FD in REPU. What?
11-12-10, 01:25 AM
#1
FD in REPU. What?
Can it be done? Does the upper manifold (TB with elbow) fit? Will the twins fit? Yes and no.
Has anyone ever installed an actual FD setup in their REPU before? I'm talking about REAL genuine rotary trucks from '74-'77 here. Oh sure the keg will bolt in like any other 13B with a front cover and oil pan swap, but what about the FD-specific manifolding and stuff? My guess is nope.
So far I've test fitted the LIM and UIM with stock TB and it does all fit, but a Cosmo elbow (no FD elbow handy) hits the brake booster. There are ways around that like cut and weld a greddy elbow to make it narrower. Or if you're hard core and don't care about pressure wave tuning, or tuned length (whatever Mazda's engineers had in mind when they designed the FD UIM) you could chop out an inch or two to move the TB away from the brake booster.
Then you have the throttle cable issue. FD pulls from the other side but there is another throttle lever on our side that could be made to work with the stock REPU cable... maybe. I don't like the sharp angle it takes.
Then there is the stock FD waterpump which allows the stock secondary injector rail to fit. I tested it with an S4 waterpump (to possibly keep the clutch fan because it's a truck) and it hits the injector rail banjo bolt. I'm not too up on aftermarket rails and their lengths, but I'm sure they were all designed with an FD waterpump in mind so probably no help for me. I'd have to run an FD waterpump regardless. So electric fan time for me.
The rear plate water temp sensor has a BSP thread instead of a straight thread. Mazdatrix says the BSP temp sender (with a bullet connector) to fit newer rear plates in FBs will read incorrectly in early chassis. I'd need an aftermarket gauge.
I already test fitted the stock twins. I could physically fit them in a 77 REPU because the frame rails have a nice 45° section right where the wastegates are. No luck for that in a 74. Also the downpipe would have to exit right out into the upper A-arm. You'd have to get really creative to route the downpipe up and away from the suspension stuff while keeping away from the Y pipe and the rear turbo's air intake pipe. Stock twins are a no go. A custom divided T4 manifold and some sort of aftermarket single turbo is the best choice.
It's kind of funny that I actually have a nearly complete old school 4 port R5 13B ready to go. Just needs 3 apex seals and porting out to 74 spec (to match the truck's year). Already have the gasket set, all rotor springs, clutch, fresh GSL-SE flywheel etc. I also have a 7" Camden and a nearly complete long primary exhaust just aching to go in (just needs one Magnaflow 5x8). The ironic part is I could build the FD keg instead and use the Camden and exhaust on it the same with a simple intake manifold swap (to fit FD bolt pattern) until I'm ready to go EFI and turbo. I would not have this option if I went with the R5 engine. With the R5, I'd be locked into the somewhat limited potential of a Camden, or go blow through turbo with a weber and fight with it constantly (tune it) as PercentSevenC is doing right now to solve a misfire above 5k in boost. Could be ignition. Who knows as it doesn't seem to show up on his wideband. Not to mention it goes pig rich at highway cruising (the achilles heel of blow through, apparently). I'd prefer the tuning of EFI when it comes right down to it, or run a 4 bbl carb atop a Camden and not think about it constantly.
So what should I do? Save the FD setup for another project? 1st gen maybe? Do the R5 in the REPU instead? The R5 is massively cheaper for me to build, and it would be reliable and provide maybe up to 170HP if everything else is set up right. Remember, Camdens like being on stock or nearly stock ports. When 84stock ran his bridgeported engine, all the Camden did was smooth out the idle. Then he over reved it and shelled the peanuts (cracked the camden rotors due to contact). I've got a centerforce pressure plate and stock clutch disc that will handle a Camden, but not a turbo. My ignition is strong enough for a Camden but not a turbo (maybe). My cooling system handled a Camden just fine last year with a clutch fan. I'm a little hesitant to switch to an electric fan. I know, opposite of most who will read this. My fuel system is already set up for a Camden but not a turbo.
R5 is what I'm now thinking I'll go with. If I went with FD, its stock output of 255 at the flywheel would require a stronger clutch than what I'm interested in using as a daily driver in the stock 225mm size. I'd have to run at least an RB street strip set up, or maybe an Exedy stage 1 10806 (ask kentetsu or bwaits how they like it) or an ACT HD pressure plate with street disc (full face organic with limited marcels). Why you ask? Because the REPU tranny is a ribcase similar to the T2 so I see no need to upgrade, but can only go up to 225mm, not 235 or 240mm. So either lower power, or stonger pressure plate. Pick one.
Oh blwfly, I test fitted an FC collected header in the 77 today. Part of it hit the tranny crossmember. It may clear a 74 as those were further forward.
Has anyone ever installed an actual FD setup in their REPU before? I'm talking about REAL genuine rotary trucks from '74-'77 here. Oh sure the keg will bolt in like any other 13B with a front cover and oil pan swap, but what about the FD-specific manifolding and stuff? My guess is nope.
So far I've test fitted the LIM and UIM with stock TB and it does all fit, but a Cosmo elbow (no FD elbow handy) hits the brake booster. There are ways around that like cut and weld a greddy elbow to make it narrower. Or if you're hard core and don't care about pressure wave tuning, or tuned length (whatever Mazda's engineers had in mind when they designed the FD UIM) you could chop out an inch or two to move the TB away from the brake booster.
Then you have the throttle cable issue. FD pulls from the other side but there is another throttle lever on our side that could be made to work with the stock REPU cable... maybe. I don't like the sharp angle it takes.
Then there is the stock FD waterpump which allows the stock secondary injector rail to fit. I tested it with an S4 waterpump (to possibly keep the clutch fan because it's a truck) and it hits the injector rail banjo bolt. I'm not too up on aftermarket rails and their lengths, but I'm sure they were all designed with an FD waterpump in mind so probably no help for me. I'd have to run an FD waterpump regardless. So electric fan time for me.
The rear plate water temp sensor has a BSP thread instead of a straight thread. Mazdatrix says the BSP temp sender (with a bullet connector) to fit newer rear plates in FBs will read incorrectly in early chassis. I'd need an aftermarket gauge.
I already test fitted the stock twins. I could physically fit them in a 77 REPU because the frame rails have a nice 45° section right where the wastegates are. No luck for that in a 74. Also the downpipe would have to exit right out into the upper A-arm. You'd have to get really creative to route the downpipe up and away from the suspension stuff while keeping away from the Y pipe and the rear turbo's air intake pipe. Stock twins are a no go. A custom divided T4 manifold and some sort of aftermarket single turbo is the best choice.
It's kind of funny that I actually have a nearly complete old school 4 port R5 13B ready to go. Just needs 3 apex seals and porting out to 74 spec (to match the truck's year). Already have the gasket set, all rotor springs, clutch, fresh GSL-SE flywheel etc. I also have a 7" Camden and a nearly complete long primary exhaust just aching to go in (just needs one Magnaflow 5x8). The ironic part is I could build the FD keg instead and use the Camden and exhaust on it the same with a simple intake manifold swap (to fit FD bolt pattern) until I'm ready to go EFI and turbo. I would not have this option if I went with the R5 engine. With the R5, I'd be locked into the somewhat limited potential of a Camden, or go blow through turbo with a weber and fight with it constantly (tune it) as PercentSevenC is doing right now to solve a misfire above 5k in boost. Could be ignition. Who knows as it doesn't seem to show up on his wideband. Not to mention it goes pig rich at highway cruising (the achilles heel of blow through, apparently). I'd prefer the tuning of EFI when it comes right down to it, or run a 4 bbl carb atop a Camden and not think about it constantly.
So what should I do? Save the FD setup for another project? 1st gen maybe? Do the R5 in the REPU instead? The R5 is massively cheaper for me to build, and it would be reliable and provide maybe up to 170HP if everything else is set up right. Remember, Camdens like being on stock or nearly stock ports. When 84stock ran his bridgeported engine, all the Camden did was smooth out the idle. Then he over reved it and shelled the peanuts (cracked the camden rotors due to contact). I've got a centerforce pressure plate and stock clutch disc that will handle a Camden, but not a turbo. My ignition is strong enough for a Camden but not a turbo (maybe). My cooling system handled a Camden just fine last year with a clutch fan. I'm a little hesitant to switch to an electric fan. I know, opposite of most who will read this. My fuel system is already set up for a Camden but not a turbo.
R5 is what I'm now thinking I'll go with. If I went with FD, its stock output of 255 at the flywheel would require a stronger clutch than what I'm interested in using as a daily driver in the stock 225mm size. I'd have to run at least an RB street strip set up, or maybe an Exedy stage 1 10806 (ask kentetsu or bwaits how they like it) or an ACT HD pressure plate with street disc (full face organic with limited marcels). Why you ask? Because the REPU tranny is a ribcase similar to the T2 so I see no need to upgrade, but can only go up to 225mm, not 235 or 240mm. So either lower power, or stonger pressure plate. Pick one.
Oh blwfly, I test fitted an FC collected header in the 77 today. Part of it hit the tranny crossmember. It may clear a 74 as those were further forward.
11-12-10, 01:39 AM
#2
Jolly Green Giant
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Not sure how much help these pics will be but two REPUs I remember from Speedhunters both with REW swaps [or at the very least intakes] but as well are both singles.
11-12-10, 02:33 PM
#5
jeff i had to do a small notch on my tranny crossmember it apears the large tube between the frame rails may be a tad in the way to. nothing a little cut to the header and weld would fix
i think you would be better off building the r5 with a camden.
sounds to me you dont want to spend the money to go efi and turbo with a rew.
but in the long run the search for power you would apreciate the rew setup with a single.
i think you would be better off building the r5 with a camden.
sounds to me you dont want to spend the money to go efi and turbo with a rew.
but in the long run the search for power you would apreciate the rew setup with a single.
