Turbo or Supercharged


BelgianGT

GT Owner
Jul 10, 2010
382
Belgium
Hi guys

I've been playing with the idea of an additional FGT and would like some drivers experiences on turbo's. According what people tell me the supercharged ( as a whippled I already have) is more viscious than the Turbo package. Reason : the turbo needs to build power first before one car start enjoying the whereas the supercharged is immediately off.

What's your experiences?
 

Empty Pockets

ex-GT Owner
Mark IV Lifetime
Le Mans 2010 Supporter
Oct 18, 2006
1,361
Washington State
I assume you're talking roots-type s/c (such as the FGT's factory unit) vs. a turbo setup as opposed to an axial flow s/c vs turbo.

You've already explained the effective difference between the systems just fine, IMO. But I'll put on my flame retardant suit and attempt to elaborate a bit anyway.

Generally speaking, turbo systems build boost/power with rpm...whereas a roots s/c can provide its max boost/power at any rpm. The roots is a fixed displacement unit...each rotation compresses a fixed amount of air. A turbo's boost is directly related to rpm...the higher the rpm, the higher the boost. (Now, one can get into the whole area of small + large turbo combo setups that supposedly eliminate most if not all of the turbo "lag", blah, blah...but, I don't think that's what you're considering.)

So, realistically speaking, 'bottom line is if the vast majority of your real world driving is done on the street (at speeds under 100-120 mph!) - a s/c will provide a greater amount of <4500 rpm boost/power in any gear at any speed...and do so predictably. That is, there'd be no "lag" involved...'no sudden boost/power 'surprise' that may come when you're not really expecting/wanting it. (All the aforesaid assumes we're talking apples-to-apples boost level 'settings' for both systems.)

BUT, if you intend to run the Texas Mile, or whatever, the turbo route is the way to go...at least for now.


(BTW, I'm sure there have been several threads/comments posted here on The 'Forum regarding this topic if you'd care to use the site's search engine to locate/check them out. I'm just too darned lazy this morning or I'd have done that for you and posted a link or two!)
 
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Xcentric

GT Owner
Mark II Lifetime
Jul 9, 2012
5,213
Myakka City, Florida
I assume you're talking roots-type s/c (such as the FGT's factory unit) vs. a turbo setup as opposed to an axial flow s/c vs turbo.

GTs have Lysholm (twin screw) vs. Roots (lobed rotors) superchargers. The Whipple is also a Lysholm.
 
Aug 25, 2006
4,436
GTs have Lysholm (twin screw) vs. Roots (lobed rotors) superchargers. The Whipple is also a Lysholm.

True however the difference is the rotor design and case clearance hence the Lysholm is simply speaking a more efficient design rather than an alternate design.

IMO that which Empty Pockets shared is "spot on"

Takes care

Shadowman
 

nota4re

GT Owner
Mark IV Lifetime
Le Mans 2010 Supporter
Feb 15, 2006
4,176
Here we go again....

Put a Whipple on, select pulley (boost) size, select good tune, and what you see is what you get. Not so with TT installs. Many, many variables with different sized turbos, different plumbing to and from turbos, different wastegates, different boost controllers, etc. all of which can make a BIG difference in the way the car feels and drives. Take the difference between a V1 Heffner TT and a V2 Heffner TT - and the difference in driveability is simply amazing.

IMHO, if you took a 10 minute test drive in a well-tuned Whipple car and then jumped in a drove a V2 Heffner TT car, more than 90% of owners would want the TT. That's my honest opinion - as I have driven both and it is just a hands down different experience. But, that is NOT the end of the story. A Whipple install will cost you about $12,000 installed whereas the Heffner TT is about 3X that cost. Also, the Whipple allows you to use cats and is CARB approved whereas the TT's are typically cat-less (there are exceptions) and NOT CARB approved.

Both mods are amazing, IMO, and either one will put a very, very broad smile on your face!
 

Fubar

Totally ****** Up
Mark II Lifetime
Le Mans 2010 Supporter
Aug 2, 2006
3,979
Dallas, TX
Clearly both systems have their pros/cons. I'm not sure that one system is better than the other but a buyer needs to be informed.

If straight line power is your main goal then turbos will provide the greatest bang-for-the-buck. The turbo will never provide instant power, no matter what anybody says... all turbo system have some degree of lag. IMHO this lag is not acceptable but if you can tolerate the lag, then you will get more power, less heat and better fuel efficiency, with the added bonus of being able to turn up the boost for race fuels very easily (simply adjusting the blow off setting).

Superchargers can provide almost instant boost but the engine needs to be designed around the SC. Of course the stock GT motor was designed around a SC'r and Whipple has just expounded on this design but there is a limit. Heat is the biggest issue in my book, both to motor temp and intercooler ability. The more boot you add via a SC the shorter your run time will be... i.e.: more cool down. However odds are you will not be pressing the motor or the boost beyond it's ability to cool and thus the "duty cycle" will be in the clear, just keep in mind that 5-6 laps with a stock motor will turn into 2-3 laps with a 4.0L Whipple. Whereas the turbos can usually stay out of the red for at least 5-6 laps and maybe even more.

Do you have goals? Do you plan on tracking? Do you just want to beat the guy with the turbo Viper on the highway? Is it just a fun-factor you are looking for? These are things you really need to know before you jump into a big build.

Cheers
F
 
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BlackICE

GT Owner
Nov 2, 2005
1,416
SF Bay Area in California
Let's not forget the SC/TT options too. Mullet must be on vacation and the option of NOS on all systems. :lol
 

Empty Pockets

ex-GT Owner
Mark IV Lifetime
Le Mans 2010 Supporter
Oct 18, 2006
1,361
Washington State
Let's not forget the SC/TT options too. Mullet must be on vacation and the option of NOS on all systems. :lol


Trouble maker!
 

Mullet

FORD GT OWNER
Le Mans 2010 Supporter
Oct 21, 2008
2,468
Houston Texas
Let's not forget the SC/TT options too. Mullet must be on vacation and the option of NOS on all systems. :lol

I've been watching. :)

Just TT/SC it and forget about any lag. Best of both worlds. Add a little spray for those times when turning it to 11 is so right.
 

Fubar

Totally ****** Up
Mark II Lifetime
Le Mans 2010 Supporter
Aug 2, 2006
3,979
Dallas, TX
I agree, that the TT/SC seems like a great option. I suspect it still has a heat handicap but at least you get the top end power and low end torque. It also has a "badass factor" that makes it fun as hell at the car meets... where two or three extra power adders equals "King of Parking-Lot" trash talking merits. I'd definitely go this route if it is an option.

Mullet, do you think having the crank double-keyed is a 'must' for this option?
 

Mullet

FORD GT OWNER
Le Mans 2010 Supporter
Oct 21, 2008
2,468
Houston Texas
I agree, that the TT/SC seems like a great option. I suspect it still has a heat handicap but at least you get the top end power and low end torque. It also has a "badass factor" that makes it fun as hell at the car meets... where two or three extra power adders equals "King of Parking-Lot" trash talking merits. I'd definitely go this route if it is an option.

Mullet, do you think having the crank double-keyed is a 'must' for this option?

I know Hennessey has done 25-35 of them and I bet my failure was the only one like that or he would be requiring it.
 

Fubar

Totally ****** Up
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Aug 2, 2006
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I figure it was a fluke. Theoretically, the turbos should take the stress off of the crank.
 

BlackICE

GT Owner
Nov 2, 2005
1,416
SF Bay Area in California
I figure it was a fluke. Theoretically, the turbos should take the stress off of the crank.

At least on the snout for the equivalant HP and TQ.
 

Fast Freddy

GPS'D 225 MPH
Mark II Lifetime
Aug 5, 2005
2,684
Avondale, Arizona
a double keyed crank has to do with the supercharger and not the turbo's. a double keyed crank is a must for the 4.0L whipple....

from what i can tell the 3.4L whipple doesn't need it....
 
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Wwabbit

GT Owner
Mar 21, 2012
1,259
Knoxville, TN
Do you have goals? Do you plan on tracking? Do you just want to beat the guy with the turbo Viper on the highway? Is it just a fun-factor you are looking for? These are things you really need to know before you jump into a big build.
F


+1 , but if you don't have specific goals and budget isn't a factor, then Mullet has your answer
 

skyrex

FORD GT OWNER
Mark II Lifetime
Apr 11, 2008
2,115
Lake Las Vegas, Henderson, NV
My answer to this question may seem overly "direct" but that is how I am. I have driven every type of GT set-up except the TT/SC. When I got my second GT I could not wait to get the SC off and get it back to being a TT like my first car. A lot of people talk about turbo lag, but I just don't see it....and I drive my car all the time. At one time maybe that was a factor, but in a high horsepower application like this I have never felt it. The car responds at all times and I would consider myself, as a lot of us would :wink, an above average driver. Could a great driver get more out on the low end out of an SC or TT/SC than a TT. Maybe, but as far as I know no one has lined the up a Whipple, TT/SC and a TT side by side and let a expert third party drive the cars back to back to back. Until that happens this is really not an objective discussion.

This is a driver question. What is your goal?? If it is to take your friends on a thrill ride with a quick launch to 60mph or take them on the highway and downshift from 4th to 3rd and stab the pedal to hear them go crazy save your money and get a Whipple. Impressing those people will not be hard. Do you want to be able to "say" you have a 1,000hp car and take it to the dyno occasionally to show how powerful your car is?? (It still shocks me how many people have high HP cars and never drive them for effect) If the car is for track or high speed events that may change your answer as well. I don't speak tech, I just drive. I swallowed hard at the price of the TT......until I drove it. After that I never looked back. As a side note some of us have an in cabin boost controller which allows us to adjust the level of boost on the fly. That way you can have a "tame" 700+ rwhp, then adjust it up from there.

I have said it before and I will say it again. All of the set-ups are fantastic. When you were a kid if someone told you that you would someday own a car that would be making somewhere between 700-1200hp you would have thought they were nuts. The fact that we have cars that not only do that, but do it reliably with minimal problems is automotive heaven.
 

RALPHIE

GT Owner
Mar 1, 2007
7,278
I like Kendall's cost comparison between the two systems. Bang for the buck, which is how Corvettes are normally compared to European Supercars. But, then again, if cost is no object, the situation may reverse itself.

I would rather compare the two systems with the idea of equality. For the same result, and that result being equal Rear Wheel Horsepower and Torque (RWHP & RWTQ), how do they compare?, since each can achieve identical levels with enough money, hardware and engineering. I see it as follows:

The supercharger system is likely a less expensive and more performance oriented system up to about 1,000 wheel horsepower. However, let's not forget that to achieve this level, the prime mover (the engine) must create enough power to operate the supercharger, in addition to the power to the transmission input shaft. At a given point (which I have postulated to be at ~1,000 rwhp, a debatable number), the strength of the motor should be increased to withstand the total power that the prime mover must generate. In contrast, the turbocharger system does not place much more strain on the prime mover - just the additional restriction on the exhaust cycle to spin the snails. Once the momentum has gotten the unit spinning, the turbo can increase boost without significant additional strain on the bottom end. So, while the supercharger system may be less costly up to a given power level, above that level will require significant cost increase to the strength of the prime mover due to the demands of the supercharger, whereas to reach that same level with the turbo system will allow the power to be transmitted more efficiently.

Thus, each sytem has its advantages, depending upon the desired rear wheel output level of the system.
 
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RALPHIE

GT Owner
Mar 1, 2007
7,278
PS

As a postscript, let me add that for a given rear wheel power level, the turbo system puts much less strain on the components of the prime mover, thus significantly improving its endurability. I believe this is why the Auto Union turbo diesels have been so successful in endurance racing.
 

Fubar

Totally ****** Up
Mark II Lifetime
Le Mans 2010 Supporter
Aug 2, 2006
3,979
Dallas, TX
a double keyed crank has to do with the supercharger and not the turbo's. a double keyed crank is a must for the 4.0L whipple....

from what i can tell the 3.4L whipple doesn't need it....
Yes it does (to some degree). I was asking because Mullet is making a good deal more boost, the SC must spin faster (even when the turbos are pushing air trough it) which means it is likely geared lower… however the big additional strain of a SC comes when you let your foot off of the gas or use the motor to slow the car, then you are adding a massive load on the crank to slow the motor, instantly. With the turbos on the back of this configuration it should reduce the stress on the crank as the turbo’s spool up and it might even begin to push the crank (that is completely theoretical, I have no real world experience on this). I really thought Mullet crank would last longer than most people making being power but then it broke. I figured Hennessey looked closely at the cause of the brake. I was just wondering what he decided.

+1 , but if you don’t have specific goals and budget isn’t a factor, then Mullet has your answer
I don’t think it ridiculously more money for this setup. Hennessey using the stock blower so it basically a little more plumbing and boom… magically mechanical perfection (sorta).

My answer to this question may seem overly "direct" but that is how I am. I have driven every type of GT set-up except the TT/SC. When I got my second GT I could not wait to get the SC off and get it back to being a TT like my first car. A lot of people talk about turbo lag, but I just don't see it....and I drive my car all the time. At one time maybe that was a factor, but in a high horsepower application like this I have never felt it. The car responds at all times and I would consider myself, as a lot of us would :wink, an above average driver. Could a great driver get more out on the low end out of an SC or TT/SC than a TT. Maybe, but as far as I know no one has lined the up a Whipple, TT/SC and a TT side by side and let a expert third party drive the cars back to back to back. Until that happens this is really not an objective discussion.

This is a driver question. What is your goal?? If it is to take your friends on a thrill ride with a quick launch to 60mph or take them on the highway and downshift from 4th to 3rd and stab the pedal to hear them go crazy save your money and get a Whipple. Impressing those people will not be hard. Do you want to be able to "say" you have a 1,000hp car and take it to the dyno occasionally to show how powerful your car is?? (It still shocks me how many people have high HP cars and never drive them for effect) If the car is for track or high speed events that may change your answer as well. I don't speak tech, I just drive. I swallowed hard at the price of the TT......until I drove it. After that I never looked back. As a side note some of us have an in cabin boost controller which allows us to adjust the level of boost on the fly. That way you can have a "tame" 700+ rwhp, then adjust it up from there.

I have said it before and I will say it again. All of the set-ups are fantastic. When you were a kid if someone told you that you would someday own a car that would be making somewhere between 700-1200hp you would have thought they were nuts. The fact that we have cars that not only do that, but do it reliably with minimal problems is automotive heaven.
I disagree here, much like you, I have driven both and deeply considered the turbo route but the lag is there in every flavor of the turbo setup I have seen. There is no lack of power when you want to getty-up but there is always a “wall of power” that follows as the turbos spool up. I don’t think this is my opinion, as much as a solid pro/con of the turbo setup. If turbos could be managed perfectly, then everybody would use them.

I like Kendall's cost comparison between the two systems. Bang for the buck, which is how Corvettes are normally compared to European Supercars. But, then again, if cost is no object, the situation may reverse itself.

I would rather compare the two systems with the idea of equality. For the same result, and that result being equal Rear Wheel Horsepower and Torque (RWHP & RWTQ), how do they compare?, since each can achieve identical levels with enough money, hardware and engineering. I see it as follows:

The supercharger system is likely a less expensive and more performance oriented system up to about 1,000 wheel horsepower. However, let's not forget that to achieve this level, the prime mover (the engine) must create enough power to operate the supercharger, in addition to the power to the transmission input shaft. At a given point (which I have postulated to be at ~1,000 rwhp, a debatable number), the strength of the motor should be increased to withstand the total power that the prime mover must generate. In contrast, the turbocharger system does not place much more strain on the prime mover - just the additional restriction on the exhaust cycle to spin the snails. Once the momentum has gotten the unit spinning, the turbo can increase boost without significant additional strain on the bottom end. So, while the supercharger system may be less costly up to a given power level, above that level will require significant cost increase to the strength of the prime mover due to the demands of the supercharger, whereas to reach that same level with the turbo system will allow the power to be transmitted more efficiently.

Thus, each system has its advantages, depending upon the desired rear wheel output level of the system.
I really think a properly designed SC setup is more expensive than turbos but simply added a bigger SC to the Ford setup is relatively cheap. I think the limit of cheap rwhp with a SC is going to be around 800. Turbos will give you 950-1000 but after that you need to add a fuel system and more cooling and more tire and more heat shields and more $$$$$$$

Again, your goals are the most important thing you can decided before you make this decision.
 

Mullet

FORD GT OWNER
Le Mans 2010 Supporter
Oct 21, 2008
2,468
Houston Texas
Fubar, I think you are over anaylizing the SC/TT. For the record my stock SC is running the stock SC pulley.