55 replies to this topic

[speedster]

Thanks Rob for the additional details... I'm still working on an engine design and will keep you posted. Thanks for the insight cyberface Borg Warner are refusing point blank to give any technical details on the Porsche 911 VGT's (other than Porsche's part numbers) which makes me think they are currently under orders from Porsche to keep the specifications and configuration of the technology away from the public domain. It's going to be interesting to see how the tuners get on, will the maps and configurations for the VGT setup be as freely available as standard turbo setups? For my engine design my thinking is - Because of the materials used to build the Porsche VGT's the turbos (in theory) can operate better than a standard turbos in the higher power bands plus the VGT allows you to manage boost through the RPM range meaning, assuming the maths to manage a VGT have been worked out, one can be more precise tuning the engine. Another factor I'm considering is the use of ethanol as it pushes burn temperatures down which hopefully moves you beyond some of the heat issues that the VXT exhibits. Another point worth pondering is the all-alloy construction of the 2.2 engine, it will supply a engine with a different cooling dynamic which should provide an advantage over the LET! BTW I ain't an (automotive) engineer either so feel free to rip my theories to shreds

[Winstar]

Firstly I think that Porsche and the Borg's take on the materials used is probalby a bit miss leading and somewhat maketing spin. As after asking around you generally only use the materials you need to make a product durable, for example as our turbos are Heavey duty we use a higher grade of inconel than a pass car deisel would, then you would apply coating to this to make it more durable. The other thing is that all OEM's have different durability requirement and as said from the tuing that goes on I expect porsches to be some of the toughest. The other thing to consider is that the durability testing is far above what a normal car would see, and althogh peak gas temps would get up to the 900 deg C range it will only be peak conditions not the sustained temp found in accelerated testing. I think your main concern would be the effects of the ambient engine bay temp and its effect on the actuator as they don't tent to like sustained heat. The VGT offers better tuning as the intake side of an engine is determined by the inlet geometry of the engine which produces a breathing line, a VGT allow a small amount of exhaust gas to be used efficiently to create the right amount of power to drive the compressor. The construction of the L850 engine overcomes some of the problems with the LET cooling, the cooling system and oil system where both over speced to take into acount future developments of the base engine, whereas the LET base engine is a lot older and further along its developmnet life cycle. I would have a couple of concerns witht the 2.2 though. If you look at the SAAB turbo the used piston cooling oil jets but the cooler combustion temp of ethanol could negate this. One thing I would look at is using the stringer cast Al heat from the SAAB turbo engine though. Edit: You wouldn't be able to use the porchse VGT as the size is too small for a 2.2 engine.

Edited by Winstar, 12 January 2007 - 01:20 PM.

[speedster]

Me thinks the L850 sounds like a good foundation for high power and may make better sense than throwing money at a L61. Even the cams in the L850 are forged using newer technology and techniques.
Triple 8 have done some interesting work with it, and they're knocking back power to preserve the gearbox!! CLICKY

Edited by speedster, 15 January 2007 - 06:42 PM.

[Winstar]

Yeh the L850 is a good starting point, although I think I would be tempted to use the SAAB turbo version as a starting point as it has stronger component, better cooling and not to mention the oil feeds for the turbo already plumbed in.

[speedster]

Anybody know a supplier selling L850 engines, SAAB turbo version, in a crate? Can't find this unit listed on any of the inventories of the 'usual' crate engine suppliers.

[paulf-cam]

Anybody know a supplier selling L850 engines, SAAB turbo version, in a crate? Can't find this unit listed on any of the inventories of the 'usual' crate engine suppliers.

Wasn't Dude selling exactly that engine only just recently on this forum?

[Winstar]

you mean this, clicky.

Not sure which bolck, 2.2 or 2.0, it uses but has all the internal goodies for High Power.

Edit just noticed when it was posted, I'm sure it wasn't that long ago.

2n Edit: the new link

Edited by Winstar, 18 January 2007 - 01:11 PM.

[speedster]

Thanks guys.... I've PM the dude! Oh! Ethanol as a fuel is out. Running long-term with this fuel will lead to a break down of any seals it has long-term contact with and the effect on engine alu itself are been debated. Would of thought in this day and age the industry would be using materials that could resist a little alcohol. Maybe I'm a little ahead of myself Looks like I'm stuck with a oil burner!

Edited by speedster, 18 January 2007 - 01:48 PM.

[speedster]

Here's some comments from the crew on j-body

A lot of the VGT turbos used in regular diesels cannot withstand the heat from a normal gasoline turbo engine. Even though you will be running ethanol, you are still going to be hitting similar temperatures because you are going to tune the timing to the edge of detonation anyway. That's how the higher octane fuel can make more power.


I'm unsure about pure ethanol but E85 (what I'm using) is 100 octane.
Back on VGT, the whole reason I brought it up is beacuse you mentioned vanes. There are barely any vane-style turbos that are not VGT or VNT. (VNT is the same thing with a variable A/R compressor instead of the turbine.) The technology was found to be outdated a long time ago, a standard housing is a lot more efficient. You will be able to find VGT or VNT turbos which are purely mechanical and do not use a computer to tell it when to widen or narrow; these turbos strictly use a pressure diaphragm with an adjustable rod to adjust the boost curve.. but... good luck finding one. A lot of the newer cars are coming with some form of VGT turbo but they are not calling them VGT or VNT, they are calling them "electronically assisted." Only turbo luxury cars come with these like Porcche, BMW and even the new Nissan GTR. Some peole have had success using the control module for powerstroke electronic-actuated VGT turbos. I don't remember how they used it but it has been done.


About pre-turbo injection, people do water/meth pre-turbo injection all the time and I have never heard of a problem. Not to hang on Cosworth more, but they also use an 18-injector set-up using two injectors per cylinder in the intake manifold and then two injectors spraying before the turbo. As I said before the gains are achieved by a cooler compressor wheel. The wear that the ethanol may cause on the turbo is going to be terribly minimal if at all.


Any comments

And E85 (85% ehtanol + 15% petrol) is available from a number of suppilers here too! I should be able to map the engine for that.....

Edited by speedster, 19 January 2007 - 12:25 AM.

[paulf-cam]

Any comments

And E85 (85% ehtanol + 15% petrol) is available from a number of suppilers here too! I should be able to map the engine for that.....

I would be very wary myself of injecting a flamable fuel before the red hot turbo...

In fact any liquid before the turbo is probably asking for trouble one way or another.

I'd be interested in a variable vane turbo which wasn't computer controlled - it might go well on my TD mini monster truck...

[Winstar]

Can you post the link to the thread.

Back on VGT, the whole reason I brought it up is beacuse you mentioned vanes. There are barely any vane-style turbos that are not VGT or VNT. (VNT is the same thing with a variable A/R compressor instead of the turbine.) The technology was found to be outdated a long time ago, a standard housing is a lot more efficient.

What he means is all modern turbines use vaneless nozzels rather than vaned as it gives a better operating range at the expense of efficience at a specific design point. Er no, a VNT isn't variable A/R compressor, it's Garrett marketing speak for their copy of our design of VGT that uses a sliding nozzle. Nobody makes a VGC yet as current comp technology is good enough, prob won't as modulated turbo charging as in the BMW 535D is a far better solution.

You will be able to find VGT or VNT turbos which are purely mechanical and do not use a computer to tell it when to widen or narrow; these turbos strictly use a pressure diaphragm with an adjustable rod to adjust the boost curve.. but... good luck finding one.

I'm not saying you couldn't but it's such a crude method of actuation that I doubt you would be able to calibrate it well enoough to meet modern emissions legerslation so manufactures wouldn't use it. Most purely mecanical actuators only drive a 2 position wastgate that operates at a given comp boost pressure against a preset spring, the one on the VXT uses a solenoid to triger the wastegates.


As for injecting fuel to a 'red hot' turbo, the compressor side of the turbo in spark injection should only be just above 100 deg C, even at a 4:1 pressure ratio our outlet temps are less than 230 deg C.

Ethanol shouldn't cause any wear in the comp end as every thing is metal, the only danger is that you get combustable material blowing by the comp end seals and into the crank case if the pressure behind the comp wheel is greater than your oil pressure, highly unlikely but we use special seals for our gas generator engine turbos.

Edited by Winstar, 19 January 2007 - 01:16 PM.

[speedster]

Thank Rob. Complete thread is HERE

I aint making a BBQ Paul! How's that rocket of yours doing?

[paulf-cam]

I aint making a BBQ Paul! How's that rocket of yours doing?

I dunno about rocket - more like huge lumbering beast! Its in the workshop getting a new engine / new springs and a cross-over steering conversion. Mucho ££££.

Its getting a 3.0 turbo diesel engine put in it which is why the mechanical VVT turbo idea sparked my imagination...

[speedster]

The construction of the L850 engine overcomes some of the problems with the LET cooling, the cooling system and oil system where both over speced to take into acount future developments of the base engine, whereas the LET base engine is a lot older and further along its developmnet life cycle. I would have a couple of concerns witht the 2.2 though. If you look at the SAAB turbo the used piston cooling oil jets but the cooler combustion temp of ethanol could negate this. One thing I would look at is using the stringer cast Al heat from the SAAB turbo engine though.

How does the piston cooling function in the L850 or later sc/turbo engines? Is it due the design or structure of the pistons, or the does the block have a specific design for throwing oil around?

[paulf-cam]

How does the piston cooling function in the L850 or later sc/turbo engines? Is it due the design or structure of the pistons, or the does the block have a specific design for throwing oil around?

I believe it has oil squirting jets in the block which coat the underside of the pistons...

[Winstar]

How does the piston cooling function in the L850 or later sc/turbo engines? Is it due the design or structure of the pistons, or the does the block have a specific design for throwing oil around?

I believe it has oil squirting jets in the block which coat the underside of the pistons...

The oil piston coling jets are small nozzles that come off the main oil gallary that spray a constnt jet of oil onto the bottom of the piston. The angle of these jets is such that as the piston moves up and down the point at which the jet hit the bottom of the piston moves along the piston and back again. ie at TDC the jet hit the far edge of the piston and vice versa.

Edited by Winstar, 23 January 2007 - 12:36 PM.