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

As previously mentioned, I have mostly been running on the road at around 142KPA (6PSI) since installing the new “X7” manifold.
Now that I am up at 13PSI and over on the road, things are getting a bit hairy.


I ran on the road at 16PSI for a while after the very first Dyno session at SRE and accepted that there was a certain amount of “manageable” torque steer. But that was nothing like the torque steer I now have with the remote Turbo and the “X7” manifold.

OK, this is not massive boost, but the torque steer is horrendous.

Currently I am working thorough trying to reduce Torques steer, or I was until the weather started to turn in the autumn.

So far I have installed adjustable bottom arms and tie bars and tried to set corner weights as best I can.


Homemade corner weight tool:








According to my measuring tool I am now within 15PSI side to side front and back. Which is better that the original measurements taken of:

Front NS = 660 PSI Front OS = 870 PSI
Rear NS = 680 PSI Rear OS = 300 PSI

Current geometry settings are -1.5 Deg Camber, 5 Deg Caster (I think) and 0mm toe.


I’ve still got a little more tweaking to because the caster was slightly different side to side, but it is at least now back into the realms of manageable with regard to torque steer.

The intention is also to temporarily swap the wheels for some standard R12” Mini wheels as a test to see if the ET -7 offset of those I have on there currently is a big part of the issue.

’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

The next thing that I found to play with was the exhaust system.


After I got the car more controllable, I noticed in the logs that up around 4500RPM, the back pressure (post turbo) was up around 5PSI, which seemed a bit high.

The first thing to change was the Motorbike silencer that I have been using since I put the car on the road, which after looking at it properly was pretty obviously restrictive.
What I had thought was a massive straight through bore…







… actually was not:








So this got replaced with a 2.5” silencer (Jetex).







Not only has this made the car much, much quieter, but it has reduced back pressure by 2 PSI. But still, that’s 3PSI back pressure left in the system.

In hindsight I could probably have gone for the slightly shorter version of this silencer.




The next step was perhaps a bit overkill - a complete new exhaust system all the way through.
































Not easy to fit in!



I had to oval the downpipe between the drive shaft and subframe, plus the downpipe had to be in 2 pieces to be able to get it in and out.


So that’s 2.5” OD straight through, or the equivalent X-sectional area on the oval section.



For the turbo Exit elbow, I have tried to increase the volume and make a sort of expansion chamber, in hope the exhaust gas might initially escape the turbine housing a little quicker and give slightly faster spool up.

This elbow should be just over 1 1/2 times the overall volume that a 2.5” mandrel bend would have given.


Final configuration under the bonnet.









The lambda sensor sample chambers had to have shorter stubs into the down pipe than I would have liked, but I think it should be OK.
Also, I have shortened the sample chamber feed pipes from the exhaust runners. This was done to try to increase the exhaust gas temperature in the sample chambers. The max temperature I had read before these changes was ~310Deg C.
In the only drive out I have had with this new exhaust system, the sample temperatures are slightly higher, with a max of 380 Deg C.



This all appears to have had a good affect with a further 1.5PSI reduction in exhaust back pressure and…






…Higher boost at lower rev’s, so it would appear I did manage to improve the turbo spool, but at the same time screwing up the Boost control settings.

Below shows Mass air flow comparisons, just to confirm the Engine was getting more air into the cylinders, not just producing extra boost for no gains.







The Red trace, “X7 MAF 19th Oct – Corrected for air temp offset” was just an attempt to illustrate how MAF would have been affected by the 10Deg difference in air temperature at the air filter between the October run and this latest run in January.



I have a new air filter which I am hoping I can mount further from the MAF sensor to try to clean up the MAF output. The current air filter is directly on the end of the MAF and I wonder if this is causing air turbulence, hence the very spiky MAF trace.



Settings wise, nothing has been changed between the last set of logs on 19th October and this most recent set of logs. Also, nothing has been physical altered on the Inlet side.


Obviously as said, I have only had one run out with it, so yet more testing and logging to do, but the changes in exhaust system appear to have made a significant difference.

’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 work graham.... well done .

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

loving this.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Great stuff. On the torque steer have you gone to rose jointed arms? As any compliance in bushes can magnify the effects of torque steer.

Fantastic details. This is good stuff.

Thanks for the positive feedback gents.

Edited by Graham T on 30th Jan, 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

Well, as the weather turned out nice over the last couple of days I decided on impulse to get back on the Dyno to see what changes, if any, the new exhaust and change in wastegate actuator made before I start making yet more changes.

So yesterday I toodled on back up to Oxfordshire.


On the whole, I think a very successful couple of hours and it looks like the changes gave me a little more…




161.5BHP @4995RPM and 13.6PSI
191.1Lbs/ft @3847 RPM and 12.2PSI



Compared to the last run -36 on the Dyno in Sept 2018…


166BHP@5331 RPM and 14.1 PSI
171Lbs/ft @4471 RPM and 11.6 PSI






I still have not got complete control of boost yet, but it looks better.


I’m only just starting to go through the data, so more to come.

’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

Thats a truly great result; well worth the efforts!

Dazed and Confused....

Now, the above looked good, but right at the end of the session a kind of red mist descend on me and I felt the need to progress past ~160 BHP, so I suggested to Robert maybe we could turn up the boost Fractionally for the last 15 minutes

So, the above run (-41) was with boost control set at 100% right up to 3250RPM, then dropping to 61% at 3570 and slightly downward to 58% at 5500RPM

Knowing that we had had so much problem with getting the boost rise on the boost controller previously, and the fact it has always been like this right through from my very first Dyno session with SRE, I decided the best course of action was to half the difference between 100% and the current setting, so 85% sounded good, this in my mind was going to give me around 17 – 18 PSI peak boost.

What follows is painful in the extreme!!!

First run with this new boost duty, this was run 43:


https://youtu.be/1A_j0Dn5vEM





It looks like the first “pop” was at the point that the 18PSI overboost protection cut in.

The Log file shows the point where the overboost protection cut in with fuel cut and massive lean out.





In hindsight, it would probably had been better if I had NOT had over boost protection set to Spark AND fuel cut.

At this point in the session, the decision making processor had seriously overheated and had temporarily gone into limp home mode.

Choices…

1) Turn off overboost protection
2) Reduce Boost duty cycle

Obvious choice right?

Turn off all the safety features!




https://youtu.be/XO3j6-XqdJs






Apparently the wrong choice.







Well, that did not work out so well…



Regardless, how did that do power wise?



Well….

For run 43







152.3BHP @3900RPM and 12.8PSI
205Lbs/ft @3900 RPM and 12.8PSI


And for run 44





174.8BHP @4118RPM and 18.3 PSI
229.8Lbs/ft @3941 RPM and 15.7PSI




I still have a load of data to get through again, but for now, the carnage…

Just from initial inspection at Robert’s, the head gasket is definitely blown in the end at Number 4, we could see the coolant bubbling just above the core plug.
The engine runs perfectly well though, so there is a hope that it is not wrecked completely.

I very gently drove home, boost controller set to 0%, right foot very light and radiator fan on permanently.
In traffic the coolant temp crept up to 77 Deg C, oil temps stayed between 57 Deg – 67 Deg C, no loss in oil pressure at any point.
When I got back and let it cool a little, the header tank was 50% full.
No oil smoke at all either.



I think the head gasket blowing might not have been the only thing that went wrong.
I’m not sure and I do not have the experience to say 100%, but I wonder whether the gasket actually went on the first high boost run (43), as a result of the overboost cutting in and making it massively lean?


On the second high boost run (44), I am tempted to suggest that my Plenum fractured/ popped.
I have in all honestly been waiting for that to happen.
My MS2 has a MAP sensor with a max pressure rating of 250Kpa (21.6PSI) hence that’s the max on the above graphs, but Robert’s logging shows it maxed out at 23PSI.

I have already had to wrap the plenum with a Carbon Fibre bandage after it crack back in August last year.
The 1.2mm Aluminium it is made from flex’s massively with vacuum and pressure, so I wonder if it just gave up finally.

And the reason why I think it might have fractured is the fact that it was ticking over at between 1600 and 1800 RPM every time I had to stop at lights or junctions.
Normal tick over is between 950 – 1040 RPM.
On the drive home there was no sign of the outer cylinders running lean.
I have not actually had time to go and investigate any further today and that will have to wait until sometime mid-week, but it’s just a thought…



Obviously now the head is to come off, so I have more to think about:
Bigger exhaust valves?
Maybe a change in Cam, or at least a change in cam timing to try to get the power a bit further up the rev range.
Fitting of ARP head studs I guess
New decision processor for the owner.


It’s a bit of a setback that’s for sure, but I’m still pleased with the results as a whole, and I still have time to get it back together before the weather picks up enough to be out enjoying it.

’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

That 230 lbs/ft on 17 psi or whatever it was is just incredible .

well done for the positive attitude , and i must take part of the blame being focussed on the bhp needle to spot any detonation.. the moment it spun above 20 psi i backed off but was just a few 10th of a second too late ....the rate of boost rise was phenomenal.

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

So, it appears that the Plenum did split…






This is just outside of the area that I had previously bandaged with Carbon Fibre.

It looks like it ballooned and is about 4mm high than it was. Lots of fibreglass dust where it was rubbing on the bonnet coming back from Roberts.

’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

thats a big crack !

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

Yes, it looks like a fairly large crack in the plenum, but I’ve not cleaned it down properly yet to see what has actually happened to it and to what extent.



Instead I decided to get it over with and pull the engine apart.
























I guess my previous question, which I removed in an earlier post, regarding Exhaust valves is pointless asking now – It was going to be along the lines of “are there any down sides to putting Bigger exhaust valves in”.





No 4 Piston:










I noticed this on Piston Number 1









The red ring shows what looks like a dig mark in the piston.
The Yellow ring looks almost like a crack…

’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

looks like the head lifted due to not enough clamping graham .

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

Ok, thanks Robert.
so ARP head studs it is.
Everything ordered now to put it back together, including some offset woodruff keys for the cam to see if we can improve the top end slightly.
Hopefully it will be back up and running by the end of the coming weekend.

Until then, a little more data analysis.

This is run 40, the third run from Last Friday.






Nothing too excitingly different from the other runs, other than Robert used his data from this run to Calculate the State Of Tune of my Engine.

Information on State of Tune is near the bottom of page 3 on this very old thread.
http://www.turbominis.co.uk/forums/index.p...tid=324193&fr=0




I’d asked Robert if he could confirm the figures I had calculated as the S.O.T for my engine, because I did not believe I had it correct.

I just want some sort bench mark on how well it is performing.


So he sent me this:







Here are my previous:






My SOT traces for Feb read slightly higher than Roberts, only due to the fact I think that the MS2 is reading 1 PSI higher than Roberts logging equipment at Peak boost.



This last Graph, I’m not 100% sure it is correct…






But I thought it might be interesting to try to map the recorded Pressure ratio and Mass air flow against the GT1752 Compressor map.

Edited by Graham T on 26th Feb, 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

Interesting that the main gasket failure mode (where the fire ring was deformed outwards) is where the bulk gasket material is weakened by a relatively large un-supported hole.
And ironically, I'm 99% certain, that hole is only there so the same gasket can be used on the Cooper "S" type 11 stud heads.
Maybe the 11 stud conversion is actually worthwhile, in the past I've always thought it to be a waste of time but that's on the basis that most of the gasket failures I've seen have been between Nos 2 and 3 cylinders, not there.
But some extra clamping at that exact location might have prevented the failure, even if just by negating the weakness in the gasket material that the hole creates because I doubt there is a version of the gasket without the hole ???

Schrödinger's cat - so which one am I ???

Well, I have an 11 Stud ARP set on the way, so I guess I might as well convert it to 11 Stud while it is all in pieces.

A quick search on this forum suggests the conversion is not too difficult if I am careful...

It seems the most critical part is not to drill too deep into the block for the extra stud at No 1 cylinder end.

’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

good work big boy , maybe a steel tube welded to a plate you can bolt to the deck , and then drill down the tube to keep it square ?

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

I was reading through some of the Threads I found yesterday on the subject and I think it was Wil_H that posted that he drilled the head first, then used the head bolted back on the block as a guide to keep the drill in line.


When I read that, it made my mind up that actually, the job was not as scary as I first thought.

’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

We did it decades ago to another engineer's Mini back when I was in charge of the mechanical workshops at Bradwell - so had the benefit of some industrial size pillar drills.
Head first using a template taken from a genuine "S" head then machined a bit of brass rod into a sleeve with the OD of the hole in the head and the ID of the tapping drill so, with the head bolted on it self centred the tapping size drill.
Then, with the head back off, held the tap in the pillar drill to keep it vertical and rotated the chuck by hand to do the tapping.
That's probably a bit OTT but we had the equipment at hand, so used it.

That was a pre-Aplus block and we didn't break through (maybe the older blocks are thicker there?) but I've read of people just using thread sealer (loctite) if they do, providing it's additional studs and nuts in the ARP kit and not two bolts.

Also, I might be getting confused, but I think I read somewhere one of the conversion kits uses a smaller diameter stud at the thermostat end (to reduce the risk of it breaking through) ???

Schrödinger's cat - so which one am I ???

Some excellent results. Thanks for sharing.

Great to see the long intake runners and LCB style turbo manifold doing a great job in improving VE.



Your runner length of about 450mm is giving you peak torque/SOT at around 4500rpm as I would expect.

If you wanted to flatten and increase your torque/SOT at higher revs, then a slightly shorter runner length would do that.

Starting to feel inclined to do some work on mine now :)

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

’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

on the ARP kits I have used yep they are all the same diameter, (5/16?)