Why are the GS owners with RMM Supercharger are Changing to Turbo

[morris]

nkdsgvjkl;;dsagjo;dsalgfmjol;dsa

 

[stevechumo]

The tranny rebuild was 3k.

I already had a dragon torque converter with stator pump so that was a separate issue all together...

$3K for the strenthened tranny isn't bad. I thought it would cost more than that. It's a good choice not to have it swapped to a manual tranny. A manual tranny swap might cost just as same.

 

[jibbby]

I thought I would drag up this old thread to help shed some light on why people are choosing turbo's over supercharging...

 

[V8Datto]

What turbo did he use?

 

[stevechumo]

I thought I would drag up this old thread to help shed some light on why people are choosing turbo's over supercharging...

Not only talking about maximum power, the main reason that people choose turbo over supercharger is because the engine runs more efficient with turbo, although customizing a turbo system requires a lot more work. Supercharger wastes the engine hp to turn it while the turbo only deals with the backpressure. In theory, a supercharger wastes 20% of crank power. I'm not so sure about it, but it's a theory by those engineers. However, with proper sizing, the turbo will deal with the backpressure as a minor issue. Also, some superchargers make irritating whining noise.

 

[morris]

What turbo did he use?

turbonetcis T62-1

 

[morris]

Not only talking about maximum power, the main reason that people choose turbo over supercharger is because the engine runs more efficient with turbo, although customizing a turbo system requires a lot more work. Supercharger wastes the engine hp to turn it while the turbo only deals with the backpressure. In theory, a supercharger wastes 20% of crank power. I'm not so sure about it, but it's a theory by those engineers. However, with proper sizing, the turbo will deal with the backpressure as a minor issue. Also, some superchargers make irritating whining noise.

I dissagree, the guys I know that ditched the RMM SC for a turbo setup did it because the RMM system could not give them the power they wanted. It wont work over 11 psi or so

 

[Lextreme II]

Morris,

Can you give use your complete update on your GS400? Boost is the hardest thing in supercharging.

 

[stevechumo]

I dissagree, the guys I know that ditched the RMM SC for a turbo setup did it because the RMM system could not give them the power they wanted. It wont work over 11 psi or so

You misunderstood me. What I meant was that "Not only the turbo can go to maximum hp, it also can run more efficient than the supercharger".

 

[morris]

No I followed you, but from the people I talk to no one really cares one way or the other about the engineering aspects of the system. The issue of efficiency never comes up on the street. It seems to be an aspect of the debate that is only relevant on the Internet. Guys want fast cars, they dont generally care about efficent engines.

 

[morris]

Here is the current setup

1. Engine
A. Rebuilt motor.
a. Forged Ross Low compression Pistons, 8.5:1 with .020 overbore
b. 440 CC injectors
c. Walbro 255 Fuel Pump
d. FAL Low profile fans (1.5” thick)
e. Greddy Catch can
f. Fluidyne Radiator
g. Powder coated valve covers, timing covers and intake manifold.
B. Turbo setup
a. Turbonetics T04E/T62-1
b. Vortech BOV
c. Turbonetics Turbo Evolution waste gate 6psi spring
d. Apexi SAFC2
e. Greddy PROFEC B-SPEC 2 Boost controller
f. Spearco FMIC
C. Transmission
a. Trans World race built transmission (good for up to 800rwhp)
b. Hayden Transmission cooler
c. 2650 RPM Precision industries Dragon Torque converter with stator pump
d. TRD LSD Stock 3.23 gears
2. Exhaust
a. Tanabe Super Medallion Cat Back
b. 3” Custom exhaust splits off into two 2.25” pipes
c. No CATS, No Resonators
3. Suspension
a. Tein Flex
b. Tein EDFC
c. TRD Blue Sway Bars
4. Exterior
a. Greddy Lip
b. Halo’s
5. Interior
a. Valentine1
b. Blinder M20 LASER Jammer
c. AEM UEGO Wideband
d. APEXI Boost Gauge

 

[jibbby]

Steve is correct...You do get considerable drain from the engines crank to power up a root supercharger...Limited space to house a huge supercharger is not possible in these Lexus's too..A smaller fitting supercharger has it's hp limits and that is the main reason people are dumping them....Turbo's that are run off the exhaust are simply much smaller in size for fitment...You can simply produce much more effecient power with the turbo's over the superchargeres when talking about mounting them into our Lexus's...

I think under the hood space is the main issue here...I personally have always liked the superchargers over the turbo's because of the even power distributed throughout the power band....No waiting for the boost to come on, no drastic power surges...The crank turns and so does the charger. However, the charger also has to be big enough for my liking...:Eyecrazy:

 

[morris]

I have been told that the Vortech SC that is included in the RMM kit is good for 700hp or more unfortuantely the design of the kit doesnt allow you turn up the boost high enough to make that kind of hp

Also as an FYI after being Supercharged and turboed, I to prefer the Supercharger.

 

[Lextreme II]

Morris,

Its not the supercharger unable to produce 700 bhp. Its the crank pulley is too small to supercharger. If you have a 7" to 8" pulley, the making 700 wouldn't be a problem.

 

[stevechumo]

No I followed you, but from the people I talk to no one really cares one way or the other about the engineering aspects of the system. The issue of efficiency never comes up on the street. It seems to be an aspect of the debate that is only relevant on the Internet. Guys want fast cars, they dont generally care about efficent engines.

That's true when many people on the streets don't care about the effiency issue of the engine. All they need is a fast powerful car. However, when the people who design and implement that system onto the car, they all do care. And they take all the cautions to make the car run at its best and tweak out every possibility to make it faster. Otherwise, the output power won't be maximized, given the same amount of $$ or other limitations. Power output is lagged, not linear to the RPM, gas that is burnt more than needed, engine temperature is risen up...etc. are all the efficiency issues of the supercharger & turbocharger systems. It's not just about the Internet debates.