weber twin 45s on a g-limited

[telavich]

picked up a g-limited very cheap (£70.00) got it through the mot only needing minor work and am impressed with it but do like a set of carbs i have fitted carbs to a couple of previous cars i've had and got good power from them i just wondered if anyone has fitted twin 45s to an mr2 and what the result was apart from the obvious fuel consumption?

[phipck]

im not a hugely knowlegable person with regard to engines, but wouldnt you need to completely alter the induction side of the engine, ie replace the manifold ect

you would loose out on the power increase at 4500rpm due to the acis system, but may create a stable powerful engine?

[LimeyMk1]

I'm sure it's been done before but have you considered using throttle bodies and retaining the fuel injection system? It'd give you better fueling control.

I'd be suprised if Jenvey didn't make a setup for the 3SGE.

I appreciate ITB setups are probably more expensive than carbs as you'd need a standalone ECU etc.

From a quick Google search it seems like a few people in New Zealand are running a Weber setup on their 3SGEs.

http://www.garagedori.com/tech/conversi ... /index.php

http://www.fraser.co.nz/Manifolds

Manifolds from the States:
http://www.paeco.com/Weber%20Conversion%20Kits.htm

One thing to consider is the clearance between the head and the rear firewall, it may be pretty close.

Video of it running when it's finished will be required of course.

[.jambo.]

i thought about this ages ago but with bike carbs.seems no one has tried it would think it would be a good set up though.

[bill]

i had twin carbs on my 205 mi16, what a giant slayer it was lol

[Ryan S]

picked up a g-limited very cheap (£70.00) got it through the mot only needing minor work and am impressed with it but do like a set of carbs i have fitted carbs to a couple of previous cars i've had and got good power from them i just wondered if anyone has fitted twin 45s to an mr2 and what the result was apart from the obvious fuel consumption?

i fitted twin 40mm webbers to a 1.8 mazda engine, you NEED to get the injector ports bunged up, you'll need a fuel pressure regulator of some sort(adjustable), and i think you'll need a solid state fuel pump, this thing went like stink with the carbs on, i'd deffo do it again if i didn't have the tubby

[Bender Unit]

Unlikely you will find a inlet manifold to allow you to install the Webbers – you could make one though which wouldn’t be too difficult. Obviously you need to think about what you are going to do with the ignition and you may also find that they don’t run too great unless you have a longer duration cam in there.

I would personally suggest retaining the factory EFI injection and install some bike carbs. Simply seal the bike carbs so they just act as throttle bodies – the fuel is still injected through the head as stock. Then all you need to do is get some sort of piggy back (dastek - £100 second hand) to tweak the map to account for the increased air flow, and weak map signal. Only other thing to think about is finding some way of still running the TPS.

Do a Google on DIY ITB’s and you will see there is a lot of information out there on what you need to do and how you can construct the inlet manifold to hold the ITB’s etc.

fitted twin 40mm webbers to a 1.8 mazda engine, you NEED to get the injector ports bunged up, you'll need a fuel pressure regulator of some sort(adjustable), and i think you'll need a solid state fuel pump, this thing went like stink with the carbs on, i'd deffo do it again if i didn't have the tubby

You can get away with using the stock EFI fuel pump – I simply installed the tank return line before the FPR – the FPR would drop the fuel pressure down to 4psi for the carbs and the fuel that didn’t get through went straight back into the fuel tank. Saves messing with ticker pumps etc.

[Dundee]

I looked into doing this quite a while ago, (not to my tubby) If it could be done I think it would be fantastic.

The problem is I dont think there is room for the trumpets between the engine and the bulkhead. Webber 45's or 50's are rather long and even if they would fit on, I think it would be hard to get a good flow of cool air to them.

Maybe bike carbs as they are smaller

I think this may be part of the reason people dont offen tune the GE.
I'm sure some really good outputs could be had by running ITB's

[Ryan S]

I
The problem is I dont think there is room for the trumpets between the engine and the bulkhead.

that's what i struggled with, after the custom inlet manifold was on i had about an inch of clearance!!!

[LimeyMk1]

T'is the nice thing about having a V engine, no serious clearance issues for the inlet.

Sheppy do you remember what kind of inlet length you ended up with?

[RST]

Personally I can't see the benefit of carbs on an engine originally with EFI -it's always going to be a down grade for me. I would go itb's if it were me...

I have an itb set-up waiting to go on my 3SGE -OK it's a BEAMS so the adapter manifold is custom suited and 4AGE quad throttle bodies seem to suit it well enough. It sticks in mind that TODA do a complete itb kit for the gen3+ 3SGE and Rogue did an itb set-up on a Celica earlier this year (there was a video somewhere on youtube).

Here's the rough parts I got if something like that takes your fancy so you know roughly what to look for...

• Inlet manifold -mine's a custom sand casting
  itb's -mine are 4AGE ones (48mm ID if I recall)
  Trumpets -I got these from Jenvey, the base flanges don't have bolt holes on the correct pcd so I'm planning on making adapter plates, or use the base plate for a single sausage filter as the adapter (trumpet length of 40mm should suit me)
  I converted from MAF to MAP -plumbed into my inlet plenum when I ditched my stock ECU and went for a standalone Link G3XLEM.

...I'm guessing an adjustable fuel pressure regulator would be a wise move before they get fitted and I also have an oil catch tank to go on the PCV line and vent it to amosphere via a small filter.

You'll only really get the benefits from itb's if you've done some other mods like maybe fettled the breathing in the head, decent free flowing exhaust and I fitted a C-One flywheel and Helix stage 1 clutch at the same time my ECU was fitted. If you haven't got upgraded cams then it would be better to fit those also.

There are a few itb'd 3SGE's but not much on the internet (except some BEAMS ones). There is a tendency for the rear firewall to get cut or removed, but I reckoned with 40mm trumpets I had just enough clearance with either a sausage filter or throttle socks.

...not sure if that helps you but if you're going to tune the engine and change to itb's then that might give you a bit more to go on.

[Bender Unit]

FYI if space is an issue and your looking to use the 20v ITB's in a tight space use the stokc 20v stacks - they are mounted facing down on the 20v, but can be flipped upwards and the filter poitioned across the top of the stacks rater than to the side with a conventional ITB set up.

I have made my own stacks out of FRP - will try again using carbon when I have the time!

[RST]

^^ -yea, they're kind of like a snail shaped curved trumpet. Must admit I ditched the ones that came with my 20v inlet set-up as I was trying to match the trumpet length for the kind of power curve which suited. Some horrible rough moulding / join marks on the inside of the ones I had -guess it never affected a stock manufactured engine though.

[Ryan S]

T'is the nice thing about having a V engine, no serious clearance issues for the inlet.

Sheppy do you remember what kind of inlet length you ended up with?

it was a bit of a brute, i'm sure it was about 3 maybe 4 inches, this was on an old mazda 323f GT( the pop up lamp ones), 45's flooded it but 40's were spot on, was a bit lumpy when it was cold( and there was no choke) but as soon as it warmed up it was great, the sound of the carbs sucking air in was stunning!!!!!

[Ryan S]

i also had an old mg midget that was tuned as well( my first car) the inlet manifold( and i'm not kidding) was about 6 or 7 inches long, it looked sooo f*cking stupid!!! was also bore out and had high lift cams, it was brilliant, until the oil filter pipe burst and it seized!!!!!

[LimeyMk1]

it was a bit of a brute, i'm sure it was about 3 maybe 4 inches, this was on an old mazda 323f GT( the pop up lamp ones), 45's flooded it but 40's were spot on, was a bit lumpy when it was cold( and there was no choke) but as soon as it warmed up it was great, the sound of the carbs sucking air in was stunning!!!!!

Cool, the V6 is on 38mm GSXR ITBs and the inlet length is nearly 12 inches (trumpet top-valve), should keep the low down torque nicely.

[Ryan S]

bet it sounds good too

[LimeyMk1]

bet it sounds good too

I'll get back to you on that one.

[madbasshunter]

I had a mk3 escort xr3i that I converted to twin 40 dcnf webers (which are down draught carbs) so I cut a hole in the bonnet which the itg filters poked threw with a suzuki jeep bonnet scoop over them. It went well and was a lot better than the injection system, it was bored, l&b, bvh, piper cam, janspeed manifold & system, adj fpr and quaife lsd .

[Bender Unit]

^^ -yea, they're kind of like a snail shaped curved trumpet. Must admit I ditched the ones that came with my 20v inlet set-up as I was trying to match the trumpet length for the kind of power curve which suited. Some horrible rough moulding / join marks on the inside of the ones I had -guess it never affected a stock manufactured engine though.

To be fair they do look like comeplete shat but the difference in performance between them and a nice smooth stack with a nice parabolic lip will be negligible on anything but a seriously tuned NA.

Look at all this love for noisy NA's! Surpised no one has chipped in with "just turbo it!" yet