Z/28 Exhaust Inquiry

[MX621]

Originally Posted by Yessa

I've decided to do the following but stay stock.

- Tune

This should give me a little extra hp without the extra noise or gas odors.

Fixed it for you.

[Yessa]

Understood. Thank you.

[joelster]

Originally Posted by ariZona28

For the minimal benefit you will get from boring ( I assume you mean porting, cleaning up) the exhaust manifolds it may not be worth the effort unless you have them off for other maintenance. Entire back seat assembly top and bottom is approx 40 lbs or so. With driver on board and 1/2 tank of gas car is over 4000 lbs. Might not give you much gain power/weight ratio and now you have a valuable seat laying around. Cutting plastic to MAYBE increase airflow to one of the best factory intakes Chevrolet has made? Could make things worse and might be costly to repair if unsuccessful. If there was anything to gain from intake mods the aftermarket is always all over it. I don't know much about tuning. Maybe crank it up for 93 octane. If you've done some serious mods (heads, cam, exhaust) then I would say a tune is a must, that much I know. My car is all stock (for now) and I enjoy the strong acceleration and minimal maintenance required for 505 hp/481 ft -lbs of tq. I guess the point I'm trying to make with all of my ramblings is that if you really want noticeable power gains with the LS7 you're going to have to plunk down some cash and do some serous wrenching.

^^^^This guy gets it. I did longtubes along with an MSD Atomic intake. My car baselined on the dyno at 482/476. My tuner showed me everything. I was pumped and figured with his tuning I'd hit 500. When he got out of the driver seat I asked him "Will it hit 500?". He said no way. The factory tune is pretty damn good. The only point of the graph where it was really off was from idle to around 3500. At WOT it was decent. Up near 12.9-1 or so. He tweaked it and found 10hp and 7ft-lbs for a finish of 492/483. That was adding a little timing and leaning it a teensy bit. On a bone-stock car you're possibly looking at getting 5hp, maybe 6. Tunes run from $400+. Not really worth it.

I've said it before, the biggest restriction in the exhaust is the cats, period. If you eliminate the cats, you'll free up some power. It wouldn't surprise me in the least if someone were to fabricate an off-road pipe for the factory manifolds, and compare them to a set of dedicated longtubes, that the factory pipe/no cat setup would be within 3-4hp of the $1700 set of aftermarket headers.

The biggest restriction in the intake tract is the intake manifold itself. Not the TB, not the factory CAI system. Nobody ditches the factory Z/28 CAI setup because it moves enough air to feed 700hp. You're putting a lot of work into your car for minimal to zero gain.

[pzero]

Originally Posted by Brutale arancia

A very polite way of saying don't turn a very well engineered high performance vehicle manufactured in limited quantity into something less than it is in current form.

Another very polite way of saying. If you want to play, you got to pay = mo powa baby!

[z28monster]

The stock Z/28 exhaust is actually very good. Add a mild or aggressive HCI package and the car will sound like no other car you've ever heard before

[SS Performance]

How is the ground clearance with the ARH and Kook's long tube headers?

[Yessa]

Originally Posted by z28monster

The stock Z/28 exhaust is actually very good. Add a mild or aggressive HCI package and the car will sound like no other car you've ever heard before

Any recommendations?

[Yessa]

Originally Posted by SS Performance

How is the ground clearance with the ARH and Kook's long tube headers?

Good question.

[MrRaZ28]

Originally Posted by SS Performance

How is the ground clearance with the ARH and Kook's long tube headers?

ARH is practically the same as the stock manifolds in terms of clearance. I have zero issues.

[GeneRoss]

Originally Posted by MrRaZ28

ARH is practically the same as the stock manifolds in terms of clearance. I have zero issues.

I'll 2nd that. No issues at all.

[DasBaldDog]

Originally Posted by GeneRoss

I'll 2nd that. No issues at all.

I have no issues, but I DEFINITELY lost about an inch-1.5" at the collection spot.

You'd have to hit a weird break-over type bump to hit it (and you would have probably scraped going over regardless) but it IS there.

When I get home tonight I'll take a side profile of the underside where the headers are, you can SEE them hang down, like I said that inch-ish.

[joelster]

Originally Posted by SS Performance

How is the ground clearance with the ARH and Kook's long tube headers?

Exactly like stock:

[SS Performance]

Originally Posted by joelster

Exactly like stock:

I might have missed it but what headers are you using?

The picture helps a lot, thanks.

Craig

[ariZona28]

Originally Posted by joelster

Exactly like stock:

I hope that's not one of those defective Chinese Harbor Freight jack stands assisting you in the infamous Z/28 3-point hover. Kinda scary.