Turbo 427 ls suggestions
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Turbo 427 ls suggestions I'm doing a dart 427 considering a single turbo I'm wanting to push around 850 crank hp what compression ratio would I want? And what size turbo would spool up at a low rpm as it's in a lifted 4x4 setup probably going with a 227/236 115 cam
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Typically you’d want lower static with higher boost. It’s simple physics. More flow is simply better. This may be my next build, albeit I’ll be going the procharged way, simply because it provides cooler IAT’s. Better for pump gas IMO, when you want to keep it streetable with a ton of power on tap.
For compression I’d go for 8 up to 9 SCR. Personally I’d go maybe even lower. 7.5 may even be reasonable if you really want to crank the boost up on the top end. Keep in mind that with any centrifugal supercharger, including turbos, it’s going to produce next to nothing on the bottom end. So getting off the line may suffer, a little. Also keep in mind though that this may actually be beneficial for traction and require less hardware, but still make gobs of power up top.
I’m not really a fan of the argument that low SCR is a bad idea because of off the line power. Most engines spool pretty damn fast, so losing a few tenths of a second of acceleration to your max boost isn’t much of an argument to me when you can add in power on the top because of the low SCR.
Lots of success stories out there though involve between 8-9 SCR, but like I said, physics are simple in this. Best bet is as low as possible with as much boost as possible. This keeps the fuel safe and makes tons of power.
For the turbo, it will depend entirely on your SCR selection. If you go low, the go big on the turbo. You can even do a sequential setup if you have room to boost the boost lol. That kills the lag, and in that case I’d doubt you’d feel sluggish off the line, even with SCR in the 7’s.
For compression I’d go for 8 up to 9 SCR. Personally I’d go maybe even lower. 7.5 may even be reasonable if you really want to crank the boost up on the top end. Keep in mind that with any centrifugal supercharger, including turbos, it’s going to produce next to nothing on the bottom end. So getting off the line may suffer, a little. Also keep in mind though that this may actually be beneficial for traction and require less hardware, but still make gobs of power up top.
I’m not really a fan of the argument that low SCR is a bad idea because of off the line power. Most engines spool pretty damn fast, so losing a few tenths of a second of acceleration to your max boost isn’t much of an argument to me when you can add in power on the top because of the low SCR.
Lots of success stories out there though involve between 8-9 SCR, but like I said, physics are simple in this. Best bet is as low as possible with as much boost as possible. This keeps the fuel safe and makes tons of power.
For the turbo, it will depend entirely on your SCR selection. If you go low, the go big on the turbo. You can even do a sequential setup if you have room to boost the boost lol. That kills the lag, and in that case I’d doubt you’d feel sluggish off the line, even with SCR in the 7’s.
Thread Starter
Teching In
Joined: Apr 2021
Posts: 15
Likes: 2
Typically you’d want lower static with higher boost. It’s simple physics. More flow is simply better. This may be my next build, albeit I’ll be going the procharged way, simply because it provides cooler IAT’s. Better for pump gas IMO, when you want to keep it streetable with a ton of power on tap.
For compression I’d go for 8 up to 9 SCR. Personally I’d go maybe even lower. 7.5 may even be reasonable if you really want to crank the boost up on the top end. Keep in mind that with any centrifugal supercharger, including turbos, it’s going to produce next to nothing on the bottom end. So getting off the line may suffer, a little. Also keep in mind though that this may actually be beneficial for traction and require less hardware, but still make gobs of power up top.
I’m not really a fan of the argument that low SCR is a bad idea because of off the line power. Most engines spool pretty damn fast, so losing a few tenths of a second of acceleration to your max boost isn’t much of an argument to me when you can add in power on the top because of the low SCR.
Lots of success stories out there though involve between 8-9 SCR, but like I said, physics are simple in this. Best bet is as low as possible with as much boost as possible. This keeps the fuel safe and makes tons of power.
For the turbo, it will depend entirely on your SCR selecti on. If you go low, the go big on the turbo. You can even do a sequential setup if you have room to boost the boost lol. That kills the lag, and in that case I’d doubt you’d feel sluggish off the line, even with SCR in the 7’s.
For compression I’d go for 8 up to 9 SCR. Personally I’d go maybe even lower. 7.5 may even be reasonable if you really want to crank the boost up on the top end. Keep in mind that with any centrifugal supercharger, including turbos, it’s going to produce next to nothing on the bottom end. So getting off the line may suffer, a little. Also keep in mind though that this may actually be beneficial for traction and require less hardware, but still make gobs of power up top.
I’m not really a fan of the argument that low SCR is a bad idea because of off the line power. Most engines spool pretty damn fast, so losing a few tenths of a second of acceleration to your max boost isn’t much of an argument to me when you can add in power on the top because of the low SCR.
Lots of success stories out there though involve between 8-9 SCR, but like I said, physics are simple in this. Best bet is as low as possible with as much boost as possible. This keeps the fuel safe and makes tons of power.
For the turbo, it will depend entirely on your SCR selecti on. If you go low, the go big on the turbo. You can even do a sequential setup if you have room to boost the boost lol. That kills the lag, and in that case I’d doubt you’d feel sluggish off the line, even with SCR in the 7’s.
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From: Virginia
Turbos and pro chargers are both centrifugal. One uses a belt, the other uses exhaust. Same same in concept of operation. I think you are confusing positive displacement with centrifugal. PD blowers are “on” all the time. Centrifugal need RPM to make boost. The main difference is the HP and TQ curves. Centrifugal will actually be a curve and respond to RPM. PD blowers are pretty much a straight line right across the top making the same boost all the time where RPM is basically irrelevant.
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From: Virginia
Take some time and watch this. It explains everything. Might help you in making choices for your build.
https://m.youtube.com/watch?v=ZpBrrc...ature=youtu.be
https://m.youtube.com/watch?v=ZpBrrc...ature=youtu.be
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Joined: Mar 2013
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Typically you’d want lower static with higher boost. It’s simple physics. More flow is simply better. This may be my next build, albeit I’ll be going the procharged way, simply because it provides cooler IAT’s. Better for pump gas IMO, when you want to keep it streetable with a ton of power on tap.
For compression I’d go for 8 up to 9 SCR. Personally I’d go maybe even lower. 7.5 may even be reasonable if you really want to crank the boost up on the top end. Keep in mind that with any centrifugal supercharger, including turbos, it’s going to produce next to nothing on the bottom end. So getting off the line may suffer, a little. Also keep in mind though that this may actually be beneficial for traction and require less hardware, but still make gobs of power up top.
I’m not really a fan of the argument that low SCR is a bad idea because of off the line power. Most engines spool pretty damn fast, so losing a few tenths of a second of acceleration to your max boost isn’t much of an argument to me when you can add in power on the top because of the low SCR.
Lots of success stories out there though involve between 8-9 SCR, but like I said, physics are simple in this. Best bet is as low as possible with as much boost as possible. This keeps the fuel safe and makes tons of power.
For the turbo, it will depend entirely on your SCR selection. If you go low, the go big on the turbo. You can even do a sequential setup if you have room to boost the boost lol. That kills the lag, and in that case I’d doubt you’d feel sluggish off the line, even with SCR in the 7’s.
For compression I’d go for 8 up to 9 SCR. Personally I’d go maybe even lower. 7.5 may even be reasonable if you really want to crank the boost up on the top end. Keep in mind that with any centrifugal supercharger, including turbos, it’s going to produce next to nothing on the bottom end. So getting off the line may suffer, a little. Also keep in mind though that this may actually be beneficial for traction and require less hardware, but still make gobs of power up top.
I’m not really a fan of the argument that low SCR is a bad idea because of off the line power. Most engines spool pretty damn fast, so losing a few tenths of a second of acceleration to your max boost isn’t much of an argument to me when you can add in power on the top because of the low SCR.
Lots of success stories out there though involve between 8-9 SCR, but like I said, physics are simple in this. Best bet is as low as possible with as much boost as possible. This keeps the fuel safe and makes tons of power.
For the turbo, it will depend entirely on your SCR selection. If you go low, the go big on the turbo. You can even do a sequential setup if you have room to boost the boost lol. That kills the lag, and in that case I’d doubt you’d feel sluggish off the line, even with SCR in the 7’s.
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Joined: Oct 2014
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From: Virginia
Yes, all of them are superchargers, and all do the same thing, which is compress air. They just vary in how they accomplish that. They even have electric ones now, which is interesting.
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So a Dart 427 and a turbo setup and all you want is 850 crank? That's about the easiest thing in the world to accomplish and the combo all depends on what fuel you are going to run, what you are doing with it, etc. I see where you said it's in a lifted 4x4 truck but what are you going to do with it?
And a turbo setup is NOTHING like a centrifugal supercharger.
And a turbo setup is NOTHING like a centrifugal supercharger.
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Verdad Gallardo TECH Fanatic
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From: Virginia
So a Dart 427 and a turbo setup and all you want is 850 crank? That's about the easiest thing in the world to accomplish and the combo all depends on what fuel you are going to run, what you are doing with it, etc. I see where you said it's in a lifted 4x4 truck but what are you going to do with it?
And a turbo setup is NOTHING like a centrifugal supercharger.
And a turbo setup is NOTHING like a centrifugal supercharger.
I’d add in the huge thing on the turbo is nothing slows it down like a belt driven one, meaning overboost into off throttle transitions are definitely different. The need for blowoff is definitely more relevant and noticeable. Basically, there is lag on all transitions for turbos.
I think the coolest part between either of them is adjustable boost. Someday when I grow up I’ll have enough money to afford a good setup with these features lol. Damn bills are getting in the way of that.
And to the OP, I don’t know if you mentioned fuel or not, but the SCR’s I mentioned are aimed at 93 pump. You can DEFINITELY go higher if you are running something like pure alcohol, or E85, etc. These fuels can take A LOT more compression and boost. I don’t know if that’s your plan, but I think from your goals pump seems to be what you’re aiming for.
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From: Virginia
I'm sorry, but I still disagree. High speed impellers to throw particles is the same concept of operation. 50,000+ RPM to make high speed low pressure air, then diffused into high pressure low speed air, which is then sent to the intake or intercooled, etc, is the same concept. The primary difference is how the impeller is spun. I'm not seeing how these are different in WHY they make boost. HOW they do it is obviously different, yes.
I never said PD blowers were adjustable. But Procharger does have a centri blower that is:
https://www.procharger.com/procharge...1_supercharger
BOV's are obviously needed on centri as well. Didn't say they weren't. But I've had a few scares running twins where the boost hung and it got pretty lean, and hot. It is self correcting I guess, I just prefer the safety of a BOV in that setup. I guess you could say it was indeed hard on the turbos. On the centris, only played with a few, didn't see hangs like that though. I'm not the world expert here, just speaking from a few personal examples and my opinion on it.
I never said PD blowers were adjustable. But Procharger does have a centri blower that is:
https://www.procharger.com/procharge...1_supercharger
BOV's are obviously needed on centri as well. Didn't say they weren't. But I've had a few scares running twins where the boost hung and it got pretty lean, and hot. It is self correcting I guess, I just prefer the safety of a BOV in that setup. I guess you could say it was indeed hard on the turbos. On the centris, only played with a few, didn't see hangs like that though. I'm not the world expert here, just speaking from a few personal examples and my opinion on it.
I'm sorry, but I still disagree. High speed impellers to throw particles is the same concept of operation. 50,000+ RPM to make high speed low pressure air, then diffused into high pressure low speed air, which is then sent to the intake or intercooled, etc, is the same concept.
I never said PD blowers were adjustable. But Procharger does have a centri blower that is:
https://www.procharger.com/procharge...1_supercharger
https://www.procharger.com/procharge...1_supercharger
But I've had a few scares running twins where the boost hung and it got pretty lean, and hot. It is self correcting I guess, I just prefer the safety of a BOV in that setup. I guess you could say it was indeed hard on the turbos. On the centris, only played with a few, didn't see hangs like that though.
But you said that turbos and prochargers are both centrifugal and have the same concept of operation, that is not even remotely true. The power/torque curves of a turbo are WAY different from a procharger setup and do not operate the same at all.
What? Overboost into off throttle transitions? And technically if you didn't want to run a blowoff valve on a turbo setup you don't need one although it's going to take it's toll on the turbo itself, but try doing that on a procharger and you will blow **** apart.
Adjustable boost on a procharger or PD blower? No. And using a BOV as a pseudo wastegate to regulate boost just doesn't work efficiency nor does it work well on a procharger setup, been there and done that.
What? Overboost into off throttle transitions? And technically if you didn't want to run a blowoff valve on a turbo setup you don't need one although it's going to take it's toll on the turbo itself, but try doing that on a procharger and you will blow **** apart.
Adjustable boost on a procharger or PD blower? No. And using a BOV as a pseudo wastegate to regulate boost just doesn't work efficiency nor does it work well on a procharger setup, been there and done that.
I'm starting to think you don't understand what is being said either, there is a clear lack of understanding here about how this stuff works. One of my big pet peeves is people making stuff up just to add to a conversation.
Well one huge difference is a centri blower is constantly moving the same amount of air at every RPM point and a turbo doesn't work that way, at all. Turbos need load to produce airflow, and they are also torque monsters compared to a centri blower because they will hit their desired boost level well before peak engine RPM and hold it through the powerband.
I said this same thing recently that turbos need load and another member on this forum said I didn't know what I was talking about.
No explanation, facts or reasoning presented when I pressed, just BS.
Theory and practice seem to be quite different in the world of FI I've noticed.
I said this same thing recently that turbos need load and another member on this forum said I didn't know what I was talking about.
No explanation, facts or reasoning presented when I pressed, just BS.
Theory and practice seem to be quite different in the world of FI I've noticed.
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From: Virginia
To clarify, the point was that both turbos and centrifugal blowers use centrifugal force to produce boost. Basically throwing air particles at high speed off of an impeller.
Yes, they are different. Yes a turbo requires load to do this. I am not disputing that they operate differently. No ****, they obviously are very different. But on the physics level, when talking strictly airflow, they are both centrifugal in how boost is created. They create different curves, but both are similar from the centrifugal/turbo when contrasted with PD. They both produce curves. PD doesn’t, since PSI is mostly fixed, but it does vary slightly. Also, PD blowers don’t use centrifugal force. They trap air on the output side, so it’s not thrown down a tube like centrifugal and turbos do, which both use centrifugal force to do so, and then use Bernoulli’s principle to pressurize the air.
Yep, totally tracking they both produce completely different results, and operate differently. They’re absolutely different. Yes. How the air actually gets pressurized, or moved, not so different. I think of a centrifugal blower as basically being a belt fed turbo. That’s basically what it is.
Yes, they are different. Yes a turbo requires load to do this. I am not disputing that they operate differently. No ****, they obviously are very different. But on the physics level, when talking strictly airflow, they are both centrifugal in how boost is created. They create different curves, but both are similar from the centrifugal/turbo when contrasted with PD. They both produce curves. PD doesn’t, since PSI is mostly fixed, but it does vary slightly. Also, PD blowers don’t use centrifugal force. They trap air on the output side, so it’s not thrown down a tube like centrifugal and turbos do, which both use centrifugal force to do so, and then use Bernoulli’s principle to pressurize the air.
Yep, totally tracking they both produce completely different results, and operate differently. They’re absolutely different. Yes. How the air actually gets pressurized, or moved, not so different. I think of a centrifugal blower as basically being a belt fed turbo. That’s basically what it is.
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Well one huge difference is a centri blower is constantly moving the same amount of air at every RPM point and a turbo doesn't work that way, at all. Turbos need load to produce airflow, and they are also torque monsters compared to a centri blower because they will hit their desired boost level well before peak engine RPM and hold it through the powerband.
I said this same thing recently that turbos need load and another member on this forum said I didn't know what I was talking about.
No explanation, facts or reasoning presented when I pressed, just BS.
Theory and practice seem to be quite different in the world of FI I've noticed.
I said this same thing recently that turbos need load and another member on this forum said I didn't know what I was talking about.
No explanation, facts or reasoning presented when I pressed, just BS.
Theory and practice seem to be quite different in the world of FI I've noticed.
So your supposed pearl of wisdom is turbo lag exists, amazing, who knew.
Not wasting anymore time with someone who's contribution is "turbo lag is real".
