I have a 85 trans am with a 305lg4.
My question is.How much horsepower would I gain approxiamatly with a k&n filter in the stock air cleaner,and putting aftermarket headers on headmen,hooker etc.
Thanks
Rob

 

1 or 2 from the air filter, and 10-30 from the headers.

------------------
West Coast GM Shootout 2001!
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=-

 

10hp from filter 20-30 from headers. Keep in mind u might need a catback exhuast system to get the full effect of the headers. I also suggest the Power induction system up above. Those are mainly for LG4 motors such as yours. With the power induction, filter,Headers,catback exhaust u could get a possible 15-20 hp at the rear wheels. Not bad for a few bolt ons

------------------
92' camaro
New 305 block TPI conversion, Flat top pistons,Bore over .30 Forged parts all around,Edelbrock intake,ported plennum,ported corvette alluminum heads, accel cam,52mm throttle bodie, SLP runners Home aid cold air induction, Air foil,ford SVO 19lb injectors,fuel regulator,cloys timing chain, comp alluminum roller rocker arms and pushrods MSD 8.5 mm wires, bosch plattinum plugs, hypertech cap & rotor and coil, Edelbrock TES headers, free flowing catalytic converter and a 3 inch force II flowmaster exhaust system, and a 3 inch cutout,Zoom multi friction clutch, T-5 tranny,billenstien shocks&struts.
Soon to come!!!
Procharger system 12lbs o boost.
New paint job(hawaiin orchid purple)Cast alluminum ZR1 rims w/ 275 tires.
Favorite quote: "where ever u go, there u are"

Other car;
1971 plymouth Duster
Mods:340,edelbrock victor jr. intake, 650 4 barrel holley, heddman headers,40 series dual flowmasters, cold air intake,4:10 gears, just got a new paint job and cragar rims with 315 tires in the back.
:Yeah its not a chevy but damn how many 71' dusters have u seen in the streets.

 

If you put a set of headers infront of stock exhaust set-up, it won't do much for your car. The headers will out flow the rest of the system by a mile and will cause insane turbulance which won't do much to help with horsepower numbers. IMO, you get a good cat-back system from Hooker, Flowmaster or Edelbrock. That along with the K&N will do more for your car then the headers and the K&N will, plus it will be less expensive and MUCH easier to install. My headers took a week to install, my cat-back took 2 hours.

------------------
1987 Chevy Camaro IROC-Z
L98 TPI 350 (5.7L)
TH 700R-4 Transmission
Borg Warner 7.75" 9 Bolt Rear End

Current Mods: LT4 Hot Cam, Comp Cams 1.52:1 Roller Rocker Arms, Edelbrock TES 1 5/8" Headers, Hooker 3" Aerochamber Cat-Back System, Performance Resource Chip, Accel Ignition Coil, Cap, Rotor, 8.8mm Wires, K&N Filters, JET TPI Air Foil, All Free Mods, Falken ZIEX Z-Rated Tires.

Best ET (w/o LT4 cam): 14.32 @ 97.7mph
(corrected for elevation)

7.5" 10 Bolt with 3.42s soon to come!

 

You're dreaming if you think you get 10 HP from a K&N filter, or any air filter...

 

 

Thanks guys it helped my decsion to buy headers.I already have a custom exhaust set up.
I can't wait to get a 350.My Gm dealer has a new z34 ? for $7000 putting out 355 hp.Or just get a rebuild for 4000.

 

When I called K&N, they said the filters give a 5-10% increase in power.

------------------
Looking For:

87 IROC-Z 350 TPI
84 TRANS AM 305 H.O.

 

5 - 10% is a ***** gain a air filter cant give you that much

 

LOL!!!!

------------------
Looking For:

87 IROC-Z 350 TPI
84 TRANS AM 305 H.O.

 

It's been my experience that K&N's stuck in a stock induction system make little if any noticeable difference on anything from our cars to trucks, mainly since the airfilter is often not the most restrictive point in the system on a stock car. However, a K&N in a performance intake will allow much better performance. Personally, I wouldn't bother with them unless you modify the induction system, then after that it's a mod worth the money.

 

From the K&N Filters, you can get anywhere from 1-20 hp gain, but it all depends on how the air is circulated to get to the filter and how much of it is getting there. If you have a stock Air cleaning system, then you will prolly get 1-3 hp gain, with an open element, prolly around 4, and with the ram air effect with a ram air box and a ram air hood of course, prolly 10-15.

------------------
87 FireBird Formula<BR>
305 4bbl LG4<BR>
K&N Filter<BR>
Flowmaster 80 Series<BR>
3 inch tips<BR>
Holley Quadra-Jet 650 CFM 4bbl Electronic Carburetor<BR>
"General Tires" P215/65R15<BR>
-----Need Upgrades-----
--Give suggestions plz--

 

gg sig

------------------
87 FireBird Formula<BR>
305 4bbl LG4
K&N Filter
Flowmaster 80 Series
3 inch tips
Holley Quadra-Jet 650 CFM 4bbl Electronic Carburetor
"General Tires" P215/65R15
-----Need Upgrades-----
--Give suggestions plz--