LocostUSA.com

Don't get me wrong, high power is definitely possible if you go about it the right way, but it is neither cheap or simple.
Here is an engine I helped a guy in Scotland build, it is a Mitsubishi EVO engine in a hillclimb car.
It has both a supercharger AND a turbocharger.



He built it after reading a thread on the engineers Forum where I explained a lot of the details of how to go about building this type of "twincharged" engine.
This car regularly sets class records everywhere it has raced this season, it is a real winner.
It certainly makes a lot of power for a small engine, and not that high a boost either.
But it is not a 100 Hp stocker with bolt on bits, but a properly prepared EVO race engine, which started out with roughly around 400 Hp from the factory, and he developed it from there.
I have never met the guy, or seen the car, he is on the other side of the world. But we keep in fairly regular contact. He is absolutely thrilled with this motor !!

It is an old Vane VP930 eddy current roller dyno that I bought very cheaply.
It was an in ground dyno that survived a fire. Everything was burnt, except the underground part which was in excellent condition.
I built all my own electronics for the load control and monitoring system, wrote all the software, but have not used the dyno for a very long time.
At the moment the eddy current retarder part of it is removed and is in my electronics lab.
I must put the whole thing back together, but it is low priority, and other projects seem to keep getting in the way.

Well good for him. We are not talking about a built evo engine though (and if we were,thats not that impressive). I think the farther south past the equator the slower the cars get The only thing you really give up is reliability but boosting the crap out of a stock engine. In alot of cases you can make up the reliability with expendability The tune is still the key to how long it lasts.

No we are not talking about a built EVO engine, which is why I doubt your results with what you started from.

Reliability is all in the initial engineering design, particularly combustion and thermal management.

Final tuning is definitely very important, but carefully tuning an over boosted non intercooled heap of garbage with too much compression will never make it reliable.
It has to be designed properly right from the start.

Im sorry you havent figured it out and wont be able to help with this thread.

So who wants to talk about how to actually go about turbocharging their cars?

Old racers adage.

Fast cheap or reliable

PICK TWO

You forgot expendable LOL. If you have a $105 junk yard engine then you can afford to push it and not care if something bad happens.

He did not forget expendable. Expendable is the opposite of reliable. If you choose 'fast' and 'cheap', you don't get 'reliable', i.e. you need expendable.

An interesting discussion, but I can't get past the fact that some of the numbers given by warpspeed seem irrefutable. As I am not in the field, i'd like to understand more, so please explain how you can increase the power by 3.5 times without increasing the airflow by the same amount? It doesn't make sense to me yet.

Thanks

Slappy, you're consistently putting forth an undertone that's on the edge of being smart-ass with a touch of arrogance. If you back it down just a notch, everyone will become a lot more friendly. This isn't a forum of boyz in the hood that practice slapdowns and dissing others, it's really not necessary.

but of course. .. a known volume at an indicated pressure will have a calculatable mass. (temp adjustment goes in the calc's too, I didn't forget )

Combined gas law isn't it? You'd think I'd remember, I just took a refresher test last week for some of the gases I get to handle. Durn revenuers.

I realize we have a technological impasse here and it's certainly beyond me to solve it. However, there is obviously a lot of talent here and it would be very beneficial to look at some of the issues with reference to Locost turbocharging. For example, if the Corky Bell book isn't up to date, is there another one that is?

Other issues we might get into are power bands and how they are altered, realistic goals for street engines (especially the older ones like OHV and SOHC engines and the older Japanese stuff), engine control systems and fabricating.

It would be nice to see at least some schematic examples of the simplest turbo systems a person might build. Which components and modifications are absolutely required for solid, reliable operation and which things fit the "nice to have, but not necessary" category.

Lessons learned from any Locost builders with turbos installed could be very valuable. There is always a debate in these forums about how much horsepower is actually usable, but I haven't seen any driveability experiences related by turbo-Locost folk ( I have yet to read Rads build log) on the site. That would be good to hear.

Cheers,

One point often overlooked with turbocharging is the power to weight ratio of the original unturbocharged vehicle. A low power to weight and heavy vehicle will gain mightily from turbocharging.
They are brilliant on underpowered factory road cars.

An already very powerful and very light weight vehicle (such as a sports bike) will gain almost nothing in usable acceleration through the lower gears, only flat out in the higher gears will a much higher top speed be really noticeable.
It may post spectacular dyno numbers, but be temperamental, peaky, laggy, much harder to ride, and no quicker on a very tight road race circuit.
There have been no successful turbocharged sports bikes put into production, and for very good reasons, and not because it has never been tried.

After about forty years of personal turbocharging experience, I wonder if it is really the right approach for a Locost type of vehicle ?
Not that I don't like turbos, I certainly do, but they would be far more suitable for a four cylinder street driven door slammer with yards of sheet metal, than a featherweight spider framed performance oriented Locost.

A screw supercharger would be a much better approach for our type of driving.
That is how the Ar-i-el At-om gets its 450Hp, and that is a very serious bit of kit....
Very fast engine acceleration and razor sharp throttle response is what is needed for our little cars with potent mid range torque.

I agree, and a kit is available to fit an Eaton M62 in a Miata giving @250 hp with the right exhaust.
Here's a guy http://forum.miata.net/vb/showthread.php?s=0940bf888cb83ec71a8ef99ded5a4e75&t=421654 that jumped up to an MP90 and hit over 300hp at ~25 lbs of boost (with dyno screen shots).
You'll notice that he crosses 250 tq at ~3500 rpm with the HUGE exhaust and never goes back under that number.

IMHO, turbos have gotten a bad reputation by kids fixating on - and designing for - peak power. Oh sure they get 500+ hp, but the power curve is flat until 5000 rpm, then shoots straight up, making the car's road manners totally unacceptable for anything but drag-racing.

It doesn't have to be that way...

Here's a turbocharged 2.4 liter Honda I built up for my car last year. Note the torque curve, 275 ft-lbs at 3200 rpm and holds that until 7300 rpm. Boost is a mild 9-10 psi. A supercharger loses efficiency at higher rpm, where it's overheating the air which has to be bled off. That can been see in the supercharged engine above, where torque peaks at 4200 rpm and drops off about 30% by 7000 rpm. Having high torque at low rpm is of little use in a light car such as a Locost, where low speed wheelspin is already the limiting factor. All a supercharger does is make more tire smoke. And up at the high end, where power can be put to the ground, the supercharger is on the downhill side of its efficiency curve, and the turbo is just getting started.

Supercharged engines are also louder because they effectively raise the compression of the engine yet offer no muffling, plus they add more noise themselves. A turbo setup is a natural muffler, muffling both the exhaust and the inlet.

Between a wide torque curve and lower noise, I think my engine will hold its own.

There are limits. No doubt about it. But if you know where these limits are you can be reliable. I ran my aba 8v VW engine all summer at 300whp because we knew anything more then that was pushing it. The last race day of the year We had the engine running 373 whp and finally killed it. I had a lot of fun with $105. Would buy again