LS6427

iTrader: (2)

Let me clarify.

My goal is a highway puller.....40-160mph....or so.....

Theres always talk about give and take with boost, nitrous and N/A set ups........

Usually to have great top end pull.....you give up some down low power. But really its not that bad when it comes down to it. The loss of down low power isn't like the car is a dog and cant beat a minivan in an 1/8th mile race.......its still going to be a terror down low.

What I don't want is one of those single turbo set ups that when you get into the throttle from a dig or slow roll on punch....it accelerates and takes off but the turbo is spooling up and then WACKS you hard out of nowhere and blows the tires off............

Zero lag down low and through the mid rpms probably wont happen without a big loss of top end hard pulling all the way to 160-170mph.......so I just want a smooth build-up of boost down low and through the mid rpms and a hard pull on the top end.

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LILHEMI

on a 390" motor? no. my billet 80mm with the same turbine is INSTANT spool on my 408 at 4300ft altitude. so the turbo i mentioned would be PERFECT for him.

LS6427

iTrader: (2)

I'll be at about 10.2:1 compression on E85 too, so that should help with low end spool.

S476 w/92mm wheel wont run out of steam way up top at 170mph....?

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LosLS2

Running out of steam is more about RPM than MPH.

LosLS2

What does instant spool mean to you?

LILHEMI

less than a second for transient response?

LS6427

iTrader: (2)

When I say run out of steam....I mean when a turbo is a little too small to keep feeding an engine and KEEP pulling hard up top and it starts to lose power....or flatten out...

I'm no expert about turbos and I have no interest in learning everything about them....air ratios, different wheel sizes, cases, covers, models......etc....

I want someone to tell me which is best for my needs and my combo, have my friend install the kit and turbo and then go pick my car up......then just maintain it.

.

LosLS2

Any turbo mentioned here will pull well past 160 mph if geared properly.

ddnspider

iTrader: (26)

Turbos only run out of steam when you're way off the efficiency map and they cannot flow the amount of air you're trying to move. Figure out how much air/power you want to make at how much boost and work backwards to the size turbo. A 76gts will move like 96 lb/min of air, more than enough to pull to 160mph and the smaller the turbine size the faster it'll spool.

LosLS2

When I say instant, I mean that when you hit it from a 4000 rpm roll, there is boost there waiting for you.

LILHEMI

i dont think i can hit 4000 rpm without making boost lol. i can hear my turbo spooling at part throttle at 2800+ rpm. if i stab it anywhere over 3500 its INSTANT. my turbo is a tad undersized for my motor and i was worried about that but john bewley cammed it for the turbo and its a hoot. big torque, big powerband and i never have to spin it over 6500.

LosLS2

OK, THAT's instant.

LilJohn

S400 with a billet 76mm or Billet 80mm with a 92mm turbine and a 1.10 T6 housing would be fine on this. The actual turbo matters the least when it comes to creating response, Tune, pipe sizing, camshaft can affect it moreso than the turbo itself.

LosLs2.... Dont forget... precision 7675... 75mm is the exducer of the turbine wheel and the 92mm of the borg is the inducer.... the 92mm turbine is only 10mm bigger than the 7675...92/85 versus 83/75.

Pro Stock John

iTrader: (34)

That cam and a 4.11 rear gear should feel stronger... So I think before I changed anything I'd share what the timing table looks like and confirm exactly what turbo and a/r you have.

ddnspider

iTrader: (26)

I promise, if he's running stock height tires with a 6 speed, those gears are hurting him. I had the same experience. Tuning will only get you so far. I would literally run out of RPM before the turbo would hit max boost. Switched to a 3.42 and not only would boost come on much harder and longer in each gear but I was also able to make MORE boost with no other changes.