I'm fitting a set of GSXR 600 throttle bodies to a 1.8 Zetec, I was going to make a manifold myself. I don't want to re space the throttle bodies so I was going to use the existing rubber mountings on the throttle bodies, make a plate to suit them and angle the tubes between the holes in the two sets of holes. Does any one see a problem with this?
no but work out the distance to the throttle flaps . I'm sure there are threads on here and info on jenveys site about working this out and the effects it has!
Distance between throttle flaps?
quote:
no but work out the distance to the throttle flaps
It is easy to space the early Gsxr TBs you just need some 6mm studing and some spacers, the linkages can be bent to compensate although i extended
mine to fit.Hardest bit is the fuel rail but there are ways of doing that also.
Paul.
I would say attaching direct to the engine would give a short total inlet length........
Don't be too woried about spacing them - It's not a difficult job....You could then attach to your existing manifold - Like I've done -
I used the bend the throttle linkage method -
Click
This shows them offered up to the engine (not yet bolted on though):
Click
[Edited on 22/2/08 by Jenko]
The Throttle bodies that I have are not separate, you would have to cut between no. 1&2 and 3&4.
Will it make much of a difference if the two outer pipes are slightly longer?
Having sharp angles (rather than smooth bends) in a manifold is not ideal in terms of airflow, and IMO rather defeats the purpose of fitting something designed to increase performance.
I did mean inlet length! ~
(from Jenvey site)
What is the correct overall system length?
Induction length is one of the most important aspects of fuelling performance engines.
In our experience an under-length system is the greatest cause of disapointment, with loss of up to 1/3 of power potential. There are a number of good
books on the subject and the serious developer is referred to these and, in particular, dyno trials. A guide figure, from the face of the trumpet to
the centre of the valve head is 350mm for a 9,000 RPM engine. Other RPM are proportional, i.e. for 18,000 RPM the figure is ca 175mm.
Any air feed system to an airbox or filter can have a large effect on the power curve and must be considered carefully - particularly if the airbox is
small.
The induction system is part of a resonant whole - from air inlet or trumpet to exhaust outlet - and the ideal length is heavily influenced by the
other components.
What is the best position for the butterfly?
The butterfly is an important aid to fuel mixing. When positioned too close to the valve this advantage will be lost whilst positioning far away may
lead to a loss of response.
As with the injector position (see below), higher RPM demands a larger butterfly to valve distance. A practical minimum figure for a 7 - 9,000 RPM
engine is 200mm, whilst the maximum is dictated by the need to fit an air horn of reasonable length to achieve a good overall tract shape. One
solution to this apparent compromise is the use of bodies with fully-tapered bores which, in effect, extend the trumpet distance beyond the butterfly
and into the manifold. For very high speeds above approximately 15,000 RPM, the ideal butterfly position is only just inside, or even outside the
trumpet and a point is reached where a taper is no longer sufficient for good tract shape. For these circumstances we can supply bodies with the
exponential trumpet shape machined into them as a special service, or barrel bodies which, by their nature, must be purpose-designed in conjunction
with the cylinder head.
Where is the best place for the injectors?
Where one injector is to be used per cylinder the best compromise position is immediately downstream of the butterfly. This gains maximum advantage
from local turbulence and gives results surprisingly close to the optimum at both ends of the rev-range. This is the recommended position for most
applications
For performance at low RPM, economy and low emissions the injector needs to be close to the valve and firing at the back of the valve head. This is
the favoured position for production vehicles.
For higher RPM (very approximately 8,000+) the injector needs to be near the intake end of the induction tract to give adequate mixing time and
opportunity. The higher the RPM, the further upstream the injector needs to be. As a result, use of speeds above approximately 11,000 RPM may give
best results with the injector mounted outside the inlet tract altogether (see our remote injector mounting). It is common to fit both lower and upper
injectors in such a system to cover starting and low RPM as well as high speeds.
The induction system length is important in theory but in most sevens it would be impossible to have the ideal length and keep it under the bonnet, or
even with a cut out in the bonnet it would need to stick out so far as to be impractical.
Just make it as long as possible with a suitable air filter protrusion from the bonnet.
Paul.