LT5 engine upgrade question

[1995BLACKZR1]

I've recently visited Marc Haibecks website and see that he does engine upgrades which is kind of intriguing... I think in about 3 years I'll be interested in upgrading to the 350ci engine which is 510 horsepower. Has anyone done this engine procedure or higher by Marc and can tell me what the experience was like and how do you like your car now?

I have a B&B exhaust so I don't know if that would make it cheaper.

[Paul Workman]

I and many others (can chime in too) can attest to the performance a pure joy the "500 package" upgrade for the 350 cid LT5 is!

And ALL of that performance comes while maintaining the stock block/bottom end, and cams. All of it is the result of turning the motor loose; letting it breath, with top-end porting and headers and lighter flywheel. You loose NONE of the stock driveability and reliability, while maintaining a stock idle!

The modification completely changes the personality of the car. What's not to like??

[We Gone]

Start saving your penny's now, the only thing you may regret is not going for more HP.

[1995BLACKZR1]

That sounds great. The person I bought my ZR-1 from says the B&B exhaust he had put on gives it 70 more horsepower. Would anyone know if this is true or not? I will be saving my pennies, why not especially if I'm gonna have the car for a LONG time. The horsepower is great on it now but why stop now :)

[JimZRyd]

I'm planning on sending my 94 to Marc hopefully in the next year and go for the 510 package or maybe one more step up. Depends on a few factors. I currently have a Corsa but have a new 3" B&B I want to switch out to. 70 more HP from just any exhaust seems a bit much. I don't even think B&B even advertise but like 20 to 30 max.

[Vette73]

70 horsepower? No way...The real gain when you touch the exhaust is the headers...When I swapped out my stock system for headers and exhaust I saw how restrictive the exhaust manifolds were on my 91.....That 510 package looks great and Marc seems like a very knowledgable guy when it comes to the LT-5..

[PhillipsLT5]

Marc & package TOTALLY LEGIT, adjust package to fit your wants, 500 HP really wakes car up, aprox 100 HP more at rear wheels over factory

[1995BLACKZR1]

Awesome. I really like how his power point presentation make it easy to understand. Good selling point. I would love to do it. I will be saving some pennies! If the 405 horsepower is this much fun I can't will until over 500 horses!

[diamond zr1]

and why stop there/600 h/power is really fun/go for cubic inch if you can//Phil's car will run with a new z06 and w/out the blower //at least in a quarter mile/

[1995BLACKZR1]

I saw the 650 hp engine upgrade was $30,000. Lol. I wonder if anyone has that upgrade? That would be amazing. It could beat about anything

[RICKYRJ1]

I did Marc 500hp pkg. love every mile of it. yes, you do save some $$ by already having the exhaust. It really woke the car up, you will not regret it

[Paul Workman]

I saw the 650 hp engine upgrade was $30,000. Lol. I wonder if anyone has that upgrade? That would be amazing. It could beat about anything

There are "a few" here in FBI country sporting 427 and 441 cubes, and one of them squirted over to NY to reside! AES will build you a closed deck, short-block LT5 suitable for force induction.

Lots of 368s and a few 380s around as well!

The up-side is the durability and the broad power delivery of the DOHC architecture. The down-side is there are so few LT5s that supply and demand makes it expensive to upgrade. The LT5 is a marvelous piece of engineering. But, when forced to buy billet crankshafts (and sometimes cams) vs. mass-produced, production parts. But, cost aside, the performance per cubic inch and the durability of a race-designed and hand-built motor is undeniable...and we have the trophies to prove it!

Champions of the Crown Point Corvette Club Shootout, 3 of the last 4 years...is largely testimony to the big inch LT5s, and one crazy fast, stock bottom 350 cid, aka Pete's Green Machine!

http://i185.photobucket.com/albums/x220/6PPC_bucket/misc/CPCC%202014_zpslmxod8c3.jpg (http://s185.photobucket.com/user/6PPC_bucket/media/misc/CPCC%202014_zpslmxod8c3.jpg.html)

Come September, the FBI gang will be defending the trophy again, and hoping to make it again for the 4th time. Go FBI and their ZR-1s!

[ZR1North]

I and many others (can chime in too) can attest to the performance a pure joy the "500 package" upgrade for the 350 cid LT5 is!

And ALL of that performance comes while maintaining the stock block/bottom end, and cams. All of it is the result of turning the motor loose; letting it breath, with top-end porting and headers and lighter flywheel. You loose NONE of the stock driveability and reliability, while maintaining a stock idle!

The modification completely changes the personality of the car. What's not to like??

Paul's comment is right on the mark! I had Marc do the 510 upgrade this past winter, and it is like a totally different car.

I went with Stainless Works headers and Corsa exhaust with Banks Engineering tips. I also had 4:10s as well as Hurst short shifter and line lock control installed. I opted NOT to have the single flywheel installed for fear of the "rattle" some cars exhibit at idle. It cost about 15 hp if I recall. It still dynoed at 490, and with the 4:10s, it's a fantastic package - all with the durability reliability that Paul mentioned.

Since the engine has to come out for this upgrade, it's also a good time to have the engine refinished. I had mine polished rather than repainted. I only have 1,700 miles on it since the rebuild (including some hard miles during the Mountain Run 3 in May) and thus far, I see no issues with maintaining the polished version. I asked Marc to apply Gibbs coating immediately after the polishing process to arrest oxidization; I am not sure if that is helping, but no issues to date - knock wood.

Bottom line - you won't regret the upgrade.

[GOLDCYLON]

That sounds great. The person I bought my ZR-1 from says the B&B exhaust he had put on gives it 70 more horsepower. Would anyone know if this is true or not? I will be saving my pennies, why not especially if I'm gonna have the car for a LONG time. The horsepower is great on it now but why stop now :)


70 extra HP with a B&B exhaust ? Maybe 10 HP might be an honest number. GC

[JThomas]

Marc is excellent to work with too! :cheers:

[WARP TEN]

I saw the 650 hp engine upgrade was $30,000. Lol. I wonder if anyone has that upgrade? That would be amazing. It could beat about anything

I'm sure it would be an amazing engine but as I am sure Marc stressed, the best bang for your buck and most reliable upgrade is his 350/510 package. That is what I have and have enjoyed it tremendously. It makes the car quite powerful yet it is completely reliable, smooth, easy to drive around town. Acts just like a stock ZR-1. To give it a bit more low speed quickness, I combined it with a 4.10 rear axle and also added a Hurst short shifter and electric cutouts to a stock exhaust system for adding rumble when I want it and an extra 10 HP for the occasional run at the track. Otherwise a stock car. I have only run it once at the drags (Beech Bend 2014) but it ran 12.4/116 without power shifting. And of course the very best value is to purchase a car which has already had the work done. If you are back in the Chicago area to see Marc again you would be welcome to drive mine to see what it is like if you have not already driven one. I am always glad to help Marc in this way if I can. --Bob

[Fully Vetted]

Previous owner paid the bill on mine but I can't imagine this car without the porting and headers. I did the Corsa exhaust and gears to finish it off but with 430 hp to the wheels on tap it's just a hoot to drive.

[Johnny5]

That sounds great. The person I bought my ZR-1 from says the B&B exhaust he had put on gives it 70 more horsepower. Would anyone know if this is true or not? I will be saving my pennies, why not especially if I'm gonna have the car for a LONG time. The horsepower is great on it now but why stop now :)

I have an article that came with my pizza box that states Borla cat back added 50 HP. There is no way that it is true but it was published.

[cvette98pacecar]

There are a dozen or so cars that are North of 700hp NA. And probably another 20 to 30 cars that are buzzing around the 650 range.

[Fully Vetted]

Are those BB cars, Robert? What's the strongest 368 that you've heard of?

[cvette98pacecar]

Are those BB cars, Robert? What's the strongest 368 that you've heard of?

Those are all 396 or larger, Mark H car if I remember correctly has a 385 that has 625hp without the power adder.
Todd is still trying to get 800hp out of a 427. Thinking he should install "Oh **** Handles on the Targa top".

For the 368 cu in. 530-550hp. I can honestly tell you that my LPE 368 would leave my DRM500 in the dust. However, I do not believe any of the LPE 368 have a fully ported top end, back in the day all porting was done to 34MM. Maybe Locobob has a fully ported 38mm top end with cams and fully ported and shaved heads.

Now Dom's car has to have the same numbers 530-550hp with a 350 bottom end.
Then there is the mysterious 350 that has to be putting out between 575 and 600hp. That car is just sick.

IMO if you are going to do a stroker, you either do a 396 like Dennis or a 402 like Phil. They both have the same horsepower as the 415 or larger cubic inch engines without all of the side loading.

[1995BLACKZR1]

Thanks so much for the information. How long does Marc usually need the car? Is he based in Chicago? The 510 package sounds great. Yeah I have read a lot on the LT5 motor and it's very impressive. One thing I like about this car is you don't see many C4's on the road anymore and it being a ZR1 makes it even more rare. I also want to switch the rims out for a deep set chrome type which I think will look amazing.

[cvette98pacecar]

Thanks so much for the information. How long does Marc usually need the car? Is he based in Chicago? The 510 package sounds great. Yeah I have read a lot on the LT5 motor and it's very impressive. One thing I like about this car is you don't see many C4's on the road anymore and it being a ZR1 makes it even more rare. I also want to switch the rims out for a deep set chrome type which I think will look amazing.

Pd Buck has a set of chrome, he is looking for stock wheels. Here is the link.

http://www.zr1.net/forum/showthread.php?t=25330

[XfireZ51]

It never gets boring driving a DOHC motor w 500+ hp under foot. The power delivery is smooth, effortless, and seemingly just goes on and on.

[Demps]

The top end ported 350s are an extremely enjoyable drive. They maintain stock drivability demeanor and pack a punch. If you have the coin to immediately go that route, I'd recommend.

Consider this though: if you can escape with headers in your area, put them on now. You'll want them with the porting. I've found stock '95s in the 345 rwhp range. Exhaust adds to ~360 rwhp (+~7 w/ x-pipe). Headers and chip with all above will get you to ~390 rwhp. All cars respond slightly different which I think is cam timing.

Marc's packages and his care are second to none. It does take time though. He can tell you and is usually in the ballpark.

BEWARE: whatever you do it will be just short of enough.

Evidence:
Stock
Stock with headers exhaust
Ported 350
Ported 350 with cams
415 with cams

Ted

[XfireZ51]

I have gone through a similar "evolution" as Ted with the exception of remaining in the 5.7L displacement class. Each step brought additional hp with it and the "need" to push on. The ported top end w headers is a really nice package but surprisingly (seriously) I found that ported heads + Pete's intake cams was an even better combo. So much so that I was hesitant to do the exhaust cams concerned w giving up idle quality and part throttle cruise for some additional power. Its taken a bit of time and effort BUT its definitely been worth it. More recently, I have been working on getting the tune right for the notorious free-wheeling decel surge and am pretty pleased with where its at. The accelerator is really smooth and I'm seeing an indicated 30-32mpg at 65mph on a level road. The exhaust cams are worth about 20rwhp from just the intake cams.

[Jagdpanzer]

Be careful, when it come to HP … to much is never enough

[LT5Vette]

I don't believe anyone is unhappy with any of Marc's upgrade packages. As others have warned horsepower like any addiction craves more and more and just a little bit more. I'm happy with what I have really, I am.
:icon_boun

[SAM/CH ZR-1]

A 368 with 510 HP pulls noticeable different (stronger) than a 350 with 510 HP. When it's about more cubic inches, go first with a bigger bore and longer rods. Make the crank leighter and the engine get a incredible trottle response.

[5ABI VT]

If he said 70 hp from exhaust... I would double check everything he told you. Are you sure the car is a zr-1 and not an LT1 with a sticker?

[1995BLACKZR1]

Lol. Yeah the car is legit. It's got what looks like an LT5 engine, engine valet key, ride control switch and the tail is wider than the standard C4. Obviously more horsepower and rumble than my standard 95. Maybe the exhaust place told him that.

[WARP TEN]

Thanks so much for the information. How long does Marc usually need the car? Is he based in Chicago? The 510 package sounds great. Yeah I have read a lot on the LT5 motor and it's very impressive. One thing I like about this car is you don't see many C4's on the road anymore and it being a ZR1 makes it even more rare. I also want to switch the rims out for a deep set chrome type which I think will look amazing.

Marc works best when he has the car and can work on it at his own schedule. He will estimate a reasonable schedule for you based on exactly what you want to accomplish. But it seems like there are always little emergencies from other people that pop up to interfere with a large project that he is very good about helping on. When I did mine I gave it to him in early December and said return it when you are done but sometime before spring. I recall it was ready by early March. But what was I going to do with it in the Chicago winter anyway? The 510 package is well worth it in terms of fun/permagrin :-D. Not so much for return on investment:censored:--Bob

[Bob Eyres]

My guess is that the B&B exhaust is worth 20-25hp on a 375hp. car. But that's if you've already got headers. I think mine (see mods below) is close to all you can do with a stock motor, and just bolt-on exhaust, no cats, no resonator, and an X pipe. Overall, it picked up 7mph. in the quarter, for 117mph. Thats over 400hp. at the crank, easy.
Marc's 510hp. package is the very best mod for the car, in my opinion. Because it retains the stock shortblock, which is what makes the ZR-1 so special, and durable.
I've been saving my pennies for a long time to have Marc do the top-end on my car. But I never seem to have an "extra" $10-15K.:rolleyes:

[Paul Workman]

My guess is that the B&B exhaust is worth 20-25hp on a 375hp. car. But that's if you've already got headers. I think mine (see mods below) is close to all you can do with a stock motor, and just bolt-on exhaust, no cats, no resonator, and an X pipe. Overall, it picked up 7mph. in the quarter, for 117mph. Thats over 400hp. at the crank, easy.
Marc's 510hp. package is the very best mod for the car, in my opinion. Because it retains the stock shortblock, which is what makes the ZR-1 so special, and durable.
I've been saving my pennies for a long time to have Marc do the top-end on my car. But I never seem to have an "extra" $10-15K.:rolleyes:

Well...know this! You can attack it in "bite-size" stages over time - leading up to the full package later, for a fraction of that expense. Perhaps as much as 2/3 of the benefit comes with 1/3 of the cost, before the heads have to come off - around 390 to 400 or so rwhp. This will put you above stock LS3's peak rwhp...which ain't too shabby! And, if you can do the porting yourself, you can cut the costs by $1500 ±.

BUT, BEWARE!!! Hp is addicting!! Sooner or later you'll want to do the heads too. But, at least by then you may have recovered from sticker shock of the first go-round, and be eagerly anticipating the next phase!:)

[Fully Vetted]

...Perhaps as much as 2/3 of the benefit comes with 1/3 of the cost...

So, so true...

[SAM/CH ZR-1]

My guess is that the B&B exhaust is worth 20-25hp on a 375hp. car. But that's if you've already got headers. I think mine (see mods below) is close to all you can do with a stock motor, and just bolt-on exhaust, no cats, no resonator, and an X pipe. Overall, it picked up 7mph. in the quarter, for 117mph. Thats over 400hp. at the crank, easy.
Marc's 510hp. package is the very best mod for the car, in my opinion. Because it retains the stock shortblock, which is what makes the ZR-1 so special, and durable.
I've been saving my pennies for a long time to have Marc do the top-end on my car. But I never seem to have an "extra" $10-15K.:rolleyes:

Some years ago I've read a test about performance gain of different aftermarket exhaust systems on a stock engine. The B&B pulled +12 HP. The winner was PowerEffects with +13 HP.

[Bob Eyres]

Some years ago I've read a test about performance gain of different aftermarket exhaust systems on a stock engine. The B&B pulled +12 HP. The winner was PowerEffects with +13 HP.

Possible, but hard to believe, because the PowerEffects system is a 2 3/4" system that necks down to 2 1/2" in places. doesn't it?
It's all about flow. And it's hard to beat 3" B&B's all the way from the headers to the mufflers, with an X pipe instead of a restrictive resonator.
Sound is a whole other issue. And the more free flow you have, generally there is more resonance.

[SAM/CH ZR-1]

Possible, but hard to believe, because the PowerEffects system is a 2 3/4" system that necks down to 2 1/2" in places. doesn't it?
It's all about flow. And it's hard to beat 3" B&B's all the way from the headers to the mufflers, with an X pipe instead of a restrictive resonator.
Sound is a whole other issue. And the more free flow you have, generally there is more resonance.

Yes and No.
The size of a exhaust system including headers depend on the displacement size of a engine. Alot doesn't always bring alot.
All tested exhaust systems had a resonator. For comparison purposes it wouldn't be fair to test a X-pipe against resonators.

Marc Haibeck write on his homepage a 2.5 inch Corsa can outperform a B&B. What is true now?

I have the PowerEffects with headers and catalytic converters in my car and don't want to miss the unique sound note.

[Bob Eyres]

It's true that Corsa is a triumph of sound engineering. At moderate speeds it sounds great, with little resonance. And at full throttle it has an amazing ripping sound, loud as hell. Much like my 3" system with the mufflers pulled. If I ever change exhaust again, it will be to a Corsa.

But despite the pic. on the Haibeck website:

http://www.zr1specialist.com/HAT%20Web/Tech%20Info/corsa%20vs%20b&b.htm

I can't take a picture of a light shining through a Corsa muffler as evidence that overall it flows better than a 3" exhaust, with X pipe and headers. I'd prefer to see a direct dyno comparison. Has anyone done that?

All this begs the question, why not build a 3" muffler with the same design as the Corsa? That might cure some of the hellacious resonance that I suffer. I'd buy it, and try it on my car.

[5ABI VT]

I have the B&B on my 93 but its the newer system with all the baffles. The early systems B&B had coma inducing resonance BUT had more free flowing mufflers. With all their R&D they opted to just weld walls and make their mufflers a maze to reduce resonance. I plan to cut the tops of the mufflers open and cut out the walls. It already resonates like an airplane I figure it couldn't get any worse.

I believe the idea is gasses don't like turns and walls etc. A straight through muffler will flow better than one that has a maze of turns inside. No expert on this stuff so I wont go into too much detail but one way I like to explain to people that seems to be pretty funny is make a driving sound with your mouth and make a boomy sort of sound. Notice you have to restrict the flow to get that sound. That's the B&B to me.

[A1990]

Very interesting following this discussion. I remembered that I had Marc Haibeck perform a test back in 2003.

First Marc writes on 7/17/2003:

You have asked a good question. A few weeks ago I got suspicious after driving a typical Triflow equipped car. I was reminded of the terrible resonance that is associated with the system. I thought that your car was too quiet. I looked at your mufflers and indeed they have the flow restrictor plates.

Here's how we will sort this out. I'm scheduled to dyno test a car with the early version of the Triflow on 28-Jul. I spoke with the owner of the car and he has agreed to let me install your mufflers on his car for a test. We will find out how the two mufflers compare in terms of engine power.


Then after Marc's test on 7/28/2003 he writes:

I ran the muffler test today. We ran it on a 450 hp LT5. I made a run with B&B Triflows that are about four years old. Then I removed the old mufflers and installed your mufflers. It appears that your mufflers allowed about 1 more HP to be produced. In my opinion there is no significant power difference between the old and new style B&B ZR-1 mufflers.

[Bob Eyres]

It seems logical that a 3" system with a Corsa style muffler would be the best of both worlds.
Does someone know why the Corsa has negligible resonance with a straight through pipe?

[5ABI VT]

Corsa uses a specific type of noise canceling I forget the name .. Helmholtz or something ? I can't recall exactly. I believe the pipe isn't straight all the way through the muffler .. There is a gap in the pipe allowing sound waves to get into the muffler etc that cancel out certain frequencies. At least that's what I think I learned over the years lol. With the insulation and matting I added in the trunk recently I have 0 resonance at cruising speeds even with varied load.

Anyhow I've been exploring some custom exhaust ideas .. Some interesting ones for sure and one of them is using other kinds of 3" Corsa system mufflers on the z. On the other hand the one thing preventing me from hitting the send button on paypal is the fact that I don't need the extra flow just yet:neutral:

[Pete]

The 2 1/2" Corsas are ok up to a certain point.

On the B&B's it's not the mufflers that are the restriction it's the resonator.
Replace it with a good 3" X pipe and u will see 15-20 hp gains depends on your mods.

I've tested the Corsa's on a 450 RWHP 350ci LT5 (full length headers no CATS) against a full 3" free flowing, X-pipe,exhaust,the difference was 12-14 rwhp the sound the Corsa made at 7k rpm my ears were ringing for a week OMG.
You know that sound when you hear a Honda with fart mufflers at WOT you look and say what a POS. :)

Here's food for thought c6 ZO6 (430-450rwhp),C6 ZR1 (530-550rwhp) they come with 3" exhaust. If GM can make the same power with 2" or 2 1/2" why would they spend extra money on 3" and save some weight.

Enjoy
Pete

[Paul Workman]

The "Helmholtz" technique is widely used to cancel not only exhaust drone, but also is used on some intake systems for the same reason: cancelling drone (I reference my '05 F150 intake snorkel which has a pair of Helmholtz chambers built into it).

The Helmholtz resonator is a chamber with an opening at one end where air (or exhaust pulses) pass across it, setting up an oscillation - not unlike a pipe organ or a flute.

The difference is the Helmholtz chamber - unlike the pipe organ/flute - has no second opening: it is a closed chamber.

The Corsa Helmholtz (resonator) chamber is formed by a length of jacket surrounding the exhaust pipe; a tube within a tube. (Exhaust sound) pulses pass over open slots at the input end of the resonator and some of the energy passed into the (resonator's) chamber.

Like ripples in a bathtub, the sound waves (energy) travel the length of the chamber and bounce off the closed end, returning to the slots where they entered. However, the length of the resonator, is such that certain pulses (frequencies) arrive out of phase - opposite to - the incoming pulses, i.e., (-) (+) = 0, and the pulses (sound) cancel one-another.

However, the length of the "resonator" chamber effectively results in cancellation of only a narrow band of frequencies. Therefore, to cancel other frequencies, additional resonators of different lengths are used. The Corsa mufflers too are Helmholtz resonators of other length(s) to effectively cover a wider range of frequency cancellations.

The frequencies generated by a car's engine vary with rpm and number of cylinders, etc. In addition, there are harmonic frequencies (x2, x3, etc) generated by the engine and within the resonating chambers themselves. Practicality limits the number of counter-acting resonators that can be installed in a typical exhaust system. However, the amplitude (strength) of these harmonics are considerably lower in strength, especially true of the higher frequency tones. (These higher pitched frequencies, albeit lower in volume than low frequencies, are not fully cancelled; a compromise in the Corsa design due to those practical limitations. These frequencies produce the higher pitched sounds which some find more objectionable than others: "tinny" to some ears - like mine.)

IDK if this explanation helps or hinders, or if my prose did their intended job, but I find such engineering "tricks" to be fascinating.:cheers:

[WARP TEN]

The "Helmholtz" technique is widely used to cancel not only exhaust drone, but also is used on some intake systems for the same reason: cancelling drone (I reference my '05 F150 intake snorkel which has a pair of Helmholtz chambers built into it).

The Helmholtz resonator is a chamber with an opening at one end where air (or exhaust pulses) pass across it, setting up an oscillation - not unlike a pipe organ or a flute.

The difference is the Helmholtz chamber - unlike the pipe organ/flute - has no second opening: it is a closed chamber.

The Corsa Helmholtz (resonator) chamber is formed by a length of jacket surrounding the exhaust pipe; a tube within a tube. (Exhaust sound) pulses pass over open slots at the input end of the resonator and some of the energy passed into the (resonator's) chamber.

Like ripples in a bathtub, the sound waves (energy) travel the length of the chamber and bounce off the closed end, returning to the slots where they entered. However, the length of the resonator, is such that certain pulses (frequencies) arrive out of phase - opposite to - the incoming pulses, i.e., (-) (+) = 0, and the pulses (sound) cancel one-another.

However, the length of the "resonator" chamber effectively results in cancellation of only a narrow band of frequencies. Therefore, to cancel other frequencies, additional resonators of different lengths are used. The Corsa mufflers too are Helmholtz resonators of other length(s) to effectively cover a wider range of frequency cancellations.

The frequencies generated by a car's engine vary with rpm and number of cylinders, etc. In addition, there are harmonic frequencies (x2, x3, etc) generated by the engine and within the resonating chambers themselves. Practicality limits the number of counter-acting resonators that can be installed in a typical exhaust system. However, the amplitude (strength) of these harmonics are considerably lower in strength, especially true of the higher frequency tones. (These higher pitched frequencies, albeit lower in volume than low frequencies, are not fully cancelled; a compromise in the Corsa design due to those practical limitations. These frequencies produce the higher pitched sounds which some find more objectionable than others: "tinny" to some ears - like mine.)

IDK if this explanation helps or hinders, or if my prose did their intended job, but I find such engineering "tricks" to be fascinating.:cheers:
Paul is dead on with his explanation. Corsa calls its Helmholtz resonators "Quarter Wave Tuners". In the mid 90s, when I was testing exhaust systems on my 1993 ZR-1 and I had a Power Effects with incredible resonance, I gave the car to a friend who was #2 engineering guy at Outboard Marine. He had his acoustics engineer wire the car to determine what was causing the intense resonance at a couple of rpm points. They concluded that it was indeed engine-caused resonance (as opposed to, say, cavity resonance caused by the enclosed cabin) with significant spikes at two rpm points, about 1800 and 3400 rpms. The 1800 rpm point corresponds to about 70 mph with a stock ratio axle and under any load was quite intense. On the ZR-1 with a stock (or Corsa) exhaust system the frequency at one rpm point is handled by the center resonator and the other by the mufflers; I don't recall which is which. I can't find my original graphs and correspondence but I know I gave copies to Marc Haibeck and he has them buried somewhere in his archives. --Bob

[Pete]

4508


If your looking for sound the above does not matter.
If your looking for HP 2 1/2" isn't enough for 500HP.

Hope this worked
Pete

[Fully Vetted]

The 2 1/2" Corsas are ok up to a certain point.

On the B&B's it's not the mufflers that are the restriction it's the resonator.
Replace it with a good 3" X pipe and u will see 15-20 hp gains depends on your mods.

I've tested the Corsa's on a 450 RWHP 350ci LT5 (full length headers no CATS) against a full 3" free flowing, X-pipe,exhaust,the difference was 12-14 rwhp the sound the Corsa made at 7k rpm my ears were ringing for a week OMG.
You know that sound when you hear a Honda with fart mufflers at WOT you look and say what a POS. :)

Here's food for thought c6 ZO6 (430-450rwhp),C6 ZR1 (530-550rwhp) they come with 3" exhaust. If GM can make the same power with 2" or 2 1/2" why would they spend extra money on 3" and save some weight.

Enjoy
Pete

Yeah, it always felt like I lost just a bit of power when I went with the Corsa set up and you're numbers prove what I felt.

But I do like the sound. And there aren't many people looking around for Honda's when I cruise through.

[Bob Eyres]

I've tested the Corsa's on a 450 RWHP 350ci LT5 (full length headers no CATS) against a full 3" free flowing, X-pipe, exhaust, the difference was 12-14 rwhp the sound the Corsa made at 7k rpm my ears were ringing for a week OMG.
Pete

I'm not clear on that. You tested a 350c.i. LT5 with headers, no cats, 3" X pipe, and 3" exhaust. What kind? B&B? You don't say which one gave 12-14 more rwhp.

There's two ways to evaluate the exhaust. One is, "is it the sound i like?" resonance, and the other problems included.
The other is, "Does it flow better and get more HP?
The only issue I really care about is the actual performance. I'll live with the sound.
But, if you've got a system that provides the most power, and it sounds great, all the better.
So, does the Corsa pull the best dyno numbers on a 350? If so, I'll go with that. Because I know that Corsa has the best reputation for cutting down on the resonance.
Right now, the B&B (old style) I have with 3" X pipe gets the best hp. numbers that I've gotten yet. I'll stick with it until someone proves otherwise.

[XfireZ51]

Let's put it this way. Pete is not a fan of the Corsa principally because it's not a 3" exhaust, which translates into power loss. He offered the example above documenting a 12-14rwhp delta between a 3" exhaust and the Corsa.

[Fully Vetted]

I put 430 down to the wheels before I put on the Corsa. I haven't redynoed but if I lost 12hp I'm ok with that. I was damn near deaf on my first trip to BG with my old exhaust and I couldn't even use the radio because of the drone. Everything is peachy with my Corsa and I can still keep up with most things on the road so it works. For me, anyway.

[Paul Workman]

Lol. Yeah the car is legit. It's got what looks like an LT5 engine, engine valet key, ride control switch and the tail is wider than the standard C4. Obviously more horsepower and rumble than my standard 95. Maybe the exhaust place told him that.

I had the Borla cat-back on my otherwise stock 90 ZR-1. Comparing my dyno results to other stock LT5s, I'd have to contest that HP claim, on that (dyno) basis alone.

I didn't loose any performance vs. stock numbers compared to results others have posted. But, I sure as hell didn't gain any 50-60 hp performance boost as result of the Borla!:thumbsdo:

[SAM/CH ZR-1]

Here's food for thought c6 ZO6 (430-450rwhp),C6 ZR1 (530-550rwhp) they come with 3" exhaust. If GM can make the same power with 2" or 2 1/2" why would they spend extra money on 3" and save some weight.

Enjoy
Pete

Because the C6 Z06 has a 427 displacement and the C6 ZR1 a compressor. That requires a bigger exhaust system.

I did the experience that 350 cui engines loose some low end torque with headers and a open 3 Inch exhausts.

Sam

[Bob Eyres]

I had the Borla cat-back on my otherwise stock 90 ZR-1. Comparing my dyno results to other stock LT5s, I'd have to contest that HP claim, on that (dyno) basis alone.

I didn't loose any performance vs. stock numbers compared to results others have posted. But, I sure as hell didn't gain any 50-60 hp performance boost as result of the Borla!:thumbsdo:

Borla, although one of the sweetest sounding aftermarket exhausts for the LT5, is one of the worst if you're looking for performance improvement.
I installed the Borla "so called" 2 3/4" system in 1995. Sounded great, but no real improvement.
It wasn't until I went with the B&B, with headers and no cats that the car really woke up.


Light, single mass flywheel, and 3" inch exhaust. They sure do help the stock LT5,.....but the F:censored:ing PAIN..:eek:

[XfireZ51]

Because the C6 Z06 has a 427 displacement and the C6 ZR1 a compressor. That requires a bigger exhaust system.

I did the experience that 350 cui engines loose some low end torque with headers and a open 3 Inch exhausts.

Sam

Sam,

Did you update the tune to optimize for the difference in backpressure?