How to confirm Turbo Efficiencty

[machine]

Friends,

I have 13BT motor placed in my bj61, but i am not satisfied by its performance as far as its pickup and torque is concerned. it picks up thrust while after about half of the throttle is pressed.

Can anybody let me know that how i may confirm that its turbo is working well or either its working or not .

thanks

[raohamid]

Most Turbos start functioning around 1800 - 2000 rpm, when does your start?

Rao.

[machine]

@Rao

bro, there is no turbo light in the dash as its converted from 3b to 13bt. BTW how would we know that now turbo is start and its working without its indicating light.

[whisky]

You should feel the push and probably hear it spool. If possible, disconnect the pipe from the manifold and see when your turbo builds full boost. Or better yet connect a boost gauge. You may also inspect the turbo by taking it off if you suspect it's in bad shape or is smoking. Bad turbos have leakage, broken fins and shaft play.

[SuhaibKiani]

Well the thing is that there are two things which determine the extra power on the turbo - the turbo itself and the boost compensator on the fuel pump.

A typical boost compensator looks and works something like this:(pic below)....more on this later.

As far as the turbo is concerned, in all likelihood it will be working but the critical thing is to find out how much boost is it giving you. For that as mentioned you need a boost guage. Sounds fancy? It isn't, go to any AC parts or piping shop/market and get a chinese pressure guage for PKR 165/- (some sell it for PKR 15 more but negotiate it down :)) along with a connector that allows you to connect a small air pipe onto it. Buy about 4 ft of thin rubber pipe (the type that connects the boost compensator to the turbo) along with it and connect one end to the guage and the other to the pipe that hooks to the top of the boost compensator via a small T joint (you'll have to get that too). All in all cost should be under PKR 400 and you may even slip PKR 100 to your chotta mechanic who can help you with the job!

Also check if there are any visible signs of the turbo leaking oil which would mean its leaking oil :)....

[SuhaibKiani]

Didn't realise the pic titles were in french and hopefully I am not speaking greek but just get that guage installed it should be simpler than it sounds....

[machine]

thanks SK - that seems simple. Please let me know that how much PSI is OK on that pressure meter and is there any standard throttle to pressure ratio :))

[aisheikh]

Open the turbo pipe going in the manifold. If there is oil in it then your turbo seals are leaked, if that is the case you must also have oil reduction in engine. Solution: Replace the Turbo :-p

If your tubo is in reasonable condition then following improvements can be done:
- Reduce the intake restriction into the turbo by installing a high-flow air intake.
- Reduce the exhaust restriction by installing a free-flow down-pipe and muffler
- Increase the turbo boost by installing a bleed value (or manual boost controller) to the wastegage actuator
- Play around with the boost compensator to optimize the boost / fuel ratio

Most of all as SuhaibKiani proposed, install a boost gauge to check your turbo performance.

[SuhaibKiani]

Actually we should also do the basics

1. Did you mean to say that turbo only engages after a lag when you press the accelerator half way?
   >Some lag is normal and you can play with the boost compensator settings to possibly reduce it....

2. Do you hear the turbo whistle on full acceleration?
   >loudness varies but essentially no whistle=no turbo. Also if the pipe going to your boost compensator is disconnected (or blocked) you can lose the kick of the turbo...

3. Who converted your engine and when?

4. I would think that the factory pressure should be 8-12 psi for the 13BT (you should check the net) but I am pretty sure the rugged B series should withstand upto 16-18psi of max boost as long as you have the cooling system down.
   >I believe these numbers are max boost and your pressure guage will show a build-up to the max number upon acceleration on a moving car starting from zero at around 1500-1800 rpm. Revving stationary car will only give you 1-2 psi max reading.

[last_look]

you would hear a whistle sound thats when the turbo is on

[sherwan_88]

B series engines have journal bearing turbo's which spool up very late. They merely add 20 to 30% more power to the engines original power so there is no real power just a lot of heat under the hood.

SK,
I believe whether moving or stationary the engine should produce the same amount of boost.

The reason i say this a moving car with a snorkel on a NA engine has a small factor of forced induction, a NA engine without a snokel has no forced induction. When a turbo is hooked up it uses exhaust gases to spin the turbine. From your post i interpret a staionary engine will produce less exhaust and a moving engine will produce more?

I believe that is not the case, turbo's use exhaust to propel the turbine and the turbine is connected to shaft and the shaft is connected to the compressor. So the speed of the turbine is parallel to the speed of compressor. So lets say we have a turbine and compressor of exactly the same size (most turbo's don't), so this equates to that the amount of exhaust going into the compressor is parallel to the amount of air the compressor is pushing in.

Now when a stationary turbo engine is revving at 2000 revs and is sucking in 70 liters of air per minute, a engine on the move will be sucking 70 liters of air per minute too.

Rotary pumps have mechanical governors opposed to inline one's which have vacuum ones. So you have a boost compensator which operates via pressure for a rotary pump. So when you have a surge from 5 psi to 10 psi the boost compensator will allow more fuel. There is no external factor here which involves more air being pushed into the engine when a engine is moving unless you have a mighty big snorkel and if you do manage to create a vacuum while running a turbo you will have some real serious issues with a engine.

I am a bit rusty on explaining things, but i think you get the idea what i am trying to say here. Maybe you can share your views on this, because i simply cannot understand how a stationary engine will suck in less air than a moving one.

I've had the experience of seeing small diesel turbo gensets running upto 18psi.

And this is not an attack.

[SuhaibKiani]

B series engines have journal bearing turbo's which spool up very late. They merely add 20 to 30% more power to the engines original power so there is no real power just a lot of heat under the hood.

SK,
I believe whether moving or stationary the engine should produce the same amount of boost.

The reason i say this a moving car with a snorkel on a NA engine has a small factor of forced induction, a NA engine without a snokel has no forced induction. When a turbo is hooked up it uses exhaust gases to spin the turbine. From your post i interpret a staionary engine will produce less exhaust and a moving engine will produce more?

I believe that is not the case, turbo's use exhaust to propel the turbine and the turbine is connected to shaft and the shaft is connected to the compressor. So the speed of the turbine is parallel to the speed of compressor. So lets say we have a turbine and compressor of exactly the same size (most turbo's don't), so this equates to that the amount of exhaust going into the compressor is parallel to the amount of air the compressor is pushing in.

Now when a stationary turbo engine is revving at 2000 revs and is sucking in 70 liters of air per minute, a engine on the move will be sucking 70 liters of air per minute too.

Rotary pumps have mechanical governors opposed to inline one's which have vacuum ones. So you have a boost compensator which operates via pressure for a rotary pump. So when you have a surge from 5 psi to 10 psi the boost compensator will allow more fuel. There is no external factor here which involves more air being pushed into the engine when a engine is moving unless you have a mighty big snorkel and if you do manage to create a vacuum while running a turbo you will have some real serious issues with a engine.

I am a bit rusty on explaining things, but i think you get the idea what i am trying to say here. Maybe you can share your views on this, because i simply cannot understand how a stationary engine will suck in less air than a moving one.

I've had the experience of seeing small diesel turbo gensets running upto 18psi.

And this is not an attack.

....no issues on attack/defence, I have just about zero real tech knowledge and always welcome feedback and corrections

I think we are on the same page here.... but just to be sure I mean if I rev my jeep in neutral it only shows 1-2psi at max throttle upto 3500rpm. If its in 1st/2nd gear it can get upto 15-18psi. I understand that this phenomenon is pretty normal and thats why any videos on the net re boost would be seen measuring it on a moving car....

I understand what you are saying that a stationery vs moving vehicle should produce the same result on the boost guage (thats what I would have thought too), but in reality there is a huge difference and I don't know why that is, maybe someone else can explain.....maybe I am missing something....

[aisheikh]

Turbo boost is based on the flow and temperature of exhaust gas. At idle you can rev up the engine and increase the exhaust flow, but then there is no load on the engine, hence no increase in exhaust gas temprature. While the vehicle is moving and especially on load (uphill, trailer pull, off-roading, accelerating) you will notice turbo boost.

[aisheikh]

One more thing to add.
Turbo boost is useless without the increase in fuel flow, as increased forced air in the engine requires more fuel to burn along with it to achieve real gain in power, that is why you need a boost compensator.
In naturally aspirated engine the fuel flow is propotional to the engine rpm. Howerver, in turbo charged engines the fuel flow is based on the engine rpm and turbo boost pressure.

[sherwan_88]

SK,
With some reasearch done, i have found out that a turbo only spools up
under load. I believe i was wrong on that part.

Technically if you look at it, the amount exhaust and EGT's are directly proportional to the amount of fuel injected. Air does not burn it only helps the fuel ignite and oxidize. So the engine should produce the same result in any situation.

I think i have to do some more research. :$

[Charged]

I think the subject of this thread is incorrect.. Turbo effieciency is measured differently.

There are many factors that affect spool up range. Efficiency of a turbo is is measured by its A/R (area radius) ratio. A/R ration is generally written on most aftermarket turbos and some oem turbos.

Its the ratio of exhaust output (turbine or hot side) area versus the distance from center of the turbine impeller to the center of the cross sectional area. The lesser the ratio the faster spool up you get. Thats why many people make hybrid turbos. They use the hot (turbine) side of one turbo and cold (compressor) side of another to achieve desired results.

Full spool up is always measured while driving since the reason for spool up is not entirely the flow of exhaust gases. Flow of gases is only a part of it, most of the spool up is done by rapid expansion of exhaust gases. And gases only expand radipdly when the engine is under load thats why you don't see full spool when a vehicle is being revved when parked.

I hope this help!

[SuhaibKiani]

I think the subject of this thread is incorrect.. Turbo effieciency is measured differently.

There are many factors that affect spool up range. Efficiency of a turbo is is measured by its A/R (area radius) ratio. A/R ration is generally written on most aftermarket turbos and some oem turbos.

Its the ratio of exhaust output (turbine or hot side) area versus the distance from center of the turbine impeller to the center of the cross sectional area. The lesser the ratio the faster spool up you get. Thats why many people make hybrid turbos. They use the hot (turbine) side of one turbo and cold (compressor) side of another to achieve desired results.

Full spool up is always measured while driving since the reason for spool up is not entirely the flow of exhaust gases. Flow of gases is only a part of it, most of the spool up is done by rapid expansion of exhaust gases. And gases only expand radipdly when the engine is under load thats why you don't see full spool when a vehicle is being revved when parked.

I hope this help!

@Charged: Many thanks for that, i think it clarifies the issues and some more.... as always, I continue to learn something new from you everytime!

@Sherwan: Good Stuff! Always good to see that some people still believe in research around here and are brave enough to correct their approach if needed!

Though I think we have moved away from the specific topic (if we ever were on it :)) but this is really good turbo-tech 101...........I wanted to ask about the maps/graphs for specific turbos and how they relate to the A/R ratio i.e. if they do at all :). I think the following one is for a T3-60 turbo:

[aali-01]

can i fit turbo in cuore ?

[060276]

very informative thread...keep it up guys..

[sherwan_88]

Here is very informative information made avaialbe by Garrett.

Basic:
TurboByGarrett.com - Turbo Tech101

Advanced:
TurboByGarrett.com - Turbo Tech102

Expert:
TurboByGarrett.com - Turbo Tech103

Diesel Tech:
http://www.turbobygarrett.com/turbobygarrett/tech_center/diesel_tech.html