Safe PSI rating on Engine Internals

[spainobain1234]

Hello,
I have a 7mgte 1987 Toyota supra (stock engine internal components) pushing 12 psi with stock everything. This is my daily driver, and the only information I have on the car is a pile of reciepts, basically stating the goods which are a performance shortblock, and overhauled CT-26 (stock 7mgte turbo).

Safely, as a daily driver, I am pushing 12 PSI with a shimmed wastegate (trick to turn up the boost using washers in between the wastegate and turbo). I am using 20w-50 synthetic oil for protection. Is this a safe rating, should I immediately upgrade the injectors, Afm to a Lexus Afm, and k&N, and Apexi Safc fuel management system? Or will that require a tune at the shop. Basically, I want to get everything necessary before taking the car to a tuning shop. What all should I invest in for the future starting at the time of this post?

I am asking for a specific answer to the question; What is the reliable Psi rating on stock 7mgte internals.
Thank you ahead of time.

Respectfully.
Ben

 

[GrimJack]

This is an extremely difficult question to answer. The easy answer is somewhere between stock and 700 rwhp, which is the record for stock internals last I heard. Obviously, the high end of that is very difficult to achieve, and the low end is very easy.

A more sensible conversation would be stating what kind of power levels you would like, what you use the car for, and whether you have a budget you need to stay within. Then we can actually provide advice that's relevant to your goals.

 

[Turbo Habanero]

Like stated above it's hard to answer.

But a couple things i can point out is the stock CT-26 turbo is only good until 15psi and the most power i've heard it making is around 300whp

Also i would not push 12psi with stock exhaust/intake Ect..

you will definitely want to get bigger injectors to make more power instead of the Lexus AFM you might want to start looking at VPC's or the MAFT Pro maybe even standalone to make huge power.

But as said before the record on a stock block is 700+ H.P but every block is different

Now to be specific to this question "What is the reliable Psi rating on stock 7mgte internals" depends on size of your turbo and type of fuel/amount of fuel and tuning and condition of YOUR block.

Also don't forget about Head work and Air Flow

 

[IwantMKIII]

First, there is nothing safe about 20w-50 oil in a 7m-gte. Go back to stock then do some reading in the oil section.

Two, you're asking an impossible question to answer. I'm going to assume you meant "what's the most PSI a stock 7m can take with a stock ct26 without upgrading anything". In that case, no more than 13 in my book. Much above that and one of two things are going to happen. One, fuel cut. Two, the stock ct isn't very efficient much past that range and youll end up just blowing some really hot compressed air and risk detonation. There are plenty of ways to get more power out of the ct26 without upping boost. I wouldn't be concerned with running lean at higher psi on the stock ct. In most cases I've run into while tuning, the stock ecu runs very rich.

 

[suprarx7nut]

20-50 oil? Yeah, change that immediately. The only reason that would be a good choice is if the motor was strictly used for racing or if its on the verge of bearing failure and you're trying to limp it home.

0-30 would be a better choice on a 7m.

For power, you're perfectly safe where you are. The internals won't be a problem for another few hundred hp. You'll run into many other limitations before internals need upgrading.

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[Shifty]

The most important thing to understand is that boost pressure means nothing. You are best to consider maximum horsepower, which in the case of a 7M is somewhere around the 600hp mark, give or take.

In any case, you won't get anywhere near that on your standard turbo so just get a 3" exhaust from the turbo back and a big 'cooler. This will transform the car, be relatively inexpensive, and not challenge anything at all (assuming the engine is in good condition and the head gasket issue addressed). Remember to remove the shims as these mods will increase boost levels automatically so take that back to stock and have your tuner put it on the dyno to check it is safe.

You may need a fuel cut defender to stop cut on small spikes but your tuner should be able to organise this.

 

[Supracentral]

You may need a fuel cut defender to stop cut on small spikes but your tuner should be able to organise this.

A fuel cut defender is a way to mask that your tuner has given you an overly aggressive or bad tune, or a tune that is beyond the capability of the current engine management, it's a recipe for disaster:

http://www.supramania.com/forums/sh...ender-Problems&p=941048&viewfull=1#post941048

It's a signal clamp. Which means that once you've gone off the end of the fuel map, an FCD will just lie to the ECU and not report increased airflow that is off the end of the map. So the ECU runs the amount of fuel for airflow the FCD is reporting and not the actual air flow.

FCD's are very a bad idea, especially when the OP's request is specificaly about how he wants a reliable daily driver.

 

[Shifty]

A fuel cut defender is a way to mask that your tuner has given you an overly aggressive or bad tune, or a tune that is beyond the capability of the current engine management, it's a recipe for disaster:

http://www.supramania.com/forums/sh...ender-Problems&p=941048&viewfull=1#post941048

It's a signal clamp. Which means that once you've gone off the end of the fuel map, an FCD will just lie to the ECU and not report increased airflow that is off the end of the map. So the ECU runs the amount of fuel for airflow the FCD is reporting and not the actual air flow.

FCD's are very a bad idea, especially when the OP's request is specificaly about how he wants a reliable daily driver.

I understand entirely what a FCD is. Unlike 98% of people on automotive forums, I am not in the habit of giving advice on things I do not understand.

I recommended that the OP upgrade intake cooling and exhaust, but to remove the wastegate shimming already in place as the modifications I suggested would in themselves cause a boost increase.
I advised that the OP should then have a dyno operator check the car out for appropriate fuel mapping / AFRs.
It should be completely fine, but there is a small chance that with a particularly efficient exhaust and intercooler it could occasionally graze the fuel cut.
Hence my suggestion that an FCD may be needed if the tune has been proven safe by professional dyno analysis, but it occasionally touches boost cut due to inherent efficiencies in the setup.
It was not my recommendation to crank the hell out of the boost and use an FCD in order to show how much smarter you are than Toyota's engineers.
An FCD is not a tuning tool, and this is where the 'problem' comes from as most people use them as such.
An FCD is something used to protect against a rather vicious/annoying occurrence due to a technicality that is irrelevant, if you have had your tune checked out on the dyno and it is safe.

If you think that's bad advice then I'll stop posting...

In honesty, my recommendation is to go straight to a standalone (and you will see that from another post I made only a few hours ago in another thread) but most people aren't interested and won't do it no matter how many times you tell them to (yourself being a case in point, persisting with apexisardavfclexusafm type rubbish that 'works' but in many cases is still a compromise and better performance could be had with less complexity and better control. Carbies work with turbos too, but you won't see me putting one on my car!

 

[Supracentral]

If you think that's bad advice then I'll stop posting...

It's called a difference of opinion, (I am allowed to disagree with you) unwad your panties and get over it.

I stand by my statement that an FCD is never necessary. If you require one, you're beyond the capabilities of your current engine management. Your opinion may vary, and that's why this is a discussion. If I wanted to talk over you, I'd put up a blog and disable comments...

 

[IndigoMKII]

I personally would NEVER use an FCD, fuel cut is there for a reason. It's to protect your engine from possible damage, if you have little spikes that are causing FC then lower the boost a tad bit. Why risk the engine to keep the annoyance out of it when you can simply just drop a psi or two.

 

[Supracentral]

I personally would NEVER use an FCD, fuel cut is there for a reason. It's to protect your engine from possible damage, if you have little spikes that are causing FC then lower the boost a tad bit. Why risk the engine to keep the annoyance out of it when you can simply just drop a psi or two.

That's where I'm coming from. FC is your ECU's way of telling you you're pushing it too far.

As I've stated elsewhere, fuel cut is like a rev limiter. Completely removing it is, in my opinion, a fools errand.

 

[Shifty]

If nothing else, at least avoiding FCDs is a positive change to the traditional US reliance on piggybacks.

 

[Supracentral]

If nothing else, at least avoiding FCDs is a positive change to the traditional US reliance on piggybacks.

Exactly. An FCD is a band-aid. If you need think you need one, you've got bigger problems. 20 years ago, there were few choices and even less knowledge about how these systems worked. Today, there's no excuse for it.

 

[Raven97990]

The hks fcon fully controls the injectors on its own map sensor and fuel tables- a fcd to stop the ecu from fuel cut is required but it works only when there is a piggy back controlling injectors independent of factory ecu

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[Supracentral]

The hks fcon fully controls the injectors on its own map sensor and fuel tables- a fcd to stop the ecu from fuel cut is required but it works only when there is a piggy back controlling injectors independent of factory ecu

Good caveat. But then again, the F-Con for the MKIII also belongs in a museum.

 

[Raven97990]

Good caveat. But then again, the F-Con for the MKIII also belongs in a museum.

I live my fcon and its massive fireballs! If you recall at Jeremy's first shootout the power and torque it managed. I would leave the fconn to stock Turbo or small Turbo upgrades.

Doesn't the greddy emanage also drive injectors independent of the ecu?

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