Centrifugal S/C or Turbos

triple-s

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I went from a 2.6 kb to a F1a and dam did i love my procharger. I made more power with the same amount of boost on the f1a then I did with the kb. I didn't have all the heat soak either I used just run to the store down the street and I couldn't even touch the kb cause it was so freaking hot. Only downside was I had to launch my car above 4k to get the power quick when I street raced.
 

97WHITEVENOM

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Not quite sure why everyone keeps saying turbos are much easier on the motor. Cylinder pressure is the hardest thing on a motor, and with properly sized turbos they create more cylinder pressure than a centri blower for sure. Only thing that usually creates more cylinder pressure is nitrous.
 

11Sec_Lx

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Not quite sure why everyone keeps saying turbos are much easier on the motor. Cylinder pressure is the hardest thing on a motor, and with properly sized turbos they create more cylinder pressure than a centri blower for sure. Only thing that usually creates more cylinder pressure is nitrous.
Definitely some misinformation and outdated information in here. But then I thought, "what's for dinner?"

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9397SVTs

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Not quite sure why everyone keeps saying turbos are much easier on the motor. Cylinder pressure is the hardest thing on a motor, and with properly sized turbos they create more cylinder pressure than a centri blower for sure. Only thing that usually creates more cylinder pressure is nitrous.

All things being equal, the cylinder pressure is the same. How it's derived shouldn't matter.

The main difference is a turbo doesn't load the crank snout or introduce harmonics to the crankshaft. This is where a turbo is "easier" on an engine.

I could be wrong, but it makes sense to me.
 

Blk91stang

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All things being equal, the cylinder pressure is the same. How it's derived shouldn't matter.

The main difference is a turbo doesn't load the crank snout or introduce harmonics to the crankshaft. This is where a turbo is "easier" on an engine.

I could be wrong, but it makes sense to me.

That's what my engine builder said also. Nitrous and superchargers are tough on engines compared to a properly setup turbo.
 

JetmechF16

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I've had Roots/TS/TVS blowers, single turbo, twin turbo, and turbo diesel setups. Right now I have an F-1A that is just plain nuts, hits extremely hard and sounds like a 747 taxiing. It still has plenty more potential, gears and head/cam work would take it up a few more notches.
 

9397SVTs

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I had a friend that had an F1-A on a built engine. It was loud and obnoxious, but put a smile on your face. It made 780 RWHP. It was a fun toy, but I wouldn't want to drive it every day. It would get old and annoying.
 

95Cobra_Iowa

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On my 1995 cobra I have a 347 dart block and was running maximum impeller speed on a TI trim vortech. I mad 713 HP on 22.9lbs of boost on E85. Torque was great too with 347 cubic inches and it was a very predictable power band.

I was constantly fighting belt slip, partly because there's no good lower pulley setup for 1995 Cobras. So I finally bit the bullet and went single turbo. I changed camshafts to a turbo specific cam from a supercharger specific cam. (Both were from the same guy specified for street driving, a/c, power steering, etc).

I ended up with 723 hp, on 15.1 lbs of boost on 93 octane and more torque. The car is quieter, no whining blow off valve that prevents having conversations, the turbo quiets the exhaust, and I can turn the car up on C16 and it produces 945 HP and 950 torque.

The only downside is holding on when boost hits, where the supercharger was so linear and predictable it was easier to control wheel spin.
 

97WHITEVENOM

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All things being equal, the cylinder pressure is the same. How it's derived shouldn't matter.

The main difference is a turbo doesn't load the crank snout or introduce harmonics to the crankshaft. This is where a turbo is "easier" on an engine.

I could be wrong, but it makes sense to me.
Blowers do introduce harmonics and sometimes can be hard on the front main bearing. However...

Cylinder pressure for a properly sized turbo is not the same as it is for a blower. A centri blower that makes a peak of 10psi of boost, with no belt slip, and a properly sized blower, will make 10 psi of boost at redline... and less below redline, its just how centri blowers work.

With a properly sized turbo that isnt way too big for a combo, if it is set to make the same 10psi at redline it will almost always make more boost than a centri down low. In fact most properly size turbos will make full boost as low as peak torque and hold it to redline.

Peak torque IS peak cylinder pressure. Turbos almost always make way more torque than blowers for a given amount of boost.

Look no further than WRX/STIs... the ONLY way they get those motors to live to make 400hp+ is to absolutely kill the peak torque (cylinder pressure). They have to be tuned so that they kill timing/and boost down low and let it come in with RPM. If they dont they blow up ringlands left and right.
 

RedVenom48

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Blowers do introduce harmonics and sometimes can be hard on the front main bearing. However...

Cylinder pressure for a properly sized turbo is not the same as it is for a blower. A centri blower that makes a peak of 10psi of boost, with no belt slip, and a properly sized blower, will make 10 psi of boost at redline... and less below redline, its just how centri blowers work.

With a properly sized turbo that isnt way too big for a combo, if it is set to make the same 10psi at redline it will almost always make more boost than a centri down low. In fact most properly size turbos will make full boost as low as peak torque and hold it to redline.

Peak torque IS peak cylinder pressure. Turbos almost always make way more torque than blowers for a given amount of boost.

Look no further than WRX/STIs... the ONLY way they get those motors to live to make 400hp+ is to absolutely kill the peak torque (cylinder pressure). They have to be tuned so that they kill timing/and boost down low and let it come in with RPM. If they dont they blow up ringlands left and right.
You have no idea how many Subi guys have tried to tell me that their STI engine was the greatest engine to ever leave a factory on God's green earth. Its an impressive little engine, but they spend A LOT of cash to build them up.
 

Tunedprt91

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I ended up with 723 hp, on 15.1 lbs of boost on 93 octane and more torque. The car is quieter, no whining blow off valve that prevents having conversations, the turbo quiets the exhaust, and I can turn the car up on C16 and it produces 945 HP and 950 torque.

The only downside is holding on when boost hits.

Screenshot_20201122-124910~2.png
 

SecondhandSnake

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I've had Roots/TS/TVS blowers, single turbo, twin turbo, and turbo diesel setups. Right now I have an F-1A that is just plain nuts, hits extremely hard and sounds like a 747 taxiing. It still has plenty more potential, gears and head/cam work would take it up a few more notches.

Centris do sound really good. So much so that when I crossed paths with a stock bottom end 2V with an S trim my gut reaction was "wow that thing sounds bad- I better avoid it" even though on my low boost 93 tune I would have been making enough to scatter that engine into oblivion.

The only downside is holding on when boost hits, where the supercharger was so linear and predictable it was easier to control wheel spin.

Are you running anything to manage power for it? When a big turbo spools it can get real scary real quick. I used to know a guy with a big single Nissan that picked up over 500hp in the span of about 1000 RPM. No idea how he kept that thing straight without a boost controller. That's one thing I like about my combination- it spools early and keeps pulling, no sudden onrush of power to unsettle it.
 

95Cobra_Iowa

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Centris do sound really good. So much so that when I crossed paths with a stock bottom end 2V with an S trim my gut reaction was "wow that thing sounds bad- I better avoid it" even though on my low boost 93 tune I would have been making enough to scatter that engine into oblivion.



Are you running anything to manage power for it? When a big turbo spools it can get real scary real quick. I used to know a guy with a big single Nissan that picked up over 500hp in the span of about 1000 RPM. No idea how he kept that thing straight without a boost controller. That's one thing I like about my combination- it spools early and keeps pulling, no sudden onrush of power to unsettle it.

No power management. It is managed by a Holley EFI system, so I could if need be.

Here are both graphs. West700 is the e85 vortech, the other is the 7675 turbo.
 

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9397SVTs

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Blowers do introduce harmonics and sometimes can be hard on the front main bearing. However...

Cylinder pressure for a properly sized turbo is not the same as it is for a blower. A centri blower that makes a peak of 10psi of boost, with no belt slip, and a properly sized blower, will make 10 psi of boost at redline... and less below redline, its just how centri blowers work.

With a properly sized turbo that isnt way too big for a combo, if it is set to make the same 10psi at redline it will almost always make more boost than a centri down low. In fact most properly size turbos will make full boost as low as peak torque and hold it to redline.

Peak torque IS peak cylinder pressure. Turbos almost always make way more torque than blowers for a given amount of boost.

Look no further than WRX/STIs... the ONLY way they get those motors to live to make 400hp+ is to absolutely kill the peak torque (cylinder pressure). They have to be tuned so that they kill timing/and boost down low and let it come in with RPM. If they dont they blow up ringlands left and right.

When tuning, is it not the goal to achieve as much peak torque as possible?

If so, peak cylinder pressure should still be similar. The turbo does it with more boost and less timing. The centri does it with less boost and more timing.

Thus, the different timing events then occur at different cylinder volumes.

The limiting factor for both methods is knock.

As long as knock is avoided, cylinder pressure, be it N/A, turbo, blower, nitrous, is a non-issue.

Is it not possible for a blower car on race gas to have more cylinder pressure than a turbo car on pump 91/93?
 

slow306stang

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I'm 50/50 on the subject. Both turbo and blowers have their pro's and con's and its up to the owner of the vehicle to decide their goals. With modern blowers that are coming out its easy to make 1000whp+.

When my GT had the d1sc wastegated on 17-18psi it made 860whp 750wtq. My brothers hellion sleeper setup on 13psi made 880whp and 750wtq. It took 5 less psi to make more power than my car.

Now my car is making 1300whp with the f1a-94 but it took 30psi to get there. I'm sure a properly sized twin turbo setup could do 1300whp with about 24psi while needing less fuel to get there.

Now I will say my blower setup is simple. Its easy to work on, has no belt slip with the factory 8 rib, and boost level can be changed in 15 minutes.

Like I've said...I'm torn between the two. If I were to do it again I may go turbo.
 

97WHITEVENOM

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When tuning, is it not the goal to achieve as much peak torque as possible?

If so, peak cylinder pressure should still be similar. The turbo does it with more boost and less timing. The centri does it with less boost and more timing.

Thus, the different timing events then occur at different cylinder volumes.

The limiting factor for both methods is knock.

As long as knock is avoided, cylinder pressure, be it N/A, turbo, blower, nitrous, is a non-issue.

Is it not possible for a blower car on race gas to have more cylinder pressure than a turbo car on pump 91/93?
Of course you could kill the cylinder pressure of a turbo if you pull a bunch of timing at peak torque... that is exactly what I stated about sti motors to keep the pistons/ringlands alive.

No... horsepower is the goal, which means carrying torque as high up in the RPM band as possible.

A properly sized turbo will almost always make more boost down low compared to a centri. Turbos are easier on the motor because of less harmonics and strain on the crank. Also parasitic loss on the blower motor is higher than a turbo motor. There is some loss due to back pressure from a turbo, but nothing like the loss due to driving a blower. Because of that is you want to make equal crank HP from a blower you usually need to make more actual power from the motor.
But again. 10lbs of boost at peak, the turbo will almost always make more torque.

Also, you can destroy a motor without detonation, just from cylinder pressure alone for sure. Plenty of stock 5.0 blocks have cracked from cylinder pressure and/or rpm. Head gaskets blow from cylinder pressure too.

A blower car on race gas vs a turbo on pump????? What does that mean? If you have a 13.5:1 blower car on race gas, one would assume it would make more cylinder pressure than an equal motor running 8.5:1 compression. Static compression is very closely related to dynamic compression/cylinder pressure.
 

97WHITEVENOM

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I'm 50/50 on the subject. Both turbo and blowers have their pro's and con's and its up to the owner of the vehicle to decide their goals. With modern blowers that are coming out its easy to make 1000whp+.

When my GT had the d1sc wastegated on 17-18psi it made 860whp 750wtq. My brothers hellion sleeper setup on 13psi made 880whp and 750wtq. It took 5 less psi to make more power than my car.

Now my car is making 1300whp with the f1a-94 but it took 30psi to get there. I'm sure a properly sized twin turbo setup could do 1300whp with about 24psi while needing less fuel to get there.

Now I will say my blower setup is simple. Its easy to work on, has no belt slip with the factory 8 rib, and boost level can be changed in 15 minutes.

Like I've said...I'm torn between the two. If I were to do it again I may go turbo.
A d1sc at 18psi is starting to become pretty inefficient. If you would of spun your F1A94 slow enough to make 860hp it would have been alot closer to your brothers car boost wise I bet.

1300whp with a F1a-94! That blower is so sick.

I just finished building a dart block 400 sbc, ported AFRs, solid roller, with a d1sc blow thru e85. Should be on the dyno soon. I am going to spin the D1sc to max RPM. According to your old set up looks like over 900 hp might be possible on the engine dyno!
 

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