Manifold temp will be higher than air box for sure but all other things being equal which they probably are the delta between ambiant and mesured should be the same. That's what counts as that is what the dme sees.
Sharing CAI data
- Thread starter Sajk
- Start date
Pingu what engine do you have. I have built my 2.8 a little with a 3.0 inlet manifold and bigger cams to try to get back to stock air flow at sea level as I am at 6k feet. Not getting anywhere near 800kg per hour air flow though..... this is what I think I see in your graph data?
- Joined
- Dec 8, 2011
- Points
- 145
S50 at 30m above sea level with 15 deg C ambient.
3.2 litres @ 7500 rpm x 60 mins/hr divided by 2 = 720,000 litres / hr = 930 kg / hr (at 100% volumetric efficiency)
2.8 litres @ 6500 rpm x 60 mins/hr divided by 2 = 546,000 litres / hr = 700 kg / hr (at 100% volumetric efficiency)
- Joined
- Dec 8, 2011
- Points
- 145
( 2.793 x 6800 x 60 / 2 ) x 0.0012929 = 736 kg / hr
620 / 736 = 84.2%
I'd be aiming for between 90% and 95% ( 660 - 700 kg / hr ).
Data for my test run (taken from the raw Testo data)...
( 3.201 x 7401 x 60 / 2 ) x 0.0012929 = 918 kg / hr
VE = 860 / 918 = 93.7%
I've heard that the S50 can be tuned to be higher than 100%, but that is race tuning, and would be almost impossible to drive on the roads.
The main problem with using data like this is that the sample timestamp for the rpm and the sample timestamp for the air flow rate CANNOT be the same, as data can only be snapped one item at a time, even though it is given the same timestamp. A lot can happen in a millisecond. Testo records 27 items every 200ms. There could be as much as 200ms between the rpm measurement and the air flow measurement. The crank will have turned 25 times in that time.
For example, here are the 6 consecutive datasets with full throttle...
This is why readings should only be trusted when the system is at steady state. An IC engine's parameters are constantly changing and there is never a steady state situation. The best that you can hope for is an ALMOST STEADY STATE. The problem with that is the readings for an engine running at a steady 7,000rpm will be different to the readings for an engine that is accelerating hard through 7,000rpm. It is the readings for the hard accelerating engine that we really want to measure, but we can't
620 / 736 = 84.2%
I'd be aiming for between 90% and 95% ( 660 - 700 kg / hr ).
Data for my test run (taken from the raw Testo data)...
( 3.201 x 7401 x 60 / 2 ) x 0.0012929 = 918 kg / hr
VE = 860 / 918 = 93.7%
I've heard that the S50 can be tuned to be higher than 100%, but that is race tuning, and would be almost impossible to drive on the roads.
The main problem with using data like this is that the sample timestamp for the rpm and the sample timestamp for the air flow rate CANNOT be the same, as data can only be snapped one item at a time, even though it is given the same timestamp. A lot can happen in a millisecond. Testo records 27 items every 200ms. There could be as much as 200ms between the rpm measurement and the air flow measurement. The crank will have turned 25 times in that time.
For example, here are the 6 consecutive datasets with full throttle...
| Timestamp | Throttle Position | RPM | Air Mass |
|---|---|---|---|
| 13.8 | 98.4422 | 6557 | 782 |
| 14.0 | 98.4422 | 6720 | 786 |
| 14.2 | 98.4422 | 6887 | 804.5 |
| 14.4 | 98.4422 | 7072 | 822.75 |
| 14.6 | 98.4422 | 7246 | 840 |
| 14.7 | 98.4422 | 7401 | 860.5 |
This is why readings should only be trusted when the system is at steady state. An IC engine's parameters are constantly changing and there is never a steady state situation. The best that you can hope for is an ALMOST STEADY STATE. The problem with that is the readings for an engine running at a steady 7,000rpm will be different to the readings for an engine that is accelerating hard through 7,000rpm. It is the readings for the hard accelerating engine that we really want to measure, but we can't
I figured it was about 85% based on the math I did. This is an m52tu operating at 5500 feet above sea level. I am probably at around stock flow at sea level given I have 18% less air to work with. Before the cams and the m5430 intake we struggled to log above 450 to 490kg p/hour...
I don't think any m52 platform would operate at 95% VE but whst do i know actually.
Edit.
A lot can happen in a millisecond.
Yes I am a software engineer. It's a loooooong time.
I don't think any m52 platform would operate at 95% VE but whst do i know actually.
Edit.
A lot can happen in a millisecond.
Yes I am a software engineer. It's a loooooong time.
- Joined
- Oct 19, 2014
- Points
- 174
- Model of Z
- 2.2i Sport
There, fixed that for you.Personally, I'd rather have an engine that screams like a banshee and sod the stereo
- Joined
- Dec 8, 2011
- Points
- 145
Where in the world? 5,500ft is over 1,000ft higher than our highest mountain
. I got light headed at around 7,000ft in Italy and the 330 really started to suffer as well.
- Joined
- Dec 8, 2011
- Points
- 145
Have you considered a supercharger?
A supercharger that is designed to squeeze air at 15psi should have no problems squeezing air that is only at 12.5psi.
- Joined
- Dec 8, 2011
- Points
- 145
Nottingham, UK. Highest mountain in UK is in Scotland - Ben Nevis.
Yes i have on on my JK wrangler with the old 3.8 minivan engine in.It helps a lot. With that engine, and ancient far to high geared 4 speed auto and 17 pct less power than at the coast that thing would sometimes drop down to second gear on the highway at the first sign of a rise in the road approaching 6500 feet.
If have thought a lot about boosting the Z or transplanting an S54. IT WOULD BE A BLAST.
Thing is I also want to keep the z pretty stock it's only done 72,000 kms and I have owned it for 23 years so I decided to try to get the most out of the 2.8 as I could with some simple upgrades. I am 60 and planning on keeping this thing till I croak. Based on my experience with the wrangled getting back to factory drivability takes a great many tune attempts. Eventually I found an ex diablosport (Google them) tuned in the states and 25 revisions later it was good.
I don't want that with the z. A s54 transplant is my ideal goal. Not stock but still factory. They just getting rare and costly. We never got the M roadster here. Just the coupe. I could easily go Z4 M but I don't like the dash. To me it looks clunky compared with the Z3. Later model z4 addressed the issue with a much more attractive dash but I don't want to spend that much money. The 3 is also a much more raw beast with lower limits. In the z the car runs out of ability at the back before I run out of talent. The 4 is the other way around by a long way.
Sorry for war and peace. Second glass of chardonnay. Local of course!
- Joined
- Dec 8, 2011
- Points
- 145
I'm happy for any distractions. I'm in a cold warehouse, waiting for a guy who is now going to be an hour later than planned.
An S54 transplant is not a thing to take on unless you have deep pockets or a decent workshop. It's a totally different car if done properly.
Rear axle
Exhaust
Wiring loom
ECUs
Engine
Gearbox
Propshaft (?)
and probably a load else
Thought the GB was the same?
- Joined
- Dec 8, 2011
- Points
- 145
the same what?
- Joined
- Oct 19, 2014
- Points
- 174
- Model of Z
- 2.2i Sport
Suspect he means gearbox.
This ‘mountain’ comment made me chuckle.Where in the world? 5,500ft is over 1,000ft higher than our highest mountain
We came from South Africa many years ago and toured Scotland- we got to this ‘mountain’ called Ben Nevis and had to double check the map. All we could see was was a mound that could maybe qualify as a large hill in SA
- Joined
- Oct 19, 2014
- Points
- 174
- Model of Z
- 2.2i Sport
It's not all about size, you know.
- Joined
- Dec 8, 2011
- Points
- 145
Ahh, I was thinking GB = Great Britain
.Anyway, the gearboxes are different. S50 and S54 boxes are rated to 320Nm, the standard box is only rated to 310Nm.