What throttle body to use..........?

[Saascat1]

Hi Everyone

I am currently in the process of building a circuit/tarmac rally E30 2 door. I have put together a 3.1L stroker kit from IE and also replaced the entire valve train, upgrading to OS SS valves, Schrick Comp Springs and a 304 degree cam. I also have custom long tube headers and will fit a free flowing exhaust system.
The ECU/EMS I will be using deletes the AFM/MAF and uses a MAP sensor, also, delete distributor and utilise a magnetic pick up on cam gear. This means I can tune each cylinder for fuel and spark individually.

I have thought about using and E36 M3 throttle body, If I can find one, or an E34 M30 TB.

I dont have the money for ITB's even though I know this would be an ideal setup, I was hoping someone could point me in the right direction.

For the engine will remain NA as the custom pistons have been made for 10.5:1 compression, and I would have to lower that significantly if I wanted to use forced induction.

I welcome any feedback regarding this.

Eye Candy

[5Toes]

A larger throttle body isnt entirely necessary, many forced induction dudes get by fine with a stock m20b25 TB.

[AndrewBird]

FI guys don't need larger then stock throttle bodies because the air is being FORCED into the engine. An NA engine has to suck in air, so it is a much bigger deal.

OP, I can't help much for what you should use, but I can tell you that M/S50/2 engines have a different throttle position sensor then an M20, but I imagine that is irrelevant since you are running standalone engine management. There are a few companies selling big bore throttle bodies though for M20 fitment.

[Saascat1]

FI guys don't need larger then stock throttle bodies because the air is being FORCED into the engine. An NA engine has to suck in air, so it is a much bigger deal.

OP, I can't help much for what you should use, but I can tell you that M/S50/2 engines have a different throttle position sensor then an M20, but I imagine that is irrelevant since you are running standalone engine management. There are a few companies selling big bore throttle bodies though for M20 fitment.

THanks Nitro,

Can you point me in the right direction for any of those companies? Names or web addresses would be greatly appreciated.

[Saascat1]

Seriously, I could really use some help here.

Thanks in advance

[SGT4677]

What size (diameter) map are you planning on using?
It seems to me that you would want to match the TB size to the sensor but the intake inlet becomes the restriction at that point,or are you planning on modifying that as well?

What are you using for ems? Motec?

Nice looking build!

[Bimmer_man]

honestly dude id call VAC Motorsport they know a lot about racing M20 and they can tell you whats best for what your wanting to do i called them for a M42 build im wanting to do and they told me some things i didnt even think about.

[ak-]

http://www.westcoastriots.com/

[ak-]

And, http://www.r3vlimited.com/board/showthread.php?t=163627

Made an adapter plate to fit m30 throttle bodies to m20's.
4mm increase

[Bimmer_man]

http://www.westcoastriots.com/

well there you go touche:up:

[Tulok]

+1 on calliong VAC

[AlphaE]

I have no idea. But I APPROVE!!! That looks real nice. Nice build.

[Saascat1]

Thanks for all the input.

I'll call both VAC and Riot Racing and see what they can do for me.

As for EMS/ECU, I plan on running a MSPNP with MAP and IAT with a wideband O2 sensor and some MSD ignition goodies. I will be deleting the distributor and using a magnetic P/U on the cam gear + crank position sensor to enable individual spark and fuel tuning.
I'm thinking 44# injectors. But I'll defer to wiser heads on those before purchase.

Again, thanks for advice. I welcome further discussion and will post again once I have decided on a TB.



'85 E30 Coupe 331ir
'90 E34 Sedan 525i

[Saascat1]

Well, I called VAC and got a little advice but not much help. OK if I wanted to spend $4000 on ITB's. I was told that some people were using E36 M3 throttle bodies, which I already knew.
I also rang West Coast Riot Racing, several times, and got no answer. Having looked on their site I would probably have bought one had someone answered the phone. I guess it wasn't to be!

Ebay to the rescue. E36 M3 throttle body US$74.00 including freight to Australia. I still need to buy a TPS and a throttle cable to suit, but I would have had to anyway. The E36 TB is a gain of 4.5/5mm at the plenum side, a little more on the intake side as it is slightly funnel shaped.

If anyone hears of anything better/larger that might work post it here, I'll keep checking.

Thanks again to everyone for their input, it is greatly appreciated.