Most power thru a single 3" catback?
Most power thru a single 3" catback? Move if not allowed, but I figured I'd get more of the answers I'm looking for here.
Anyone here making 600rwhp or more thru a single 3" catback all the way to the bumper?
Or any before and after dyno or track times? What did you gain or lose?
Anyone here making 600rwhp or more thru a single 3" catback all the way to the bumper?
Or any before and after dyno or track times? What did you gain or lose?
I've never seen it done naturally aspirated, only with power adder (nitrous, boosted). I have seen 600 RWHP n/a with 3.5" single over the axle. Muffler is super duper important with a single exhaust.
I make 680rwhp (Procharged) now thru a 4" over the axle that Y out into dual 3" but I have this insanely stupid idea of throwing stock exhaust manifolds back on and a 3" magnaflow catback. 50% of me loves the agressively loud 4" exhaust and nasty big red bypass.....the other 50% wants to shut the stupid bypass up and wants oem level of quietness of stock manifolds and smooth enjoyable ride.
Hell, even if that knocked 80rwhp off, 600 in a quiet smooth car would be plenty fun for me and how I drive.
I do my own tuning so I can swap them back whenever I want
Hell, even if that knocked 80rwhp off, 600 in a quiet smooth car would be plenty fun for me and how I drive.
I do my own tuning so I can swap them back whenever I want
I did exactly this on my last turbo 4th gen camaro.
Single 3" exhaust out the back to the biggest magnaflow muffler I could fit.
Then I did an electric cutout under the driver floor board, far enough from the turbo so as not to impact its longevity which I think worked since it gave me trouble free service for almost four years.
That combo made the car quite pleasant to cruise in, still sounded good and with the cutout open ripped and made all the turbo noises laying down 689whp.
Would definitely recommend for anyone wanting the best of both worlds.
Single 3" exhaust out the back to the biggest magnaflow muffler I could fit.
Then I did an electric cutout under the driver floor board, far enough from the turbo so as not to impact its longevity which I think worked since it gave me trouble free service for almost four years.
That combo made the car quite pleasant to cruise in, still sounded good and with the cutout open ripped and made all the turbo noises laying down 689whp.
Would definitely recommend for anyone wanting the best of both worlds.
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Verdad Gallardo Wow, that's impressive and hard to imagine because the difference I felt between open and closed cutout was huge.
The turbo spooled faster and it hit way harder, if I had to guess I'd say it had to be worth at least 50-60 hp, maybe more.
Not sure how you'd get around the loud bypass but you can certainly make the exhaust quieter and add a cutout.
The bigger the pipe, the more noise it makes.
I had dual 3.5" pipes dumped at the axle on my old 70 camaro with an 11.5:1 bbc with dynatec mufflers, talk about loud, fuq oh dear lol.
The turbo spooled faster and it hit way harder, if I had to guess I'd say it had to be worth at least 50-60 hp, maybe more.
Not sure how you'd get around the loud bypass but you can certainly make the exhaust quieter and add a cutout.
The bigger the pipe, the more noise it makes.
I had dual 3.5" pipes dumped at the axle on my old 70 camaro with an 11.5:1 bbc with dynatec mufflers, talk about loud, fuq oh dear lol.
Wow, that's impressive and hard to imagine because the difference I felt between open and closed cutout was huge.
The turbo spooled faster and it hit way harder, if I had to guess I'd say it had to be worth at least 50-60 hp, maybe more.
Not sure how you'd get around the loud bypass but you can certainly make the exhaust quieter and add a cutout.
The bigger the pipe, the more noise it makes.
I had dual 3.5" pipes dumped at the axle on my old 70 camaro with an 11.5:1 bbc with dynatec mufflers, talk about loud, fuq oh dear lol.
The turbo spooled faster and it hit way harder, if I had to guess I'd say it had to be worth at least 50-60 hp, maybe more.
Not sure how you'd get around the loud bypass but you can certainly make the exhaust quieter and add a cutout.
The bigger the pipe, the more noise it makes.
I had dual 3.5" pipes dumped at the axle on my old 70 camaro with an 11.5:1 bbc with dynatec mufflers, talk about loud, fuq oh dear lol.
Wow, that's impressive and hard to imagine because the difference I felt between open and closed cutout was huge.
The turbo spooled faster and it hit way harder, if I had to guess I'd say it had to be worth at least 50-60 hp, maybe more.
Not sure how you'd get around the loud bypass but you can certainly make the exhaust quieter and add a cutout.
The bigger the pipe, the more noise it makes.
I had dual 3.5" pipes dumped at the axle on my old 70 camaro with an 11.5:1 bbc with dynatec mufflers, talk about loud, fuq oh dear lol.
The turbo spooled faster and it hit way harder, if I had to guess I'd say it had to be worth at least 50-60 hp, maybe more.
Not sure how you'd get around the loud bypass but you can certainly make the exhaust quieter and add a cutout.
The bigger the pipe, the more noise it makes.
I had dual 3.5" pipes dumped at the axle on my old 70 camaro with an 11.5:1 bbc with dynatec mufflers, talk about loud, fuq oh dear lol.
Bigger certainly works better, but it’ll work with a smaller engine just gotta lean on it. I go back and forth between mufflers and not, since they recently repealed our exhaust noise ordinance I yoked mine off and did front dumps. Losing the weight helped make up for the absurd intercooler I added.
I love it sooo much.
What's funny though is the turbo sucking in air when in the throttle becomes louder then the exhaust.
I think mine were the 10" or 12" model in 3.5" so you know the pain lmao.
With a supercharger, you can squeeze quite a bit of power through a relatively restrictive exhaust, it just moves the blower boost up some. Not so much with a turbo car - it makes a notable difference.
I've played with the exhaust some on my car on the dyno (cut out, no cut out, better exhaust, worse, etc...). After the header converger, any of the changes I made just moved the boost around a smidge with a small impact on power. All of the changes (stock exhaust, larger Y, flowmaster 80, stock muffler, cut out open/closed), put out around 700 HP (+/- a little) and just moved the boost around a few pounds.
So, now I run a quiet muffler, and just deal with the slightly higher boost. A little over 700 RWHP on a 3" catback through a stock muffler with the D1 at ~15 psig.
I've played with the exhaust some on my car on the dyno (cut out, no cut out, better exhaust, worse, etc...). After the header converger, any of the changes I made just moved the boost around a smidge with a small impact on power. All of the changes (stock exhaust, larger Y, flowmaster 80, stock muffler, cut out open/closed), put out around 700 HP (+/- a little) and just moved the boost around a few pounds.
So, now I run a quiet muffler, and just deal with the slightly higher boost. A little over 700 RWHP on a 3" catback through a stock muffler with the D1 at ~15 psig.
With a supercharger, you can squeeze quite a bit of power through a relatively restrictive exhaust, it just moves the blower boost up some. Not so much with a turbo car - it makes a notable difference.
I've played with the exhaust some on my car on the dyno (cut out, no cut out, better exhaust, worse, etc...). After the header converger, any of the changes I made just moved the boost around a smidge with a small impact on power. All of the changes (stock exhaust, larger Y, flowmaster 80, stock muffler, cut out open/closed), put out around 700 HP (+/- a little) and just moved the boost around a few pounds.
So, now I run a quiet muffler, and just deal with the slightly higher boost. A little over 700 RWHP on a 3" catback through a stock muffler with the D1 at ~15 psig.
I've played with the exhaust some on my car on the dyno (cut out, no cut out, better exhaust, worse, etc...). After the header converger, any of the changes I made just moved the boost around a smidge with a small impact on power. All of the changes (stock exhaust, larger Y, flowmaster 80, stock muffler, cut out open/closed), put out around 700 HP (+/- a little) and just moved the boost around a few pounds.
So, now I run a quiet muffler, and just deal with the slightly higher boost. A little over 700 RWHP on a 3" catback through a stock muffler with the D1 at ~15 psig.
I think it is because the engine speed sets the blower speed, and the blower speed sets the airflow of the setup and the airflow basically sets the HP (assuming constant a/f ratio). There are some changes in parasitic losses through all of this, but apparently, not pronounced enough to move things around that much.
With a supercharger, you can squeeze quite a bit of power through a relatively restrictive exhaust, it just moves the blower boost up some. Not so much with a turbo car - it makes a notable difference.
I've played with the exhaust some on my car on the dyno (cut out, no cut out, better exhaust, worse, etc...). After the header converger, any of the changes I made just moved the boost around a smidge with a small impact on power. All of the changes (stock exhaust, larger Y, flowmaster 80, stock muffler, cut out open/closed), put out around 700 HP (+/- a little) and just moved the boost around a few pounds.
So, now I run a quiet muffler, and just deal with the slightly higher boost. A little over 700 RWHP on a 3" catback through a stock muffler with the D1 at ~15 psig.
I've played with the exhaust some on my car on the dyno (cut out, no cut out, better exhaust, worse, etc...). After the header converger, any of the changes I made just moved the boost around a smidge with a small impact on power. All of the changes (stock exhaust, larger Y, flowmaster 80, stock muffler, cut out open/closed), put out around 700 HP (+/- a little) and just moved the boost around a few pounds.
So, now I run a quiet muffler, and just deal with the slightly higher boost. A little over 700 RWHP on a 3" catback through a stock muffler with the D1 at ~15 psig.
I'm running a D1SC at 15psi also.
I assume your running headers. So single 3" thru a stock muffler and you make 700rwhp.
What was your experience with the Stock manifolds and the D1SC?
I didn't run the stock headers, but I ran JBA shorties with the blower and compared to LT's.
All of the exhaust changes I made down to the header collector (LT's headers, high-velocity merge), brought the boost down a little and picked up noticeable HP. Once I got further back in the exhaust from the header merge, the exhaust changes just moved the boost around and didn't really do much for HP: couple differ Y setups, couple different muffles, cutout open/closed, etc...
So, I think good LT headers and a good header merge are important and will add HP to the setup - after that, I think the other exhaust options that we have available for these cars are in the noise and just moving the boost around on a SC setup.
All of the exhaust changes I made down to the header collector (LT's headers, high-velocity merge), brought the boost down a little and picked up noticeable HP. Once I got further back in the exhaust from the header merge, the exhaust changes just moved the boost around and didn't really do much for HP: couple differ Y setups, couple different muffles, cutout open/closed, etc...
So, I think good LT headers and a good header merge are important and will add HP to the setup - after that, I think the other exhaust options that we have available for these cars are in the noise and just moving the boost around on a SC setup.
TECH Fanatic
Joined: Jun 2003
Posts: 1,869
Likes: 99
I make 680rwhp (Procharged) now thru a 4" over the axle that Y out into dual 3" but I have this insanely stupid idea of throwing stock exhaust manifolds back on and a 3" magnaflow catback. 50% of me loves the agressively loud 4" exhaust and nasty big red bypass.....the other 50% wants to shut the stupid bypass up and wants oem level of quietness of stock manifolds and smooth enjoyable ride.
Hell, even if that knocked 80rwhp off, 600 in a quiet smooth car would be plenty fun for me and how I drive.
I do my own tuning so I can swap them back whenever I want
Hell, even if that knocked 80rwhp off, 600 in a quiet smooth car would be plenty fun for me and how I drive.
I do my own tuning so I can swap them back whenever I want
https://shop.brutespeed.com/ATI-3FAS...-3FASS-003.htm
Current engine setup:
TSP LQ9 370 Iron Block. ARH 1 7/8 headers with ARH catted j pipe merged to single 3 inch pipe back to Magnaflow catback. ATI D1SC at 8 psi - 600 rwhp.
These two Magnaflow straight thru shorties aft of the Magnaflow muffler got rid of noisy annoying rasp.
Last edited by dlandsvZ28; Jun 30, 2021 at 10:57 AM. Reason: edit content
I agree on the extremely loud Big Red ATI race valve. I removed it and replaced with this one in link below. Can hardly hear it now. I thought I might have to add a hose to it and direct air backwards but didn't have it. Is quiet enough as is. Almost as quiet as the black bypass included with a D1SC kit.
https://shop.brutespeed.com/ATI-3FAS...-3FASS-003.htm
Current engine setup:
TSP LQ9 370 Iron Block. ARH 1 7/8 headers with ARH catted j pipe merged to single 3 inch pipe back to Magnaflow catback. ATI D1SC at 8 psi - 600 rwhp.
https://www.flickr.com/photos/183593...7623345499537/
These two Magnaflow straight thru shorties aft of the Magnaflow muffler got rid of noisy annoying rasp.
https://www.flickr.com/photos/183593...7623345499537/
https://shop.brutespeed.com/ATI-3FAS...-3FASS-003.htm
Current engine setup:
TSP LQ9 370 Iron Block. ARH 1 7/8 headers with ARH catted j pipe merged to single 3 inch pipe back to Magnaflow catback. ATI D1SC at 8 psi - 600 rwhp.
https://www.flickr.com/photos/183593...7623345499537/
These two Magnaflow straight thru shorties aft of the Magnaflow muffler got rid of noisy annoying rasp.
https://www.flickr.com/photos/183593...7623345499537/
I was wondering if adding the enclosed bypass would be quiet by itself or if a hose would be needed.
Do you have any videos of your car? I'd like to hear what that sounds like.
just wondering, with a forged 370, why only run 8 psi?
TECH Fanatic
Joined: Jun 2003
Posts: 1,869
Likes: 99
Since then have replaced 7.65 pulley with a CBR 8.65 crank pulley, moved idler pulley on Aster Bracket, and replaced Mishimoto 26 X 12 X 4 inch FMIC with the Camaro Procharger 26 X 12 X 4.5 inch intercooler (see pic below). Also removed two silicone connectors in the charge pipes with welded connections for better flow and less restriction.
I have no doubt that the ATI intercooler will add more boost and is more efficient than the Mishimoto intercooler. The larger crank pulley should reduce belt slip and also increase blower rpm and boost and still be under max D1SC impeller rpm with the 3.9 pulley. Still running the Gates green belt with plans to switch to the Gates RPM blower belt when I finalize pulley size and belt length with the green belt.
Will be interesting to see the results. I'm thinking boost will be somewhere between 8 to 12 lbs.
Goes on the dyno next week. Will report results for the OP when running with cats, a single I pipe and Magnaflow catback. Will get some videos while on the dyno.
Dyno operator and tuner is still the same (Dynojet Eddy Current Load Control two-wheel dynamometer - similar to a Mustang Dyno). So will be an apples to apples comparison when dynoed previously.
ATI Procharger intercooler with AC condenser relocated off the face of the radiator (still run AC and was getting 34 degree at each dash outlet last week with ambient temps at 102 F).
Note: I'm not looking for max rwhp - another 50 to 75 RWHP is enough. Car drives nice with a Yank 3450 blower converter, Performabilt level III 4l60E tranny with 3.23 gears.
Last edited by dlandsvZ28; Jun 30, 2021 at 11:18 AM. Reason: edit content