It does. Bends create turbulence and different diameters of tubing affect velocity.
It does. Bends create turbulence and different diameters of tubing affect velocity.
RM CMC Director
I think that’s a lot more physics theory than practical impact. Have a look at the OE LS air inlet system upstream of the TB and tell me it conforms with any known guidance on things like diameters of straight pipe upstream of the maf, avoiding large cross sectional changes, or non smooth profiles.
Al Fernandez
Disrupting/changing the airflow for the MAF can definitely have an impact. When Glenn and I were first working on a restrictor for the LS he made one that we put right in front of the MAF. Car wouldn't rev or pull about about 2,000-2,500.
I just have practical experience-no thermal velocity dynamics theory and it's impact on turbulence in a sphere of tubing. Where's my Bud Light Cody?
Bryan Leinart
CMC #24
Putting a restrictor immediately in front of the maf is a bit extreme when talking about air inlet design not mattering. I was considering reasonable things like 3.5 vs 4” tubing, a 90 vs a 45 etc.
Al Fernandez
Well it can and does, here are some stock MAF calibrations to prove it. The value is airflow in grams per second. First is a stock 5.7 Vortec truck.
5.7 Vortec Truck.jpg
Next is a Chevy Express van. Same 5.7, same MAF, different intake tract.
5.7 Vortec Express Van.jpg
Now an LS1 Camaro. Same MAF, different intake tract..
LS1B Camaro.jpg
Now an LS1 Corvette with the same old style MAF as the Camaro and different intake tract.
LS1 Corvette.jpg
Now an LS1 Corvette with the later, 6.0 type larger MAF. Same intake tract as older style MAF, just larger tubing and MAF housing.
LS1 Corvette 2004.jpg
And now a C5 Z06 with the same MAF, same intake tract, but the MAF came descreened from the factory. These cars in particular are sensitive to aftermarket cold air intakes and have a bit of a tendency to throw a check engine light and need a MAF recal to run properly. Fortunately mine has not done this with the Hurricane ram air intake.
Attachment 1839
Last edited by Supercharged111; 01-18-2019 at 09:46 PM.
RM CMC Director
And as a proof of concept I unplugged my cam sensor this morning and, lo and behold, the truck ran the same as always. No difference that my butt cheeks could feel, so apparently he's correct when he says it throws the PCM into batch fire mode. Since this scheme retains a distributor spark is unaffected. For reference again my truck is the 5.7 Vortec that he constantly refers to in his video running the 411 PCM. If you have a 96-97 OBDII car this literally only requires the PCM with an appropriate tune to no longer rely on the optical sensor within the optispark unit. For everybody else, swap out your crank pulley hub, timing cover, and add that 4X reluctor. They can be found on OBDII F bodies or on the myriad of 96-02 5.7 Vortec engines piled up in junkyards. I may actually look into guinea pigging this if it's something you're willing to entertain Al.
RM CMC Director
Still driving around with no cam sensor, gonna see what it does to my fuel economy.
RM CMC Director
That's cool stuff!
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