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From what I've been reading here lately, even the VS S480 clone is not too big on a 4.8, and it's a T6 flanged 88/96 twin scroll huge turbo.. I'm really astonished to see the turbine sizes folks here are running.
A S476 or S480 would fit in the same space a 7675 would? I thought they were much larger?
They are a lot bigger, especially the compressor housing.
The unit you linked is based on a Borg S4xx style unit which will be quite a bit larger then the PT76 you have now.
If you want the same physical footprint of what you have now, look at the VS Next Gen billet 7875. https://turbo4less.com/product/vsr-n...n-7875-billet/
Performance would be pretty close to a billet precision unit of the same size.
Forced Inductions S476 with a 88/96 turbine and a 1.10 T4 housing. Capable of 1200whp maxed out.
Why limit a 383 to a 1.10 AR?
Originally Posted by Shownomercy
Worried 75mm turbine is too small on a 383ci motor.
It is! Even an 88/96 turbine is too small for optimal results. You can get a flange adapter for cheap (or weld a new one on) to open up your turbo choices.
It is! Even an 88/96 turbine is too small for optimal results. You can get a flange adapter for cheap (or weld a new one on) to open up your turbo choices.
Hey Slow Sedan, what's been your experience with using flange adapters more accurately T4 to T6?
I've got a buddy with an 4th gen f-body running a merged T4 setup, he won a brand new VS Racing 85/96 T6 unit in a raffle recently and is looking at welding on a T6 plate to get going but is worried about responsiveness.
Will the merged T4 hotside to the T6 divided housing make spooling slower than normal?
Is there any advice you can offer?
Here's my VS Racing S480 billet wheel clone. I opted for the 3.0" slip fit outlet.
I'm making a sheet metal heat shield to reduce radiated heat from the turbine. The turbo blanket i bought is too bulky with the turbo mounted in this position.
Hey Slow Sedan, what's been your experience with using flange adapters more accurately T4 to T6?
I've got a buddy with an 4th gen f-body running a merged T4 setup, he won a brand new VS Racing 85/96 T6 unit in a raffle recently and is looking at welding on a T6 plate to get going but is worried about responsiveness.
Will the merged T4 hotside to the T6 divided housing make spooling slower than normal?
Is there any advice you can offer?
Adapters have been fine for me, assuming you don't have abnormally small pipes leading up to it but thats not generally the case. I wouldn't be concerned at all, allow the engine to breath a bit better. I doubt you'll notice much of a change in spool and just make more power.
I'm not hesitant at all on moving things, it often makes the car easier to work on. Its often quicker to cut the flange off and weld a new one than fiddle around with what's in the way. But anything you can do to get a larger turbine on there is a win.
I wonder if a hybrid turbo isn't the answer, depends on how much you want to spend as well?
A local guy has a 4th gen f-body w/ a 408" LS / T56 trans and the turbo is mounted down where the AC compressor is usually located next to the engine.
The turbo is a precision unit with an 80mm compressor / 96mm turbine T4 flange but physically isn't much bigger if at all then a Turbonetics T7875.
Turbo Technology here in Tacoma, WA built the kit and supplied the turbo, car made just over 1,000whp on race gas on a soft tune so it makes power.
I'd imagine you'd have to inquire with PTE directly since its unlikely that's something they'll have sitting on the shelf.
Brace yourself as well because it probably won't be cheap but when weighed against completely changing your setup it might make sense.
I’ve not seen much gain with say billet wheel 7675 vs old 76gts cast wheel turbos. Guys were going 140-150 with the gts many moons ago. Anyone have any back to back data or tests? It always seems to be that the turbine is the limit on a ls v8. Pte’s gen 2 turbine might help or maybe the newer comp turbine but not much info on those.
I don't want to spend PT money again thats for sure
Looking for a PT88 copy from VSR or similar.
I ran on3's 88/84 T4 way back, it didnt offer much of a gain over the 76 roughly ~2 tenths and a bit slower spool. I'd much rather have a 76 with the 88/96 turbine.
Completely understand that lol.
I'd say the VSR Next Gen billet 7875 is your best bet.
I'd be shocked if the VSR made much (if any) more power than the Precision. I believe someone previously tested the 7875 vs the PT7675 on the same car and it was down ~50whp, so even if the next gen is 50whp better, its an even race. Once you get close to 800whp the 75mm turbine is just hard to get around, sure you can lean on them and get a little more but its more beneficial to get a larger turbo.
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PT76 Upgrade 
