:cat: Good morning everybody. Would somebody be kind enough to let me know what the difference between the low Pressure Turbo and the High Pressure Turbo. I believe my S80 2.0Litre is a Low Pressure Turbo. I don't really know what that means.

Any information would be appreciated thank you.

Cheers :)

I am still reading and learning about stuffs so, I hope someone corrects me if I am wrong.

The difference between the two is, obviously the pressure generated by the spinning turbos. While higher pressure will provide more boost, it doesn't necessarily mean more power (as in HPs).

If you look at the cars for instance, a stock LPT would carry a factory-fitted boost at about 0.4 to 0.5 bar, but a HPT could easily be double as that, say at about 0.8 to 0.9 bar.

Turbo boost developed by the high pressure turbo provides quick low engine rpm response while the low pressure turbo for the high engine rpm. Which may not be a coincidence why you see HPT cars go a lot faster.

Hi Aukland

I think you made a typo re the engine capacity of your S80. In Australia, I believe we have 2 models, the non -turbo and HPT. The HPT is badged T6 and has 2 turbos.

Ampangbear is right, the high pressure turbo merely means more boost. Whether Volvo uses a different turbo on the LPT and HPT, I am not sure. However, HPT has the boost pressures wound up.

I dynoed my T4 and it put out 15psi of boost which is phenomenal for a factory vehicle. This is a HPT model...

:cat: Hi there. Thank you for your replies. My S80 is definitely a two litre engine. All the documentation says so. If not, I am getting 8.0L per 100k's. If the engine is bigger-I must have the most economical unit ever produced!!

One of the problems I have with this car-is the fact I had a 740 Turbo with a gauge on the dash. I knew from the gauge when I was using the turbo. However, Volvo did not install such a gauge in the S80. Now I don't know when I am using the turbo or what speed I should be driving at to use it correctly.

This is one area I could use a bit of help please. Any info? Many thanks

Cheers and looking forward to hearing from anybody.

ipd sells a kit for the later cars. try ipdusa.com for more details.

For a cheaper option, especially since you're in NZ, you could try any good wireman to help you on this. You can buy the gauges (many brands now available!) yourself and ask him to fix it up for you...


:)

:cat: Good morning Ampangbear. I will check out the agent the next time I am there and also the local garages.

You hit the nail on the head with NZ bit. If you are not careful down here, you'll get exactly what you asked for. What you wouldn't realise until it was too late, that the whole thing would look like something the county council did for the water works in 1946!

Cheers :P

I dont think there is a wrong way to use a turbo. Generally, turbos kick in around 2500 rpm, give or take a coulpe hundred rpms. Depends on the size and design of the turbo, but get on it from a stop and watch the tach. Youll be able to feel the turbo kicking in. (dont do it in heavy traffic BTW)

The speed u are driving at is basically irrelevant. Its dependant on the rpms and throttle position -how mauch gas you're giving it.

http://en.wikipedia.org/wiki/Turbo
At the bottom is a link for "boost gauge"

Hope that helps some

:cat: Good afternoon S 60 R. Thank you for the information. Wiki provides a fairly full answer. I will spend the next couple of days reading it.

Thank you for your help.

Cheers :clap:

LPT = Low Pressure Turbo

HPT = High Pressure Turbo

The differences between them, LPT's are smaller turbos for example a 13g. A HPT is bigger for example a 15g/16T/18T/19T. Another difference is the amount of boost that they can hold and maintain effeciently and also how much boost is produced stock. LPT for example 5-7PSI, on the other hand a HPT puts out more like 10-15PSI.

As far as effecincy goes a LPT will loose effective effiency after 12PSI about possibly hold good boost till 15PSI. But then it looses its efficiency. On the other hand a HPT can hold 15PSI all day long and then a little more say up to 17PSI.

Also if you want to know how much boost your making get a BOOST/VACCUM gauge. Autometer makes great gauges.

Can you swap the LPT to a HPT without much modification? Will it help? Could you instantly boost to 15psi with a reprogram or is there more to it than that?

You would have to change to the corresponding fuel injectors and computer programming for the engine and the tranny. All plumbing should be straightforward as long as you got all the hardware from the donor vehicle. Hope that helps.