What's everyone's favourite port?
12-05-16, 08:47 AM
#3
Waffles - hmmm good
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When I finally make a new keg for my SA, its going to be a very aggressive port on the
secondaries and just some minor clean up on the primaries with a good amount ported on the
exhaust. Then I'll further modify my nikki to get more air/gas in the seconaries and have a very
drivable but fun motor. It will probably net me another 10-20 hp which puts me around 170
but still very driveble and with decent mileage at cruise. All 12A still.
secondaries and just some minor clean up on the primaries with a good amount ported on the
exhaust. Then I'll further modify my nikki to get more air/gas in the seconaries and have a very
drivable but fun motor. It will probably net me another 10-20 hp which puts me around 170
but still very driveble and with decent mileage at cruise. All 12A still.
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12-05-16, 07:25 PM
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When I finally make a new keg for my SA, its going to be a very aggressive port on the
secondaries and just some minor clean up on the primaries with a good amount ported on the
exhaust. Then I'll further modify my nikki to get more air/gas in the seconaries and have a very
drivable but fun motor. It will probably net me another 10-20 hp which puts me around 170
but still very driveble and with decent mileage at cruise. All 12A still.
secondaries and just some minor clean up on the primaries with a good amount ported on the
exhaust. Then I'll further modify my nikki to get more air/gas in the seconaries and have a very
drivable but fun motor. It will probably net me another 10-20 hp which puts me around 170
but still very driveble and with decent mileage at cruise. All 12A still.
10-20hp doesn't sound like much but in these light rx7s you will feel a difference.
12-05-16, 07:27 PM
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12-05-16, 07:31 PM
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12-07-16, 12:34 AM
#14
Yes, and it was the stock size of the secondaries in T2, Cosmo and FD engines. It opens at the same time as a stock 12A but closes 10 degrees later at 50 degrees.
stock 12A 40 degrees closing (stock)
74 spec 50 degrees closing (perfect for the street for NA and boost)
RB streetport 60 degrees closing (with earlier opening, is peaky, loses low end torque, only good for track use at high RPM)
stock 12A 40 degrees closing (stock)
74 spec 50 degrees closing (perfect for the street for NA and boost)
RB streetport 60 degrees closing (with earlier opening, is peaky, loses low end torque, only good for track use at high RPM)
12-07-16, 07:33 PM
#20
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I'm getting old and boring and my next engine is going to be a stock port 12A. I had to drive a customer's MGB for a bit and I miss having a simple and low performance car. Now if only there was a way to put a Laycock de Normanville overdrive on a Mazda 4-speed 
(Yes, I know there IS a way, you use a Volvo transmission because people in Scandinavian countries put Volvo trannys behind damn near everything)
(Yes, I know there IS a way, you use a Volvo transmission because people in Scandinavian countries put Volvo trannys behind damn near everything)
12-07-16, 10:44 PM
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I'm getting old and boring and my next engine is going to be a stock port 12A. I had to drive a customer's MGB for a bit and I miss having a simple and low performance car. Now if only there was a way to put a Laycock de Normanville overdrive on a Mazda 4-speed
(Yes, I know there IS a way, you use a Volvo transmission because people in Scandinavian countries put Volvo trannys behind damn near everything)
(Yes, I know there IS a way, you use a Volvo transmission because people in Scandinavian countries put Volvo trannys behind damn near everything)
plus the top goes down.
on the minus side, it made the Lancia Scorpion feel like a space ship.
12-08-16, 12:43 PM
#22
j9fd3s told me to build my MG's next rotary engine for torque. So for me that translates to a stock 40 degree 12A spec set of ports with only smoothing performed, to get rid of the sharp 90 degree edges, which arguably are good for introducing turbulence, but it just seems kind of wrong to not give it a port cleanup; at this point at least, so I did. In my 74 spec ported Y and R5 engines, the smoothing always works well in them so I gave it a shot here on the stockers.
Really really big Nikki. I don't know if this is the right way to go here, but with no turbo option in this car, not that one is even needed hahaha, but because I'm at the mercy of the atmosphere and how much vacuum the engine can produce, I need to go big or go home, carb-wise.
Direct fire. Obviously. More power everywhere. Better drivability. It just plain works better than stock cap'n rotor stuff.
Free flowing exhaust such as a copy of the RB long primary should work here. I've found that the long primary gives more power everywhere from low RPM to high compared with a short collected. So I painstakingly fabbed one up for this car consisting of two 2" RB presilencers, two 2" Magnapacks, then collected to 2.5" into a single long 2.5" Magnapack.
As for perceived low end torque, you don't want a heavy or light flywheel in here. The rotary gods are telling me to just keep it simple and go with an RB light steel flywheel. The car itself is so small and light that I could get away with aluminum, but I don't feel like aluminum is the right choice here. I want a low strung, easy to drive car.
The last time I drove this, it only made maybe 70HP and was pretty nice, despite the secondaries not flowing in the carb. This new setup is expected to take a stock 76 Cosmo 110HP old school 13B architecture and raise it to about 140HP which sounds quite reasonable considering all the upgrades it's getting (only adding about 30HP). This effectively doubles what it had before. So even though I'm not doing my most favorite port size here, I think this is the right path to take on this one unique vehicle.
Way too many noobs make the rookie mistake of huge ports, too light flywheels, a heavy effort pressure plate that is not needed, puck clutch, loud poorly constructed exhausts like straight pipes, and they wonder why their stock grocery getter gets driven more. Well duh.
In my 74 spec ported Y and R5 engines, the smoothing always works well in them so I gave it a shot here on the stockers.Really really big Nikki. I don't know if this is the right way to go here, but with no turbo option in this car, not that one is even needed hahaha, but because I'm at the mercy of the atmosphere and how much vacuum the engine can produce, I need to go big or go home, carb-wise.
Direct fire. Obviously. More power everywhere. Better drivability. It just plain works better than stock cap'n rotor stuff.
Free flowing exhaust such as a copy of the RB long primary should work here. I've found that the long primary gives more power everywhere from low RPM to high compared with a short collected. So I painstakingly fabbed one up for this car consisting of two 2" RB presilencers, two 2" Magnapacks, then collected to 2.5" into a single long 2.5" Magnapack.
As for perceived low end torque, you don't want a heavy or light flywheel in here. The rotary gods are telling me to just keep it simple and go with an RB light steel flywheel. The car itself is so small and light that I could get away with aluminum, but I don't feel like aluminum is the right choice here. I want a low strung, easy to drive car.
The last time I drove this, it only made maybe 70HP and was pretty nice, despite the secondaries not flowing in the carb. This new setup is expected to take a stock 76 Cosmo 110HP old school 13B architecture and raise it to about 140HP which sounds quite reasonable considering all the upgrades it's getting (only adding about 30HP). This effectively doubles what it had before. So even though I'm not doing my most favorite port size here, I think this is the right path to take on this one unique vehicle.
Way too many noobs make the rookie mistake of huge ports, too light flywheels, a heavy effort pressure plate that is not needed, puck clutch, loud poorly constructed exhausts like straight pipes, and they wonder why their stock grocery getter gets driven more. Well duh.
