PTE SCM5031R Witch AR to choose?

[xxShaneOmac]

There are alot of options when buying this turbo from Extremepsi.co
I can fullfill all of the options besides AR.
Im going with wastegate off the o2
The choices are
.48
.63
I think.

Why one or the other?

Does one produce more lag and power while the other spolls quicker and less power?

I dont know much about AR sorry.

 

[daren_p]

Yes thats turbine housing A/R & your right on the money. The smaller A/R will provide quicker spool vs the larger A/R but it will also limit top end flow vs the larger A/R. Unless your trying your hardest to spool your 50 trim like say a 16g series, I'd opt for the .63 A/R to maximize the top end flow, where a 50 trim is designed to run. The .63 would be the "norm", or what most run on this turbo.

 

[xxShaneOmac]

Thank you very much sir.

There are no calculations for possible increase in top end / loss or spoll / losss of with differnt AR's are there?

I mean the .63 isnt going to spooll 300 rpms later is it?
or Is it like 50rpms?

Just kinda trying to get an idea.

 

[daren_p]

Personally I don't know of any calculations for this, but who knows there may be something out there. As for loss in spool, there are alot of variables but I would think that your going to see more then a 50rpm increase in lag. Probably will see a couple hundred rpms more lag with the larger AR, but don't let this worry you. The top end will more then make up for this small amount of additional lag. Like most say, lag is defently over rated. If you went with the smaller AR, I would be willing to bet you'll be kicking yourself down the road for not going with the larger. Unless your setting up an auto x car, go with the .63.

Years back when I swapped to an evoIII from stock, I was worried about lag being to much & thinking the evoIII was the max I could handle. Well I couldn't have been happier with the evoIII & didn't even really notice much additional lag. Since then my current turbo adds ~700rpms in spool vs the evoIII & I think its a great, daily driven street turbo. There's no way I'd trade the mid/top end of this turbo to gain a couple hundred rpms in spool & I do have to deal with alot of heavy traffic daily.