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Duratec 2.5 V6 - Turbo or Supercharger?
grazzledazzle - 26/5/08 at 10:14 AM

Anyone know of any projects that have turbo'd or supercharged the 2.5 V6?

I'm interested to see what's involved.


Paul TigerB6 - 26/5/08 at 10:14 AM

Noble did a twin turbo version of this didnt they??

this thread looks worth a good read through after a quick googling

[Edited on 26/5/08 by Paul TigerB6]

mr henderson - 26/5/08 at 10:23 AM

Generally speaking turbo charging is more effective and easier to control than supercharging. It's my personal opinion that most times when manifacturers choose supercharging they are doing so for marketing reasons (It's more posh and traditional)

With a v enginge one has to decide whether to use two turbos, one for each bank, or whether to use one turbo driven by both banks. If using the second apporach then the distance from exhaust manifold to turbo is going tobe further, so less effective and more space consumption.

Do you actually need to use the V6? If not, consider turbochaging the zetec, it has been done and very effectively too. Much simpler, less space needed, lots of power available

John

grazzledazzle - 26/5/08 at 10:29 AM

Thankyou chaps, i'm off to do some reading. DOn't know why my google search didn't show that up. Maybe i'm finally being censored!

I already have the V6 installed and looking for more power.

Paul TigerB6 - 26/5/08 at 10:38 AM

What have you got it installed in?? Any pics at all??

grazzledazzle - 26/5/08 at 10:46 AM

Hard to describe it really... Will get some pics sorted asap.

I can say it's front engine rear wheel drive running a 2wd cossie gearbox, so it can be done for those wondering!

jimmyjoebob - 26/5/08 at 11:07 AM

I would disagree that turbo charging is simpler than supercharging especially for a home brewed creation.

Fuelling, wildly variable boost, excessive heat, manufacturing of manifolds, relocating heat affected components etc for a turbo installation cause far more problems than when installing a supercharger.

clutch_kick - 26/5/08 at 11:36 AM

Twin turbo, use small units, with a high A/R turbine so it won't cause too much back pressure. Keep the boost low, approx 7psi, with intercooling or W/I it should give you an extra 25bhp but the increase in torque will be mind boggling.

With low boost you won't really need to lower the C/R unless the engine is HiComp. Just use GOOD fuel, 98RON minimum. A set of adjustable cam gears will see you gain an extra 5-8bhp, by advancing the intake by 3deg and retarding the exhaust by 2deg, but you will need to play about a lot with those setting on the dyno, those are just ball park figures.

It won't be cheap. It will give you a foul mouth by the time everything is properly set, but once you go turbo, you'll never go back. it's just plain addictive.

turbodisplay - 26/5/08 at 12:06 PM

Turbo charging adds less to fuel consumption. I`m making a cosworth v6 twin turbo, skline turo as primary, renault r21 turbo as a secondary. One/a pair of skyline turbos should be good for low lag due to ball bearing internals and ceramic exhaust turbine.
Darren

mr henderson - 26/5/08 at 12:16 PM

quote:
Originally posted by jimmyjoebob
I would disagree that turbo charging is simpler than supercharging especially for a home brewed creation.

Fuelling, wildly variable boost, excessive heat, manufacturing of manifolds, relocating heat affected components etc for a turbo installation cause far more problems than when installing a supercharger.


Who said it was simpler?? Not me, I said it would be simpler to turbo a zetec than the V6.

Installing a supercharger is comparatively easy as long as you can get the pulleys in line, and have the space to install the SC itself, but is it worth the trouble for the gains (not really)

speedyxjs - 26/5/08 at 12:21 PM

quote:
Originally posted by mr henderson
consider turbochaging the zetec


Thats just caused a laugh in the office

mr henderson - 26/5/08 at 12:25 PM

quote:
Originally posted by speedyxjs
quote:
Originally posted by mr henderson
consider turbochaging the zetec


Thats just caused a laugh in the office


Why?

C10CoryM - 26/5/08 at 02:03 PM

I'll vote for a centrifugal blower anyday.
Turbos do not react well in a cornering car IMO. Say you are at steady state cornering where any more accelleration will lose traction. The turbo will often keep spooling up and making more power even though you are not increasing throttle. Means you have to lift, or use less throttle initially. Either way slows you down.
A centrifugal blower just feels like a larger engine.
The only time I would run turbos is if I couldn't fit a blower in the engine bay. Guys with newer camaros can buy turbo kits that go where the muffler is. One benefit is no heat and no intercooler req'd
Cheers.

PS: having said that, my car is a twin screw blower. Not a centrifugal. Just what I ended up with

NeilP - 26/5/08 at 02:14 PM

^^^^ What he said - centrifugal blower if you can afford it - Sound astonishing and can be done without rebuilding the engine if you keep the boost low...

mr henderson - 26/5/08 at 03:16 PM

I guess it all comes down to what one wants from a car, serious power increase, turbo, moderate power increase, supercharger.

BTW blowers may not need an intercooler but compressing air always makes it hotter, therefore less dense, and the fuel air mix more prone to detonation.

[Edited on 26/5/08 by mr henderson]

turbodisplay - 26/5/08 at 04:11 PM

Re turbos in mid corner.
I think a well setup system that limts boost according to RPM AND THROTTLE, will give good performance.
That said, as a turbo is not rpm controlled like a supercharger, it will never be perfect.
Another possibility is traction control, as that will cut power if the increase in boost pressure causes a wheel to slip.
Darren

Ivan - 26/5/08 at 04:13 PM

quote:
Originally posted by C10CoryM
I'll vote for a centrifugal blower anyday.
Turbos do not react well in a cornering car IMO. Say you are at steady state cornering where any more accelleration will lose traction. The turbo will often keep spooling up and making more power even though you are not increasing throttle. Means you have to lift, or use less throttle initially. Either way slows you down.
A centrifugal blower just feels like a larger engine.
The only time I would run turbos is if I couldn't fit a blower in the engine bay. Guys with newer camaros can buy turbo kits that go where the muffler is. One benefit is no heat and no intercooler req'd
Cheers.

PS: having said that, my car is a twin screw blower. Not a centrifugal. Just what I ended up with


I don't agree with this at all - the only time you will have these sorts of problems from a turbo car is if the turbo sizing is wrong and/or boost pressures rediculous. In that case turbo lag and sudden torque increases become a problem when cornering, whereas a well designed turbo system will give you a flat torgue curve from just over 2000RPM to any revs you choose to take your motor to.

Turbo's are great - just get the design right.

Having said that, for a V engine there's a lot to be said for supercharging especialy as you don't then need 2 turbo's.

C10CoryM - 27/5/08 at 03:09 AM

quote:
Originally posted by Ivan

I don't agree with this at all - the only time you will have these sorts of problems from a turbo car is if the turbo sizing is wrong and/or boost pressures rediculous. In that case turbo lag and sudden torque increases become a problem when cornering, whereas a well designed turbo system will give you a flat torgue curve from just over 2000RPM to any revs you choose to take your motor to.

Turbo's are great - just get the design right.

Having said that, for a V engine there's a lot to be said for supercharging especialy as you don't then need 2 turbo's.


Ive driven totally stock, well matched turbo cars to savage uncontrollable beasts and I have yet to find one that does not force you to lift in steady state corners.

Unless I'm building a dyno-queen (dunno if you guys use that term there? Cars that make huge power on the dynometer but run slow times at the track. Hence the joke: What's the difference between a 300hp supra and a 800hp supra? Nothing, they both run 13s in the 1/4 mile ), I will always opt for a blower. If you have a smaller displacement engine, a twin screw will give you the low end torque you so desperately need. If you have a larger disp engine with good torque a centrifugal will give you nice, smooth power on the mid to top end. Just feels like a larger disp engine. Perfect for V8s

Mine is a twin screw on a buick 3800. With 275ft/lbs of torque stock and a ridiculously flat torque curve it should be a real neck snapper. I'd trade it for a centrifugal blower and an intercooler in a heartbeat though.
Cheers.

MikeRJ - 27/5/08 at 07:35 AM

quote:
Originally posted by Ivan
I don't agree with this at all - the only time you will have these sorts of problems from a turbo car is if the turbo sizing is wrong and/or boost pressures rediculous. In that case turbo lag and sudden torque increases become a problem when cornering, whereas a well designed turbo system will give you a flat torgue curve from just over 2000RPM to any revs you choose to take your motor to.


The issue is not the flatness of the torque curve, but the response of the turbo to varying throttle. Since the turbo is connected to the engine only via compressible exhaust gasses, and the whole system is a positive feedback loop, it's inevitable that throttle repose will not be linear as it would with a (positive displacement) supercharger. I love the power delivery of turbocharged (petrol) engines, but Cory's points are certainly valid.

I can remember going to an MR2 owners club track day, and the normally aspirated cars were actually quicker through twisty sections of circuit than the turbos, despite having 70 bhp less simply because they were so much easier to control on the limit.

[Edited on 27/5/08 by MikeRJ]

Ivan - 27/5/08 at 11:49 AM

I guess that the two turbo cars that I have driven for some 320000 kms were strange because they never gave me that problem - maybe I'm just too bad a driver to notice - or maybe I'm just too good a driver and just compensate subconsciously.

Must admit - the one was a homologation special so handled pretty well once some of the negative camber was taken out of the rear (Opel tS) - the other a grandpa car with poor handling but great motor (Volvo T4)

The only problem I experienced on track was that if you entered a corner in too low a gear you couldn't change up because the limited slip diff (fwd) would unlock and the car would go from neutral - or even slight oversteer - to major understeer right off the track - and that had nothing to do with the turbo but everything to do with the LSD unit in my car.

I suspect that people who have problems with turbo cars haven't made the transition to driving them properly and need to remember that the throttle response on a turbo car is different and drive accordingly. I believe that there will be very little difference between the ultimate cornering speeds of two identical cars - one with turbo and one with supercharger.

Also - I don't understand the problem at steady state - unless you have boost creep - which is also a design problem - as it doesn't happen on the straight when your'e cruising - I have never found myself having to come off the throttle because the car is going faster and faster.

[Edited on 27/5/08 by Ivan]

MikeRJ - 27/5/08 at 05:40 PM

quote:
Originally posted by Ivan
I believe that there will be very little difference between the ultimate cornering speeds of two identical cars - one with turbo and one with supercharger.


Given a skilled driver, perhaps not. I'm certain a less experienced driver would certainly find a normally aspirated or supercharged car easier to control on the limit. Turbo lag on a standard single turbo installation is an inevitability, it's the nature of the system and all you can do is reduce it as much as possible through good design and implementation.

When you are cornering at the limit and you need to make subtle adjustments to the throttle, that lag makes things more difficult. It amplifies the throttle settings; you back off slightly and the engine gets less air, and then the turbo slows down so the engine gets even less air etc. Then you put you foot down and nothing happens for some period and then the reverse occurs.

Low pressure turbocharged engines are certainly less affected by this and feel more like a bigger engine, but anything designed for performance with a manual throttle (rather than fly by wire) is going to suffer from this to some extent.

grazzledazzle - 28/5/08 at 07:54 PM

Hmmm. Bit of thinking to do here then.
Maybe cams and throttle bodies will do it then.

Ivan - 29/5/08 at 12:10 PM

quote:
Originally posted by MikeRJ
Given a skilled driver, perhaps not. I'm certain a less experienced driver would certainly find a normally aspirated or supercharged car easier to control on the limit.

I agree 100% - but for those fractions of a second in the corners why miss out on that wonderfull surge of power that only a good turbo motor can give down the straights, although a supercharged motor comes close.

Simon - 29/5/08 at 07:38 PM

Do I need to say what I prefer

ATB

Simon

Ivan - 30/5/08 at 07:47 AM

^^^