For all you turbo gurus out there, whay dont i see many/any manifolds with 4-2-1 collectors, why does everyone use 4-1, info and explinations on this would be great

 

I think its mainly due to space concerns.

 

I think its because most topmount makers start making ramhorns/shorties, which supposedly takes forever & ever to develope due to the collector jig being harder to make than anyone could possibly ever fathom. Then since they have that jig, they just keep using it to make collectors, rather than making a very simple jig to make a 2-1 collector. Either that, or they're just supplying the bandwagon with the supplies it requiests to keep steaming ahead.

Eventually I'll make a nice 4-2-turbo mani when I actually get a GT30 with a divided T3 flange.

 

so seems to be just because its the way its been done in the past, and cant be bothered changing..

is there any performance variations between the two.. ie pros and cons, will one spool up better, or give better torque figures etc?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by gt3076r &raquo;</TD></TR><TR><TD CLASS="quote">For all you turbo gurus out there, whay dont i see many/any manifolds with 4-2-1 collectors, why does everyone use 4-1, info and explinations on this would be great </TD></TR></TABLE>

Mainly because it's easier to fab this way with the space we're given, and secondly because unless this is for a divided turbine housing, the two collector styles will operate just the same.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Boostwerks.com &raquo;</TD></TR><TR><TD CLASS="quote">
the two collector styles will operate just the same. </TD></TR></TABLE>

You're saying the 4-1, and the 4-2-1 would perform the same right ?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RCautoworks &raquo;</TD></TR><TR><TD CLASS="quote">

You're saying the 4-1, and the 4-2-1 would perform the same right ?</TD></TR></TABLE>

pretty much. I mean if it was paired 4-1 and 2-3 i could see it reducing reversion somewhat in a 4-2-1 design, but unless it's divided to the point of the turbine wheel I don't see it making much of a difference. I could be wrong though, but I'd be willing to put money on it.

 

There are performance differences....Short runners aren't always better in a turbo application.

 

just my persoanl opinion...when you start gettin into bigger power aspects id think the stepup bewteen the 4-2 and 2-1 would have to be so large to compensate for the increased exh volumne that you would lose some of the exh velocity

also key to keepin turbo's spooled is the exh pulses...when you start mergin the pulses together earlier in the stream id thnk youd see some pulse interference

but it has been done...cody aka lovefab built one awhile back that was a 4-2-1 for a sidewinder mani....looked decent...but the 4-1 merge is just pure sex

 

There is a lot more to manifold design than exhaust velocity.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by k24em2 &raquo;</TD></TR><TR><TD CLASS="quote">There is a lot more to manifold design than exhaust velocity.</TD></TR></TABLE>
yea i understand that...but i think to get a manifold to be equal on all aspects the 4&gt;2&gt;1 would be harder to generate esp w/ mixing the pulses...even on most divided housing mani's many keep the cylinders separate until almost at the turbine...and i think it would really effect the pressure differential across the whole system even more so than the standard 4-1 setup