turbocharged inlet manifolds
turbocharged inlet manifolds
(OP)
Hello, was hoping for some advice on inlet manifold design regarding turbocharged engines.
I am considering two different configurations. The first is the conventional way of having a plenum contolled by one throttle body feeding all cylinders. The other was to use one throttle per cylinder with a presurised plenum hehind them.
Is one throttle body per cylinder still worthwhile on a turbocharged set up? It doesnt seem as popular as it does on NA engines but I dont know why.
Any help much appreciated. Thanks, Gareth.
I am considering two different configurations. The first is the conventional way of having a plenum contolled by one throttle body feeding all cylinders. The other was to use one throttle per cylinder with a presurised plenum hehind them.
Is one throttle body per cylinder still worthwhile on a turbocharged set up? It doesnt seem as popular as it does on NA engines but I dont know why.
Any help much appreciated. Thanks, Gareth.





RE: turbocharged inlet manifolds
However if the throttle is round and the head's intake port is oval you have the issue of rapid aspect ratio change in the runner which is not good.
So, has anyone done this?
RE: turbocharged inlet manifolds
Ive been considering this, Im in the process of turbocharging a 20v 4AGE toyota, which come stock with individual throttles as you describe. My thoughts are that individual throttles give better response, and the only reason i have abandoned them is because you can get a better MAP signal from having a single TB.
Nick
RE: turbocharged inlet manifolds
RE: turbocharged inlet manifolds
On most aspirated cars they can get away with it by tuning the engine off throttle position instead of MAP or Airflow meter.
This is exactly why you will see a lot of GTR skylines fitted with aftermarket Airflow meters or even twin airlfow meters when they have been seriously modified. GTR skyline engine have a one throttle per cylinder setup as factory fitment.
G-Reddy actually make a single throttle body replacement manifold for the GTR which allows the use of a MAP sensor.
RE: turbocharged inlet manifolds
you said you see a lot of skylines fitted with airflow meters, do you mean by this they are not fitted as standard. what do they use as std?
sounds like a plenum/MAP set up is the best method then when turboing.
RE: turbocharged inlet manifolds
A map sensed car is also going to be very sensitive to engine tune. It assumes a certain airflow at a certain inlet manifold pressure, but if there is any small change to valve timing or exhaust back pressure, you are going to have to go back and re map it. On the other hand going rapidly on, and off full throttle, a map sensor is going to respond faster than an airflow meter mounted a long way upstream of where the action is. This can be a problem with massive intercoolers and long induction pipework.
An airflow meter corrects for changes in engine tune to a certain extent, more/less airflow adds more/less fuel, so if you expect it to stay in tune over long periods, an airflow meter might be a better choice, if you do not have your own dyno.
RE: turbocharged inlet manifolds