2.4 Bar Boost

[Billman]

So, after some playing with Paul's Excel files with the Garrett T04E Super 50 it came out that this turbo can make ca. 2.4 in the mid RPM field!

As a friend of the Forum told me: If you want people laughing at you then make a thread for 2.4 Bar boost; i am taking the risk

I know high boost levels ane not nessesary for high HP but for high Torque!!!

So what mods must be done in the I5 to cope with 2.4 Bar boost ? Had anyone experience with that amount of boost?

Thanks

[S2 Ant]

Toms hits 2.2bar i believe, so you will need to re-build your engine with a good set of rods for starters.

Mihnea and others will be able to comment on other bits like crank etc etc

[Billman]

These are somekind the figures, if i made no mistakes!

Thanks to PaulN:
Boost figures:

1000: 0
1500: 0
2000: 0,4
2500: 0,8
3000: 1,5
3500: 2,2
4000: 2,4
4500: 2,4
5000: 2,2
5500: 2
6000: 1,8
6500: 1,7
7000: 1,5
7500: 1,2

[Doug_RS2]

I'm hitting 2.2 bar

[Billman]

2.4 Anyone??

@Doug

Your mods are, pistons, rods and CR down? What about the Crank?

I think th problem will be when while driving with 2.4 bar knock occurs! What does the experts say?

Where are you Mihnea, Pisobiker, PaulN ..and the others..??

[Doug_RS2]

Some headwork as well.

Crank is standard - just balanced.

I am sure Mihnea could get mine to peak at 2.4 bar but boost isn't everything...

Instead of saying you want 2.4 boost, what power and torque do you want?

[S2central.net]

Torque IS proportional to boost, but 2.4bar sounds lairy to me...

Billman - I will investigate your scenario this week, but PLEASE don't take the excel as gospel truth - the maths is sound enough, but some of the assumptions are entirely untested (such as VE for example, and BSFC on our engines).

Certainly those kind of boost values will need a very strong bottom end - motorsport spec rods as a minimum, but would also recommend higher spec pistons and *maybe* reduced CR so you can get maximum ignition advance.

Really dunno if your calcs are correct yet - gimme a few days to get a look. Email your Excel sheet and the compressor map to me at s2central@mac.com


Paul

[Billman]

You can see above! With a relative small turbo over 540 NM from 3500 to 5500 RPM and over 400 BHP from 5500 RPM! I think these figures are very good for an all around car that pulls like Hell!!!

Again if i used the Compressor map correct!

[Billman]

@Paul
I just have seen your post! Sure you are right about the VE issues , but even if the VE is not exactly correct its a good direction for what the turbo good is!

I'll send you right away the maps and excels!

[audiman]

Stock rods will be on the limit at 590Nm, but i would go for some good ones. 2.4 bar is mental. Im hoping, depending on my clutch, that we can take my car to about 2.3 bar peak and tail it off to 1.7 redline.

Also gonna have some low boost chips done with flat 1.7bar boost, means i can have loads of ign. advance and more power!

[Billman]

I understand that the first thing to go are the Rods!

Good solution for these conversations is switchable programms! So you have one with full Power and one with good power but not extreme for touring and saving money

Another one is this using full compressor capabilities these figures:

1000: 0
1500: 0
2000: 0,4
2500: 0,8
3000: 1,5
3500: 2,4
4000: 2,6
4500: 2,5
5000: 2,2
5500: 2
6000: 1,8
6500: 1,6
7000: 1,5
7500: 1,2

I am Going Crazy with this boost!!!

[audiman]

2 bar @5500 will need serious low compression. And 3.5" exhaust system. It will pink like mad.

[Billman]

How low cr must be there?
What boost are the heavy tuned S2 having in 5500 RPM?

I thing if pinging is so much then would maybe water injection help too!

[audiman]

you will want 8.0:1 or lower IMHO.

[Pisobiker]

My stroker pinges a bit sometimes @ 1.6-1.65 bar boost with 98 ron fuel, even with my cr lowered to 8.7:1.
My problem might also be the intake was getting consistent amounts of oil vapours from the crankcase ventilation system, which I should have cured yesterday (at least I hope so), so I will see in a few days if the pinging disappears.
Anyway the pinging problem is real. Water injection is certainly a solution for running higher boosts before pinging occurs (apart from extra expensive racing fuels). Of course the system must be finely tunable through a CPU to take full advantage of it without the risk of damaging the engine.

About the ignition timing, I think there should be a compromise over ADVANCE vs. BOOST that works best, but as a rule of thumb I would say the best performances are achieved while tuning the best ignition advance at medium boost, then increasing boost up to where pinging starts.
There are many drawbacks in raising too much the boost while being then forced to decrease ignition advance to eliminate pinging:

1) decreasing ignition advance form what is optimum will reduce engine performances;
2) higher boost means higher charge temperatures which cause:
2.a) less charge density (therefore less power, again);
2.b) increased pinging (which takes back to reducing ignition timing again).....

So there is a point at which increasing boost will actually produce inferior outputs.....


Marco