I've had a search about and can't find much info on what impact changing the turbo to core fmic pipework bore has (if any) .

I'm running a hdi fmic on my 94 sti and want to reroute this stretch of pipework up past the d/s cam cover, Rather than up through the inner wing as it is now

The existing pipework changes dia near the maf and if i shorten it I don't want to end up with more lag



but a increase in spool or torque would be a bonus ;-)
Has anyone else done this or looked into it and if so how much of the narrower dia pipe did you retain ?

 

If you shorten the pipe work I wouldn't have thought you would have more lag.If anything you would get less.I don't seem to have any lag on my Forester with the Td05 on and front mount Clive.In theory I think its surposed to work out the less pipe work you have with less restrictive bends the better off you would be.

 

Also, if i understand correctly you want the smallest diameter pipework that can flow the amount of air required by the engine (when it's making max power it can) this ensures the fastest airflow and therefore spool and efficiency.

 

Yeah I gather that shortening that stretch of pipe work will lessen lag a bit and that the most restrictive part will be the turbo "swan neck" exit .

I'd just like to make sure I use the right amount of each bore pipe as the bore increases at the joiner near the maf in the above pic .logically velocity of the air will increase in a bigger bore but pressure will drop in a bigger diameter pipe (more area to fill)

Think I might have to just measure the length of each different bore section and use the same ratio length of each bore with the new pipework.

Thanks for the input chaps any other comments/points welcome