Dr.Sep

Hey,

so I really did use the search function and looked at all the thread titles with either and/or both 6258 and 6758 (all 35 of them on 2 pages even) but didn't fully answer my question

background:
94 block, JE pistons, Manley rods, refreshed BP4W with heavier springs, skunk2 intake, 1000cc injectors, DW300 pump, 6 speed, E85/flex with Ms3
Street car only
Notoriously conservative dyno (usually closer to mustang than dynojet numbers) and altitude is no more than a couple hundred above sea

So I love my spool and I love it now (coming from a T2554 garrett from a CA18DET) so obviously the 6258 is winning already, but on e85 do you think 350 @ the wheels is obtainable without totally maxing out the turbo or if 350 is my goal, should I just live with a little less spool for the headroom/efficiency of the turbo?

I really think 350 with maybe a 375 kill map for highway pulls would be all I want out of it, especially because I don't want to consume 6 speeds regularly or drop the money into a BMW transmission swap, but at the same time I think I would be awfully disappointed if I built the car "right" (in my opinion anyways) and only got me a little above 300

thoughts? I truly respect the opinions here and appreciate any genuine guidance

Arca_ex

iTrader: (2)

In your research you should have found multiple people doing 400whp with the 6258 already so it's a no brainer.

Dr.Sep

I really didn't that had "6258" in the title, running e85 and on a conservative dyno, but thanks
I really tried to avoid this exact comment, spent at least an hour and half this morning trying to educate myself on this specifically, but hey -- I guess I asked for it coming here anyways.

Also, bold of you to assume I have a brain

andyfloyd

6258 will spool sooner obviously because its a smaller compressor wheel and Im sure you already know this. There is a popular youtuber who runs a 6258 and made 420whp on e85 on a dynojet with his 6258. Having said these things I would go bigger to the 6758 because it will spool a couple hundred rpm slower and youll want more power if you are like me. 6758 will have more legs to grow with you. If you truly dont wantmore than 350 then get the 6258 but at least in my case I always want more. My buddy has a 6758 on his sr20det and its spool is amazingly good FWIW.