Any Turbo Experts here

kluivert

Hi there,

Does anyone know anything about turbos

Meaning what is PSI, turbo timing etc - the only thing i know is a turbo lag. How do they work, interested in learning something about them.

I know the rest of the engine ok, turbos would be my weak area.

Is a turbo worth having or is it just an extra cost.

dcGT

Here's a good start:

http://auto.howstuffworks.com/turbo.htm

Similar info here...

http://www.toyotagtturbo.com/turbo/index.htm

PSI is a measure of pressure (boost in terms of turbos). BAR is another measure (used in Japan, among other countries). For example, an engine might run at 10 PSI or 1 BAR of boost.

Turbos are worth having, but it's not a case of just bolting one on to your Micra. There's an AWFUL lot of work involved in fitting them to a N/A engine (if at all possible). Therefore, people don't normally turbocharge N/A cars. Sometimes people uprate turbos on turboed cars, but even this involves a lot of work (uprated con-rods, forged pistons etc. to name but a few mods)

A turbo timer is a device that allows your engine to run for a set period after driving the car, so that the turbo has time to cool down (with oil circulating around it). Otherwise, the turbo's life is reduced as the oil bakes (due to the intense heat after driving the car/turbo hard) around the turbo's internals.

A very brief intro, but hope this helps,

DC.

kluivert

Cheers lad

I forgot about "Howstuffworks" its a great site to learn the basics.

All the turbo really does it condense air and push it thru into the pistons.

It was saying that sea level pressure is 14psi and a turbo will push 7-8psi about 50% minus 10% for running itself.

Therefore different cars would have different psi settings?

You would really need and it would worth spending the xtra cash on updating some engine parts as well.

dcGT

Yep, essentially, all a turbo does is compress air.
More air + more fuel = more power.

Many enthusiasts uprate turbos/engine components for a hobby. The 'how much can I squeeze out of this engine' scenario.

Depending on the engine and turbo size, yes, turbos can run at different boost levels.

Don't forget to look up other components, such as wastegates & intercoolers.

DC.

Gerry

Yeah, basically adding a turbo to a N/A engine is probably more trouble than its worth. You'd need to be a very experience mechanic, plus you'd end up changing a lot of engine parts.
Turbo lag - the turbo won't make any noticeable difference until the engine revs up a bit, it takes a little time to spin up. So this means you can be waiting a bit after you put your foot down. If you really want to drive a turbo car fast, you need to keep the revs up as much as possible
Of course turbo lag isn't as bad as it used to be, turbos are now quicker to spin up, and they have a few tricks for keeping them spinning at low revs now also ( variable nozzle turbos I think ).

Squirrel

Another way of reducing turbo lag is to fit more, smaller turbos, like the EB110

dcGT

The smaller the turbo, the less rotational forces are involved (rotational inertia).
Therefore, generally: -

Small turbo = quick spool-up time, but small boost
Big turbo = slow spool-up time, but big boost

The trick is finding a trade-off between the two.

DC.

ds20prefecture

Superchargers are generally considered easier to fit to a naturally aspirated engine, and also considered to be more progressive as they work (a little) at lower engine speeds. They do not seem to be the compressor of choice for very high power engines - no idea why.

There was a company in Scotland called Sprintex that fitted an Rootes-type supercharger to pretty much any car. Car magazine did a feature on a Supercharged 2CV in the early nineties - it was a real GTi frightener, until it burst into flames

You're still talking big money to convert a na engine, though. If you have a turbo car already, there are a number of specialists who will tune the car for reasonable money. e.g. Jabbasport in the UK will tune the Octavia vRS from 180 to about 230bhp for about £1000. Even better, they'll tune the 110bhp diesel to 160!

ando

dcGT wrote:

Big turbo = slow spool-up time, but big boost

a good example of that would be when Top Gear raced an Evo against a Fiat Stello and the Fiat won!

dcGT

ando wrote:

a good example of that would be when Top Gear raced an Evo against a Fiat Stello and the Fiat won!

Exactly.

DC.

iregk

Someone mentioned super chargers. The difference between super chargers and why they work at low rev and normal tubos is that its belt driven.

A normal turbo will sit and wait (lag) until the engine is running at a good speed and air pressure is good. Then it kicks in and all hell breaks loose. A super charger is a belt driven turbine so once the engine starts spinning the s/c starts spinning as well. The main reason why they haven't taken off as much is they are really only for acceleration. The super charged engines dont suffer turbo lag but they dont do too good at high pressure 5+ revs. This is where your super k spec turbo comes into play.

As for avoiding lag the mid 90's RZ Supra's were quite good. Twin turbo with butter fly valve. Small turbo that spins at 1.5k rev and dies off at 4, the butter fly valve kicks in and the larger turbo takes over and spins up to 7k.

iregk

Just to answer the original question also:
Meaning what is PSI, turbo timing etc - the only thing i know is a turbo lag. How do they work, interested in learning something about them.

PSI as someone put it is air pressure. The higher the pressure of the air and fuel condensed = more power. But also if your tuning to a good standard you've got to look at the injection as well. Maybe an injection with a higher bar pressure to go with a decent turbo would be worth it as well.

Turbo timing is a safety mechanism. Get a turbo timer and stick it on your dash. When a turbo spins it uses the oil from the engine. When you shut off the engine the engine stops but the turbo does not. It doesn't stop automatically it stops when its motion runs out. So you fly into your driveway turbo spinning and kill the engine, the engine stops and the oil sumps to the bottom (away from the turbo), the turbo is still spinning with no oil and can blow due to excissive heat. What the timer does is it tells you how long you have to go before killing the engine. So you stop your car just leave it idle to keep the oil flowing let the turbo slow down and then you can kill the engine.

"Is a turbo worth having or is it just an extra cost." - very much depends on the car. Micra/Punto not woth the hastle. Golf/Supra - Game on.