BWilcox

Hi Guys,

I am considering building a fairly large SBC.

Based on Bore and Stroke (DART SHP Block), a 421 looks nice.

I am familure with how to tune the 165 $32B mask. At least for a street cammed 358 CID motor.

After reading a ton of information from this Website, most likely the MAF analog output will max out before the MAF becomes a flow limitation.

What happens to the fueling calculations when the MAF is output is maximized?

Does the ECU go into an N-Alpha Mode?

Are the calculations different for WOT vs. Part Throttle?

My goal is a street car with very limited drag racing duties.

I have not yet put together the complete package, something that runs from 1800 RPM to 6500 RPM seems good to me.

Any help would be greatly apprecited.

Best Regards,

Bruce

Twin_Turbo

iTrader: (25)

Cartridge maf + extended range 33b contact greg carroll

tequilaboy

With proper MAF, programming and injectors, the 165 ECM can support up to approx. 1,400 horsepower, so a naturally aspirated 421 is no problem.

A BA5000 sensor or equivalent in a 3.5" tube has enough flow range for about 4600 kg/hr.

If we rescale the airflow calculation into appropriate units, we can easily control fueling for big power.

Here's an example: A convenient mass flow unit for this purpose is myriagrams/hr. WTF is a myriagram? 1 myriagram = 10 kilograms, easy to convert to/from kilograms/hr.

1 myriagram/hr is equivalent to 2.78 gr/sec. As such, 255 myriagrams/hr is equivalent to 708 gm/sec and is sufficient flow to support about 1,000 hp with typical AFR and BSFC values.

Need to support even more power, use slugs/hr instead. 1 slug/hr = 4.05 gm/sec. 255 slugs/hr can support about 1,400 hp.

Since we are working with a mass based system, we can use any unit we want as long as the airflow and product of injector flow rate and base constant units match each other. The days of pegged MAFs and the perceived 255 gm/sec limitation are long gone.

Although these examples are extreme for discussion purposes, they are also realistic. Choice of sensor, housing and scaling should be tailored for the specific application, but the given examples will work for nearly all even if they are overkill.

Tuning is accomplished in the usual manner. Set the AFR target appropriately for the fuel and engine's needs.

TTOP350

iTrader: (8)

Is there somthing to replace the factory Bosch meter so we can have true 4" cold air intake ductwork ??

Tuned Performance

iTrader: (92)

a cartridge maf can be mounted in a 4" intake the maf scaling on the airflow will need to be changed.

TTOP350

iTrader: (8)

A cartrige maf from what?

Tuned Performance

iTrader: (92)

Ls (sorry)

Twin_Turbo

iTrader: (25)

Tuned Performance

iTrader: (92)

http://www.ebay.com/itm/LS3-5-Wire-M...2b71a1&vxp=mtr

BWilcox

Thanks guys,

If I understand you correctly, we basically take a MAF cartridge that is mountable in a tube to create a custom device.

Some more questions for you:

1.
I should select a MAF cartridge with a max output voltage of 5 Vdc. Correct?

2.
Scale the tube diameter so the MAF output voltage reaches maximum at an airflow that is slightly above the maximum expected airflow from the engine. Maybe a 10% margin?

Is this reasoning correct.

3.
What about the airflow measurement resolution down at idle and low speed conditions?

Are there engine setup issues to note that may exaggerate this potential issue?

4.
What is the best way scale the Injector Constant to work with the custom MAF?

I assume that the MAF cartridge has been characterized with some standard tube size. Assuming laminar flow across the whole diameter, I guess a new Vout cs. Flow Rate may be calculated from the size difference of the standard tube and the tube required for my application?

For example, if I double the Flow Rate through the MAF system at a given Vdc, then I need to set the Injector Constant to 1/2 of the actual value. Correct?

What is the best way to select the proper Injector Size?

Thanks again for the help.

Best Regards,

Bruce

TTOP350

iTrader: (8)

This is what I started back in 93ish, it's a 4" pipe. I have had it on the car and running but I need to finish the rest of the cold air setup.

BWilcox

Very nice work and picture!

I looked into the BA5000 and the VMP HPX 05+ MAF options. These are 0 to 5 Vdc Ford slot MAF devices. It looks like I would use a 3" tube to support my NA power levels.

The nice thing is a calibration file is included. I can just change the MAF tables in the ECU. Then the Load calculation will be correct and I will not have to modify the spark tables. In addition, I will not have to offset the Injector Constants.

Does anyone have experience with either of these devices?

Best Regards,

Bruce

tequilaboy

I have experience with all of the common Ford analog slot style sensors and application of these sensors in tpi cars.

The slot style sensor offers several advantages (in no particular order):

• Packaging/mounting flexibility
• Various measurement range options available
• Reduced flow restriction when used in larger housings
• Durability
• Low replacement cost
• Integrated IAT sensor
• Sensor availability
• Directional flow measurement and insensitive to reversion

Twin_Turbo

iTrader: (25)

Listen to the man ^^ He has helped me tremendously getting mu cartridge maf setup running

TTOP350

iTrader: (8)

Sooo If I'm picking up what your throwing down and I think I am. This will be no problem an play nice with factory stuff, It'll get ride of the tempermental Bosch sensor That I have a love/hate relationship with.
What needs to be done with the old MAF power and burnoff circuits/ relays?
Or should I just stepup to the LS computer and harness from EFI Connection?

Twin_Turbo

iTrader: (25)

The relays can remain, you will not be using them. You do have to swap 1 wire on the ECM connectior and get an adapter pigtail or make one for the stock maf connector + iat sensor since they both will be gone.

TTOP350

iTrader: (8)

Thats not a problem at all, I also have my IAT in my SLP cold air box so I could just add it to the MAF harness like the latemodel cars.
Which wire in the ECM is swapped?

Twin_Turbo

iTrader: (25)

MAF signal, green wire

http://www.blowerworks.net/sensor.html

TTOP350

iTrader: (8)

Very helpful. It's been a looong time since I looked for anything like this. I can't believe I hadn't seen this stuff B4 Thank you.

Orr89RocZ

iTrader: (20)

I thought the limitation was code in the actual chip. Hence reasoning for scaling injector constant and modifying the maf tables to cover more range at expense of resolution. Not sure exactly how that works with the code side of things.

I know i made my own 3.5" maf by taking stock maf internals, cutting it out of the factory housing and installing it inside a 3.5" pipe. Worked well but required alot of maf scaling to the point i only used maybe 3 tables out of the 5 or 6 in the 6e bin. I didnt scale the injectors or anything. Just maf scalars and maf table mods. Car didnt seem to gain anything but ran just as good even with reduced resolution

tequilaboy

A couple comments regarding resolution:

We are only limited by the ecm's 8 bit A/D converter. Each A/D count represents 0.02 volts or 20 mV. 255 counts = 5.12 volts. From the Motorola reference manual (hc11rmr3):

"When V

TTOP350

iTrader: (8)

My motor doesn't start pulling until 3,500-4,000rpm an pulls till 7,500-8k rpm fairly easy.
I can't wait to finish a few things and get a real tune instead of just the stock chip in it.
It should sing fairly well.

BWilcox

Thanks Guys,

Great information here.

However, somewhat confused??

I found a connector schematic for the FORD MAF/IAC.

Pin 1 : GY/RD : IAT Ground.
Pin 2 : RD : +12 Vdc Switched Power.
Pin 3 : BLK : MAF Ground.
Pin 4 : TN/LB : MAF Return.
Pin 5 : LB/RD : MAF Analog Output : 0 Vdc to 5 Vdc.
Pin 6 : GY : IAT

What about the GM MAF from Blowerworks? Is this a Analog Output device? Or is it a Frequency Output device with a convertor to analog?

Does anyone have a Connector Schematic for the GM MAF?

Thanks,

Bruce

PS. Still thinking about the MAF tube diameter. More comments/questions later.

Tuned Performance

iTrader: (92)

LS3-7

http://www.mouser.com/ProductDetail/...HFoXU0p1BTU%3d

tequilaboy

For clarity, everything I've posted on this topic refers to experience with the Blowerworks MAF and related products along with the general technology involved.

In this context, we've been talking about an analog sensor with Ford style connector. An adaptor harness is available from Blowerworks to allow simple plug-in installation to the factory harness mating connector.

Best bet is to contact Blowerworks.

Frequency based GM MAFs could be made to work, but this would tend to increase both the cost and complexity since a translator would be required to adapt the signal. Somewhat unknown territory.

BWilcox

Hi Guys,

Thanks again for the information.

So far, it looks like I need to move forward with the Ford based Slot MAF option as opposed to the GM based Slot style MAF. Much easier to work with an analog output!

I looked at the Blowerworks Website. Here is what I found for the L98 MAF.

-----------------------------------------------------------------------------------
Exact "Physical" Replacement MAF Sensor for Original Bosch L98 Unit

Price as shown above with "Bosch" OEM 'clip adaptors'
for L98 'Y' & 'F' Body vehicles: $399.00.


Description: Thin Film RTD Sensor similiar to the LS1/LS7 etc. MAF sensor.
Indestructible and can accomodate 600 RWHP (500 gms/sec).

Installation does require a new .bin file that we sell as follows:

Bone stock replacement bin: $99.00 with purchase of MAF sensor assembly. Stand alone price $199.00

SuperCharged bin with PulseWidth Cap Fix: $199.00
-----------------------------------------------------------------------------------

What confused me was the LS1/LS7 statement?

My guess is they are using either the SCT BA5000 Slot MAF or the HPX Slot MAF with a custom enclosure. Either one is analog.

I ran some simple 1st order calculations:

CFM=[ (CID*RPM)/3456 ]*VE

For a 421 @ 6500 @ 0.9, the CFM = ~ 713.

The equivalent flow in gms/sec = ~ 404.

It appears like the Blowerworks Bosch MAF replacement would work for my application? Not sure on the enclosure size?

What is your recommendation on the enclosure size?

Best Regards,

Bruce

BWilcox

Hi Guys,

I downloaded the Blowerworks L98 MAF document.

What is the purpose of the B12 (original MAF Input) to D8 (new MAF Input) swap?

Is the 1K pull-up resistor (on B12) too strong for the FORD MAF to work against?

What is D8? My guess is a spare analog input port on the ECU.

The code change is to re-map the MAF input port. Correct?

Best Regards,

Bruce