Homefries boost figures

[Rusty]

As I said, there's a graph in the gallery...

[bertman]

And a very helpful graph it is

[Rusty]

Sweet There's some other graphs of power and torque for Homefries vs. Standard, just search under my username.

[Jamo]

Cheers for the figures Jamo

What point in the rev range should you see a drop off in the boost?

IIRC It's not rev controlled it's timed, the ECU overboosts for a set time then drops it's set limit.

S2central should be able to confirm or the info should be on www.s2central.net

[Rusty]

There's no overboost on a Homefries, it's simply a case of turbo lag in the lower gears. The boost profile is dependent on engine speed at WOT as per my graph.

[Jamo]

There's no overboost on a Homefries, it's simply a case of turbo lag in the lower gears. The boost profile is dependent on engine speed at WOT as per my graph.

Confirmed

http://www.s2forum.com/forum/showpost.php?p=314665&postcount=6

[HPmuirt]

ABY Homefry boost / gear profile

1st: 0.4 bar
2nd: 1.2 bar
3rd: 1.4 bar dropping to 1-1.2 bar
4th: same as 3rd
5th same as 3rd
6th: same as 3rd

Hmm, those figures just didn't look right to me, so I had a little blast at lunch time. My car is a boggo standard ABY with an RS2 MAF and airbox and a nice serving of Paul's homefries.

I did 2 runs in each gear, one normal (just booting from around 2000rpm) and one with more load (up hill and foot on brake ). I did not take the higher gears to red line for drop off as the hill is not that long (I am in the Fens remember). I saw: -

Gear: normal (load): -

1st: 1.1 bar (1.3 bar)
2nd: 1.3 bar (1.4 bar)
3rd: 1.4 bar (1.4 bar)
4th: 1.4 bar (1.4 bar)
5th 1.4 bar (1.4 bar)
6th: 1.4 bar (1.4 bar)

Basically I suspect the the homefires will give 1.4 bar in any gear if you can generate enough load for the ECU to run 100% boost - Although I expect I will now be proven wrong by Paul as he owes me a slap for taking the P recently

Cheers n

Si

[A80Avant]

how far did you on the higher gears then?

Cause when jamo says : drops to 1.2 to 1.3 means as the revs go up to the red line.Which means that 1.4bar can be from 2000rpm up to 5500rpm or 6000rpm and then dropping to 1.2bar gradually over 1000rpm range.(it can go steaper too).

[Jamo]

My tests wre not up hill but on a straight and I ran to redline where you could see the boost drop.

Yours are from load uphill which will produce different figures I would imagine.

Homefry Dyno runs should also show the boost drop

[HPmuirt]

how far did you on the higher gears then?

Cause when jamo says : drops to 1.2 to 1.3 means as the revs go up to the red line.Which means that 1.4bar can be from 2000rpm up to 5500rpm or 6000rpm and then dropping to 1.2bar gradually over 1000rpm range.(it can go steaper too).

Agreed, Jamo is quite correct there.

My boost certainly drops back to around 1.1 bar at red line in the higher gears, but this test was purely to see what the max boost is in each gear, which I reckon under homefries is 1.4bar in every gear.

Cheers n

Si

[Rusty]

1.5 bar or 21PSI should be max, more with load. Boost gauges don't read quite right, mine says 1.4 but the rolling road figures say 1.5...

[S2central.net]

Max boost in any gear is indeed 1.4-1.5 bar... That will vary a bit with temp and ambient of course and it does indeed reduce at the redline to stop the wee turbo from turning into a total hairdryer. Its hard to load up the engine enough in 1st and 2nd to get max boost of course - the easiest test is in 4th or higher from about 2000rpm... I did indeed delete the 'overboost' mode - the general consensus from users was that when you hit WOT, you want full beans regardless how quickly you opened the taps and we all know the gearbox can easily sustain more than 15 seconds of max torque on that setup.