Roman's 4GR V6 Toyota Carina

[Roman]

I am so absolutely stoked to have some garage space again. Feels like I've been let out of jail or something! 
So I have been burning the midnight oil a bit. 

I got the passenger side manifold all finished, filled it all up with water and no leaks. 
So hopefully it's good haha.

I started on the rest of the exhaust a while back, but will chop it back up and redo it. As I was kinda thinking I'd make the extractors to suit the pipe locations, but it's worked out the other way around.
I am so absolutely over the moon to be able to spend nights or rainy days working on things now. 
The collector doesnt look so tiny/weird now that the rest of the pipe is on it. 

Just need to add the rear part after the collector onto the other side too, then I can make a start on the 2-1 section and rest of exhaust.

[Roman]

The cable that links the banks of throttles together was made from a motorcycle cable repair kit, so one end had a little screw in type fitting. 
However problem is that you need to push the cable all of the way through and out the other side to tighten it properly. Which I cant do, because of how it slots in. 
So I just left some cable hanging out the other side, then buzzed it with the tig and now it's sweet. 
I could lift up my bench vice using that connection so think it will be fine for pulling some throttles open. 

Burning the midnight oil some more, now that I can. I drained the brake fluid and got the Soarer booster and master cyl out.
I was hoping to fit this KE70 booster, which is much smaller diameter so gives me a bit more room to get bolts in. 

But unfortunately the bolt pattern through the firewall is different. 
The Soarer is 100x70mm, the KE70 is 80xsomething I think. 
It's tempting to redrill the firewall holes but the bracket on the other side has spacers/dowel type things on it, which make it more effort to redo properly. 
So will keep on the lookout for a slightly smaller booster with a 100x70 pattern.




It's looking as though a Hilux Surf has the same pattern, and hopefully a smaller booster. So will try find one of these, unless anyone has something similar lying around they could measure? 
There's one on Trademe so I've asked the guy if he can measure it up. Otherwise looks like there are some Surfs at pickapart, so will have a look next time I'm in Auckland.





 

[Roman]

Toyota legend Mark Roads has a Spare Celica/Carina GT-T spec brake booster.
Which is a little smaller than the Soarer one, and will bolt up.
So will go pick that up some time next week. 

Back to the firewall problem, I borrowed a laser projector tool from @flyingbrick that is a cool piece of gear. 
It can draw a 360 degree line, all on the same plane. 
So I'm going to mark where this line lands everywhere, Then I can either cut the metal back to this line so it's all straight. 
Or, is use it as a reference point for knowing how far a piece needs to bend back or whatever.
Makes the problem seem easier in my brain, having some sort of reference point to work to.
I'll need to pull the motor back out to do this properly, so will dig out all of my engine crane parts out of storage and make a start on that.
Slowly making progress on a few different fronts which is good.

[Roman]

Pulled the motor back out to do firewall activities. 
Borrowed more of Nathan's stuff, so I could hang it all off the scales and see how we're looking weight wise now that most of the stuff is finalized.
This is with motor, flywheel, clutch, engine mounts, clutch slave&master, gearbox, alternator, exhaust manifolds. 
And a pair of extra exhaust flanges which I'm hanging the motor from. 
So 209kg all up isnt too bad. For reference @Hyperblade had the full beams 3SGE setup sitting at around 199kg when using ITB kit and 1NZ alternator.
Or for some other context, people list the weight of a 1JZGE alone at around 200-210kg.

So by switching from lead acid battery to a lithium one I've as good as neutralized the weight gain.
Then there are some other currently podgy parts like the factory seats still in there. 
So, this should still be a sub 1000kg car with most of the interior in, I'd imagine.

[Roman]

Well I'm making progress towards getting things going. 
Firewall isnt finished, or pretty, but if it stops my face catching fire for now, that's a win. 
Has got a severe case of myspace photo angles here, looks fairly rubbish in person.
Posting here before it ends up on @cletus's wall of shame instagram story for being crappy things brought in for cert.




Also welded up the engine mounts properly, and reshaped the front of the mounts so they look a bit nicer. Then a few coats of only the finest rattle can black.
I'm out of town for work for most of next week, but I'm hoping to get the engine back in and fired up by next weekend.

[Roman]

Sorry to everyone that I have blue balled with this project!
Over the period of god knows how long it's been so far without any cool stuff happening.
I have not yet made good on my promise of doing zillions of rpm with a shitbox wrecker engine. In V6 variant at least.

I've been putting in some solid hours to get things finished to try get to the drags.
But tonight I've come to see I'm not going to make it. 
If it was just about getting the car finished enough, might be feasible with some long nights.
However it turns out I need an MSNZ license as well as a log book in order to race without wof/reg.
I've been going down this road over last few days to try organize it.
I paid $70 to join a car club, which is a prerequisite to applying for a license.
However it was then was going to be another ~140ish bucks for a license that might not arrive in time. 
So combined with some extra expenses to get car in a drivable state I'm probably looking at $7-800 I need to pull out of my ass in a hurry.
My bank balance got fairly well emptied a week or two ago when the neighbors dog tried to eat our cat. Then the cat crunched my finger when I picked it up. 
So big vet bill for the cats injuries, and a week on antibiotics and a day or 2 with bandages for me.
So as exhausting as it has been pushing hard to get this done. For now I just have a rest.

But it's really close to being drivable. 
Since last post:
-Firewall finished
-Put crossmember and steering rack back in
-fixed gearbox leak (loose bolt) 
-fixed engine oil leak 
-finished exhaust manifolds on both sides, down to a finished flange. So they can stay in for good while I make rest of the exhaust.
-Got motor and box back in
-TA63 booster fitted
-Interior started going back in 
-Started on battery tray
-ITBs properly fitted and bolted/sealed up
-Exhaust manifolds on properly with gaskets etc, all bolted up properly 
-Some wiring stuff sorted
-2nd wideband wired up 
-radiator back in
-front of car back together 
-Motor fired up again! 

My collector flares out to 2.25" or 2.5" (cant remember) but then you can see down where the flange ends up, thats where it flares out to 3".
So does this mean it's an F1 car now? haha.
The last weld I did on this pipe was the one on the rear of the 3d printed part, and turned out quite nice compared to some earlier efforts.
Also, although I'm no welding expert by any means.
Holy shit, it feels like cheat mode being able to weld indoors.
So much easier when you're not battling a mild breeze on the driveway. haha.


 



 

 

[Roman]

Alright alright alright 

Just been cruising a bit since drags pressure was off, but making progress every day. 

Radiator fan wired up and ECU triggering it.
2-1 section made. 
Both widebands connected and working. 
Engine holds water & oil fine. 
What I've so far made of the exhaust, doesnt leak. Excellent!
Has coloured up a bit. I'm stoked that this has worked out well. 




Mandatory engine noises:

Then I bled the clutch, and was making sure gearbox was good and everything working as expected.
It selects all of the gears fine, no weird noises or whatever. 
Clutch works fine and isnt overextending. 
So I was giving it some big revs while in 6th so there's a little bit of load on it. 
Then I noticed zero oil pressure. FFS.
Maybe spat a rocker or blew up a pulley again?
So I pulled engine covers off. Everything is in place, and everything has a healthy looking saturation of oil. Phew. 
So I'm suspecting that the pressure sensor shat itself, once it first saw some decently hot oil come past.
Will be pretty happy if it's just that. 
Thankfully I can get both covers off both banks, without having to remove any of the intake stuff or take all of the loom off. 
I do need to undo the clutch MC to get the cover off on this side, but I can easily reach the bolts since swapping to the slightly smaller TA63 booster.
Easy as.

[Roman]

I broke it again.... 

 

I was giving it some revs again and running through the gears. Got up to around 8600rpm. 
Loud ticking noise getting louder, pulled covers off to investigate. 
Found that one of the rockers had dislodged, but, not really dislodged. 
The bearing has come out of the center. then after that the rocker likely flew off, and then a valve got bent in the process somehow. 






So, not hugely bad in terms of engine damage...
The biggest expense is time spent replacing the valve.
I think the motor I pulled apart from last time at pickapart to get the intake valves out of.
Is still there waiting for me to go grab some exhaust valves haha. 
Although it'll be tricky to get this bent valve out, as it's bent from the top. Might need to cut it off somehow. 

With regards to a long term fix. 
Seems there are two possibilities and I'm not sure which yet. 
Either the pin vibrated itself into the 5th dimension, and just pushed itself all of the way through the rocker one side to the other. 
Or, the rocker flexed enough that the pin and bearing could come out the top.

So will investigate some options to beef them up, but might be time for a CNC project for some beefier rockers.

Someone mentioned to me that Papidakis racing was running a 9000rpm 2AR engine, and they have the exact same rocker setup in the head. 
I watched a teardown video, and turns out they ended up making some beefed up rockers to alleviate a few issues. 
So that might be best way to go. 



Also, although it's annoying to have another breakage, reminder to myself that this is what I signed up for. 
There are plenty of well trodden paths to go down, this is how it goes when there arent 5000 other people who've done the same yet. 
Engine knowledge is written in blood!

Will be interesting to see if there are any signs of deformation on any of the other rockers, they all looked alright by eyeball so far.

EDIT: 

Okay I know a bit better what happened now. 
So the pins arent even press fit, they are just staked in place. 
So I can actually slide the pin all of the way back in, very easily if you get it right way around.
there is juts a C shaped stake on each side, holding it in. So on this rocker the staking lifted, then the pin could easily slide out. 
So the pin definitely came all of the way out one side, not flexing the rocker and out the top.
So a tiny tig blob on each end might solve it, if I can weld accurately enough. haha

 

 

EDIT 2: 

I asked around on a Facebook group for 2GRs, if anyone had had similar issues. 
Someone mentioned that this is a common problem with the Boxer motors in the GT86, and so the they tig weld the ends, then it's never a problem again. 
So will proceed as planned!

 

[Roman]

Some surprises in the sump! 

Many, many surprises haha. 






This oil filter deserves a payrise, as everything post filter looks great. 
Will be interesting to see how much shit is jammed in there. 
I'm not even sure where this is all from yet. Simply remnants of the last few times this engine has shit itself? 
Relates to the rocker collapse? 
Run a bearing? 
Just left overs flushed through, from failed VVT pulley(s) ? 
Not sure yet.

 I wouldnt be surprised if a big end bearing (or all of them) got a real hammering when it bent all of the intake valves that other time.
But if this particular engine's swan song was to let me know that the rockers can blow to bits, and how to fix.
Then I salute it for giving one more snippet or R&D before it shat the bed.

Will yank the motor back out and then get a better idea soonish.

[Roman]

I got the head back off tonight. 
The combustion chamber etc, all looked perfectly fine. 
I tried hammering the valve out, and it just snapped at the bend - so the rest slid out the bottom. Easier than expected!
However the valve guide was already broken off at the top, and cracked further down.
So it would need repairs to keep using this head.

Taking the rest of the sump off, and there's definitely a whole bunch of shit in there.
I am still not sure where it's come from yet, as there's no damage to the rocker/cam/anything up top that can explain the volume of material that is present.





The worst damage that I've found apart from the valve/guide, was actually on the next cylinder over. From a previous incident.
Where some crap had fallen in, however that happened.
There were a few dents and a few pieces still lodged in. The piston looked mostly okay.
I thought I'd dodged a bullet on that one, but it probably would have caught up with me.
It would likely be a lot more prone to knock on that cyl. As some of the embedded bits might act as hot spots.
Which isnt a great thing given the high compression ratio already.

It's borderline tempting to just try clean this all up, replace a valve guide and reuse the head.
But this poor thing has taken enough of a hammering.
Lots of accumulative damage by now. Even if the big end bearings arent already toasted, they've probably had a hard time from when the valves all bent.
So this can go on the engine stand as an R&D/spares motor.

I had a look at all of the other rockers, to see if there were any other signs of the stakes failing.
There was 1 more which looked like it had had the pin had started shifting across.
But not quite enough to dislodge yet. 

Swapping in a new motor needs a fair bit of prep work. 

Things that need doing: 
-Plug up direct injection holes. (I might get them welded up this time)
-clean all of the carbon shit off all of the intake valves.
-install kelford valve springs and retainers.
-Tig all of the rockers. 
-Fit high tensile bolts and loctite to the intake and exhaust VVT pulleys.
-Fit cover plates to hold in the guts of the exhaust VVT pulleys. 
-Port the heads, at least to blend in the grotty intake bits.

Stretch goals:

-Maybe actually drive it this time 
-Get it all reliable enough that I can fit the big kelford cams. Thats when the party really starts. Hopefully.

[Roman]

I found the cause of the debris field. 
Two rods on the "bent valves" side of the engine, had essentially vaporized their big end bearings. 
So this motor is definitely off to spare parts heaven. Haha.



Some interesting evidence is showing in the bores on that half of the engine. Of the forces put on the pistons to bend the valves.
The piston coating has all been scraped off on the exhaust side only. 
Which I guess makes sense given that only one side of the piston (the other side) was conked really hard by the valves, pushing that side into the bore.



Ahh well, feels good to know for sure what happened now. 
I am looking forward to getting the new motor and making a start on it!

[Roman]

Regarding the rockers and welding them. 
Since they take a hammering I'm concious of doing stuff that will make the metal brittle or whatever. 
So what to do? 
Was initially thinking a few small tacks each side. 
But since the weld area is actually tiny, because these parts are tiny (thats an extension lead in the background) 
I figured I'd fully weld one side, and leave the other as is. 
So if it needs to move, it can move. rather than welds both side shrinking as they cool and trying to pull the pin from both ends. Then cracking or whatever.
It's probably all splitting hairs anyway.
You cant really tell from the pic, but the weld pool is very shallow, it's only sayyyyyyy 1/10th of the way into the rocker.
But I now have 23x rockers that are one side welded. 
All of them turn freely and seem fine. 
All I need now, is a 24th rocker. And an engine to put them in. Haha.

[Roman]

I wont have another 4GR motor until at least the end of Feb.
However in the meantime a very cheap FWD 2GRFE came up.
It was missing a bunch of stuff, and it looks like it's never had an oil change...

This was a good buy for a few reasons.
One of which is to be able to compare the cams.
To 100% check if aftermarket Kelford cams will fit the Direct Injection engines.
So all of the dimension etc are the same, phew!
Just nothing to run the (now removed) DI pump.



This motor also has the bellhousing pattern that is similarish to the 3S - So I can see how an Altezza bellhousing will fit.
Then I can see if it would have actually bolted up how I was intending at the start of this project.

Something else that I have confirmed by pulling the 4GR further apart. 
Is that the 4GR does indeed have exactly the same length conrod as the 3GR and 2GR. 
So they are all 147.5mm center to center. The motor deals with the reduced stroke length by adding more compression height to the top of the piston.
To account for 6mm stroke difference, the piston only needs to be taller by half that much.
So ideally it would have a longer rod. But it's good news in that the plethora of existing forged 2GR rod options will fit any of the motors.

For research and dissection purposes. A friend is dropping off a 2MZFE to my place, some time in mid February. (Thanks Adeel)
This is the 2500cc V6 from the previous generation, that has the shortest possible stroke crank that might fit.
It has a 69.7mm stroke, same as the China only 5GR motor.
The crank appears to be identical dimensionally to GR engines, apart from having a different part slotting onto the nose of the crank for chain vs cambelt.
This will be the cheapest and easiest way to repeatably source a sub 70mm crank.

So, keeping in mind the above.
It's actually some cool news that all of the GR motors have the same length rod. 
Because if I design and make some conrods to work with a destroker crank.
The same rods and crank combo will work with a 2GR, 3GR, or 4GR.
With the short crank and longer rod you get: 
2GR: 2800cc
3GR: 2500cc
4GR: 2200cc
Then it also means that any aftermarket forged pistons, currently available for a standard length rod. Will work with the destroker combo.
So for only doing 1 job it unlocks a lot of options.

A 69.7mm stroke engine reaches 5000 ft/min (Same as Echo was doing at 9000rpm) by 11k rpm instead of 10k.
Or more to the point, 10k rpm would only be around 4500 ft/min which is quite a conservative max speed.
Not that any of this matters if the heads want to blow to smithereens well before that. 

Onwards with the meaningless suffering 

[Roman]

Still waiting for $$ for another motor. But have been doing some side-scheming.

It seems that the rocker and lifter geometry is not necessarily a Toyota specific thing. 
Measuring up the hydraulic lifter, and it seems like nearly everything else with a similar setup (BMW, VW, GM, etc) uses the same stuff, or at the least largely the same dimensions.
As in, they are all 12mm diameter and then just vary height slightly based on application.
Then some of the rockers look the same too. 

In order to use the clips that clip the rocker onto the hydraulic lifter though. You either need to cut some slots into the top of the lifters, or swap them out. The aftermarket kits for the 2GR look to just be OEM lifters and clips from the Coyote 5.0 V8 which has a near identical looking valvetrain.


 

Some guys are revving these Coyote motors to big rpm so that's good news I guess.
They're fairly expensive to buy 24x lifters and rockers brand new though.

So I've been having a look around for a second hand set.
The N52 BMW engine is a straight 6 with 24x lifters which are already circumsized for the clips.

2GR vs N52:
 

The BMW lifters are 2mm shorter, which I dont think is an issue - as I've also been looking into the idea of shimming the underside of the lifters, so the hydraulic action is doing the absolute minimum. 
As people have mentioned that doing it this way works just as well as completely solid lifters, but you dont need to do the incredibly fiddly job of setting the valve clearance by swapping out the valve stem tips.

Although, that is another option. 
The 2UR motor, which is basically a V8 version of the 2GR. Shares quite a large amount of the geometry between them.
They use the same length/dimension conrod on both engines. The rocker arrangement is largely the same. 
But the 2UR has a fixed pivot point, rocker clips, and then shims the clearance with valve stem caps that you can buy from Toyota in varying sizes.
So that's another option perhaps. 
I've bought one of the solid pivots to test with my spare head. It looks like it will need some machining to make it work though. 
Unfortunately in the parts database it doesnt list the clips on their own. Only the rocker or the pivot. 

 

If the BMW lifters/clips fit onto the toyota rockers, that would be most excellent as it was quite cheap to get a 2nd hand set of 24x.
Which should be arriving today or tomorrow hopefully.

[Roman]

This is a Toyota GR engine rocker, BMW N52 hydraulic lifter, and a clip from a random 4 cyl Peugeot at pickapart. 

Whatever works, right? haha.

The BMW stuff came with rockers, lifters, and clips. 
However they have a longer rocker, and the clip is like thin wire rather than a sheet. So it wont fit on the shorter 4GR rockers. 
However it was worth getting them for the lifters that accept the clips.
The peugeot clips work nicely with both, with just a small zing on the end of the rocker to let the clip seat nicely.
Looks like a workable combination, just need more of the clips.

It looks like Barra or similar Ford I6 engines have clips that are largely the same.
So I'll try find some of those, as they're probably a lot more common than Peugeot stuff. 
If anyone's got a broken motor sitting around with a bunch of clips that look like that, let me know!

[Roman]

I got a new motor! 
A real nice one this time, 90,000km on it.
This is from a Gen 2 Mark X, which supposedly had some improvements to the PCV system and piston rings. Soit ends up with less shit all over everything in the intake.
The state of the valves/ports was MUCH better than the earlier engine from last time.
Hard to even know what's there, with all the shit on top as it comes from factory:




It's been time consuming to get it ready to go, because it needs to be stripped down to a bare block.
I've done a few things a little differently this time but the to-do list:

-Swap to front sump setup
-Remove heads, fit Kelford valve springs and retainers
-No porting the heads this time (Will be interesting to get a base line with standard vs ported later on)
-No plugging the DI holes time (Will leave factory injectors held in place, filled with resin so they cant blow open)
-Swapped intake/exhaust 
-welding the rocker pins
-Fitting BMW hydraulic lifters with Barra rocker clips
-Adding the VVT cover plates, and loctiting all of the VVT pulley bolts.

I've finished one side, and the head is bolted back on. 
Just need to finish the fiddly job of refitting the valve springs, then the other head can go back on. 
Exciting!

[Roman]

The new motor is back in the hole, and so far so good. 
Last time I got as far as running the car through the gears up on stands to make sure everything was working. 

So this time more of the same, but since the motor hasnt crapped itself. 
I've been dialling in some of the low load areas just by running the car up in 5th gear. 
With a blip to 8900rpm for good measure. EDIT: not 89,000rpm, haha.
 

Yes, I need to tidy my garage up. But was full of fizz to just get this running haha. 

Anyway, some observations so far. 

1. When the fuel is a bit more dialled in, the throttle response is SNAPPY! 
As in, mega snappy. It's gonna be awesome I reckon. Feels a lot more snappy than 1NZ did. Hopefully it's not too touchy on first blip of the gas.

2. I got the hot idle sorted and stable, idling at a nice 750rpm no problem. Then have run it through a few iterations of trimming the warmup enrichment. Now it starts nicely off the key, with no foot on the gas even when cold. Excellent.

3. I've been having a weird issue where after cranking, one of the widebands stops responding on canbus.
But if I unplug/replug in then it works again. 
I've got a spare relay in my fusebox, so I'll hook them up to that.
So I can just have them come on shortly after the engine starts. 
Which is probably the better way to do things anyway. 

4. Currently at idle there is around a 10% imbalance bank to bank, in wideband readings. 
Which is interesting given that there are the air tubes linking two banks together. 
However it might need a little more fiddling with the throttle stops and so on to get it to match. 
Otherwise perhaps I've got a small air leak somewhere, ahead of the wideband on one bank. 
Or maybe a poorly performing injector. 
Will narrow it down and figure it out. 
It will be interesting to see if the problem goes away once the throttle % goes up.
As that indicates a different sort of issue either way. 
I can make a compensation table in the ECU to get the air fuel ratios fixed up anyway, if long term they are slightly problematic at full throttle conditions.

5. The way my fuel rails are, the injectors can rotate underneath them 90 degrees either way from their normal position. 
So, when the injectors are in their normal orientation. The widebands will show something like 14.6:1 air fuel ratio. 
If I rotate the injectors 90 degrees, it now shows around 16.4:1 on the wideband. 
Then this is very repeatable. Interesting! 
The injectors must have a dual spray pattern left and right, which changes to top/bottom when you turn the injector. 
It's crazy to see that it affects combustion quality and the reported air fuel ratio so much. 

That's all for now, I need to finish mounting the battery properly and finish the exhaust. Then it's about ready for a bash around the paddock or maybe a trip to the dyno. 
Cant wait to hear it under some load at full chat! 

It feels like I'm getting to the fun part of the project, and where it's fun testing and setting things up. Exciting. 

 

[Roman]

I bought a 3" Adrenaline R muffler, and I've been hoping that just 1x muffler will be sufficient. 
So welded a flange on and bolted it up to the end of the 2-1 section to test it out before committing.
I'd say its probably still a weeee bit too loud (Still need earmuffs on when it revs out) 
So I'll have to try stuff something else in there too. 

This one was filmed with the camera bit further back, and the audio recording level turned down so it wasnt clipping. 
In person it's still ear splittingly loud. 

Currently the ignition timing is all very conservative, as I'm not sure what the motor is going to like with port injection and the 12:1 compression.
Overly delayed ignition timing means more exhaust energy (noise) comes out the back. 
So it will quiet down a bit as the timing gets dialled in. 

Currently there's no VVT advance happening, everything is just at home positions. So from experience the intake starts getting a LOT LOT louder when you start introducing some overlap. 
As much as I do love some incredibly obnoxious intake noise. If it's so loud that it's melting my brain. Will need to make an airbox to calm it down a bit. Ha.

I am still chasing an issue (by which I mean I havent investigated it yet) where the reported voltage to the ECU drops off, when the rpm goes up. 
I am suspecting this relates to a bottleneck at my fuse/relay box. So will do some troubleshooting.

I have officially run it to the 9k mark now, and valvetrain has survived. Haha. So hopefully a bit more left in it yet.
It feels tantalizingly close to being drivable!

I need to make some heat shields in quite a few places. As there is a huge % of the engine bay that is line of sight to the radiant heat emitting from the exhaust manifolds. 




This video is probably a fairly good representation of how the car will sound when it's finished and driving.
 

 

[Roman]

Fizz levels are high but as always I've got problems. Haha.

My throttle pull cable system isnt working well enough to synchronize the banks.
It will do weird shit like... Both throttles start at 10%. Blip it up to 30% throttle, one will land at 10% and the other at 12%.
One will land at 0% and one will land at 2%. Then blip it again, and both at 0% (or whatever)
Then the imbalance ends up different depending on things like how quickly you push the pedal, and whether throttle angle is increasing or decreasing. weird.
So its not like I can just make a compensation table for it.

After a bit of head scratching I think it is because of the springyness of the cable itself.
I'm trying to wrap a springy cable around 2x tight radius pulleys by varying amounts.
The more wrapped around it is, the more it wants to try unwind itself back out straight.
So this does chaotic sort of things to the TPS position of the second bank.

In terms of full throttle tuning/power, none of this stuff is really too much of an issue as I could simply set end stops that both sides bang into. 
But it causes an unacceptable level of problems below that.
I dont want to spend a massive amount of time chasing my tail on this when it comes to tuning time. 
Especially if I'm trying to make my 2025 deadline to take it to @kpr

I could switch to using dyneema rope for the linkage cable, so that there is zero springyness and zero backlash.
This would likely all work fine.

BUT 

Cable throttle was all just meant to be an interim measure to quickly get the car going, before changing to ethrottle later on.
Now that I'm balls deep in pondering the many complexities of cable based bullshit.
I am looking back in the direction of ethrottle again.

Ethrottle will just keep moving each side until its exactly on target (or very close anyway) 

So just for a refresher for what I've unsuccessfully tried already: 
-Dual Triumph 1200 throttle banks. Would have worked nice, but port spacing wasnt good. 
-half arsed attempt at pushrod setup
-Bulldozer ethrottle. Too huge, lacked some safety features, cables way too long, whole thing way too big
-Holden cruise control unit. Looked good, but had a stepper motor inside and complicated electronics.
-cable based bullshit

I've now found a new set of magic beans ethrottle option that I am hoping will work well to pull the throttles open.
Which is the cable based traction/cruise system from an E36 BMW. Which looks like this:



The reason I think this one might work where the others havent.
The motor has a 2 wire plug, so I suspect that it is a straight DC motor.
No brains in it, no TPS, no speed signal, no stepper motor. 
The motor is totally divorced and just has 1 job which is to pull a cable. which is exactly what I need.

I ordered a pair of these from ebay so they're a few weeks away unfortunately. But will be cool if it works.
My current cable based setup needs both pulleys on the same plane, which meant they had to go way out front of the motor.
But these could instead mount these down the back, or offset from each other if needed. So it's all out of the way. 
So then the path is more clear out the front for my future airbox scheme.

I'll carry on workin on the exhaust and trying to figure out the voltage drop issue until these arrive.

If anyone locally has one I could borrow to test with until these others arrive. Would be appreciated!

[Roman]

Ethrottle? No.

Tuned decently? No.

Exhaust hung properly? No.

Car finished? No. 

Skids on lawn? Yes