Can someone tell me at what point a throttle body is to big for an 1835 non-turbo engine ? I have two throttle bodies to choose from a stash of parts I have one is a 40mm Saturn 1.9L the other a 60mm Mustang 3.8L. Both have a TPS but the Mustang has a better linkage set up so I would prefer to use the Mustang unit.
I'm going to make a simple T manifold or use a progressive intake manifold with an adapter plate to connect everything. Do you think the 60mm will be to big, if so what about if I use a reducing hose off the TB to the air filter to make things a bit smaller.
Maybe a reducer like this connected to an air filter box?
With the 60mm, the first half of throttle will be overly sensitive and the second half won't have any effect because the engine will already be effectively at "wide open throttle" well before the actual throttle is fully open. Adding a reducer in front of the throttle isn't going to change that. The throttle acts just like a variable diameter pipe, and flow through a pipe into the engine is essentially limited by the smallest diameter. If the airbox opening was 40mm, the throttle will work normally until it opens to around an effective 40mm in diameter. If it opens farther, the airflow is effectively capped by the airbox opening instead of the throttle so opening the throttle more has little effect on the engine. Same effect happens when the engine has less airflow capacity than the throttle body.
Last edited by jhoefer on Thu Apr 23, 2015 9:27 am, edited 1 time in total.
