3" to 4" charge pipe.. Bad, good?
 

I just got through fabbing up a 4" charge pipe from intercooler to throttle body. The SPIKE turbo kit came with all 3", but I'm gonna run more boost in the near future after this tranny swap, so I fatten up the charge pipe some so my MAF wouldn't max out. My concern, are there any downfalls to running larger charge piping? Seems like everyone runs 3" or 3.5" max?

When i had my turbo. My charge pipe transistionex to 4in. Only reason i did it was to mate up to the TB better. I did it when i swapped to the holley high rise. I had to replace/redo that section anyways. I did it for looks and nust because.

follow any build ive done and youll see i go right off the intercooler into 4", i typically mod the outlet of the intercooler and weld a 3-4 transition onto them. this way 4" runs all the way to the TB

also on a maf based setup youll want the range of the 4" tube

I was thinking about doing the same thing off the intercooler with a 3" to 4" piece from cx racing! Maybe on both sides... Just to make it match!

That's exactly why I needed the 4" piping, for the range! With the 3" my ls3/7 MAF was maxing out around 9ish pounds.

keep 3" off the turbo into intercooler, then step to 4" right off intercooler

I would really like to see some testing on this. I run 3.5" from my turbo in and out of my intercooler to my throttle body. My father in law has a 600+ cubic inch pulling tractor and he runs a 3" pipe off of the intercooler and 3" throttle body at over 100 PSI of boost and he thinks it isn't hurting him. I would like to test it with a pressure sensor in the intake to see if there is a pressure drop from the restrictive pipe.

you want to keep the size of turbo to the intercooler

example my old pt91.5 was 4" outlet, that would be 4 to intercooler and 4 to tb

my twin 7675 are 3" outlet so 3 to the intercooler inlets then 4" out

other setups ive done...2.5 out of turbos...so 2.5 to intercooler then 4 to tb

since all tbs are 4" ive used

also one big block i worked on had 5" going to the Hat and and dual 3.5 feeding the 5"


no sense in running larger then the opening of tb

Cool thanks! I'm gonna keep the 3" on turbo side and re-tune with the 4" on throttle body side.... Also I'm gonna dyno it next time with the air filter off! I was just reading up on that thread over in the dyno results section, good stuff!

i always dyno no filter, then run on street with filter...may richen up some but least safer then being tuned for fitler then removing filter.

saw enough filters that caused restrictions or issues in boost to run them when running hard