Article: adding a turbo to improve efficiency

[dremd]

An 04 Cobra buddy has a Nitros setup o his car, he uses a 1 gallon fuel cell filed with 107 low lead. works great for Boosting fuel octane during accel (extreme). I've tried to get him to run ethanol in it (107 octane I believe) but he never will. I don't see why the same couldn't be done with an efficient design.

[zjrog]

I knew I was forgetting something. Homogenizer. After seeing some really bad sneezes, I'm pretty sure I do NOT want fuel hitting the compressor blades...

I'm rather surprised I even remembered that much considering I haven't really given much thought to it in almost 30 years...

Originally Posted by trebuchet03

He didn't call it a turbo - he was adamant about calling it a homogenizer. Fuel was injected BEFORE the turbo I got to speak with someone that worked with him many many years ago. He said the car worked great, got extreme FE and good power but it had one critical problem - it wasn't reliable. He had said the engine was being rebuilt quite frequently.

[tjts1]

Originally Posted by diesel_john

one of the first turbo'd US production engines i remember was about a '62 buick starfire. it had water injection. are telling me that the first one was done right, and we have gone down hill ever since.

Early turbocharged engines used water to cool the intake charge because they didn't have intercoolers.

[dremd]

I've seen a dozen or so "draw through" carburator Setups, all drag strip "only" cars.
They all claimed no issues . . . . .
One advantage is that you do not need a BOV, main disadvantage I've heard concerns over is intake side turbo seals (suck the oil out) I have no Idea if they are founded or not.
I would "ass"ume that the turbo would vaporize fuel pretty darn well.

I have run water injection (10% fuel flow) pre turbo before with no ill effects (5k or so on the street) Vanes looked just the same.

[zjrog]

For a street/competition vehicle drawthrough is fine. Big issue with a draw through, if you develop a leak between the carb/throttle body and turbo, it COULD run away... This was a major reason Chrysler went to a blow through design after the first couple years of their turbo cars. And, it is easier to intercool before the carb/throttle body.

[DifferentPointofView]

I don't know about this. But has anyone thought of using a supercharger? From my "tuner car" knowledge, most turbo's make power at the higher end, while superchargers make power more at the lower end.

I could be wrong though, and I'm not much up on how superchargers have an effect on FE, so please correct me if I'm wrong.

[zjrog]

Superchargers are powered off the crankshaft, and make power pretty low, and lose efficiency as you go faster. They require a good amount of engine power just to turn (naturally, the more boost you want from one, the more power it takes to turn one...). As I recall, the production GM 3.8 liter V6 cars used some sort of bypass to avoid intake restrictions at higher speeds. But I could be wrong. Centrifugal superchargers are more efficient than the roots style, but again are limited by how fast they can be turned by the crankshaft... A turbo is powered off the exhaust, free power. Has very little parasitic drag on the engine.

There are turbo technologies to allow one turbo to make power throughout the powerband. These "Variable Nozzle Turbos" can easily be referred to as variable displacement too. Basically, the vanes in the compressor side can be adjusted to allow very little or a great deal of boost. If sized correctly, a VNT can act like a smaller turbo at lower engine RPMs and adjust the vanes to act like a larger turbo for more power or efficiency at higher RPMs.

Chrysler toyed with these in the late 80s early 90s, but they are found in very few cars. Chrysler turbo cars are lumped into 4 basic categories, Turbo I which is non-intercooled (early models were draw through, later were blow through, and even later still had increased displacement), Turbo II were always 2.2 liter and intercooled blow through. Not exactly rare, but hard to find (forged crankshaft and crossdrilled heads for better head cooling). Turbo III which was only offered in Dodge Spirit RT and Dodge Daytona RT was a 224 HP DOHC package that consisted of a 2.2 block with special heads. Last was the Turbo IV which was the rarest of all, 2.2 SOHC was essentially the same as any other 2.2 turubo motor, the magic was the VNT turbo and electronics.

Well, Probably rarest of all Chrysler turbos were the 6 3.0 liter V6 engineering mules that escaped from Chrysler. Originally intended for a special model of Daytona for 92 or so, the performance was such that Chrysler felt the Daytona would have drawn too many sales from the Dodge Stealth (same as a Mitsubishi 3000GT) and was nixed. How the motors escaped is anyone's guess. I do know where three of them are, two are in running cars (one is running around in Columbus, Ohio!)... I really only mention them in passing because they were the motors that got me thinking about turbocharging my own 3.0 liter V6 in my old minivan...

And I guess if I mention the Mitsubishi cars sold by Chrysler, I also need to mention the Starion with a tubocharged 2.6 and the Mitsu Eclipse/Plymouth Laser/Eagle talon triplets too. The triplets could be had with turbos and AWD... But I digress from the VNT discussion.

It is my understanding some diesel turbos are VNT. But not having paid a great deal of attention to diesels, I don't know which use them, or if any foreign manufacturer uses them. I can't imagine why not though.

[trebuchet03]

Originally Posted by DifferentPointofView

I don't know about this. But has anyone thought of using a supercharger? From my "tuner car" knowledge, most turbo's make power at the higher end, while superchargers make power more at the lower end.

I could be wrong though, and I'm not much up on how superchargers have an effect on FE, so please correct me if I'm wrong.

Reiterating zjrog's post...

SC do not recycle power - the use power putting a load on the engine.
Exhaust driven TC recycles waste heat into usable work.

Variable geometry turbines solve some of the issues with operating range. But if all you want is low end boost - use a small turbo

Then... There's the Comprex supercharger... Which uses exhaust pressure to directly compress intake air... And synchronized by a pulley. The pulley isn't used to compress air, so you don't have the power consumption of a supercharger. Calling it a supercharger is a bit of a misnomer, but eh...



The only production car to ever have one was a Mazda Capella (think 626) Diesel.

[roflwaffle]

Pressure-wave superchargers are dope, and rare as hen's teeth.

[tputus]

http://www.swissauto.com/uploadfiles/EN_20006B.pdf