Header fixed
08-21-2008, 12:05 AM
#1
1.0 BAR
Thread Starter
Join Date: May 2006
Posts: 264
Header fixed
Hey I have this header on my FB Rx-7 that collects two 1-7/8" id primarys in to a 2" id pipe that has been all cut up and bastardised. I want to cut off the 2" and collect them into .125 wall 2.25 id instead. I've got a new flange and I just need the 1/8" wall 2.25"id pipe. Anyone know where I could get about 1' of that pipe and anyone want to help me cut it up and weld it up? I know there are a few out here in WA that are quite crafty with a welder and your bad *** HMT cars. I'm in Seattle BTW. Cash in hand. Any help would be great.
08-21-2008, 01:36 AM
#5
1.0 BAR
Thread Starter
Join Date: May 2006
Posts: 264
Re: Header fixed
Actually...A true dual setup is only when the primaries are not collected at all. True duals only work on stock ported engines. a stock rotary has huge amounts of over lap. A stock port has as much over lap as compairable to running 278 cams on a boinger. The bigger the ports the more potential power and the more overlap. My car has a fully built 13B with huge ports. When building a powerfull rotary you want to get the exhaust out as fast as possible. The best way to do this is with exhaust scavenging, in laymans turns a collected exhaust scavenges the exhaust pulses. You collect a rotaries exhaust depending on how big your ports are and where you want to have peak torque. Long primary exhausts as you suggested will make peak tq from 4-5K depending on port and where you collect. any where between 89 and 125 inches depenging on induction flow rates and port size. Short primary exhausts as I have usually make peak TQ from 6-10k again depenging on induction flow rates and port size and type. These short primary exhausts usually collect from 10 to 25 inches. The longer the primaries the lower Rpm the engine will make peak tq. Mine already collect at 25" and should be perfect for my port size and power goals, but it's just a shitty collector that needs to be redone. Sorry for the book but I know my rotors I've built plenty of very high HP rotaries throughout my years. I even have tought rotaries in auto engineering classes.
08-21-2008, 01:52 AM
#6
3.0 BAR
Join Date: Sep 2003
Posts: 5,448
Re: Header fixed
Originally Posted by hyper4mance2k
Actually...A true dual setup is only when the primaries are not collected at all. True duals only work on stock ported engines. a stock rotary has huge amounts of over lap. A stock port has as much over lap as compairable to running 278 cams on a boinger. The bigger the ports the more potential power and the more overlap. My car has a fully built 13B with huge ports. When building a powerfull rotary you want to get the exhaust out as fast as possible. The best way to do this is with exhaust scavenging, in laymans turns a collected exhaust scavenges the exhaust pulses. You collect a rotaries exhaust depending on how big your ports are and where you want to have peak torque. Long primary exhausts as you suggested will make peak tq from 4-5K depending on port and where you collect. any where between 89 and 125 inches depenging on induction flow rates and port size. Short primary exhausts as I have usually make peak TQ from 6-10k again depenging on induction flow rates and port size and type. These short primary exhausts usually collect from 10 to 25 inches. The longer the primaries the lower Rpm the engine will make peak tq. Mine already collect at 25" and should be perfect for my port size and power goals, but it's just a shitty collector that needs to be redone. Sorry for the book but I know my rotors I've built plenty of very high HP rotaries throughout my years. I even have tought rotaries in auto engineering classes.
i just read books and talk to jim downing. his shop is right down the street from my house.
08-21-2008, 02:23 AM
#9
1.0 BAR
Thread Starter
Join Date: May 2006
Posts: 264
Re: Header fixed
lol nice coments. This site is always good for the post -----s. Jim is a good guy, really knows his ----. I wish he'd get back into it like he was in the 80's. I'd love to see some new ---- from them.
