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Discussion Starter #1
going for 700ish to the wheels as my desired power level, with a built 346 motor.

my question is this is there any benefit to using turbos over a blower? I know if will cost more money and if my only benefit is the adjustability of boost and ability to make big power then i guess i dont need turbos. I want 650-750 rwhp on pump gas and no real reliability issues. opininons? Turbo guys why did you opt twin snails over a blower? thanks boys this is all getting done with in the next 6 weeks i'll keep you updated :usa:
 

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IMHO, I think the Blower is the easiest, and most cost effective method. However, I am going TT just because I always wanted to do it.
 

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There's no such thing as "no real reliability issues" at that level. Having said that, I think that the turbo comes closer to that goal than the blower. The main issue with the blower will be the belt drive. Andy's got a great bracket, but IMO, the 8-rib belt is the limitation of all centrifical C5 blower setups. With the turbo, you just have to worry about the heat killing everything over time... Cost can be a factor with the turbo, as well.
 

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Superchargers are parasitical in nature; they rob hp to make hp. Turbos are more efficient. Look at the Viper community - all big hp cars are twin turbo for a reason and more and more people are moving away from blowers to turbos. You are getting into a hp range where you MAY experience belt slippage issues with a supercharger (depends who builds the car).
 

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Paul said:
Superchargers are parasitical in nature; they rob hp to make hp. Turbos are more efficient. Look at the Viper community - all big hp cars are twin turbo for a reason and more and more people are moving away from blowers to turbos. You are getting into a hp range where you MAY experience belt slippage issues with a supercharger (depends who builds the car).
I wouldn't disagree with Paul's statement.

Mike
 

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750rwhp from a centrifugal blower will not = 750rwhp from a properly setup turbo/twin-turbo setup. Yes, the PEAK #s will be the same, but the average power across the entire rev-range will be in favor of the turbo setup. Why? Well, even if the compressors are equally efficient, since boost/airflow from the centrifugal is directly proportional and related to engine rpm, you have limits as to how fast it can spin in the low, mid-range. The turbo will make peak boost much quicker, giving it a higher HP/TQ curve across the entire rev-range.

That being said, I can't imagine you'd be disappointed with either! :)
 

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Discussion Starter #7
I hear what you guys are saying. Cost isn't really an object, but I want to be getting more if I am spending more $ (if that makes sense). I am not out to be the fastest will I have belt issues on a SC'er at 650 rwhp? I dont think I will be displeased with that either. Does anyone have a 650 hp TT dyno graph vs a 650 hp SCer dyno?
 

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I think you could nail 650rwhp with a bigger than stock-motor and a supercharger, without breaking a sweat. Im sure a stock CID motor could do it too, but you might have to run a little more boost to do it, and you wouldnt have the low end advantage that extra cubes would offer.
 

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robiferretti said:
but I want to be getting more if I am spending more $ (if that makes sense)
I think that's what WA 2 FST was getting at; you'll pay more but you'll get more (better curve) from a turbo setup.

I'm sure there are plenty of LPE guys here that have a dyno sheet from a 650ish hp car.

Here's a dyno sheet from a 638 rwhp C5 that Cartek built:
C5 638rwhp/506rwtq dyno sheet
 

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I'm sure someone does. ;)

JWz06.
 

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The main issue with the blower will be the belt drive. Andy's got a great bracket, but IMO, the 8-rib belt is the limitation of all centrifical C5 blower setups. With the turbo, you just have to worry about the heat killing everything over time... Cost can be a factor with the turbo, as well.[/QUOTE]

Heat over time kills a turbo OR supercharged motor slowly.
Regarding the heat issue on turbos, the only time there is concentrated heat in the turbo is when the motor is in a boost mode rather than vaccum mode. and even then at 2 to 4 psi not that much heat either. Now, 8 psi or above there is a large concentration of heat but not for a very long time and not ALL the time. I am not dismissing the heat issue totally but under normal daily driving heat is not a factor. The turbo is the component that is subjected to the greatest concentration of heat and it cools itself through ambient air, oil and water through the bearings. Air into the motor is intercooled which helps its survival. The motor generates more heat under boost also as it is doing more work with increased cylinder pressures etc. Blowers do the same when under boost. Granted, either FI motor (TT or SC) will need a rebuild earlier than a NA motor due to the stresses and heat over a long duration. My 2cents.
 

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Sack Rat is on the money. My only slight correction would be that a _high-revving_ N/A motor will need a rebuild _at least_ as quickly as a FI setup, if not more often.

What would then be up for debate then becomes, "what is the definition of high-revving?" IMHO, for a motor like these, 7500rpm.
 

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The S/C route will definitely be less expensive. The advantage turbos have is that they reach full boost much sooner in the RPM band as well they are not prone to belt slip.

Mark
 

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Just want to add my 02

700hp at the crank NA or Turbo virtually generate the same heat. Just take a look at the definition of power. A SC motor will generate more heat as it has a significant parasitic drag to spin the blower.

And, for whats it worth, this is a sheet from my Stage X TTi kit on pump gas and 347cui. There is a guy in FL with an X at 8-9psi making 640/600 rear wheel still tuning and working the bugs out.

Phil


 

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Good to hear some .02 from some of the big boys. A little common sense from the voice of experience. :jammin:
 

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robiferretti said:
I hear what you guys are saying. Cost isn't really an object, but I want to be getting more if I am spending more $ (if that makes sense). I am not out to be the fastest will I have belt issues on a SC'er at 650 rwhp? I dont think I will be displeased with that either. Does anyone have a 650 hp TT dyno graph vs a 650 hp SCer dyno?
Rob, I really like S/C's but I'm realistic as well. The S/C will definately get you where you want to go hp wise but if money is no issue, I think reliability would favor the TT. I have the newest blower bracket ATI has produced and we still have some issues at the top end. If you really want to hit the big rwhp numbers with an S/C (850 to 1000), you're almost going to have to have a cog drive.

You asked for a dyno sheet and although this is not my most recent, it should serve your purposes...

Mike

 

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LPE Stage II TT Dyno

It took me a while to be able to post...technical difficulties .



Again that is a 346 on pump gas, low timing, and conservative A/F with about 12 lbs of boost. Compared to centrifuge-blowers the HP/TQ curves jump up alot faster and are less prone to "peaky" results. Area under the curve.

If your "true" goal is for 650-700 RWHP on pump gas with everyday reliability I would do a 427TT. It can be done with a 346 but you're going to lose the last part of your goal...everyday reliability.

JWz06.
 

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JWz06 said:
If your "true" goal is for 650-700 RWHP on pump gas with everyday reliability I would do a 427TT. It can be done with a 346 but you're going to lose the last part of your goal...everyday reliability.
JWz06.
IF the motor is setup right 700/700 is very reliable and not that far fetched. But, the main reliability issue with any power above 600/600 is detroying driveline parts..not the motor :(

This is an example, The rearend (#3 for the season ) had the best of everything installed, and a strut brace on top, which prolly saved the tranny.

 
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