Alex,ithink u should go for the maping session,which it needs it any way,and then decide

 

I'd think a well specced GT28 would be a very good compromise.

 

Has development of the VATN / variable nozzle turbochargers for petrol engines been given up by manufacturers ?

Biggest reason I sold my Sapphire was the awful low speed torque, it would be nice if a turbo could make good boost low down and still pull at high revs!

Edit to add dyno graph



Is this unusually crap ▲ ?

Turbo was a T3 with bigger compresor wheel, car had a big Pace intercooler, light green injectors magnex exhaust along with an unkown chip.

Mark

 

that wont happen,i have a lot of experience of the hx35 (specifically the 7 blade 12cm rear housing variety) on 2 litre 16v turbos and you will NEVER be spooling that in the range you are looking for,it will push 600bhp if required,its not going to spool like a .48 t3! id say full boost 4-4.5k rpm on one of those from experience.

 

For an engine making only 300bhp, it does seem laggy.

Really with a modern unit, there is little reason a sub 300bhp car cant be making full boost by 3000rpm.

You certainly wont find many original Jap engines/turbos pushing 280-300bhp hanging around until 4000rpm before they go.
Engines may play a part...but not that much.

 

no, they are in 'mass' production

 

I think some of the new 911's use VTN ?

 

t34-48 housing ?

 

Are they not robust enough for tuned engines ?

Mark

 

wasnt that sierra v6 from turbo technics with dual vnt's?

 

it would be, but i have to keep the t25 due to originality, looking at pos different exhaust housings or similar, we will see what stu at msd says when i take my car down for some work and a chat

 

why does a 'tuned' engine need a more 'robust' turbo than an OE engine with warranty? they just need to be the right size don't they?

 

the 28rs disco potato will be nice,had in my 1.6 and was pulling like a taxi.

 

Thanks for the info guys.

Before I change turbos I have decided to get it remapped to see what improvment can be made on the current set-up.

In addition to the .48 housing in the garage, Ive also got a 4wd exhaust manifold that could replace the current 2wd manifold thats on the car at present.

 

No idea

Perhaps the VATN turbochargers don't last at high boost levels ?

Does the EGT go up with boost ?

Mark

 

I think that's a sound plan.

 

Sounds like a plan !