Joe Prince

When you port a MAF (center divider removed) I understand that it will give you more timing but will it lean the motor out? or enrichen the mixture? and is the mixture change across the board?
Thanks!

J'sRamAir

A ported MAF should lean you out, but i'm not sure if it's all through the rpm range though.

J&JsTA

When I ported the MAF in my 97 5.7L Vortec it leaned out the motor throughout all modes,(Ltrims +8%to+11%)cruise as well as WOT. So much in WOT that it created KR of 1.4-3.2. I purchased a MAFT but have not had a chance to install it and do some ATAP runs.

[ January 14, 2002: Message edited by: J&JsTA ]</p>

Joe Kizzire

Joe from what I've learned from playing with a LS1edit program the pcm looks at maf, tps, map and iat inputs and comes up with a calculated load value/rpm table to determine timing.

I hope I haven't confused you but what I'm trying to say is there is alot going on with the timing besides the MAF.

WeatherGuy

You need to be careful porting a MAF 'cause you can end up running way too lean and get the detonation from hell. It's not fun punching it, and then hear what sounds like loud spark crackles at about 5000 RPM.

Gee . . . does this sound like personal experience speaking . . .

Ragtop 99

iTrader: (7)

You lean out the mixture accross the board when you port the MAF. You are allowing more air to pass through than it is calibrated for. You can measure the change by ATAPing your LTRIMs than switching to the ported ends and ATAPing again. The change in LTRIMs should put the non-WOT A/F ratio back to normal.

Joe Prince

Okay, this really helps, I am stuck at 11.9 - 12.0 AF across the board with 25 - bearly 27 peak timing and when I lean the base 1 click via MAFT it makes a huge impact to 13.8 to 14.0 and detonates! and thats why I was looking for another way to creep into the 13.0 range. I have never removed the middle bar out of an LS1 MAF but I may just remove the front one first and check for any change in the AF and timing. Thanks! more input excepted!

TXCAMSS

iTrader: (60)

Joe , If you have an Atap and MAFT, you can port both ends of the MAF and tune it to where you want. I find that on my 01' it runs best with the Ltrims at 10-12 which is a little lean.This is primarily during the cooler months.You may have to go a little richer in the summer months to eliminate the pinging.By going +1 on the base you are actually richening 10%. I measure my Ltrims at part throttle cruising say 2nd gear at 3000 rpm.Ltrims don't mean anything at WOT.Once you get the ltrims set, then start on the O2s at WOT.You should be shooting for .880-.910s. Be sure to watch the KR on your WOT runs and be sure to give you car some miles to learn each change.Personally I would do an idle relearn procedure with MAFT at 0-0 , then give it 50 miles to learn and then start making Ltrim adjustments and then the WOT O2s.Hope this helps.

JS

iTrader: (4)

Joe after talking to Ed Left,Julio,and Steve Cole about MAFS the best bet is a stock descreened maf w/LS1 Edit programming on a Dyno w/WB.

Now on a bif motor the bigger mafs do help along wlarger TB but on a 346CI I would stick with your velocity ported 1/2 and keep talking amterial out til u get the desired 02's/ on the wb

JS

hawkls1

hi joe this is tony with the red firehawk I have a set of whisper maf ported end that you could try out and see what happen.send me a e-mail if you would them to try at hawkls1@aol.com

ChrisB

I would stick with a stock de-screened unit also - esp. if you have the ability to tune it with LT1 edit.

If you feel you need more airflow the switch to the z06/6.0l 85mm MAF. here are the appropriate tables (from a z06/6l pcm
Freq (Hz)
1488 1616 1744 1872 2000 2128 2256 2384 2512 2640 2768 2896 3024 3152 3280 3408 3536 3664 3792 3920 4048 4176 4304 4432 4560 4688 4816 4944 5072 5200 5328 5456 5584 5712 5840 5968 6096 6224 6352 6480 6608 6736 6864 6992 7120 7248 7376 7504 7632 7760 7888 8016 8144 8272 8400 8528 8656 8784 8912 9040 9168 9296 9424 9552 9680 9808 9936 10064 10192 10320 10448 10576 10704 10832 10960 11088 11216 11344 11472
Flow Gm/sec
2.3 2.7 3.1 3.6 4.2 4.7 5.4 6.1 6.8 7.6 8.5 9.5 10.4 11.4 12.6 13.8 15.1 16.5 18.0 19.6 21.3 23.0 24.9 26.9 29.0 31.1 33.4 35.8 38.3 40.9 43.7 46.7 49.8 53.1 56.5 60.1 63.9 67.8 71.9 76.2 80.6 85.2 89.9 94.8 99.9 105.2 110.6 116.3 122.1 128.1 134.4 140.9 147.6 154.5 161.7 169.1 176.8 184.7 192.8 201.1 209.7 218.6 227.8 237.3 247.1 257.3 267.9 278.9 290.3 302.3 314.8 327.9 341.6 355.9 371.0 386.8 403.4 420.8 439.2
"

Rock01T/A

how much power do you gain from all of this sounds like a lot of trouble i hope its a lot