2871R Estimates for Diesel Des

[S2central.net]

Des - As per PM... Here goes - not had time to plot on the map yet - these CE values are what I had before for a GT3071R - think its same compressor. Talk again soon. Didn't have your email addy to send as an attachment.

[Rusty]

Those are some pretty intersting figures ther Paul. Max torque seems to come a little later than I might have expected. Is this a .63 trim or .82?

[S2central.net]

Its the .63 - I'm pretty sure... I used the same boost profile as some of the motorgeek folks and it compares pretty well with their findings on the rollers - with at the wheels measurements. On paper it looks like Bosch greens (42lbs/min @ 3bar) should be enough, but its close, so the Motorgeek folks moved up to chunky 55lb jobs. Des has the same ones now so I've got a challenge to adapt the fuelling for those babies... I think I can get him some more boost than the fairly conservative levels he has today. Gonna be fun - or a nosebleed !

[Rusty]

The boost drops off fast up top, is the turbo through it's sweet spot by then? Any chance of a comparison between .63 3071 running the same max boost thus for OE rods, .63 2871 and high boost RS2. Be interesting to see what the theory says the advantages are as the RS2 option is so much cheaper at the mo.

[Jamo]

Seems about right

http://www.s2forum.com/forum/showthread.php?t=13585&highlight=400&page=3

[Rusty]

That's 50fly hp more than Paul's estimate and 10 more than the only 3071 car I've seen (Ross's).

[Jamo]

http://www.s2forum.com/forum/showthread.php?t=5297&page=6

Kalsket got 458hp/519Nm, (513Nm @ 3700rpm)

Spec:

ADU-std: pistons, bearings, in-cam, valves, compression, in-manifold, injectors and fuel pump
AAN-ex.cam (in order to compensate too freely flowing ex-side head)
Verdi rods
Head done by Kansiset, intake max flow 312 Hp
Tube header and downpipe by Pro-mo
Turbo GT2871R, (turbine housing 0,64 A/R) with internal wastegate
Boost control std. Motronic
Exhaust 3" turbo back, no cats
1.7 bar.

IMO It's doable but you must have a good setup i.e ported head, 3" downpipe and exhaust, tuning etc.

From the 3071r setups i've seen most are stock bolt on's Ross could have got more out of his setup with larger injectors which was planned.

[S2central.net]

That audiclub RS2 with 2871R graph doesn't align with the AAN spreadsheet I have and the motorgeek dyno runs... Look at 4000 rpm at 1.8bar boost - my power estimate is a long way shy of that Finnish graph -and their torque gets a mighty boost as a result compared to my numbers and motorgeek run. Is this due to the RS2 camshafts and timing, or exotic fuel, or extremely cold air (the RS2 ECU loves that) on the Finland run or somebody smoking something ?

Paul

[Jamo]

I'm sure Kalsket is still around maybe he could chip in?

[Rusty]

Properly flowed head will make a large input to that figure IMO.

[EspenW]

That graph is yet another guesstimate of flywheel power from a rolling road measurement. IN real life, power loss (in percent) is lower at max torque than at max power, and they used a flat 25% correction at all rpms, overstating the torque.

[S2central.net]

Ahhh OK - that makes sense Espen... I've often used 25% as a good rule of thumb for quattro drivetrain losses - never had the time or interest to get into details of this subject, but are you suggesting a lower correction value in the lower rpms is more realistic ?

Got any good sites (or your own words) that explain this drivetrain loss subject without getting carried away in detailed mechanical equations - just need some reliable / proven estimates that are valid.

[EspenW]

Drivetrain consist of various components:
One component that is static (seal drag, etc)
One component that is dependent on load (torque)
One component that is dependent on rpm (windage effect, etc)

Thus: two cars with identical drivetrains and identical max flywheel horsepower rating can see different horsepower at the wheels if that max power is made at different rpm.
A turbo diesel that makes say 300hp at the flywheel at 3500rpm is going to have a different whp figure than for example a high strung NA 4 that makes 300hp at 9000rpm.

Turbo engines usually make lots more torque than NA engines, so the loss in percent will often be more constant than what is the case with NA, but still, just applying a fixed % at all rpms is inaccurate.

[diesel des]

Just saw this thread Paul. Where have i been. lol. Yea Pauls doing well getting his head round these big injectors. The car was on RS2 injectors and they were going 100% duty between 6-7K rpm with a 4 bar fuel regulator. AFR was at about 12-13:1 at that time. Im guessing that it had to be 400+ BHP. 1.5 bar bost from 6-7K rpm. Trying to get it setup on the larger injectors now. We will keep you informed as to how we end up but all i can say is Paul is very good!.

Car spec is:

Stock AAN bottom end and head
Steel gasket
ARP studs
Big front mount intercooler
Gt2871R
Custom 3 inch down pipe

Cheers,des.

[Jamo]

RS2 injectors maxed out at 4 bar? wow