how do the twins work, exactly.
08-26-02, 03:13 PM
#1
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how do the twins work, exactly.
I know the first small turbo is spooled by 3000 rpm, then sends exhaust gases to the larger 2nd turbo. at 4500 the 2nd turbo kicks in. Does in run in parallel to the first or does the first stop running when the 2nd turbo is spooled?
David
David
08-26-02, 03:38 PM
#2
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Close but no cigar.
Both turbos are the same size.
Primary is spooled and should get full boost around 2800rpms or so and as the primary is spooled up the secondary is getting pre-spooled for operation and at a designated RPM(4500) alot happends but to boil it down the doors open and the secondary comes on line and they both work together until redline. A good operating seq systems stock should get a 10-8-10 pattern and the closer to redline the boost will decreas by 1-2 psi. That is normal but after you mod with a ECU you can keep it to what ever psi desired. Just dont blow it up by running 15 psi
. I think you should not run more than 12-13 psi on the street if you want a long lasting set of turbos. IMO.
Also use the search function to find out more or check out this site www.rx7turboturbo.com as it has tons of good info on this car
-Rikki
Both turbos are the same size.
Primary is spooled and should get full boost around 2800rpms or so and as the primary is spooled up the secondary is getting pre-spooled for operation and at a designated RPM(4500) alot happends but to boil it down the doors open and the secondary comes on line and they both work together until redline. A good operating seq systems stock should get a 10-8-10 pattern and the closer to redline the boost will decreas by 1-2 psi. That is normal but after you mod with a ECU you can keep it to what ever psi desired. Just dont blow it up by running 15 psi
. I think you should not run more than 12-13 psi on the street if you want a long lasting set of turbos. IMO.Also use the search function to find out more or check out this site www.rx7turboturbo.com as it has tons of good info on this car
-Rikki
08-26-02, 03:42 PM
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Originally posted by Dont_Be_A_Rikki
Close but no cigar.
Both turbos are the same size.
Primary is spooled and should get full boost around 2800rpms or so and as the primary is spooled up the secondary is getting pre-spooled for operation and at a designated RPM(4500) alot happends but to boil it down the doors open and the secondary comes on line and they both work together until redline. A good operating seq systems stock should get a 10-8-10 pattern and the closer to redline the boost will decreas by 1-2 psi. That is normal but after you mod with a ECU you can keep it to what ever psi desired. Just dont blow it up by running 15 psi. I think you should not run more than 12-13 psi on the street if you want a long lasting set of turbos. IMO.
Also use the search function to find out more or check out this site www.rx7turboturbo.com as it has tons of good info on this car
rikki!!
I know about the search!!! we just don't get along. LOL. Really its difficult to narrow the phrase down. I tried "Sequential and work" but it did not work they way I want.
You answered my question, I appreciate it!
-Rikki
Close but no cigar.
Both turbos are the same size.
Primary is spooled and should get full boost around 2800rpms or so and as the primary is spooled up the secondary is getting pre-spooled for operation and at a designated RPM(4500) alot happends but to boil it down the doors open and the secondary comes on line and they both work together until redline. A good operating seq systems stock should get a 10-8-10 pattern and the closer to redline the boost will decreas by 1-2 psi. That is normal but after you mod with a ECU you can keep it to what ever psi desired. Just dont blow it up by running 15 psi
. I think you should not run more than 12-13 psi on the street if you want a long lasting set of turbos. IMO.Also use the search function to find out more or check out this site www.rx7turboturbo.com as it has tons of good info on this car
rikki!!
I know about the search!!! we just don't get along. LOL. Really its difficult to narrow the phrase down. I tried "Sequential and work" but it did not work they way I want.
You answered my question, I appreciate it!
-Rikki
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08-26-02, 04:41 PM
#8
Senior Member
hell, i swaer that the extra set in my garage is not the same size. they might be different though. they came with the car. i have not had a need for them yet. i do know that there have been people to upgrade the primary though.....
08-26-02, 04:42 PM
#9
The sequential twin turbocharger system consists of two turbochargers (primary and secondary) fitted in line with eachother. In the low-speed, light-load range (under 3000 rpm), turbocharging is done only by the primary turbocharger; in the high-speed, heavy-load range (over 4500 rpm), turbocharging is done by the primary and secondary turbochargers in union.
To prevent a drop in boost pressure when the secondary turbocharger begins to operate, the secondary turbocharger is made to spin prior to its operation (3000-4500 rpm).
The sequential twin turbocharger system consists of the primary and secondary turbochargers and the actuators and solenoid valves (turbo precontrol, turbo control, wastegate control, charge control, charge relief).
*from the 1993 Mazda RX-7 Workshop Manual
To prevent a drop in boost pressure when the secondary turbocharger begins to operate, the secondary turbocharger is made to spin prior to its operation (3000-4500 rpm).
The sequential twin turbocharger system consists of the primary and secondary turbochargers and the actuators and solenoid valves (turbo precontrol, turbo control, wastegate control, charge control, charge relief).
*from the 1993 Mazda RX-7 Workshop Manual
08-26-02, 07:24 PM
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Originally posted by diablone
With the boost patterns like 10-8-10, what are these numbers comming from? I realise it's 10psi, 8psi, 10psi, but whats happening to report these?
With the boost patterns like 10-8-10, what are these numbers comming from? I realise it's 10psi, 8psi, 10psi, but whats happening to report these?
You hit 10 PSI around 3K, at 4500 (transition) you fall back to 8 PSI, then quickly regain back to 10.
Unless your like 99 pct of the FD owners where your turbos are not working correctly, lol
08-26-02, 07:26 PM
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Originally posted by diablone
With the boost patterns like 10-8-10, what are these numbers comming from? I realise it's 10psi, 8psi, 10psi, but whats happening to report these?
With the boost patterns like 10-8-10, what are these numbers comming from? I realise it's 10psi, 8psi, 10psi, but whats happening to report these?
Seriously though, the drop is a transitional period where the two turbos are combined. The initial drop must be due to either lower pre-spooled boost, or the fact that the TCA (a big exhaust deflector) suddenly diverted a large portion of the exhaust gas away from the primary turbocharger. Not sure if there is any other explanation.
Last edited by spooledUP7; 08-26-02 at 07:31 PM.
08-26-02, 07:28 PM
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Originally posted by spooledUP7
A boost gauge that was so sorely left out of the OEM design.
A boost gauge that was so sorely left out of the OEM design.
David
08-26-02, 07:50 PM
#14
Originally posted by ZeroBanger
IN a nutshell...
You hit 10 PSI around 3K, at 4500 (transition) you fall back to 8 PSI, then quickly regain back to 10.
Unless your like 99 pct of the FD owners where your turbos are not working correctly, lol
IN a nutshell...
You hit 10 PSI around 3K, at 4500 (transition) you fall back to 8 PSI, then quickly regain back to 10.
Unless your like 99 pct of the FD owners where your turbos are not working correctly, lol
Originally posted by spooledUP7
Seriously though, the drop is a transitional period where the two turbos are combined. The initial drop must be due to either lower pre-spooled boost, or the fact that the TCA (a big exhaust deflector) suddenly diverted a large portion of the exhaust gas away from the primary turbocharger. Not sure if there is any other explanation.
Seriously though, the drop is a transitional period where the two turbos are combined. The initial drop must be due to either lower pre-spooled boost, or the fact that the TCA (a big exhaust deflector) suddenly diverted a large portion of the exhaust gas away from the primary turbocharger. Not sure if there is any other explanation.
08-27-02, 01:07 AM
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The drop in boost at 4500rpm is due to the 2nd turbo not being spooled enough. This can be adjusted...
I know it's silly, but you forgot to mention that the charge relief valve, which looks exactly like the stock BOV, vents some of the boost created by the 2nd turbo during prespool. The charge control valve is what actually allows boost from the 2nd turbo to mix in with the 1st turbo at 4500rpm. With the charge control closed, it allows full boost from the 1st turbo to reach the engine under 4500rpm.
I know it's silly, but you forgot to mention that the charge relief valve, which looks exactly like the stock BOV, vents some of the boost created by the 2nd turbo during prespool. The charge control valve is what actually allows boost from the 2nd turbo to mix in with the 1st turbo at 4500rpm. With the charge control closed, it allows full boost from the 1st turbo to reach the engine under 4500rpm.
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