Help understanding turbos/twin turbos

[Meeblek]

I've owned/ripped apart/reassembled a few cars in my life but never a turbo. I would like to get straigtened out about a few things.

1. The way I understand turbo is that exaust gases turn an impeller which is used to compress air. This compressed air is then run through an intercooler (if so equipped) and then forced into the cylinder. More air = more gas = more power. A supercharger uses a belt system off the crank intead of exhaust gas to compress air. Is this right? If so, wouldn't it be simpler to use an electric compressor? Or would such a device use too much power?

2. How do twin turbos work? Do they 'double compress' the original charge from the fist turbo? (air goes through turbo #1, is compressed, then goes through turbo #2?) or does each turbo (in the case of a Skyline) feed 3 cylinders? If the latter is the case, is the reasoning behind this the same reasoning why more carbs = more power? (air goes faster through a bunch of smaller holes than through one hole with the same cross section).

3. Turbo lag. Is this caused by the time delay from when you hit the throttle to the time it takes for the exhaust gases to get the turbo impeller moving fast enough to deliver peak compression?

4. Intercoolers. I understand that these cool the compress air charges that are being sent to the engine (lower temperature air = more fuel can be held in solution). Is this correct?

Finally, are there any resources on the internet that explain indepth how turbo systems work? (not a simple as howstuffworks)

Thanks!

[PlatinumShift]

Re: Help understanding turbos/twin turbos

I've owned/ripped apart/reassembled a few cars in my life but never a turbo. I would like to get straigtened out about a few things.

1. The way I understand turbo is that exaust gases turn an impeller which is used to compress air. This compressed air is then run through an intercooler (if so equipped) and then forced into the cylinder. More air = more gas = more power. A supercharger uses a belt system off the crank intead of exhaust gas to compress air. Is this right? If so, wouldn't it be simpler to use an electric compressor? Or would such a device use too much power?

2. How do twin turbos work? Do they 'double compress' the original charge from the fist turbo? (air goes through turbo #1, is compressed, then goes through turbo #2?) or does each turbo (in the case of a Skyline) feed 3 cylinders? If the latter is the case, is the reasoning behind this the same reasoning why more carbs = more power? (air goes faster through a bunch of smaller holes than through one hole with the same cross section).

3. Turbo lag. Is this caused by the time delay from when you hit the throttle to the time it takes for the exhaust gases to get the turbo impeller moving fast enough to deliver peak compression?

4. Intercoolers. I understand that these cool the compress air charges that are being sent to the engine (lower temperature air = more fuel can be held in solution). Is this correct?

Finally, are there any resources on the internet that explain indepth how turbo systems work? (not a simple as howstuffworks)

Thanks!

1. Yes that is how it works, people have tried to use electric ones, you can actuall buy ones that will force up to 1psi. The problem with this is I dont think you can have such small fan blades push any higher psi.

2. A 'Twin Turbo' splits the engine in 2 and runs one turbo for one side and one for the other. Or in the case of an inline, front and rear cyl. What you are thinking is called a 'Twin Charger' where it would use a smaller turbo to spool up the bigger turbo to reduce lag

3. Turbo lag is the time it takes from the turbo to the intake to compress with air, people usually mis consieve(sp?) lag as the time it takes the turbo to spool....thats called 'Turbo Spool' lol

4. Yes.

5. Yes, google it.

I hope this helps

[spd-dmn]

A great resource for turbo information is Maximum Boost, authored by Corky Bell.

ISBN: 0837601606

[MoxMonkey]

http://auto.howstuffworks.com/turbo.htm

ooooh pictures and uber noob friendly

[RobStar86]

I'm fairly certain a "Twin Turbo" is just having 2 turbos. The term "Twin Charger" refers to having both a super charger and turbo, super charger builds boost until the turbo hits boost. Allows you to run a much larger turbo since the supercharger handles the bottom end of the rpm's and saves the turbo for the higher revs.

When one smaller turbo feeds a larger turbo is called Sequential. Like a third gen Mazda RX-7. Sequential Turbo setups are much less laggy, almost no lag at all, but more prone to problems. That's why most 7 owners convert to a single setup (at least according to my uncle who owns a 3rd gen)

[Fr0sty]

I'm fairly certain a "Twin Turbo" is just having 2 turbos. The term "Twin Charger" refers to having both a super charger and turbo, super charger builds boost until the turbo hits boost. Allows you to run a much larger turbo since the supercharger handles the bottom end of the rpm's and saves the turbo for the higher revs.

When one smaller turbo feeds a larger turbo is called Sequential. Like a third gen Mazda RX-7. Sequential Turbo setups are much less laggy, almost no lag at all, but more prone to problems. That's why most 7 owners convert to a single setup (at least according to my uncle who owns a 3rd gen)

sequentiel turbo-charging is not problematic but costly that's it..

how many rx-7 in japan do the 1/4 in the mid 9's on street radial on twin setup alot


twincharge like you said is supercharger for low end + turbo for the high end but it requires some sort of clutch for the supercharger to de-activate it at high rpm when the turbo kicks in.. so its messy to tune those suckers


so the best solution to eliminate lag while still have some good outpout would be a stroker kit for me a good twin setup but any exotic solution can apply but theyd be hard to work on when things go bad

[leung23c]

1. The difference between turbo and supercharger/electric compressor is that it uses exhaust gas energy that would otherwise WASTED to drive a compressor. Supercharger uses crankshaft to drive, which slows the crankshaft turning: therefore it SUCKS. Electric compressor can hardly give you any boost, and if it does give you boost it will drag the alternator, which slows the crankshaft turning: therefore, it SUCKS. Turbo, instead, recover energy through exhaust gas, which in theory does not slow down the crankshaft. As a sidenote, it is important to mount the turbo as close to the exhaust as possible. Before the farther exhaust gas goes, it cools down, therefore losing energy. The hotter the exhaust gas through the turbo, the more energy recovered.

Yeah I just see the last post was in 2007 but it's too late for me to delete what i just typed.

[Dragon Humper]

Hmmm....I think just the mention of an electric turbo as a viable alternative justifies deletion.




Jon.