I was wondering I have a 86 roc with a pretty highly modified engine on a stock air intake (the y-pipe deal with the 2 little sqaure filter two little $5 STP filters in there) I want to know how much of a difference I would get if I put on one of those K&N's that mount tirectly to the TPI throttle body?

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I find your lack of faith disturbing

86 IROC .040 305 TPI
#186 Heads shaved .040 1.98 valves
Shorty Headers 3 in exhaust with Flowmaster
Lunati 259/271 .500/.515 cam
Highly Modified 700-R4
B&M Slapshifter
3.55 Posi Rear
Accel Plugs and Wires
Petronix Flamethrower Distributor
Cragar 15x7 front 15x10 rear

 

If you don't have mass air, then I imagine it would work just fine. You see that setup on a lot of oldschool musclecars with TPI swaps.
Obviously you would be pulling in warmer air. But you sure wouldn't have a lack of air, like you may have now.

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Mario,
White 94 Z28
Yeah I got a few mods
Video
Black 87 IROC-Z

 

We will know shortly

I have been wondering this myself. When I hook up the dataloging equipment to my car I max out my MAF at 195 grams/sec. And my motor is modded.... I wanna find out so I think I will try it.

 

actually it will probobly slow the car down,nothing like constant 100 + intake air.Drive your car around town for a few miles,that ck intake air temp.Do you want air that hot to be what the engine is breathing??

 

Crap. I forgot that I had a MAF. Well what differece do you think the 2 little square K&N's would make over those cheapo STPs I have for filters now.

Also I hear people talk about altering their MAF all the time, what exactly do people do to it and how do I go about doing it?

 

keep the plastic Y, but you can port some of it, remove some of the plastic just inside the end that connects to the maf, there is probably a small "hump" in there, and you can trim some of the plastic just inside the front part near the filters. i did that on my old iroc.

as for the maf, trim the fins off the inside...CAREFULLY!! and remove the screen, you'll pickup about 150 cfm.

i'd look into the homemade ram air setup, drawing air in from around the fog lights, i had that and it made the car pull like craxy above 50mph!! and i live in florida so there is plenty of rain, but never had trouble. if you don't wnat to do that just cut the bottom out of the air box, just below the filters...that will help air flow.

 

http://www.tpis.com/CatalogPages/images/300-144.JPG

and have you looked into ported plenums?

 

That's true, but actually, the stock MAF flows more than enough for even modified engines. Also, the screens add turbulence and even out the airflow across the diameter of the intake. This is what the MAF was calibrated for. Without the screens the airflow in the center may exceed the calibration speed and you'll get error codes showing up. Look at it this way, if you remove the aerator from a water faucet, you're removing a restriction, but the water comes out in an odd shaped stream due to large turbulence effects. With the aerator in place, there are no large turbulence effects, only small ones, and the water flow is much more uniform. This is the way more people are looking at this these days.

And about the intake of hot under-hood air. A 30° increase in air temp results in about a 10% reduction in oxygen concentration available for burning the fuel. And under-hood air is easily more than 30° warmer than outside air. People convinced me that an open filter in the engine bay was not as good as piping in cold air from some remote location.

 

I've got K&Ns, and I cut out the bottoms of the air boxes(baffles). Pop one of the filters out and you'll see what I'm saying. All that plastic can go. Just leave the upper part for the filter to sit in. I also cut out the rear screen only from the MAFS. You probably want to leave the front one in.

 

Ok guys, time for some hard answers to this speculation here. Check my sig for my mods. I have a cam thats much higher lift than the stocker and I still only flow 195 grams/sec through my MAF. I have taken the screens out of it so it is capable of flowing more air. The problem here is that a MAF maxes out at 255 grams/sec based on the source code that controls it, you simply cant meter more than that without changing code or developing a translator. Anyway, I have a lot of work to do to get my motor to require that much more air. ( By the way, I max the motor out at 195 g/s at 5800 rpm.) So trimming the heat sink in your MAF would not be beneficial if you don't need 300 + grams/sec. The point here is air velocity. You need a column of air to move fast, you put it in a smaller tube. You want a lot of air moving slowly? Put it in a large tube. The same applies for the TPI setup. Think about it. Thats why 305's usually don't benefit from the Big Tube runners. They just flow too much air at too low velocity to really cram it into the cylinders.

I vote Ram Air instead of MAF porting. Also, port your plenum yourself, I wouldn't pay someone to do that for me. I could do it in a few hours on a saturday morning or somthing.

 

Can you give me a site or something giving information on how to do this. Mostly what I need would be the numbers to tell me how much metal I an take off and still function properly.

 

Best site I have ever seen on porting plenums..

http://www.gmtips.com/3rd-degree/dox/tips/tips.htm

Check it out all kinds of free mods that you can do...