kretos

me and my freind are both curious if its possible to supercharge and turbocharge an engine.

TraviZ

iTrader: (2)

sure, but completely useless, you woulld just feed the intake from the turbo into the supercharger or vice versa

kretos

yeah i kinda figured its just overkill

dankhound

Might as well add some nitrous just for fun. 3 power adders on one car would be pretty cool.

rhuarc31

Actually, it's not a total waste of time, it's similar in theory to some of the twin turbo set ups that use one turbo to feed another. Been done with pretty good success on diesels as well -turbo into a roots type blower.

biggtime

Actually was done years ago by rick dobbertin. here is a pic

89JYturbo

Here is a rig that has done it successfully:

V12 Detroit Diesel, Four Turbochargers pumping into two roots style blowers

12.01@114mph!

89JYturbo

stu

Once the turbo produces more boost than the supercharger, the supercharger will just free wheel. So the Superchager can give you the small boost you desire at lower rpms, but I'd just as soon use a small shot of nitrous to speed up the spool instead.

Using nitrous would likely be a cleaner set-up, not to mention it'd save a lot of space. Also, you wouldn't always have to use the nitrous if you didn't want to. You can stay off the juice and out of boost easier, so you could potentially achieve decent gas milage while you're not stomping people on the streets.

iansane

iTrader: (1)

I saw that on an r33 skyline awhile back. HUGE freaking turbo and a supercharger to help spool it up initially.

stu

The supercharger doesn't directly help spool up the turbo, it's just there to pick up the slack before the turbo starts making boost. It does however, add more flow through the motor, which helps the turbo I guess, but not like you are thinking. Especially since a supercharger doesn't reach full boost right away anyway.

dankhound

Those are two strokes. They need the blower to run. The turbos are for added power.

I think a better setup on our cars would be two different sized turbos. You can have a smaller turbo that spools quickly on one bank and a larger one that spool slowly on the other bank.

SATURN5

The idea has crossed my mind....

stu

That's essentially just a sequential turbo set-up, like the Supras and RX-7s. I'd avoid this set-up, as it will just be a solenoid nightmare better left for the factory to design. Besides that, you are missing an important point. You know how people install an H-pipe or cross pipe to even out the flow of dual exhaust, and make them sound better? Well, you'll have to do the same thing with the exhaust manifolds for this kind of set-up. You can't have completely different back pressures for each head, that'd never work; so you would have to run some sort of H-pipe type deal to connect and even out the back pressure between both exhaust manifolds. That's easy for a Supra (inline motor) or an RX-7 (rotory) but I don't even want to imagine the nest of piping you'd have to have for a V engine. Unless you put the turbos right next to each other or something.

bygblok

iTrader: (3)

back in the mid eighties one of the original pro-street/engineered cars was built by a guy named Rick Dobberton. It was a Pontiac J2000 with a blown twin turbo small block chevrolet. Had so much tire under it the chunk for the rearend was only wide enough for the center section. It was a cool ride but terrible as far as overkill.

biggtime

Read 10 posts up

89JYturbo

I would think that different backpressures on each bank would pose a problem too. But some how Saab drove the turbo off only the front bank on the V6 9-5. Of course Saab was also the company tinkering with variable compression engines (the whole cylinder block would pivot away from the crankshaft to lower compression as boost came in, then pivot back to raise compression for good off- boost response). I'm not saying we should run a large and small turbo on a v8 though.

bygblok

iTrader: (3)

Actually the pic you have is of his 1964 chevyII, not the later model J2000 he built in 1985. I saw the debut of the Pontiac at the Hot Rod Super Nats in Indy that year. It was pretty cool because the car had a frame and so did the body. All polished chrome moly tubing and even with the FULL body tilted up off the chassis(like a funny car) the doors would still open. I liked the ChevyII better from a purist standpoint but the Pontiac was truly a piece of overkill at the top of the food chain!!!!

biggtime

Yes I know what car it was i was just pointing out that we already covered rick's twin, blown, nitroused

dankhound

Back pressure wouldnt be a giagantic problem. The problem would be keeping the smaller turbo from overreving, or bleeding boost.

stu

That's what wastegates are for.
Here, I recently saw some diagrams of a sequential turbo set-up, let me go find it.

stu

Here. Noticed how the manifold is joined?



Here's a more detailed diagram. The first one is a Supra I believe, and the second one is an RX-7 I think.


89JYturbo: Are you sure that Saab only ran the turbo off of one bank of cylinders? Maybe you just didn't notice the connector pipe. I don't even see why they would do that, it'd be such a waste of energy to try and spool the turbo with only one bank.

dankhound

If you saw the size of the turbo youd see how it could spool off three cylinders.

89JYturbo

Boy, that borders on an insult to my 'intelagince'.

I'm sure what I stated is correct. The way Saab sees it, it's revolutionary! Not saying I agree, just that Saab does indeed do this.

http://www.saabcentral.com/features/...0_saloon_2.php

nightrider87

that pic of the supra turbos, the first one. How is that sequential? I must be missing something but it just looks like they both get air from the same tube, and the compressor outlets exit into the same tube feeding the throttlebody. One doesn't feed into the other... That's just like using two turbos instead of one off the same manifold...

This is what it looks like to me...i'm missing something i presume?

Dustin Mustangs

iTrader: (1)

I guess it depends on what sequential means. Nightrider, I think you are talking about what I would call staged turbos, like for tractor pulling. The pic below is simple diagram of this. The above images, well at least the first one, are of setups designed to use two different sized turbos. One for low rpm spool-up and one for high rpm power (is that called sequential?). One wouldn't feed the other like in a staged setup though.

Dustin Mustangs

iTrader: (1)

Whoops:

Kingtal0n

Say, once the little turbo runs out of breath I assume the bigger turbo has already kicked in... but does the air basically speed through the smaller turbo at that point? I mean are the adiabatic losses still imposed at all through the smaller turbo, since its still spinning obviouselly but no longer in control of the acceleration of the air, it should be 100% Adiabatic efficienct at that point right? only problem then is the restriction it presents to the exhaust manifold correct?

Synapsis

To help with the illustrations, here's the setup I have on my VW. It's from a 1992 Mazda Cosmo sequential twin turbo:

And yes, it's a cluster **** of vacuum lines.

The primary turbo produces ~ 10 PSI boost until around 3000 rpm and drops off a little, then the secondary turbo opens and produces boost up to 8000 rpm.

Dustin Mustangs

iTrader: (1)

That's a really interesting pic, and I guess it clears up what sequential turbocharging is.

Synapsis, is that a factory or aftermarket setup and what is the manufacturer? Also, can you feel the transition between turbos?

Synapsis

That's a factory 93-95 Mazda RX-7 and Cosmo setup. I don't have my 13B-REW running yet, but from I've been told you can feel the first turbo taper off a little before the second kicks in.

The turbo setup with the wastegate and precontrol valves disassembled is in the middle center of this pic.

Dustin Mustangs

iTrader: (1)

RX7....is that rotary?

stu

Yes, RX-7 is the rotory.