347 stroker turbo size?

I run just such a cam in one of my cars, and a more supercharger style split duration cam in the other. I prefer the former. Hard to get into detailed measurements, because the displacement is 331 vs. 363 and the static CR is 1 point difference. But I can tell you the lower compression reverse split is a lot more street friendly when I tune them.
 
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You know, I wouldn't even do the thinking on that one if I were you... you've got enough money in the build that you can spare < $100 for an expert. I just called Ed Curtis and asked him to do the cam. He did the reverse split one.
 
Ok, I was assuming that based on the power you were talking, but wanted to make sure. I think 10:1 compression is a pretty rough starting point for a street car with a turbo, and it made me start wondering about your whole setup.

Isn't the 7875 a turbonetics? No personal experience here on that one. Maybe it's worth more power, but is it even a precision turbo? Might not be worth the quality difference. I'll leave that to your research. If you're really shooting for 700-800, then you won't be using up the 7675 precision turbo.
On3 offers a 78/75 but I don't think I need it
 
I'm an On3 hater, so I'll refrain from advising on that one. Figure out the source of the turbo. On3 subcontracts everything to the lowest bidders. The only turbo I know of theirs that I liked was when they used master power T70s. I have no idea on the 7875. I thought you were referencing the Turbonetics one.
 
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Those are good questions that I don't think I can answer. I think the spooling is not going to be an issue, regardless. I have a lot of back pressure on that car. However, those are both far more a function of the turbo than the cam. Proper turbo sizing is hard, because companies don't release compressor AND turbine maps. So, we're left with trial and error as a community. We see what's worked for other people, and we pick what we think is best for us. But, turbo sizing properly can make a turbo spool wherever you want, make any power you want, and have less backpressure than boost. When you get close, all of these things become trade offs with each other. We all want a turbo that spools at 2500 rpm, makes 1000+ hp, and has 0 back pressure. But, I'll settle for a turbo that makes the power I'm shooting for, spools fast enough that it's not an issue, and doesn't have back pressure that limits the power or hurts the motor. I've accomplished all of those things with the GTS 76 in one car and the GT4202R (same compressor wheel, bigger turbine housing & wheel) in the other.

I think the cam can maybe make a couple hundred RPM difference, 2 digit power differences, and a WORLD of difference in driveability. My advice for a street car is let the turbo do the heavy lifting and get a nicely driveable cam. Beautiful thing about turbos is that you don't need a whole lot of cam. They actually do better without overlap. So power, torque, and streetability all come together in one.
 
Cold Side Details:

  • Anti Surge Compressor Cover
  • 4″ Inlet
  • 3.0″ Outlet
  • CNC Machined Billet Compressor Wheel
  • 1/8″npt Port For Boost Reference

Exhaust Side

  • 75mm Turbine
  • 3.0″ V-band Outlet
  • T-4 Flange
  • .96ar

what do you think? its a 76/75 but it has a 3in outlet instead of 2.5 like most. Doesn't have CBB. How do you think this will work for me as far as lag and back pressure? also longevity wise how do journal bearings compare to CBB
 
Are you keeping the 10:1 comp ratio?

1.10 a/r is the minimum I’d go with if you’re looking to make 700whp+. No reason to choke yourself out of the higher rpm range.

S475 with 1.10 housing would be my choice, But i’d Probably go e85 if I was looking at your c/r.
 
I think I'll never buy a chinese turbo, because whatever bearings it has, I wouldn't trust its longevity. Other than that, the specs look fine. Lag will be small, back pressure will be high. It will get the job done until it breaks. Journal vs. ball-bearings is not a longevity decision. It's a spooling & $$$ decision. Journal bearing turbos are what most OEM use. They spool slower and make the same power. Ask folks who've run that particular turbo about their experience with it, because I don't have any. I'd personally buy the precision, even at double the price. But, I wouldn't be looking at an On3 kit in the first place.
 
Are you keeping the 10:1 comp ratio?

1.10 a/r is the minimum I’d go with if you’re looking to make 700whp+. No reason to choke yourself out of the higher rpm range.

S475 with 1.10 housing would be my choice, But i’d Probably go e85 if I was looking at your c/r.
Yeah keeping the 10:1. Can't afford new heads or pistons. Looking to have a fun car again. Would the 1.10 cause too much lag?
 
What I know about turbos could be summed up on a 3x5 index card.

I know this though..

For every guy that hates a Chinee turbo or Chinee turbo kit, there are 20 guys using them.
For the price of every American turbocharger, you can buy a Chinee turbocharger 3 or 4 times.

I had an American twin scroll turbo recommended by a very knowledgeable turbo rebuilder.
It took time to get into boost.
I sold that turbo and bought a Chinee mono scroll turbo for a 1/3rd the price.
It gets into boost instantly. it makes good power, and it sounds great.
How long it'll last is a YTD.
but...
However long that is.......
I can still buy two more and be at the same initial investment.

The only part of the Chinee equation that you cannot rely on based from my own experience is the Wastegate's. You cannot save money there. It's one thing to cheap out on a turbo, but the gate is what keeps the turbo in control. .you'll have to pony up for a good American or Australian unit(s). But be prepared for that one, especially if you buy a twin scroll turbo ( cause you'll have to buy two of them).
 
A/Rs of twin scroll turbos can't be compared directly to singles. They act like smaller single A/Rs.
Correct. That’s why you can go with a tad bigger a/r with a twin scroll. You may lose a bit of power at higher rpm, but you’ll have great mid range drivability. Realistically you won’t need super high boost numbers if already making 400+whp n/a to hit the 7-800hp you’re after, provided the rest of your induction setup is up to snuff.
 
Are you keeping the 10:1 comp ratio?

1.10 a/r is the minimum I’d go with if you’re looking to make 700whp+. No reason to choke yourself out of the higher rpm range.

S475 with 1.10 housing would be my choice, But i’d Probably go e85 if I was looking at your c/r.
What's your thoughts s475 T4 or T6 for my application? What size compressor and turbine? Again looking for fast spool without back pressure problems 5 speed car
Are you keeping the 10:1 comp ratio?

1.10 a/r is the minimum I’d go with if you’re looking to make 700whp+. No reason to choke yourself out of the higher rpm range.

S475 with 1.10 housing would be my choice, But i’d Probably go e85 if I was looking at your c/r.
 
Too far into the weeds. It's not going to matter much, though theoretically it should slow spool and inrease flow/max power, it will ultimately be insignificant. If you really want to get into this stuff, learn to read a compressor map. That is the technically correct way to size a turbo. But, I imagine you'll find the data out there lacking. At the end of the day, after learning all that stuff, I just ended up picking the same turbo that worked well for others' combos.

S475 is rated to 1k hp. PTE 7675 is rated to 1100hp. S480 to 1250hp. So, any will reach your goals.

Mike may be right about Chinese turbos. He's definitely right about getting quality wastegates. I guess we all do what we know and are comfortable with.
 
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What do you guys think about this PTE7675 with. 96 housing? Can also get with cast wheel for $500 less. Do feel a billet wheel or also the $900 option for cbb will make a huge difference in spool for me?
 

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Awesome street turbo. Spools fast, makes all the power you're asking for and more. The CBB might give you ~300 rpm quicker spool. You will build boost in the high 2k rpm range and reach full boost around 3500 give or take without CBB. You decide if your wallet can justify it for the price. I don't think a billet wheel does much that a cast doesn't.
 
Awesome street turbo. Spools fast, makes all the power you're asking for and more. The CBB might give you ~300 rpm quicker spool. You will build boost in the high 2k rpm range and reach full boost around 3500 give or take without CBB. You decide if your wallet can justify it for the price. I don't think a billet wheel does much that a cast doesn't.
Awesome. The offer up to a. 96 ar. Do u think that's enough for me or will I run into back pressure problems. And thank you by the way for helping me out. This has been great