Triple webbers vs ITB: educate me

[Sykohtic]

So I've been a lover of ITBs and fuel injection forever. And I've had plans since forever to install ITBs on my M20 as soon as I can afford it. However I've been reading into high horsepower NA m20s and with that comes reading a lot about what people have done with the flow in the top end of the motor. The thread I'm enjoying right now is this:
http://speedtalk.com/forum/viewtopic...31132&start=15

Obviously the insane 350whp NA M20 described is amazing and has an insane amount if custom work, but some of the principal's from it are inspiring. And it brings the question to mind that's probably been answered many times: Triple webbers vs. an itb kit.

Obviously tuning comes in to play here. The ITBs are fuel injection that megasquirt can control. It's a computer so it can be consistent and will need less attention. Carbs will need to be adjusted regularly, and that will require me learning carbs. MS can still run wasted spark timing with carbs installed. There's a poster in the linked post that mentions (check page 1 of the forum post) something about better fuel blending with carbs and something about itb setups liking different things in the intake. I'd always sided with the consistency and reliability of fuel injection, but I admit I'm curious about the carbs. Putting them on an M20 is really similar in cost to the RHD itb kit. Plus then MS can be used to run an individual port meth injection system for det control with higher compression. I plan to have the ports worked and expanded for larger valves so the intake can be optimized. Let's just assume this is my fairytale pipe-dream M20 and it has a roller cam conversion too and can rev to 8 grand. What are the benefits, negatives, compromises between side draft webbers and ITBs?

[digger]

Where you introduce fuel matters, for high hp you want fuel introduced further upstream like in a carburator to have more time to vaporise, atomise, helps with charge cooling etc. the normal fuel injection point at the valve is not the optimal. That's the only advantage of the webers. There isn't anything stopping you moving the injectors with fuel injection or using staged injection but it costs more. Also that race engine needs to run 42mm chokes to be able to tune it, on fuel injection setup no need to add what is just a restrictor

[TobyB]

I've messed with both. The Webers are fun- once you get to a certain point with them,
they make almost as much sense as fuel injection tables do.
Just a little less predictably. Or sometimes (but not always) reliably.

EFI IS a big step up for a commuter. It's closed loop, which is a BIG deal,
in that it'll fix minor misadjustments for you.

Honestly, for me it comes down to use and desire.
Is this your second car that you want to play with? Do you like rejetting? The smell of fuel?
Then DCOE is wonderful.
Is this your daily driver? Need to run in wet and snow? Costs you money
when it poops out? Are you comfortable with computers?
Then maybe EFI.

Just my take,
t

[Polygone]

I've been in the same boat. Dreaming about putting ITBs or Webers on my 87 325i convertible. I'm not interested in turboing my car. NA sound is just too inviting! Been looking at the 40mm RHD itb kit as I would want to tune for street use with a 272 cam. The 40mm would put the power band it a better place for spirited street driving.

I have a Lotus Super 7 replica with a 1600cc Toyota 4age motor that has been modified and runs Weber DCOE 40s and uses Megajolt for ignition timing.
Megajolt/Megasquirt software is pretty easy to tune and give you lots of feedback depending on what sensors you have hooked up so even if you don't have access to a dyno you can tune doing road test runs. Would recommend going with Megasquirt as your ECU upgrade either way you go.

Webers on the other hand are fiddly. I got the car 5 years ago and I 'm still trying to dial them in perfectly. I've read multiple Weber tuning books and got the jetting great for super high end hp but it's not fun to drive around my area so current tuning for a lower HP curve for street use.
Also with you go with Weber you would need a new fuel pump and regulator as Webers need low pressure(3psi)/high flow fuel pumps.
If you like to fiddle, love pure NA sound and throttle response Webers are awesome!

Have fun whatever way you go!