I recently put a new engine in my 97 z28 (stock engine). I am going to take out the cats and all the emissions like egr and a.i.r. Pump. I made my own block off plates at work with the cnc machine for the egr, but as for the a.i.r. Is all i need to take out is the black pump and the tube that goes from one header to the other correct. I know there's no hp gain i just want the engine bay to look more open i bought the pacesetter race headers and going to go true dual. And i'm taking the headers and mufflers to work tomorrow to weld on some flanges that i will make also. Do you think it will sound good from header to muffler,and will i still need the o2 sensors or can i get them all programmed out. I going to send my pcm in tomorrow to madz28 or madtuner.

And the next thing i need advice on is making my own crossover tube that goes in back of the heads. What fitting sizes do i need and what type of hose, i was going to get some goodyear hyd. Hose. I plan on starting up this weekend so any info will help.

 

exhaust sound is a funny thing. Never quite gets to where you want it. I will tell you this, the best sounds always come from a system that has cats. My only explanation is they filter out high frequencies and allow only low frequencies.

You'll need to get the EGR monitor programmed out as well as the rear O2s. The front O2s must stay as they are used for fuel control in closed loop.

 

Here are the components of the AIR system. You don't "need" to take anything out. How much removal is necessary to make "the engine bay more open" is up to you. Note that the exact components that are in the system depends whether the AIR pump recall was done on your car.

Courtesy of Shoebox:

http://shbox.com/1/air_pump_recall.jpg

You have to cap off any vacuum lines, and you have to cap the AIR pump inlet air hose connection on your air intake ducting.

Your car has 4 O2 sensors. You can delete the after-cat sensors, and have the resulting codes "programmed out". You have to keep the pre-cat sensors, because that's what the PCM uses to control the A/F ratio. It is possible to run an open loop tune, without the pre-cat sensors, but you don't really want to do that.

The best steam tube (crossover at rear of engine, and then to the throttle body) conversions I've seen use -AN fittings and braided SS hose. You indicate that you plan to use "hyd" hose, which I will assume is hydraulic hose. Does the hose stand up to high temperatures? Does the hose stand up to ethylene glycol? Neither of those conditions is typical of a hydraulic hose application.

 

That's good advice and a timely reminder to make sure that the hose will survive in that application. I use 1/4" pipe thread sealed with teflon liquid thread sealant and AN fittings with good quality (Aeroquip, Earls, etc.) braided line, either #4 or #6. The driver's side gets a 90° elbow, the passenger side gets a 1/4" pipe "T" and the line doesn't necessarily have to go to the throttle body. On race cars, I put a plugged fitting at the end of a stub line and loosen it to allow air bubbles escape when filling the cooling system. That eliminates an extra line running through the engine compartment.

Good luck,

c

 

yep the lt1 has a different sound than a gen1 sbc thats for sure.. you would think since the firing order is the same and with a good working ignition system they would sound good, some reason they dont sound anything like a gen1 sbc.. might be the d port heads..

i recently swapped my single in dual out flowmaster to a single in single out thrush and its alot louder but i dont really care for the sound of it, it sounds good but it doesnt have the deeper tone like a gen1 has, its seems higher pitched, wants to have a glasspack sound sorta..

the next thing i try will either be a small glasspack or a bullet type sprintcar muffler where the catalytic converter was, maybe a 12 or 16 inch log one just to tone the exhaust down a little more.. that or i have an old 3inch single in single out magnaflow i might try...

 

I bought some thrush welded mufflers.3" in and out single. My plans for the exhaust has changed a bit. I'm going to try to try to get a muffler shop to weld on flanges to the headers and the mufflers and run it like that and see how it sounds.with the mufflers bolted straight from the headers. and thanks for the advice on the crossover tube guys.

 

Having the mufflers dump directly under the front seats is going to resonate inside the car. I ran that way for a while with 3" Borla XR1's on the collectors, and everything inside the car vibrated. I added 3" pipes back to the axle and it made it a lot quieter inside the car.

http://www.injuneer.com/images/photo.../DCP03675a.jpg

 

so do you have the borlas welded straight on to the headers. I like the set up you got. nice. I think Im going to end up doing something like that in the future but now my funds have kinda been limited so i have to make do with what i got. I can get pipe if i needed it. and a question. What fittings will i need like sizes and types, I know cnorton told me but i'm not familiar with the fittings. and what lengths of hose do I need. Jegs only sells the steel braided premade at 2'.

 

would a -4 an fitting size work?

 

My exhaust system was originally a 3" CarSound cat bolted to each collector flange, a flanged 3" Y-pipe to a 4" Mufflex catback. I had the Borlas made to match the cat dimensions, so the cats could be dropped out for the track (C16 leaded fuel). Eventually I deleted the Mufflex catback to save weight, and because the Y-pipe interfered with the Gear Vendors O/D unit. So now its just the Borlas bolted to flanges on the collectors. They aren't actually the "collectors". I run AS&M singe cat headers, that have been modified to allow them to be used with true duals, so there is an extension on each collector, then the muffler bolted on.

For the steam tube, I'd use -6AN fittings and hose.

 

The fittings required to complete the basic steam tube in #6 braided line would be:

Jeg's # 555-100144 (2 required)
Jeg's # 555-100001 (2 required)

or

Summit # SUM-220647 (2 required)
Summit # SUM-220690 (2 required)

The existing holes in the head appear to be a non-tapered 1/4" pipe thread but the tapered pipe threads on 555-100144 or SUM-220647 will seal if they are prepped with teflon sealant.

Cut the hose to length (I prefer to cut braided hose by wrapping the desired cut-off point with a couple of inches of duct tape, securing it in a vise, and cutting directly through perpendicular to the length of the hose with an abrasive cut-off wheel on a die grinder. Wear eye protection. Remove the tape and carefully attach the hose ends.)

To extend the line to the throttle body or into a stub line for the purpose of relieving trapped air bubbles, additional fittings are required. If anyone is interested in this format, I can walk you through the list of fittings required. Not all of them are listed in the catalogs but they are available if you specify what you want to the order-taker.

Be advised, installation of this line, especially with #6 AN, is a tight fit against the firewall. It requires a substantial level of patience to connect the lines if the motor is already in the car. Using #4 helps the situation somewhat. I've never run this on a street vehicle so I don't know if there is a real benefit to one size over the other. The factory system is referred to as a "steam" pipe instead of a "coolant" pipe so I have assumed that the critical element is merely to relieve trapped pressure, not to move a specific volume of coolant from one side of the block to the other.

In any case, great care MUST be taken to eliminate the air bubbles from the system. An air pocket trapped in the back of the block could lead to catastrophic overheating of one or more of the back cylinders. I bleed off trapped air through the stub line as well as through the factory bleed valves when filling the cooling system. Typically, after the first few fire-ups, I continue to find it necessary to check and top-off the coolant level. I do not use a factory recovery system.

I have a picture of the system I used on my race car. It shows the crossover and the "T" fitting that leads to a stub line but the stub line is not attached in the picture. I will be glad to share it with anyone who wants to see it if an e-mail address is provided. Feel free to PM me your address. I don't know how to attach pictures to posts on this forum and I'm not particularly interested in acquiring that talent.

Good luck.

c

 

thanks a lot guys. i guess i'll order from summit. thanks again cnorton for the sizes of the fittings for the hose end do you just push the hose in to the end with the barb. I'll probably route it to the throttle body. yeah its just going to be just a street car for now. I know i need a tee. I'm also thinking of taking the tube to a company called northwest hose and see if they can make me something similar to it thats easier to install and uninstall.

 

If you have access to a commercial hose company, that would probably be your best bet. The braided line that I used is as simple as "just push the hose in to the end with the barb." Assembling AN fittings and braided lines is another issue altogether.

Be sure to calculate the distance between the two holes when the heads are bolted on the motor.

Good luck,

c