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Okay, so I just picked up a 1987 Toyota Supra. It was a turbo model. It has the vaunted r154. And is the perfect candidate? To accept a modern V8. So seeing as how I am normally a Mopar, man. And have a engine shop machine shop. And have a 575 horsepower G3 Hemi at my beckon call. And have an ax15 bellhousing. I have decided to take the plunge and turn my Mark 3. Into a road racing fire breathing late night late 80s supercar. The intention is to Road Track this car or road races car? At calibogue earn my high performance Driving Experience license. Autocross, etc, etc. By the way, my name is Jesse. Also known as J.Rob
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Discussion Starter #2
Also, I need to reach out to the Supra community. And I need some help with the wiring. Succinctly, I need a Mark 3 1986 and a half to 1987. Wiring schematic diagram manual so on and so forth something. That I can figure out how to rewire this screwed-up project. J.Rob
 

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this is a cool project imho. is the hemi a smaller narrow v8?

but the trans and rear end (for that matter) are wrong for all that low end torque / rotating assembly weight and shock

r154 holds 600 hp of jz because its coming on high in the rpm. lower torque but at a higher rpm

that monster hemi has to be the opposite. loads of torque at way lower rpm.

not a mopar guy ...but isn't there a better trans that bolts to that engine from the factory ?
 

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Discussion Starter #6
this is a cool project imho. is the hemi a smaller narrow v8?

but the trans and rear end (for that matter) are wrong for all that low end torque / rotating assembly weight and shock

r154 holds 600 hp of jz because its coming on high in the rpm. lower torque but at a higher rpm

that monster hemi has to be the opposite. loads of torque at way lower rpm.

not a mopar guy ...but isn't there a better trans that bolts to that engine from the factory ?
I appreciate the advice but my G3 hemi isnt all that torquey. It makes 570hp @ 7200 rpm and 480tq @ 5300 rpm which is not exactly low end. J.Rob
 

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isnt a 6 speed tremic ~$2500

this has to be be stronger / better shifting no ? ( again not a dodge guy)

r154 does have upgrade parts available. you can even buy new units from driftmotion. I just think that v8 has a whole lot more oomph when the clutch is coming out vs a 3L six.

I like the rpm that motor can spin -- this should be interesting
 

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Discussion Starter #10
isnt a 6 speed tremic ~$2500

this has to be be stronger / better shifting no ? ( again not a dodge guy)

r154 does have upgrade parts available. you can even buy new units from driftmotion. I just think that v8 has a whole lot more oomph when the clutch is coming out vs a 3L six.

I like the rpm that motor can spin -- this should be interesting
I have a pretty deep understanding of hp and tq. I own and operate a machine shop with a dyno. I'm not a guy to bolt 9" slicks o this and dump the clutch h at 5500 rpm at a glued dragstrip. I'm looking forward to Calabogie time. J.Rob
 

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That's a nice looking 87 - it picked up 89+ mirrors and trim at some point too, but kept the 87-88 front bumper. Perfect!

Having worked on a decent number of modern Mopars when I still worked in the performance industry, there's a few things that immediately come to mind.
First, oil pan and oil filter housing clearance in the MK3 subframe. We did a 6.1L crate Hemi swap into a 71 Challenger and clearance of all that stuff was a nightmare. There are very few alternate designs from other applications to swap to and a dry sump is a shitload of money. I'd mock that part up and figure out mounts, bell housing clearance and firewall clearance etc to get the engine as far back as possible for better weight distro, considering your intended goal.
Also consider header clearance with the steering shaft, etc. The further back you get the motor in the engine bay, the less that sucks, but the more you'll likely have to fuck with the oil pan, etc.

Second, get a TR6060 from a wrecked Challenger and live happily ever after. There is absolutely no sense fucking around with an R154 and a custom pilot bearing chingus and all that bullshit for the shifter, ratios, etc that you get with an R154. Sell the R154 for $800-1000 to offset the cost of the TR6060 and live happily ever after. Yes, shifter location will take some fuckery and yes you'll need a custom driveshaft and all that but the common rear end ratios available for a MK3 will be an excellent range from which to pick, and you'll want a lightweight 1-pc driveshaft anyway given your purposes.

Wiring wise, follow the TSRM's but given the way Mopar PCM's are set up these days you'll basically be running all Mopar wiring and ECU and simply integrating it into your main ignition power, etc. You will probably want to get the OE fuel pump from an SRT8 or Hellcat and use the Mopar's PCM to run that with PWM since all that shit is set up as a returnless fuel system and that's a clusterfuck to get around and keep the Mopar PCM happy especially if it's newer than 2015 or so. You'll likely have to get creative with FP control wiring and the fuel line as well. I would recommend finding a small charcoal canister, relocating it to under the rear of the car somewhere, and venting it to atmosphere to relieve excess tank pressure, and capping off the return line entirely.

Gauges will be interesting - you could use the 7M's coolant temp sender and oil pressure sender to keep those gauges, the gas gauge would be fine too, but Tach and VSS will be a bitch because the tach is straight coil pack driven and the VSS is cable-driven in the MK3, and the Mopar PCM runs both tach and VSS gauge output as CAN bus shit if memory serves. You might be able to rig a tach signal from one of the coil packs, and get a VSS input for an aftermarket gauge from an ABS hall sensor with a Dakota digital VSS box to adjust it to match speed, but that doesn't fix the speedo itself in the MK3 cluster being cable driven.

Personally, having laid hands on Coyote 5.0L's, Chevy LS's, and Mopar Hemis of all modern flavors - I think the Hemi swap will be significantly more difficult, expensive, and complicated than an LS without any tangibly superior results for your goals. You will have far wider parts support, different OE options for custom configurations in accessory config, belt drive, intake manifolds, oil pans, headers, cams, etc with an LS and you'll have equivalent if not superior configuration that's easier to tune and has a vastly more flexible factory PCM that can easily be re-tuned to accommodate swap fuckery than the Mopar PCM.

Beyond all that, building a road race MK3, I'd start with a cheap hardtop chassis instead of a targa and I'd start with the hole saw diet, a decent roll bar, good seats, steering wheel, etc, and focus on getting new urethane or stiffer bushings in everything under the car along with some coilovers and big brakes, along with a running stock of suitably set up 17x9 or 18x9.5-ish sized wheels and tires to sort out, and get the suspension and car dialed in to be happy with a 'square' or un-staggered wheel and tire setup so you can get the most out of sticky tires.

Even if you left the engine stock, that's a lot of work to tackle for a 'why not' road race build that will not be competitive in any way it's classed with the SCCA, NASA, etc at local road race events.

Then there's the whole swap process and getting that dialed in and tuned and making decent power, etc...

Honestly, to get that figured out will take hundreds of hours of work and cost you a lot more than simply buying a C5 Z06, putting a fixed racing seat, sticky tires and brake pads, and a tune in it and going road racing.

If the Mopar bug is what's itching, one can find a 2009-2014ish 5.7L 6MT Challenger with a salvage title and higher miles for the mid-low teens these days, and a full 'because race car' weight reduction program along with a set of take-off SRT8 brakes with sticky pads and some suspension upgrades can do the trick as well. I suspect that as boaty as the C3 Challengers are, if you diligently ditched all the interior comforts and sound deadening, etc, you could get within a couple hundred pounds of a gutted MK3 by the time it was all done all while having an already-running car with decent parts support and a lot less headaches to sort out. A decent cam and some long tubes will wake up an 09+ 5.7L to the mid-low 400whp range through the TR6060 6-spd, and sound great doing it. You could do an AAR style road race build, too.

Just some food for thought, having been playing these games myself for 2+ decades and having seen a hell of a lot more projects like this get started than get finished.
 

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but it sounds good on paper, mopar+r154 bolt up

op you may know more than me about machining / engines etc on and on

but have you driven a r154 car and shifted above 6k rpm. its literally a truck trans that was stronger than the (better shifting) w58 so they used it in the turbo car. bellhousings are available to swap into mk4 jz cars, and new units are even available. but for some reason people elect to spend 2-3x more to do the grannas 6 speed. personally Ive spent years debating in my head how to move on past my cars w58 and the r tranny really has no appeal. you really want all that modern v8 power and not have the ability to put it down with some slicks once and a while ?
 

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That's a nice looking 87 - it picked up 89+ mirrors and trim at some point too, but kept the 87-88 front bumper. Perfect!

Even if you left the engine stock, that's a lot of work to tackle for a 'why not' road race build that will not be competitive in any way it's classed with the SCCA, NASA, etc at local road race events.

Honestly, to get that figured out will take hundreds of hours of work and cost you a lot more than simply buying a C5 Z06, putting a fixed racing seat, sticky tires and brake pads, and a tune in it and going road racing.

Just some food for thought, having been playing these games myself for 2+ decades and having seen a hell of a lot more projects like this get started than get finished.
Sharp looking car indeed. Jesse, I wanted to touch on a couple points that Jeff (Weckless) mentioned. I built my 87 Supra to be a road racing car, and it has taken a while, but... it's pretty well sorted for something built by a dork in his garage, and it's a hoot to drive. Along the way, I discovered autocross. Locally, our classing is pretty flexible. Not sure how your region of Canadia will affect you in this regard, but SCCA in particular is not very kind to anything more than mildly modified when it comes to Supras. Mine is classed in either SM or SSM, which I joke is short for "Serious Machinery" and "Super Serious Machinery" because of the kinds of cars that show up.

Not saying a Mk3 can't be competitive, because, frankly... I think it can. That said, it is still absolutely a long and difficult road you're going down here. I'd go so far as to say that for what I intended to do with my car, a C6 Z06 would have made WAY more sense, and saved me at least, if not more than half of what I've put into my car.

Cool idea for sure, but like Jeff says, a lot more of these projects get started than finished. We'll root for ya though!
 

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Discussion Starter #15
this is a cool project imho. is the hemi a smaller narrow v8? Not really but with the sparkplug access of the G3 and headers facing straight down that is a big +

but the trans and rear end (for that matter) are wrong for all that low end torque / rotating assembly weight and shock

r154 holds 600 hp of jz because its coming on high in the rpm. lower torque but at a higher rpm Naww my G3 only makes 480 tq and I'm not going to drive like a 16yr old

that monster hemi has to be the opposite. loads of torque at way lower rpm.

not a mopar guy ...but isn't there a better trans that bolts to that engine from the factory ? Nope
 

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That's a nice looking 87 - it picked up 89+ mirrors and trim at some point too, but kept the 87-88 front bumper. Perfect!

Having worked on a decent number of modern Mopars when I still worked in the performance industry, there's a few things that immediately come to mind.
First, oil pan and oil filter housing clearance in the MK3 subframe. We did a 6.1L crate Hemi swap into a 71 Challenger and clearance of all that stuff was a nightmare. There are very few alternate designs from other applications to swap to and a dry sump is a shitload of money. I'd mock that part up and figure out mounts, bell housing clearance and firewall clearance etc to get the engine as far back as possible for better weight distro, considering your intended goal. I am worried about firewall clearance.
Also consider header clearance with the steering shaft, etc. The further back you get the motor in the engine bay, the less that sucks, but the more you'll likely have to fuck with the oil pan, etc. Totally agree..thanks

Second, get a TR6060 from a wrecked Challenger and live happily ever after. There is absolutely no sense fucking around with an R154 and a custom pilot bearing chingus and all that bullshit for the shifter, ratios, etc that you get with an R154. Sell the R154 for $800-1000 to offset the cost of the TR6060 and live happily ever after. Yes, shifter location will take some fuckery and yes you'll need a custom driveshaft and all that but the common rear end ratios available for a MK3 will be an excellent range from which to pick, and you'll want a lightweight 1-pc driveshaft anyway given your purposes. Not f'ing with this at all--way simpler to keep the R154

Wiring wise, follow the TSRM's but given the way Mopar PCM's are set up these days you'll basically be running all Mopar wiring and ECU and simply integrating it into your main ignition power, etc. You will probably want to get the OE fuel pump from an SRT8 or Hellcat and use the Mopar's PCM to run that with PWM since all that shit is set up as a returnless fuel system and that's a clusterfuck to get around and keep the Mopar PCM happy especially if it's newer than 2015 or so. You'll likely have to get creative with FP control wiring and the fuel line as well. I would recommend finding a small charcoal canister, relocating it to under the rear of the car somewhere, and venting it to atmosphere to relieve excess tank pressure, and capping off the return line entirely. This is where I will likely lose some of you guys--I will go carb but will go Holley Terminator X or Megasquirt in the future. The wiring is the worst of my worries and yet the least.

Gauges will be interesting - you could use the 7M's coolant temp sender and oil pressure sender to keep those gauges, the gas gauge would be fine too, but Tach and VSS will be a bitch because the tach is straight coil pack driven and the VSS is cable-driven in the MK3, and the Mopar PCM runs both tach and VSS gauge output as CAN bus shit if memory serves. You might be able to rig a tach signal from one of the coil packs, and get a VSS input for an aftermarket gauge from an ABS hall sensor with a Dakota digital VSS box to adjust it to match speed, but that doesn't fix the speedo itself in the MK3 cluster being cable driven. I hope I can drive the tach with the MSD HEMI someway somehow and drive the Speedo---all other gauges IDGAF.

Personally, having laid hands on Coyote 5.0L's, Chevy LS's, and Mopar Hemis of all modern flavors - I think the Hemi swap will be significantly more difficult, expensive, and complicated than an LS without any tangibly superior results for your goals. You will have far wider parts support, different OE options for custom configurations in accessory config, belt drive, intake manifolds, oil pans, headers, cams, etc with an LS and you'll have equivalent if not superior configuration that's easier to tune and has a vastly more flexible factory PCM that can easily be re-tuned to accommodate swap fuckery than the Mopar PCM. You're talking sense here but never will I ever go another route.

Beyond all that, building a road race MK3, I'd start with a cheap hardtop chassis instead of a targa and I'd start with the hole saw diet, a decent roll bar, good seats, steering wheel, etc, and focus on getting new urethane or stiffer bushings in everything under the car along with some coilovers and big brakes, along with a running stock of suitably set up 17x9 or 18x9.5-ish sized wheels and tires to sort out, and get the suspension and car dialed in to be happy with a 'square' or un-staggered wheel and tire setup so you can get the most out of sticky tires. Is what I have a targa? Agree with everything else you have said.

Even if you left the engine stock, that's a lot of work to tackle for a 'why not' road race build that will not be competitive in any way it's classed with the SCCA, NASA, etc at local road race events. I'm just that kinda guy--I want to try and chase down high end stuff on the road course with far less.

Then there's the whole swap process and getting that dialed in and tuned and making decent power, etc... I am not new to this stuff(just Supra quirks) not tuning/ not troubleshooting/not making power etc...

Honestly, to get that figured out will take hundreds of hours of work and cost you a lot more than simply buying a C5 Z06, putting a fixed racing seat, sticky tires and brake pads, and a tune in it and going road racing. Naww it won't and I ain't buying a C5 Z0-anything and won't ever. It will be an Audi or a Porsche if I catch a bug that bad and that won't ever happen either.

If the Mopar bug is what's itching, one can find a 2009-2014ish 5.7L 6MT Challenger with a salvage title and higher miles for the mid-low teens these days, and a full 'because race car' weight reduction program along with a set of take-off SRT8 brakes with sticky pads and some suspension upgrades can do the trick as well. I suspect that as boaty as the C3 Challengers are, if you diligently ditched all the interior comforts and sound deadening, etc, you could get within a couple hundred pounds of a gutted MK3 by the time it was all done all while having an already-running car with decent parts support and a lot less headaches to sort out. A decent cam and some long tubes will wake up an 09+ 5.7L to the mid-low 400whp range through the TR6060 6-spd, and sound great doing it. You could do an AAR style road race build, too. I agree, but NEVER those f'kn things are tanks and I would rather do a mid 80's RAM shorty--which I am-lol

Just some food for thought, having been playing these games myself for 2+ decades and having seen a hell of a lot more projects like this get started than get finished. The G3MK3 will be on the road this summer (2020)
J.Rob
 

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yes- the car pictured on the first post is a targa. the roof panel is removable. flip the sun visors up and you will see 2 of the screw attach points.

the targa cars are known to have more chassis flex, and they (supposedly) weigh more because there is bracing added in the unibody
 

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Discussion Starter #18
but it sounds good on paper, mopar+r154 bolt up

op you may know more than me about machining / engines etc on and on

but have you driven a r154 car and shifted above 6k rpm. its literally a truck trans that was stronger than the (better shifting) w58 so they used it in the turbo car. bellhousings are available to swap into mk4 jz cars, and new units are even available. but for some reason people elect to spend 2-3x more to do the grannas 6 speed. personally Ive spent years debating in my head how to move on past my cars w58 and the r tranny really has no appeal. you really want all that modern v8 power and not have the ability to put it down with some slicks once and a while ?
I have not driven a r154 car. I have done my research and owned a few Toyotas and thus respect them. I also know quite a bit about manual trannys--I have driven and pounded a bunch. T-10's to 833's to T5's to Richmond's to Hyundai Excel 5spds and everything in between--broken a few, burnt a few (popping out of gear) none have impressed me that much except for the Hyundai Excel and anything Toyota had. Therefore I am confident the r154 will measure up. That being said the info on these is scant. What kind of RPM will they actually shift well at 5500rpm? 6000rpm? etc... I cant see Toyota putting these behind a tractor type engine (low RPM). BTW the car in the pic has no engine and the tranny feels notchy and mechancal and beefy which is exactly what I'm after. Thanks for the response, J.Rob
 

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Sharp looking car indeed. Jesse, I wanted to touch on a couple points that Jeff (Weckless) mentioned. I built my 87 Supra to be a road racing car, and it has taken a while, but... it's pretty well sorted for something built by a dork in his garage, and it's a hoot to drive. Along the way, I discovered autocross. Locally, our classing is pretty flexible. Not sure how your region of Canadia will affect you in this regard, but SCCA in particular is not very kind to anything more than mildly modified when it comes to Supras. Mine is classed in either SM or SSM, which I joke is short for "Serious Machinery" and "Super Serious Machinery" because of the kinds of cars that show up.

Not saying a Mk3 can't be competitive, because, frankly... I think it can. That said, it is still absolutely a long and difficult road you're going down here. I'd go so far as to say that for what I intended to do with my car, a C6 Z06 would have made WAY more sense, and saved me at least, if not more than half of what I've put into my car.

Cool idea for sure, but like Jeff says, a lot more of these projects get started than finished. We'll root for ya though!
Thanks for rooting for me, I appreciate it. This is a labour of love not a desire to be the cheapest and fastest (Z06). I'm a logical guy but love to do things my own way as most guys do. I'm not usually an EASY button kind of guy. Don't care about classes , just wanna have some fun taking neighbours for rides and have some fun at open track days and tread off the beaten path. F-the EASY button. J.Rob
 
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