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They are a fair bit bigger but shouldnt be ridiculous on a rb20 id say this mod in conjuction with cam gears it should bring on full boost by around 3.2-3.8k....

If it a high flow they are generally good for around 220rwkw, and if it is a high flow dont worry about the turbos age just ask when it was high flowed cuase all the wearing items should have been replaced at the same time!!!

  • 2 months later...

wow.. 3300rpm.. Is that on the street say rolling on in second gear from low rpm or loaded up on the dyno.

My rb20det with the stock rb20det turbo rolling on in second used to see 15psi by around 3500rpm.

Loading it up I could see 15psi by 2800rpm or so.

A friend has a VLT, rolling on from low rpm in second saw 12-13psi around 3000rpm.

I've seen some real dodgy T3/T04 hybrids so make sure what you get is reasonably well thought out . The most I would ever do to the VL spec dinosaur T3 is go up to the last size ie 60 to 65 trim T3 compressor as its the turbine thats lacking and definatly not designed to power T4 comps .

Avoid eight bladed T04B compressors at all costs as they are low speed surging dogs . If you must use a "B" wheel use a six bladed one as they have some chance of working - kind of .

I doubt an RB20 will thank you for a bush bearing turbo , the oil and optional water fittings are all different as is the actuator waste gate and outlet pipe . The fiddly bits make it an expensive conversion .

It goes against the grain but something like a GT28RS in the RB25 exhaust housing will at least bolt up to everything on the hot side . Oil water and air plumbing are not std but what else is ? I'd be thinking about the std turbo with the RB25 exhaust housing or the complete unit if its on a cheap budget .

Cheers A .

I have a T3/T04 turbo on my RB20 with a exhaust housing identical to a VL and a TO4 compressor housing. Not sure if the wheels are similar or not.

As Disco said, if your upgrading, a bush bearing turbo is not the most ideal thing to replace it with but I guess it all depends on what your budget is and what you want from the car.

On my car, lets say second gear and rolling at low rpms and then mashing the throttle it will see about 16psi at approx. 3800rpm but I have a decent manifold thats been designed for this turbo.

The power delivery is very harsh. There is nothing linear at all about its delivery. The motor seems asleep and a split second later the boost gauge is peaking and the car is skating all over the road. If friends come for a drive they have a grin from ear to ear for an hour but living with it everyday is a real pain.

To answer your question if it could be called an upgrade? Personally I would say its a step backwards.

FATGTS-R that tends to be the real world experience .

The problem was heavy (for their size) turbines and oil shear drag from bush bearings with their excess contact area compared to ball bearings . Exhaust housings had to have smaller ARR's to overcome the drag and innertia and give a reasonal boost threshold . The problem is this then limits total gas flow creating thermal and detonation dramas (reversion/polution/charge heating) .

Modern turbos use low friction bearings and low innertia rotating group which require less exhaust eneregy to get them going .

Turbine housings have come along in leaps and bounds , the modern ones have less surface flow losses and the gas retains more enery by being ducted through wider nozzles . If you compare A T3 turbine to a GT BB turbine (eg GT30) the tip heights (the inducer where the gas is fed into the blades is quite high or wide) are much greater on the GT's . The earlier designs were trying to harness the exhaust energy from low or narrow tip height inducers and the exducer section tended to wrap around more than the GT's to gain a little more trapping efficiency . The narrow nozzle of the earlier types tended to speed up the gas flow more so and the partially avoidable restriction cost the turbine some energy and the housing some flow for its size .

Its easy to think that the old dinosaurs are easy and cheap - but if you were buying them brand new the price difference is often small compared to the newer ones once they're in place .

Cheers A .

  • 2 weeks later...
wow.. 3300rpm.. Is that on the street say rolling on in second gear from low rpm or loaded up on the dyno.

My rb20det with the stock rb20det turbo rolling on in second used to see 15psi by around 3500rpm.

Loading it up I could see 15psi by 2800rpm or so.

A friend has a VLT, rolling on from low rpm in second saw 12-13psi around 3000rpm.

nah dude thats in 4th gear, 2nd it doesn't come on till 4 grand roughly. you know you measure boost in 4th and 5th gear don't you, as its inconsistent in the lower gears

How often do you accelerate hard from low rpm in 4th. :O

You do however punch it hard from down low out of corners in second. Testing second gives more of an indication how the car drives under 'general' street conditions.

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