Turbo options - help!

[Chesney84]

Recently found a turbo of the following spec and seems suitable for a C1J, could any of you guys tell me whether or not this would work:

Large alloy compressor housing with 2in inlet flange and 2in outlet flange
56mm compressor wheel capable of up to 30lb/min
Oil cooled journal bearing core.
0.52 A/R quick spool turbine housing with T2 inlet flange and 3bolt outlet flange.
54mm GT25 high flow turbine wheel

One of the Garrett GT25 series, your thoughts would be appreciated. Seems a quicker/ cheaper way of achieving g boost and power than trying to re-engineer a T2?

[Ian S]

Sound completely incompatible.

I'm no expert but:

30lb/min?? What does that mean? Flow measured in litres / sec at a given PSI, I've heard of.

Oil cooled core!! Who wrote that! Oil lubricates, water cools. Water cooled core is what you what.

The 5GTT has possibly the hottest turbo in any engine bay. The 5GTT original non water cooled would burn the oil and jam the bearing and shaft. That happened to a water cooled T2 I had. Renault switched to water cooled, I presume, for longer term reliability.

50mm inlet? Aren't the T2, etc about 75mm inlet, ie, hose inner diameter?

0.52 turbine housing might be quite large and far from quick spool on a low compression 1.4 litre. The T2 is a 0.35. Normal T25 for the 5GTT seemed to be 0.49. And isn't the compressor is a big factor in how fast it make boost pressure?

As said already, the 'Tomcat' spec seemed to be a good one. I no longer know what that was though! Many, possibly all, the people who eventually worked their way up to a bigger turbo, would not go back to a smaller one, would put up with some lag in order to have the extra get up and go, especially at higher speeds / gas flows.

The VNT seemed to be able to give low lag and high gas flow.

There seemed to be a lot of newer, probably better, turbos since I last used my 5GTT 12 years ago.

[Chesney84]

Garrett GT2556 300bhp T2 flange turbo. Quick spool 0.52 turbine housing. GT25 https://rover.ebay.com/rover/0/0/0?m...2F332585219582

This is the link to it, should have just done that in the first place. It does look like it may be oil cooled as I can only see two fittings on it, so in hindsight as you say not really suitable. Was just a thought, thanks Ian!

[Chesney84]

And by 30lb/min I assumed he meant 30psi minimum?

[tubbyG]

Only having oil cooling a turbo is fine....

Plenty people have ran turbos without coolant going through it without issue. A good quality oil with regular changes will ensure it lasts.
On my vnt there is only oil for cooling, I have added in an oil cooler to aid in keeping temps reasonable.

[Chesney84]

I just saw it and seems reasonably priced, think it originally came from a company called Compressor Racing who try and source odd and rare turbo's that fulfil the same specs as some big name brands. I know most road car turbo's nowadays are water cooled, but many industrial and heavy plant turbo's are oil cooled, and this turbo came from a Perkins engine so explains why. I can see the exhaust housing has a different shaped inlet and a 3 bolt outlet and would require clocking and relocation of the wastegate assy. but none of those are majors really.

Do you run your oil outlet from the turbo straight into the feed to the oil cooler?

[Ian S]

Possibly another factor is the spin speed. The little T2 will be at a higher, or much higher, speed on a 5GTT (200,000 rpm?) compared to a VNT (which came from a lorry?), which will be quite big really and move more air per turn. (100,000, or 75,000?? I've forgotten :/ )

Normally industrial, lorry, etc, turbos are making lowish boost aren't they, and turning slower and not getting so hot? But the 5GTT, 10 or 12psi and the likelihood of being turned up to 15psi. Renault would only spend money on water cooling because they NEEDED to. These business cost to maybe the third decimal place and want to save every £0.001 they can.