55 replies to this topic

[Winstar]

Trucast, small world indeed Ours is simpler in terms of the movement of the component which is what makes it more durable, however the force needed to move the nozzel is alot greater and you need more expensive materials to cope with the wear in the actuation mechanism. The reason Holset, now Cummins Turbo Tech. went with the sliding vane was as the swing vane mechanism wasn't durable enough for heavy duty applications, we also have patents to stop others using a similar mechanism. However the swing vane can be produced cheaply and need less force therefore smaller actuator and package, but to get durability is hard due to the number of moving parts. In terms of performance there's not much in it, although swing vane is more efficient at low flow/closed down conditions and sliding vane better a high flow capacity as we can go 'over' open by having cut outs in the vanes allowing extra flow. Most of the Garrett/Borg VGT's are for deisel applications so have the same combustion temps of around 700 Deg C, the wear issue becomes more of a problem the hotter you get and Petrol combustion is around 900 Deg C. The other reason not many petrol cars use them is because unless your doing somthing fancy like late inlet valve closing for emissions you don't need a very high boost. For example we are now being asked for over 4 bar outlet pressure for our deisel applications.

[speedster]

Rob

I work at Trucast and supply Holset with the turbine wheel! Small world ehh!

In my limited experience the design of the Holset (Cummins) VG seems much simpler (cheaper??) than the BorgWarner/ Honeywell design. How do the two differing designs compare in terms of performance? Is the design difference due to the exhaust temperature differences?

Mike

The BorgWarner system appears to be using special areospace materials in it's construction. It must be a design specific for Porsche's requirements (else BW would let their distributors sell it, no?) If anybody could get the specs and a compressor map on the unit too that be great!

Edited by speedster, 03 January 2007 - 11:42 PM.

[paulf-cam]

The BorgWarner system appears to be using special areospace materials in it's construction. It must be a design specific for Porsche's requirements (else BW would let their distributors sell it, no?) If anybody could get the specs and a compressor map on the unit too that be great!

The compressor map would be 3d, wouldn't it for a VGT turbo? Sounds like fun trying to read that!

[RWinstanley]

The BorgWarner system appears to be using special areospace materials in it's construction. It must be a design specific for Porsche's requirements (else BW would let their distributors sell it, no?) If anybody could get the specs and a compressor map on the unit too that be great!

The compressor map would be 3d, wouldn't it for a VGT turbo? Sounds like fun trying to read that!

No the compressor stage is the same as a fixed geo turbine, as that would be a VGC

The turbine map however does change with the position so is mapped as 2d maps at steps through the range of movement, this can then be represented in 3d (but nobody can be arsed writing the software). These maps are then use in engine simulations such as GT power that interpolated between the maps at a give %open.

However there are simplified method of looking at the results.

[Winstar]

After a chat with a few people at work I found this, clicky, the only other petrol VGT application.

Which as it's originally for a 2.3 engine is more likely to have a compressor stage that will match the engine breathing of the VX 2.2 engine.

We're not sure who makes the turbo, but the best guess is IHI.

[johnaachen]

I work for Ricardo and we developed a demonstrator vehicle called LBGDI (Lean Boost Gasoline Direction Injection). The car was a Ford Focus and we used a 1.1litre 3 cylinder engine, running lean with a VGT. We were able to use a diesel VGT for this application since the exhaust temperatures were lower.

Have a look here if you are interested in knowing more....thats me BTW driving the car!

http://www.ricardo.c...i_rqarticle.pdf

[Winstar]

After a chat with a few people at work I found this, clicky, the only other petrol VGT application.

Which as it's originally for a 2.3 engine is more likely to have a compressor stage that will match the engine breathing of the VX 2.2 engine.

We're not sure who makes the turbo, but the best guess is IHI.

on further investigation it looks like this uses an actuated waste gate to change the flow through the turbo, not a vgt.

The one i was thinking of was the Mitsi.

Edited by Winstar, 04 January 2007 - 08:44 PM.

[speedster]

I work for Ricardo and we developed a demonstrator vehicle called LBGDI (Lean Boost Gasoline Direction Injection). The car was a Ford Focus and we used a 1.1litre 3 cylinder engine, running lean with a VGT. We were able to use a diesel VGT for this application since the exhaust temperatures were lower.

Have a look here if you are interested in knowing more....thats me BTW driving the car!

http://www.ricardo.c...i_rqarticle.pdf

Interesting... Do you know how the VGT was managed? I assume you had to acquire a specialised engine management system.

on further investigation it looks like this uses an actuated waste gate to change the flow through the turbo, not a vgt.

The one i was thinking of was the Mitsi.

Found this on ebay

CLICKY

[Winstar]

Is that turbo a VG? the mechanism looks more like a wastgate than a VG mechanism as it's got a simple actuator. But if it is MHI (Mitsubishi Heavey Industries) Turbo, I'll try to look up the model TD05H-16G-7 as we have a partnership with MHI. Although TD05 sounds big as we use TD04's on 4L deisel engines.

[johnaachen]

[quote name='speedster' date='Jan 4 2007, 22:40 ' post='540324']
[quote name='johnaachen' post='540263' date='Jan 4 2007, 20:27 ']
I work for Ricardo and we developed a demonstrator vehicle called LBGDI (Lean Boost Gasoline Direction Injection). The car was a Ford Focus and we used a 1.1litre 3 cylinder engine, running lean with a VGT. We were able to use a diesel VGT for this application since the exhaust temperatures were lower.

Have a look here if you are interested in knowing more....thats me BTW driving the car!

http://www.ricardo.c...i_rqarticle.pdf
[/quote]

Interesting... Do you know how the VGT was managed? I assume you had to acquire a specialised engine management system.

I dont think that I am allowed to say who supplied the ECU. The strategy was written by ourselves, well partly me actually and involved some addtional hardware used to bypass software in ECU. We wrote our own strategy using Ascet-SD and this was running on an ES1000 - mean anything to you? The lambda control strategy was also bypassed on the ECU and we wrote our own strategy again.

The VGT was driven using CAN via a REA smart actuator. Garrett VGT.

HTH

Who do you work for then?!

[speedster]

I dont think that I am allowed to say who supplied the ECU. The strategy was written by ourselves, well partly me actually and involved some addtional hardware used to bypass software in ECU. We wrote our own strategy using Ascet-SD and this was running on an ES1000 - mean anything to you? The lambda control strategy was also bypassed on the ECU and we wrote our own strategy again.

The VGT was driven using CAN via a REA smart actuator. Garrett VGT.

HTH

Who do you work for then?!

I take it that's the prototyping tool from ETAS? I can across it when I was looking for a standalone ETB driver but it's way out of my league.

Me, I don't work in the auto industry. I am just looking into this for my own engine design.

Did you just run this prototype on petrol?

[johnaachen]

Yeah its from ETAS and Ascet-SD is the language which the SW in which the code was written....which is a bit like a grown up version of Simulink. We only ran the vehicle on gasoline yes. This technology was really well received by all the companies we demonstrated it to but has yet to really take off..... What is an ETB driver? If you are going to do something like this yourself its not going to be cheap! You would need an engine on a test bed to do the development and calibration, plenty of spares for when you overboost the engine..... If you want any more information on the VGT I could try and get you it.....the VGT itself was off the shelf as far as I can remember....all you have to do is write the SW...which you will also need to be able to bypass the lambda controller in the ECU for....mate....I wouldnt want to have to do this!

[speedster]

ETB - Electronic Throttle Body... Software ain't a problem, that's my field of study! Can you get me your test rig sensor input figures with matching VGT behaviours (including boost vaules). What AFR were you running lean at? I'm interested in bioethanol however I've been told to expect a 30% increase in consumption when boosting for big power....

[johnaachen]

ETB - Electronic Throttle Body...

Software ain't a problem, that's my field of study!

Can you get me your test rig sensor input figures with matching VGT behaviours (including boost vaules).

What AFR were you running lean at? I'm interested in bioethanol however I've been told to expect a 30% increase in consumption when boosting for big power....

I couldn't give you any test bed data I am afraid -it would be client confidential. I know that we ran up to lambda=1.4. When boosting you need to hose in more fuel to cool down the turbo....well that was my understanding of it anyway:-)

[Winstar]

Right I've had a look at the product data for MHI and TD05 refers to the size of the turbine wheel, altough we only take upto TD04 before we use our product so I'm not sure of the size. 16G refers to the compressor size and i think it's about a 56mm wheel (thorney new uprated turbo uses a 52mm IIRC) although MHI Nomenclature isn't very clear so could be bigger. The G refers to it being a hi pressure type. 7 is the critical area of the turbine housing. So I can't see anything that would indicate it's a vg and I didn't think they did one below TD06, althoght the small(!!) stuff isn't my area. You may be able to get away with using a VG from a diesel for your application anyway as on a vehical the turbo is only going to see the very high combustion temps occationally also as you won't have to meet new emmisions legeslation you can dump more fuel in to reduce the exhaust gas temp. When OEM's don't fit them it's because the durability testing cycles are very harsh. For example a VXT engine won't make 240 bhp, meet emissions and pass durability testing but there are alot of stage 2's running around with no problems.

[speedster]

Thanks Winstar. What VGT would you recommend for a 2.2 motor then? For this engine I'm thinking of using ethanol as an alternate fuel. I believe it has an AFR of around 9 and it burns cooler than gas.

[Winstar]

I'm going to have to reply to this to night as it'll be a long one but in the mean time have a look thorugh these.

Turbo Tech 101 ( Basic )
Turbo Systems 102 (Advanced)
Turbo Tech 103 (Expert)

I expect you'll only need to look at the Tech 103, however there's some good stuff on compression ratio and AFR in 102, the rest gives a good guide to turbocharing. Thery're from the Garrett website but quite good info, although IMO not enough to match a turbo to an engine.

Rob

Edited by Winstar, 10 January 2007 - 01:10 PM.

[speedster]

Thanks for this Rob... Have to get out my log tables!

[Winstar]

I'd recommend as a first step to matching a turbo to the a 2.2 engine use the equations on the Garrett site to calculate the flow rate and pressure ratio at peak power and torque. Then I'm not sure it Garrett have an aftermarket department like our that if you give them these points that they'll help you match it to a compressor. You can then use this info to either find an engine with the same type of turbo and get a used one or remanufactured one. As a guide i'd expect a match for the engiento be one from either a 3L automtive engine or a 4L engine from a comercial vehicle, a swing vane one with electrical acuation for ease of installation The fact that you want to use ethanol as a fuel is an advantage it terms of the gas temperature, which should be good from a durability point of view and also the higher knock resistance matching the high pressure ratio characteristics of a deisel turbo. Howwever it could prove a problem in terms of match between the compressor and the turbine because in a deisel engine the AF is a lot higher than with alcohol so the mass flow through the compressor will be alot less than through the turbine. In fact if the engine is running EGR then the flow through the comp could be more then the turbine. A way to possibly get around this is to, as you initally said, use pre-compression injection to increase the mass flow through the compressor. This matching should be easier with a VG as the turbine stage is flexable but you could end up being in a part of the map that is not efficient enough to provide the power to drive the compressor to the required point on the map. Hope this helps, I'm happy to help you match a compressor and turbine to your engine requirements, but as some techniques are how our company does thing i can't do this on an open forum.

Edited by Winstar, 11 January 2007 - 09:39 PM.

[cyberface]

I'm not a professional engineer like some of you guys so my info may not be quite as useful as what's been said already. However until I swapped for the VXT I have had 3 Porsche 911s, have been and am still a Porsche enthusiast, and keep an ear to what's going on with their products. Luckily I prefer their earlier, more raw products, which is a good job since their new cars are too rich for my blood Anyway Porsche made a big deal about their VG turbines, primarily stating the fact that petrol exhaust temps were the challenge due to materials limitations, but road tests have unanimously praised the new turbo tech as being breakthrough; Porsche never had embarrassing lag on FQ-400 Mitsu levels due to the base 3.6 capacity torque delivery, but the new VGT appears to be a readily perceptible step up from previous fast-spool turbos. After all, previous 911 Turbos were never slated for lag - if anything, lag was the last thing anyone complained about (lack of flat-six character exhaust tone due to turbos and cats being major gripes). Now Porsche aren't stupid - they are well aware that they have a real dichotomy in their market - it's either the status-symbol brand-merchants (who hardly drive the things), or the hardcore Porsche enthusiasts (who spend half their miles on trackdays and constantly modify their cars). The enthusiast crew like the 911 Turbo because it's eminently tunable. Porsche's historical behaviour (allowing big tolerances) has given the Turbo-mod community the expectation that they can go to their favourite independent ECU-tuner and boost their Turbo to buggery. And so far, they've always been able to do that. Assuming Porsche haven't lost sight of this, then I'd assume that their VGT is engineered to cope with a good 20% more than retail settings. Many of their customers will head straight to Ruf, Manthey, DMS, Weltmeister or whoever they trust and ask for more boost (you could go to 9ff and get insane peak power but you'd need a new engine every week, hee hee). Many tuned 911 Turbos are so fast that the 'quoted' BHP from the tuner is well optimistic but the customer never cares because the car is still scarily fast. But breaking VGT parts will become a hot topic *very* quickly amongst the 911 megalomaniacs So from history and common sense I'd assume these units are capable of a damn sight more than the very impressive performance they give in the 911 Turbo. One unit on a VXT engine would be a rocket, assuming the unit control dimensions are handled by the VXT ECU, otherwise you're going to have to write your own software which is tricky. Bottom line to me (as a systems consultant, not a professional engineer) it seems that you can play with as many clever turbo units you like, regardless of the efficiency of the turbo the midrange torque figure tells you how much fuel you're burning, and the amount of fuel burnt determines the cooling requirements of the engine. If Thorney are right about the LET being hard to get to 285 in a VXT but an easy 400 in a front-engined massively-intercooled config, then surely it doesn't matter which turbo you use? As I said, I'm not a real engineer, but the fact that all the TMS maps I've seen have peak torque *well* above (in lb ft) peak power (in bhp) suggests that the engine config prevents the top-end from either dissipating the heat or breathing the air. I.e. the engine can't sustain the torque over 5250 or the peak power would be the same as the peak torque. I may be well off here, but I'll bet that a Porsche VGT unit costs a fortune, and all diesel VGTs are unsuitable, and even if you can get any of them to work, thermodynamics are more of a limitation than tricky turbo boost control mechanisms. I'd really appreciate the real engineers putting me straight if I'm talking shite here. I'm here to learn.