The people in Australia running STi 7's and 8's seem to think more than 1.2 bar held on a VF 35 is too much boost for a VF35. Anyone got an opinion on this. PPP and Ecutek guys ;-)))

 

1.3 bar held until about 5.000 RPM is absolutely no problem for that turbo on an STi!

Mark.

 

but only to 5000rpm? That's not really held then is it?

What about 7000rpm?

Paul

 

1.3 bar held from 2800 RPM up to 7000RPM on my STi7. No problems, no det (but injectors duty-cycle > 90% over 6500RPM!).
My opinion is that Turbo can deliver even more.

 

XNWRX

What does 19.87mS injector pulse width translate to in duty cycle?

I am getting 1.35 bar from 3300rpm dropping slowly to 1.25 bar at 6000rpm then dropping to 1.1 bar by 7000rpm on my VF35.

 

depends on the RPM. For example 19.87ms = 90% @ 6000RPM and equal 116% @ 7000RPM
Formula is DC(%) = RPM.T(ms)/1200

over 90% = max and can lead to det (lean fuel mixture)

 

Formula is DC(%) = RPM.T(ms)/1200

So using formula 15.1ms at 7000rpm = 7000 X 15.1/1200 =88%
Correct?

For 19.87ms at 6000rpm I get 6000 X 19.87/1200 = 99.35%

I am doing something wrong?


[Edited by GDBSTi - 6/13/2003 8:16:23 PM]

 

XNWRX,

Good luck! I guess 1.3 bar @ 7.000 is realy too much for that turbo, it will produce massive charge temperature. Do you use a FMIC?

I am running my customer cars at 1.3 bar until 5.000, 1.2 @ 6.000 and 1.1 @ 7.000. With good mapping of ignition and fueling you have a very, very well going car with nice torque from 3.000 - 7.000 RPM. My experience with higher boost @ high revs (with the standard intercooler) is that you have to reduce advance and increase fueling to keep it det free, in the end you have hardly any gain in power.

P.S. I didn't saw compressor maps yet for the VF35, but I don't think it will be very different compared to a VF23. The VF23 is running very inefficient over 1.2 bar @ 6.000 RPM and over 1.1 bar @ 7.000 RPM.

Mark.

 

GDBSTi, you're right, 99% at 6000RPM with 19,87ms pulse width, I made a mistake when calculating ! But again, 90% is the maximum safe DC.

EMS, I agree with you : 1.3 up to 5000, then 1.2 upto 6000 then 1.1 up to 7000 then 1 is perfect for good performances and reliability.
I understood the question was : "can a VF35 maintain 1.25 bar at 7000" ? the answer is YES, and even more, but out of its efficiency area.

On my car, I finaly tune 1.3 from 2800RPM up to 5600 (5800 is the RPM where the knock sensor is no more used for knock correction), then 1.2 upto 6500 then I close the soleno for the boost pressure to decrease down to 0.7bar (no need for boost or power after 6500RPM).
From 5600 to 7500, I richen the fuel mixture for reliability and T°.

 

XNWRX

Whats your opinion of these figures

In 4th Gear,

1.35bar (17.92mS IPW =49.3%IDC) at 3300rpm reducing to 1.25 (17.66mS IPW = 88.3%IDC) bar at 6000rpm reducing to 1.1bar (15.36mS IPW =89.6%IDC) at 7000rpm.
Maximum Injector pulse width = 19.97mS at 4491rpm = 74.74%IDC

and in 5th Gear

1.37Bar (17.66mS IPW) at 3156rpm reducing to 1.3bar (17.66mS IPW) at 6000rpm then 1.16Bar(16.13mS IPW) at 6696rpm.

and in 6th Gear

1.4bar at 3078rpm (18.94mS) reducing to 1.3bar at 6000rpm (17.73mS) then I was going too fast ;-)))))) to keep logging.

All IDC are less than 90%, no knocking on Knock Link, no negative knock correction on Delta Dash.

I am running 102.6RON leaded racing fuel.
Does fuel RON effect the efficiency of a turbo?

[Edited by GDBSTi - 6/14/2003 8:57:11 AM]

 

it can be fine, except that you should not use your knock link to monitor knock as it is not efficient.
No negative correction : try to keep knock correction above 4° which will give you better performances.

The RON doesn't effect turbo efficienty, it only gives you more margin to run without knock and allows you to run more boost and/or leaner with advanced ignition...so more power.
If you try to run with those setup with 98RON, your car should det.

 

XNWRX,

The knock correction on an STi (7 and 8) is definitly working until about 6.200 RPM!

O.K. I have no doubt the VF35 is able to produce 1.3 bar until 7.000, but what you already said it´s (way) out of it´s effective zone.

Mark.

 

I tried running on 97RON and got lots of detonation on Knock Link, but never less than +4 degrees knock correction (minimum +5.5 Degrees). Retarded timing by 5 degrees with Delta Dash and only got occasional knock on Knock Link. However never got less than +4 degrees knock correction before 6200rpm (minimum +8 Degrees).

Tuner said its supposed to work fine on 97RON , but car is much happier with 102,6RON (no retard applied, not more than +9 Degrees Knock Correction on DD, only first green light on Knock Link in 6th gear at 6500rpm ;-)) )

I suppose racing cars want racing fuel;-))))

[Edited by GDBSTi - 6/14/2003 11:34:45 AM]