How do you know if you are choking your motor for air in front of the throttle body?
My TPI swap I did worked beautiful, and I got the air intake with the MAF to work very well. The problem is I had to run a relatively small K&N filter. I just have this gut feeling that the small filter may possibly be hurting my performance, and I could make a bigger one fit, but that will be alot of work, and wont look nearly as nice. So before I go through all the hassle of redoing my intake setup, how can I see if the filter is a cork? I dont really want to take it off and try without it because the filter is right on the MAF and the screens are out. Has anyone else ever thought of this, or am I strange? Thoughts?

 

As long as the filter has more area then then the throttle body bores you should be ok. You could drill a small hole and hook up a vacumn gage and see if you generate any measurable vacumn. With a real sensitive gauge like an airplane altimeter you'd probably just get a small blip when flooring it from idle.
Another way is purposely block the flow so you can see exactly how the engine runs when it does have some restriction.

 

Comparing the filter area to the size of the TB is utterly and completly incorrect.

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1991 Firebird
350 L98 (was a 305 TBI),T-5,Edelbrock TES and cat back,Accel manifold
NOS,subframes,jegster torque arm,MSD Digital 6
AFPR,Lakewood lcas
Hurst linelock,SLP cam (206 212 .480 .486),relocated battery,cold air,Hypertech chip,centerforce df,clutch
poly bushings and mounts
AFR 190s
Harland sharp 1.5 rockers
autopower rollbar

12.33 @ 114.83 juiced uncorrected

13.510 @ 102 non juiced uncorrected

 

If you have a scan tool, you can measure your MAP reading with the key on, but not running and record this value. Then make a WOT run and record the MAP values vs. RPM. If at any point your MAP value is less than what you recorded earlier(usually at highest rpm), you are getting pressure drop thru the air cleaner or throttle body or both.

 

1) he has MAF not MAP.

2) MAF has a max of ~500cfm, most K&N's are 600 to 1000+ cfm depending on size, so I would say your fine but, if your worrying about choking your engine (depending on ci 305 or 350+) I would worry first about the MAF setup then the airfilter.

Also let us know what size Engine and the RPM range you plan on working in, so we can better help with determining what your engine should need.

But I would say if it is a K&N even if it is small it should flow enough. But then again bigger can't hurt.


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1989 Trans Am GTA - Flame Red Metallic, L98 5.7L TPI, TH700-R4, T-Tops, 3.27, 9-bolt rear, dual cat
- K&N Air & Oil Filter
- Dynomax muffler

1992 Camaro RS - Hawaiian Orchid, LO3 5.0L TBI, T-5, T-Tops, 3.08, 10-bolt rear - Sold
- K&N Air & Oil Filter
- L69 Dual Snorkel

 

Thanks for the replies. It is a 355 with all of the common stuff done to it. 52mm TB, ported and siamesed plenum, SLP runners, Accel 22# injectors, Comp .510 114 LSA roller cam, AFPR, Accel SR base, headers and big exhaust, and soon a set of ED 6085's with mild bowl work when they get back. After driving the car a little and beating it, I would guess that I will be shifting right around 5000-5200. The filter is connected to the maf ad it has an outside diameter of 4.5" and is 4" long. Do you think it is too small? Please tell me what you think.

 

Just try it without the filter and stop guessing. Seriously, the odds of you sucking up something significant enough to hurt your engine is next to nil. People have been running cars w/ no aircleaner since the dawn of the IC engine.

Other than that, i just wanted to note that since you're talking about a custom set-up, ideally you want to have the MAF as close to the TB as possible. If you've relocated the MAF much further away than it would be on a stock firebird than you might start getting into a little bit of inaccuracy weirdness, as the MAF will have an even bigger lag from the actual airflow into the engine.

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Ed Maher - Moderator @ The TPI & Carb Boards
92 Z28 Convertible - Quasar blue / Tan top
305 TPI A4 2.73 - 14.74 @ 93.25
Stock except ported plenum and dual cats
-=ICON Motorsports=-

- Definitely prototypes, high powered mutants of some kind. Too weird to live, too cool to die