Hey world...i come to you with another question...

I recently got a A14...and...im thinking of going down the EFI route...and the road i want to take is the individual throttle bodies(ITB's) road...

By my calculations...a NA A14 engine should have ITB's with about 34mm diameter...more than this would be killing low end power...and that i do not want to do...and 34mm would meet the A14 intake port size also...

I have been looking at ITB's form bikes...and they look as the best alternative...the problem is that i am not really in to bikes so i dont know the specs...getting to the point...does anyone know a bike that uses 34mm throttle bodies?

thanks a lot...peace world...

Hi Ronny,
I just googled for you...

BMW K1100RS 34mm bodys
KAWA. GPZ1100 34mm
KAWA. Z750S 34mm

If you could get to a wreakers and check these out, one set might be easier to mount..

Hope this helps, Simon.

Hey...thanks a lot...i searched Google and didnt find any usefull info...hmmm...this is gonna make things easier...

If anyone knows more bikes or something that uses 34mm throttle bodies please write...

Once again thanks a lot sikyne...im gonna start chasing these...hehe...peace...

over 34mm would be over kill ever had a good look at twin sidey webbers or dellortos? they are people use 40's 45's and 48's without to much problem so i dont see why you cant go to 40mm?

toda quads are based on 4age 20 valve throts
rally1200 has made a set with good results
dazza

Quote:

But those 40/45/48's are choked down remember...

34mm will be large enough unless you are running a race motor.

I run 40mm dellortos choked to 33mm on my L16, 42mm's choked to 36mm on other L16 with headwork and racecam.

I would recommend going with 40 ITB's.
Almost all people on this site who run Sidedrafts or Dellortos use size 40. From the A12 to the A15 engines.
Also remember that carbs apparently are bit more tricky to drive and not as smooth in power delivery than ITB's.
Don't be fooled by the 40's. It's fuel injection.Will be fine.

If you go with a bore to big like 40mm or 42mm you will lose air flow properties...the smaller the bore the quickest the air rushes in when you fully open the throttle...

Look at this quote:

" A. What is the best throttle body diameter?

Factors influencing size are: Power output, rpm, cylinder head design, cylinder capacity, position of the throttle body in the inlet tract and position of the injector.

Choice of bore size is a balanced compromise resulting from the following:

1) A larger bore leads to lower flow resistance, but obeying the laws of diminishing returns.

2) A smaller bore leads to better throttle control and response (never underestimate) and improved fuel mixing.

3) The system should be considered in total - from (at least) trumpet flange to cylinder and proportioned accordingly.

Basic references for BHP per cylinder, assuming ca.(ca.= approximately) 120mm from butterfly to valve head and a max of 9,000 rpm are:

Up to 30 BHP/CYLINDER - 30mm
up to 33 BHP/CYLINDER - 32mm
up to 39 BHP/CYLINDER - 35mm
up to 46 BHP/CYLINDER - 38mm
up to 51 BHP/CYLINDER - 40mm
up to 56 BHP/CYLINDER - 42mm
Up to 65 BHP/CYLINDER - 45mm
up to 74 BHP/CYLINDER - 48mm
up to 80 BHP/CYLINDER - 50mm
up to 87 BHP/CYLINDER - 52mm
up to 93 BHP/CYLINDER - 54mm.

These power figures may be increased by up to 10% in a purpose - designed, well proportioned system.

As butterfly to valve distance increases, butterfly size will need to increase in proportion to system taper and vice versa.

Lower revving engines and those with injectors placed before the butterfly will generally accept a larger body. "

from the web page:

ITB's info Site


I also have a book that explain all the whole air flow stuff...so my question is...i know there are a lot of people runing 40mm and 42mm and 38mm...but is it runing at maximum eficiency? are you getting all that you can out the the ITB's?

Big isn't always better...thats why we drive Datsuns and not Mustangs! hehe

hmmmm, interesting.
I was under the impression that with fuel injection because you can tune it far better and in more detail that 40mm throttles will be OK.

isent that wat a O2 sencer is for? ad throttle position sencer's and sutch? so ther is optimum fule at all times? I would hav thought the bigger the betta with injection, and just let the the coputers work it out?