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Side Draughting An Spi Throttle Body


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#31 sonscar

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Posted 21 August 2020 - 10:40 AM

I do not know for certain but I doubt that the Men's relies on the lambda at anything more than idle and cruise.It probably runs open loop off its map at acceleration and higher loads.There is much talk of the ECU "learning" and again I do not know for certain but I cannot see it doing so as there are not enough sensors.
The Siamese ports are a well documented problem and Mpi is sequential with large injectors to get the fuel in a smaller and smaller window.Two wideband sensors are the minimum to map properly.Have lots of fun,I know I did.Steve..

#32 Curley

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Posted 21 August 2020 - 02:12 PM

That's quite a summary there Wazzah! It's good to know there are like minded people on this forum who are not scared off by 'modern' engine management. I know people who think the MPI is not a real mini because they don't have an SU.... I'd be interested to hear your war stories Sonscar, anything tricks you want to share?

 

Having never owned a real SPI/MPI I can only go on what I'm told about MEMS. But looking at the documentation I understood the SPI system has no CAM signal at all. It's essentially adding half the fuel on each of the up strokes? However the SPI dizzy is an empty body and the shaft meaning it was trivial to convert over to use a hall effect sensor thus gaining a cam reference, unlocking sequential injection and sequential ignition.

 

I started out looking at the Elite 750 as I originally only wanted to run electronic ignition. But the decision to enter Libra class over Miglias means I can run EFI :) I went with the 1500 over the 1000 as it support 4D boost tables, multi-level engine protection, and multi stage nitrous; not necessarily things I wanted for this car but I figure the ECU & PDMs will come with me to the next project & the price difference at the time was negligible.

 

I've never had an issue with the wasted spark on my previous car, but that was running an OMEX 200, recharge times and heat were no a problem. But ditching the single or multi point TBs in favour of sequential injection is my ultimate goal. I had through a cross flow head would be the only way to do this but a pair of TBs on straight branch manifolds would give us 4 injectors. 4 injectors = 1 injector per cylinder so sequential injection should be possible??? Add a pair of wideband, 1 for the inner cylinder and the other for the outer cylinders (because outers will run leaner) and it should then be possible to do a proper fuel map??



#33 sonscar

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Posted 21 August 2020 - 06:41 PM

The problem with sequential is that there is a small window to inject in.As Rpm rises this gets smaller so injectors need to be large.Flow rate at idle with large injectors may be a problem leading to poor idle and emissions.I hardly dare to mention Megasquirt but their is a solution in their lineup.I have megasquirt one on my 1800 mgb and 3500 V8 mgb both running it for ten or more years.Efi is rewarding to fit and master but needs careful research and even more careful tuning.find a reliable guide and follow it exactly,it is easy to cause damage.Good luck,Steve..

#34 IronmanG

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Posted 22 August 2020 - 04:53 AM

Following with interest. Can you give a couple of recommendations for ECU.
Haltech I take it. What else. I am running 7 port. Dont want to do it on the cheap but value for money?

#35 sonscar

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Posted 22 August 2020 - 08:14 AM

From my limited experience the ECU is almost secondary.The tuning software interface is the most important.YOU or your tuners ability to understand and use it is the second most important.Forget everything you know about carbs and distributors and learn Efi specific tuning.A90% worn carb and dissy will still work but the ECU will only do what you tell it to do,make sure you educate it properly.Buy a book on Efi fitting and tuning and enjoy this new world.Steve..

#36 IronmanG

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Posted 22 August 2020 - 02:52 PM

THanks Steve.
I am putting all my trust in OZ so no problems there. My trust in the SC delta though after reading reviews is taking a hit and the after sales service apparently leaves something to be desired. I have already paid for it so I have to give it a chance. OZ I have no doubt will get it running, and running well, whether it keeps the program he puts in......
So a different ecu would be handy to have as backup. A second dyno day I can do without

#37 Wazzah

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Posted 06 October 2020 - 10:58 PM

So the engine is rebuilt and I've done 1000km with the side draught and 45mm SPI throttle body.

Motor is now 1310cc with a SW5 and big valve, ported head.

Ceramic coated LCB has reduced under bonnet temps and the throttle body is cool to the touch after a run.

I had fitted a wideband lambda and smartphone gauge but that just didn't work and was quickly ditched for a narrowband.

MEMS was a lot happier.

An adjustable fuel pressure regulator helps with the fine tuning.

Not much grunt under 2000 rpm but generates a lot more torque through the mid range making it a quick fun car in the traffic.

On this good torque pressure setting it runs out of fuel above 5000rpm.

Enriching the fuel by screwing down the regulator gives me 170kph in fourth but I feel there is more potential there.

I think the under 2000 stuff is tuning as well.

We all know that MEMS can reach it's limitations and if I was to guess my HP i'm around mid 80's.

Pre rebuild the side draught did run better with the standard throttle body.

From here I'm going to persevere with the sidey and have got an aftermarket ECU on the way to play with.

It has full wideband control and learning and can run a stepper motor.

It can also handle the weird 36-4 reluctor on my model.

The car is slow off the mark now and it will effect hillclimbs when our club racing starts back up.

If I can't tune this low down stuff and improve this I may have to revert to the smaller throttle body or go the larger TB on the SPI manifold and ditch the sidey.



#38 Wazzah

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Posted 06 October 2020 - 11:02 PM

The other thing is the car runs better on the 5-ES plugs as opposed to the 6-ES.



#39 Tones61

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Posted 07 October 2020 - 04:47 PM

How would an mpi run on a 45 dcoe and poss a no dizz set up,or will it be better on an elite ecu from aus,
Car has fast road spec head,lcb with lambda,rc40,k&n,med 1.5 rollers,med lightened Verto,
Any info appreciated,thanks

#40 Wazzah

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Posted 07 October 2020 - 08:03 PM

Hi Tones,

Personally think a 45 DCOE is a backward step.

Especially if your running MEMS for your ignition set up.

The MPI's have a 6150rpm rev limit so you still miss out on a lot of top end that the Weber could give you.

If I had an MPI i'd experiment with a couple of injection trumpets and chuck the manifold away to get a bit of air flow.

Given the way the injectors sequence it would be simply be a bolt off, bolt on, plug in scenario with a bit of work on the accelerator cable.

My JDM 99 SPI has the cam lobe and hole for the MPI cam sensor so I am pondering converting to MPI some stage down the track.

I'm building twin SPI throttle bodies on straight runners as a side project at the moment.

Just purchased an Elite 1000 which could run an MPI nicely as it can accept inputs from both cam and crank sensors.

There are no base maps for a mini available but I've written my own using the volumetric efficiency method.

I have a very good timing map which I developed during my SC Delta period and used the values in that map on my new ECU.

I'll write it up on the forum when I've got it sorted.



#41 Tones61

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Posted 08 October 2020 - 06:36 AM

Ok,many thanks wazzah,I will look into throttle bodies,with mems,or poss an elite also,I appreciate your in-depth write ups and info, thank you ??

Edited by Tones61, 08 October 2020 - 06:36 AM.


#42 Bobbins

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Posted 08 October 2020 - 08:13 AM

A twin SU setup converted to be throttle bodies running two injectors would be nice .....

#43 sonscar

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Posted 08 October 2020 - 09:31 AM

SU lookalike throttle bodies are available.Wallet bashing though.Steve..






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