My engine also is running 550cc injectors over the TRD supplied 440cc units. The ECM does not know this so at WOT throttle, it is injecting more fuel than it realizes making the engine run rich. The extra fuel provides a cooling effect to the piston head. The ECM also has the benefit of the TRD maps. Unlike maps on a piggyback controller, the TRD maps operate more than just at WOT being across the entire spectrum of engine tuning. The ECM is also a learning computer and with the instructions of the TRD maps, knows that it is flowing more air with increased cylinder pressures. When A/FR's get out of hand and knock occurs, the ECM pulls back timing. There will be a point that the engine will not be able to prevent a lean out, such as with low octane or excessive IAT's. I have till next Summer to worry about it.

As I stated above, the TRD reflash has much more to it than just altered ignition and WOT settings. Toyota had to keep the engine 50 State legal, fuel economy up, while not affecting engine longevity or driveability. It is also encrypted requiring a special interface tool to upload. It is near impossible to either alter or upload a different set of maps to the ECM.

Am I playing with fire? The answer is yes. I was a Boy Scout and still have my Fireman Chit so I should be OK.

[Jay666]

Some of that I actually understand. Not all of it, but some of it LOL.

So, if I want to eventually have the top and bottom end engine re-built, I STILL should run the TRD re-flash?

If so, I'm not sure how the hell that works because the factory settings on the re-flash (specifically the PSI) will be set much lower at stock levels. How can you tune the car to run much higher with the re-flash?

Please explain how that works because I eventually plan on having a full engine re-build. And I'm not understanding if or if I will not need to have the re-flash as the way it was explained to me by my tuner was that I can't run the re-flash if I want it tuned to a higher PSI.

[navylife59]

The mystery will be revealed once you understand one key factor; the ECM has absolutely no idea what PSI the manifold is pressurized to. There is no MAP sensor. What the TRD maps do is allow the ECM to keep the motor stoichiometric without running into dangerous levels of knock. These were determined on extensive engine dyno testing. Using various algorithms, throttle position, IAT, and MAF sensor input; the ECM determines engine load. Dyno sessions return data on how much increased airflow (read by the MAF in grams/sec) per engine speed over the N/A motor. This data, along with the engine load values, set fuel and ignition schemas. Increasing the manifold pressure requires more fuel to lower EGTs and chances of knock. This is why increasing injector size and available fuel rail pressure in critical when you are limited in altering fuel/ignition control, such as, with the 2AZ-FE ECM. The TRD reflash is the essential component to make this work. Without it, the ECM would not be capable of managing the A/FR overly flooding the engine.

[Jay666]

I feel like I need a degree from MIT to comprehend most of that.

So, I think what you're saying that if I choose to re-build the top and bottom end and have the car tuned to a much higher PSI, I still can (and according to you, and for that matter Kenny Tran), I SHOULD perform the ECU re-flash?

[navylife59]

Yes. The TRD Reflash should be done 100% of the time for all S/C motors. It is highly recommended for turbo apps too as it puts the ECM in a better mood for F/I.

Sorry about all the technical lingo. I assure you that I am not trying to talk over everyone's heads. Surely my head is not that big. I think. I put it in the technical terms that the topic demands in hopes that Members can pick up on the jargon and have more breadth of understanding the principles and true reasons of how things work. There is so much BS out there it is sickening. Only a true Texan is authorized to feed you a line of BS. Just looking out for my birth right.

Seriously, the best way to learn technical and complicated information is by immersing yourself in it and asking lots of questions. I also try to keep the abbreviated terms to a minimum, except for established ones. I learned all about hotrodding and building motors by hanging out with the older kids helping work on their cars. I questioned every step of the way. The bits of information that I received was easy to figure out betwixt BS and the real deal because I was putting action to words. Quickly did I discover what worked and what didn't.

[Jay666]

Sorry, I didn't mean to make it sounds like I was offended by the fact that it was so complicated. I was more commenting on my own shortcomings of being able to understand some technical discussion that is over my head.

I always appreciate your help. In fact, I wish I could pick your brain in person LOL. Or have someone like you at my disposal on a daily basis close to home.

I will make mental note of the fact that the TRD re-flash must be done 100% of the time. But I may need your help again in the distant future reverting that information and exactly why to the guy I go to now in order to avoid any future catastophies when I eventually have the engine re-built and switch to turbo & etc.

If that's okay with you of course. Knowing this helps, but it's even better if I can explain to him WHY and where I have learned this so things are done properly. I have come across so many different answers and opinions on how or what should be done in this circumstance, I want to make sure it is done correctly and I understand exactly why.