capella re
04-01-2010, 10:20 AM
Transmission and engine mounts:
The original 13B TurboII transmission was used, with the original transmission cross member bolted at all the same original places.
The 20B flywheel was replaced with the original TurboII flywheel although using the 20B counterweight.
The original TurboII starter motor was also used.
In order to fabricate engine mounts, the transmission was bolted to the engine and to the body, thereby leaving the engine unmounted at the front.
The 20B engine mounts are located to the rear of the engine (on the cast iron housing between the rear two rotors).
The original engine cross member is used in a modified form, cut and welded towards the back of the cross member to accommodate the original 20B engine mounts.
The standard RX7 TurboII drive shaft and differential are used.
Other engine mounting issues:
As the 20B is about 7 inches longer than the 13B TurboII engine, the original radiator was replaced with an aluminium one located further forward (and necessitates using some big electric fans).
In this case, with the large intercooler, there was significant modification towards the nose of the car to accommodate it.
Furthermore due to a lack of room the Air Conditioner cannot be used and the front sway bar need to be adapted because the 20B engine will hit the sway bar.
Turbos, fuel system and exhaust:
Due to the complex layout of the 20B's original sequential turbos, these were removed and replaced with a single large turbo.
The original 20B in the Eunos Cosmo generates a stock 280hp, up to around 350-400 with minor modifications.
With the T-64 turbonetics single turbo, the target is at least 500hp.
550cc injectors have been used on the primaries and 1200cc injectors on the secondaries. Given that, the engine should be capable of 10 - 12 lbs boost with a little left over in injector capacity so it does not lean out.
The exhaust is custom made, with a 3.5 inch downpipe to a 3.5 inch Borla stainless steel resonator branching into two 3 inch pipes and two 3 inch exhaust, all made from stainless steel. Evidently it sounds great!
Engine Management:
Two electromotive TEC1 engine management systems are used, with two sets of three coils each, one spark plug per coil (the other side of the coil is grounded).
(3 rotors x 2 plugs = 6 plugs, 1 coil per plug)
Two crank angle sensors are used, which are 180 degrees apart, one for leading and the other side, trailing. These sensors were installed inside the original 20B crank angle sensor. (The 20B crank angle sensor is located at the same place where the 13B distributor is).
The TEC units manage the ignition timing as well as fuel injection, with the main computers mounted in the polished aluminium compartment and the coil packs mounted on the suspension tower (TEC II units combine the computer and coil pack into one unit).
this was taken from craigs rotary page (thanks buddy)
heres another excellent link on how to http://www.3rotor.com/fc_rx7_build.htm
http://images.turbomagazine.com/features/0611sccp_02z+mazda_rx7_fd3s+20b_engine_view.jpg
http://www.3rotor.com/images/fc_rx7_build/fc-20b-11.jpg
http://www.3rotor.com/images/fc_rx7_build/fc_rx7_5.jpg
http://www.3rotor.com/images/fc_rx7_build/fc-20b-14.jpg
this ones naturally aspirated
http://www.3rotor.com/images/fc_rx7_build/fc-20b-9.jpg
images taken from 3rotor.com
some common questions on the 20b
Q: What is a 20B engine?
A: A 20B engine is a 3-rotor engine based on the 13B series engines.
Q: Which production cars came with a 20B engine?
A: Only the 1990-1995 JC Cosmo luxury car with an automatic transmission, which was only sold in Japan. See "JC Cosmo" in the Links page below.
Q: Are there different kinds of 20B engines?
A: Yes, there is the JC Cosmo's 20B-REW engine with two turbochargers, and there is the 20B Race non-turbo peripheral-port engine made by Mazdaspeed Motorsports Development. See "About 3-Rotor Engines" in the Links page below.
Q: What was the performance rating of the stock JC Cosmo 20B-REW?
A: 280ps @ 6500rpm, 41.0kg-m @ 3000rpm (276bhp @ 6500rpm, 296 ft-lbs @ 3000rpm).
Q: Is the 20B the only engine covered in this forum?
A: No, any rotary engine with 3 or more rotors is discussed here.
Q: Can I make my own 3 or 4-rotor engine?
A: Yes, but it is rather difficult, and only the top rotary engine shops have succeeded in this.
Q: How much does it cost to install a 3-rotor engine in my RX-7?
A: In the US, it costs about $10,000 to do it yourself, and about $35,000 for a professional conversion. Prices are lower in countries with lower labor costs and better access to Japanese engines, such as AUS, NZ, and Japan. See "3-Rotor Conversion Planning Websites" in the Links page below.
Q: Where can I buy a 20B engine?
A: New parts are available from Mazdaspeed Motorsports Development, and for used engines see "Where to Buy Used 20B Engines" in the Links page below.
Q: Can I use the stock JC Cosmo ECU to run a 20B engine in my RX-7?
A: Yes, but it takes a lot of work, and it would not stack up to the higher power levels available from aftermarket ECU's.
Q: Does the 20B engine attach to the stock RX-7 transmission?
A: Yes.
Q: Will the 20B engine attach to the stock RX-7 engine mounts?
A: No, custom mounts are required.
Q: Can 13B rotors and rotor housings fit on the 20B engine?
A: Yes.
Q: Will a 20B conversion ruin the "perfect" weight distribution of my RX-7?
A: The static weight distribution can remain 50/50 if you plan your project accordingly. A 20B conversion is a custom procedure, and how you go about it is your own choice.
another link to 20b's in fc's 20b FAQ and Links - RX7Club.com
i think if you were seriously considering this, the biggest draw back would have to be the cost of a genuine 20b these days. most 20b's that you see in drag cars are actually the 3 13b rotor configurations with a 20b eccentric shaft (or custom made one) dont quote me on which cars run which as i have no idea, but in most magizine articles on 20b engines they have been 13b rotors made to a 20b (nothing wrong with that just an intesting point)
Anyone on here actually seriously considered this at some point or another?? any information you could submit for or against this, chuck it up for us to look at.
The original 13B TurboII transmission was used, with the original transmission cross member bolted at all the same original places.
The 20B flywheel was replaced with the original TurboII flywheel although using the 20B counterweight.
The original TurboII starter motor was also used.
In order to fabricate engine mounts, the transmission was bolted to the engine and to the body, thereby leaving the engine unmounted at the front.
The 20B engine mounts are located to the rear of the engine (on the cast iron housing between the rear two rotors).
The original engine cross member is used in a modified form, cut and welded towards the back of the cross member to accommodate the original 20B engine mounts.
The standard RX7 TurboII drive shaft and differential are used.
Other engine mounting issues:
As the 20B is about 7 inches longer than the 13B TurboII engine, the original radiator was replaced with an aluminium one located further forward (and necessitates using some big electric fans).
In this case, with the large intercooler, there was significant modification towards the nose of the car to accommodate it.
Furthermore due to a lack of room the Air Conditioner cannot be used and the front sway bar need to be adapted because the 20B engine will hit the sway bar.
Turbos, fuel system and exhaust:
Due to the complex layout of the 20B's original sequential turbos, these were removed and replaced with a single large turbo.
The original 20B in the Eunos Cosmo generates a stock 280hp, up to around 350-400 with minor modifications.
With the T-64 turbonetics single turbo, the target is at least 500hp.
550cc injectors have been used on the primaries and 1200cc injectors on the secondaries. Given that, the engine should be capable of 10 - 12 lbs boost with a little left over in injector capacity so it does not lean out.
The exhaust is custom made, with a 3.5 inch downpipe to a 3.5 inch Borla stainless steel resonator branching into two 3 inch pipes and two 3 inch exhaust, all made from stainless steel. Evidently it sounds great!
Engine Management:
Two electromotive TEC1 engine management systems are used, with two sets of three coils each, one spark plug per coil (the other side of the coil is grounded).
(3 rotors x 2 plugs = 6 plugs, 1 coil per plug)
Two crank angle sensors are used, which are 180 degrees apart, one for leading and the other side, trailing. These sensors were installed inside the original 20B crank angle sensor. (The 20B crank angle sensor is located at the same place where the 13B distributor is).
The TEC units manage the ignition timing as well as fuel injection, with the main computers mounted in the polished aluminium compartment and the coil packs mounted on the suspension tower (TEC II units combine the computer and coil pack into one unit).
this was taken from craigs rotary page (thanks buddy)
heres another excellent link on how to http://www.3rotor.com/fc_rx7_build.htm
http://images.turbomagazine.com/features/0611sccp_02z+mazda_rx7_fd3s+20b_engine_view.jpg
http://www.3rotor.com/images/fc_rx7_build/fc-20b-11.jpg
http://www.3rotor.com/images/fc_rx7_build/fc_rx7_5.jpg
http://www.3rotor.com/images/fc_rx7_build/fc-20b-14.jpg
this ones naturally aspirated
http://www.3rotor.com/images/fc_rx7_build/fc-20b-9.jpg
images taken from 3rotor.com
some common questions on the 20b
Q: What is a 20B engine?
A: A 20B engine is a 3-rotor engine based on the 13B series engines.
Q: Which production cars came with a 20B engine?
A: Only the 1990-1995 JC Cosmo luxury car with an automatic transmission, which was only sold in Japan. See "JC Cosmo" in the Links page below.
Q: Are there different kinds of 20B engines?
A: Yes, there is the JC Cosmo's 20B-REW engine with two turbochargers, and there is the 20B Race non-turbo peripheral-port engine made by Mazdaspeed Motorsports Development. See "About 3-Rotor Engines" in the Links page below.
Q: What was the performance rating of the stock JC Cosmo 20B-REW?
A: 280ps @ 6500rpm, 41.0kg-m @ 3000rpm (276bhp @ 6500rpm, 296 ft-lbs @ 3000rpm).
Q: Is the 20B the only engine covered in this forum?
A: No, any rotary engine with 3 or more rotors is discussed here.
Q: Can I make my own 3 or 4-rotor engine?
A: Yes, but it is rather difficult, and only the top rotary engine shops have succeeded in this.
Q: How much does it cost to install a 3-rotor engine in my RX-7?
A: In the US, it costs about $10,000 to do it yourself, and about $35,000 for a professional conversion. Prices are lower in countries with lower labor costs and better access to Japanese engines, such as AUS, NZ, and Japan. See "3-Rotor Conversion Planning Websites" in the Links page below.
Q: Where can I buy a 20B engine?
A: New parts are available from Mazdaspeed Motorsports Development, and for used engines see "Where to Buy Used 20B Engines" in the Links page below.
Q: Can I use the stock JC Cosmo ECU to run a 20B engine in my RX-7?
A: Yes, but it takes a lot of work, and it would not stack up to the higher power levels available from aftermarket ECU's.
Q: Does the 20B engine attach to the stock RX-7 transmission?
A: Yes.
Q: Will the 20B engine attach to the stock RX-7 engine mounts?
A: No, custom mounts are required.
Q: Can 13B rotors and rotor housings fit on the 20B engine?
A: Yes.
Q: Will a 20B conversion ruin the "perfect" weight distribution of my RX-7?
A: The static weight distribution can remain 50/50 if you plan your project accordingly. A 20B conversion is a custom procedure, and how you go about it is your own choice.
another link to 20b's in fc's 20b FAQ and Links - RX7Club.com
i think if you were seriously considering this, the biggest draw back would have to be the cost of a genuine 20b these days. most 20b's that you see in drag cars are actually the 3 13b rotor configurations with a 20b eccentric shaft (or custom made one) dont quote me on which cars run which as i have no idea, but in most magizine articles on 20b engines they have been 13b rotors made to a 20b (nothing wrong with that just an intesting point)
Anyone on here actually seriously considered this at some point or another?? any information you could submit for or against this, chuck it up for us to look at.