My E30/R5Turbo track car - Gearbox MkIII

[German-Whips]

[GeoffBob]

Brilliant stuff Geoff! My old Corsa A sounded the absoloute bollocks with the straight cut box, had 45mm TB's too. Made me glad to be a man lol.

Ooooh Yehhh, fully agreed - definitely improves ones manliness index for the day.

Don't they sound great when you lift off and engine brake?

Mine screams so loud it sounds like its trying to give birth to something. Hopefully not a pile of cogs on the ground

Just out of interest, how old are you? Thought you'd be late 20s to early 30s.

Not far off, I'm 38.

Whenever i get a new car, i improve it and tweak it and upgrade it until eventually, i've ruined it and it's no good as a means of transport any more!

Story of my life

In all seriousness Geoff, I'd rather keep the M3 largely a road car, that is capable of trackdays when needed. With this in mind, as epically heroic the car would be with a straight cut box, it just isn't practical. Plus I like the idea of keeping as stock looking as possible, having it whine like a bitch when pottering around car parks on tickover just isn't really that stealthy

In full agreement Chris. Unless she's a 100% track car it's just not practical to fit a box without synchroniser rings, regardless of whether the gears are straight or helical cut. I have snuck out at dawn (before work) two mornings in a row (Monday & Tuesday) for a drive around the neighbourhood. Not at speed, but purely to practice double-clutching on my downshifts. Get it wrong and the gears grind and snarl back in anger. And that's no way to negotiate your way around a car park.

[GeoffBob]

BTW, anyone here read the book Going Faster by Carl Lopez? Quite a few I would imagine. It's one of those books I keep next to the bed to remind myself (before I go to sleep) how I am supposed to drive on the track. Chapter 6 specifically deals with shifting gears, more specifically with down-shifting on a unsynchronised gearbox. For someone in my position (new to race gearboxes) the content of that chapter is pure gold! Now, if only I could remember to lift up off the clutch before I blip the throttle then I might stop grinding gears.

Anyone here mastered the whole heel-toe double-clutch manoeuvre?

[e21Jason]

Leanign to drive in sh*t cars and having an mg midget with no syncro on first (that's the way they made them) and an austin 7 to play with as a teenager helped with the double de-clutch.

Also i found the skip barber how to drive book a very good balance between theroy and application. But nothing has been better than some 1 to 1 instruction, only done about 1/2 day but plan on a couple more sessions, so much to take on board harder than getting my head around Laplace transform's when i was at uni.

Jason

[GeoffBob]

Also i found the skip barber how to drive book a very good balance between theroy and application. But nothing has been better than some 1 to 1 instruction, only done about 1/2 day but plan on a couple more sessions, so much to take on board harder than getting my head around Laplace transform's when i was at uni.

Agreed. I am currently looking for someone local who has experience with non-synchro gearboxes. In fact, I'll be at Zwartkops tomorrow with Veron Pappas, the person who hobbed my gears for me. He races a Speads single seater and will hopefully provide me with an afternoons worth of tuition. He agreed to come along with me as he is keen to see/hear his gears in operation. If the gearbox breaks he gets to clean up the oil

I know I'm not supposed to do it, but for those interested I have PDF'd chapter 6 of Going Faster by Carl Lopez (the Skip Barber Racing School handbook) here. Anyone interested in learning how to double-clutch along with me, just do the whole right-click and save-target-as thing. It's only about ten pages (5.45MB) or so that will hopefully encourage some to buy all 277 pages of the book here

[Ziggy]

Nice one - perhaps a refresher will enable me to get it to feel more natural. & if it works, buying the book will be fair as well as useful!

[GeoffBob]

As promised, I took the car to Zwarkops again yesterday (I try to do at least one Wednesday per month). I booked the car onto Braam Mullers Dyno for the morning to get the fuel and ignition maps tidied up. The results speak for themselves.



Shown below is brake horsepower (hp) and torque (Nm) at the flywheel (an odd mix of units, but apparantly the locals prefer torque in Nm to lbs.ft). I'm generally happy with Metric OR Imperial. A mix of both seems somehow odd.



As you can see, the engine made 450hp of power and just over 600Nm of torque at the flywheel at 5100rpm on 95 octane pump fuel. Not too shabby if I do say so myself. I can honestly say that I had not expected to make it over 335hp as a result of previous efforts with this engine. The redesigned manifolds (inlet and exhaust) as well as the GT3267 turbo have made a big difference. So much so that I have now run into issues with the internal wastegate that I had sized for the lower power figure . I will thus be fitting an external wastegate in the near future. Fortunately I do have room for one. The fact, however, that I am using a twin-entry turbo does make the plumbing to the wastegate a little more complicated, but I'll manage somehow. I also need to look at running the engine on proper race fuel as a result of detonation creeping in above 1-bar of boost. Braam had to back off the throttle above 5000rpm to control this, so the above graph is by no means a full indication of what my car can achieve.

Oh, and before I forget - No smoke out the back of the tailpipes (bar the occasional puff as Braam came off the throttle) and not a drop in the catch tank! I am very pleased with the result.

Shown below is a graph of the wheel power and torque.



Taking the car off the dyno unfortunately revealed a moderate sized pool of oil under the car. I was too cheap to replace the copper washers around the banjo-bolt where the oil feed to the turbo connects to the block. I tried to tighten the bolt but stuggled to get at it around the extremely hot exhaust manifold. So I took the car onto the track anyway, where I was promply black-flagged for excessive smoking - this time most definitely as a result of the oil collecting on the exhaust. A quick look under the car after I came into the pits revealed that the two flex-hoses (the type with wire braiding around them) seemingly act as a sponge, collecting much of the oil that drips from the engine. It quite litterally appeared as if I had two smoke grenades strapped to my exhaust . Never a good idea to smoke out the poor sod in the car behind you.

Too add insult to injury, I took along a borrowed video camera (gaffer taped, Heath Robinson style, to my cage) which produced the most beautiful video footage of the track in front of me, but with no sound! Aaaaaarg . Next time I'll plug an external microphone into the camera. I have no idea why the microphone on the camera didn't work.

The gearbox performed beautifully BTW. I was primarily out on the track to practice my downshifting and I eventually became quite good at it if I do say so myself. I spent the remainder of the afternoon, after being black-flagged off the track, buzzing around one of the deserted areas of the parking lot. So long as I blip the throttle while double clutching between shifts, then the box shifts down without so much as a grunt or groan. Now I need to start focussing on up-shifts. If the rpm on the engine aren't falling fast enough between up-shifts the I am going to have to look at lightening the flywheel. If the rpm are falling off too fast then I just need to learn to up-shift faster.

All in all an excellent day. I still have much work to do to get my little race car race-ready, but I am now closer than I ever was before, and that means I am making progress!

[Theo]

Holy crap, epic power!

Great read as ever, really pleased to hear that the gearbox is living up to expectations. It goes without saying that I'm hugely jealous.

[tim_haynes]

Geoff hugely impressive, very pleased for you, QUALITY CAR!!

[maxfield]

Awesome just awesome.

[gareth]

Well done that man! You've created your worst car yet, and i'm insanely jealous!

I wonder how much power is possible on race fuel?

[Mikey_Boy]

Excellent stuff Geoff - really well done! Just looking at the power curve and I am wondering why your torque peaks so late? Is that deliberate to give your gearbox an easier time and make the most of your close gearing? Or is your turbo large to give you that excellent power figure? Just wondering if you can put a dollop more boost lower down to give you a fatter torque curve and a bit more shove out of tight corners? More boost low down won't hurt pistons too much, you can chuck a fair bit of boost in and take a bit of spark out without going sky high on cylinder pressures and get a useful gain in torque.

Incidentally, what type of wastegate are you running currently?

Excellent news on the oil catch tank front - that you are getting nothing in the tank shows that your oil breathing is now much much better... I shall look forward to my Christmas card!

Cheers,
Mike

[martinpallot]

Awesome power there but I cant help but think the drivtrain losses are a bit steep considering the straight cut box? Correct me if im wrong but most standard bmw's ive seen on the rollers probably average about 15% loss with a helical box. Yours looks around 20%. Im intrigued?

[GeoffBob]

Thanks to everyone who replied above. I'll refrain from personal replies if that's OK as I have rather a lot on my mind at present.

I sat down for the first time last night to analyse the above two dyno-graphs and came to the conlcusion that the graph of flywheel torque and power (the first graph I posted) is utter rubbish!

Firstly, there is just no way in hell my turbo can flow enough air to support 450hp at the flywheel. Secondly, the difference between the two graphs (flywheel power - wheel power) indicates that my engine would be putting nearly 100hp into the drivetrain alone (gearbox, diff etc). On a gearbox without an oil-cooler, not a chance! And I felt the gearbox, it was hot to the touch and that was it.

At the end of the dyno session I asked for a plot of the drivetrain losses, which I was given. For those that don't know, drivetrain losses are recorded by the dyno at the end of a power run when the operator puts his foot on the clutch. The dyno computer then measures the speed of the rollers as a function of time to determine how long the cars drivetrain takes to drain the angular momentum of the rollers. From this info the dyno can calculate the actual power that the drivetrain will drain from the engine at any given rpm. That plot, which you can just see at the bottom of the second graph (I have a larger paper copy) indicates that my drivetrain is draining roughly 22hp from my engine at 5000rpm. That means that my flywheel power should equal (roughly) 350hp (at the wheels) + 22hp (lost to the drivetrain) = 372hp (at the flywheel). Now, that figure makes sence to me! That figure I can understand because that value is corrected to sea-level and I am at an altitude of 5500ft. Our daily barometric pressure is around 0.85 bar and our tempratures usually high. That means that the measured 372hp (corrected to sea level) easily equates to 335hp up here on the highveld.

So, just where the hell did Braam get 450hp from? I crunched the numbers last night and his flywheel graph equates to exactly 1.18 times the wheel graph + the transmission losses. So what is this 18% add on? VAT? Maybe he thought he was being nice by giving me something to brag about?

The miserable tosser. I am so angry . Doesn't anyone realise that it's the accuracy of the data that counts. I need this data to verify my calculations, not so I can brag. I'll take an acurate value any day over a value that is bigger than my neighbours. If all I wanted was a big value I'd draw it myself with a wax crayon on a bit of cardboard.

Any and all inputs appreciated please. If there is someone out there who knows their way around a dyno please enlighten me. Maybe I am mistaken in my understanding of either of the above graphs or in my understanding of transmission losses. I mean come on, 100hp into a gearbox with no oil cooler. Yeh, now pull the other one.

[GeoffBob]

Awesome power there but I cant help but think the drivtrain losses are a bit steep considering the straight cut box? Correct me if im wrong but most standard bmw's ive seen on the rollers probably average about 15% loss with a helical box. Yours looks around 20%. Im intrigued?

Martin - you are spot on! Iwas typing up the above post when you posted yours. This is exactly what I spotted last night. According to the "drag" graph the engine was losing 22hp at 5000rpm to the drive train. But that's not what the difference between flywheel and wheel graph says ????

There's something funny going on here and I am going to get to the bottom of it!

[GeoffBob]

Just looking at the power curve and I am wondering why your torque peaks so late? Is that deliberate to give your gearbox an easier time and make the most of your close gearing? Or is your turbo large to give you that excellent power figure? Just wondering if you can put a dollop more boost lower down to give you a fatter torque curve and a bit more shove out of tight corners? More boost low down won't hurt pistons too much, you can chuck a fair bit of boost in and take a bit of spark out without going sky high on cylinder pressures and get a useful gain in torque.

Thanks for the input Mike. I have an electronically controlled boost controller connected to the wastegate actuator that I have set to climb smoothly and progressively (almost like you would get from a centrifugal blower). The punch up the backside (around 3500rpm) was too much for me to control otherwise. The smooth boost curve (although less than what the turbo can deliver) constitutes my "training wheels". If it weren't for the fact that Braam was modulating the accelerator pedal (in other words, not running WOT) after 4500 rpm, the torque should have climbed some more and peaked even later.

Incidentally, what type of wastegate are you running currently?

The stock internal wastegate on the GT3267. Rated for 200 to 400hp, another reason why I don't believe that I was making 450hp! The 64mm diameter turbine chokes at 20lbs/minute. 20lbs of air per minute is good for roughly 200hp! So, to make it to 450hp I'd have to flow another 25lbs per minute of air out through my wastegate. Like hell!! Besides, 45lbs per minute of air is right off the right-hand side of the compressor graph. The bearings would cook at that speed.

Is it possible I have stumbled upon the dark seedy underworld of dyno-operators (henceforth to be known as "power pimps").

[Jon_Bmw]

The graphs are quite funny, they are exactly the same, just with a different scaling!

It is probably an intertia dyno, like my dynojet as ours can also give the coastdown losses but we don't use them as back to back with our engine dyno it isn't very accurate. If we do show coastdown losses as some customers are rather insistant upon, they are shown as a negative graph, which follows a similar pattern to your wheel graph losses(But inverted about the horizontal basically).

If you believe the wheel HP graph it is still a pretty pokey motor you have got there.

The graphs also look funny because the torque doesn't intersect with bhp at 5252rpm, but this is because it is NM(facepalm) and not lb ft. Crazy locals!

[GeoffBob]

The graphs are quite funny, they are exactly the same, just with a different scaling!

Correct. Is that not as one would expect? Transmission losses are (to a first approximation) a linear function of engine speed. One would thus expect the two graphs to have the same basic form, but have different scales?

It is probably an intertia dyno, like my dynojet as ours can also give the coastdown losses but we don't use them as back to back with our engine dyno it isn't very accurate. If we do show coastdown losses as some customers are rather insistant upon, they are shown as a negative graph, which follows a similar pattern to your wheel graph losses(But inverted about the horizontal basically).

That's the one. It's an inertia dyno with an eddy-current brake. He uses the eddy-current brake to load the engine while tuning, but not while doing power runs. The "drag" graph, as he called it, is the "coast-down" graph the you refer to.

If you believe the wheel HP graph it is still a pretty pokey motor you have got there.

Thanks Jon. I am inclined to believe the wheel graph as it's not far off what I calculated. But honestly, that flywheel graph is utter nonsence.

The graphs also look funny because the torque doesn't intersect with bhp at 5252rpm, but this is because it is NM(facepalm) and not lb ft. Crazy locals!

Agreed, as per my earlier comment. The relationship between torque and power is correct though, I did check that, even though the use of mixed units is quite nutty.

[e301988325i]

Anyone here mastered the whole heel-toe double-clutch manoeuvre?

I wouldn't say mastered, but I can get it right most times in lowly populated areas where I won't upset too many people blipping the engine. It feels awesome when it goes right. My pedal spacing and brake pedal height and feel is perfect fot it, and adjusting this pays dividends.

The really tricky thing is not revving higher when you press the brakes a little further.

With your custom EVENLY spaced ratios you should be able to work out how high to blip the engine each time, and this should be very close similar for each gear, although 4th to 3rd will always be faster than 3rd to 2nd, and some adjustments must be made for that.

The other trick I find helpfull, going from 3rd down to 2nd is to push the lever to the left so I only have to pull back when I put the cluch back down after blipping.

Ps) Awesome build!

[GeoffBob]

I wouldn't say mastered, but I can get it right most times in lowly populated areas where I won't upset too many people blipping the engine. It feels awesome when it goes right. My pedal spacing and brake pedal height and feel is perfect fot it, and adjusting this pays dividends.

The really tricky thing is not revving higher when you press the brakes a little further.

Indeed it does feel awesome when it goes right. If it goes wrong, however, the dog teeth groan quite loudly. I can't help wondering how long my box will last till it needs a rebuild? I use my heel to blip the throttle following the traditional heel-toe manoeuvre. That way it really doesn't matter how far the brake is de-pressed at that time. I deliberately made my throttle pedal quite long so that I could do this (see pic below). I find this easier (personally) than trying to role my foot over the brake and using the side of my foot on the throttle. Having now begun practising the whole heel-toe bit I think I need to move the throttle pedal a wee bit closer to the brake pedal.

With your custom EVENLY spaced ratios you should be able to work out how high to blip the engine each time, and this should be very close similar for each gear, although 4th to 3rd will always be faster than 3rd to 2nd, and some adjustments must be made for that.

So long as I take note where my rpm are before I shift to neutral I can estimate where I need to rev to when I blip the throttle. This has helped me a bit, but occasionally I take the revs too high and then I simply "feel" the dogteeth against each other as I try to snick the gear into position. As the engine revs drop to the point where the speed of the lay-shaft (counter-shaft) matches the speed of the main-shaft (output-shaft) I can feel the teeth just slide into place. Quite a good feeling actually

Awesome build!

Ta

[e301988325i]

Great minds think alike!

Indeed it does feel awesome when it goes right. If it goes wrong, however, the dog teeth groan quite loudly. I can't help wondering how long my box will last till it needs a rebuild? I use my heel to blip the throttle following the traditional heel-toe manoeuvre. That way it really doesn't matter how far the brake is de-pressed at that time. I deliberately made my throttle pedal quite long so that I could do this (see pic below). I find this easier (personally) than trying to role my foot over the brake and using the side of my foot on the throttle. Having now begun practising the whole heel-toe bit I think I need to move the throttle pedal a wee bit closer to the brake pedal.

I would suggest a magnetic gearbox sump plug, and checking it regularly, I would estimate as the dogs get worn, it will slip out of gear under load and require more of a remanufacture than rebuild . However I have the luxury of synchro's to cover my failings, but I'm sure the feeling of perect engagement is no different between the two.

I'm sure that where the pedal hinges has more to do with styles than personal taste, the stock E30 pedal is floor hinged, so it moves very little where your heel sits, for the record I roll my foot (although you clearly understood this)

So long as I take note where my rpm are before I shift to neutral I can estimate where I need to rev to when I blip the throttle. This has helped me a bit, but occasionally I take the revs too high and then I simply "feel" the dogteeth against each other as I try to snick the gear into position. As the engine revs drop to the point where the speed of the lay-shaft (counter-shaft) matches the speed of the main-shaft (output-shaft) I can feel the teeth just slide into place. Quite a good feeling actually !

Best in the world, and you'll never do that with a slush box or semi-automated manual of whatever description.

I'd love to have a play with a dog box, well so long as the owner couldn't hear my practising! I'd also love to play with a mechanical sequential box !!!

[Mikey_Boy]

Hey Geoff - thanks for your reply on your wastegate - let me have a think about that - looking at the power curves again I can see your frustration that things aren't as accurate as you might think which is not the best for you of course!

But take heart from the fact F1 teams also get it wrong as well - badly calibrated dynos and bad results have led to a lot of wasted money on engine development dead ends due to human error so you have done a great job spotting the error when you did... Your patience will pay you great rewards!

Cheers,
Mike

[Jon_Bmw]

If you just work off wheel HP and only use that dyno, it doesn't matter (too) much if the dyno is inaccurate. Because you now have a base figure to work from. It only matters if you start to compare it to other peoples cars(down the pub ) or you need a graph for race regulations(power to weight).

Out of interest, given the spec, the wheel figure seemed to be pretty much on the money.

Did you watch him tune it using the retarder(eddy current brake)? The reason I ask is:

On our dyno, when mapping a car which is just coming on boost at say 2500rpm and you have the load control set to 2500rpm, the dyno goes beyond 2500rpm, then 'struggles*' to bring it back down, then it drops to just below 2500rpm and the car goes off boost and the revs drop. It is a viscous circle. ARRG! Good predictive mapping and various TPS 'pulls' with logging allow you to get it pretty good in the end though.

Given yours is probably going to come on boost rather rapido, I thought i'd ask.




*it doesn't really struggle, just take a few seconds which is annoying.

[GeoffBob]

[GeoffBob]

Hey Geoff - thanks for your reply on your wastegate - let me have a think about that - looking at the power curves again I can see your frustration that things aren't as accurate as you might think which is not the best for you of course!

But take heart from the fact F1 teams also get it wrong as well - badly calibrated dynos and bad results have led to a lot of wasted money on engine development dead ends due to human error so you have done a great job spotting the error when you did... Your patience will pay you great rewards!

Cheers,
Mike

Thanks Mike. I'm afraid I'm a bit of nutter when it comes to getting my measurements to match theory. Having accurate data is the only way that I can verify my calculations. If I can't get performance to match theory then it tells me that I need to upgrade the theory, and (ultimately) having that little bit extra understanding may very well give me the edge that I require. I have a data aquisition unit that I will be fitting to the car when I finally get to that point, and my ECU already has it's own data logging facility. I hope to eventually monitor pressure and temperature at a number of points along the intake and exhaust system as these parameters relate very strongly to the behaviour of the engine, and help hugely to verify the theory (which is really only just an implementation of the laws of thermodynamics and fluid-dynamics applied to a practical application). The data (logged on the ECU) from the other days dyno session was enough for me to improve my model of my engines volumetric efficiency, which was (until that point) only an approximation. Until the other day I had no actual data to determine the effect of the new intake and exhaust manifold upon the engines VE. Now I have that info,

'Been reading some of your other posts on here Mike. Correct me if I am wrong, but I suspect that at some point in time you were an engineer on an F1 team, or for a company that built the engines for one of the teams? I would love to hear more about it if I am right? Only just about my dream job in the whole world.

[GeoffBob]

[Mikey_Boy]

Hi Geoff - guilty as charged! I was an engineer for Cosworth, Roush and Ilmor in the early part of my career and then worked with the Ferrari F1 team trackside for 4 years running Shell's technology programme for Motorsport (Ferrari, Ducati and Audi Le Mans).

I am still with Shell but not in F1 anymore, but still getting to play around with technology. Also diverting my limited engineering skills into my trackday car!! Very impressed with your knowledge of alternative fuels by the way!

I hope everything is coming together with the engine - drop me a PM if you want to bounce some ideas around on instrumenting your engine - if that goes boo-loo, then you are going to be tearing your hair out with the mismatch of theory and practice!! As 1 of my mentors says - getting results is a pice of cake, getting the right results is the challenge! Also, looking at your threads above, I think you would really benefit from some engine dyno time...!

Cheers,
Mike

p.s. You have a great 'rolling CV' with your trackday car - I am sure racing teams would be interested!

[rix313]

..Any and all inputs appreciated please...

This maybe of some interest to you Geoff:

http://forums.m3cutters.co.uk/showthread.php?t=7378

[GeoffBob]

[GeoffBob]

Oh well, back on the job this weekend All my bits to fit my external wastegate have arrived so it'll be off with the manifold and head down at the welding table this weekend.

[Mikey_Boy]

The external wastegate will be well worth it.....! Only pesky packaging reasons why they aren't used more by the OEMs.. I have an uprated external wastegate on my (old) Porsche turbo and that makes one heck of a difference in terms of boost control on tip in of the throttle and (more importantly) tip out - much better response and drivability and all for the same boost...

Let me know about instrumenting as well Geoff when you get the time - after you have done the wastegate, there may be a few ponies and better throttle response in there if you optimise the intake side as well - more for you to think about!

Good luck with it!
Cheers,
Mike

[GeoffBob]

The external wastegate will be well worth it.....! Only pesky packaging reasons why they aren't used more by the OEMs.. I have an uprated external wastegate on my (old) Porsche turbo and that makes one heck of a difference in terms of boost control on tip in of the throttle and (more importantly) tip out - much better response and drivability and all for the same boost...

Mike, I've bought a 46mm external wastegate. I've also asked the local Garrett agent for a quote on a GT3071R. The turbine is slightly smaller than my GT3267, with a slightly larger compressor. This the turbo that I originally wanted on my car but couldn't afford it at the time. The GT3267 was half the the price due to the fact that it's a journal bearing turbo. I was also attracted by its internal wastegate. Looking at the both the turbine and compressor maps, there's little between the two. The GT3071 turbine is specifically free-floating (no internal wastegate).

In the mean time I am tempted to fit a local T3-3 A/R=0.48 with a T04E 75mm trim 57 compressor wheel, just to see what happens. These are dime-a-dozen locally and used to the extreme by those who frequent the local drag strips. Despite their friendly price, I am not a fan of these as the compressor maps that litter the net seldom match the product that is being offered over the counter. The quality of the castings also leaves something to be desired. On the otherhand, parts are cheap when they fall apart (which is usually quite regularly).

[Mikey_Boy]

All good stuff Geoff - you are right to be cautious with getting maps from the internet...! off the top of my head, the turbine / T04E compressor combination you describe should flow quite a bit of air...

Hopefully I am not stating the obvious here, but remember that the best way to get a compressor to behave itself is to ensure the turbine is as unrestricted as possible - that, is the largest exhaust downpipe you can get on. Once that is done you can focus on optimising the intake side (airbox to compressor, compressor to intake manifold) which makes a HUGE difference to response...

What are your concerns about bits falling apart???

[GeoffBob]

Hopefully I am not stating the obvious here, but remember that the best way to get a compressor to behave itself is to ensure the turbine is as unrestricted as possible - that, is the largest exhaust downpipe you can get on.

No worries Mike. I currently have a 2.5" downpipe (matching the 60mm turbine outlet) which splits about a foot down from the turbine into two 2" tailpipes. With the new wastegate and turbo I plan to ditch this system (not that it under performs in anyway, I just have no requirement for it on a racecar) in favour of a single 2.5" inch exhaust and 2" screamer pipe straight out the side! No more testing the car around my suburb once that's done, but then she's almost a fully fledged racecar now so I really shouldn't be sneaking her onto the streets. The noise from the exhaust really won't bother me as I doubt I'll be able to hear it over the noise from the gearbox

Once that is done you can focus on optimising the intake side (airbox to compressor, compressor to intake manifold) which makes a HUGE difference to response...

Mike, have you seen the size of the plumbing on my car? The cone filter is mounted in a high pressure zone cut into the front bumper. The 4" pipe work from that runs straight (and I mean straight) to the mouth of the turbo. The intercooler, and the inlet and exhaust manifold are my own design. Not to be too big headed, but I am not sure there is much optimizing left to do. The only parts left from the original 3SGTE (but not to say unmodified) are the head, block, crank and cams. I'd do the cams too if the stock ones weren't already very good.

What are your concerns about bits falling apart???

All our local turbochargers are knock-offs from China. If you want a genuine Garrett you have to specify otherwise the dealers simply assume you are talking about a generic part. It's a sad state of affairs TBH. Very often, "blank" compressor and turbine housing castings are brought in and then machined locally to fit the specified wheel. The quality of the machining on these items is questionable. And of course your average Joe has no way of recognising that his newly purchased turbo is underperforming. And if the bearing fails the supplier simply blames the users oil supply to the bearing.

They may take a while to land, but I'll take a genuine Garrett GT turbo over any other brand (or no-name brand for that matter) any day.

[Mikey_Boy]

Hey Geoff - just had a look through the pages of this thread and you are right as usual - all looks great!

Good luck with the hunt for (genuine!) Garrett parts - does seem a pretty dodgy situation!