geoguy1369

iTrader: (2)

Hey guys im considering going to a on3 76mm non bb. Right now I have a hx55 which is a bit laggy with its 9xmm exhaust wheel. Its a stock 4.8 with 317 heads and a 4l80 with a stock converter. Any idea on what type of spool time it would have with the 76mm???

LT1RAY

iTrader: (21)

Stock cam? The real problem is the super low compression. A smaller exhaust wheel which will help some.

HX55 specs:
Compressor inducer - 65mm
Compressor exducer - 98mm

Turbine inducer is - 86mm
Turbine exducer is - 72mm

geoguy1369

iTrader: (2)

It does have a ls6 cam and some light porting on the exhaust ports. Otherwise stock.thats why I was thinking the .81 a/r housing because I think that was the smallest they offered.

LT1PWRD

iTrader: (2)

Don't those HX55's have a large exh AR? With a 4.8 and low comp, a 2" hotside, a little more stall and a .81-.96 would spool much quicker. Matt aka Denmah has done great with his 4.8 and on3 76. Read through Fairmont 3.0

LS1NOVA

iTrader: (12)

Get the compression back up.

geoguy1369

iTrader: (2)

The compression is fine. Yes its low but it is also a street car. I will make up the power with a little ectra boost. I just need to try to get it in quicker thats why I would swap turbo.

Gonoma

iTrader: (15)

A street car wants more compression...

LS1NOVA

iTrader: (12)

and a converter...

Forcefed86

iTrader: (4)

317s on a 4.8 is not "super low" compression. Compression isn't the problem IMO. A full point of compression is worth about 4% of your total power NA. Thats around 10HP on a 4.8. Not a game changer! Though the extra boost you can run coupled with a better flowing 317 head will more than make up for the compression drop.

HX55 can come with 20+cm housings. Thats like a 1.6x AR.

Need to give us more information than "a bit laggy". When do you start seeing boost? Full boost? How much boost do you run? How large is your hotside? current AR housing? Fuel used? Have you checked for boost/exhaust leaks?

I wouldn't run a .81AR housing.

geoguy1369

iTrader: (2)

I was just looking for a general answer for a stock motor and auto. But im on 93 gas. Front mount setup with air to air. Motor is 01 4.8 with ls6 cam and some springs. 317 with light exhaust work. Stock intake............ caris about 3200lb. 3.27 rear gear. Turbo does not say on it what size exhaust housing but look wise looks in the 1.5 range. It is about the same size as a ebay gt45.

geoguy1369

iTrader: (2)

Sorry forgot 12psi by 5k in first. No leaks.

Forcefed86

iTrader: (4)

There aren't general answers for what your asking without better info given on your part. An ebay gt45 doesn't have a 1.5 ar housing (it's 1.05). You can't judge an AR size by external dimensions. Any real holset will have the housing stamped. Unfortunately some are stamped on the inlet of the scroll or worn away. You gave a lot of info, but didn’t answer most of the questions asked. Get some real answers and someone may be able to give real help. Otherwise you get one sentence BS answers given by people who don't even know the basics of your setup.

(edited after you posted again)

Is 12lbs all you run? Where do you redline. When do you start making boost?

geoguy1369

iTrader: (2)

It is actually simple I was wanting to know as a stock 4.8 and stock converter even 4l60 what spool times people are seeing with the on3 76mm. Im not asking on my specific setup. That should be simple enough

Forcefed86

iTrader: (4)

Its really not. Best of luck to you though.

sparkwirez06

iTrader: (18)

I think the stock 80e converter stalls at 12-1500 rpms. with a first gear ratio of 2.2 on the 80e transmission, would make it difficult to spool.

geoguy1369

iTrader: (2)

I messaged on3 and they claim with a76mm in a stock 4.8 truck it starts boost in the 2k range and full boost inthe 3k range. So I figure ill give it a try. The holset is nice but would be alot better if 6.0 or big stall.

Gotit4cheap16

iTrader: (3)

Any number updates and ppowe it made?