Discussion in 'Chevy' started by blainepga, Mar 25, 2014.
Or you could just use a turbo which make that all so easy and is more efficient to boot.
Superchargers are nice in cars as they work from zero rpm.
My dad bought a small turbo car in the early 80s. It was decidedly lukewarm till about 2000rpm then all hell broke loose as the torque tripled over a few hundred rpm. T3 turbo on a 1.3litre ohv, no wonder it was laggy. An aircraft doesn't mind the peaky characteristic of a turbo as prop loading torque varies with the square of revs. Add in automatic altitude compensation and higher efficiency and the choice should be clear.
Yes, but where's the fun in that . Playing mechanical what-if is one of my hobbies.
Having said that, I would be happy to drive around behind a home-made CVT driven supercharger, but I don't know about flying behind one ( until someone invents a way of parking on a cloud).
Today, with variable geometry turbos you can have peak torque down around 1400rpm and keep that figure to near redline. It just feels like a much bigger engine.
I will show you what I am putting in my grocery getter this week. I have a '97 Mitsubishi Mirage with 280 k miles on it and still gets 30 plus mph. I am not a turbophobic. I have customized a new 1.8L motor going from the stock 114 hp to 400 hp. Also a completely new drive train. It is internally adjustable from 8 psi to 30 psi. It has a new Crower cam, new aluminum adjustable rocker arms, and I am finishing modifying the intake system. The stock injectors are 214 cc's and the new injectors are 650 cc's. There is a new fuel rail for these injectors and a new fuel pump at 105 psi with a new regulator and auto fuel return. This regulator is connected to the intake manifold with a stock setting of 43.5 psi that will go up accordingly with boost pressure. The stock throttle body was a 53 mm and the new one is 80 mm and (It wouldn't let me use the word I wanted so here is the substitution) really neat, ha ha! This is just for fun. You know how it is when you are getting on the freeway and the guy behind you decides he is going to go around you and cut you off. Well, all I want him to see are my tail lights, and then ask him how he likes his 80 k BMW or whatever.
Anyway, I will post some pictures this week. This doesn't have anything to do with my airplane, just thought I would let you know.
I do have the software to modify the ecm for this application. The ecm and tcm are in the same module.
I flew behind P&W supercharged engines and the superchargers work just fine. They also had "pressure carburetors" which were in many respects early throttle body injectors.
Hey, ya gotta enjoy life. This is a great way to do it!
They flew terribly and you were lucky to get out alive! ... I never said.
If there is something technically incorrect with what I wrote, your submission is most welcome.
Well on the P&W's it was easily possible to over boost the engines at takeoff unless you had a very high density altitude. In fact if you didn't know what you were doing over boost could be virtually guaranteed. Generally you had to worry about over boosting until somewhere around 13,000ft. Of course with a waste gate that concern goes away. As far as inefficiently wasting power driving the compressor just to vent the air, that would be true certainly at takeoff but after reducing power for climb could at worst be mitigated and with some thought about the power actually needed, most likely for normal circumstances eliminated. Keeping essentially a stock setup except for the pulley and waste gate at the expense of having to do a little thinking seems like a prudent approach. The normal power needed for climb could be worked out in advance for several density altitude scenarios and printed on a chart. Since you have a waste gate in an ab-normal or emergency situation just let it vent the excess pressure and drive.
The responses I have received on this post have generated more conversations than I anticipated. Please keep sending your opinions because the more information we have leads to better execution of a project like mine.
Exactly Blaine, that's what forums should be about.
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