Stock exhaust upgrades
I have a low mileage (47K) 1995 Z28 4L60E/3.23 car. I just got the car and am working on starting to mod it. I wasn't expecting to drop $450 on repairing the AC, so that's taken some of my "catback" funds.
At what point would the stock necked down intermediate pipe (where it necks to go into the muffler) become a HP restriction?
I don't have an exhaust pipe expander handy, but are there real...not "go to a muffler shop" options to replace the muffler and tail pipes in my garage?
Years ago I would have just grabbed a Dymomax muffler and pipes and gone with that, but I see they offer very little for the LT1 cars these days.
My main concern is getting a decent set of tail pipes. Mine are good enough to reuse, but I believe they are a mere 2.25" ID.
Any thoughts?
Thanks!
Dave
Utterly Unrepentant LT1 Owner
Save up some bones for some longtubes from tsp or pacesetter, a y-pipe, and a gmmg catback and you'll never have to touch the exhaust again
If I have to get by with just a K&N AF only and the Magnaflow, I'll probably do that.
The GMMG style exhaust sounds really nice...looked at it years ago for another car, but choked on the asking price.
Even though pre-OBD2 cars no longer get tested here in the People's Republic of Illinois, I want to retain as much of the OE Emissions as possible.
The longer term plan is for a set of ceramic coated emissions compliant shorties, Magnaflow y-pipe (single cat car), and the aforementioned exhaust.
From there I plan to move on to the suspension, before doing a 12 bolt and mild 383 or 396 5-10 years out.
With two girls in school, money comes in small quantities for at least the next 5-7 years.
If there are LTH's that can be non-Kalifornia compliant and will fit without a lift and/or tubular K-member, I'm interested.
The car will get driven 2000-3000 miles a year and carry the family out and about...something as loud as a NASCAR Cup car just won't fly here.
Thanks
-Dave
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Be patient and save your money. U have a nice car - enjoy it as is until your ready to do it right,
cardo
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Be patient and save your money. U have a nice car - enjoy it as is until your ready to do it right,
cardo
Sorry but scavanging is developed by tube length and matching tubes to the firing order. And with the limited choice of smog legal headers (all shorties) there ain't much can be done for that.
Restriction and backpressure is what we are fighting with a single pipe, single cat exh. A 3" maybe better than a 2.25 (only = 3.97sq" flow area) but a 4" reduces restriction a whole lot more. If u have only modest plans then 3" (= 7.065sq" flow area) is fine but if look to the future for big power 4" (= 12.56sq" flow area) will get the job done.
I don't even want to hear the "too little backpressure myth" unless u have some real data to back it up - no hearsay BS please. Even with 4" u will have plenty of packpressure. I have never seen a super stocker or pro stocker at the drags with anyting but open header.
cardo
For headers try to find some used single cat SLP mid lengths they come up in the classifieds or c-list once in a while. Mac mid lengths are good too.
Restriction and backpressure is what we are fighting with a single pipe, single cat exh. A 3" maybe better than a 2.25 (only = 3.97sq" flow area) but a 4" reduces restriction a whole lot more. If u have only modest plans then 3" (= 7.065sq" flow area) is fine but if look to the future for big power 4" (= 12.56sq" flow area) will get the job done.
I don't even want to hear the "too little backpressure myth" unless u have some real data to back it up - no hearsay BS please. Even with 4" u will have plenty of packpressure. I have never seen a super stocker or pro stocker at the drags with anyting but open header.
cardo
You'll be SHOCKED at how much that face intrudes into the flow path. Start by "gasket matching" the manifolds with a die grinder or Dremel tool. You'll free up a lot more flow there, and then you can worry about the flow downstream....
The car is a long term project and will probably end up a lot tamer than the badass tuff I see you guys have.
My goal is to be able to outperform a mildly modded 2011+ "New 5.0" Mustang GT in most respects without sacrificing driveability, streetability, and do it on a reasonable budget a few pieces at a time.
Being able to shut up the LS1 owns at the gym would be a bonus, LOL
The Wife put up with my 65 LeMans for 15 years despite the lack of creature comforts. Adding loud/nasty anything just won't fly.
I also intend to do all of this while retaining the emissions gear even though OBD-1 testing has ended here in Illinois.
The first step is a new exhaust system....as it so happens the OE is pretty rusty from sitting, and a CAI.
Next spring I hope to work on upgrading the suspension, do a front LS1 brake upgrade, wheels (C5 Z06) and tires. If the $$$ Gods smile on me for a change, it will get a Harwood cowl hood and 96-97 SS rear spoiler.
Hopefully then I can move on to a 12 bolt or S60, cam, ported heads, and maybe 4-5 years from now, a relatively mild NA 383 or 396.
Thanks!
Dave






