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Tuning turbo time!

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Tuning turbo time!

fingers99 said:
Generally, water cooled ones have ball bearings, so will spool up quicker.
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erm... no. Ive seen countless journal bearing watercooled turbos, and it was a safe bet (certainty actually) that craigk's turbo is journal bearing.

You're right though, I wouldnt run a BB turbo without water either :eek:

Craig - BB cores DO help lag a little - you notice it a bit changing from a gt28 to a gt28r (exactly same turbo sizes and wheels, just BB core)

But more efficient turbine/compressor wheels and housings play more of a part in reducing lag like you say - eg a few of the nissan lads say that the newer holsets (journal) spool faster than their BB garrett equivelents... go figure...
 
Munkul said:
Craig - BB cores DO help lag a little - you notice it a bit changing from a gt28 to a gt28r (exactly same turbo sizes and wheels, just BB core)
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mad I wouldnt of expected it to be noticeable... but yes i bet 99% of lag is due to inertia and efficenty of the wheels.

ever compared a old garret to a new GT one???
the old turbine has very thick fins (obviously because the metal technology back then would no allow for thin blades to not melt away under the heat. ) and heavy.

the difference in lag between them is night and day!

I reckon the next major step up for a petrol turbo will be a VVT... they are working brilliant on diesels (practically used on every diesel turbo now) but wont take the heat of a petrol engine.
 
Porsche have been running variable vain turbo's on the 911 for a number of years now, that's why it's such a tractable yet free revving car.

I believe the technology was invented by Holset which is part of Cummins.

BB turbos do reduce lag by decreasing spool up time. Many integrale/Fiat Coupe/Nissan 200SX owners change from older T2.5/3's to newer GT28R because it makes the car much better responding at low revs without loss of higher end power.
 
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One clue is in Garret's recommendations for turbos vis a vis engine capacity. The R ones (the ball bearing ones) have a much larger capacity range.

Personally, if the manufacturer intended a turbo to be water cooled, I'd do a bit of plumbing.

There are turbos out there with titanium/stellite internals, water cooling and ball bearings and dual entry. That'd be what to go for given the opportunity: all seems to be JDM spec, though.
 
fingers99 said:
Personally, if the manufacturer intended a turbo to be water cooled, I'd do a bit of plumbing.

There are turbos out there with titanium/stellite internals, water cooling and ball bearings and dual entry. That'd be what to go for given the opportunity: all seems to be JDM spec, though.
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I REALLY doubt the centos cooling system would cope with a watercooled turbo! even more so when you consider its also trying to keep up with a engine with over twice the power the cooling system was designed for.
then you have the fact there is simply no room for the extra pipe work around the turbo!

my turbo is used widely by the mini guys with aircooled cores and they have no problems at all.

I dont think anyone with a cento is ever going to be fitting a exotic internal/ball bearing/dual entry turbo (infact i bet you cant get an exotic turbo small enough for a cento)

and if i was paying over a grand for a turbo then id install a cooling system just for the turbo lol
 
progress...

welded the two inner tubes. sorta... the welder went all pissy on me with the gas not coming out the nozzle! took it apart about 4 times before stripping the whole thing to find the liner has pushed itself to the end of the gun and started to melt blocking gas flow (n)

getting there though!
 

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craigb244 said:
progress...

welded the two inner tubes. sorta... the welder went all pissy on me with the gas not coming out the nozzle! took it apart about 4 times before stripping the whole thing to find the liner has pushed itself to the end of the gun and started to melt blocking gas flow (n)

getting there though!
Click to expand...

lovly work i have to say :)

and rome wasnt built in a day
 
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craigb244 said:
I REALLY doubt the centos cooling system would cope with a watercooled turbo! even more so when you consider its also trying to keep up with a engine with over twice the power the cooling system was designed for.
then you have the fact there is simply no room for the extra pipe work around the turbo!
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I beg to differ ;) It does cope, provided you have everything else sorted out (good condition radiator, oil cooler, cooler thermostat). Only problem I get is a bit more than usual heating in still traffic, but this is mostly due to turbo sitting next to the radiator, not the power output of the engine. On the run I actually get cooler water temps than I used to have in an unmodded 1.1SPI. Re the pipework, well, you have to be a bloody surgeon, but it is doable.

Anyhow, I run my turbo water cooled since X-mas and everything is well so far (y)
 
I will, if I can find one! There's a JDM one for a Scooby Legend ( 1 of 2) which is said to spool up super quick (ball bearing and Ti internals). Failing that, I might just fit a GT25R.

But think about what you're saying. The excess heat has to go to oil or water (and hence to air). To my mind it really doesn't matter (given adequate radiators, etc.) which path it takes. In a water cooled engine without an oil cooler, all the heat from the oil (except a tiny bit lost via the sump) will go to the water. Even in an engine with an oil cooler, a substantial portion goes to the water (heat can only go from cold to hot, never the other way round, and the oil is generally a lot hotter than the water).

People don't usually fit hugely bigger radiators when changing from one to the other.
 
fingers99 said:
I will, if I can find one! There's a JDM one for a Scooby Legend ( 1 of 2) which is said to spool up super quick (ball bearing and Ti internals). Failing that, I might just fit a GT25R.
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but... why? it would wreck the engine's driveability. Even the 1.4 GT owners complain of lots of lag with the gt25, and ball bearings dont just magic away all the lag and high threshold you'd get with the 1.2!!!

If you have to have 250bhp on a FIRE, then by all means, "fire" away (sorry) but you'd be MUCH better off getting a GT17 hybrid and sticking with around 200bhp, which will be much more usable power!
 
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exactly. you could fit a gt25 but it will make a car for pub talk.

it "could" make more power but will all be in a big bunch (which removes the whole point of a turbo car)
what use is a car that has tons of power and stupid amount of money spent when it has peak power at 6000(if your lucky)rpm and rev limit at 7000?

Im trying to make my car as usable as possible (because its actually used for motorsport)
hence why im going 16valve.... the only real way to make more power out of my 8valve is to fit a bigger turbo... but bigger means more lag and a less useful engine.
the 16valve will flow more and "should" allow a bigger turbo with less lag and much lower boost levels for the same power output (and so be more efficent/reliable)

not the best for pub talk!
 
According to Garret, a 1.4 will run a GT25R. Might ideally need a smaller impeller, BWTH. I think have ideas on how to put 200bhp down effectively, but it depresses me how little thought/attention is being devoted to that.

Very much a series of ideas on the backburner for me: priortity is to finish the chassis repairs on the car that will be ToyFIAT.
 
run....yes...be any good? highly doubt it.

ive put plenty of thought into getting power down/handling. but there really is not much you can do short of rear wheel drive (may as well just by a better car) any then its not even a cento anymore.

think my cento is a good as it gets without excessive work... atb/coil overs(setup to trofoe hillclimb/road rally specs)/rear arb/short rack/pas and the handling of it is amazing compared to a standard cento
 
Principle issue methinks is torque steer -- I think the VW folk are using anti rise front ends to combat that -- you could do a crude version by raising the rear end/lowering the front on the coil overs, but it'd be very crude.

15" wheels effectively raise the gearing, counter the torque a little.

1 degree front static negative is good for turn in. A way of reducing excessive rear negative camber would be handy.

Propper blade type ARBs both ends are always useful.

Big, soft tyres help. Putting down 200+ bhp isn't a real problem with FWD and slicks.

ToyFIAT bitterly resents your suggestion that she won't be a FIAT anymore. ;)
 
i think 15 will be worse for handling... im actually thinking of getting uno discs so i can go to 13inch wheels for sprinting. there are much better tyres available

15s will require very low profile tyres... which are crap and i bet you wont have much choice.

blade arb... pointless. might as well spend time getting normal ones set up well rather then getting a blade type to work which requires lots of time/effort/money and most likely never work well enough to be of any use.

there has to be a cut of point to everything... after a point its much better to just get something more suited to the task.
you wont gain anything from making a proper blade arb (doubt it will ever be "proper") for a car that will be just used to mess about on the road or a few track days.
 
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If we all treated our cento's like touring/ hot hatch racer then we would all probably have race licenses aswell as frequent passes to track days.

Point is non of us do, because we don't have an unlimited wallet. These cars will at best only be used for sprint racing, tracks days, or autocourse events.

All this work i'm doing to chalky I haven't put any forged internals in because at that point the engine becomes more valuable than the car itself, and for what? 5-10-15bhp gain? Not worth it.

The standard internals are fine, and will survive up to the job, the chassis itself is fine with a good old session with a welder and some tasty 25mm stitches.

At the end of the day the car can only be as good as what you can afford.

Getting back on topic, craig get some pictures up (y).

Thanks

X
 
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