Header/Up Pipe Questions

[NyCowboy87]

Going to be running a t6 flanged charger on a full built pulling truck and while just fooling around with some flanges and some piping, I noticed a large difference from the size of the factory 2" up pipe to the entry of the t6 housing. The housing is divided and a 2" up pipe will almost fit inside the entry to the housing. Not only will it make it a pita to fit up and make look nice but I'm kind of worried about creating a "dead" spot at the entry with such a size difference where exhaust gasses can cool and lose velocity. I fit a 2.25" piece of pipe up to it and it fits nicely. However I don't really want to run a reducer down to 2" for the same reason I mentioned above so I was thinking about building my own headers and up pipes with larger tube. Factory ports are 1.5" so maybe 1.625 or 1.75 primary's with a 2.25" collector and up pipe, which brings me to my question, will I be shooting myself in the foot by going larger? I know it could potentially have a negative effect but has anyone ever toyed with a larger up pipe size?


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[ja_cain]

It may significantly lower exhaust velocity on the low end which might hurt spool up time. I could be way off on my reasoning though.

 

[old man dave]

Seems to me, I read the same thing somewhere about the gas velocity affecting spoolup.

 

[ja_cain]

Seems to me, I read the same thing somewhere about the gas velocity affecting spoolup.

That's essential what the different a/r setups do. The tighter the turbine housing (lower a/r number) the higher the gas velocity but drive pressures can become an issue at higher boost numbers. It really just shifts the power band around.

 

[NyCowboy87]

I'm not really concerned about "spool up" I've got as much time as I want to spool this thing up. What I don't want is to have it be a lazy pig and fall off the charger when it starts to load it hard at the big end of the track.


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[psduser1]

If your not looking for bottom end response, I'd probably open the exhaust ports as far as possible, and run the 2.25 pipe.
No expert here, *disclaimer*, lol, but from everything the seasoned guys say, these blocks will tolerate a lot of airflow, if you have the fuel to keep the heat up.