Large capacity Bosch Maf

[GazM3]

Hey chaps.

Just tuning my m60b40 with air/air intercooler. I’m maxing out the Porsche 803 maf at just on 5000rpm even with a voltage offset of 0.7v so the computer sees only 5v at an actual 5.7v at the maf.

I know there is a Porsche 809maf (1200kg/h) but I think I’m going to max this out or close at the 7000rpm cutout.

We have got a pretty good tune considering with full throttle around 11.5:1 a/f at max rpm but it goes pretty rich at around the 5k mark 10:1.

Im running 60 lb/h injectors with an adjustable fuel pressure reg set at 2.4bar (from the std 3.5 bar). I also have the std 404 ecu with the ess chip and a basic (but effective) jaycar DFA that lets me alter the fuel at 128 load points on the maf.

Am i stick with the biggest maf as an 809 or surely there is something else available. I can’t easily go to a larger housing than 3.5”.

Can the maf handle more voltage safely than 5v as i have the ability to scale the voltage offset more if need be.

Thanks in advance.

Btw car is running very strong just leaving power on the table at 5000rpm to 5800ish. Ahh the joys of tuning

[vwmikel]

Why not just use a MAF emulator?

[JimsR]

Obd1?

[tofunin]

Hey Gary, you can drop some voltage by adding a 2.2k ohm resistor to get you to up to 7k.

[GazM3]

Hey Gary, you can drop some voltage by adding a 2.2k ohm resistor to get you to up to 7k.

That’s what we are doing in next day or so.

Its an obd1 404 ecu.

Just put a boost gauge on today and it’s making 10psi @7000. Wondered why it felt so strong. Not a huge amount of traction in first and 2nd barely hooks up with 3.15 diff. Running pilot super sports and the lsd is definetly 2 wheeling. After having reliability issues in past few years and it was running effectively on the limp home mafless signal and it would barely break traction in first unless u provoked it.

Im starting to understand what all the fuss is about now.

[Gmfwd]

I use a Nissan slot maf in a 3" tube on a MS42. There really cheap. In a 3.5" tube with a 2.2ohm resistor they should handle some serious power.

[Def]

Nissan N62 MAFs (came on 300ZX VG30DETT and VH45DE V8's in Q45's etc.) can measure about 550 rwhp out of the box. VQ curves for the MAF are readily available online. They're dirt cheap, I've sold them with pigtails before for like $40.

[NickG]

Are you 'tuning' it by altering the MAF signal? Or are you actually adjusting the software in the eprom?

Sounds like you're hitting the max airflow value in the software, and not necessarily a 5v voltage limit or such.

[GazM3]

Definetly hitting the max voltage. Put more offset into it and it’s sorted the hump. Still there is no room to boost up any more. The 8x 60lb/hr injectors are at 70%duty with 2.4bar @ 10psi. It feels really strong. Even 2nd you have to be pretty have to modulate the gas pedal in the dry which I never had to do before. I’m running a 3.15 goodnworking lsd and Michelin Pilot supersports so its not like they are no grip Chinese specials.

[BadBoostedBmwM3]

Wow!


The man is back...?


Nick G knows what's up.

[NickG]

Definetly hitting the max voltage. Put more offset into it and it’s sorted the hump. Still there is no room to boost up any more. The 8x 60lb/hr injectors are at 70%duty with 2.4bar @ 10psi. It feels really strong. Even 2nd you have to be pretty have to modulate the gas pedal in the dry which I never had to do before. I’m running a 3.15 goodnworking lsd and Michelin Pilot supersports so its not like they are no grip Chinese specials.

Well I guess you know what you're doing then.....enjoy

- - - Updated - - -

Wow!

The man is back...?


Nick G knows what's up.

Thanks, LOL

[ba114]

if you're only tuning by altering the MAF, what are you doing about timing? Surely you're not running the stock timing based on stock load values when you're altering the MAF reading the DME receives?

Sounds like a recipe for disaster...

[GazM3]

if you're only tuning by altering the MAF, what are you doing about timing? Surely you're not running the stock timing based on stock load values when you're altering the MAF reading the DME receives?

Sounds like a recipe for disaster...

its running the ess chip which sorts the timing reduction under boost.

Ive ordered a genuine Bosch 809 (Porsche turbo 996) maf as the 803 is not an original Bosch. It has greater capacity in kg/hr. I can still use a voltage offset if needed.

U can actually make timing changes to how the factory maf reacts to adding or removing fuel. Want more timing add fuel pressure and remove fuel trim from the interceptor. Vice versa for removing timing.

[janithdg]

other than working with the stock ecu it will be easier for you to use an aftermarket ecu like speeduino and it will be cheaper and it uses speed density, if your using the stock dme route you will have to use a nissan maf of sort i've had great success with Hitach Slot MAF 22680-7S000, with slot type maf you could go blow-thru setup which is resistant to fast throttle close turbulence and Blow-off impact