why don't ppl do this...

SwolenColen · #1 (**permalink**) 07-05-2005, 10:11 PM

I was thinking... the worst part about turbocharging is that you have to choose between less lag and upper rpm power - unless you set up your system so that you have 1 second + lag, and don't reach full boost until nearly redline, you will build up backpressure in the turbine and lose power top end, which sucks for racing b/c upper rpm is where you live

So anyway - I think I found a way to help get the best of both worlds; it seems like ppl would have thought of this by now so I'm wondering if there is something about this that would not work - only route about half of the exhaust gasses through the turbine. For example, if you have a 3.0 6 cyl, have 3 cyl go through the turbine, and have the other three join straight into the downpipe. Then just mount a small turbo (.48 or something) to the first three. This way, you could make the turbo a little too small for the amount of gasses its taking (fast spool, normally would kill top end), but the backpressure would only cut off half the power that it normally would if you wanted the same throttle response while routing all gasses through the turbo. The only two problems I see with this are 1) making the manifold / downpipe and 2) varying backpressure for different cylinders (i don't even think this would be a problem, but you never know)
even better - if you could find a motorcycle turbo or something, and just get a big compressor on it, you could run it off of one cyl. and you would lose barely anything... anyway thanks for your opinions

Jason_M3 · #2 (**permalink**) 07-05-2005, 11:32 PM

I imagine it would mess up the flow of the engine. The exhaust would be a lot more free-flowing that than turbo and it would cause some crazy port area backlog imo.

Rage\ · #3 (**permalink**) 07-06-2005, 02:50 AM

What about the exhaust pulses?

VASHEE · #4 (**permalink**) 07-06-2005, 04:52 PM

that would not work because you have half of the engine working to support the turbine which is slowing exhaust gasses and keeping more pressure in the cylinder, while u have the other half of the engine free flowing. Half of the cylinders would be running slower than the others and that would not mix. Im guessing something bad would happen to the crank because the slower cylinders would throw of the balance of the engine.

gol10dr1 · #5 (**permalink**) 07-09-2005, 12:55 PM

not to mention it would grossly reduce power with a turbo that small,

M50_328is · #6 (**permalink**) 07-12-2005, 01:16 AM

I posed that same ? about a year ago, I have a T3 laying around that is good for about 250 HP +/- and thought of using 3 cyl. I got laughed at too lol Too bad there isnt a effecient way to do that. What about Doing a small turbo i.e. T3 w/ 40 trim or something, to help low and midrange power, kinda like TT cars such as the Maserati BiTurbo, Supra, VR-4's etc. on all 6 cyl? Then when max boost is reached around 4-5k rpm, it simply bypasses the turbine. It would be like a TT setup w/ only 1 turbo ??? Flame suit on lol

~Phil

tjn182 · #7 (**permalink**) 07-13-2005, 04:37 AM

It wouldn't work. There wouldn't be enough exhaust gasses to power the turbo. If you had a small enough turbo to be powered by only 3 cylinders then it would be too small to power the entire engine. Not to mention it would cause some weird stuff w/ the exhaust - half the engine would have different backpressure than the other half - that along w/ other properties would cause one weird acting engine.
Good thought, but it wouldn't work.

queenz · #8 (**permalink**) 07-13-2005, 08:53 AM

Quote:

Originally Posted by M50_328is

I posed that same ? about a year ago, I have a T3 laying around that is good for about 250 HP +/- and thought of using 3 cyl. I got laughed at too lol Too bad there isnt a effecient way to do that. What about Doing a small turbo i.e. T3 w/ 40 trim or something, to help low and midrange power, kinda like TT cars such as the Maserati BiTurbo, Supra, VR-4's etc. on all 6 cyl? Then when max boost is reached around 4-5k rpm, it simply bypasses the turbine. It would be like a TT setup w/ only 1 turbo ??? Flame suit on lol

~Phil

where in MD are u from.. i never meet u before?/

P4g4nite · #9 (**permalink**) 07-14-2005, 05:43 AM

Later RX-7's used two different sized turbos in sequence, one smaller at lower RPM then a larger one later in the range.

M50_328is · #10 (**permalink**) 07-15-2005, 10:41 AM

Quote:

Originally Posted by queenz

where in MD are u from.. i never meet u before?/

I live near Frederick, I'll be hitting up the East Coast Euro meet next friday.
~Phil

markley02 · #11 (**permalink**) 07-15-2005, 11:29 AM

I dont think the exhaust would be as big of a deal as the balancing of the crank as said before. It would need one hell of a counter balance and that would make a lot of rotating mass. Just like P4g4nite said, this is why we have twin turbo cars. (which arent exactly twin turbo, but a small turbo is used to spool a bigger turbo)