Lotus Elan

Which EFI and why

PostPost by: rjaxe » Fri Apr 05, 2013 9:07 pm

Interesting thread, I am part way through designing a system based on Honda Fireblade 40mm throttle bodies and Denso Coil-on-Plug ignition. Wasted spark ignition seems to be popular but is there a preferred fuel injection concept - sequential I can appreciate but requires a cam position signal however I have also seen mentioned batch injection which I take to mean the equivalent of the wasted spark but in fuel terms. If this works then no cam postion signal would be needed.
Does anyone have any views/ experience/advise they care to share?
Richard
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PostPost by: elanman999 » Fri Apr 05, 2013 10:05 pm

Richard,
My only experience of coil on plug is with modern cars. Most of the major car manufacturers have had big problems with coil failures. The other thing with COP coils is that need to be secured to something so some kind of frame would have to be made.
From what I have read the major advantage with sequential injection is in emissions. There is very little or no power gain. So why bother. Obviously if you want to do it because of the challenge then fine.
Wasted spark ignition and batch or semi-sequential injection is simple and works fine all with no cam signal.
Just my 2p's worth.
Cheers
John
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PostPost by: Bud English » Fri Apr 05, 2013 10:50 pm

Richard- What John stated on wasted spark vs coil on plug and sequential vs batch injection mirrors everything I read when researching for my system. On a four banger, wasted spark really simplifies your ECU requirements. You only need 2 ignition channels (drivers) vs four for coil on plug.

Remember that 40mm bike throttle bodies will flow quite a bit more than 40mm carbs. It's a straight through shot with nothing in the way except the butterflys. Don't go overboard. Having said that, I'm planning on using CBR600RR throttle bodies on my 2.0l zetec motor and I think they are the same size or very close to the same as the 1000cc bike. Edit: Had to go look that up. It didn't sound right. My CBR600RR TB's are 40mm and the chart I looked at states 44mm or 46mm for the CBR1000RR depending in the year.

Are you going to use 8 injectors like the bike or 4? I'm toying with the idea to use the secondary injector bank above the butterflys and using smaller injectors below to improve idle and just off throttle tuning (as Honda designed them).

Russ- Lots of ways to go here for all budgets. Hope your recent job circumstances are short lived and don't force a move. Hard to beat where you live now. Been there with start up companies, including one of my own... :roll:
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PostPost by: rjaxe » Sat Apr 06, 2013 10:38 am

Thanks for the advise folks, I will go with wasted spark and batch injection and remove the distributor.
Bud, your comment on the Honda TB sizes and number of injectors is interesting. The TB's I have were listed as Honda CBR 900 RRY 929 Fireblade throttle bodies 00 01 and only have one set of injectors. The bore size immediately downstream of the butterfly is 40mm (I have just re-checked it to be sure). Now there is a possibility I have been sold something other than a Fireblade set-up and I am not familiar enough with bikes to challenge it. I had the bore size confirmed before I bought as I read somewhere that 40mm is the maximum sensible size to go for with a street set up, as you have pointed out from your assessment. The only ident. I can find is GQ60AANL15 marked on the underside of the TB's, the photo below shows my units as received.
Attachments
001(2).JPG and
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PostPost by: Bud English » Sat Apr 06, 2013 4:21 pm

Those look almost identical to mine, perhaps with slight differences due to year of manufacture. Mine are supposedly '06. The second set of injectors are installed in the air box above the TB's and spray straight down through the butterflies. Each injector has a 12 hole spray pattern. They're mounted in a cast bar that I can mount in a purpose built intake plenum.
Secondary a.jpg and
Secondary b.jpg and

I have the whole air box and injector setup from the bike so I can take the mounting position measurements from that. That's all assuming I have room in the +2 engine bay. It all looks promising.

Edit to add pictures.
Last edited by Bud English on Sat Apr 06, 2013 9:25 pm, edited 1 time in total.
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PostPost by: pauljones » Sat Apr 06, 2013 6:38 pm

Gents,

On Johns post i have attached part of my mapping, please feel free to use that as a base for your ignitition, its from a rolling road set up so will be very close to a spot on set up for using bike TB's. I carried out a lot of research before spending mega bucks on a full emerald system.webber Alpha was my preffered choice at first but i moved on from that, It depends what you want from your system really,i think most aftermarket ECUs have enougth injector drivers and ignition drivers to run full sequential management and make use of coil on plug for a 4 pot.only thing is you then need to run seperate exhaust sensors to make full use of it all as it can individualy tune each cylinder to its best setting.A single wide band O2 will do though.The best bit of advice i had was go for the ECU that your local tuner has most experience with,just so happened mine was emerald,and i liked the fact Dave Walker was a technical editor of CCC a while back.Had some credibility.
As far as the coolant pick up on the twink,yes it is on the wrong side of the thermostat,but your ECU will have a start up MAP,mine runs rich at the moment,but i will fit an O2 sensor and make use of further functions in the ECU to reduce that,and more control during normal use.Im currently getting 40mpg and before it was around 10 to 12 at best.so it will pay for itself eventualy.

Paul
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PostPost by: rjaxe » Thu Apr 18, 2013 6:12 pm

Folks, a few pictures of my Fireblade based throttle body assembly having virtually completed this part of the project. I am going to tackle the pump/filter etc next.
Bud, how is your project coming on?
Air Intake Plenum Assy 003.JPG and
Air Intake Plenum Assy 002.JPG and
Air Intake Plenum Assy 001.JPG and
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PostPost by: Bud English » Thu Apr 18, 2013 8:43 pm

Richard - That's looking good. I see you still have the wax unit (fast idle) in place. I'm going to try that as well. If it works, it's a lot simpler than some other approaches. Looking at both your plenum and John's it appears I'll have the advantage of quite a bit more room to work with (LHD). The only thing on the intake side is the wiper box.

I've set the EFI bits aside for the moment. I'm still body off and need a trial fit with the body on to see how much room I really have for the intake and exhaust side of things.

BTW, the number on my casting is GQ63BARD14. I'm a bit confused though. Your pictures are mirror images of my TB's. With the unit sitting as in your photo, plenum side away from me and the injectors facing up, the throttle position sensor and the fast idle unit are on opposite sides. The difference is present in all your photos.
CBR 600 RR Injectors cropped.jpg
CBR 600 RR Injectors cropped.jpg (28.03 KiB) Viewed 1346 times

On my setup the TP sensor is in the front. Maybe the CBR600RR and the Fireblade are set up different.

Right/Left hand drive motorcycles. I don't think so. :lol:

Brings up an interesting question though. Does anyone know of a problem with mounting these with the injectors on the bottom? The underside of the TB's are less cluttered and the throttle cable would be easier inverted. Maybe it wouldn't be good to have any fuel residue sitting on the injector nozzles.
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PostPost by: rjaxe » Fri Apr 19, 2013 6:22 pm

Bud, the major issue I had with the installation was under bonnet clearance, the lengthy fuel rail is very close at the front end. I contemplated moving the fuel regulating valve elsewhere thus enabling the fuel rail to be shortened but by removing some of the bonnet insulation locally and chamfering the top of the fuel rail the problem was solved.
I am going to see if connecting the wax element to the heater circuit will work satisfactorily, hoping to achieve a very simple arrangement.
It would appear that our TB's are quite different in detail, I cannot shed any light on why the TP and Fast Idle unit position should have changed, could have been an installation issue in the design evolution.
I see what you mean about inverting the TB's, the underside is a lot cleaner, however the manifold pressure sense lines would now be lowermost, generally not a good position for them.
Hope all goes well with your trial fit.
Richard
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