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So I bought an on3 kit for my 5th gen camaro. Bought this kit because it's the only kit I found with it's turbo placement so I can run a 4 inch hood exit down-pipe to help with back pressure issues.. The two big downsides I hear about this kit is blowing gaskets and having other issues due to huge back pressure with the small on3 7875 and with the small 3" down-pipe running out to the back.
The problem is you can not fit an s475 type turbo because of space issues. If I could find a good flowing turbo that's not much bigger then the 7875 but with good flow and a 4" hood exit I wonder if I could get around the back pressure issues and still make good power? Buddy has recommended either the gen3 VSracing 7875 with 4" exit on 1.25 ar or possibly a precision 7675 gen2?
A good friend of mine with a 2011 SS (416 cubed, big N/A cam), seeing how well my PT7675 turbo'd 5.3 in my 96 z27 performed, decided to go to the ON3 Turbo setup w/o telling me. If I'd have known he was getting that turbo, I would've told him to not get it because the turbine is too small for that big of an engine and cam. But, what was done was done. Like you suggested, it was cramped, needed header retightening often, header gaskets constantly leaking (because of the back pressure), it cooked his power steering box/lines too. It would get into boost near immediately but felt like if flattened out early. Not to say it didn't provide fun at a stoplight, but blasts on the freeway were where you felt it running out of steam as the back pressure built. I discussed with him going to a bigger turbo turbine housing, something that would fit his displacement and cam but he didn't want to mess with it. He found a kid in NJ with a pro-charger and they swapped , even. No money changing hands. After we peeled the Turbo kit off and installed the Pro-Charger, he took it to Jannetys and had it dyno tuned. Got 732 rwhp out of it, so he's happy. The NJ kid put the Turbo kit on his car(98 - 02 Fbody w/LS1) , was careless about the tune/PSI and popped his engine within a couple of weeks.
What are your hp goals for the car? What engine / displacement? What supporting mods eg fueling, sbe or gapped rings, cam and springs etc. without this information it’s tough for anyone to recommend a turbo for you.
As far as reliability of the on3 kit with the 7875, I’ve had no issues with my setup (forged bottom end 5.3 with meth) and put down 706 whp on Slowhawk’s mustang dyno. That’s while retaining air conditioning.
Comp Turbo makes a 7884 turbo with a similar foot print as a 7875 iirc.
Its still going to choke early with all those cubes though.
That little 3" intercooler isn't going to serve you very well either.
Sell it and buy a procharger or something designed around a borg frame, you'll be happier in the long run.
What are your hp goals for the car? What engine / displacement? What supporting mods eg fueling, sbe or gapped rings, cam and springs etc. without this information it’s tough for anyone to recommend a turbo for you.
As far as reliability of the on3 kit with the 7875, I’ve had no issues with my setup (forged bottom end 5.3 with meth) and put down 706 whp on Slowhawk’s mustang dyno. That’s while retaining air conditioning.
Car is a 12 ZL1. 6.2 LSA engine all stock internally, with 9.0-1 comp ratio. Car is on e85 with ZL1 pump + Aux pump that comes on with hobs switch set at 4psi. supposed to be good for 900rwhp on e85.
Originally Posted by The ******
Comp Turbo makes a 7884 turbo with a similar foot print as a 7875 iirc.
Its still going to choke early with all those cubes though.
That little 3" intercooler isn't going to serve you very well either.
Sell it and buy a procharger or something designed around a borg frame, you'll be happier in the long run.
I did the uprgrade to the 4" intercooler. I will either keep my current setup (Kong 2650, Afco hx/fans, reinforced brick) or go to the turbo setup. I have had turbo cars before and get sucked in every time I run in my buddy's turbo 9 sec truck to go back turbo again. My car currently probably runs 10.6ish@130 on this setup so I probably could do pulley and open up exhaust and go pretty fast, but I love the way the turbo pulls compared to a s/c setup.
All that said and the info I have I probably can't do a 7875 and get to the 140mph range on the 6.2 so I will probably get something in the s475-s480 range and look into making it fit.
Car is a 12 ZL1. 6.2 LSA engine all stock internally, with 9.0-1 comp ratio. Car is on e85 with ZL1 pump + Aux pump that comes on with hobs switch set at 4psi. supposed to be good for 900rwhp on e85.
I did the uprgrade to the 4" intercooler. I will either keep my current setup (Kong 2650, Afco hx/fans, reinforced brick) or go to the turbo setup. I have had turbo cars before and get sucked in every time I run in my buddy's turbo 9 sec truck to go back turbo again. My car currently probably runs 10.6ish@130 on this setup so I probably could do pulley and open up exhaust and go pretty fast, but I love the way the turbo pulls compared to a s/c setup.
All that said and the info I have I probably can't do a 7875 and get to the 140mph range on the 6.2 so I will probably get something in the s475-s480 range and look into making it fit.
I think that's your best bet but if you go with a borg I'd do a completely divided hotside, most if not all borg turbines are twin scroll which is definitely something you want to take advantage of.
My car has a little 5.7 with a billet S484 and it lights off really quickly, my old merged T4 7875 was actually felt slower spooling.
Get as big a turbine as you can because 6.2L is a lot of cubes for a single unit, I'd seriously consider twins if you wanna eclipse 900whp easily.
Even my S484 would be more optimal on a smaller 5.3.
Something with a 106mm turbine might be your cup of tea but you also might **** at the price lol.
I think that's your best bet but if you go with a borg I'd do a completely divided hotside, most if not all borg turbines are twin scroll which is definitely something you want to take advantage of.
My car has a little 5.7 with a billet S484 and it lights off really quickly, my old merged T4 7875 was actually felt slower spooling.
Get as big a turbine as you can because 6.2L is a lot of cubes for a single unit, I'd seriously consider twins if you wanna eclipse 900whp easily.
Even my S484 would be more optimal on a smaller 5.3.
Something with a 106mm turbine might be your cup of tea but you also might **** at the price lol.
Well it looks like s480 doesn't fit under the hood. Is this the comp turbo you were referring to? Comp 7880?
I dont see a medium single being able to handle the exhaust flow at all. I have twin 68mm turbines and they are still 2:1 back pressure at 25PSI of boost.
That's the one, the 80mm turbine is still way too small for what you're doing but given the parameters you wanna work with I don't see another option.
I don't see it making anywhere near as much power as the Kong blower either but maybe I'll be wrong.
Yea I agree it's looking like I find a way to make an s480 work or nothing...
look at some old John doc videos on YT he has a precision 8891 shoved in the front of his street driven 5th gen. That’s dimensionally way bigger than a s400 borg. I’ve had both on my TBSS.
Are they physically smaller then the s480 though? And if so by how much? If anybody has dimensions on both that would be greatly appreciated
VSR 7875 is smaller than an S480, its basically same size as your On3 78. The Next Gen VSR 7875 is about $100 cheaper and a bit smaller (3" compressor outlet) than the Gen 3 which has a flanged 3.5" outlet, both have same 1.25 turbine housings with 4" outlets. I've run the VSR 7875 with the huron speed 5th gen kit, easily supports 9 second power.
VSR 7875 is smaller than an S480, its basically same size as your On3 78. The Next Gen VSR 7875 is about $100 cheaper and a bit smaller (3" compressor outlet) than the Gen 3 which has a flanged 3.5" outlet, both have same 1.25 turbine housings with 4" outlets. I've run the VSR 7875 with the huron speed 5th gen kit, easily supports 9 second power.
So you are saying this Gen3 VSR 7875 with the 4" outlet on 1.25 AR would get me in the 9's in a stock weight 5th gen? How about 140mph traps?
I havent run the Gen3, I ran the original with a .96 and 3.5" exhaust on a G8, same basic chassis but heavier than a 5th gen. Believe my best was 9.6@144.9 MPH on that turbo before switching to a larger unit.
I havent run the Gen3, I ran the original with a .96 and 3.5" exhaust on a G8, same basic chassis but heavier than a 5th gen. Believe my best was 9.6@144.9 MPH on that turbo before switching to a larger unit.
What drove the change to the larger unit?
9.6 is pretty respectable for a little 7875 in a full weight G8.
I'd imagine it spooled up quick, made a boat load of torque and kept the rpm reasonable?
What drove the change to the larger unit?
9.6 is pretty respectable for a little 7875 in a full weight G8.
I'd imagine it spooled up quick, made a boat load of torque and kept the rpm reasonable?
Because I’m never satisfied. It did spool quick, almost too quick for the street. Not sure what it made for tq, shifted 7500’ish.
02-21-2021, 11:00 PM
Best flowing compact turbo for 5th g on3 kit? 
