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Kouki 86 low mileage direction - Supercharger/Lightweight/GR

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My ideal 86 would sport a light revvy flat 6 but that is next to impossible/insanely expensive and complicated.

I'd been thinking down the lightening/attempting revvier FA20 by flywheel/propshaft/intake/electric water pump (cribbed off Adrian @Fensport's car) but I get the impression that one would still be fighting an uphill battle. In my experience the GT86 is actually a heavy car. Not helped by a heavy engine with heavy parts. In short I guess I'm wanting to turn the FA20/GT86 into something it's not. Perhaps a reasonably priced Exige V6 is a route to that end at some point in the distant future.

Anyway I spoke to Scoobyclinic the other day about a completely unrelated car and mentioned as much about the above and the chap there was extolling the virtues of twin screw superchargers. Low down torque is indeed something I'm after (as well as/aside from the smoothness/power delivery of a 6 cylinder) and after getting my 86 back on the road after 4 months away from it I think the bloke at Scoobyclinic might've seeded something.

My biggest misgiving about the FA20 is the fact it doesn't rev up sharply. Once you've driven a TVR straight six not much will compare but that's a whole other kettle of bananas. I'm now wondering, instead, how about a supercharger vs attempting lightness vs selling in the next 6 months and putting my name on the list for a GR86?

There are a few things I could still do with a supercharger to minimise weight which apparently would add around 27kg for the Sprintex. I'd guesstimated a 70kg weight reduction would be noticeable on the the stock GT86. Already lost a kg or two with the Tomei UEL I have on there with Fensport tune (top work there, elated with what they did with the engine, props again to Andy at Fensport for fitting) but it's a very difficult endeavor to try and get the other ≈68 kg off. Wheels/carbon fenders/batteries etc would be in that plan but also could apply to a supercharged car. In terms of throttle response forced induction may somewhat compromise immediacy but would net me the low down torque I'm after. I was loathe to add anything else to the crank auxiliaries as I'd laid blame at the flat engine's dual DOHC heads/AVCS but, pft, can't have it both ways and I'm still intrigued by the neatness Adrian's electric water pump setup enabled subtracting a pulley and tensioner or two

So, completely foregoing all that expense and complication there's the third option: GR86 ! I'd likely sell in the next 6 months whilst used prices are high and my GT86 has only done 19.5k. The other big plus of the GR86 for me is the upgraded transmission and drivetrain parts. I've already twice attempted to address 3rd-2nd shifts with gearmount inserts and latterly the TRD mount and there's also still TRD/STi engine mounts + diff mounts to try but the GR86 would have drivetrain improvements there + torquier engine already in situ from the factory. It's a whole thread in itself spending ££ on a low mileage 2017 86 vs a GR86 but it's only mechanical upgrades that concern me in that equation. Realistically, given funds I'd only be able to do one or the other and I'm not inclined to go halfway on this car only to be unsatisfied and have to start again with the GR86. I must've already spent over £3k on mods (have done catless manifold and tune twice).

Interested to hear opinions from people with experience. Obviously very few in the country have tried a GR86 so that's a kind of can I wait til mid/late 2022 to demo situation and in all honesty I'd be sensible to concentrate on more driving lessons in the interim to better make use of what is a very capable car that far outstrips my skill. Still covet that lightness though, just don't think it's realistic. Nice one, cheers :)

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Lightness is certainly possible if you're prepared to make the usability sacrifices - Revolution in Japan and a chap in the US managed to get there's down to under a tonne.

You could also swap the Tomei manifold for a longtube manifold to benefit from the extra power and torque you'd gain there for minimal weight change.

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Right now the used car market is on fire. Also Toyota confirmed the GR86 wont meet future emissions so it’ll only be on sale for two years.

So I believe the smart money will be on selling your car now for top dollar, getting a GR86 on preorder and just doing without a sports car for a while until the new car arrives. Or if its your only car you could buy a few hundred quids worth of beater off ebay to use for 6 months (then just PX it in against the GR86 when it arrives).

Supercharging/turbocharging your 86 is something many of us have done (myself included) with great results, but if you can sell your GT86 and get a GR86 with the combined money you would have otherwise spent charging your current car then makes sense to get the limited edition new car which has the power you are looking for straight out of the box.

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On 12/18/2021 at 10:36 PM, Deacon said:

Lightness is certainly possible if you're prepared to make the usability sacrifices - Revolution in Japan and a chap in the US managed to get there's down to under a tonne.

You could also swap the Tomei manifold for a longtube manifold to benefit from the extra power and torque you'd gain there for minimal weight change.

I've seen those two lightweight ones, Dori Dori certainly got excited by the Revolution one. Sadly had gearbox problems in one of the vids I saw.

I'm happy with the Tomei manifold for now as it's more punchy with the Fensport tune than the TD EL I had on there before. You're right though it would require drastic work to get it lighter. I only weigh 55-60 kg and could definitely feel a 90kg passenger so to approach taking that off the front would be nice but there's not a great deal to work with is there? :( 

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On 12/19/2021 at 10:34 AM, Leeky said:

Right now the used car market is on fire. Also Toyota confirmed the GR86 wont meet future emissions so it’ll only be on sale for two years.

So I believe the smart money will be on selling your car now for top dollar, getting a GR86 on preorder and just doing without a sports car for a while until the new car arrives. Or if its your only car you could buy a few hundred quids worth of beater off ebay to use for 6 months (then just PX it in against the GR86 when it arrives).

Supercharging/turbocharging your 86 is something many of us have done (myself included) with great results, but if you can sell your GT86 and get a GR86 with the combined money you would have otherwise spent charging your current car then makes sense to get the limited edition new car which has the power you are looking for straight out of the box.

Have to agree with everything you wrote but there's still part of me that wants to continue with the GT86. I've calmed on the supercharger a bit as it dawned on me that not only would the extra weight be over the front (which I was thinking I might abide by) but it'd also be right at the top affecting COG. I'm a believer in the flat engine adding to the handling on the GT86 so I couldn't resolve compromising that. 27kg might not be a lot in the grand scheme of things but to have it atop the engine, well, I can see Tada San's argument about not having a turbo due to the intercooler etc. I can imagine they'd have got rinsed for extolling the virtues of the flat-4 low COG but then whacking a bunch more stuff on top.

My current quandry is about using my current car as a kind of test mule for invasive mods that I wouldn't want to try on the GR86 only to not get on with them and have to revert to stock. Top of that list is a lightweight flywheel which I'm just itching to try. Engine mounts too. I suppose I shouldn't do anything until I test drive a GR but it could be ages until they get here! Definitely want to have some driving fun come spring & summer.

One thing that Tom at Fensport pointed out to me is that with the 2017+ FA20 D-4S you have a fairly mature design whereas there may be some things that need ironing out with the FA24 D-4S after its been out in the wild for a bit. Perhaps the GR86's FA24 will benefit from the 3 years the Ascent's FA24 DIT has been out for but there's gonna be a load of variables still.

Tricky decision and my head is saying GR86 but it does feel like a bit of a shame to not scratch some itches with the GT86 rather than letting loose and partially voiding warranty on a brand new car with drivetrain mods and mapping etc

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I think I'll say a few things here:
1. You can go down the weight saving route but it's a lot of money for not much gains - CF Bonnet, Forged alloys, S Steel catback are three quick ones I can think off. Lightened flywheel will have its pros and cons as generally it makes city stop start driving harder.
2. My personal learning is that mods help you personalise your car but financially, you will recover very little of it when it's time to resell.
3. If you don't put the car back to stock, you will find very limited buyers. Hence you might have to compromise on a poor PX value.
4. A PD SC does make the car feel like it has a bigger engine. A Harrop has a TVS1320 SC, so effectively adds that much more air. So if you take away 320cc losses. It adds a litre more capacity to an engine. So its closer to your 3L flat 6. The new GR NA will not match that power number even with NA mods of a manifold and tune.
5. The GR86 might have new issues to iron out is a bit of scare mongering as the gen 1 from 2012 ( new launch) never had major issues. Only the valve spring, which went across models as it was a bad batch from supplier. I wouldn't worry about platform issues and happily put my money on a new GR86 and be done with it if all you want is more oomph.

Sent from my SM-G781B using Tapatalk

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On 12/18/2021 at 9:07 PM, Feemono said:

I'd been thinking down the lightening/attempting revvier FA20 by flywheel/propshaft/intake/electric water pump (cribbed off Adrian @Fensport's car) but I get the impression that one would still be fighting an uphill battle. In my experience the GT86 is actually a heavy car. Not helped by a heavy engine with heavy parts. In short I guess I'm wanting to turn the FA20/GT86 into something it's not. Perhaps a reasonably priced Exige V6 is a route to that end at some point in the distant future.

 

That's seems a little harsh, at 1.25 tonnes the GT86 is actually quite light in the grand scheme of things. You're right about the uphill battle though in a roundabout kinda way, a large number of the panels are aluminiium so you won't see huge weight losses from doing the odd panel in GRP/carbon fibre. You'd really need to do a lot and that gets expensive really rapidy.

You're best bet for cutting weight is wheels/exhaust/battery and go from there. Even most of the interior isn't that bad, the big saver there is the seats. There's a thread over on FT86 club which is worth a look as somones been through quite an indepth weight saving process completre with component weights.

https://www.ft86club.com/forums/showthread.php?t=7881

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From what I've read, I think your going to have the same issues with the new GR86 that you've got with the current GT. The Subaru boxer engine isn't really a revvy engine and it's not been designed that way. Yes the new FA24 has more power and torque which is why its faster, but it still won't be a light engine that likes to rev freely. You can ofcourse try and make either engine much lighter but we'd be talking (tens?) thousands of pounds with an engine rebuild featuring a stroker kit, lighter rods, pistons and upgraded cams. 

What's your ultimate goal for the car? Just to be a fast daily or a track car. 

If your happy with the current car, I'd atleast go down the lightweight flywheel and driveshaft route to begin with.

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Even with redline as is FA engines imho are "revvy" enough, way more so then average family car engines with redline ~ 6K. And those very few engines that did rev higher, eg. in S2K AP1 were replaced with torqier but with slightly lower redline in AP2. So imho revvy & sporty by my taste enough.

As for lightening car .. i'd think of complex solution. Both slight power increase (via eg. ecu tune & catless header. or going supercharging route), and lightening (removal of crap in boot, deletion of rear seats, replacing heavy stock seats with light bucket seats, replacing heavy battery with l/w Li one, installing smaller washer fluid tank, installing lighter wheels & BBK. Doing these imho should retain most of comfort features.

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Having had both Sprintex and Harrop chargers, go for the Harrop which is a better solution, has less heat problems, and can give you excellent torque low down, transforming the engine.  How about boring out the FA20 to 2.2l, using forged parts and then supercharging it?  That would be a pretty mighty solution.

If I could afford the off-road time, I would do exactly that to my engine.

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Thanks for all the responses. I've held off replying as I've been going round and round in circles (sometimes in the car;) as to what to do.

Small update and one thats made me feel rather annoyed. Whilst looking into the differences between UK OEM air intakes and the JDM/Aus/North American 2017 update I've realised from looking at pictures online that I'm missing a branch resonator from the intake boot in between the airbox and the throttle body. It's been blanked off with a plastic cap and a jubilee clip/hose clamp.

I've never been satisfied with the throttle response on my car since the first months of ownership in Autumn 2019 but I accepted that was the stock performance so set about doing the manifold/tune to try and improve it. Few thousand pounds later it's still there but only today have I put my hand under there and felt what's missing. I've had the car in storage a few times as its not been my daily driver and I haven't put a great many miles on it.

All this time and dissatisfaction with the throttle response. Doh. Miffed kind of describes it. Have spoken to the Toyota dealership that supplied me with the car and waiting to hear back from them.

Cheers again for the replies, will be interesting to see the outcome.

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No there should a dingleberry on the 90 degree bend towards the throttle body. The intake hose that many replace when doing the sound generator delete. 

I got the inkling that there was an issue from some of @Kodename47 posts here and there where he was experimenting with removing said branch resonators only for the engine to bog. It happens on my car at low engine speed gear changes, the engine momentarily chokes just once as if it was just about about to stall. It's made the car crap to drive but I initially just took it to be the factory tune/stock catted manifold. Then I got the car tuned + aftermarket manifold and it happened worse n I told the tuner who disbelieved that it could happen. I washed my hands of that tuner because of that. Not their fault I see now but the way they responded made me not want to deal with them anymore. I then took it to another tuner a year later for another manifold + tune and it was better I think through brute force in a way whilst we had hot weather in the summer. When I was at Drive Limits the instructor (I forget his name) mentioned I should get the intake checked for leaks as the revs fell unnaturally slowly on an emergency brake stop. I've not been driving the car much due to living away but it's my only car now so after replacing the battery and driving down south in the cold I had the issue again and it's put it back in mind.

All a bit of a learning curve I suppose but one that has verily sullied my enjoyment of the car. 

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I needed to open a picture of the engine bay to see what you mean

 

https://www.ebay.co.uk/itm/2012-ONWARDS-TOYOTA-GT86-GT-86-2-0-ENGINE-SUPPLY-FIT-INCLUDES-COLLECTION-/333768813201?var=0&mkevt=1&mkcid=1&mkrid=710-53481-19255-0&campid=5338268676&toolid=10044&customid=Cj0KCQiAraSPBhDuARIsAM3Js4qsDdXzVVjYfdQsWoEhpiaBnsyJ_T07xzVVx-q3W7S580aK0Csv3-waAmJ1EALw_wcB

I don't know its specific purpose but clearly it being missing / disconnected is not right and might be the cause of your problems. So try getting it reinstated and let us know what happens. Might be worth calling one of the GT86 specialists like TD , Abbey, fensport. They might be quickly able to help.

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I've no idea what it does, possibly just for noise levels. Though it could do some Voodoo to the incoming air, add turbulence/help build a certain amount of pressure or something.

I'd want it adding back if the car doesn't seem to be running properly.

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Is just the type of weird debacle that befalls me this missing resonator. But on the plus side I'm looking forward to definitely having an improvement in throttle response when I put it back in the system! Fuji/Toyota would not have added the cost of that piece if it didn't improve things.

 

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9 hours ago, Feemono said:

Is just the type of weird debacle that befalls me this missing resonator. But on the plus side I'm looking forward to definitely having an improvement in throttle response when I put it back in the system! Fuji/Toyota would not have added the cost of that piece if it didn't improve things.

 

I don't think it's going to be the cure you're looking for. I noticed no difference with it on / off mine. Sorry!

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4 hours ago, Deacon said:

I don't think it's going to be the cure you're looking for. I noticed no difference with it on / off mine. Sorry!

Eeee, straight from the horse's mouth! Not that I'm calling you a horse (;

Well the suspense is killing me still. The way I drive day to day I seem to bump up against this issue of choking/momentary hesitance when reapplying throttle at low engine speeds so I was hoping it would at least be partly ameliorated with the resonator. I'm still gonna harangue the Toyota dealership for it.

Thanks for managing my expectations though Deacon :)

As luck would have it someone's breaking a GT86 in my hometown and they've listed the exact part I need... for £49 😐

Interestingly as well, out of the Perrin and Mishimoto intakes that reside in front of the engine bay in the bumper Mishimoto's retains this dingleberry as they say in testing it did contribute towards performance whereas the Perrin dispenses with it.

I feel a bit like Lloyd in Dumb and Dumber, "This branch resonator will improve your performance by 1/1,000,000th" Me: "So you're saying I can improve the performance on my car?!"

All this came about quite by accident as I've been looking into replacing the UK airbox with the JDM/Aus/N. American 2017 one. 0.577 m2 increased filtration area, it'll be like adding bloody nitrous oxide to the car 🤣

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I think it's a Helmhoz resonator. IIRC they are used to control pulse waves in the intake. I don't think it would improve throttle response.

I recall reading about some throttle hesitation in the FRS forum that was traced to the PCV system not scavenging properly. This was on a turbo-charged car so it's probably not related but it's another possible avenue.

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3 hours ago, GravelRash said:

I recall reading about some throttle hesitation in the FRS forum that was traced to the PCV system not scavenging properly. This was on a turbo-charged car so it's probably not related but it's another possible avenue.

Ah thanks. I'll have a check there to make sure everything is in order.

I was reading the other day about crankcase ventilation vis-a-vis oil catcher cans but like you say they seem to be more imperative in practice on turbo'd engines.

Thanks again for all the replies, there's so much to learn about on these modern engines. Not that I knew much about simpler engines in the first place but there's so many auxiliary components on the FA20/GT86 that whatever you think you know you end up probably not knowing lol. Now where did I put that SOHC EJ22 I was gonna swap in...

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9 hours ago, Feemono said:

I seem to bump up against this issue of choking/momentary hesitance when reapplying throttle at low engine speeds

Yes, I get that on my supercharged BRZ.  It doesn't bother me much as my commute is mostly medium-high speed but the pickup after slowing down for a roundabout, dropping to 2nd and then giving it some throttle is a momentary hesitation.

Interestingly, throttle response at any other revs is lightning fast.

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27 minutes ago, MartinT said:

Yes, I get that on my supercharged BRZ.  It doesn't bother me much as my commute is mostly medium-high speed but the pickup after slowing down for a roundabout, dropping to 2nd and then giving it some throttle is a momentary hesitation.

Interestingly, throttle response at any other revs is lightning fast.

Interesting. In between that, the snicky triple synchros, the transmission fluid warm up, the slightly indefinite clutch spring assist, the variable throttle mapping and the lack of low down torque the GT86 doesn't always make for the most fluid driving experience ey! I need to focus on my clutch action as I had an operation on my left knee which has left me with tight tendons etc and as a result I tend to just lift my whole leg off the pedal rather than pivoting at the ankle. I think it messes up the exact point at which I declutch so whilst I think I've rev matched pretty well there ends up being a discrepancy.

Again, very grateful for the responses which are helping to illuminate all these little gremlins out to sabotage my driving. We all have our reference points and mine is an old 16V 1.6 SOHC FWD Mazda 323f. That thing revved like billy-o and I could change gears almost instantaneously. Years later moving over to a RWD car with x kgs of two piece propshaft spinning is quite a different proposition. Up to that point all the RWD cars I'd driven were automatics with a Volvo 340 being the manual transaxle outlier. Always felt like I was driving a tractor with that thing.

Someone remind me again how much Fensport charge for installing that Samsonas sequential box? 😆

 

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9 hours ago, MartinT said:

Yes, I get that on my supercharged BRZ.  It doesn't bother me much as my commute is mostly medium-high speed but the pickup after slowing down for a roundabout, dropping to 2nd and then giving it some throttle is a momentary hesitation.

Interestingly, throttle response at any other revs is lightning fast.

I think this is exacerbated by the charger bypass valve on a charged setup but I do notice the same!

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Have you tried an ecu reset?

https://www.ft86club.com/forums/showthread.php?t=68328

You could also try to recalibrate the throttle pedal.

I’ve got the TD NA kit, and if the issue is similar to what I get at around 3000rpm, a slight hesitancy then surge on reapplying the throttle, I wonder if it could it be something to do with the VVT

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