Question: 1 :Inline 5 pot 2.5tdi volvo v70...audi/vw engine 98 plated, as i understand it so far a turbo has to spin up to speed before it kicks in, is the ratio between turbine and compressor the same, 1/1 or is that a variable,2: could i have two turbos of different size on one pipe, a small one that kicks in at low revs and a bigger one to take over on the higher rev band???
Turbo help
- Thread starter johno406
- Start date
The compressor and turbine wheels are fixed to a shaft so 1-1 ratio.
Yes you can have 2 different size turbos BUT why would you want to add the complication when you can get an excellent result with a single turbo unless you are out to set or break records?
IIRC the turbine housing is cast with the manifold so you will need a custom / bespoke steam pipe manifold.
Yes you can have 2 different size turbos BUT why would you want to add the complication when you can get an excellent result with a single turbo unless you are out to set or break records?
IIRC the turbine housing is cast with the manifold so you will need a custom / bespoke steam pipe manifold.
Thanks for the advice, i could just bung a big turbo on, but i was looking at the time it takes to spool up, im just asking at the moment and learning, with lots of reading, but why not have a turbo on through the entire rev range? off the shelf is not me, fabrication and bespoke is 
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The vanes in modern turbos are so much better than stock turbos from 10 years ago. Look into hybrid turbos for the best of both worlds.
A modern large turbo can spool up from low rpm, the days of lots of lag are long gone, unless you get a turbo setup for very high power gains where it all happens at the top end.
I'd say that you need a twin scroll turbo, get the manifold right and you'll have a monster on your hands. Fuelling will probably need some tweaks but the engines are pretty solid and can take quite a bit of power.
A twin turbo setup is a nightmare to get right, most are connected in series with a boost controller that cuts in as the RPM changes. The second turbo will then compress further the charge from the first turbo.
A modern large turbo can spool up from low rpm, the days of lots of lag are long gone, unless you get a turbo setup for very high power gains where it all happens at the top end.
I'd say that you need a twin scroll turbo, get the manifold right and you'll have a monster on your hands. Fuelling will probably need some tweaks but the engines are pretty solid and can take quite a bit of power.
A twin turbo setup is a nightmare to get right, most are connected in series with a boost controller that cuts in as the RPM changes. The second turbo will then compress further the charge from the first turbo.
