Full Engine Management. Twin plug, ITB. EFI

[SeanP]

Think out loud here.

Having got the green meanie on the road and running. Kinda semi happy with it and having some thoughts.

The car is a 1969 912 shell with a 911 engine.

The engine is a 2.2e (counter weighted crank, e heads refurbished etc),with Solex cams running Weber carbs. The barrels and pistons were not in the best condition when i built the engine, (the engine came inboxes with an unknown history so was put together to

A. Ensure it was complete.
B. Make it run and use it. So the barrels were honed to clean them up, which has put them on the large side of tolerance for piston/barrel clearance and ring gaps.

I have purchased a set of new barrels and JE 86mm pistons with a 10.5 compression ratio.

My thoughts are to progressively upgrade the engine still keeping the short stroke crank etc as there is just something about them.

Twin pug the heads and run a crankfire ignition system running two sets of coils from an ECU configured as a lost spark system. Keep the carbs on the car and getting running/run in. Speeduino or Megasquirt for the ECU.

Stage 2 is to build an EFI system using bike throttle bodies replacing the webers. From what I have read Triumph ITB’s seem to be popular in Porsche conversions. Reading the internet it seems that PMO and and Jenvey make 40mm throttle bodies and early Triumph seem to be around 40mm. The Triumph throttle bodies seem to be very affordable compared to the PMO/Jenvey offerings. I know that the linkages etc will need work, but that is part of the fun!

Does anyone have any experience of any of this or am I talking complete nonsense?

[KS]

You need to talk to impmad on here - he's the man with the experience in all this!

[impmad2000]

If you are on the DDK get together feel free to quiz me about my Targa. 2.2T Triumph ITBs crank fire ignition.

[impmad2000]

[911hillclimber]

I have battled through this game in a different manner, the expensive one which worked out well in the end, but was in places very hard going due to using suppliers in the USA.

My engine is a 3.2 flat 6 with the following:
10.5:1 CR, carrillo rods and hardware, Kent Cams GE60 grind cams, stock heads but twin plugged.
PMO carbs, crank fire ignition.

The engine was built to tolerate 8500/9000 rpm on 99 octane.

I chose a Clewett twin plug ignition kit, in part very good, but with a poor heart/ECU.
After a lot of grief and a lot of money got it all to work with help from 3 x DDK helpers.

The negative was all about the Clewett system and their designer/manufacturer.

You will find it very hard to find an ECU system in the UK to fire twin plugs, and i was not ready to fight electronics but Tim's solution works (on twin plugs?)

My experiences are:
Do not buy from the USA
Buy from UK sources
A lot of specialists of components here know little about flat 6 Porsches and twin plugging them esp on a budget. Tim's approach could be just the ticket for you.

Anyway, it all worked out well, 100 bhp / litre which was the aim and £10,000 in parts, 6K spent in the USA.

The engine was DIY build.

[911hillclimber]

double post, sorry.

[RobFrost]

You might want to take a look at Henry Schmidt's reply to my post on Pelican. Until his reply, I was planning on using this piston crank combination.

https://forums.pelicanparts.com/showthr ... ?t=1164175

That doesn't mean I've changed my mind yet but he knows a bit about building these engines so it's definitely making me want to get a few more data points.



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[SeanP]

You might want to take a look at Henry Schmidt's reply to my post on Pelican. Until his reply, I was planning on using this piston crank combination.

https://forums.pelicanparts.com/showthr ... ?t=1164175

That doesn't mean I've changed my mind yet but he knows a bit about building these engines so it's definitely making me want to get a few more data points.



Sent from my SM-S918B using Tapatalk

Read that.
The compression ratio advertised is calculated and is generally lower in the real world? It would be a case of building and measuring/calculating and machining if required. The 2.2 911s had a compression ratio of 9.8:1 from the factory the JE pistons only raise that by 0.7 points. Modern engines are running a lot higher compression and using lower grade fuel due to modern electronics controlling them hence the ECU to control the timing/spark in the first instance and once that is running reliably adding the EFI.
Also I am thinking of twin plugging due to piston crown and head shape. If I could configure the ECU to twin spark with a delay between the spark of 400 milli seconds it may negate the twin plug ignition
EFI with ECU and all the sensors that go with it means that the ignition and fuel ratio is calculated/controlled in real time in three dimensions and constantly varying dependant on emissions/engine speed/throttle position/air temperature/manifold air pressure/atmospheric pressure.

I could also add knock sensors to the engine to protect it further. It’s not like an MFI setup where you have a space cam and atmospheric pressure to control the mixture. This is modern electronics controlling in real time.

The ECU will handle the twin plug configuration easily running wasted spark across 2No. 6 plug coils with drivers as the coils are independently powered with only a control signal from the ECU.

Another thought I am having is to independently monitor the two banks of cylinders with sensors in the exhaust, but at the moment that is a little advanced as I may need to add CANBUS into the mix, and it may just be not required

But this is why I started this thread to get others views/experiences.

[SeanP]

I have battled through this game in a different manner, the expensive one which worked out well in the end, but was in places very hard going due to using suppliers in the USA.

My engine is a 3.2 flat 6 with the following:
10.5:1 CR, carrillo rods and hardware, Kent Cams GE60 grind cams, stock heads but twin plugged.
PMO carbs, crank fire ignition.

The engine was built to tolerate 8500/9000 rpm on 99 octane.

I chose a Clewett twin plug ignition kit, in part very good, but with a poor heart/ECU.
After a lot of grief and a lot of money got it all to work with help from 3 x DDK helpers.

The negative was all about the Clewett system and their designer/manufacturer.

You will find it very hard to find an ECU system in the UK to fire twin plugs, and i was not ready to fight electronics but Tim's solution works (on twin plugs?)

My experiences are:
Do not buy from the USA
Buy from UK sources
A lot of specialists of components here know little about flat 6 Porsches and twin plugging them esp on a budget. Tim's approach could be just the ticket for you.

Anyway, it all worked out well, 100 bhp / litre which was the aim and £10,000 in parts, 6K spent in the USA.

The engine was DIY build.

Read you thread on the twin spark conversion Graham and wholeheartedly agree on the buying from the states etc. Clewett have stopped using the supplied ignition control unit they supplied to you.
Clewett have some very nice trigger wheels and sensor holders that I am looking at on their website. It would be good to get your views of dealing with them.

It’s partly down to reading your thread is why I am erring on the side of a Speeduino or Megasquirt ECU (open source programming and lots of support via the forums etc), and the Triumph throttle bodies, (cheap).

Twin plugging and controlling the firing is relatively easy f you know what you are doing with the software using today’s modern electronics coils have a 12V supply and are triggered from the ECU. Running a wasted spark system I would be firing cylinders 1 and 5 on one coil pack and the same on the other with one output from the ECU

[SeanP]

If you are on the DDK get together feel free to quiz me about my Targa. 2.2T Triumph ITBs crank fire ignition.

Trying to get to one of the days. Work commitments and life getting in the way.

Are you doing the Sunday?

Regards

Sean

[Northy]

There is an excellent write up on fitting Triumph ITBs to an SC on impact bumpers : https://www.impactbumpers.com/forum/ind ... is-to-efi/

[Bruce M]

I run speeduino with Honda CBR throttle bodies on a flat4. Not the same but plenty of parallels. The most tricky bit was the linkage & it needs to be right or it’s a pig.

Cost around £500 all in, for the fuel & spark build.

Will be starting a type4 build after summer, with speeduino, plenum intake & maybe a turbo. Could do the CBR TBs again but leaning towards a single TB this time.

[hot66]

I’ve been running high comp 2.4s motor on clewitt twin plug system since around 2010. I can’t remember but I think I’m 10.3 cr

For me, we set it up on Neil Bainbridges on engine dyno and since then I’ve never touched it. It’s a fairly basic system as have 3 knobs to adjust the advance at specifc rev ranges.

Can’t fault it really . Any tuning I’ve needed to do is mfi based

[PeterK]

I’ve just started buying buts to do the same to my SC - I’ve now got a pair of Triumph TBs

As I didn’t mod the camshaft rear cover during my resto, and am too lazy to drop the motor, so I’m (initially at least) going wasted spark

Phill (see his Triumph TB thread on IB) used MS but now is a fan of MaxxECU (going in his BMW). My local tuner (Ray West - tuner of race cars at Thruxton) recommends SCS Delta 900. Probably about £500 more than MaxxECU Street but can run twin lambda & (why but if you really want to tinker) different maps for each bank.
Ray also recommends Kawasaki bike CoP

Was trying to buy a GoingSuperFast trigger pulley but no response, so may end up using a TriggerWheels bolted to my crank pulley - anyone know any others less than USD450 plus tax & shipment ?

[911hillclimber]

The trigger wheel etc from Clewetts were excellent and the major draw to the company at the time. Those 'mechanical' parts were nice and installed well.

The ECU has 3 screwdriver adjustable pots to tune the engine, but do not confuse this with mapping in the modern sense.

Years ago i amassed all the parts bar the ecu for a triumph bodies conversion to this engine, but costs come in to arrange things and mapping let alone all the messing abut.
Reliability is key.

In hindsight i would have bought a DTA ECU as it can deliver twin plug and a very good mapping (assuming it is done by someone who knows what they are doing.
If you have a favorite mapper in mind, fit what he says as you will need his expertise.

As a DIY project this caper is good and interesting but my need was for an affordable effective system that would be reliable as I was racing to win.