Can you Put RX-7 Twin turbo set?
Can you Put RX-7 Twin turbo set?
03-27-2008 | 09:05 PM
#12
Power!!
Joined: Feb 2004
Posts: 4,412
Likes: 3
From: Sunny See attle
For a more serious answer:
Modern turbos today are more efficient and have better response than the twin setup on the RX7. You will have a cheaper more reliable better performing car with any of the current aftermarket kits than using the older twin turbo setup.
Modern turbos today are more efficient and have better response than the twin setup on the RX7. You will have a cheaper more reliable better performing car with any of the current aftermarket kits than using the older twin turbo setup.
03-27-2008 | 10:30 PM
#16
Power!!
Joined: Feb 2004
Posts: 4,412
Likes: 3
From: Sunny See attle
Yes. And it is also more powerful and probably more reliable than the old RX7 twin turbo setup.
I am not saying twin turbos are obsolete but you can get more for less now than what that setup offered. And if you look at the BMW tq and HP curves you can tell it's two tiny turbos that most likely an aftermarket tuner wouldn't size themselves. It tends to run out of breath up top kinda like the Greddy kit.
I am not saying twin turbos are obsolete but you can get more for less now than what that setup offered. And if you look at the BMW tq and HP curves you can tell it's two tiny turbos that most likely an aftermarket tuner wouldn't size themselves. It tends to run out of breath up top kinda like the Greddy kit.
03-27-2008 | 11:54 PM
#20
Not the same. BMW's system is two small turbos in parallel, each being driven off of three cylinders. Think of it as two small turbocharged inline 3-cylinder engines sharing a common crank.
The twin turbo setup from the FD RX7 was a sequential setup. At low RPMs, exhaust gasses would be diverted to one of the small turbos to provide quick response. Once the first turbo's wastegate started to open, that unused exhaust energy was diverted to pre-spool the secondary turbo, which started adding its compressor charge as the engine passed 4500 rpm. So essentially the FD had one small turbo from idle to 4500rpm, then two small (pre-spooled) turbos from 4500rpm to redline.
Smart idea in theory (especially before the advent of effective variable geometry turbos), but lousy in execution. The control system on the early FDs was vacuum-controlled, which led to a huge number of problems due to vacuum leaks and plumbing problems. A lot of FD owners converted the stock twins to a parallel setup (both turbos worked from idle to redline) which improved reliability but increased turbo lag. Some went to a larger single turbo. Others, like me, tore their hair out in frustration, sold the car, and bought a Miata.
To the OP - not only would you not want the twins from the FD, but you'd have a hard time making them work. They certainly wouldn't bolt right on. The RX-8's ECU couldn't operate the sequential control system, and the Renesis has a different exhaust port configuration anyway, so you'd have to custom fab the manifold. You'd be better off buying one of the available kits.
Last note - "cheap" and "aftermarket turbo kit" usually aren't used in the same sentence, unless they're closely followed by "piece of crap".
The twin turbo setup from the FD RX7 was a sequential setup. At low RPMs, exhaust gasses would be diverted to one of the small turbos to provide quick response. Once the first turbo's wastegate started to open, that unused exhaust energy was diverted to pre-spool the secondary turbo, which started adding its compressor charge as the engine passed 4500 rpm. So essentially the FD had one small turbo from idle to 4500rpm, then two small (pre-spooled) turbos from 4500rpm to redline.
Smart idea in theory (especially before the advent of effective variable geometry turbos), but lousy in execution. The control system on the early FDs was vacuum-controlled, which led to a huge number of problems due to vacuum leaks and plumbing problems. A lot of FD owners converted the stock twins to a parallel setup (both turbos worked from idle to redline) which improved reliability but increased turbo lag. Some went to a larger single turbo. Others, like me, tore their hair out in frustration, sold the car, and bought a Miata.
To the OP - not only would you not want the twins from the FD, but you'd have a hard time making them work. They certainly wouldn't bolt right on. The RX-8's ECU couldn't operate the sequential control system, and the Renesis has a different exhaust port configuration anyway, so you'd have to custom fab the manifold. You'd be better off buying one of the available kits.
Last note - "cheap" and "aftermarket turbo kit" usually aren't used in the same sentence, unless they're closely followed by "piece of crap".
Last edited by altiain; 03-27-2008 at 11:56 PM.
03-28-2008 | 05:32 PM
#22
is adjusting valve lash
Joined: Sep 2007
Posts: 1,060
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From: hollywooood!
cheap and good don't mix well together.
but and all of altian's help may seem to even curb my curiosity.
so at tis, i think even the cheapest available turbo kit is your best investment on a turbo set-up. unless you're trying to customize fitting of sorts.
good thing someone mentioned the variable turbos. much like porsche, the acura rdx have one powering its 2.3 technocharged motor. isn't the variable turbo porsche technology???
but and all of altian's help may seem to even curb my curiosity.
so at tis, i think even the cheapest available turbo kit is your best investment on a turbo set-up. unless you're trying to customize fitting of sorts.
good thing someone mentioned the variable turbos. much like porsche, the acura rdx have one powering its 2.3 technocharged motor. isn't the variable turbo porsche technology???
03-28-2008 | 07:01 PM
#23
Power!!
Joined: Feb 2004
Posts: 4,412
Likes: 3
From: Sunny See attle
Agreed. But as your example beautifully describes it would definitely be cheaper to buy one of the current aftermarket kits for the 8 than convert the 7's twin sequential setup.
03-28-2008 | 10:33 PM
#24
Registered User
Joined: Jun 2006
Posts: 45
Likes: 0
From: ATL, GA
Not the same. BMW's system is two small turbos in parallel, each being driven off of three cylinders. Think of it as two small turbocharged inline 3-cylinder engines sharing a common crank.
The twin turbo setup from the FD RX7 was a sequential setup. At low RPMs, exhaust gasses would be diverted to one of the small turbos to provide quick response. Once the first turbo's wastegate started to open, that unused exhaust energy was diverted to pre-spool the secondary turbo, which started adding its compressor charge as the engine passed 4500 rpm. So essentially the FD had one small turbo from idle to 4500rpm, then two small (pre-spooled) turbos from 4500rpm to redline.
Smart idea in theory (especially before the advent of effective variable geometry turbos), but lousy in execution. The control system on the early FDs was vacuum-controlled, which led to a huge number of problems due to vacuum leaks and plumbing problems. A lot of FD owners converted the stock twins to a parallel setup (both turbos worked from idle to redline) which improved reliability but increased turbo lag. Some went to a larger single turbo. Others, like me, tore their hair out in frustration, sold the car, and bought a Miata.
To the OP - not only would you not want the twins from the FD, but you'd have a hard time making them work. They certainly wouldn't bolt right on. The RX-8's ECU couldn't operate the sequential control system, and the Renesis has a different exhaust port configuration anyway, so you'd have to custom fab the manifold. You'd be better off buying one of the available kits.
Last note - "cheap" and "aftermarket turbo kit" usually aren't used in the same sentence, unless they're closely followed by "piece of crap".
The twin turbo setup from the FD RX7 was a sequential setup. At low RPMs, exhaust gasses would be diverted to one of the small turbos to provide quick response. Once the first turbo's wastegate started to open, that unused exhaust energy was diverted to pre-spool the secondary turbo, which started adding its compressor charge as the engine passed 4500 rpm. So essentially the FD had one small turbo from idle to 4500rpm, then two small (pre-spooled) turbos from 4500rpm to redline.
Smart idea in theory (especially before the advent of effective variable geometry turbos), but lousy in execution. The control system on the early FDs was vacuum-controlled, which led to a huge number of problems due to vacuum leaks and plumbing problems. A lot of FD owners converted the stock twins to a parallel setup (both turbos worked from idle to redline) which improved reliability but increased turbo lag. Some went to a larger single turbo. Others, like me, tore their hair out in frustration, sold the car, and bought a Miata.
To the OP - not only would you not want the twins from the FD, but you'd have a hard time making them work. They certainly wouldn't bolt right on. The RX-8's ECU couldn't operate the sequential control system, and the Renesis has a different exhaust port configuration anyway, so you'd have to custom fab the manifold. You'd be better off buying one of the available kits.
Last note - "cheap" and "aftermarket turbo kit" usually aren't used in the same sentence, unless they're closely followed by "piece of crap".
I have modified my sequential setup and slightly simplified the "rats nest". Now, my transition comes sooner and quicker which helps greatly on the low end.
Right now, the car makes close to 320whp on the stock turbos, and after they go, I will be switching to the BNR Stage III. I'm not particularly fond of the single turbo setup, and I couldn't live with the lack of low end running the twins in parallel would produce.
To make my point, the FD turbos were designed for the FD. Putting them on my Rx8 never crossed my mind. Totally different configurations.
--Edit--
The dyno # in my sig is the last verified dyno run. I have made various upgrades since then.
