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MX-5 Throttle Bodies - Lowest cost options?
MilesBuilder - 2/6/15 at 10:04 PM

Hi, I have a general question about throttle bodies...

I'm getting back into my GBS Zero GT build. It has a Mazda 1.8 MK2 donor, and as the stock air plenum does not fit in the GBS frame, i think I need throttle bodies.

I received a quote from Jenvey, nice kit, but was a lot more than I paid for the whole donor car, at around £1400. GBS offer an ATR DCOE 45mm diameter throttle body kit for similar money I think but difficult to see what is required along with the basic kit.

What have others done for a mazda engine for throttle bodies? Maybe bike engine 45mm diameter ITB?

I have assembled a mega squirt ECU.
I will have a look in MX5nuts website now to see there for any suggestions.

any help welcome,

Thanks,
Miles.

PorkChop - 2/6/15 at 10:39 PM

You won't find many TB builds on Nutz; they're generally accepted as one of the final tuning steps as the OEM inlet isn't too bad at all, plus they lend themselves more to FI.

Blink Motorsport will supply a TB kit, but they usually follow the above, but they might be able to put something together for you. They're Jenveys IIRC. Skuzzle Motorsport also put together a high power 1600 with bike TBs but there was a lot of other stuff in that engine too.

SJ - 3/6/15 at 07:08 AM

A fabricated manifold and bike TBs will be your cheapest option.

Slimy38 - 3/6/15 at 07:27 AM

quote:
Originally posted by SJ
A fabricated manifold and bike TBs will be your cheapest option.


Pretty much what I was going to say, following a similar process to the various Zetec/Duratec TB builds. So 600cc TB's, custom manifold and MS (which you already have)?

I think it's a sensible route if you're considering a lack of space, and I have to admit I love the noise (I would be tempted just on that basis!). But it's not going to give too much of a boost, hence it not being an overly popular solution.

Here's a typical nutz thread;

http://www.mx5nutz.com/forum/index.php?showtopic=99345

big-vee-twin - 3/6/15 at 07:48 AM

GSXR 750 throttle bodies from a 2001 Suzuki have the same internal dim as Jenveys.

They easily split into individual TB's so ideal for respacing.

Mine are installed into a manifold custom made by Fastdan of this forum.

You will see some pics of my Duratec set up in my archive.

FASTdan - 3/6/15 at 07:53 AM

Hi,

We can do you the same kit as below, but to suit your engine for the same price:

Ford Duratec 1.8/2.0/2.3 Bike Throttle Bodies Kit GSXR1000 42mm *STARTER PACK* 2

Or, if you would prefer to do it in kit form we can supply any of the components individually. Drop me an email dan@danstengineering.co.uk.

SPYDER - 3/6/15 at 08:05 PM

quote:
Originally posted by big-vee-twin
GSXR 750 throttle bodies from a 2001 Suzuki have the same internal dim as Jenveys.

They easily split into individual TB's so ideal for respacing.


This is what I did. I respaced them to suit the 3SGE Toyota engine. This also allowed me to re-use my DCOE type K&Ns.
I cut the flange from a standard manifold and made the rest myself. I knocked up a sort of jig to hold the lot in position for welding.
The bodies cost £100. The silicon hose and jubilees £30. The rest cost buttons.

OP...These bodies may be oversized for your 1.8 engine. As already stated, 600cc type might be better suited. I would try to get re-spaceable ones. A perfectly straight inlet has to be better than a kinked one.



MilesBuilder - 4/6/15 at 12:07 AM

Many thanks to all for replies. Superb feedback.
The bike TB seems the lower cost way to go.
I would have to pull too many favours in our tool room for some self designed turned and welded ally work, and I'd be worried I would not know how to modify linkages and fuel delivery pipes; but looks the best low cost solution by far.
I will email FastDan soon, and go from there.
I can see this is going to be the complex part of this build, my deviation away from stock MX-5 air plenum and stock ecu, and going to throttle bodies and a megaSquirt (V2 I think) self soldered ecu (assembled not tested yet). I need a college course just to get all the variables in the mapping tune understood. It will be crying out for a DOE design of experiments to optimize it I think. but starting with a suggested map from a forum.
I knew I should have gone with GBS' suggestion of a 1.6 donor (where plenums fits), not the 1.8.

Many thanks,
Miles.