Twin charged bp

[koRnhead]

If you find a supercharger kit off a Honda you could have a fun little bp. Don't twin it. It's a waste of your effort.
But for the guy above....if you try to blow a turbo into a m90 it will not bypass that boost. It will hit the rotors then stop and the m90 will try to shove the air into the motor. Now could that complex bypass system work with a totally custom intake manifold? Yes. But you will need to figure out your throttle body situation as that goes on the m90. So once your bypassing that your bypassing your throttle control as well!! That leaves ITBs off say a zx14 or similar high hp bike. And that is a whole new headache to make work. This is all way way more effort than a festiva is worth. We all know that.

[ZephTheChef]

OMG you are a fool!!! They can ban me for this post but I'm past caring.....trying to blow boost thru a roots style blower is a restriction. Plain and simple. A turbo and a m90 on a 1.8 litre bp is stupid. An m90 is not a great supercharger it's just not. Are they fun in a Wbody yes. Can you grenade trannys left and right with one in a grand prix of course......but that doesn't make it a great power adder. If it was every big power Wbody wouldn't be switching to turbos. And if they were so great you wouldn't be giving them away for free!!! It's a great paper weight tho. Kinda like a 4g64 crank from a 2g dsm.
Is it great to dream about some crazy ideas, sure thing....you asked what issues you would have doing this and what the reason was no one has done this....that's been answered here many times over.
You do not posses the technical know how to do this. Which leaves you one option to make it happen. Pay someone....Probably looking at 25 to 30 grand when all is said and done to have a goid shop do this for you. Congrats you will have the most expensive festiva worth 500 dollars in the history of festivas. I can only imagine how awesome that would be. Woohoo you win!!!!

We aren't talking about blowing a 16G through an M90, we are talking about utilizing the two power adders in completely different parts of the powerband. If you seriously think an m90 is a restriction when it's being turned by the engine then I believe you misunderstand the physics involved. It becomes like having an inline fuel pump in order to be able to operate to higher pressures. The two pumps see lower loading each, and will flow more fuel as a result. If the second pump had a bypass valve that would equalize the pressures on either side of it, it's current draw drops dramatically and it has little to no effect on the flow capacity of the primary pump...same thing if you shut it off entirely, except in that case it will minimally impact the flow. I have a LOT of experience with that scenario in the past and have done flow and current draw tests to verify.

W body guys go turbo for several reasons. Primarily because if you want more than 300whp, which is about the best you'll do driving an m90 and turning an auto trans, then you need a bigger power adder. Secondly, you can have an entry level turbo setup for the cost of a good intercooler and pulley setup for the m90, so the way those cars are set up it makes more financial sense to turbo. My argument would simply be that there's no reason whatsoever to remove the supercharger when you add a turbo. It is not a restriction like everybody and their mom says. It might gain you a negligible amount at the very top of the powerband, but you lose SOOOOO much area under the curve that it's not even funny. I don't know why you would think it would be a restriction, it is a spinning air pump all the time...and will move more air than a 16G can put out...and it has to do no work with the bypass open. Roots blowers are not twin screws...there is no compression within the housing so if you aren't creating a pressure differential by trapping that air, it takes very little power to turn the rotors. The engine itself is so much of a restriction compared to anything in the intake (supercharger, turbo, throttle body, etc) that it's not even close to reasonable to consider the supercharger a restriction, even if it were to be more restrictive than the turbo. If the engine wasn't the bottleneck then there would be no boost. If the supercharger was a restriction, you would have more pressure in the turbo to supercharger intake pipe than you would in the manifold, but guess what, that doesn't happen and I'll soon have the second map sensor in my Buick to prove it.

I don't think M90s are super great, just super great for what they are. My comment was relative. I have outgrown them on my car for sure, but for the $100 they go for these days, it is an incredible power adder, and I think there is huge potential for it on one of these cars (although again, I think it is way oversized). You are hating on this project because you think it is going to cost tens of thousands of dollars. I would be hating if thst was the budget too. But this is something we can throw together for under a thousand bucks plus stuff I already have laying around from other projects. Big 16G turbo...check, M90 supercharger...check. The turbo setup on the car is already roughed in...it's not that ridiculous a project. I have no idea where he would put the damn thing, it is definitely huge for that car, but we aren't talking about an expensive build here.

[ZephTheChef]

If you find a supercharger kit off a Honda you could have a fun little bp. Don't twin it. It's a waste of your effort.
But for the guy above....if you try to blow a turbo into a m90 it will not bypass that boost. It will hit the rotors then stop and the m90 will try to shove the air into the motor. Now could that complex bypass system work with a totally custom intake manifold? Yes. But you will need to figure out your throttle body situation as that goes on the m90. So once your bypassing that your bypassing your throttle control as well!! That leaves ITBs off say a zx14 or similar high hp bike. And that is a whole new headache to make work. This is all way way more effort than a festiva is worth. We all know that.

That's why I said bypass valve is an inaccurate term, it is a recirc valve. All the air goes through the rotors, some of it bleeds back into the inlet to null the pressure differential when the bypass is open. My point is the supercharger eats more air than the turbo spits out so the turbo isn't having to push the supercharger, the supercharger ends up just sitting there having little to no impact whatsoever...it takes the air in the inlet, spits it into the outlet, it has nowhere to go because the engine isn't eating it that fast, so it goes through the recirculation valve back into the inlet for no significant net pressure change. The air delivery between the supercharger and the engine is in excess of that of the turbo to the supercharger, so the supercharger is not going to have an effect on the air delivery capability of the turbo. The engine is the limiting factor by such a large degree that the supercharger may as well not be there when in "bypass" mode.

[koRnhead]

You sir clearly do not understand how twin charging something works!!!! I am well aware an m90 will flow more then enough air....the question is what do you do with it when you want the turbo to take over and make all the boost???? You can't blow 20psi from a turbo into a m90 and expect it to just work. It doesn't work that way. Could you give him that m90 and could he make some adapter plate and slap it on. Sure....bur trying to compound boost that thing with the m90 and a turbo won't work.
The whole point of that is to blow into the giant sized turbo to spool it. Can't do that with a roots blower. If you really have all this experience with boost you would know this and not need it explained to you like a 1st grader.

[ZephTheChef]

Also, there is no reason you can't blow the m90 through the turbo, or blow both of them through the throttle body. There's no rule that says your throttle plate needs to be pre-supercharger.

[ZephTheChef]

You sir clearly do not understand how twin charging something works!!!! I am well aware an m90 will flow more then enough air....the question is what do you do with it when you want the turbo to take over and make all the boost???? You can't blow 20psi from a turbo into a m90 and expect it to just work. It doesn't work that way. Could you give him that m90 and could he make some adapter plate and slap it on. Sure....bur trying to compound boost that thing with the m90 and a turbo won't work.
The whole point of that is to blow into the giant sized turbo to spool it. Can't do that with a roots blower. If you really have all this experience with boost you would know this and not need it explained to you like a 1st grader.

You evidently don't understand the M90s recirculation valve.

[koRnhead]

So in your scenario you would need to spin that m90 over the boost pressure of the turbo you are running!!!!! Again if you know m90s so well you know that past a 17ish psi they make no more power just heat . You can intercool and e85 that girl she still won't make power. Only extra heat.

[koRnhead]

The recirculation valve in a m90 will not flow what a turbo can push for air!!

Again you are missing what he wants to do with it. Twin charging a car with a roots blower doesn't work well if at all. You need to use a centrifugal blower to make this work.

[koRnhead]

Again I ask how will you package all this inside a festiva engine bay??? Your gonna make a plate to spin the m90 off the side of a bp into a turbo and then into the motor?? Have you seen a bp inside a festiva??

[ZephTheChef]

The recirculation valve in a m90 will not flow what a turbo can push for air!!

Again you are missing what he wants to do with it. Twin charging a car with a roots blower doesn't work well if at all. You need to use a centrifugal blower to make this work.

Again, you are missing that the recirc valve does not allow the turbo to bypass the m90, it allows the m90 to recirculate its air. Power will still be delivered through the m90s rotors, they simply will be unloaded due to the lack of pressure differential across them created by the bypass valve. You also seem to be stuck up on the location of the m90. For all the car cares, I could run it off a separate engine in a chase car with a long intake pipe running to Bryan's car. It does not have to be on the manifold. The turbo does not necessarily have to blow through it, it could go the other way around. There are endless possibilities for combinations to make this work properly. I love internet fights.

[ZephTheChef]

Again I ask how will you package all this inside a festiva engine bay??? Your gonna make a plate to spin the m90 off the side of a bp into a turbo and then into the motor?? Have you seen a bp inside a festiva??

I am super doubtful about whether it can fit. I said that right off the bat. But the principles of operation are sound.

[koRnhead]

If you do what you are telling him to do. You are making the turbo useless 100% all your doing is blowing air into the case of the m90. So you lose the point of having said large turbo to take over boost duties. I will restate it you need to read up on twincharged systems.

[koRnhead]

You are correct the basic parts are not expensive to buy for this. I have an evo3 16g sitting in the garage a bp and an m90. Bur making it all work and fit and actually make a drivable car is not cheap. Figure in the year or two to make it happen you have a huge budget even if you do the work yourself .

[ZephTheChef]

If you do what you are telling him to do. You are making the turbo useless 100% all your doing is blowing air into the case of the m90. So you lose the point of having said large turbo to take over boost duties. I will restate it you need to read up on twincharged systems.

I HAVE a twincharged car. With an eaton and a very large turbo. I just finished it up and was getting the low and mid throttle tuned before I left for this week of meetings. I will be happy to, when I get back stateside, prove that it works just fine by doing some runs with the bypass open and logging turbo outlet psi vs manifold psi. If you're right, I'll have wasted a ton of time and money over the last year and owe you an apology.

[ZephTheChef]

You are correct the basic parts are not expensive to buy for this. I have an evo3 16g sitting in the garage a bp and an m90. Bur making it all work and fit and actually make a drivable car is not cheap. Figure in the year or two to make it happen you have a huge budget even if you do the work yourself .

Point granted. But I lump carbuilding into the entertainment category, not the work category, so it's as if I were playing video games all day. Can't put a lot of labor cost on that.