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Old 09-19-2009, 08:31 PM   #1
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Default The sequential(compound) turbo era?

First we had tiny turbos... Then medium turbos, and we pretty much went from medium to ridiculous in about a year. Now we're getting near the pressure ratio limit that ridiculous can provide.

Its kind of been inching up little by little, and I know I've worked with several guys in the 400-500whp range who are already seeing some pretty extreme intake temps, but past 500 I would imagine almost any turbo you choose is going to be at the extreme limit of efficiency because of the pressure ratio. I guess the question is, whats going to happen first, motors not taking more, or sequential turbo installs? If its the latter then maybe a sequential mounted GT2876 blowing through a GT3582R? That would give you 40psi+ pressure capacity, with airflow capacity in the 600whp+ range. Thoughts?

General, open ended, time wasting thread.
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Old 09-19-2009, 08:34 PM   #2
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Wasn't there a thread not too long ago featuring a compound (I think that's what you meant) turbo setup on an SC300?

Edit: Found it - https://www.miataturbo.net/forum/t37439/
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Old 09-19-2009, 08:37 PM   #3
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A twin, or single turbo sc300 is my dream daily driver. With that, my jeep, my miata, and maybe a TL1000R what else could I need. Oh a trailer.
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Old 09-19-2009, 08:55 PM   #4
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I think that small sequential turbos on a super low compression engine could make for an awesome setup, at the cost of complexity of course.
Ive been wanting to do just such a setup on a SOHC D-series honda with suzuki vitara pistons (~7.5:1 compression) for some time now
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Old 09-19-2009, 09:22 PM   #5
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A bunch of subaru guys are certainly giving compound boost a shot:



Mercedes AMG twin screw supercharger at 16psi with gt40r turbo at 30psi = god damn
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Old 09-19-2009, 09:22 PM   #6
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*edit: stupid double post
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Old 09-19-2009, 09:29 PM   #7
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I wouldn't mind having a mp62 and a gt3076r on my little 1.6....would be one helluva ride.
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Old 09-20-2009, 12:25 PM   #8
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Quote:
Originally Posted by TravisR View Post
First we had tiny turbos... Then medium turbos, and we pretty much went from medium to ridiculous in about a year. Now we're getting near the pressure ratio limit that ridiculous can provide.

Its kind of been inching up little by little, and I know I've worked with several guys in the 400-500whp range who are already seeing some pretty extreme intake temps, but past 500 I would imagine almost any turbo you choose is going to be at the extreme limit of efficiency because of the pressure ratio. I guess the question is, whats going to happen first, motors not taking more, or sequential turbo installs? If its the latter then maybe a sequential mounted GT2876 blowing through a GT3582R? That would give you 40psi+ pressure capacity, with airflow capacity in the 600whp+ range. Thoughts?

General, open ended, time wasting thread.
I'd build it if someone wanted to fund it just cause it sounds like lots of fun. I'm still deciding between a V8 or sequential TT's, but not in the compound sense cause mine's a stock block street car (small one being depowered when large one starts).
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Old 09-20-2009, 01:23 PM   #9
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I think the number of extreme turbo builds will be dropping with the rise in availability and affordability of V8 swap parts. Why go through the expense and complexity of retaining small cubes when you can just go to big cubes while simultaneously removing the weak links (trans and diff)? Torque curve on the LS3 is none too shabby.
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Old 09-20-2009, 11:15 PM   #10
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Quote:
Originally Posted by Ben View Post
I think the number of extreme turbo builds will be dropping with the rise in availability and affordability of V8 swap parts. Why go through the expense and complexity of retaining small cubes when you can just go to big cubes while simultaneously removing the weak links (trans and diff)? Torque curve on the LS3 is none too shabby.
Yeah, this is the main reason why I'm probably going to go with the ford v8 based swap (I say "based" cause I don't think I'd use a single ford part). To build a fancy sequential setup, plus some sort of bottom end for the BP, would probably cost about what a trick V8 would cost to build+drivetrain. I dunno.
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Old 09-21-2009, 12:29 AM   #11
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I can see the argument for the V8 at that point pretty well. Katech Engine Development - Street Performance scroll down to the LS7 air attack motor. 750whp and 685tq. I think that would do ok?

Still though, if your going over 500 with the Miata, I don't think your going to make it without sequential. You'd be at 35-39psi I think. I imagine we'll see one... eventually.
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Old 09-21-2009, 12:32 AM   #12
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..and? You ever seen Supra turbos? 42R, 45R, 47R, and possibly some larger stuff. 40+psi and capacity to WELL over a thousand horsepower.
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Old 09-21-2009, 12:43 AM   #13
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I just looked it up. It does look like the larger frames tolerate more. 40r does about 35psi, but the efficiency is really low. The 42r does a bit better, but still wouldn't expect over 40psi with any efficiency. It actually looks like you'd be in the 60's as far as efficency. Mise well bolt a supercharger on. The problem is the capacity. I don't know if you could spool a 40r with a 1.8L. Its a 700hp turbo, and the 42r is worse with being even larger. I don't know how you would judge sequential turbo spool. I would imagine you would have a gate to direct flow through one, then then both when you hit the pressure limit, but am unfamiliar with how the pros do it.
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Old 09-21-2009, 12:58 AM   #14
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Quote:
Originally Posted by TurboTim View Post
Yeah, this is the main reason why I'm probably going to go with the ford v8 based swap (I say "based" cause I don't think I'd use a single ford part). To build a fancy sequential setup, plus some sort of bottom end for the BP, would probably cost about what a trick V8 would cost to build+drivetrain. I dunno.
I'm with you there. My passion is being slowly directed to a v8 swap, versus building my motor for more go-fast air.
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Old 09-21-2009, 01:03 AM   #15
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It wouldnt be that hard to run a coldside supercharger after a turbo would it? The supercharger would give you a large boost in pressures while still allowing the single turbo to use all of the exhaust pressure.

Just my $.02
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Old 09-21-2009, 01:27 AM   #16
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Iono to me going into the 400 whp range we leave most of our street aspirations out of the picture, i predict we will see more WI to increase effeciency at the higher boost lvls and a whole lot more nitrous. To hit that **** right though we would be getting into the realm of fueling wich way outpaces a single walboro 255 so that means a dual pump mod or bigger pump retrofit. But hell the 600 whp miata ran 10's, after being tubbed etc, its just plain silly.
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Old 09-21-2009, 09:06 AM   #17
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Quote:
Originally Posted by TravisR View Post
I can see the argument for the V8 at that point pretty well. Katech Engine Development - Street Performance scroll down to the LS7 air attack motor. 750whp and 685tq. I think that would do ok?

Still though, if your going over 500 with the Miata, I don't think your going to make it without sequential. You'd be at 35-39psi I think. I imagine we'll see one... eventually.
Hmm "upgraded valvetrain" I wonder what that means...

Valvetrain never gets any respect.
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Old 09-21-2009, 12:19 PM   #18
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Haha, I just popped apart the valvetrain on a 4.0L ranger. Pushrods looked like mushrooms at the top. OHV=Junk. I love valvetrains, I've never had a single valve train related failure that wasn't from the timing chain/belt. Even when completely mangled it only makes a ticking sound.
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Old 09-21-2009, 02:07 PM   #19
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Travis,
To make a giant turbo spool on a 1.8 liter you would likely use nitrous as a spool aid, but never stop adding it as boost increased. Eventually engine breathing should become the biggest obstacle, no matter what the manifold pressure.
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Old 09-21-2009, 02:20 PM   #20
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Isn't that already the biggest obstacle?
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