Shortcut
Posted a lot
I won't be there when you cross the road, so always use the Green Cross Code.
Posts: 3,037
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Nov 13, 2004 19:46:20 GMT
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I know a few of you guys are quite knowledgable about these more technical matters so...
Is it hard to alter the point at which the turbo o your car kicks in. I'm guessing that it's pretty set byt he engine management and altering it requires major surgery. To get the boost to kick in at a lower rev would mean getting a smaller turbo fitted?
Cheers
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Last Edit: Nov 13, 2004 19:46:50 GMT by Shortcut
This space available to rent. Reach literally dozens of people. Cheap rates!
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turbo questionBenzBoy
@benzboy
Club Retro Rides Member 7
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Nov 13, 2004 19:54:18 GMT
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I'm not an expert by any means, but I've been looking into turbos for a while. Every turbo has different characteristics, and will "spool up" at different engine speeds. As a basic rule of thumb the smaller the blower, the quicker it'll spool (i.e.: at lower RPM) simply because it takes less energy to move a smaller turbine. Something I haven't gone into yet is turbo maps as it all looks scarily complicated, but by using the data you can select a turbo size and turbine trim that suits your application. I believe Mr Bo11ox is resident hexpert in all things turbo so he may be able to give a more detailed explanation. My philosophy is bolt it on and see! I've basically chosen very small turbochargers as the old V8 is quite low-revving, and I want to get more torque. However this is very un-scientific so I really don't know what the outcome will be until I eventually turn the key!
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Nov 13, 2004 20:19:02 GMT
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I wish I was an expert on turbo installations! I am not, however I can tell you that the 'spin-up threshold' is governed by the size of the turbine, and also by the A/R (x-section area/radius) ratio of the turbine. The A/R is kind of a way of 'fine tuning' the speed at which the turbo spins up. A bigger A/R gives more outright power, a smaller one will spool up quicker.
If you already have the turbo on your engine, you cant make it spin up any quicker without changing the size or geomerty of the turbo.
Incidentally, ask me again in 6 months! I'm applying for a new job as a development engineer! No more mucking about solving quality problems now, i'm gonna be surrounded by engine test beds and the like!!!! Woo-hoo!
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1972 Fiat 130 1985 Talbot Alpine 1974 Lancia Beta Saloon 1975 + 1986 Mazda 929 Koop + Wagon 1982 Fiat Argenta 2.0 iniezione elettronica 1977 Toyota Carina TA14 BEST CAR EVER!!!!!!!! 1979 Datsun B310 Sunny 4-dr 1984 Audi 200 Quattro Turbo 1983 Honda Accord 1.6 DX GONE1989 Alfa 75 2.0 TS Mr T says: TREAT YO MOTHER RIGHT!
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Nov 13, 2004 20:19:25 GMT
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There are other factors that affect the rate at which the turbo spins up to speed. How well the intake flows is one of them. When I was running my Bluebird turbo, I swapped the originall intake manifold for one off a 2.0L Bluebird which has a bigger plenum and much longer runners. At the same time I swapped the 45mm throttle body for a 55mm one. The result was the turbo hit full boost 1000rpm lower than it did before.
With turbo sizing, everything is a bit of a trade off. The stock BB turbo engine uses a tiny T2 despite being a 1.8. This means it has great low end grunt and lot of mid range but runs out of puff beyond 6000rpm. Swapping to a larger T25 for example will give more power and definately more higher up but at the expense of low rpm response and torque.
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1962 Datsun Bluebird Estate - 1971 Datsun 510 SSS - 1976 Datsun 710 SSS - 1981 Dodge van - 1985 Nissan Cherry Europe GTi - 1988 Nissan Prairie - 1990 Hyundai Pony Pickup - 1992 Mazda MX5
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Nov 13, 2004 20:25:40 GMT
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You could get a hybrid turbo which gives you the best of both worlds.
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turbo questionBenzBoy
@benzboy
Club Retro Rides Member 7
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Nov 13, 2004 21:19:54 GMT
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There seems to be a lot of hybrid turbos about - to be honest I haven't really delved into that either as I already have far too much to think about! My blowers are from a diesel (gasp!) to which armchair enthusiasts have said "it just won't work" - when asked why they don't have the answers. As Mr_Bo11ox explained to me in another thread the compressor turbine housing isn't as resilient to heat, and I've since found out that they don't have positive spindle seals. However this just means that if the turbine is subjected to vacuum (i.e.: in a draw-thru setup where the carb butterfly is before the turbine) it'll draw oil into the intake. For me this isn't a problem, and I'll just try to keep the blowers as cool as possible with plenty of ducting. If they destroy themselves they were only a few quid each so I'll just junk them!! Are you thinking of going turbocharged, 104ZS?
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GrumpyOldMan
Part of things
Addicted to unreliable cars ?!
Posts: 182
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Nov 14, 2004 13:02:24 GMT
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Apart from the turbocharger and the intake, the following are also important : camshaft design and timing, static compression ratio, ignition timing.
The easiest way is indeed to choose a smaller turbo or a 'hybrid' with a smaller exhaust 'part' (unfortunately I don't know the correct term in English).
The hardest way is to do what Nissan did with the Micra Turbos... Use both a supercharger and a turbocharger !
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