my max onset of boost is 28psi which is where I have set the Snow to deliver its max.. onset starts at 14psi. I cant remember my jet size off hand. 
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DPJ's GTRS Eliminator Install and Development
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my max onset of boost is 28psi which is where I have set the Snow to deliver its max.. onset starts at 14psi. I cant remember my jet size off hand.
Interesting, Bill - I can't set mine to start higher than 8psi. (that's max on the controller)
Code:
a b c d e f g h i j
4680 15.98 145.39 16.84 198.73 1.37 0.92 17.76 209.57 1.44
5080 15.64 168.53 17.89 211.13 1.25 0.92 18.81 221.96 1.32
5480 16.32 182.47 20.14 237.65 1.30 0.92 21.06 248.49 1.36
5840 16.66 200.81 21.91 258.54 1.29 0.92 22.83 269.38 1.34
6240 15.98 208.39 22.46 264.97 1.27 0.92 23.37 275.81 1.32
6600 15.64 215.78 23.25 274.30 1.27 0.92 24.16 285.13 1.32
6920 14.96 216.22 23.31 275.09 1.27 0.92 24.23 285.93 1.32
7240 14.28 217.50 23.28 274.73 1.26 0.92 24.20 285.57 1.31
7480 13.94 219.69 23.48 277.08 1.26 0.92 24.40 287.92 1.31Column a is rpm
Column b is injector on time for 550cc inj
Column c is maf reading (maf is 1.32 times the area the ecu thinks it is)
Column d is fuel flow in g/s (see dpj's calc)
Column e is calculated airflow at 11.8:1 afr which is what it runs
Column f is e/c
Column g is methanol input as if it was petrol at 6:1 afr based on 300cc inj at 50:50 w:m and 0.9 density
Column h is petrol+meth (back calculated as if it was all petrol)
Column i is calculated airflow based on petrol and meth input
Column j is i over c
odd that its i/c is almost exactly 1.32 which is the same as the calculated maf scaling based on area of the maf i'm using over a cupra r maf which the modified stage 3 code thinks I'm running.
I love maths
...............
I love maths
Me too
Sorry John, I looked in briefly, I'll have to ponder what your saying tomorrow morning.(Were my figures right?)
One thing I've noticed dave is that you're running more airflow than me as your boost overshoots. Now I'm running 24-26psi at that point, so you have a fairly hefty uncontrolled overshoot of boost to about 30psi. Probably not the best idea
I'll give up puzzling over this for now
I've worked out that 6:1 is close to stoich for methanol at 6.4, but I can't quite work out how you get 0.92 g/s of methanol. (I think I've misunderstood you, I take it as 300cc w:m injected per min = 5cc/sec = 2.5cc of methanol = 1.98g/s )Apart from that, your figures make an impressively tight case.
It makes me more confused about what my methanol is doing - it's becoming more and more apparent that very little of it is being burned.
You mean around 4-5k rpm? My boost gauge seems reasonable accurate and it's showing about 28psi before it falls. What can I do to control it - should I be dropping the boost on my SPS3? If that's the case, should I dispense with experiments with the mbc and attempts to pull 2.5 mbar across the range? Are you running a boost controller, John?
Thanks for your interest.
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Dave
I did my numbers after 3 pints and a long day, but I'll try again 300cc at 0.9 density (meth=0.8 water=1) is 270g. 1/2 is methanol, so 135g, so 2.25g/s. Your 120g/min is actually the right way to calculate it, but hell I was drunk.
This requires 13.5g of air at stoich for meth which is enough to burn 0.93g of petrol at stoich.
0.92 or 0.93, I'm not saying it's 100% accurate, but near enough.
Your calc would give 0.88.
My boost is 24-26psi controlled on n75, but my n75 duty cycles are in the controllable range, so 60-80%. At boost onset, my n75 is only having to dial back from 100% to say 60% which will give a lot less overshoot than 100% back to 10%.
Your mbc is just a bleed valve, and should limit maximum boost, so remove the spike (to an extent), and should help you hold boost at the top end. You could just put a weaker spring in your actuator, or get an adjustable one.
I did my numbers after 3 pints and a long day, but I'll try again 300cc at 0.9 density (meth=0.8 water=1) is 270g. 1/2 is methanol, so 135g, so 2.25g/s. Your 120g/min is actually the right way to calculate it, but hell I was drunk.
This requires 13.5g of air at stoich for meth which is enough to burn 0.93g of petrol at stoich.
0.92 or 0.93, I'm not saying it's 100% accurate, but near enough.
Your calc would give 0.88.
My boost is 24-26psi controlled on n75, but my n75 duty cycles are in the controllable range, so 60-80%. At boost onset, my n75 is only having to dial back from 100% to say 60% which will give a lot less overshoot than 100% back to 10%.
Your mbc is just a bleed valve, and should limit maximum boost, so remove the spike (to an extent), and should help you hold boost at the top end. You could just put a weaker spring in your actuator, or get an adjustable one.
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Ahhhh - I see now! I hadn't thought about the last stage calculating petrol equivalent.
Cheers.
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ahhh, I see.
Wilko's made an interesting point (probably obvious to you John, but it's only just dawned on me.........) Once you've calculated the 'actual' flow of your maf, you can use the figure at each rpm reading to calculate boost. (by proportioning that figure to the weight of air that would flow through the engine at that rpm reading at standard atmospheric pressure.) Am I correct in saying you should then adjust the result by volumetric efficiency?
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Dave
You have to guess a bit at volumetric efficiency, but high 90's% in the mid range, where the cams are efficient, to low 80's at the top end where the head/cams aren't are not out of the ordinary.
I found the small port with standard cams had fixed airflow over 6200rpm for constant boost. In other words VE was dropping as fast as revs were rising, cancelling any extra airflow that the engine should be consuming as revs rise out.
VE will also drop as boost rises, as you're measuring pressure just before the inlet manifold. The pressure drop across the manifold and valve train will increase as flow(boost) increases.
In other words, VE will be better at 1 bar than at 1.5bar of boost.
250g/s seems to be about the max flow for the small port at 1.5bar boost. On my large port with cams, and inlet manifold, it is nearer to 300g/s at 1.5bar with a 7500rpm limit. This appears to continue to rise linearly, so more revs (and a larger turbo) would allow for more flow.
I think if you're going for a bigger turbo (>350hp) then a big port and cams will give efficiency (and longevity/safety gains), as will reducing pressure drop across the whole intake system.
You have to guess a bit at volumetric efficiency, but high 90's% in the mid range, where the cams are efficient, to low 80's at the top end where the head/cams aren't are not out of the ordinary.
I found the small port with standard cams had fixed airflow over 6200rpm for constant boost. In other words VE was dropping as fast as revs were rising, cancelling any extra airflow that the engine should be consuming as revs rise out.
VE will also drop as boost rises, as you're measuring pressure just before the inlet manifold. The pressure drop across the manifold and valve train will increase as flow(boost) increases.
In other words, VE will be better at 1 bar than at 1.5bar of boost.
250g/s seems to be about the max flow for the small port at 1.5bar boost. On my large port with cams, and inlet manifold, it is nearer to 300g/s at 1.5bar with a 7500rpm limit. This appears to continue to rise linearly, so more revs (and a larger turbo) would allow for more flow.
I think if you're going for a bigger turbo (>350hp) then a big port and cams will give efficiency (and longevity/safety gains), as will reducing pressure drop across the whole intake system.
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As I had the car with me today, I had a stop-start journey home while I kept adjusting the mbc.
I've managed to set it so that (on the gauge) it reliably and repeatably pulls to 23psi before settling back to 22psi. It might be in my mind, but it does feel smoother now.
I'll try and log it later, then I can fine tune the mbc.
I've managed to set it so that (on the gauge) it reliably and repeatably pulls to 23psi before settling back to 22psi. It might be in my mind, but it does feel smoother now.I'll try and log it later, then I can fine tune the mbc.
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It does feel fine, Phil. I'm embarrassed to say I'm not sure if the spool has changed - I'll have to check. I'm really pleased John pointed out the overboost, it does answer why the N75 was struggling to cope. I'm wondering now if it was responsible for some of the CFs, and if I now might be able to go back and advance the timing.......
I really feel I've made a step forward today.
more revs more power so long as your total system can flow it.. (inlet and exhaust)
had a good chat with CNC heads at autosports show with respect to big port head... shared some info with them, so they may relook at what possible from smallport on next setup, as largeport heads are not as readily available as smallports.. but the market for those who need heads which can flow that high is going to be very small here in the uk i think
had a good chat with CNC heads at autosports show with respect to big port head... shared some info with them, so they may relook at what possible from smallport on next setup, as largeport heads are not as readily available as smallports.. but the market for those who need heads which can flow that high is going to be very small here in the uk i think
Wooo Hoooo!
Tweaking out the overboost has virtually removed the dip in my airflow. I've now done runs at T9 HB9 with no correction factors. It looks like I can now dial in some timing.
Do I pull boost down a fraction and chase timing now?
Tweaking out the overboost has virtually removed the dip in my airflow. I've now done runs at T9 HB9 with no correction factors. It looks like I can now dial in some timing.
Code:
Saturday 12 January 2008
06A 906 032 HN 1.8L R4/5VT 0002
Group A: '002 Group B: '020
Idle speed Engine load Inj. period Air mass in Idle Stabilization Idle Stabilization Idle Stabilization Idle Stabilization
700-820 rpm 15-25% 2.0 - 4.0 ms 2.0-4.5 g/s
/min % ms g/s CF CF CF CF
3520 135.3 10.54 96.47 0 0 0 0
3760 161.7 12.92 120.28 0 0 0 0
4040 188 14.96 149.67 0 0 0 0
4280 191.7 15.98 173.67 0 0 0 0
4560 191.7 16.32 186.81 0 0 0 0
4800 191.7 16.66 194.58 0 0 0 0
5040 191.7 16.32 198.81 0 0 0 0
5320 191.7 15.98 205.25 0 0 0 0
5560 191.7 15.3 205.69 0 0 0 0
5720 189.5 14.96 203.78 0 0 0 0
5920 188 14.96 208.42 0 0 0 0
6120 189.5 14.96 223.58 0 0 0 0
6280 182 14.28 216.56 0 0 0 0
6440 178.9 13.94 223.67 0 0 0 0
6640 173.7 13.6 219.69 0 0 0 0
6800 168.4 13.26 219.69 0 0 0 0
6920 163.2 12.58 221.44 0 0 0 0
7000 162.4 12.92 218.83 0 0 0 0
7160 158.6 12.92 215.53 0 0 0 0
7200 157.1 12.92 224.11 0 0 0 0Do I pull boost down a fraction and chase timing now?
Code:
Group A: '002 '031
rpm Inj. Air Lambda Lambda Fuel Fuel A/F Air Scaling
/min ms g/s Actual Target litres Weight Actual
g/s g/s
3600 10.2 72.06 0.844 0.649 0.0112 8.27 12.41 102.59 1.42
3720 12.58 108.14 0.75 0.735 0.0143 10.54 11.03 116.19 1.07
3880 14.28 128.14 0.75 0.782 0.0169 12.48 11.03 137.56 1.07
4120 15.64 156.22 0.75 0.797 0.0197 14.51 11.03 159.98 1.02
4400 16.32 180.92 0.789 0.797 0.0219 16.17 11.60 187.55 1.04
4640 16.66 188.42 0.797 0.797 0.0236 17.41 11.72 203.95 1.08
4880 16.32 201.44 0.805 0.805 0.0243 17.93 11.83 212.23 1.05
5120 15.98 198.44 0.805 0.805 0.0250 18.42 11.83 218.03 1.10
5360 15.64 204.39 0.774 0.805 0.0256 18.88 11.38 214.79 1.05
5600 15.3 205.08 0.805 0.805 0.0262 19.29 11.83 228.32 1.11
5800 14.62 205.39 0.797 0.805 0.0259 19.10 11.72 223.72 1.09
6040 14.28 219.03 0.797 0.805 0.0264 19.42 11.72 227.56 1.04
6240 14.28 219.36 0.782 0.805 0.0272 20.07 11.50 230.67 1.05
6440 13.94 220.78 0.782 0.805 0.0274 20.22 11.50 232.40 1.05
6560 13.94 223.22 0.789 0.805 0.0279 20.59 11.60 238.85 1.07
6720 13.6 222.53 0.797 0.805 0.0279 20.58 11.72 241.12 1.08
6880 12.92 217.53 0.789 0.805 0.0272 20.02 11.60 232.17 1.07
7000 12.58 212.78 0.782 0.805 0.0269 19.83 11.50 227.96 1.07
7120 14.28 220.11 0.797 0.805 0.0311 22.90 11.72 268.25 1.22
7200 13.26 217.53 0.75 0.805 0.0292 21.50 11.03 237.03 1.09
7200 13.94 222.36 0.75 0.805 0.0307 22.60 11.03 249.19 1.12
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Might as well leave the boost and run some more timing dave. Looks pretty good to my untrained eye.
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