An idea I haven't heard before. Will it work, or blow up.
Here is an idea, it would require extensive fabrication, but if it worked would kick a**. Build an engine to fairly high compression, lets say 10:1. Now put a torbo on it to give it, say 20 lb of boost. You are going to have to run race gas, but what if you want it as a daily driver too? here's the idea. put an electricly operated clutch between the exhaust turbine and the compressor, or, some way to route the exhaust around the turbine, or let intake air bypass the compressor, whatever. Just so you can turn the boost off or on. Now, the same switch that turns the boost off and on runs a valve in the fuel line to switch you from the pump gas in your regular tank to race gas in a seperate tank. If you needed to you could even set up a rats nest of relays to switch ECU's. What would you have to do to make this work? Why have I never heard of this being done before? Would the cam be a problem, or is there something that would be acceptable to both natural and forced induction.
Most turbos can do that (kind of). I think you can do it with a boost controller and an electronic wastegate (in most turbos). So you can run 10psi of boost, push a button on the boost controller, the wastegate closes, and you have 20 psi of boost. 10:1 with a turbo is cutting it close. Hope this helps, Tony
i have seen this done before. an old MG that some guy tricked out. he rebuilt a f*rd escort engine and added a centrifugal supercharger with an electric cluth from an A.C. compressor. i was sceptical at first about it running without the supercharger rotating, but i rode in the car and can tell you the little thing performed! he boasted some 23mpg with the supercharger off (fuel injected BTW).
the wastegate on a turbo does just this, it bypasses the exhaust gasses around the turbine so that when it gets to some boost level it stops compressing the air. there are a lot of electronic ones now that you can control with a knob from the drivers seat or you can have either a boost controller or the ECM control it.
I think that were someone to do this with a large motor (V8) that 10:1 is a bit much.
BW
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Bob Wooten
71 Camaro, 91 EFI
r71chevy@earthlink.net
www.r71camaro.homestead.com
I thought for sure somebody would make a turbo or supercharger that could be turned off or on, that wasn't really what I thought would be unique about the system. lets say the compression in the engine is 8.5:1. With the boost off you could run 87 oct. but you'd better leave the boost off until your next fillup or your going to destroy the engine by detonation. If you run 92 oct. in it all the time your wasting expensive gas when you could be running on the cheap stuff. Thats why I was thinking about a valve in the fuel line. depending on compression and boost you could set it up to switch between 87 and 92 octane or go all out and switch it between 92 and race gas. I think you would have to switch ECU's too to get the spark timing right. Built correctly, it could all be done form a single toggle switch on the dash, maybe even while driving though I wouldn't try it on my dollar.
OK a good idea yes. But you will need to come down on the compression ratio. You try to pump 20 psi turbo into a 10/1 can you say spun bearings, cracking the crank and sending the piston through the crank case?
ANY TURBO MOTOR FOR THE STREET NEEDS TO BE AROUND 6-7.5 TO 1 at the most. Now this is the reason I want to build a small turbo motor for the power for the race but tame for the street with a boost controler. At the strip od in a "race" situation you can pump up the boost and have the power. For cruising have it set to 3-5 PSI and you can happily live at 20 something MPG.
Now the way that blow off valves work is they actually release the boosted air from the outlet housing. If they vented exhaust gas the EPA would ban them.
But beyound the inetial cost of the turbo and fabracation a turbo is very reliable when hooked up right, given a fresh stream of cool oil, allowed to idle before engine shut off and allowed to run idle at start up as well. Checked regularly it can live a long life.
<font face="Verdana, Arial" size="2">Originally posted by Camaro_hunter_d: ANY TURBO MOTOR FOR THE STREET NEEDS TO BE AROUND 6-7.5 TO 1 at the most. </font>
Woah there is a falicy.
If you are running 20psi then you are probably racing the car. Use race gas and keep the compression around 8.5-9.5:1. Good throttle response on the street. Makes the car enjoyable instead of standing on the throttle to get it to go anywhere.
sorry guildo but hello this is a TURBO motor. If you go around with high comp pstons you will blow them out...FAST.
And I have seen some fast pick up turbo(yes they were import but it is still the same) and had 6.2/1 and they picked up at 1900RPM and the turbo peaked at 2900RPM. I have also seen a high comp 8.2/1 with a 15 PSI turbo blow the connecting rods through the block...
And yes if you use race gas you might be able to run higher comp but with gas prices at 2.07 gal for 92 oct here who the hell can afford race gas to run on the street. The main reason on getting a turbo is to have the power for the street when needed, and be able to get the high MPG when not in use because they can be esentially "turned off".
Not tring to knock ya or anything but....
And Guildo I have seen cars that have the capibilty to run 32 PSI driven on the street just so they can make the big american "egos" look really foolish by a small engine.
