VR4 max boost on standard turbos??

[Nick Mann]

Please note - his thread has been severely edited to keep it on track. Only the relevant information has been kept. The original thread, which became a discussion on the use/usefulness of the search function is now here:

http://www.clubvr4.com/forum/showthread.php?t=39753

[Dom B]

Does anyone know off hand and from testing what the maximum boost the stock turbos can deliver at max rpm air flow rate. I have heard that they struggle when the air flow gets high at the higher end of the rpm scale. Mine certainly has little top end.

[Wodjno]

Search is your friend

[Dom B]

search is only as good as the phrase you enter and unless you know exactly what the thread was then you don't stand a hope in hell of finding it.

All you searchers please point me to the Compressor flow maps of the turbonetics turbo chargers we have in the wheel trim we have.

[Wodjno]

there is NO specific exact Max boost level figures..
And this is quite clear in the Gazzilion threads and posts of the forums about the said subject.
Some have managed to maintain 1 bar to the redline, but very few. 0.85-0.9 bar seems the average. But every car is different..
Wear and tear on a multitude of engine elements determine that.
Also dependant on how individuals are boosting there car and any supporting mods also.. Wear and tear on the Tub's themselves i would say is the largest factor.
So 1 bar for me and a few.. 0.9 for most others..
But like i said.. It has been posted and talked about many times and you will find that the information is conclusively inconclusive..

And i still say Search is your friend.. As any info given in this thread is by members that have contributed to other threads in discussion about the same subject..

PS.. And if we removed all the Treads that have been posted cos no bugger used the search long enough to find the info they required ! Then the database would be 1/5th the size.. And i would say that is more fact than conjecture for removing search posts..

[Nick Mann]

No idea!

I have had over 1.0 bar at 6800 rpm, but I can't tell you how efficient that is. When wiring a boost solenoid incorrectly I have recorded 1.6 bar in 4th on hitting the loud pedal.

[Dom B]

/ignores previous 5 posts....

No idea!

I have had over 1.0 bar at 6800 rpm, but I can't tell you how efficient that is. When wiring a boost solenoid incorrectly I have recorded 1.6 bar in 4th on hitting the loud pedal.

Ahh some numbers, now we are talking, that is an answer to my question. thanks nick, have some rep.

It rather strikes me that these small but efficient turbos are quite capable of a lot of power. Some people say they are maxed out at 350bhp and others have recorded 400bhp+ on standard turbos.

Regardless of the pipe work, the actual turbo unit itself should be good for some serious flow rates. Sorting the restrictions in the pipework is the technical challenge that we can enjoy.

If we can hit basically 1 bar (14.7psi) then we should be able to extrach a decent ammount of power. I also get the impression that the fuel cut is the biggest problem getting more than 1bar and not the turbos themselves.

Did i read right that the guy with the very powerful FTO was using only 18psi of boost? That is not far off. 1.25 bar or so.

[Wodjno]

Ahh some numbers, now we are talking, that is an answer to my question. thanks nick, have some rep.

So my figures didn't show up in your search of this thread

[Dom B]

Well i did find a few references to 1 bar but they always talked about fuel cut being the stop point meaning that the figure was hidden. what i want to really know is what they are capable of maybe from a standalone aftermarket ecu test mule.

I am up for doing some decent testing. I have some dyno facilities so can get some half useful figures out, its not great but is a good comparitive test. Unfortunately i have decided against a megasquirt ecu at the moment due to the complicated interaction of the ecu with all the other systems like abs, ayc, air con, dash panel etc. I have to do more research on how i can leave the original ecu in place with some dummy loads but it not get thrown by the megasquirt ecu changing things, and the two units fighting each other.

[Wodjno]

I held 1 Bar to the redline "Just" With no fuel cut..

So Fuel cut is not the underlying factor in not being able to hold anymore..

I was running an uprated pump, E-manage Ultimate, Larger FMIC, some hardpipes and a Greddy profec E-01..

lots and lots of ON ROAD testing done..

[Dom B]

I have been doing some rough calculations. It seems that for 7000rpm for example that a 2500cc (i know it's just under this) and pushing 2.1bar of boost Absolute (so 1.1bar relative) needs 549.5cfm of air or 38.5Lb/min. This should relate to 366bhp at 1.1bar boost.

Do those figures sound somewhere in the ball park from known cars out there?????

WodJNo does this sound somewhere around what your car gives?

I am still searching for the compressor maps of the 03 turbos that we have, i can only find td04 maps so far.

[Wodjno]

Never did get a good run on the rollers.. As the extra loading of the rollers induced fuel cut
So i think the Max was around 320ish..

[Dom B]

So the figures are not far off taking into account that i uses 1.1bar to be just over.

[Nutter_John]

cavemans runs at 1.2 bar and produces 345 bhp

brads runs 1.1 bar and produces 375 bhp

Anything above 1 bar the and amount of heat being pushed out of the turbos is huge therefore you lose power due to running higher temps

[Turbo_Steve]

There are compressor maps for them somewhere (dare I say to search for TD03 and compressor map!?) and it shows them to be progressively less and less efficient beyond 400cfm (IIRC). Btw, I agree the search function is poo.

Generally, it appears the bearing setup in our turbos can't hack it.....brads power tails off past 5000rpms.

[bradc]

My max power is at 5300rpm, and the car is above 200kw at the wheels from about 4300rpm to 6800rpm or thereabouts. It peaks at 1.1 bar and spends most of the graph at about 1bar. My 228kw ATW is the highest I've seen at the wheels for any car with stock turbos.

[Wodjno]

My 228kw ATW is the highest I've seen at the wheels for any car with stock turbos.

[Turbo_Steve]

But it must be remembered that brad has a nice big intercooler, and (more importantly) an entirely custom map, presumably with plenty of timing and perfect fuelling to make the most of it.

Also, whilst pressure is important, it's actually flow, and not pressure, that the Fuel Cut will operate on. So a more restrictive inlet, or throttle body, or whatever, will push up the pressure for equivalent flow.

[bigoxo]

have seen 20psi on mine but not for long as i crapped my pants - i set the MBC up wrong, i now run at around 12psi.

[Ryan]

I've seen mine spike at 17psi on a cold evening.