i always thought centris made boost quick and kept it pretty flat but ive seen a few graphs like you describe, where the boost is a constant upward climb. is that typical of max effort type builds?
the only centri ive had was a zx10 with a miata centri. it made 8psi and held it flat across the rpm range.

 

youre thinking of roots/twin screw style. They make max boost almost instantly and flatline throughout the rpm range. Cebtrifugals are rpm dependent and increase boost all the way to redline unless you run a wastegated setup.

 

As ddn says, centri's generally boost will increase with rpm's, obviously there can be slight variations with different setups, but that is normally the case.

And dont think that because positive pressure may not appear on a gauge at lower rpm's or loads, that the blower isnt providing any air, it absolutely is, and it does help performance even off boost as you might call it.

As for tuning turbo/centri/anything....same process really. They're all just engines.

 

LOL - thanks for opting in to make that decision for everyone. I'd ask for your qualifuckations in doing so - but, don't really care.

 

Here's my graph that shows this. 5.3 with a F1D Procharger. Torque starts leveling but never goes flat.

 

^^^^^^ This makes me want a Procharger even more than I already did.

 

Look man, I call a spade a spade. As for good tuners, getting rid of the MAF (especially in a forced induction combo) has zero to do with his/her ability. Also, there is no need for me to qualify anything. I never claimed to be a good tuner.......I was just saying that the statement you made above was dumb. Unfortunately, you are probably just re-typing **** you read in another thread.....because everything you read on the internet is true.

 

didnt you hear, more than 12psi on pump gas will frag a LS?

 

Wait, it is all true right?

I claim to have zero tuning knowledge but my understanding has always been that a MAF system responds better to modifications and atmospheric conditions. By better I mean it compensates for changes automatically, to some degree. Is SD going to be right if I have my car tuned during the summer in Florida and then drive up into the mountains in Colorado during winter?

Again, I'm a tuning noob.

 

That is one hell of an assumption you are making here.

Here (http://www.tbssowners.com/forums/3059162-post744.html) is a perfect example of a well known "financially compensated tuner" failing to deliver for his client, and I stepped in and fixed "their tune". Utter garbage was the only thing the file contained.

I've had numerous other people send me paid for tunes for advice on how to fix their respective issues as sourced from vendors. I don't take money for it and I don't do it for the accolades, I do it to help keep the hobby open source - people helping people. That and I like learning from other peoples' mistakes.

Anyone who chooses not to tune their own car and educate themselves in the process is opening themselves up to accepting the level of effort someone else is willing to make for money on their behalf.

 

Nothing does anything automatically.

It can only do what the tuner has told it to do......or not do.

 

Yes, an SD tune can work perfectly in every condition if done right. The misconception about the MAF comes from the fact that SD does not directly measure airflow like a MAF. This means that the MAF "maybe" will compensate for hardware changes that SD will not. If your hardware remains the same, the tune doesn't change. Also, an SD tune can be done "quick and dirty" for only one specific condition, which may make such a half-assed tune unworkable in a different environment. Hell, even a reasonably well done Alpha-N tune will work in most conditions, and that is scraping the bottom of the barrel of EFI.

 

I'm all about consistency. That means that when I "tune" an ecu, the computer better do exactly what I tell it to. Leaving functions in there for it to "self compensate" can lead you to chasing your tale. Is there a time and a place for a MAF? Sure there is, but it is not on a hot rod especially if it is getting air forced down its throat and maxing out 3000 rpm before you reach red line.

This is exactly why you see most guys who race their cars a lot getting rid of the MAF, the knock sensors and the factory O2 sensors. If the person tuning the car knows what he is doing, those things do nothing to help the car perform better? By turning off the MAF, Knock and Factory O2's, the ecu no longer has the ability to "trump" any changes you have made. This is how you get consistency. Beware though, getting rid of the MAF, Knock sensors and the factory O2's with the wrong person behind the keyboard will likely result in burned up ****.....actually it doesn't really matter if that stuff is still there or isn't, the wrong person can still burn it down.

For those asking about tuning in SD and worried about seasonal changes in the air......it typically isn't much of a big deal. I've got several SD cars that have been on the road for years, year around, without changes and the car runs good in all conditions. Don't misinterpret what I'm saying though.....I said it runs good in all conditions.......it does not run its best in the summer heat and then run its best on new years eve without making some mild changes.

When people ask me about it being a pain in the *** I tell them, you're gonna spend a gazillion dollars on your power plant/FI set up......if you'd like the tune up tweaked a couple times a year.....it shouldn't be a big deal.

OPEN LOOP SPEED DENSITY TUNES FOR LIFE!

 

the factory knock sensors havent been too useful for me. my evo's work great but my truck just seems to detect exhaust pipes clunking around and nothing else. I rattled my #7 apart recently with no sign of knock in the log.

 

That's just as ignorant a statement as supposedly mOtOrHeAd MiKe's comment. Glad you made the statement that you don't claim to be an amazing tuner.

 

Problem is conditions and engines aren’t consistent. A MAF *if setup properly* will help you be more consistent at the track as well as on the street. If you are using a MAF that is maxing out at 3k you aren’t using it correctly. It’s about as useless as a 1 bar MAP sensor at 30lbs of boost. Any sensor used improperly is crap.

Assuming you had the proper MAF for the application and are competent enough to tune with it, what possible reason is there not to run one? It’s an additional data point for the engine. There’s never a instance where more engine data is a bad thing IMO.

Speed density is less complicated and easier. IMO that’s why it is commonly used in aftermarket hotrod applications. Seeing an accurate representation of the air ingested into the engine is great data… esp for a turbo engine. If I knew enough about calibrating and setting up a MAF on my turbo LS I’d run one. Even if I just used it for a gauge and didn’t implement it into the tune, it would be awesome info for trouble shooting and performance.

 

Completely agree with this, but 1 question. I hear a lot, and I mean a lot of people claim that SD is easier than the MAF. I can calibrate the MAF in 1/4 of the time it takes to do a VE table and it's MUCH simpler to me. How are you going about calibrating the VE table that you believe its easier than the MAF?

 

SD uses ideal gas law, there is no calibration as long as your sensors are reading temp and pressure correctly. It is also greatly flawed which is why OEM’s don’t strictly use SD anymore. (that I’m aware of).

I haven’t read up enough on the MAF tuning and don’t use it, so I’m no use there. I don’t see how the average DIY hot rodder can verify that the MAF readings are accurate though. Unless you were setup with a ton of expensive test rigs like the OEM’s use I’d think the numbers reported back from the MAF would be a guess. Similar to SD. Then the tuner uses the 02 readings to trim from there. Which is fine and does work… but that doesn’t mean the MAF reading is super accurate representation of the air the engine ingests. Would be cool to know for sure my engine was taking in exactly 90lb/min of airflow VS “X”lb/min fuel flow.

 

I posted this earlier, but my shiny new VW GTI 2.0t has no MAF.... Havent looked too much into how the ECU works, but it box stock at this point

 

Wasn't RonSSNova saying the new mopars are all speed density from the factory?



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