Can you fit 4 throttle bodies?

Anonymous · September 10, 2004, 17:03

Been looking into this through spyderchat and had little success. Has this been done or even discussed? if there is a reason why it cant be done, why is that? anyone with any info speak up thanks

aaronjb · September 10, 2004, 18:08

Yes it could be done - anything can, but it'll be a lot of work. Things to consider are:

The MR2 uses a MAF (hot wire type) sensor for airflow - if you switch to four throttle bodies, you'd have to switch to a MAP sensor (manifold pressure sensor) for fuelling. That would mean either a box of tricks to fool a MAF-ECU into thinking it was still looking at a MAF sensor, or a whole new ECU (Dastek, Motec etc) and custom loom etc.

The engine bay is (very) warm, and it's location at the back won't be as good for throttle bodies (which will be breathing off direct filters I imagine) as it is on a front-engined car (that's constantly getting fresh air in)

If you are talking about running four TB's and being turbo'd - very few cars do this (Nissan GTI-R is one that does). You no longer have the issues of MAF vs. MAP (as the turbo will draw through a single intake and then feed the four TB's), but you will have to use special (expensive) throttle bodies that are designed to take positive pressure.

AFAIK nobody has done this to an MR2. IMHO there are cheaper ways of getting power unless you really really want to stay N/A for some reason, and even then, TB's are right at the top of the curve of N/A tuning - i.e. when you want every last bhp.

IMHO,
Aaron

Tem · September 10, 2004, 18:08

Quote from: "mr-s newboy"Been looking into this through spyderchat and had little success. Has this been done or even discussed? if there is a reason why it cant be done, why is that? anyone with any info speak up thanks

You can.

But take a look in there...there really isn't too much room on the intake side. If you want anything decent in there, you'll have to chop the firewall and get rid of the softtop...

Anonymous · September 10, 2004, 18:31

i wont have to do that.

If i was to have four individual throttle bodies, and box them in through a custom carbon box, with two air outlets which would take air from both side vents, then theres cams? throttle bods need these.

I am talking 2zz here chaps

SteveJ · September 10, 2004, 21:13

As Tem says, there isnt room for 4 throttle boddies between the firewall and the intake ports. The only way (that I can see anyway) to achieve this would be to create an intake manifold that has 4 seperate pipes that allow the TB's to sit at the end of the engine.

Even then I can't see any benefit to increasing the air flow as there is no vacuum post throttle body on the stock setup when the throttle is wide open. This would indicate to me that the stock TB is just slightly larger than the engines capacity to breathe. The same will apply with the 2ZZ as it is still the same engine capacity - the only real difference is the additional cam profile change that occurs near the top-end (along with slightly larger injectors to cope with the additonal fuel required as the cam changes).

Now if we were talking about conventional carburettors (no fuel injection) then I could see the benefit.

SteveJ · September 10, 2004, 21:16

Quote from: "mr-s newboy"I am talking 2zz here chaps

You do realise that the 2zz is near enough identical to the 1zz dont you (except for the addition of another programmable cam change) s:?: :?: s:?:

SteveJ · September 10, 2004, 21:22

Quote from: "aaronjb"but you will have to use special (expensive) throttle bodies that are designed to take positive pressure.

Not so sure about that - the stock throttle body seems to be coping quite well in the turbo '2s at the moment.

What I think you mean is if you wanted to run 4 carburettors with forced intake then you would need units built to withstand positive pressure (and yes - they are dman expensive)

markiii · September 11, 2004, 01:05

2zz has a bigger throttle body than the 1zz, just for info.

and no they aren't interchangeable.

aaronjb · September 12, 2004, 11:12

Quote from: "SteveJ"What I think you mean is if you wanted to run 4 carburettors with forced intake then you would need units built to withstand positive pressure (and yes - they are dman expensive)

Sort of yes - we weren't talking about stock throttle bodies at all, so I was referring to the fact that you'd have to buy aftermarket throttle bodies that are either designed to take positive pressure, or buy aftermarket throttle bodies and modify them to take positive pressure.. We're talking about 'trumpet' style throttle bodies here, afterall..

Perhaps aftermarket throttle body setups are more like the 'stock' TB's on cars now - the ones I've seen have various vac/breather ports on the intake side that would need sealing etc if you went turbo on them.

Jap GT300 · September 12, 2004, 11:15

I had disscussed this breifly before. I have had both the 1ZZ (pre detonation) and 2ZZ priced up for a conversion at F1 in Brands Hatch.

The Kit was an individual 4x short trumpet carbon Fibre direct feed with full lengh IGT filter. Please note that this was measured up with use on a wide bodykit with a more beneficial air flow supply.

Considering the benefits I dont think it is worth shelling out £1200 (parts and labour)

Calculated 8hp overall increase from use in similar four pots that are actually front engine (Yes it was a nova). Will you really feel that?