20b first gen
Senior Member
Joined: Mar 2005
Posts: 108
From: Midway, KY
I'm sorry don't know much about 20b installations but I converted my fb to a 13b and what a change! I can only imagine what *** you could kick with a 3-rotor. 2400-2500 lbs(if u remove p/s, a/c, emissions) and 300 horses(if stock) and 300 ft/lbs would be awesome. It would be a great sleeper. I'm sure u would have to fabricate the mounts and change out the wiring harnesses and ecu.....along with transmission related adjustment. Hopefully, someone more experienced will give ya info but I give a thumbs up on the idea!
Senior Member
Joined: May 2002
Posts: 22,465
From: California
shouldnt be too hard. new mounts need to be made. would help if the trans was moved back some, but its not needed. you need a larger radiator, exhaust needs to be made, ecu/carb etc etc
its a huge project, but its not really difficult
its a huge project, but its not really difficult
Senior Member
Joined: Jan 2006
Posts: 1,114
I have seen a couple 20b first gens. One was here in the States. The guy had to make a whole new cross member. Personally though I would just shorten the shifter length a little more. You are already in the tranny why not just take off a little more.
If you did that though I am not sure what kind of issues you would run into with the firewall.
Most of the work is not that hard but very tedious. I have spent just over 400 hours on my 13b-rew swap. I am a very slow worker though and I like to make sure that everything is inorder before I proceed. Measure twice cut once. I also have a lot of custom work that has been done.(ie h-mount)
If you undergo something like this expect to pay a pretty penny. 20b's in themselves are not that cheap.
You will follow most of the procedures of a 13b swap there are just a few things that are different.
Also no 20b's came with manual transmissions. This means that you will have to swap counterweights.
How much money do you have to work with. I would consertivley say that you would need about 6-8k to pull it off correctly. Not to mention a lot of man hours.
If you did that though I am not sure what kind of issues you would run into with the firewall.
Most of the work is not that hard but very tedious. I have spent just over 400 hours on my 13b-rew swap. I am a very slow worker though and I like to make sure that everything is inorder before I proceed. Measure twice cut once. I also have a lot of custom work that has been done.(ie h-mount)
If you undergo something like this expect to pay a pretty penny. 20b's in themselves are not that cheap.
You will follow most of the procedures of a 13b swap there are just a few things that are different.
Also no 20b's came with manual transmissions. This means that you will have to swap counterweights.
How much money do you have to work with. I would consertivley say that you would need about 6-8k to pull it off correctly. Not to mention a lot of man hours.
Thread Starter
Member
Joined: Feb 2006
Posts: 38
thancks ive got about $6-7 and il do mostly every think my self i know alot of people in the industry
and all parts will be at cost. this dosent mean im gonna spend less it just means im gonna get a lot more for that money. im gonna go with na for now with semi p port the bellow is an extract from craigs rotary page
Peripheral port secondaries
This idea was originally created by Mazda during the mid-late 1960s with experimental engines. It was also used in Cosmo racing engines. However, as the Cosmo engine made a mere 2 horsepower more than the standard production engine the idea was not used thereafter. (This small gain is probably because of the noise restrictions placed on it, hence not being able to use a suitable exhaust system).
My friend resurrected the idea and to recently it has been used by others. Due to the sizeable intake ports - the peripheral ports are 45mm diameter plus the street ports, the volumetric efficiency is very impressive. Volumetric efficiency is a measure of the ratio of the combustion chamber size to how much air can enter the engine while the intake port is open, and in turn the more air/fuel mixture the higher the power.
In fact, this engine MAY almost be over 100%. This means that the engine takes in more air than it's capacity, which is unusual for a naturally aspirated engine - normally only turbocharged engines and highly tuned racing engines are capable of this. This explains why a peripheral port engines are high powered.
In fact, a 13B with this configuration with a Holley carburettor, electronic ignition, muffled exhaust has been dyno tested at 350 BHP ("flywheel horsepower" -calculated by the dyno)
Furthermore, due to the peripheral port secondary being a "static column of air", this tends to stop the traditional peripheral port rough idle. This is because the air is not flowing into the port, so it has a certain amount of resistance to movement or 'springiness' which limits how much of the exhaust gets around the apex seal into the fresh mixture.
Also, as the air tends to be very turbulent due to the air streams colliding, atomisation is good, resulting in a torque curve which is quite flat across the RPM range.
Given the characteristics across the RPM range, this engine combination is almost comparable to a turbo engine. It was not much more difficult to drive than a standard engine. The only problem is that this engine requires a reasonably free flowing (noisy) exhaust.
Construction of the engine
The "Mazda Factory" primary ports in the intermediate housing are filled with epoxy such as Devcon or similar, as described in the Racing Beat catalogue.
The street ports are a conventional street port. Sorry, I'm not sure of the exact port shape or timing used, but I think it was fairly close to stock to enable good low down torque (which is also boosted slightly by the relatively long induction tubes.)
The peripheral ports are made by having a machine shop bore a hole into the housing. Into this is pressed a sleeve which has an interference fit along with some industrial epoxy.
(The sleeve made out of a certain type of aluminium close to that of the housing (i.e. same thermal expansion rate), "interference fit" means that the hole is 45.00mm, while the sleeve is 45.05mm.. this ensures a very tight fit that won't move!)
The sleeve then needs to be cut off and ground back 1-2mm from the inside of the rotor housing. This avoids the apex seal being damaged or worn prematurely.
A bonus of this method is the ability to make it "look stock".. Essentially this means that the port is flush with the surface where the side housing ports are.. That is to say that the ports are in the SAME PLACE as where the water flows from the engine to the manifold. Because of this, the manifold can bolt directly onto the engine and seal the port-manifold gap with a stock manifold gasket!
(Usually the connection between the manifold and the port intake is done with a short length of radiator hose and some clamps.. yuk!!)
Limits of the engine
What are the limits of the peripheral port design? Maybe it is possible to use some big bridge ports where the original (Mazda factory) ports were. If the improvements in engine breathing can make 350hp with a street port and a peripheral port, maybe bridge ports would make 450hp??
We also thought that a peripheral port further around the housing could be used successfully with a turbo.. Just like racing beat's peripheral port turbo 900 hp 3 rotor 13G engine!!
An even weirder idea would be to put in TWO peripheral ports per housing! an intake 45mm wide x 90mm long is a mighty big port!!
Another option is to run the engine on methanol. Due to methanol's characteristics of taking heat out of the air as it evaporates, this cools the air making it denser. Denser air = higher volumetric efficiency = higher power. (a bridge port on methanol makes 250+ hp).. Perhaps it would be possible to make 500hp from a naturally aspirated engine!!
and all parts will be at cost. this dosent mean im gonna spend less it just means im gonna get a lot more for that money. im gonna go with na for now with semi p port the bellow is an extract from craigs rotary page
Peripheral port secondaries
This idea was originally created by Mazda during the mid-late 1960s with experimental engines. It was also used in Cosmo racing engines. However, as the Cosmo engine made a mere 2 horsepower more than the standard production engine the idea was not used thereafter. (This small gain is probably because of the noise restrictions placed on it, hence not being able to use a suitable exhaust system).
My friend resurrected the idea and to recently it has been used by others. Due to the sizeable intake ports - the peripheral ports are 45mm diameter plus the street ports, the volumetric efficiency is very impressive. Volumetric efficiency is a measure of the ratio of the combustion chamber size to how much air can enter the engine while the intake port is open, and in turn the more air/fuel mixture the higher the power.
In fact, this engine MAY almost be over 100%. This means that the engine takes in more air than it's capacity, which is unusual for a naturally aspirated engine - normally only turbocharged engines and highly tuned racing engines are capable of this. This explains why a peripheral port engines are high powered.
In fact, a 13B with this configuration with a Holley carburettor, electronic ignition, muffled exhaust has been dyno tested at 350 BHP ("flywheel horsepower" -calculated by the dyno)
Furthermore, due to the peripheral port secondary being a "static column of air", this tends to stop the traditional peripheral port rough idle. This is because the air is not flowing into the port, so it has a certain amount of resistance to movement or 'springiness' which limits how much of the exhaust gets around the apex seal into the fresh mixture.
Also, as the air tends to be very turbulent due to the air streams colliding, atomisation is good, resulting in a torque curve which is quite flat across the RPM range.
Given the characteristics across the RPM range, this engine combination is almost comparable to a turbo engine. It was not much more difficult to drive than a standard engine. The only problem is that this engine requires a reasonably free flowing (noisy) exhaust.
Construction of the engine
The "Mazda Factory" primary ports in the intermediate housing are filled with epoxy such as Devcon or similar, as described in the Racing Beat catalogue.
The street ports are a conventional street port. Sorry, I'm not sure of the exact port shape or timing used, but I think it was fairly close to stock to enable good low down torque (which is also boosted slightly by the relatively long induction tubes.)
The peripheral ports are made by having a machine shop bore a hole into the housing. Into this is pressed a sleeve which has an interference fit along with some industrial epoxy.
(The sleeve made out of a certain type of aluminium close to that of the housing (i.e. same thermal expansion rate), "interference fit" means that the hole is 45.00mm, while the sleeve is 45.05mm.. this ensures a very tight fit that won't move!)
The sleeve then needs to be cut off and ground back 1-2mm from the inside of the rotor housing. This avoids the apex seal being damaged or worn prematurely.
A bonus of this method is the ability to make it "look stock".. Essentially this means that the port is flush with the surface where the side housing ports are.. That is to say that the ports are in the SAME PLACE as where the water flows from the engine to the manifold. Because of this, the manifold can bolt directly onto the engine and seal the port-manifold gap with a stock manifold gasket!
(Usually the connection between the manifold and the port intake is done with a short length of radiator hose and some clamps.. yuk!!)
Limits of the engine
What are the limits of the peripheral port design? Maybe it is possible to use some big bridge ports where the original (Mazda factory) ports were. If the improvements in engine breathing can make 350hp with a street port and a peripheral port, maybe bridge ports would make 450hp??
We also thought that a peripheral port further around the housing could be used successfully with a turbo.. Just like racing beat's peripheral port turbo 900 hp 3 rotor 13G engine!!
An even weirder idea would be to put in TWO peripheral ports per housing! an intake 45mm wide x 90mm long is a mighty big port!!
Another option is to run the engine on methanol. Due to methanol's characteristics of taking heat out of the air as it evaporates, this cools the air making it denser. Denser air = higher volumetric efficiency = higher power. (a bridge port on methanol makes 250+ hp).. Perhaps it would be possible to make 500hp from a naturally aspirated engine!!
Senior Member
Joined: Jul 2003
Posts: 116
500HP on a 3Rotor ? Wow, that would sure be alot.
My worries for that sorta intake would be that the PP would over take the Primaries when they are opened. Tuning would be a interesting thou ..hehe..
How about normal throttle bodies for the primaries and secondaries with the PP being controled by a stepper motor with sliding throttle bodies. So you can tune it with the primaries and secondaries first. Than later on add the PP to the equation. It would be simplier cause then you would only need to enrich the PP injectors and not all.
It looks to be a great project. I think you need to look over to australia, cause there have been more swaps there using FB/SA22. May be they would have a engine mount there for putting a 20B in to an FB.
In any cause, please keep us informed
Love to see pics and progress
My worries for that sorta intake would be that the PP would over take the Primaries when they are opened. Tuning would be a interesting thou ..hehe..
How about normal throttle bodies for the primaries and secondaries with the PP being controled by a stepper motor with sliding throttle bodies. So you can tune it with the primaries and secondaries first. Than later on add the PP to the equation. It would be simplier cause then you would only need to enrich the PP injectors and not all.
It looks to be a great project. I think you need to look over to australia, cause there have been more swaps there using FB/SA22. May be they would have a engine mount there for putting a 20B in to an FB.
In any cause, please keep us informed
Love to see pics and progress
Senior Member
Joined: Jan 2006
Posts: 1,114
Wow, very interesting. I have heard about the Semi-PP but never had someone explain it to me in that kind of detail.
If you have connections then the 6k figure should be pretty easy to hit. There is an insane markup on many of the name brand auto parts.
Who is going to do the tuning on your car?
If you have connections then the 6k figure should be pretty easy to hit. There is an insane markup on many of the name brand auto parts.
Who is going to do the tuning on your car?
Senior Member
Joined: Oct 2003
Posts: 3,502
From: Canada
400 hours for a REW swap is excessive. I understand the work involved even fabricating everything yourself, but I can't fathom it taking remotely close to 400 hours.
I don't imagine a 20B swap would eat up that many man hours.
I don't imagine a 20B swap would eat up that many man hours.
Senior Member
Joined: May 2002
Posts: 22,465
From: California
Originally Posted by ColinRX7' post='808189' date='Mar 15 2006, 07:44 PM
400 hours for a REW swap is excessive. I understand the work involved even fabricating everything yourself, but I can't fathom it taking remotely close to 400 hours.
I don't imagine a 20B swap would eat up that many man hours.
i had over 200hours into my 20bfc swap, and then prolly another 100 or so to put the e11 into it