VR4 max boost on standard turbos??

[pitslayer]

Sure I read on a previous thread that in the uk fuel cut is much more prominent than in NZ, something along those lines, sure Brad posted it up something about temp difference, I cant really remember, but I am sure I have read a few times that 18psi is the max, efficent, but 20psi can be seen

As for search, yeah I gotta agree though that the search function here is utter poo, and you end up spending half hour trying different phrasing, what really needs to happen is getting this thread updated and making it much more easier to see
http://clubvr4.com/forum/showthread.php?t=18493

[Turbo_Steve]

The difference in fuel cut will be down to air density: the MASS of the air is the significant factor, so at a different altitude (what height are you above sea level?) air temperature and perhaps more significantly in the case of NZ, humidity level, you will potentially require more air to reach the same pressure.

Let's not lose sight of the target here: boost pressure has very little to do with the turbo, and has everything to do with the trying to force a given amount of air through a specific restriction (an engine).

[AlanDITD]

Are you forgetting the pissing compressor outlet we have, i would say thats another huge restriction.

I cant understand that at all when the rest is 2. 2.5 and 3" its just a bit barmy.

[Turbo_Steve]

LOL...but that is done for a reason!
That turbo outlet is still rated to the maximum flow, and is part of the shape of the compressor map. Opening it out MAY improve top end efficiency, however it can also cost you lower down as you're changing the compression profile of the scroll: the whole principal of the compressor is building up resistance to actually achieve compression: hence why the pipework should progressively get larger from the turbo to the inlet to maintain good flow, and why really good intercooler design is so goddamn complicated!

[Dom B]

I have been looking furiously for td03 maps but i can only find td04 and bigger maps.

Talking about the bearings not hacking it i saw some excellent tests with ball bearings against oil film bearings and it showed that the ball bearing had 50%+ less friction at low boost but the higher it got the smaller the gap was and on full boost the ball and oil bearings were almost identical.

I do know that the higher boost levels affect our thrust bearings first. I have seen 360degree replacements that have a 10-20% more load bearing capacity. The higher boost levels push the compressor back and the thrust bearing hits metal as the oil film cannot support it against the shock boost loads.

Brads car is obviously more volumetrically efficient. He must have a lot of larger hard pipes, perhaps a bigger intercooler and maybe a bigger airbos and throttle body too???

Perhaps cavemans set up is more stock but with a higher boost?????

Is this correct at all?

[Kenneth]

Brads car is obviously more volumetrically efficient. He must have a lot of larger hard pipes, perhaps a bigger intercooler and maybe a bigger airbos and throttle body too???

Perhaps cavemans set up is more stock but with a higher boost?????

Is this correct at all?

Brad has a 600x300x100 intercooler.
I believe all his pipe work is 2.5" aluminium, custom made and he has a standard throttle body.

Brad runs separate intake pipes to each turbo, each with its own pod filter. These reside in a shielded box where the battery would usually be.

He also has 2.5" down pipes into 3" main pipe which leads to a duel exit exhaust.

[Dom B]

Brad has a 600x300x100 intercooler.
I believe all his pipe work is 2.5" aluminium, custom made and he has a standard throttle body.

Brad runs separate intake pipes to each turbo, each with its own pod filter. These reside in a shielded box where the battery would usually be.

He also has 2.5" down pipes into 3" main pipe which leads to a duel exit exhaust.

Has brad also deleted the MAF??? Or does he put it at the entry to the airbox?

[Kenneth]

Has brad also deleted the MAF??? Or does he put it at the entry to the airbox?

Brad runs an Autronic SM4 fully standalone ECU and has no MAF.

His car was also tuned and setup by a respected tuner who IIRC does a lot of work on competition cars.

[hi flyer]

I've seen 28psi or tad under 2 bar on our td03s, but they were hi-flowed. It had a few other mods. Very quick car.

[bradc]

Back on topic about my car, click on my name then go to see my car. You'll see the engine bay piping and so on. I do have the larger 64mm throttle body, some VR-4's came with 60mm ones.

Caveman has put up external pictures of his car but nothing showing the enginebay. What I do know is that whatever power his car recorded at the wheels - I think around 205kw sounds familiar, he has an auto so will lose about 7% extra over me, so he would be at about 220kw ATW with a manual

[Turbo_Steve]

I'm no sure I agree with the use of the term VE in this instance, but yes, brads setup does not incur many parasitic breathing losses: the worst is most likely the pressure drop across his intercooler.

As Ryan points out, I would be interested to know what difference porting the turbos would make on a car like brads: I suspect it would be a lot of effort for minimal gains.

I'm sure we posted up the compressor maps for our turbos somewhere....I'll do some searching.

The brearings themselves actually don't seem to be the problem: do a quick search on TD03 Hybrid, and the first thread you see goes into great detail.
We've been looking into hybrids and all sorts, but by the time you've bored enough meat out of the exhaust housing, you may as well have simply fitted a TD04 compatible turbo and made up some downpipes.

Don't get me started on ECUs

[Kelly&Ben]

surely the simple answer is you can run whatecer boost you like max on standard turbo's 3 bar if u like... they wont last 2 seconds tho so about 1.2bar is max i believe b4 they just become heat guns and all small turbo's loose boost top end. i used to have a blit k24 on my old car. even that at 1.3 bar would tail off to 0.9 up top of revs

[Dom B]

surely the simple answer is you can run whatecer boost you like max on standard turbo's 3 bar if u like... they wont last 2 seconds tho so about 1.2bar is max i believe b4 they just become heat guns and all small turbo's loose boost top end. i used to have a blit k24 on my old car. even that at 1.3 bar would tail off to 0.9 up top of revs

It's not quite that easy. At the flow rates we are discussing the td03 cannot supply enough air. My question was aimed at just how much air mass can the stanrd turbo supply before it hits this point when at max revs. You can certainly spike the boost to a very high level at lower rpm where the engines air consumption is within the flow rate of the compressor and of the exhaust flow rate of the very small turbine, after this the turbine starts causing surge against the compressor flow which is multiplying cubically with speed increase. Really a turbo is only very efficient at one speed and flow, but the manufacturers work with this limitation. Its a bit like car engines are only really designed for 1 speed but they have ways of getting a wider spread of power to make a car usable.

Excellent point about the heat though, after the efficiency limits of the compressor are reached most of the energy goes into heating the air and then the thermal barrier of what the intercooler can deal with is reached.

The problem i have at present is that i can only find td04 compressor maps and am still searching for td03 ones. Someone mentioned that there were some on here a while ago but so far i haven't managed to find them.

[Ryan]

So dom are you ever going to tell us what you actually do then

I have to say though, whenever i use the search function it pops up most of the answers i need. But then im looking for fixes or basic questions rather than the more technical information like this thread was started for.

I think the search is very good for that, and all the info re fixes and tech info is already in the members resource area.

Well anyway an interesting thread,

whats the max flow rate of td03's anyway

Not sure if this answers your question Alan:

Urghhh - stupid upload crap doesn't work properly.

Try here: http://img99.imageshack.us/img99/5783/turbospecs.gif

^ originally uploaded by Kieran but can't find it!

[Mark 4]

http://www.clubvr4.com/forum/showthr...light=td03+map


Simple search - "TD03 map"

[AlanDITD]

Cold night up here tonight peaking 15psi holding 14psi most of the way then a small drop to 12psi in the last few revs.

Fuel cut alot easier though, had a scary moment powering into a corner a quick boost spike and the car cut power AYC does nothing then it seems.

Anyway cheers for the links, what is it you have planned dom?

Steve just to go back to the point earlier about building in restrictions, i.e the skimpy compressor outlets we have, Can you explain a bit more? Is there any benefit then to porting the compressor outlet, the compressor inlet etc etc.

[Turbo_Steve]

To be truthful: I don't know. My understanding is that there needs to be sufficient restriction within the turbo for it to actually achieve compression, though I would have thought this could be achieved against the resistance of the valves themselves.

[AlanDITD]

Hmmmm i always thought the more free flowing from the turbo the better. Simply because most bigger powered cars tend to run either 2.5" or 3" all the way round to stop any restrictions. That was a 400p cossie and the mental 488hp corsa.

But yeah i thought all the restriction would have started intake runners where the air slows down and splits.

Also dumpvales are there to stop the turbo stalling when backed up air from the throttle body closing. In theory is it not kinda the same? any restricion causes air to back up onto the turbo either causing it to stall or in this case get very very hot.

Thats all just an educated guess though, i know nothing about turbos and efficiencys

[psbarham]

To be truthful: I don't know. My understanding is that there needs to be sufficient restriction within the turbo for it to actually achieve compression, though I would have thought this could be achieved against the resistance of the valves themselves.

yeh as above a pressure is only achieved with a restriction, for example get a pressure washer and take the lance off the hose and the water just runs out, put the lance and nozzle on it and the water coming out will come out at what engineers call a "fair old lick"

[AlanDITD]

yeh as above a pressure is only achieved with a restriction, for example get a pressure washer and take the lance off the hose and the water just runs out, put the lance and nozzle on it and the water coming out will come out at what engineers call a "fair old lick"

So it will increase spool time, not overall pressure over an RPM range?