bad camaro RS

i had someone tell me they read you could only get 375 hp with a maf car this is worrying me cause i jus got my new afr 195cc heads and im hoping for more than 375hp please tell me the maf will flow enough to support more power i also heard something the the maf cant read high enough to support more hp any info id GREATLY APPERCATED thanks

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1992 camaro RS
373 10 bolt rearend
ssm sfc's
87 350 TPI
bored 30 over
compucam 2032 with 1.6
482-495 LIFT 214-220 duration full roller rockers
msd6AL
1 5/8 headman headers
2 `1/2 flowmaster exuast
k&n filters gutter air box gutted maf
3 pc under drive pulleys
no emissions no egr etc
custom ED Wright chip
eddelbroc intake base and runners ported plenum
midly ported and polished stock heads
Taylor 8mm wires
B&M mega shifter
gutted maf/airbox
hotchkis lower control arms
3" exhuast cutout
homemade cold air intake
2000 tci stall
700R4 with B&M shift kit
new best ET 13.5 @104.66

Willie

iTrader: (1)

I could take a guess on HP estimates, but won't. I will tell you my personal results though.

On my "MAF'ed" engine, I was dynoed at 421 rwhp. With my supercharger producing only 6 psig boost on my 305, my VE (volumetric efficiency) was calculated at 138 percent. That's equivalent to a 431 cubic inch engine with a VE of 85 percent (a standard figure used for a modded naturally aspirated engine).

Also, it's interesting to note that my MAF airflow values are maxed out at 255 g/s when I'm in boost.

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Willie

Supercharged 1987 305 IROC-Z, Daily-Driver, Emissions-Legal.
12.57 @ 111 mph.
12.04 @ 114 mph (50-hp nitrous).
http://members.optushome.com/au/downunder1/rides/willie/willie.html

1987 "20th Anniversary Commemorative Edition" Z28 Convertible -- Super Chevy Show Class Winner, 1998.

My custom front marker lamp assemblies:
http://members.optushome.com/au/downunder1/misc/lens.html

bad camaro RS

so since your maf tables were top out is that the most power you can make? is there any way to get your maf to read higher? thats very impressive hp out of a 305 thanks

------------------
1992 camaro RS
373 10 bolt rearend
ssm sfc's
87 350 TPI
bored 30 over
compucam 2032 with 1.6
482-495 LIFT 214-220 duration full roller rockers
msd6AL
1 5/8 headman headers
2 `1/2 flowmaster exuast
k&n filters gutter air box gutted maf
3 pc under drive pulleys
no emissions no egr etc
custom ED Wright chip
eddelbroc intake base and runners ported plenum
midly ported and polished stock heads
Taylor 8mm wires
B&M mega shifter
gutted maf/airbox
hotchkis lower control arms
3" exhuast cutout
homemade cold air intake
2000 tci stall
700R4 with B&M shift kit
new best ET 13.5 @104.66

Willie

iTrader: (1)

Good questions to which I don't have answers. I've asked several times whether the electronic saturation point of the MAF design is actually in the MAF itself or the ECM. I have not received an answer.

I reach the 255 g/s saturation point at approximately 3,000 rpm at WOT. This value remains constant until 6,200 rpm (my shift point). The dyno was run only to 5,200 rpm and at that point, the hp was still on the rise. So it's a safe bet to say that horsepower is not a direct relationship to MAF readings.

I makes sense that my "real" airflow readings above 3,000 rpm at WOT is greater than what the MAF is reporting. This leads to a question; if the MAF is capable of reading values greater than 255 g/s (or ECM capable of receiving), would I make more power? How the ECM adjusts its output parameters beyond this electronic saturation point is not known. Can anyone help us out here?

Willie

86TpiTransAm

Personally, I've disconnected my MAF before and noticed ZERO difference in performance....the down side is that your annoying SES light is on when it's not hooked up!! Also, a friend of mine had a fuel injected '83 Anniversary T/A and his MAF actually exploded on him ....most amazing thing I ever saw other than my other friend throwing his fan through the hood of his truck about 500 feet into the air!! Anyhow, his car ran just fine w/out a MAF from then on! I don't even really see the point in them myself but it's obviously got some sort of advantage over speed density because GM went back to using MAF in '98 and still uses it in the new cars!!

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1986 Trans AM
305 TPI
Completely Stock
Soon to upgrade to a 327 TPI with pocket ported 64CC heads, comp cam, TPI air foil, Adjustable Fuel Pressure Regulator, possibly bigger injectors!
Current project: Installing an Accel Inline Fuel Pump since I've been through 3 Fuel Pumps in 2 Years! :-(

Grim Reaper

Willie, the problem appears to be the ECM itself.

Go to this link https://www.thirdgen.org/messgboard/...ML/000265.html Its an interesting discussion about the 255 gm/sec limitation of the 165 ecm and possible solutions.

Merry Christmas!

Kevin91Z

iTrader: (1)

GM went back to MAF in 1994+ LT1's and newer. The newer MAF system is better than both TPI MAF and TPI SD, but its my opinion that TPI SD is better than TPI MAF. Your opinion may vary.

------------------
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

Grim Reaper

I agree with Kevin. I've been getting into PROM burning and you can do so much more with the SD ecm. It has limitations and things I wish I could do. But when you look at what you can mod on the 165 ecm (MAF) and then the 730 ecm (SD), you quickly see the 730 was definitely an evolution. Hell you have a chip with twice the size with the 730. That should say something in itself.

Grumpy

You can only got to 375 with proper resolution. The Buick Turbos are limited in the same fashion, and run 600+ with the stock MAF. Just set the fuel for WOT and best MPH, and take you *licks* with some poorer resolution.

MAP, and MAF are 2 very different systems. The down side to the MAFs, is that they are poor in sudden transitions, since there is always some response lag in it reporting new numbers compared to a MAP that is about instantaneous. But, in steady state, they can be slightly better, since less filtering is needed.
The later MAFS can read to 512 grms/sec.
There are 2 different later ones the 3" (LT1) and the 3.5" (LS1). I've also, run the 3" retrofited to where a Bosch was installed oem, and there is no comparision, the newer ones are a whole new animal.
Running with the MAF disconnected puts the system into Alpha-N. Fixed timing, if I'm not mistaken. Some cars seem to run good that way, but I'd never recommend it. The one I put a stop watch on was much slower, then with the MAF connected.

85ZZ4TPI

I live near tpis, one day I stopped there for some parts and they showed me a 500hp 406c.i. small block using mass air and their miniram.

IRACE87

According to TPIS the MAF system can support up to 550 hp (with proper programming)and over that they suggest to switch to SD.

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1987 IROC w/T56 and a 383 TPI in the works

88IROCs

The MAF tables on a stock $32 prom may give a clue to the actual flow capacity of the OEM MAF. Of the 6 tables, the last one(the 6th) is the most interesting. While the other 5 tables have 9 rows, the last table has 17 rows - the last 9 seemingly redundant.

----------------------------------------
; Mass Air Flow TABLE 6
;
; TBL = 1.00 * gms/SEC
;
;----------------------------------------
LC6D4: FCB 255 ; TBL SCALAR
LC6D5: FCB 16 ; 16 LINE TBL
;----------------------------------------
; gms/SeC BIN VDC #/HR
;----------------------------------------
FCB 207 ; 206.2 1536 4.39 1591
FCB 213 ; 212.2 1552 4.43 1637
FCB 219 ; 218.1 1568 4.48 1684
FCB 226 ; 225.1 1584 4.53 1737
FCB 233 ; 232.1 1600 4.57 1791
FCB 240 ; 239.1 1616 4.62 1845
FCB 248 ; 247.0 1632 4.66 1906
FCB 255 ; 254.0 1648 4.71 1960
FCB 255 ; 254.0 1664 4.75 1960
FCB 255 ; 254.0 1680 4.80 1960
FCB 255 ; 254.0 1696 4.85 1960
FCB 255 ; 254.0 1712 4.89 1960
FCB 255 ; 254.0 1728 4.94 1960
FCB 255 ; 254.0 1744 4.98 1960
FCB 255 ; 254.0 1760 5.03 1960
FCB 255 ; 254.0 1776 5.07 1960
FCB 255 ; 254.0 1792 5.12 1960
;----------------------------------------

As you can see, most of the values are maxed in the 8th row. Even though the voltage continues to increase, the airflow is reported as constant(254 gms/sec). Scaling up using this table, 5.12 VDC(the highest value) would be equal to an airflow value of 276 gms/sec.( 5.12/4.71 x 254 ) It would appear that the MAF can recognize airflow in excess of 254 gms/sec, but the ECM can't. Possibly the limitation here is the FCB counts, which can only vary in a range of 256(0 - 255). Another limitation may the ratio of the table itself( 1 * grams/sec). If the table ratio were rescaled to a value of 0.92 * grams/sec, would it possible to have the ECM recognize 276 grams/sec of airflow? I don't know, but it would be a tricky proposition at best. The first row of values in any table must match exactly to the last row of values in the previous table. So changing the ratio in one table would require doing the same to all the other tables. As the other tables have higher ratios(table 1 has a ratio of 11 * grams/sec), changing the ratio in the lower numeric tables may have an effect on idle and low speed airflow accuracy.

While the design of the OEM MAF seems to limit max airflow, there are are aftermarket MAF's available for TPI. While all of these aftermarket MAF's claim to offer improved airflow over the OEM unit, I don't know how they report this increased airflow, or even if the ECM will accept the increase.

As a final thought, <a href="http://electromotive-inc.com/home.htm">Electromotive</a>(the only aftermarket standalone EFI that can use MAF) sells several MAF meters. They claim that their largest unit, 80 mm, can support 675 hp.

El Guapo

The number 255 is the same as 2^8 (256). (You count the 0 as a number). lf these were 8 bit processors or had 8 bit storage capacity, that would explain the number. The ability to go to 512 on later models seem to indicate a 9 bit storage ability.

When it comes to how its handled inside the box, l do not know. But ld thought ld share that thought for any who may have not considered it.

Clayton

88IROCs

I'd already come to the conclusion that the max 255 FCB count was a limitation of an 8-bit addressing scheme. However, I do not understand why the ECM appears limited to accepting max. airflow of 254 gm/sec. The airflow is reported via an analog voltage and converted to back to airflow using lookup tables. If the tables were rescaled so that a given voltage corresponded to higher airflow, would the ECM accept and respond to this higher airflow? And if an aftermarket "high-flow" MAF were flow tested, and the analog voltage it reports was recorded, could the tables be rescaled to correspond to it's flow characteristics?

irocz

If that modern musclecar adaptor lets buicks run the lt1 maf is there any reason it won't work on a tpi? Don't the stock mafs on both cars max at 255?



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87 IROC-Z, 5.7, auto, 3.27, leather, !cat, Holley fpr, K&N'S, SLP 1-3/4" Jet-Hot coated headers, SLP .218/.224 .495/.502 cam, Comp 1.5 roller tip rockers, $uperPITAram, Edelbrock lower intake, Holley 52mm tb, Dynomax\Flowmaster catback. Coming Soon(?)- Fasttrack/Accell DFI

1989 Pontiac 20th Anniversary Turbo Trans Am - 161,000 miles, !cat, 9" K&N

88IROCs

That's a good question. I know there are some differences between the Buick and Chevy MAF's, but seeing as they both seem to be limited to the same max airflow(255 gms/sec), there may be some commonality. If using the translator allows you to employ the LT-1 or LS1/LS6 MAF, then for me this definitely is something worth investigating(in fact I will definitely drop MM a line regarding this). The only concerns I have revolve around the cost(swapping over would cost between $400 and $500)of item that may not improve performance if you are not already flow limited, and reliability(fuel economy, drivability and emmissions).

Does anyone here have any experience with the <a href="http://www.modernmusclecar.com/">Modern Musclecars</a> MAF Translator, and whether it is suitable for use with a TPI MAF ECM? If not, I will report back here, if and when Modern Musclecars responds to my inquiries.

bad camaro RS

im wanting to run better than 12.5 on motor so im hoping there is a way around this maf id go speed density but my maf has been so reliable and i havent a clue how to burn proms i know ive heard its easy but i jus dont understand the tables well enough

------------------
1992 camaro RS
373 10 bolt rearend
ssm sfc's
87 350 TPI
bored 30 over
compucam 2032 with 1.6
482-495 LIFT 214-220 duration full roller rockers
msd6AL
1 5/8 headman headers
2 `1/2 flowmaster exuast
k&n filters gutter air box gutted maf
3 pc under drive pulleys
no emissions no egr etc
custom ED Wright chip
eddelbroc intake base and runners ported plenum
midly ported and polished stock heads
Taylor 8mm wires
B&M mega shifter
gutted maf/airbox
hotchkis lower control arms
3" exhuast cutout
homemade cold air intake
2000 tci stall
700R4 with B&M shift kit
new best ET 13.5 @104.66

88IROCs

Never mind the question about changing the ratio. Since the Scalar value cannot exceed 255(darned 8-bit addressing), a ratio numerically lower than 1.00:1 would not be possible. Changing the ratio to 0.92:1 would require changing the Table 6 MAF Scalar FCB(address: LC6D4) to 277. Ugh! should have paid more attention earlier when I was studying the MAF tables,.... Duh!

irocz

I've got a couple of lt1 mafs lying around...what are they worth? is there any way to test them?

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87 IROC-Z, 5.7, auto, 3.27, leather, !cat, Holley fpr, K&N'S, SLP 1-3/4" Jet-Hot coated headers, SLP .218/.224 .495/.502 cam, Comp 1.5 roller tip rockers, $uperPITAram, Edelbrock lower intake, Holley 52mm tb, Dynomax\Flowmaster catback. Coming Soon(?)- Fasttrack/Accell DFI

1989 Pontiac 20th Anniversary Turbo Trans Am - 161,000 miles, !cat, 9" K&N

85F-body

i heard that if you take the screens off the maf it gives you more hp also could you take a 91 maf and replace it with an 85 maf would the prom work with the new maf or would you have to recalibrate???

Kevin91Z

iTrader: (1)

No such thing as a 91 MAF. What did you mean to say?

And the jury is out on whether removing the screens on your MAF sensor hurts or helps. I've heard both sides.

85F-body

well i just wanted to know if there was a more efficiant M A F than the 85 model (what does a 91 have a M A P or is that even tpi )

88IROCs

There are several alternatives to the stock TPI MAF. The most affordable($45) one is to send TPIS your existing MAF and have them modify it. They remove the screens, grind-off the fins and smoooth the walls. Granted you could do all this yourself, if you were brave enough. But I assume TPIS would replace the MAF if they damaged it during modifications.

TPIS claims the stock MAF flows a max of 529 cfm and their mods improve it to 790 cfm. Of course you would need a larger TB and a custom PROM to take much advantage of the gain.

Kevin91Z

iTrader: (1)

Either the 86-89 MAF system or the 90-92 MAP system is better than the 85 MAF system. It was GM's first attempt at TPI and the system as a whole is really lacking compared to the later stuff. If you're feeling adventurous, you can swap to the 89 MAF system, or the 90-92 MAP system, and have a much better running computer and engine management. A cheaper alternative is to get just the 86 TPI MAF wire harness and computer, as its a direct swap for an 85. As far as which is which, here is a timeline:

85-89, Corvette and F-Body: TPI MAF
90-91, Corvette: TPI MAP
90-92, F-Body: TPI MAP
92-93, Corvette: LT1 MAP
93, F-Body: LT1 MAP
94-current: Corvette, F-Body: LT1/LS1 MAF/MAP combo