Roy

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You are all missing the point. Odds are it would be cheaper to get the thing through the corners quicker...then you have more revs on exit and more revs means more power. So what suspension and tyres/rims size are you running. Cams or no cams -5s can work perfectly well on a 2.6L so if the thing is laggy on exit I think you need to get through the corner quicker

Isnt Canada quite hard for tyre wear though...surface wise?

Huh...where is the seat? I may beat you to having a complete car yet ! I am pumped that you are pumped!

I am told outside of GP weekends its quite dirty and shitty place to visit?

You missed the apex!

As Paul says...gear it like a rotary.

So 440 Universal or Link G4 Storm for a built YB Cosworth with about 460hp A bit gutted to be changing the Pectel ecu but need something with more accessible software for some more mods and tunability

I am going to rip this place a new a55hole. Front end will be fixed even if the rear end and shocks wont be sorted.

My 2c is nothing will happen. Suspended sentence. Merc are too big a player as team and engine supplier so politics will get in the way of giving them the reaming they deserve (which is a shame as I am hoping to see Merc have a good few seasons) They didnt know what tyres there were running, but you know it makes perfect sense for the Mercs to have run a few of the current compounds against some of the compounds proposed for introduction this season. The engineers are not dumb and would have had a good idea within a few laps of what tyres they were on. There is also the likelihood that some compounds for next year could have been run but only very initial test as they are having troubles with current tyres, need to get their heads around the changed tyre before they spend too much time worrying about next years tyres when testing with an NA engine vs turbo engine etc etc isnt going to tell them a lot

Less than 1000kms. Mostly dyno time and some street kms to check drivability

It was basically a 20G wheel (give or take) Back to back with the 20G using a 12cm housing and TD06 turbine you would have been forgiven for thinking they were the same turbo when only running 16psi. It hinted at better things in that it seems to do it easier with less ignition and was fractionally more responsive with the same tune from the 20G. But tinkering was stopped as the 12cm housing is obviously hurting it as the T67 with 10cm housing was more responsive and there is something wrong with my engine when I screw 25psi into is doesnt really want to make much more power than 18psi...so suspect valve springs are a problem. So with no valve spring concern and a 1cm housing I would have expected a similar result to you. With a full tune and ignition in its belly woudl havebeen a bit more punchy and responsive and made more power courtesy of being able to effeciently spin it a bit harder with a few more psi, say 26 or so psi Hunting around desperately for a 10cm housing for it and going to put my Tomei valve springs in the engine ion about 8-10 weeks time. Then if the T67 can spin up decent power at 25psi then I will be happy to go back to the 73HTA and spin the bugger as hard as I can . But when capped at 16-18psi and 330rwkws no real point running the 73HTA with 12cm housing when I have other combos that suit the state of play better

Not arguing...just passing on my results with a few caveats. Three curves are - RB20 TD06-20G 8cm housing (call it 0.63) - RB25 TD06-20G 8cm housing (call it 0.63) - RB25 TD06-20G 12cm housing (call it 0.84) Was largely looking at spool and power they would make. Didnt want to spend too much money on dyno time so only rough tune enough to get a feel for where they were headed. Between the 8cm and the 12cm I would go back to the 8cm. My T67 has a 10cm housing and hunting around for an 8cm housing at the moment for it All are my car, same set of tyres. The RB25 is an R32 DE so I used the same 6boost manifold and Turbosmart gate, same Plazmaman plenum and R34 GTR cooler, injectors, PFC etc etc with no VCT. All that changed what the engine which was a truly bolt in affair. GT3071 and TD06-20G are different but not hugely. 68mm vs 71mm compressor and 65mm vs ? GT30 are about 60mm arent they? So different turbos with different trims but its a fair rule of thumb that they generally make about the same power as one another. 20G/3071 and 25G/3076 is not a bad starting point for assessing turbo sizes. If its a street car running E85 then I say just slap on what you have and I think you will find it mega grunty and fun to drive. If you were buying a new turbo then perhaps it is not what you would spec up...but would certainly work and work well (remembering he has the turbo already and its a street car) I am betting it will bag 310-330rwkws depending on what boost is up it and health of engine. Be way mroe grunty then any twin setup running -9s (I would imagine)

My aftermarket rear seal looks a lot better then that one. Bust their balls and get them to try another one that fits waay better! Otherwise now you just need some big anodized calipers. Settling for R34 AP/Alcon combo?

Thats my point. E85 masks the problems associated with higher than desirable back pressure. I agree that I preferred the way the 12cm housing performed on the TD06-20G on a 2.5L but 100% made for a slower car. The 8cm spooled up and hammered in a heart beat. The 12cm made for a lazier thing to drive which is a subjective like it or laothe it thing The below graph shows all the same turbo. Its an RB20 with 8cm housing. Rb25 with 8cm housing and RB25 with 12cm housing. The 12cm housing tunes were pretty rough and ready and boost curves not stressed over. They were slapped on , minimal ignition and just initial power runs to see the characteristics of the turbos before swapping and changing setups and cams etc. But you could get a feel which way it was headed Not all sized turbos and setups would give the same result...but for me a street GTR with occassional track work then I think based on my experience with the smaller TD06-20G and 8cm and 12cm housings I would go the smaller housing.

Nice result. Be interesting to see if you can get it to hold 28psi through the top end. Any thoughts on why it doesnt hold the extra boost in the top end?

4.6 diffs Like you need to go over 240km/h anyway

I stayed away from the R34 rear end as I wanted to run teh GTR alloy hubs and I was told that the bottom of the forked R32 shocks needs to be modded to suit the R34 hubs. I am told that its not a concern when using R33 hubs in an R32. I dont understand how it can be an issue if R33 and R34 shocks are interchangable but I suppose I will realise soon enough if they R33 hubs are going to present me with the same problem. I hope to get some new minter rims son too...I dont like my chances of fitting 295rears and 265 fronts with my current guards. Front is an easy fix but rears are a headache re guard clearnce

That’s about 60% of the story. The other 40% is why carry around the weight of a full exhaust and mufflers. Why take up space around rear suspension and shafts where you want to run fuel cells and diff/trans coolers. Why run the risk of a muffler collapsing and hurting power? So introduces need to life components and expense associated with it. But generally I agree…because ultimately if running side pipes vs full length exhaust hurt power then they would have found a work around. Ultimately the gases before the turbos and immediately after then leave the turbing housing is where most of the battle is fought

Ok, new diff, shafts, cradle, F&R shocks, hubs, arms, gearbox ...CHECK! Just need the dimensions for new alloy tailshaft and have a few big weekends of the car up inm the air losing her undercarriage and whilst its up in the air going to finally strip the sound deadening out of the boot and interior and spray the back half of the car and cage. Very excited to getting it back on the road and driving a car that is tight and free of rattles. I suppose after 14 years of loyal service she needs a good freshen up in the suspension and drivetrain.

Me? Somethintg custom that I built that probably wouldnt work anythign like I hoped or an off the shelf exhaust I have a twin setup planned for my car and just need to find the right price turbos so I can click "checkout" on my shopping cart of goodies for a twin setup. 4 mufflers and twin cats should hopefully mean I dont get booted off at track days

Definitely can be the case on NA cars. On turbo cars its not the point that too large an exhaust causes loss of back pressure. Its how you do the larger diam exhaust can increase back pressure. Off the turbo a small step change in diameter can be good at straightening the airflow for better flow in the exhaust. But generally sudden changes in diameter can add to back pressure. So if you go from a little 55mm opening in the turbone housing to a 3" pipe then the turbulence caused by the dramatic change can add to back pressure and poor cylinder evacuation. If I was doing a twin setup I would plann on doing twin 65mm off turbos and then nice pipe merges into 3.5-4.0" cat back and mufflers. (or twin 3" with 2.5" final mufflers)

I have tried a ~ 0.63 housing and a 0.86 housing on the same turbo and same engine. Made the same peak power but moved the curve a long way with far poorer response with the bigger housing. So if you are running E85 then go the smaller housing. If you are running pump the tune wont seem to handle the back pressure as well. If its a track car that is going to see sustained high revs and load then perhaps make sure you are not giving it a gob whack of boost when at the track like you can on the street. I am now running a T67 with a 10cm (~0.74) housing but once a few things are fixed on my car will be gong back to the 8cm housing (~0.63) Thats on a 2.5L 6cyl

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