Gonna get flamed, but unsure what to search for exactly
#1
Drive to the unknown.
Thread Starter
Gonna get flamed, but unsure what to search for exactly
Okay, so I got my 1st FD today. HORAH!!!!! It's a 93' Touringm but my main question lays towards the sequntial Twin Turbo set up.....
The 10-8-10 Deal...... does this mean that the first turbo spools to 10psi and then there's a 2 psi drop when the second turbo spools up, and then boost stops at 10 psi again? if so what's the purpose for the secondary turbine? also, going from a sequntial setup to a standard duel set-up, what are the major differences? thanx and also if you can tell me what to search under, you don't need to waste time answering my ? thanx ya'll
The 10-8-10 Deal...... does this mean that the first turbo spools to 10psi and then there's a 2 psi drop when the second turbo spools up, and then boost stops at 10 psi again? if so what's the purpose for the secondary turbine? also, going from a sequntial setup to a standard duel set-up, what are the major differences? thanx and also if you can tell me what to search under, you don't need to waste time answering my ? thanx ya'll
#3
Rotary Freak
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The benefits of having the twins from my understanding is that even though it is running the same PSI as on the primary, the intake temps drop dramatically because the exhaust is routed through both turbos, instead of just the primary. As for the differences in the sequential system vs. a parallel set up, it seems that the reason people do the non-sequential swap is to get away from the problematic sequential system. I personally love the sequential response, theres no subsitute for the quick spooling power. But the parallel set up tends to have less problems...
Last edited by Cgotto6; 03-03-05 at 07:25 PM.
#4
Drive to the unknown.
Thread Starter
ahhh..... so the stock boost setting is 10psi at full then? if so, then when increasing boost, is there 2 wastegates, or 1 that controls both turbines?
#5
Urban Combat Vet
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http://www.autosportracetech.com/RX-7/rx7stuff.htm
Good luck with your FD, this should get you started.
Good luck with your FD, this should get you started.
#6
Rx7 Wagon
iTrader: (16)
the reason two turbos are employed instead of one is for spool. one small turbo spools up for the first half of the rpm band, then one turbo isnt enough anymore so another on ekicks in to pick up the slack. im sure temperature is adversely affected by this, but this is a side issue. the purpose is to get instant boost.
#7
There is one wastegate to control both. However, there is a thing that is really similar to a wastegate that bleeds exhaust off during primary-only operation and pre-spools the secondary turbo. But when both turbos are running, the wastegate-like-pre-spool-gate has no effect on boost level -- the single wastegate is the only way to regulate the boost level.
One of the stock turbos could not provide enough flow to make 10 psi at redline. And it would be way out of its efficiency range long before that, raising the intake temps to dangerous levels. So, with the sequential system you can have one small turbo run at low RPM for good response, and then bring a second turbo in when the first one starts to run out of flow. The two turbos are the same size, and both of the turbos are in use above 4500 RPM (aka "the transition") when you are under boost.
-Max
One of the stock turbos could not provide enough flow to make 10 psi at redline. And it would be way out of its efficiency range long before that, raising the intake temps to dangerous levels. So, with the sequential system you can have one small turbo run at low RPM for good response, and then bring a second turbo in when the first one starts to run out of flow. The two turbos are the same size, and both of the turbos are in use above 4500 RPM (aka "the transition") when you are under boost.
-Max
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#9
omgwtfposlol
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just so you know... do NOT increase the boost without an ECU. our stock ECUs are NOT mapped for any higher boost than 10 psi. you can do flow mods like intake/dp/cat back, but keep the boost in check. a boost gage is a huge reliability mod on these cars. look out for spiking on transition instead of a dip, caused by too much prespool without enough wg open in primary operation.
#12
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Originally Posted by maxcooper
There is one wastegate to control both. However, there is a thing that is really similar to a wastegate that bleeds exhaust off during primary-only operation and pre-spools the secondary turbo. But when both turbos are running, the wastegate-like-pre-spool-gate has no effect on boost level -- the single wastegate is the only way to regulate the boost level.
-Max
-Max
[edit] Check the service highlights, page F22. It indicates the wastegate stays shut until midrange. (its on my site)
Dave
Last edited by dgeesaman; 03-04-05 at 08:50 AM.
#13
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Dave,
I believe that max's post says exactly what your write up says - prespool door regulates boost below transistion and wastegate regulates boost after transition. That is what I got from max's post when I read it. You may have misunderstood because he says the prespool door is "wastegate-like".
I believe that max's post says exactly what your write up says - prespool door regulates boost below transistion and wastegate regulates boost after transition. That is what I got from max's post when I read it. You may have misunderstood because he says the prespool door is "wastegate-like".
#14
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Originally Posted by maxcooper
One of the stock turbos could not provide enough flow to make 10 psi at redline. And it would be way out of its efficiency range long before that, raising the intake temps to dangerous levels. So, with the sequential system you can have one small turbo run at low RPM for good response, and then bring a second turbo in when the first one starts to run out of flow. The two turbos are the same size, and both of the turbos are in use above 4500 RPM (aka "the transition") when you are under boost.
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Originally Posted by widebody2
You sure about that?
#19
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Originally Posted by BlueRex
Not positive, but I seem to remember reading all the info I previously posted in an old thread. If someone knows better please correct me.
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Originally Posted by rynberg
You're wrong. Both turbos are the same size. The Cosmo used different size turbos for its sequential setup, not the RX-7.
However, I am almost certain I remember reading a thread of someone that dyno'd his 99 spec twins and it clearly showed his power curve leveling off before transition and the explanation was that the primary on the 99 twins "runs out of breath" earlier then the previous turbos. Of course it was in the 3rd gen dyno section which seems to have been cleaned up recently.
Originally Posted by turbojeff
Sequential refers to the way the turbos are staged, not the size.
93+ RX-7s are all factory *TRUE* sequential twin turbos.
93+ RX-7s are all factory *TRUE* sequential twin turbos.
#22
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Originally Posted by turbojeff
No, I don't think I did.
I *thought* you said that the 93-98 weren't true sequential turbos, which I thought I politely corrected.
I *thought* you said that the 93-98 weren't true sequential turbos, which I thought I politely corrected.
#23
Moderator
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Originally Posted by novadan67
Dave,
I believe that max's post says exactly what your write up says - prespool door regulates boost below transistion and wastegate regulates boost after transition. That is what I got from max's post when I read it. You may have misunderstood because he says the prespool door is "wastegate-like".
I believe that max's post says exactly what your write up says - prespool door regulates boost below transistion and wastegate regulates boost after transition. That is what I got from max's post when I read it. You may have misunderstood because he says the prespool door is "wastegate-like".
Dave
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