2871r

[Realutionist]

Where can i get a decent one from? And how does the 3071r compare? Looking for quick spooling turbo and 400+ bhp

 

[The Doc]

Get a 2863hta or a 2867hta if you want quicker spool, 2871 are not that good as a 3071 .63ar.

 

[whytie]

I've got a 2871r away getting rebuilt which I'm putting up for sale when it comes back.

Totally agree though, 3071r is the one to buy. It's just a better all round turbo and the extra torque you gain from it makes it such a better car.

 

[fubar andy]

What makes 2871's not that good?

 

[The Doc]

Compressor side is more effiecient than exhaust side and miss match of wheel size on a 2 litre engine means you get more backpressure on the exhaust side therefor less power and poorer transcient response which is lag, the point it comes on song is at best a few hundred rpm lower than a 3071 .63ar ..
So there is not alot of gain and more to be lost.

 

[fubar andy]

Could that be combated with a better flowing manifold or exhaust system?

 

[PobodY]

Compressor side is more effiecient than exhaust side and miss match of wheel size on a 2 litre engine

That makes sense to me.

Have I got this straight: - The compressor is too small for that turbine; that's why something like a 2863 works better.
If you go up to a "30" size compressor, then the exhaust side is a better match?

 

[Wes]

Sorry for the noob reply, but what does the .XXar measurement stand for when looking at turbos?
how does this figure affect how the turbo works?

 

[The Doc]

Could that be combated with a better flowing manifold or exhaust system?

Nope the restriction is the turbine size

 

[The Doc]

That makes sense to me.

Have I got this straight: - The compressor is too small for that turbine; that's why something like a 2863 works better.
If you go up to a "30" size compressor, then the exhaust side is a better match?

Nope the compressor is too big for the turbine size...so it will push more in the engine than can get out

 

[The Doc]

Sorry for the noob reply, but what does the .XXar measurement stand for when looking at turbos?
how does this figure affect how the turbo works?

.63ar is a measurement of the turbine housing..smaller means the turbo will come on boost as such earlier in the rev range but at the expence it will not flow as much exhsust gas and make as much power higher in the rev range as the engine will not breeth as well.

 

[fubar andy]

.63ar is a measurement of the turbine housing..smaller means the turbo will come on boost as such earlier in the rev range but at the expence it will not flow as much exhsust gas and make as much power higher in the rev range as the engine will not breeth as well.

So would a .86 housing somewhat help to alleviate the restriction?

 

[The Doc]

At the expence of the turbo coming on song higher up the rev range .