Boost control for added back pressure on turbo
The last vehicle we did this same test to went from a single 3" to a single 4" and was making right around 700 rwhp on a 5.7L with a 7675. It gained 40 rwhp, but boost also jumped up 1.5 psi or so and adjusting it back down to it's original boost level it made with 10 horsepower. The turbo wasn't maxed out, it's not a small displacement engine, obviously the exhaust behind the turbo wasn't as much of a restriction to begin with. But the thing is we've been done this test more times than I can count, and the vast majority of the combos that didn't have maxed out turbos didn't pick up much of anything by going bigger with boost held constant. Sure it dropped wastegate duty cycle, it spooled a bit faster, but that was about it. I'm not saying EVERY combo is like this, but most of them don't care if it's not maxed out already.
Holy ****, a completely irrelevant advertisement from a magazine! However I would completely expect a sooopra with a small turbo to gain power with bigger exhaust, but we aren't talking about one of those here.
The last vehicle we did this same test to went from a single 3" to a single 4" and was making right around 700 rwhp on a 5.7L with a 7675. It gained 40 rwhp, but boost also jumped up 1.5 psi or so and adjusting it back down to it's original boost level it made with 10 horsepower. The turbo wasn't maxed out, it's not a small displacement engine, obviously the exhaust behind the turbo wasn't as much of a restriction to begin with. But the thing is we've been done this test more times than I can count, and the vast majority of the combos that didn't have maxed out turbos didn't pick up much of anything by going bigger with boost held constant. Sure it dropped wastegate duty cycle, it spooled a bit faster, but that was about it. I'm not saying EVERY combo is like this, but most of them don't care if it's not maxed out already.
The last vehicle we did this same test to went from a single 3" to a single 4" and was making right around 700 rwhp on a 5.7L with a 7675. It gained 40 rwhp, but boost also jumped up 1.5 psi or so and adjusting it back down to it's original boost level it made with 10 horsepower. The turbo wasn't maxed out, it's not a small displacement engine, obviously the exhaust behind the turbo wasn't as much of a restriction to begin with. But the thing is we've been done this test more times than I can count, and the vast majority of the combos that didn't have maxed out turbos didn't pick up much of anything by going bigger with boost held constant. Sure it dropped wastegate duty cycle, it spooled a bit faster, but that was about it. I'm not saying EVERY combo is like this, but most of them don't care if it's not maxed out already.
Holy ****, a completely irrelevant advertisement from a magazine! However I would completely expect a sooopra with a small turbo to gain power with bigger exhaust, but we aren't talking about one of those here.
The last vehicle we did this same test to went from a single 3" to a single 4" and was making right around 700 rwhp on a 5.7L with a 7675. It gained 40 rwhp, but boost also jumped up 1.5 psi or so and adjusting it back down to it's original boost level it made with 10 horsepower. The turbo wasn't maxed out, it's not a small displacement engine, obviously the exhaust behind the turbo wasn't as much of a restriction to begin with. But the thing is we've been done this test more times than I can count, and the vast majority of the combos that didn't have maxed out turbos didn't pick up much of anything by going bigger with boost held constant. Sure it dropped wastegate duty cycle, it spooled a bit faster, but that was about it. I'm not saying EVERY combo is like this, but most of them don't care if it's not maxed out already.
The last vehicle we did this same test to went from a single 3" to a single 4" and was making right around 700 rwhp on a 5.7L with a 7675. It gained 40 rwhp, but boost also jumped up 1.5 psi or so and adjusting it back down to it's original boost level it made with 10 horsepower. The turbo wasn't maxed out, it's not a small displacement engine, obviously the exhaust behind the turbo wasn't as much of a restriction to begin with. But the thing is we've been done this test more times than I can count, and the vast majority of the combos that didn't have maxed out turbos didn't pick up much of anything by going bigger with boost held constant. Sure it dropped wastegate duty cycle, it spooled a bit faster, but that was about it. I'm not saying EVERY combo is like this, but most of them don't care if it's not maxed out already.
o and btw, you are saying that a SMALL turbo and a Smaller engine would be expected to pick up more power than a larger turbo and engine? I’m having a hard time wrapping my head around that *** backwards assumption. Lol. Just lol.
Yes, smaller engines/turbos love pressure ratios but larger engines/turbos don't have that. I can tell this is hard for you...
My 2 experiences-
383 LS, 76GTS, 8 psi. 3 inch downpipe to 3.5" over axle exhaust. Picked up 30WHP through a 9 inch at the same boost level, Zero other changes and back to back pulls.
LS6 7875 rear mount. 3 inch downpipe with a turbo style muffler. Total of about 4 feet. With the cutout closed the car will maybe make 5-7 psi and is a DOG. Open the cutout right off the downpipe and the car will make 16 psi and spin 315 wide tires from a roll on in third gear at 70-80mph.
383 LS, 76GTS, 8 psi. 3 inch downpipe to 3.5" over axle exhaust. Picked up 30WHP through a 9 inch at the same boost level, Zero other changes and back to back pulls.
LS6 7875 rear mount. 3 inch downpipe with a turbo style muffler. Total of about 4 feet. With the cutout closed the car will maybe make 5-7 psi and is a DOG. Open the cutout right off the downpipe and the car will make 16 psi and spin 315 wide tires from a roll on in third gear at 70-80mph.
My 2 experiences-
383 LS, 76GTS, 8 psi. 3 inch downpipe to 3.5" over axle exhaust. Picked up 30WHP through a 9 inch at the same boost level, Zero other changes and back to back pulls.
LS6 7875 rear mount. 3 inch downpipe with a turbo style muffler. Total of about 4 feet. With the cutout closed the car will maybe make 5-7 psi and is a DOG. Open the cutout right off the downpipe and the car will make 16 psi and spin 315 wide tires from a roll on in third gear at 70-80mph.
383 LS, 76GTS, 8 psi. 3 inch downpipe to 3.5" over axle exhaust. Picked up 30WHP through a 9 inch at the same boost level, Zero other changes and back to back pulls.
LS6 7875 rear mount. 3 inch downpipe with a turbo style muffler. Total of about 4 feet. With the cutout closed the car will maybe make 5-7 psi and is a DOG. Open the cutout right off the downpipe and the car will make 16 psi and spin 315 wide tires from a roll on in third gear at 70-80mph.
That is a crazy differnce, I was super impressed with the car with the downpipe open, with the exhaust I find it slow now, but I made 12psi max the other day and 10 last time i had it out. Likely going 4in bumper exit and go to the 78/75 ball bearing 4in exit. We all know the best turbo exhaust in no exhaust
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You went from "I want a quiet cruiser" to "f__k it let it be loud" real fast lol.
I love my fender exit btw, it makes all the turbo noises and spools up pretty quickly and revs to the moon.
I realize the 75mm turbine will be what holds you back to a degree, but I started with a 7875 too and now have an S484.
I love my fender exit btw, it makes all the turbo noises and spools up pretty quickly and revs to the moon.
I realize the 75mm turbine will be what holds you back to a degree, but I started with a 7875 too and now have an S484.
You went from "I want a quiet cruiser" to "f__k it let it be loud" real fast lol.
I love my fender exit btw, it makes all the turbo noises and spools up pretty quickly and revs to the moon.
I realize the 75mm turbine will be what holds you back to a degree, but I started with a 7875 too and now have an S484.
I love my fender exit btw, it makes all the turbo noises and spools up pretty quickly and revs to the moon.
I realize the 75mm turbine will be what holds you back to a degree, but I started with a 7875 too and now have an S484.