[HayBurner408G]

Hi David,

Thats brill, thanks for the pointers.

Valid point Re period look , think i just need to get out my head that trigger wheels look funky - thats a good example of how to hide one as well.

Ive found some throttle bodies that appear suitable, but am going to continue swotting till i feel like i have enough of a close outline of everything that needs to go into this.

cheers

Toby

[HayBurner408G]

Right. A couple days swotting later and I think i am starting to get an idea of what I am planning

rather than split an inline 4 FI bike i am thinking of a pair of parallel twin throttle bodies.

MT07s make similar power to approximately half the output of what I aim and think is achievable with the bottom end I have built. The TPS is a 3 wire type, and the injectors sit just below the butterfly. There is also an Idle air control valve which is built into the body so less hacking other bits up.

So, from the top:

Crank trigger wheel either off dizzy drive or crank pulley machined into face

"modern" ignition module (inbuilt coil driver) (I have a spare off a mk3 Polo) - same style as sold on DIY-EFI.co.uk - aiming to run a wasted spark setup.

A pair of mt07 throttle bodies (only foreseeable issue is duplicate sensors IE 2 TPS etc etc - can speeduino handle this?

Use a VDO CHT sender or whatever I can nab at scrappy, same for IAT (drill and tap for a bung to go into air box/breathers?)

Use recommended MAP sensor

Wide band lambda


Fuel system and from post-it calcs I am nowhere near 044 fuel pump flowrate, Instead looking comparable flowrates of big displacement motorbikes and high bhp/cc small cars - I think 60-70LPH should be enough (providing I havent cocked up numbers). As on a beetle the fuel tank pickup is right at bottom I am not sure if air being sucked in is as big an issue, but think I could squeeze a 1L surge tank underneath that is gravity fed by the tank and then to the pump (so all will sit below the fuel tank to keep a pressure head) I will run a return line the same route as the feed (can you have it exit in the bottom of the tank also (with some sort of 1 way valve?) or into the filler neck.. fuel pressure regulator just before engine bay then to a common fuel rail which will serve both cylinder banks by teeing to each pair of throttle bodies (equal distance between)

I cant find much info on the injectors online but believe them to be made by denso - part no:297500-2310 so flow rate etc are just very rough figures.

Ive mocked up some manifolds too - thinking of laser cutting the mating surface to cyl head then using stainless pipe. Throttle bodies mount with rubber/silicone boots and a clamp. however it may be easier brutalising some old cast manifolds and making adaptor plates.

Any input greatly appreciated - I am aware ive still got heaps to work out

cheers

Toby

[LAV1000]

Make a little more effort and make yourself a crank wheel and sensor, 36-1 should be fine.
This way you have solid base to start from and it will work for all the future options.

TPS, both throttle sets need to be linked in a mechanical way so just one of them will do, keep the other one as a spare.
IAC , I think you need both them for your idle operation, but I don't know if react the same.
Might be better to skip them and use a separate standalone IAc valve.

CHT, find a NTC type that whitstands 150 C.
The VDO CHT if it is thermo couple, you don't want that because you can't connect it directly to the speeduino.

Fuel pump try to find something like this, used on ATV'v
https://www.amazon.com/2007-2013-Honda- ... lp_pl_dp_1

Injectors, Motorcycle engines are making more revs than a beetle engine.
This way on a motorcycle they have less time to inject fuel so they are bigger then you need for your beetle engine.

Last remark, Boonstra Parts, your Dutch?

[HayBurner408G]

Crank trigger it is! from the books ive been reading seems like simplest and best method. In the space where dizzy/coil/fuelpump sit I can mount new coil and other gubbins...

That was a concern Re motorbike throttle bodies, I know flowrate is not the same as pressure, but was wondering if I could compromise by dropping pressure. (that reads stupid I know ). The throat size is comparable to perf weber/dellorto carbs but I know that Throttle bodies usually are a straight through with no venturi. Could I not also compensate by adjusting the pulse width/active cycle of the injector?

I was thinking I could blank one set of sensors, seems like I was on right track. Thanks for the pointer Re CHT sensor. wondering if I could use the CHT sensor also to meter fuel for cold start? no coolant means no coolant temps lol.

ATV fuel pump is a good idea - will look into that, thanks!


Ive read a bit around fuelling methods - batch, semi sequential and full sequential - correct me if I am wrong:

Batch seems simplest but could wet the manifold quite a bit and means more unburnt fuel. Easiest to map and reasonable performance

Semi sequential sits inbetween - alternative cyls fire at same time

full sequential you only fire on said cylinder - more fine tuning, timing and sodding about but most potential for fuel economy gains.

sounds stupid, but im leaning more towards batch (to start) for simplicity and that the curvy manifold design means the injector may spray onto manifold anyway. If full sequential mixture wont have much of a chance if its not in manifold for long (again more ramblings, but do you get the gist? ) whereas with batch fire their will be more of a chance for a homogeneous mixture and could help cool the valves a little (every bit of cooling helps being air cooled)

Another pretty incoherent post I know, but I feel like I am getting somewhere. As always, any input is greatly appreciated.

Thanks chaps,

Toby

[LPG2CV]

Hi Toby

I'm also working on an air cooled engine (Citroen 2CV). I've been on the forum for probably 2 years, and for one reason or another, have not gotten running on Speedy yet!

If there is one piece of advice that I could give, it would be do what you need to do to get running, and then improve from there.

Having said that, I've just fitted my trigger fly wheel. The most critical component in my estimation.

Watching this topic, and good luck with the build.

[PSIG]

Note — you likely already know a lot of this, but I describe stuff so other new users reading the thread can follow as well.

MT07s make similar power to approximately half the output of what I aim and think is achievable with the bottom end I have built.

Fortunately, oversized airflow is not a functional issue but a response (driver sensitivity) issue, so you may find progressive throttle linkage is desired. Also, just as with the other components the required airflow will be met at a partial throttle opening, so your VE Table resolution will be smaller, non-common plenum will tend to have less MAP resolution, TPS will have limited effective range, and other side effects. The injectors as @LAV100 stated will be very oversized, with again less resolution. I have no quarrel with any of it — it's your project. Just outlining side-effects that you may not have considered that you are choosing that can be obstacles to performance, tuning and operation. Compromise where you like and to the extent you are comfortable, but you only get so many sloppy choices in a setup, from injector sizing to timing resolution to fuel grade, before it bites you and goes from great to so-so.

Use a VDO CHT sender or whatever I can nab at scrappy, same for IAT (drill and tap for a bung to go into air box/breathers?)

Another option is any K-type thermocouple + AD8495 = There are other sources for the AD8495 board, but the info there is good. Install the AD8495 with power from your proto area, output to the CLT input, and calibrate in TS. Range is well over the VDO sensors and what you may need for CHT. Generally, a common CHT ring (under spark plug) sensor is used for best response and relative numbers, though other types can be used with consideration.

Ring_CHT_T-couple.png (43.38 KiB) Viewed 7389 times

think I could squeeze a 1L surge tank underneath that is gravity fed by the tank and then to the pump (so all will sit below the fuel tank to keep a pressure head) I will run a return line the same route as the feed (can you have it exit in the bottom of the tank also (with some sort of 1 way valve?) or into the filler neck.. fuel pressure regulator just before engine bay then to a common fuel rail which will serve both cylinder banks by teeing to each pair of throttle bodies (equal distance between)

If i understand your description correctly; the regulator would typically go after the fuel rails, returning any fuel not used to the surge tank. Feed can be to one rail and then the other (then the regulator), or tee both before and after to split the feed to and from the two rails.

The small fuel modules such as @LAV1000 mentioned for TRX680, VT750, VT1300, etc, are very handy, but be sure to get the connector for it and the quick-disconnect fuel fitting. A small accumulator/surge tank fed by the stock fuel pump might be an option to keep-up with the HP pump flow. 120hp needs a 50lph pump (fuel pump calc's here), and 50/60/4=.2L (7 fluid ounces) is the fuel you need in your surge tank to feed that full power for 15 seconds without any fuel from the tank. I know, rare, but it may as well be bulletproof.

A soda can-sized tank will take you for almost half a minute at WOT if your main tank is near empty, sloshes away from the outlet, and you go for a blast. Looking at those numbers, one of the billet oil catch cans could be a plug 'n play surge tank. If gravity feed with an up-sized tank outlet, consider the return to a high point in order to prevent the gravity head pressure from inhibiting return bubbles. Hope that helps.

David

An accumulator/surge tank I made from a truck fuel filter assembly, modified with a bottom pickup tube and 3rd port opened. It happily fed a turbo V8:

[HayBurner408G]

Hi David

Thanks for your reply - really appreciate you taking the time to give constructive feedback, its helped no end so far

From my understanding, the throttle bodies could work but I would have poor resolution to map them (as they are too large for purpose) making them a bit of a pig. I was considering popping different injectors in there - I like the idea of re using something that was designed for that specific purpose as I am still new to the world of EFI. Were my suggestions of changing pressure and/or active duty cycle pretty much irrelevant?

I am interested however in how other people have used ITBS and carbs of a similar size and got reliability and even power from them. Youtube yields that people have good results with cbr600 carbs and throttle bodies, both on smaller displacement t1 engines than what I have sat on a pallet in my living room - I wonder what their compromise was, or how they got around the issue?


Ive got a couple more books in the post coming today on the ins and outs of fuel injection so hopefully thatll clear up some of my misunderstandings/spots in my knowledge

I like the look of the cyl head temp spark plug unit but have always worried how the copper washer holds up with the plug being removed/refitted - have you ever had an issue with something of the sort?

Sounds like the swirl pot I am roughly on the right track but could get away with something even smaller - I like your use of the oil filter setup, looks very neat too!

Thanks again

Toby

[PSIG]

Were my suggestions of changing pressure and/or active duty cycle pretty much irrelevant?

Totally relevant, but there are limits and declining results. Any compromise is a compromise (and you can't avoid them), each being relatively ignorable, but each always moving away from optimal. Performance always engineers towards optimal. If you have enough sloppy compromises the project fails to fully meet goals or you find frustration in getting there.

This is why I don't say things like you're silly to do something or other. You can make almost anything "run", but will it meet your goals? Going into a project already knowing you will have to apply large skills or band-aids sucks. @LPG2CV put it well, to just get it running and make improvements from there. The big benefit is that (at this driveway-engineering level) you can't accurately predict what's great or sucks in a setup (or read enough posts) until you actually run it, so run it.

people have good results with …

Here's an example of an earlier statement, and my response is "Good compared to what?". If some science is applied along with good compromises, it could really perform great. ITBs can make some really great power … or not. Where is the difference?

Again, we can make virtually anything "run" and seemingly run "well", but at some point compromise sucks all the fun or misses the target. That point is entirely up to you and your goals. This is a matter of context. If you choose shoes 3 sizes too large, can you use them? Sure. Can you "run"? Sure. So, what's the problem? Perhaps nothing, but will you run as well or win at track or basketball? Probably not. So your goals are important.

Custom ITBs are relatively unusual on the street because the typical driveway engineering sucks and often the tuning, and therefore actual or perceived performance. That makes them impressive because you're willing to learn more skills and do the extra work to make them run "well". Bluntly, in hobby-level street ITBs, it's more impressive that your Mom can drive it than if they make better power. If yours is only a show car, then it only has to run well enough to get to the show. If that's all you need, then running relatively** crappy is running "well" for that. Set your goals and choose your compromises. Enough of that.

I like the look of the cyl head temp spark plug unit but have always worried how the copper washer holds up with the plug being removed/refitted - have you ever had an issue with something of the sort?

What CHT temperatures do you expect? I've had no issues with spark plug sensors. They are robust with reasonable care, such as supporting the sensor wires. Yes, after dozens of plug changes they can stretch (especially taper-seat types); but at that point it becomes a performance consumable like the plugs or O2 sensor. There are lots of options, as no single solution is universally the best option. Choose what will work well for your application, or what you like. Hopefully both.

David

**"Relatively" could be 87 instead of 97hp, or poor low-end torque, or reduced responsiveness, etc. Or none or all of it.

[LAV1000]

Want to say something about ITB's.
Try to find some ITB's which matches your inlet valve and or inlet manifold tubes.
If you search ITB's try to find something of a touring bike, might be cheaper then from a sports bike and also smaller in diameter.
This mine opinion and you don't have to agree whit it
Info on ITB's and alot more info on EFI;
http://www.msextra.com/forums/viewtopic.php?f=94&t=6627

Injectors don't have a thread size they use O- rings to fit and something to hold them down
Info on injectors:
http://users.erols.com/srweiss/tableifc.htm

[HayBurner408G]

David + LAV1000,

Great stuff, more food for thought. That webpage listing throttle bodies is incredibly helpful, thanks.

I appreciate that I have fired many seemingly daft (or frustrating! ) questions but its really helped build up a picture of what is feasible in my head. A work colleague has an MT07, which means I can actually have a proper look at how they work and are made up before I make my decision regarding using them.

Ultimately I want to plan a few different style setups and then do a table listing whats good/bad (and cheap vs expensive!) and use that as my decision maker.

Unfortunately my studies start again soon so this may end up on the backburner, but will try to post my ramblings on ideas on here as often as I can. (can you emulate speeduino if you want to tinker with it at a desk?)

I also got hold of a somewhat ancient mapping software (emerald M3DK) which came with a couple of fuel injection manuals that I have been swotting up on. Is it worth trying it out or is it a dinosaur in comparison to tunerstudio?

cheers

Toby

PS weather was nice today so went for a spin - shes starting to scrub up ok!