Bank's Turbo

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Lextreme II

Active Member
Here is a beautiful work of art:
TTurbo-frontleftquarte-lg.jpg

TwinTurbo-offsideLeft-lg.jpg


Copy of bankpower.com

"By C.J. Baker

Have you ever ridden in a vehicle powered by a properly engineered twin-turbo V8? No, a single-turbo V8, or heaven forbid, a single-turbo four cylinder is not the same thing, not even close.

We’ve all heard the wisdom that there’s no substitute for cubic inches, but cubic inches of what? Is it cubic inches of engine that count, or cubic inches of air in the combustion chamber? It’s obviously the latter. So consider this, 15 psi of boost effectively doubles the size of an engine. That means 15 psi of boost will make a 350-cubic-inch performance engine seem like a 700-cubic-inch performance engine!

Actually, this picture isn’t accurate. If you understand engines, you’ll immediately realize that 15-psi boost more than doubles the performance an engine. It does this for two reasons: first, the internal friction of the engine remains largely the same regardless of boost, so the extra power from turbocharging is almost totally available to power the vehicle; and second, the 15 psi of boost in the induction system actually helps push the pistons down on the intake stroke whereas the intake stroke created a pumping loss (negative torque) when the engine was normally aspirated.

Now you may be thinking that the turbochargers create exhaust backpressure that increases the pumping loss on the exhaust stroke, but let’s go back to the first sentence of this discussion — we’re talking about a “properly engineered” system. That means the exhaust restriction created by the dual turbos will be minor, and that boost pressure will always exceed exhaust system backpressure. Simply translated, in terms of performance, a good twin-turbo 350 V8 will turn your inside out!

Okay, just for fun, let’s compare our 350 twin-turbo V8 at 15-psi boost to a 120-cubic-inch compact four cylinder running 30 psi of boost — twice that of the V8. By our rule of thumb, the little four-banger will now be flowing air equivalent to a 360-cubic-inch normally aspirated engine. That’s impressive for a small engine, but it will still have only half the power potential of our twin-turbo V8 running at half the boost. If you push the V8 to 30-psi boost, you’ll have the equivalent of 1050 cubic inches and over 1500 hp, if it is done correctly.

By now you get the point. Bigger engines add power, but turbocharging bigger engines really gets the job done. Happily, there’s more good news associated with turbocharging the small-block Chevy V8, and almost all of it comes down to durability. To begin, the performance industry offers a variety of high-strength cylinder blocks in both iron and aluminum. Thicker main webs and four-bolt main caps are just what a turbocharged engine needs. Next, the small-block Chevy uses five head bolts or studs surrounding each cylinder to help secure head gaskets. And of course, the aftermarket has a variety of premium head gaskets too. Then there are other heavy-duty parts readily available, such as forged crankshafts, forged connecting rods, forged pistons, special piston pins, and premium rings and bearings.

Finding all of these things is difficult for other engines, especially for four-cylinder engines.

Of course, the small-block Chevy V8 also benefits from a wide variety of high-performance cylinder heads, intake manifolds, and valvetrain pieces. Simply stated, nearly everything that improves airflow on a normally aspirated engine will also improve total flow on a turbocharged engine.

The next good news is that extreme duty drivetrain parts are readily available for rear-wheel-drive vehicles with V8 engines. This includes clutches, transmissions, u-joints, differentials and axles. Most of this was developed for drag racing or circle track racing. Such strength and durability is important when dealing with real power. For example, a 350-cubic-inch V8 running at 20-psi boost is capable of roughly 900 lb-ft of torque! You don’t feed that through a front-wheel drive transaxle to high-traction tires — at least not more than once.

Turbocharging is fun. It’s addictive. How much power can you make?

There are always big-block engines to consider, and in fact, Banks is developing a drag car with a 526-cubic-inch engine with four turbochargers. Admittedly, such an engine stretches the bounds of credibility. It would seem like that is the ultimate, but there’s another entire chapter to turbocharging that’s just being opened. Can you say diesels at 150-psi boost? Don’t blink. They’re not coming … they’re already here! "
 
Very interesting reading, and some very nice pics!

The writer says that a single turbo v8 can't be compared to a twin turbo v8. Any comments to this?
 
200sx-v8 said:
Very interesting reading, and some very nice pics!

The writer says that a single turbo v8 can't be compared to a twin turbo v8. Any comments to this?
Just some marketing bullshit. In America we do that a lot.

Andrew
 
nice.. but dont forget the heat that compressing air creates, lowering the efficiency of the engine...it is very perty, though.
 

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I saw that a long time ago on some website, but it's so pretty! I wouldn't worry about heat. Most v8 / big block drag racers & big diesel racers don't intercool for whatever reason. Be it a slight loss of responce, or they can't afford the PSI drop, or they simply don't find the need.
Since it's form Banks, it wouldn't surprise me if the box ontop of the carb is an integrated water/air intercooler.

If I had a racecar, I'd pimp a roots blower off ebay. Make a few psi for the sake of low end torque, then two small intercooled turbos hanging off the manifolds blowing through the S/C. Talk about a massive amount of low end responce that runs almost completely through the top end.
That & it's just fun what you can do without expencive stuff LoL!
 
andrewb70 said:
Just some marketing bullshit. In America we do that a lot.

Andrew
Marketing bullshit?? :feedback: maby you can validate that statement with som info?

Single V.S Twin turbo (both in optimum setup):

An optimum single setup can pump more peak hp because larger turbos can be built more efficient than small.

An optimum twin setup will spool faster and create a better powerband

Exhaust piping on a twin can be made more efficient
Single turbo tubing can be wery bulky on both exhaust and air side.
Single turbo air side piping can often be built more efficient
Twin turbo setups is wery often more expensive (twin turbos, twin wg, piping etc.)

What you will use your car for and how its geared etc.. is what makes one setup better than another, not the turbosetup itself.
 
Simple fact? No... Not at all.
IMHO it's nothing more than a largely misunderstood case of diminishing returns!!!
It all goes back to exhaust power VS spinning a turbine. As you add turbos you not only divide exhaust energy used to spin each turbine, but you increase the time between exhaust pulses. Even worse is that despite that, you *still* have to make the same amount of power in the end.
It simply doesn't work all of the time! Once you get away with running those tiny ass to small sized turbos the difference between spool times is nearly negligible.

Think I'm talking total bullshit? Research it first! The best examples would be the few 3 turbo 2jz-gte, or 4 turbo v8 dynos of "street engines" that float around. The powerbands are anemic. Since the problems I put against multiple turbo setups are compounded exponentially - It's very obvious to see on those setups.
 


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