Stock internals - how much can they take

Q&A regarding engines, turbos, and intercoolers and power upgrades

Postby RedCelicaTRD » Fri Oct 22, 2004 9:21 pm

The 22psi was on a 46trim ct26 so it wasnt really moving massive amounts of air but more then people say the stock HG should handle. Lets just say i was in the boost long enough to get the egt up to the point where it cooked a valve and half a piston is gone.
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Postby ChrisD » Fri Oct 22, 2004 11:00 pm

Zeus wrote:no worries man... i THINK its chris D that mentioned he had some issues with the primer... but then again i could be wrong too :D


Ahh yeah that was me. I think someone wanted me to explain why...I forgot to reply to that but I'll do that here.

Don't get me wrong, it is an excellent write up and very useful indeed.

I guess I'll just go through and pick at the things I have a slightly different opinion of. :)

I'll start off with comments on the SAFC + FPR trick. It says that it should be used in the 230-275whp range. Although it is a great idea in theory, I dont think it is too effective in reality. I lurk a lot on the mr2 board, and have found that a lot of people that have tried this seem to find that they can not make their car run any richer at a certain point with the SAFC. Why? This is because of the AFM. Basically, the AFM is already signalling to the ECU to inject the max amt of fuel that it allows. Adding fuel with the SAFC will therefore do nothing. That leaves you with the FPR, which can be used to add fuel. This is fine and will allow you to sort of crudely tune, but it isn't exactly all that efficient since you can only play with the base setting. The other thing you are left with is to reduce the amount of fuel with the SAFC and increase the base pressure, however the primer explicity says not to do this.

So what do you do. Several people have used the SAFC and FPR to get good results on larger than stock injectors. What do they do? Use the SAFC to make small changes. Get your FP in the ball park for A/F, and then make small changes with the SAFC. This will result in small changes in your timing maps. Since you are having this done by a skilled tuner, they should be able to watch for detonation for you.

Some other people do this with 540cc/min injectors. One member is over 300whp, and basically does this however doesn't make any changes to the SAFC over 4000rpm. Theres a few problems with that too of course. Detonation is more likely to happen at lower RPMs with high load. So 3-4000rpm you might be getting a little dangerous.

What do I think you should do? Well... I wouldn't waste money on an SAFC, myself. Hell I'm at 250whp with no SAFC at all. Crude tuning yes, and overly rich. But a 13.6 1/4 mile time doesnt lie.

However, to go any further, this is my plan.

With the used parts market the way it is, you can find almost complete greddy Emanage systems for the same price as a SAFC. Seriously. The emanage is way more adjustable than the SAFC, plus you get TIMING control! Now you can control your bigger injectors, or your stock injectors just fine. I still recommend it be tuned by someone who is qualified *very important*. This person must be willing to tune so you have zero detonation. I am not a skilled tuner, so I have a J&S Safeguard who will act as my ears when I do this. Although this is expensive, it is a great addition to almost any car IMHO. It's great to have timing control on even your EMS system, however, being able to watch for detonation in real time ALL the time is really really really nice. If using the J&S, you need to have it calibrated before doing this tuning.

Okay, so this is what you need to do. You will still need the FPR and the Emanage now, instead of the SAFC. Dyno is highly recommended, or some way of hearing for knock. Just like any tuning session.

Since emanage will allow you to datalog injector duty cycle, you will want to aim for somewhere in the range of 80-85% max. That is generally accepted as safe by most in the industry. The stock ECU will put you much higher, which is why this can also be useful on the stock injectors.

However, since you are REDUCING the load input to the ECU, the ECU will advance timing. Dangerous unless you can retard it somehow. This is where the emanage comes in. You will now need to retard the timing according to these guidelines to start with, and then play with them accordingly as you hear detonation.

I recommend you retard timing further than how much the stock ECU advances it. Why? Because the stock ECU runs extremely rich, which allows it more timing advance. You will be tuning for a much leaner A/F than the stock ECU uses, although it will still be safe. Shoot for 11.5:1. (I wont get into the discussions on the capabilities of the stock fuel rail at this time...this post is getting long as it is! lol)

on a USDM ECU:

-Reduce load by 20% ---> timing is advanced by as much as 10 degrees at peak VE; therefore retard timing by 10-12 degrees

-Reduce load by 10% ---> timing advanced by 2-3 degrees; therefore retard timing by 3-5 degrees

Notes on the JDM ECU:

-under boost, JDM ECU sees 1-7 degrees more timing advance. Be extra careful here. Retard timing if detonation is present.

-in areas of high VE (low rpm + high boost) timing is advanced <4 degrees

-in areas past peak VE timing is advanced by <7 degrees

-JDM ECU dumps MORE fuel than USDM ECU, but further advanced timing burns it better, and doesnt show up as extra-rich on A/F

Instrumentation is very important as well. If you see very high EGT's you may be retarding the timing too much. Do not continue to boost if you see EGT's skyrocketing.

Always keep in mind that your fuel pressure may need to be changed in order for you to reach that 80-85% DC.

Now, I'm not just pulling these numbers out of thin air. I have used Aaron Bunch's findings from his work with his techtom software. He has played with an SAFC on a dyno and found these numbers out by monitoring the timing maps as changes were made to the SAFC. RickyB was actually the person who pointed out to me that extra timing would need to be pulled because of the change in A/F that we were tuning to.

Since the stock fuel system can be pushed to 275rwhp, you definitely don't need or want bigger injectors or pumps before then.


That's kind of misleading in my opinion. To achieve that much power on the stock injectors you need to be running very high injector duty cycles, which isn't all that safe. Although the stock pump can make that kind of power, I wouldn't say it is a bad idea to upgrade your 15+ year old stock fuel pump well before this point.

You do not need to get rid of the AFM, the TVIS, the EGR or upgrade your stock cams, or port your head, or get a larger throttle body, or an aftermarket intake manifold, or get forged pistons or anything like that until you go over 275rwhp (and way beyond that for some of these things). Don't waste your money on these.


I agree and disagree with this one. To put it one way, no you don't need these things to make 275whp. However, some of these things will allow you to run a lower boost level to produce the same amount of power, which of course, will be much safer from a standpoint of detonation. Cams and intake manifold are good examples. With people showing dyno plots of 250whp cars gaining 30, 40, or even 50 whp with an intake manifold, that would allow you to run much less boost than without. I know many people with cams at the 275whp level. Why do this? Maybe they are on a CT26 still, and didn't want to upgrade the turbo quite yet. One other little thing is that it has been shown beneficial to slightly alter the TVIS activation point. Not necessary, but not a bad mod at all. I think other things like water injection that help to suppress detonation, are not given a high enough importance in the primer.

I agree with the comment related to the AFM, EGR, porting of the head, throttle body, and pistons. No need to touch those.

Alright, after all that, I hope it made sense to some people. I think that the power primer is an excellent resource, however some of the things could be improved in it. I think there are a few better ways that one could make power and keep safe, and even extend the power limits of the stock ECU.

:)
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Postby Zeus » Sat Oct 23, 2004 4:55 pm

excellent write up

I think you summed up my distaste for the safc as well

but i am curious as to how effectively the knockgaurd could alter the timming advance effects... i think that would be a bad solution to a poor tunning set up becuase the knockgarud needs to hear knock before its going to retard anytiming... but it could be an extremely ghetto wayt o get some power...

personally if your not gonna go ems.. atleast get something that can adjust timing as well as fuel

hell with the megasquirt diy fuel computer being so cheap AND it gets rid of the afm im suprised more people arent going that route
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Postby ChrisD » Sun Oct 24, 2004 1:38 am

Zeus wrote:excellent write up

I think you summed up my distaste for the safc as well

but i am curious as to how effectively the knockgaurd could alter the timming advance effects... i think that would be a bad solution to a poor tunning set up becuase the knockgarud needs to hear knock before its going to retard anytiming... but it could be an extremely ghetto wayt o get some power...

personally if your not gonna go ems.. atleast get something that can adjust timing as well as fuel

hell with the megasquirt diy fuel computer being so cheap AND it gets rid of the afm im suprised more people arent going that route


Thanks Blake. :) I totally agree, I wouldn't want to use J&S to cover up a crappy tune. In all honesty you would probably find it really jumpy and hesitant if it was constantly responding to lots of detonation.

I am saying though that it is possible use it to help you do a proper tune, with something as simple as an Emanage, or even as advanced as some of the better EMS's that exist. Takes a lot of guess work out of doing an Emanage tune that I am planning on doing.

Not sure if you have played with your J&S yet, but it is extremely useful for tuning...after spending some time with it, watching how the car reacts to its sensitivity, and watching the EGT gauge, you get a really good idea of how it responds.

If you started to detonate, you would know it. Fast. You'd have time to get your foot off the throttle.

One thing I did notice from a pic of Pat C's interior, is that even he has a J&S system set up!
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Postby Kyoto » Sun Oct 24, 2004 7:07 am

Very interesting guys. Keep it coming! :)

PS: Apart from anything else the Profec E01 module has more bling factor than the SAFC! :lol:
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Postby Zeus » Sun Oct 24, 2004 5:06 pm

chris_dittrick wrote:Thanks Blake. :) I totally agree, I wouldn't want to use J&S to cover up a crappy tune. In all honesty you would probably find it really jumpy and hesitant if it was constantly responding to lots of detonation.

I am saying though that it is possible use it to help you do a proper tune, with something as simple as an Emanage, or even as advanced as some of the better EMS's that exist. Takes a lot of guess work out of doing an Emanage tune that I am planning on doing.

Not sure if you have played with your J&S yet, but it is extremely useful for tuning...after spending some time with it, watching how the car reacts to its sensitivity, and watching the EGT gauge, you get a really good idea of how it responds.

If you started to detonate, you would know it. Fast. You'd have time to get your foot off the throttle.

One thing I did notice from a pic of Pat C's interior, is that even he has a J&S system set up!


Yeah im very interested to see how it all reacts... im waiting to see if it will even work though.. i have heard rumors that the autronic doesnt like the knockgaurd but i cant understand why

and yeah Pat is running one with his haltec set up :)
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