1974 FBP turbo REPU and turbo rotary sandrail
01-30-13, 12:49 PM
#1
1974 FBP turbo REPU and turbo rotary sandrail
the REPU was mine for about 5 years until last year when i sold it to a local customer, who had similar plans for it as what i had intended, with the exception of the rat rod scheme clear coating over the original paint.. 
bed was Line-X'd as well as the interior floor pans which were replaced with new steel.
the engine was rebuilt with a spare '74 13B block i had for parts, 3B castings, full bridged- press in exhaust sleeves removed. turbo is a turbonetics, unknown to me size ceramic BB center(size looks to be about TO4E equivalent). carb is a holley 500cfm 2 barrel blowthrough. ignition is a MSD6BTM running leading only with boost retard and rev limiter. oil pump is overdriven, stat gears and e-shaft replaced with updated parts.
the rail is a custom built one by an unknown to me shop, the rear rotor was blown so the engine came out and was rebuilt with a stock port. haltech E6x with stock series 5 turbo.
pictures say a thousand words, so here you go.
bed was Line-X'd as well as the interior floor pans which were replaced with new steel. the engine was rebuilt with a spare '74 13B block i had for parts, 3B castings, full bridged- press in exhaust sleeves removed. turbo is a turbonetics, unknown to me size ceramic BB center(size looks to be about TO4E equivalent). carb is a holley 500cfm 2 barrel blowthrough. ignition is a MSD6BTM running leading only with boost retard and rev limiter. oil pump is overdriven, stat gears and e-shaft replaced with updated parts.
the rail is a custom built one by an unknown to me shop, the rear rotor was blown so the engine came out and was rebuilt with a stock port. haltech E6x with stock series 5 turbo.
pictures say a thousand words, so here you go.
Last edited by RotaryEvolution; 01-30-13 at 01:00 PM.
01-30-13, 01:52 PM
#3
those things are really in there, i miss the old(new-er) roll pins!
left the original block unmolested and in one piece to shelf it. a little bit of rotary history being the first year of the 13B engine, well one off from the 4 in '73.
left the original block unmolested and in one piece to shelf it. a little bit of rotary history being the first year of the 13B engine, well one off from the 4 in '73.
Last edited by RotaryEvolution; 01-30-13 at 01:56 PM.
01-30-13, 04:09 PM
#5
Yeah, had two complete sets and a partial set of 3B irons. Also had two sets of 98 to 99 % perfect chrome housings. Also happen to have two 74 REPUs.
But I decided to go with more modern nitrided J-spec R5 side plates and rotor housngs. These just need a port job out to 74 spec. The exhaust ports are already at GSL-SE spec so are better for low end torque as it slightly delays the opening to give more time for gasses to push on the eccentric shaft. This beneficial effect starts to be less beneficial past 4k, but when you're looking for low end, you're more concerned with RPMs at less than 4k. High end exhaust flow is like any GSL-SE engine, so there's that.
But I decided to go with more modern nitrided J-spec R5 side plates and rotor housngs. These just need a port job out to 74 spec. The exhaust ports are already at GSL-SE spec so are better for low end torque as it slightly delays the opening to give more time for gasses to push on the eccentric shaft. This beneficial effect starts to be less beneficial past 4k, but when you're looking for low end, you're more concerned with RPMs at less than 4k.
High end exhaust flow is like any GSL-SE engine, so there's that.
01-30-13, 04:15 PM
#6
for now it has no airflow across the IC while it is being broken in, no need. there was an electric fan mounted on top which i will tell him needs to be reinstalled later on. bounced around ideas of a front mount but this seemed to work and adds to the sleeper status, while the bridge really detracts from it...
i don't mess much with the FB stuff much, still a severe lack of interest in the 1st gen engines for me to bother with them. most people restore them on their own. the irons will be ok, they were a near perfect set i had with almost zero step wear and this truck won't be raced or see that many miles. he just wanted something that would get out of it's own way versus the pinky finger tight OE porting and the turbo to give it a little extra. probably will be about 300 to the wheel(told him he should look into an LSD but he still sais he wants to leave it alone) all said and done at sub 10psi. still has the 4.70 rear with 4 speed so gearing and torque aren't an issue. at one point the truck had a camper on it, the brackets are still welded to the frame. with the high compression and smaller trim turbo it probably makes well over twice the original bottom end anyways.
i don't mess much with the FB stuff much, still a severe lack of interest in the 1st gen engines for me to bother with them. most people restore them on their own. the irons will be ok, they were a near perfect set i had with almost zero step wear and this truck won't be raced or see that many miles. he just wanted something that would get out of it's own way versus the pinky finger tight OE porting and the turbo to give it a little extra. probably will be about 300 to the wheel(told him he should look into an LSD but he still sais he wants to leave it alone) all said and done at sub 10psi. still has the 4.70 rear with 4 speed so gearing and torque aren't an issue. at one point the truck had a camper on it, the brackets are still welded to the frame. with the high compression and smaller trim turbo it probably makes well over twice the original bottom end anyways.
Last edited by RotaryEvolution; 01-30-13 at 04:23 PM.
01-30-13, 05:12 PM
#7
A T04E should do well in these trucks. I recently got a T04B for mine. Just a cheap eBay thing, but all it needs is twice its stock power to make me happy.
Stock power output of the REPU was:
110HP at 6000
117 torque at 3500
For some reason they didn't list the torque at 4k where all other rotaries from the 76 Cosmo and up were listed. Weird.
I figure with the turbo I could do 220HP without much trouble. Probably 14psi or less. So that means I can run pump gas.
Still not sure about a front mount IC. Any ideas? Think it will need to be custom made to fit down in front of the oil cooler?
What about water injection?
Stock power output of the REPU was:
110HP at 6000
117 torque at 3500
For some reason they didn't list the torque at 4k where all other rotaries from the 76 Cosmo and up were listed. Weird.
I figure with the turbo I could do 220HP without much trouble. Probably 14psi or less. So that means I can run pump gas.
Still not sure about a front mount IC. Any ideas? Think it will need to be custom made to fit down in front of the oil cooler?
What about water injection?
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01-30-13, 06:13 PM
#8
i wouldn't run it that high on these higher compression engines, 12psi and below should be fine on them though running pump gas.
didn't want to go with AI, i already have to jab him with a stick to premix so i wouldn't have to setup the OMP to adapt to the holley linkage.
didn't want to go with AI, i already have to jab him with a stick to premix so i wouldn't have to setup the OMP to adapt to the holley linkage.
01-31-13, 12:48 AM
#12
Ah, yes. I've got an S4 NA assembly I'd like to use in mine. I like the 24 pound flywheel in a vehicle this heavy.
Think the 9.4 compression ratio is going to be a real problem without an intercooler? I honestly don't want to run any kind of aux injection either. Heck I'll do anything to keep using the OMP!
How much boost do you think it would take to make 220HP?
Think the 9.4 compression ratio is going to be a real problem without an intercooler? I honestly don't want to run any kind of aux injection either. Heck I'll do anything to keep using the OMP!
How much boost do you think it would take to make 220HP?
01-31-13, 12:07 PM
#13
i would run an intercooler if you are running pump gas, these engines already run hot so not worth possibly ruining an engine on a hot day even with only a few psi of boost.
the TO4B should do 220whp at about 5-6psi on the later series block, might take a little more if it was the original rotor housings with tiny exhaust ports.
the TO4B should do 220whp at about 5-6psi on the later series block, might take a little more if it was the original rotor housings with tiny exhaust ports.
01-31-13, 05:08 PM
#15
I gotcha. The reason I didn't want to run an intercooler, aside from the extra complexity, piping etc, is because PercentSevenC got away without an intercooler up to 10psi on a similar engine setup. He had 9.2 CR rotors and an otherwise nearly identical engine to mine except mine will have 9.4 rotors.
He had an S5 turbo with just an increased wastegate travel (we ground some iron from the rear plate so it could open further). The carb was a weber 45 DCOE. The engine was a streetported nitrided R5 with 3mm Atkins apex seals. Full 3" exhaust. He started with stock wastegate pressure, then added a manual boost controller and got it up to 10psi. locked dizzy, direct fire, 92 octane pump gas. We estimated it made around 200HP at 10psi. And its low end torque was amazing because it could spool pretty much right at idle.
I wanted this turbo setup for my REPU for the obvious low end spool. But it's his and he still needs it for his new engine. So I looked around for months until I found a cheap aftermarket turbo with similar features.
I mention this because I just ran the numbers on my turbo and discovered it has the same hot vs cold wheel area percentage as a T2 using Howard Coleman's formula.
.................................................. ........cold.......................hot............ ........relationship
FC T2 (OEM)........................................3.579 ....................4.288...................119
T04B.............................................. ....4.764....................5.708................ ...119
They're both 119%!
Notice both wheels of the aftermarket are bigger? I am a little concerned with lag, but not much.
I figure if I could recreate the conditions found in Percent's setup, and just run it at 5 to 6psi or, it'll get me to there without an intercooler, but like you said, it's not worth risking my nice new engine. I'll look around for a short wide core that can fit down in the oil cooler area or maybe more like the one you have pictured.
I know what you're talking about regarding exhaust ports. Mine are actually the same exact sleeves and port timing as a GSL-SE, so all I need to do is port them down a little to match a T2/FD and that should be all I need. Well, also go wider 2mm if I remember right. I've got some FC and FD housings here to look at.
He had an S5 turbo with just an increased wastegate travel (we ground some iron from the rear plate so it could open further). The carb was a weber 45 DCOE. The engine was a streetported nitrided R5 with 3mm Atkins apex seals. Full 3" exhaust. He started with stock wastegate pressure, then added a manual boost controller and got it up to 10psi. locked dizzy, direct fire, 92 octane pump gas. We estimated it made around 200HP at 10psi. And its low end torque was amazing because it could spool pretty much right at idle.
I wanted this turbo setup for my REPU for the obvious low end spool. But it's his and he still needs it for his new engine. So I looked around for months until I found a cheap aftermarket turbo with similar features.
I mention this because I just ran the numbers on my turbo and discovered it has the same hot vs cold wheel area percentage as a T2 using Howard Coleman's formula.
.................................................. ........cold.......................hot............ ........relationship
FC T2 (OEM)........................................3.579 ....................4.288...................119
T04B.............................................. ....4.764....................5.708................ ...119
They're both 119%!
Notice both wheels of the aftermarket are bigger? I am a little concerned with lag, but not much.
I figure if I could recreate the conditions found in Percent's setup, and just run it at 5 to 6psi or, it'll get me to there without an intercooler, but like you said, it's not worth risking my nice new engine. I'll look around for a short wide core that can fit down in the oil cooler area or maybe more like the one you have pictured.
I know what you're talking about regarding exhaust ports.
Mine are actually the same exact sleeves and port timing as a GSL-SE, so all I need to do is port them down a little to match a T2/FD and that should be all I need. Well, also go wider 2mm if I remember right. I've got some FC and FD housings here to look at.
02-01-13, 05:21 PM
#19
i'm sure you can get away without the intercooler but i would say 10psi is rather pushing it with that compression ratio, add in hot ambient temps and it may wind up costing him.
the sandrail will easily pull wheelies, already got the front end light just off idle with the rather touchy 6 puck clutch. never went over a few pounds of boost on the street though and the front end isn't really setup fot street driving with the aggressive toe in so i wasn't out to see what it would do. if the engine was broken in i bet it would pull up once boost really kicked in, the engine subframe would act as a wheelie bar also basically limiting you to a 90* angle. all the weight is in the back, the front end actually can be lifted easy by 1 person weighing about 100lbs unloaded(no passengers, since the engine actually pulls weight off the front). weight ratio is probably about 25/75 front/rear without passengers.
the sandrail will easily pull wheelies, already got the front end light just off idle with the rather touchy 6 puck clutch. never went over a few pounds of boost on the street though and the front end isn't really setup fot street driving with the aggressive toe in so i wasn't out to see what it would do.
if the engine was broken in i bet it would pull up once boost really kicked in, the engine subframe would act as a wheelie bar also basically limiting you to a 90* angle. all the weight is in the back, the front end actually can be lifted easy by 1 person weighing about 100lbs unloaded(no passengers, since the engine actually pulls weight off the front). weight ratio is probably about 25/75 front/rear without passengers.
Last edited by RotaryEvolution; 02-01-13 at 05:28 PM.
02-02-13, 09:21 PM
#22
talking head
FYI.. for the old body utes ,,,a thick chaser 1jz cooler fits in the left front guard
( in front of the wheel ) with plenty of space and convenient outlet positions to allow the cross under pipe to hide under the lower valence panel
a couple of 50 mm holes in the valence panel behind the bumper is completely stealthly and works well .. no need for bonnet scoops or obvious front mount with grill mods
( in front of the wheel ) with plenty of space and convenient outlet positions to allow the cross under pipe to hide under the lower valence panel
a couple of 50 mm holes in the valence panel behind the bumper is completely stealthly and works well .. no need for bonnet scoops or obvious front mount with grill mods
02-02-13, 10:56 PM
#24
talking head
all i have is bay and engine build pics and i neglected to take any of the IC mounted up in the wheel well
( its mounted in a similar location on the chaser BTW )
the car itself back comes through regularly and im currently building up a turbo for it so i will try and remember to take a pic or two when it does
its a daily user and has been for a couple of years like this so you can rest happy there has been no issue with anything whacking it under there
( its mounted in a similar location on the chaser BTW )
the car itself back comes through regularly and im currently building up a turbo for it so i will try and remember to take a pic or two when it does
its a daily user and has been for a couple of years like this so you can rest happy there has been no issue with anything whacking it under there