I figured out what the small piece of pipe going into the cat is. It is the AIR thing that ads air to your cat. I was told to remove that along with the smog pump. I saw the tech article but didn't really understand it. I dont even know which one it is in the picture.

The guy that told me all this said i would gain no power because of all the loss in back pressure. Want i still have some back pressure do to still having a muffler. Also i was told by people that it would gain in the higher rpms but lose some in low. Im putting in 3.73's (if i ever get off my lazy A$$)so wont i have plenty of low rpm power???

 

No gain in power because of the loss in backpressure? Uhh? you sure he wasnt thinking of a catalytic converter rather than the smog pump? Also, backpressure is always bad, I believe a functioning cat does increase scavenging by a small amount because of the honeycomb and the fact that it gets extremely hot (hot exhaust gas wants to move to cool air as fast as it can.. ie, out the exhaust pipe) but at the top end it can just pose a flow restriction

you dont need to remove the pipe to the cat just put a cap over the end of it... there is a slight power gain from removing the pump but its really mostly just to clean up the engine bay

Dont pay attention to all those people with their loss of low rpm torque propaganda I hear so much bs about that its not even funny

 

pablo is very right on this. all the back pressure that a 305 needs is built by having small diameter manifolds or headers. i run my car with 1 5/8" primary headers, not cat, and a borla cat back with the wide open plate and my car hasn't lost anything down low.removing the cat gained me .5 mph and knocked of .2 secs.

lata
tim

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91 Camaro RS-LO3,Auto.
14.301 @ 94.39mph
The car is going street strip for next season. 13's here i come!!!!!
Edlebrock TES Headers, Cat Eliminator Pipe, Borla Adjustable Cat Back,Marche Pulleys, HyperTech Chip,Transgo Shift Kit,B&M Convertor(2000stall),Steve Spohn Rear Rig( all rod ends), Poly Front Bushings,Ported TB, 350 Injectors, Edlebrock Performer TBI Intake, Performer Heads, 1.6 Roller Tipped Rockers
http://www.mycar.net/mafb/registry/detail.cfm?id=299

 

Loss of bottom end can always be made up for, by moding other areas of the motor. So, first you give up bottom end, and improve top end. Then you just do another mod, that puts bottom end right back up there, and give you boost in mid range or whatever. Now what do you have? Better horsepower throughout the range of the motor. As long as you dont have a turbo, you dont need much backpresure. And NJ SPEEDER is right. The manifolds or headers give you all you need. The only reason you dont want open headers is so cold air doesnt back up into your heads and warp them (i was told this by and old guy , dont know if its true anymore). An engined tuned for wide open exhaust is going to be stronger than one tuned best as it possibly can with a slightly restrictive exhaust.

 

yeah you wont get any big power gains, but it will look a hell of a lot cleaner when you pop teh hood.

go to a hardware store and get some brass caps to screw into the holes left in the manifolds, they are pretty easy to find. they look kinda funny having a brass shiny thing on a rusty exhaust manifold, but oh well.

or you could just do what i did...get a set of SLP stanless headers without the AIR tubes.

-brian

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1991 Camaro RS - Ultra Blue Metallic, T-Tops
----------------------------------------------
GM 350 HO Crate Engine - Vortec Heads, Edelbrock Performer Vortec Intake, Holley 670 CFM Throttle Body, Open Air Cleaner w/14"x3" K&N, SLP 1 3/4" Stainless Headers, Edelbrock Victor Series Water Pump, Accell Superstock Wires, Cap, and Rotor, MSD Blaster Coil, Hypertech Fan Switch & Thermomaster Chip, AC Delco Rapidfires, 3" Cat Back, Flowmaster 40 Series Muffler

700R4 - 2,400 Stall Converter, Vette Servo, Shift Kit, B&M Super Cooler

Brian's 1991 RS
Central NY F-Body Association
Join the Third Generation F-Body TBI Web Ring
z28boy@twcny.rr.com IM name: Z28 Boy

 

The only reason you dont want open headers is so cold air doesnt back up into your heads and warp them (i was told this by and
old guy , dont know if its true anymore).


Snflupigus, this is true with open manifolds, but not open headers. Most drag cars and Dirt track cars run open headers. The short length of a stock maniflod will allow cold air to suck back and burn/warp a valve. My car ran ran 2 tenths better dropping the Y-pipe off and running just shorty headers

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82 Z28 350, Ported #882 Heads, Performer RPM cam and intake, hedman headers,650 Demon carb,
Trans: Turbo 350 w/ 4000 stall -- Rearend 7.5 w/ Richmond 4.10's, Auburn Minispool
Future plans: Dart headed, Roller cammed 383 in early '01


89 RS, L03 305, Hypertech Chip,cat delete, Dynomax exhaust,K&N open element Filter,160 stat, MSD coil --Trans:700R4 Corvette Servo -- Rearend: 7.5 GM 3.42 w/ posi-lock
http://www.bassettracing.cz28.com

 

thanks, now i know.

hew those stainless headers. do they discolor from heat at all?

 

Mine did, and even got a little surface rust. They clean up east though, I just use a piece of steel wool every so often and they look brand new. You can see mine at my webpage http://www.theduke.cz28.com/photo.html
And they are the SLP headers, no AIR tubes, 1 5/8" size.

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1992 RS
327, Modded TBI, Rebuilt WC T-5 5-speed, PRO 4 15" rims, Nitto's, 3.73's, SLP 1 5/8" headers, and a few other things.

 

BTW, before, I was running the manifolds with a cat, 2 1/2 inch exhaust, and a very restrictive Dynomax Super Turbo muffler. Now I have the headers with no cat, 3 inch exhaust and a Flowmaster 80 series. It gained a whole lotta power, didn't loose any low end power, just gained some.

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1992 RS
327, Modded TBI, Rebuilt WC T-5 5-speed, PRO 4 15" rims, Nitto's, 3.73's, SLP 1 5/8" headers, and a few other things.