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Author Topic: 90mm MAF housing over stock 80mm Z20LET MAF  (Read 45608 times)
kelesha
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« Reply #30 on: January 08, 2013, 03:11:48 PM »

an 85mm MAF should be good up to 700ish HP.
Yes, but if its not BOSCH HFM5 Smiley
85mm internal diameter HFM5 will finish on around 500hp on crank if not die many times before that Smiley
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kelesha
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« Reply #31 on: January 08, 2013, 03:18:44 PM »

Torque peak is late because of GT3071 and because intention is to protect clutch and gearbox. Dyno is made in 4th gear, on a F23 diesel gearbox, which means aprox 240km/h in 4th gear at 7000rpm.
With 3071 turbo on that engine, torque need to be at least 800rpm lower........when you have full spool ?
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nyet
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« Reply #32 on: January 08, 2013, 03:35:32 PM »

Yes, but if its not BOSCH HFM5 Smiley
85mm internal diameter HFM5 will finish on around 500hp on crank if not die many times before that Smiley

Why would it die? Air velocity is air velocity, regardless of diameter.
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kelesha
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« Reply #33 on: January 08, 2013, 03:53:23 PM »

It will die because its BOSCH, thats simple.......its made that way by factory i.e to have limited life, sometimes its really "limited" Smiley Anyway regardless of diameter if HFM5 stays around 50-60cm from turbo it can last some time........
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alexs307
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« Reply #34 on: January 08, 2013, 04:02:06 PM »

With 3071 turbo on that engine, torque need to be at least 800rpm lower........when you have full spool ?


I have seen cars tuned by famous companies in Europe, even 600bhp rated ones, once this engine goes to GT30 or over, I think it is impossible to have max torque at less than 4000revs, usual power figures show max torque at 5000rpm and beyond.

Mine is building 1.5-1.6bar of boost at 4500-4800rpm.
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kelesha
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« Reply #35 on: January 08, 2013, 04:18:23 PM »

600hp are not in GT3071R power range, they are suitable for GT3582R, and you cant compare spool between 3071 and 3582 so torque curve will be very different between these turbos. Anyway with 3071 you need to have full spool before 4000rpm, if not, something is not right on that engine.........
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Robson
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« Reply #36 on: January 08, 2013, 04:38:22 PM »

how far is this Maf curve from yours , i have known this one to work . Unsure what housing it was in tbh but if it helps you out then bonus
Id say altering ignition low down would help with the cutting out possibly ,
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Rabbid
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« Reply #37 on: January 08, 2013, 04:48:34 PM »

I wouldn't say Seimens Deka 60lb's are shitty, infact even tuners who don't properly map in TVUB still manage to get them running pretty sweet at low idles such as 750-900rpm and still pass emissions tests. Heck I've even had Seimens Deka 80lb's idling perfect with cams on a Z20LET.

In regards to not having a MAF curve or not being able to make one, if you have a dyno and a wide band you can make one. Disable fuel trims set the desired fuelling and measure the error and correct the MAF curve easy.
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Rabbid
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« Reply #38 on: January 08, 2013, 05:14:33 PM »

But what I would add is on the Z20LET's running 11's at 450bhp on a Z20LET with Seimens 60lb's will probably be at about 100% duty on Z20LET's hence I am going 80lb's after about 420.
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nyet
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« Reply #39 on: January 08, 2013, 05:16:55 PM »

It will die because its BOSCH, thats simple.......its made that way by factory i.e to have limited life, sometimes its really "limited" Smiley Anyway regardless of diameter if HFM5 stays around 50-60cm from turbo it can last some time........

Dunno. I avoid bosch and always use hitachi, regardless of MAF diameter, for the reasons you state Smiley
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« Reply #40 on: January 08, 2013, 05:19:18 PM »

In regards to not having a MAF curve or not being able to make one, if you have a dyno and a wide band you can make one. Disable fuel trims set the desired fuelling and measure the error and correct the MAF curve easy.

If using a known maf (hitachi or bosch) just scale MLHFM to theoretical using area (or dia) ratio to get in ballpark. Then use KRKTE, KFKHFM and KFLF to fine tune. Fine tuning individual points on MLHFM is a huge waste of time.
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« Reply #41 on: January 08, 2013, 05:28:03 PM »

I would disagree you don't have to perfectly scale all 512 values but you can get a percentage error for a range of the curve and correct on that percentage.

Applying one equation over the whole thing from old size to new size hasn't ever come out anywhere near what I've seen in use on other vehicles which the larger MAF's actually fitted.
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nyet
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« Reply #42 on: January 08, 2013, 05:40:19 PM »

I would disagree you don't have to perfectly scale all 512 values but you can get a percentage error for a range of the curve and correct on that percentage.

Keeping it monotonic and smooth is a huge pain.

Doing % corrections in KFKHFM is exactly what that map is for. Why not do it there? Plus you can correlate it with load/rpm, generally shows more consistent error patterns than simply vs MAF voltage.

But hey, it if works for you, it works for you. There's more than one way to skin a cat.
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« Reply #43 on: January 08, 2013, 05:45:15 PM »

I´m considering he veryfied BOV and it didn´t gone open after the pull.

As I said, when I beggin calibrating with big injectors and Ethanol there is a plenty of modifications to make idle well, and allways involve TUVB and TEMIN... sometimes because I use Ethanol there must be some "torque reserve" map modification

Regardless if it sticks open or not, it is irrelevant.
What is relevant is that he dumps measured air to atmosphere, so the fueling will always go very rich when you lift the throttle.
And as I said before, even funnier when the valve does not open at lower transients and causes the MAF value to zig zag. You can guess what happens with timing and fueling at that moment...
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nyet
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« Reply #44 on: January 08, 2013, 05:52:22 PM »

But prj, there are 1000hp + cars running BOVs! That means BOVs are good.
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