Twin-Turbo Or Supercharger?

[jonboyNY]

interesting question for Butch & gandolphxx and for any other gurus:

A guy asked me what if you put a twin turbo setup in an AV then a supercharger. He said turbos are more efficient then a supercharger and give alot more power.

He said you would have to go with a custom fab setup.

looking at 15PSI or more.

What you guys think?

 

[steelheadchaser]

Turbos typically aren't used by themselves on heavy weight vehicle applications, the exception being diesels. Turbos suffer from lag, while the fan is spooling up (it is driven by exhaust gas). They work well in higher rpm applications.

 

[KenHicks]

And 15psi boost is a lot isn't it? More than I'd want to feed a stock engine. 15psi is a lot for a turbo charger too isn't it? unless at extreme rpm

Just my buck two ninety eight

 

[gandolphxx]

Turbo's like centrifugal superchargers tend to assist at the higher RPM's, your truck needs the help at the lower RPM's IMHO.

Also, I wouldn't want to be in the truck when you put 15 psi to the heads.

 

[jonboyNY]

well I personally would not put more then 10-11psi.

2nd, you can tune the turbo for low rpm output.

3rd you can adjust the psi from inside the car, supercharger you cant.

4th the turbo is less stress on the engine then a supercharger is.

but im interested to know has anyone known of anyone who has tried turbos on a truck, i know of a few who had unreal performance 11-12 sec quarter miles with fords i dont know for any chevys.

personally i have a twin turbo porsche, i like turbos, they are quiet, all race car engines in the indys and any major automaker who has a race car usually employ turbos, they have been around and have never failed.

most people say superchargers are better for takeoff.

however, i have seen cars not trucks who have turbos destroy 0-60 times on other competitors.

 

[steelheadchaser]

One of the reasons turbos kick out more power per pound of boost is that there are no parasitic losses due to driving impellers off of the crank shaft. As far as "tuning" a turbo for low rpm, are you referring to the use of a waste gate?

As far as race cars using them, that is correct. Race cars, and you Porsche are usually made to be as light as possible and practicable. They work very well as long as rpms are kept up.

Your statement that "they have been around and have never failed" is flawed. They make a helluva mess when they "go away".

"Most people say superchargers are better for takeoff" Really? This is the first time I have ever heard that. I don't see a lot of them used on 1/4 milers. JMHO, YMMV

 

[jonboyNY]

yes i am...external wastegates.

 

[jonboyNY]

also i know of one late model chevy truck that has:
a stroked big block to the tune of 534ci, studded, grouted and o-ringed, TT 742hp/781tq on the motor, plus a 600hp fogger from Nitrous Express for a total 1350hp on pump gas, 20" Budnik billet wheels, custom airbag suspension (rear has 20" of travel and a 6-link) and it still has power windows, power doors, power steering, power brakes, tilt, cruise and air conditioning!

 

[steelheadchaser]

also i know of one late model chevy truck that has:
a stroked big block to the tune of 534ci, studded, grouted and o-ringed, TT 742hp/781tq on the motor, plus a 600hp fogger from Nitrous Express for a total 1350hp on pump gas, 20" Budnik billet wheels, custom airbag suspension (rear has 20" of travel and a 6-link) and it still has power windows, power doors, power steering, power brakes, tilt, cruise and air conditioning!

I once met an SR-71 Blackbird pilot. His "sled" ran two J58 engines @32,500 lbs (Total 65,000 lbs of thrust) and is capable of 2,193 mph. It didn't have a tilt wheel though.

 

[sparky]

Turbo's like centrifugal superchargers tend to assist at the higher RPM's, your truck needs the help at the lower RPM's IMHO.

Also, I wouldn't want to be in the truck when you put 15 psi to the heads.

lol

 

[DS]

I hate to say it, but whoever told you that a factory Chevy 5.3L engine would handle 15 psi was full of it. And why twin turbos? You said you have a Porsche twin turbo, so I would assume you understand the difference and reasoning behind twin turbo rather than single turbo setups? Twin turbos are usually used sequentially, like the famed last generation Toyota Supra. One turbo kicks in initially for low end, the other takes over for high end, eliminating a lot of the lag associated with a single large turbo. Are the fasted modified Supras twin turbos? No, they rely on a single large turbo, like a to-4.

also i know of one late model chevy truck that has:
a stroked big block to the tune of 534ci, studded, grouted and o-ringed, TT 742hp/781tq on the motor, plus a 600hp fogger from Nitrous Express for a total 1350hp on pump gas, 20" Budnik billet wheels, custom airbag suspension (rear has 20" of travel and a 6-link) and it still has power windows, power doors, power steering, power brakes, tilt, cruise and air conditioning!

As far as this goes, my question is....Why in the hell would anyone do that?? I considered supercharging my Av and modifying the suspension heavily. I then considered the fact that I would be investing this much cash into a truck that will endure about 40000mi per year of commuting and travels, weighs 6500lbs, and has the aerodynamics and handling characteristics of a battlecruiser. No offense to anyone who has done these things intended, as I would jump on it if I thought it was worthwhile, everyones needs and desires are different. I decided to just heavily modify the thing for audio, which makes sense for me since I spend a lot of time on the road.

 

[jonboyNY]

One of the reasons turbos kick out more power per pound of boost is that there are no parasitic losses due to driving impellers off of the crank shaft. As far as "tuning" a turbo for low rpm, are you referring to the use of a waste gate?

As far as race cars using them, that is correct. Race cars, and you Porsche are usually made to be as light as possible and practicable. They work very well as long as rpms are kept up.

Your statement that "they have been around and have never failed" is flawed. They make a helluva mess when they "go away".

"Most people say superchargers are better for takeoff" Really? This is the first time I have ever heard that. I don't see a lot of them used on 1/4 milers. JMHO, YMMV

go to superchargersonline.com they pretty much plaster that superchargers are better for take off, and i dont mean 1/4 mile...i mean 0-60 personally.

2nd, turbos almost always outlast any supercharger, at least thats what i feel and about 18 other people i know. turbos are efficient, there are disadvantages to them but the supercharger has more.

why does porsche, mercedes, bmw, toyota, volvo to name several incorporate turbos vs superchargers? there must be a reason. because they last.

just recently mercedes decided to incorporate a supercharged version of their cl55. because they wanted to make it affordable.

 

[jonboyNY]

I hate to say it, but whoever told you that a factory Chevy 5.3L engine would handle 15 psi was full of it. And why twin turbos? You said you have a Porsche twin turbo, so I would assume you understand the difference and reasoning behind twin turbo rather than single turbo setups? Twin turbos are usually used sequentially, like the famed last generation Toyota Supra. One turbo kicks in initially for low end, the other takes over for high end, eliminating a lot of the lag associated with a single large turbo. Are the fasted modified Supras twin turbos? No, they rely on a single large turbo, like a to-4.


As far as this goes, my question is....Why in the hell would anyone do that?? I considered supercharging my Av and modifying the suspension heavily. I then considered the fact that I would be investing this much cash into a truck that will endure about 40000mi per year of commuting and travels, weighs 6500lbs, and has the aerodynamics and handling characteristics of a battlecruiser. No offense to anyone who has done these things intended, as I would jump on it if I thought it was worthwhile, everyones needs and desires are different. I decided to just heavily modify the thing for audio, which makes sense for me since I spend a lot of time on the road.

you answered your question DS, the 1st turbo is for low end the 2nd is for high end. thats the reasoning

 

[Butch]

The problem with the Turbos is that they make there Power at High Boost levels jon.., usually at 10 lbs and above.., something the stock Heads, and gaskets could not handle..., not to mention the Pistons, and Bottom End...... To really get the advantage of the Turbos you would have to run Boost of 15 lbs, and above.., the first thing that would happen is you would start lifting the Heads, and blowing Head gaskets.., next would be the problem of pounding out, and cracking the tops of the stock pistons, and Ring lands.... The compression ratio on the stock 5.3 is far to high to run Boost above 10 p.s.i Max..., so you would really have to build an engine from scratch to handle Boost levels that high.. You could put in Forged pistons, good Rods, and Crank..., but the Heads could still never handle that kind of Boost.... At the 10/11 lbs Im running now..., Im really pushing it.., and wouldn't even consider trying to run anymore Boost.., and even as much as Ive beefed up My Drive Train.., Trans, Drive Shaft, Rear End.., its still on the ragged edge to hold up to the Power Im making now.., so you would have to install a complete new Drive Train to handle the Power..., and Twin Turbo's have a smaller power band than a supercharger..., so you would need a high stall converter, and a lot of gear to take advantage of the power that they make...., it would be a Very Expensive project..., and take a lot of Tuning to make it work right..., and in the End.., probably not worth it...... JMO

 

[DS]

you answered your question DS, the 1st turbo is for low end the 2nd is for high end. thats the reasoning

I wasn't asking myself, I was telling you assuming you didn't realize that.

why does porsche, mercedes, bmw, toyota, volvo to name several incorporate turbos vs superchargers? there must be a reason. because they last.

just recently mercedes decided to incorporate a supercharged version of their cl55. because they wanted to make it affordable.

Turbos make sense on a lightweight car. Why waste ungodly amounts of cash turboing the puny 5.3L when, if you were honestly planning on building a "worlds fastest AV" project, you would start with an engine swap? As for turbos lasting, who told you that they were eternal, or would outlast a supercharger? A bolt on supercharger kit would, in my opinion, but the most logical choice for someone wanting to increase the performance of their Av. If you wanted a truly fast truck, you would go and buy the upcoming Dodge with the Viper V10 and 6 speed manual and take it over to Hennessey for modification to even further improve it.

To answer the "Why does Porsche, BMW,.......incorporate turbos vs superchargers" question: Look at Toyota's Supra, which had a twin turbo version and a normally aspirated model, based on the same engine, a 3.0L I6 DOHC 24V. The power and torque difference was 220/210 vs 320/315. Why did Toyota make a turbo version? Because, can you imagine how much it would have cost to make an all-motor version of that engine crank out 320/315? Turbos equal cheap power (cheap vs the cost of all-motor engineering and materials) on a capable engine, and as someone above mentioned, they are not parasitic. It's not because they outlast superchargers, it's because they are more logical for that vehicle type.

Here's a novel idea for you if you really are planning on doing this: Do a turbo, supercharged 5.3L. There is a turbo, supercharged deisel New Beetle in existance that is incredibly fast. A Kaira low-profile truck unit and a bored block equal 295hp at the front wheels.