Twin Turbo Idea(Remote Activated Turbo)

[kingcolbert83]

turbo's already have cutout's. they're called wastegates. if (modern systems) the ECM doesn't need the extra boost, it opens the waste gate and the exhaust bypasses the impeller.
most, if not all, have a variable wastegate to modulate the amount of boost being delivered.
twin turbo's feeding their individual bank have to be precisely matched and tuned so the banks are running the same, EXACTLY the same.
if the turbo's are feeding into a common plenum it's much easier. i think you'd just have to worry about having the exhaust restrictions match at all times. i'd probably try to use a common wastegate actuation system.

I thought the wastegates are used to blow off excess boost pressure while under boost. Yea I could turn it down to like 1 or 2 psi but thats where the restriction comes into play because the turbos are restricting more than moving the air. Thats my understanding from reading and people that have done turbo setups. Thats why they say dont get too small a turbo because it will restrict the exhaust system and hurt more than help.

Is there a way to program or have the wastegates stay open all the time and then when I want to make power set them to the boost I want? I understand what you guys are saying and thanks for the input.

I know yall are saying that turbos only make boost under load but regardless of that they are still spinning. I was just trying to think of a system where I could have boost on demand instead of riding around with the boost on tap of the throttle. My thinking is that I would prolong the life of the turbo and the oiling system because it is not being run all the time. I dont need it all the time just when I want to have a little fun.

 

[Tuggy24g]

I would love to see a 305 have 500HP. I bet it could be done, but it would be a weast of money. You could do the same thing with a 350 and make it have 600+ and maybe get decent gas miles. anywhoo good luck and hope everything works out.

 

[megaladon6]

the blow off valve gets rid of excess pressure in the intake system, the wastegate controls the volume of exhaust flow to the turbo. it can cut it down to near zero. there are times you won't want max boost.
you can use an rheostat or a vacuum system/knob in the pass compartment to set the wastegate/max boost.
however, for the best driveability you really do need to have a good, boost referenced, EFI system. i don't think you could run a carb at all, since it won't be correct except in one specific set of circumstances. and you should have the ecm control the boost (you can still put a rheostat in the system to control max boost.) if you're cruising on the highway at 2k the "manual" turbo's will still be spooled and put out alot more boost than you want/need.

 

[kingcolbert83]

I would love to see a 305 have 500HP. I bet it could be done, but it would be a weast of money. You could do the same thing with a 350 and make it have 600+ and maybe get decent gas miles. anywhoo good luck and hope everything works out.

I could do that but why when I already have a running 305. This is just an idea im throwing around. Its either this, caddy 500 big block, or buick big block 430. I have two choices for the caddy motor. One is from a member for 500 and the other is local for 250. One from member comes with more stuff and is a better deal but I cant afford to really buy it. I was going to buy the 250 one and get parts as money allows.(it was running before pulled too) The buick motor is a very good deal and Im leaning more toward it because of that fact. Its already rebuilt with new crank, pistons, 455 heads, etc. He built it for somebody else but they never came through so he just wants his money back for labor. Wants 350 obo. I told him I will come check it out monday.

 

[DRIVEN]

Has anyone brought up timing? I read through the thread but only once - quickly. I also saw no mention of compression ratio. Engines built for boost are typically in the 8.0 - 8.5:1 range. They are low compression because the turbo/blower pressure effectively adds points. Compression ratio is where you get gas mileage and power. Most turbo/blower manufacturers advertise increased mileage with their kits. This is due to 2 things; higher compression and added low end torque.
I know from personal experience that an engine with too much compression and added boost burns pistons. I also know that an engine built for boost (low compression) and a bypassed boost source (beltless Paxton) gives you shitty gas mileage and less power. And that was on an EFI application - I can't imagine the headaches involved dealing with fuel and timing on a carb/distributor set-up.

My advice is to either build for higher compression and no power adders or build for turbo/blower and run it all the time as intended.

 

[SLICK79WGN]

here you go guys

GOT BOOST???

http://www.youtube.com/watch?v=_0ZoCCwo ... ed&search=

 

[87National]

You will run into enough headaches with any homebrewed turbo system. What you are proposing will add cost and time to the project with little or no benefit.

The cut-out system that you describes will only add a ton of complexity without adding any real benefit. Turbo motors don't build boost unless the motor is under load, so while cruising you get the same mileage as you would with no turbo at all.

The problem with a remote mount turbo would be if you have a leak on either the exhaust side or cold side, it will be much more difficult to diagnose.

If it were me I would keep it simple. While not perfect, people have had good luck with the $200 ebay single turbo manifold setups. Buy a good quality turbo, and decide if you want to go the carb or efi route. With EFI you can use megasquirt to control fuel injector pulse width. A carb would probably be easier and cheaper, but you lose the ability to fine tune your system like you would with efi.

Would it really be that complicated? Im only adding the electric exhaust cutout and running a downpipe on one side for the regular exhaust . The other side would be to the turbo piping. If I do any turbo it will be twin. I just like the sound of it I guess. 🙂

 

[87National]

I think it was also mentioned a few posts up, but you can buy an adjustable wastegate controller that can be adjusted while driving. This allows you to adjust the threshold at which the wastegate will open. You could then adjust on the fly from, say, 0 to 25 psi of boost.

 

[custom442]

The twins were talking about would be fed by each bank of the motor than ran into a single tube, then you carb or throttle body. they would be the same size. The other way of using a small and large turbo is all the exhaust feeds the small turbo then the already compressed air from the feeds the larger one then onto the carb o rthrottle body or i/c.
I hope that helps, i'm by no means an expert on this.

^^ this makes more sense. I was having a hard time wrapping my brain around setting up two turbos to the exact specifications as eachother and exact fueling, pipes, etc. I was told it wasn't easy and needs to be set perfectly to work correctly.

... on another note I never understood the idea of a twin turbo. How much power do you really need? One big turbo on a v8 with enough boost and a built engine should be able to reach 1,000 hp, no?

 

[foxtrot]

I'd like to see 25 lbs. of boost!

I've run up to 18, anything more than that is really tough!