EFI Testing - Dyno Day 6: 1.5:1 Ratio rockers
Turbo Mini Forums

Edited by Graham T on 8th Jul, 2019.

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also a longer column of moving air means more weight so greater inertial ramming.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

If something is worth doing, it's worth doing half of.

this is very clever.

Team www.sheepspeed.com Racing

Thanks John

and Jim, it’ll be clever if it actually works…




A Little more progress.


Finally got the motor mounted and tested the assembly







It moves…

https://youtu.be/wIUezOf3HT8

But not enough torque or speed. As expected.
Also, this is without the lipseal installed, so I am not sure what difference that will make.

Trying to figure out how far it might need to move, so that I know how fast it needs to move, if I add up all the way points in my previous table back on page 7, I’m getting 680mm of movement to run through the rev range.
If it needs to truly move around 680mm total to get from 2250 to 6250RPM, then I would need a motor capable of rotating 85 times in the amount of time necessary to accelerate the engine from 2250 up to 6000RPM.
Each rotation of the lead screw gives a linear movement of 8mm.
(BTW, The leadscew, leadnut and support bearing were sold as a 3D printer repair kit on amazon)


Last night I recorded around 5 seconds to accelerate from 2000RPM to 6000RPM in second gear, with 8PSI boost.

So if I use that 5 seconds as the target, I need to rotate the leadscrew 17 times per second, or at 1020RPM.

The maximum almost reliable speed I have gotten from the existing Stepper motor so far is 4.5 Turns per second or 270 RPM.

The trouble with Stepper motors is that they lose their torque very quickly as RPM increases, so above 270RPM, this current stepper motor either stalls or misses steps.

I think I need to look at the next power rating up, which will give more torque at higher rev’s, but then the best NEMA 17 I have found so far still only shows a maximum 512RPM (8.5revs per second) for reliable operation, but holding torque is 65Ncm, compared to the current 40Ncm, which should make a big difference.
It is either that or a Go up a size to the NEMA 23, but that's more hassle and a lot more weight.


These stepper motors are cheap enough, so I will try the higher hold torque rated NEMA 17 first and then go from there.


Much more work to do, but at least I’m making some progress…

’77 Clubman build thread
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=618189

Siamese 5 port EFI testing
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=611675

Im supprised its 85 turns of the lead screw to go from short to long.

somthing to watch out for, we have used steppers here at work, and ran into heat issues with them due to the over;ap timings on the steps, basically the stepper fighting itself. that wias with a generic stepper friver pcb. we had to do our own and fudge the code to stop it.

Ironically Ive got a cheap 120 quid 3d printer here that uses the same motors with no problems,

could you gear the motor to the shaft then use multiple motors ?

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

very clever.

Could you use the boost to push it out, and aspring to return, use PWM to control how far it goes and a linier encoder to see its current position?

Team www.sheepspeed.com Racing

’77 Clubman build thread
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=618189

Siamese 5 port EFI testing
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=611675

if the stepper isnt fast enough, may I recommend you do what BMW do for their variable valve lift and just have a good ol' brushed DC motor, controlled by an h-bridge, with position feedback.

Very fast, and torqey.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Thanks Denis,
yes, that is also a consideration.
I have found a few 12V geared motors with encoders so far. They will work out a fair amount more expensive than a stepper motor, mainly due to the current that the driver boards would need to handle, but I am now thinking using a stepper motor is probably not the way to go.

I also started looking at continuous rotation servo’s as another option.

Also, I now think I need to add a stop sensor/ switch regardless of motor type. Something to set a home position by.
With the current stepper motor, returning it to a position for "home" on start really makes a lot of noise once it actually hits a dead stop.

With a DC motor I will definitely need to sense “home”.

’77 Clubman build thread
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=618189

Siamese 5 port EFI testing
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=611675

So, todays offering:

Another Dyno session, this time to measure differences with the 4 deg change in Cam timing.
The original timing was at 106 Deg, this was changed to 110 Deg when I sorted out the Cylinder head gasket.




176.5BHP @5570BHP and 203KPa (~14.7PSI)
190 Lbs/ft Torque @4430RPM and 213KPa (~16PSI)



Compared to the best ~15PSI run back in Feb that’s a good increase in peak power, but a substantial loss in peak Torque.







As expected, you can see around a 500RPM shift of the whole power curve.


I’ve still more data to work through yet, so this is just initial results.

’77 Clubman build thread
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=618189

Siamese 5 port EFI testing
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atthss interesting, less difference to the overall shape than i expected.

If I’m honest Joe, I was really not sure how to expect the shape to look.


I am thinking though, that peak BHP was not as high as it could have been.

I had hoped peak torque might have been fractionally higher based on the MAP at peak torque, but peak BHP, I think, could have been higher.






And the reason I say that is because we had a fuel fuelling issues, due to some historic settings.




What we have found over previous Dyno sessions is that this Engine seems to like around 12.5 to 13 AFR on peak power.

The below shows AFR Comparisons between the Jul -52 run and the previous Feb -41 run.





Ignoring the rich state at around 3200RPM (which I have to adjust), you can see from ~3750 RPM upwards that fuelling is gradually getting richer and richer.
After several runs decreasing fuelling in those area’s in the VE table and seemingly getting nowhere, we took a more in depth look at other settings.
This was mainly prompted by the high MAT temps we were seeing.

What we found was the MAT correction table was populated with 15% enrichment at 35 Deg C up to 20% at 45 Deg C

Oops!

This was a throwback to my original staged injector manifold and the turbo on the log type manifold.


It used to be that after parking up, I had massive heat soak in the plenum and was getting some nasty lean fuelling until it all cooled down, hence I found that by using “non linear MAT correction” I could get rid of those lean conditions.
But because we have never had the inlet temps that high on the dyno before now or even on the road since I changed to the remote turbo, it got missed.

On Wednesday, it was hot and inlet temps were getting pretty high.





(Note to self to change the logging settings for temperature from 0 decimal points to 1 decimal point…)


So as soon as the inlet temperature was rising above 30 Deg, the non linear MAT correction was adding fuel.
From around 3750RPM it was starting to add fuel based on the Non Linear MAT correction table.
By the time the engine had got to 4700RPM there was an extra 15% added and then by the time it was at 5600RPM that was 20%.

This would explain why we were not able to reduce the AFR's off of the VE table.
We were taking fuel out of the VE table cells, but due to the heat building up in general under the bonnet, each run was building the inlet temps so partially countering the reductions we had made on the VE table..

We did not find this “small issue” until fairly late in the session, so I opted to leave those settings, just to try to get comparable data with the earlier runs in the session.



From previous Dyno sessions, notably last August’s session, whilst trying out different AFR’s, there was around 8BHP change at peak power over a 1 AFR change.
Ultimately at around 11.5 AFR the engine was producing 8BHP less than at 12.5 AFR.

Hence my above “Expected Output” plot shows an additional 10 or 11 BHP at peak power to what we actually recorded, adjusted for the richer condition.


Regardless, I am extremely happy with the results we got from the session and that we managed to get a good increase in peak power – at least I am no longer stuck in the 160’s.

I am also chuffed with the fact that I resisted the urge to change 60% boost duty to 85% boost duty – Mainly due to Robert threatening to take the laptop away if I kept tweaking the boost duty table.



But look what happened to my SOT:




More to follow...

Edited by Graham T on 19th Jul, 2019.

’77 Clubman build thread
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=618189

Siamese 5 port EFI testing
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=611675

This is the best thread on turbominis in a long time. Keep the updates coming.

Phil.

WWW.TURBO-MINI.COM

It was a great day of research , and changing the cam timing netted a increase of 18 bhp and with a better mixture , possibly way more , all for no financial cost , just moving the cam around the sprocket .


as i said to graham , this how the spud is setup , i knew i would have no grip low down , so deliberately lowered trq , to gain bhp ,and be able to use the power when i would have grip ...although a huge wheelspin at 80 mph on my last drag race was a bit of a give away that there are limits even then lol.

something else to born in mind graham was our ign changes , also adding to the bhp increase for run 52 ...to get a more direct comparison we need to use a run with the same timing as 41 ?

Edited by robert on 20th Jul, 2019.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

’77 Clubman build thread
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=618189

Siamese 5 port EFI testing
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=611675

Before I move on to working through the other runs in the session, I was interested to try to understand that peak in the SOT plot at around the 2600RPM range.

This is a cleaned up version of the SOT plot for run -52







Looking at the other data, I can see no real reason why the peak should be there.


I would have expected to see something like this, maybe…:







To get the above SOT without that peak, the actual BHP readings would have needed to look like this






So around 4BHP less than recorded.


Now, whether this is right or wrong I am not sure, but as said, I cannot really see anything that should cause such a rise in the SOT, then for it to drop down again.



But what I did find while looking at all the data was this:







Might be just co-incidence, but it would be damn good if that SOT peak was due to the runner length.

Interestingly, you can also see a small peak 200RPM further down the rev's on the Feb -41 run.

’77 Clubman build thread
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=618189

Siamese 5 port EFI testing
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=611675

While your messing with motors and stuff... Maybe you could add a sprung timing chain /belt tensioner, and a movable one the other side so you can advance/ retard the cam on the fly....

’77 Clubman build thread
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=618189

Siamese 5 port EFI testing
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=611675

Excellent stuff!!

In the 13's at last!.. Just

Graham i think its worth putting up a sot with the sot's from my car,jims 16v and anything else that was high , so we can see how well you are doing with this .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Nice!

’77 Clubman build thread
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=618189

Siamese 5 port EFI testing
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=611675

When I went to Roberts on Wednesday I had done a small amount of road tuning to get the boost sorted and get somewhere near with fuel mixture.
I had backed off the wastegate preload in order to reduce the base boost, just because I was worried about the repairs to the plenum holding out and also, I was seeing leaner Mixture than I had before I changed the cam timing.
The only way to get up around 6K Rpm on the road was in 3rd gear, which was getting more and more hairy the higher the boost was raised.
Finally I decided just to leave it at around 12.5PSI and do the rest on the dyno.


So here are the graphs for each run:

Run 45

This was straight off the road, so nothing changed from my settings






Peak BHP 160.5 @5570RPM, 12.2PSI
Peak Torque 176 Lbs/ft @ 4067RPM, 13.1PSI




Run 46

Increased Boost Duty by 5%.







Peak BHP 162 @5388RPM, 12.6PSI
Peak Torque 176.5 Lbs/ft @ 4300RPM, 13.6PSI


Engine was still in warm up, so around 8% fuel was being added, which we thought was why the mixture was so rich.



Run 47

No changes made, but made sure warm up enrichment was not on.







Peak BHP 164 @5414RPM, 12.7PSI
Peak Torque 177 Lbs/ft @ 4300RPM, 13.9PSI



Run 48

Added 5% Boost duty.
Reduced Fuelling by 2% at 4000RPM and up.







Peak BHP 171 @5285RPM, 14.2PSI
Peak Torque 188 Lbs/ft @ 4223RPM, 14.9PSI



Run 49

Reduced Fuelling by a further 2% at 4000RPM and up.
Reduced boost duty by 2% at 4000RPM
Increased boot duty by 1% at 4700RPM







Peak BHP 172 @5362RPM, 14.6PSI
Peak Torque 186 Lbs/ft @ 4456RPM, 15.2PSI



Run 50

Reduced Fuelling by a further 2% at 4000RPM and up.







Peak BHP 172 @5181RPM, 14.3PSI
Peak Torque 187 Lbs/ft @ 4378RPM, 15.6PSI


At this point it was obvious there was something wrong with the settings, for the AFR’s not to have changed after taking 6% out of the fuel VE table, which is when we found the Non Linear MAT correction settings.

Rather than change the fuelling that late into the session, Robert felt there was not enough Ignition advance at peak power, so we concentrated on that instead.
So first off Ignition advance was reduced to get an idea on how the engine would react.



Run 51

Whole Ignition timing table reduced by 2 Deg.








Peak BHP 173 @5362RPM, 14.9PSI
Peak Torque 185 Lbs/ft @ 4352RPM, 16.1PSI


Overall this lost us power above 4250RPM, but gain power below 4250RPM.









So the ignition map was changed to add 2 deg back in above 4250RPM and then a further 1 Deg advance on top of that.

Which is where we ended the session, on run 52








When I next get a chance, I will take one of the runs before the igntion timing was altered to compare with Feb's Run -41.

Edited by Graham T on 22nd Jul, 2019.

’77 Clubman build thread
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=618189

Siamese 5 port EFI testing
http://www.turbominis.co.uk/forums/index.php?p=vt&tid=611675