Turbo questions...

[Siliconslave]

Hey peeps,
I have a few questions about turboing a NA car, most of the "knowledge" i have is from reading stuff on forums, understanding the theory etc but i'd like to solidify some bits of it.

Firstly what do you need & what does it do, so far i think you need:

turbo manifold: exhaust port of engine -> turbo, does this usually include the turbo -> exhaust section too?
Turbo: i know/understand this bit pretty well
Oil feeds: keep the tubby nice and lubed up, do you generally have to tap into the sump pan?
ECU solution: replacement / piggyback to control fueling based on air pressure and what else? can they interface or replace a boost controller
Knock sensor: detect DET, generally needed? links to ECU solution or just cuts fueling generally?
wastegate: control boost pressure, set at static level or boost controller
dump/recirc valve: release pressure on closure of the throttle, where in the system do recirc/bypass valves feed the air back into?
Electronic boost controller: controls waste gate, feeds from air flow sensor and what else?

Other random questions: how easy is it to dynamically control boost levels? ie have one profile for pottering around town and one for ragging it around tracks.

What are the problems with "turning off" a turbo by setting the waste gate to open on zero pressure, i assume you'd get some reduction in MPG because of the back pressure on the engine from the turbo? but equally you won't be using so much fuel as your air pressure is lower...

Finally a good reference / book recommendation would be fantastic.

cheers

 

[Toker]

http://beesandgoats.com/boostfaq/g2icturbo.html

there's a nice guide.

you can easily switch between two maps, if it's a piggyback ecu you can switch between the two and if its an obd2 ecu you can have a tool which plugs in to the diagnostic port and can flash between the maps

 

[Sneaky Peaky]

Don't know anything about adding a turbo to a NA car but can have a stab at the random other questions.

I have an Apexi AVCR which allows a high level degree of control over the turbo and allows you to dynamically switch between 2 levels of boost control, 3 if you include 'off'

I don't think you can turn off the turbo as such as you will always have some boost depending on the actuator crack pressure. Mine for example will still run at approx 1 bar with the Apexi switched off.

 

[penski]

turbo manifold: exhaust port of engine -> turbo, does this usually include the turbo -> exhaust section too?

- Manifold goes from the engine to the turbo. Downpipe goes from the turbo to the exhaust (or just straight out the nearest body panel if you're feeling kinky )

Turbo: i know/understand this bit pretty well

Oil feeds: keep the tubby nice and lubed up, do you generally have to tap into the sump pan?

- Take a feed from a handy oil line using a T-piece and have the drain from the turbo tapped into the sump, mavity only.

ECU solution: replacement / piggyback to control fueling based on air pressure and what else? can they interface or replace a boost controller

- I'd go with Megasquirt and Spark for DIY - can have multiple maps and can interface with controller.

Knock sensor: detect DET, generally needed? links to ECU solution or just cuts fueling generally?

- With MS&S I would want to get as many sensors as possible...Just so you know exactly what your engine is doing.

wastegate: control boost pressure, set at static level or boost controller

Let the controller deal with it. Set low to start with.

dump/recirc valve: release pressure on closure of the throttle, where in the system do recirc/bypass valves feed the air back into?

- Back to the intake side of the turbot.

Electronic boost controller: controls waste gate, feeds from air flow sensor and what else?

- Brews a good cuppa.

Other random questions: how easy is it to dynamically control boost levels? ie have one profile for pottering around town and one for ragging it around tracks.

- With the right ECU, easy.

What are the problems with "turning off" a turbo by setting the waste gate to open on zero pressure, i assume you'd get some reduction in MPG because of the back pressure on the engine from the turbo? but equally you won't be using so much fuel as your air pressure is lower...

- Just set your 'low' map to 4-6psi.

Finally a good reference / book recommendation would be fantastic.

Turbocharging by Corky Bell.

*n

 

[Firestar_3x]

Finally a good reference / book recommendation would be fantastic.

Turbocharging by Corky Bell.

*n

Really is a fantastic book, when i was building a homebrew turbo kit this proved very usefull.

 

[penski]

Really is a fantastic book, when i was building a homebrew turbo kit this proved very usefull.

EVERYONE thinking of doing work on cars needs that book along with this and Vizard's A-series book...Along with his 'build horsepower' one.

*n

 

[Firestar_3x]

Anything on building chassis Penski?

 

[Lashout_UK]

Maximum Boost, eh.......

Some good material but don't use it as the be all and end all. There are some very debatable bits in it but it is useful and has some good pointers and guides on general setting up/construction

Lots of useful pointers here and what to read:

http://retrorides.proboards86.com/index.cgi?action=display&board=general&thread=25682&page=1

 

[DreXeL]

turbo manifold: exhaust port of engine -> turbo, does this usually include the turbo -> exhaust section too?

Turbo to exhaust section is called the downpipe and is seperate from the manifold. You usually buy the two seperately, but you can buy matched manifolds and downpipes that work with each other.

Oil feeds: keep the tubby nice and lubed up, do you generally have to tap into the sump pan?

Yep, usual way to do it is to remove stock oil pressure sensor, install T-Piece for oil feed line and sensor. You can also use a sanwhich plate between the oil filter. Oil return goes into sump, as high as possible on the side of the sump. Purely mavity fed, you have to ensure no kinks etc.

ECU solution: replacement / piggyback to control fueling based on air pressure and what else? can they interface or replace a boost controller?

The ECU controls fuelling and ignition timing, it can measure the air coming into the engine using either MAF (mass air flow), or MAP (pressure). MAP is more reliable and simpler as you don't have a delicate MADF sensor in the intake behind the air filter. Some ECUs can control boost, and in this case you would not need a boost controller.

Knock sensor: detect DET, generally needed? links to ECU solution or just cuts fueling generally?

Not neciserrily needed, but helps with safety. When a knock sensor connected to the ECU, the ECU 'listens' for det, and retards timing to reduce the detonation. It doesn't cut fuel. You can also have a knock sensor connected to a visable readout like a Knock Link, to you can see when there is any det.

wastegate: control boost pressure, set at static level or boost controller

Yes, the wastegate can control boost without a controller, you just use the required spring strength to change boost pressure.

dump/recirc valve: release pressure on closure of the throttle, where in the system do recirc/bypass valves feed the air back into?

Back into the intake before the throttle.

Electronic boost controller: controls waste gate, feeds from air flow sensor and what else?

No, it doesn't feed from the air flow sensor. Basically you feed a vac line from somewhere in the intake (inlet manifold, nipple on turbo compressor), through a solenoid electronically connected to the boost controller, and back to the wastegate inlet nipple.

Other random questions: how easy is it to dynamically control boost levels? ie have one profile for pottering around town and one for ragging it around tracks.

Yes, most EBCs allow two or more set boost levels.

What are the problems with "turning off" a turbo by setting the waste gate to open on zero pressure, i assume you'd get some reduction in MPG because of the back pressure on the engine from the turbo? but equally you won't be using so much fuel as your air pressure is lower...

You can't turn it right off, you are limited by the wastegate spring pressure.

Finally a good reference / book recommendation would be fantastic.

cheers

'Maximum Boost' by Corky Bell.

EDIT: Damn, beaten. I had this thread open and ready to reply whilst I had my lunch

 

[Firestar_3x]

Some good material but don't use it as the be all and end all. There are some very debatable bits in it but it is useful and has some good pointers and guides on general setting up/construction

Lots of useful pointers here:

http://retrorides.proboards86.com/index.cgi?action=display&board=general&thread=25682&page=1

I'd remove that link mate, the book should be paid for

 

[Lashout_UK]

Pah, fair cop

I have my own copy, by the way......

I prefer this one:

http://www.amazon.co.uk/Forced-Induction-Performance-Tuning-H691/dp/1859606911/ref=pd_sim_b_img_1

Better 'general' book in my opinion Does require some understanding of the principles, though but does cover them briefly if unknown.

 

[Siliconslave]

Great information there guys thanks the beesandgoats link is a nice overview and the Bell book i've certainly heard of before will pick up a copy (thanks lashout )

whats the deal with rocker cover breathers on turbo cars? are they really needed?

 

[Firestar_3x]

You need to watch the rocker cover, depending how much PSI you run the standard PCV valve can be usuless since it allows the crank case to pressurise.

All depends on the engine really but i ended up running vent to atmos on the mazda.

 

[GeX]

the oil return should be at least 1/2" and fall off at angle of around 45deg back into the sump.

you also may want to look at dropping the compression ratio.

 

[penski]

you also may want to look at dropping the compression ratio.

Why would you want to do that? This isn't the early eighties.

*n

 

[GeX]

because modern engines n/a run rather high compression ratios, and if you look at them compared to turbo'd engine then the turbo engine will mostly have a lower compression ratio. Manufacturers don't pick them numbers out of thin air (most of the time).

 

[penski]

because modern engines n/a run rather high compression ratios, and if you look at them compared to turbo'd engine then the turbo engine will mostly have a lower compression ratio. Manufacturers don't pick them numbers out of thin air (most of the time).

Weird that...Because every time I've discussed the matter with people who design OEM turbo installations for a living, they have always said to leave the CR alone and design the rest of the system correctly.

With modern ECU design and knowledge of forced induction applications, lowering the SCR will achieve nothing but increase turbo lag.

Take a modern 2.0 16v N/A engine with about 150bhp. It may have a Static CR of 10.5:1 or thereabouts.

If you want to fit a turbo, you can either:

Keep the CR, use a well-designed and managed install and get a safe 300bhp with about 9-10psi.

OR

Lower the CR to 8.5:1 and get 300bhp with about 16psi....And a metric ****tonne of lag.

Why would you want to do the latter?

*n

 

[GeX]

because i don't know anyone who designs OE turbo applications, and am only looking at aftermarket turbo conversions. most of which include some way of lowering the CR. We're not talking about an OE install.

 

[penski]

because i don't know anyone who designs OE turbo applications, and am only looking at aftermarket turbo conversions. most of which include some way of lowering the CR. We're not talking about an OE install.

Neither am I.

Did you actually read my post?

*n

 

[Firestar_3x]

Depends on the engine and how much pressure you want to put through it but no need to lower the CR.