Author Topic: turbo advice?  (Read 1481 times)

Offline vee-dub90

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turbo advice?
« on: January 18, 2013, 04:25:16 pm »
just having a browse on turbo dynamics and they do a few hybrid ko3 turbo's

such as: http://www.turbodynamics.co.uk/shop/md178-stage-2-hybrid-turbo-for-vag-18t-150bhp-engines-p-2670.html

and: http://www.turbodynamics.co.uk/shop/md417-stage-3-hybrid-turbo-for-vag-18t-150bhp-engines-p-2727.html

reckon they could be any good with the rothe manifold and downpipe?

also would 310cc injectors be too small or should i go for bigger ones?

im thinking of aftermarket management too to get the most out of it..

specs on it would be:
1341 forged rods and pistons
big valve head
268 newman cam (maybe)
vernier pulley
gt inlet
51mm tb
lightened and balanced flywheel
helix clutch
oil squirters
windage tray with baffled sump
rothe manifold and downpipe, may use a custom 3" system
tial dumpvalve
custom fmic
gizzmo or greddy boost controller

any advice?

Offline dub-disaster

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Re: turbo advice?
« Reply #1 on: January 18, 2013, 05:04:47 pm »
For £810 There are much better turbos out there for less money. k04 compresor wheel isn't the most efficient the world. If your going to spend that sort of money id go for a different turbo and a different manifold with better flow than the rothe.

As for the rest of your desired set up. I think you need to think about what you're going to use the car for, what sort of power you want and how you want it delivered and tailor your setup toward that.
 I.e. if you use the car on the road you might want a smaller turbo with better transient response you may choose a cam that spool your turbo earlier for more mid range grunt.

If its mainly a track machine than you can go big and not worry to much about lag the same can be said if you just want big hp numbers for rr days although this may make for an a slower car in real world terms.

If you intend on using the car in both situations then decide where it will spend more time and make a compromise between the two setups biased toward where your car will be used more.

budget will also plan a large part the setup you've listed will probably not leave you Much change from £5-6k if done correctly turbo conversions can have lots of hidden costs.

For best bang for buck and a good all rounded you can beat an overworked k03 good road manners and is still reasonable for odd track day and any other thing you can throw at it.
« Last Edit: January 18, 2013, 05:08:41 pm by dub-disaster »

Offline vee-dub90

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Re: turbo advice?
« Reply #2 on: January 18, 2013, 05:15:16 pm »
I see what you are saying, im not bothered about costs to be honest, as I can get a lot of stuff cheap through work. I have also been thinking about a gt25 or 28, I will only be using the car on the weekends really anyway and maybe an odd trackday

Offline dub-disaster

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Re: turbo advice?
« Reply #3 on: January 18, 2013, 05:25:13 pm »
so you will mainly be using it on the road then. In which case id have think what you're target power is and choose the most efficient turbo that is cable of flowing enough air to make that power and that is the smallest available this means good transient response whilst still obtaining your power goal. don't be to ready with your target and remember out and out power doesn't specifically mean quickest point to point.
All the calculations you need to find the right compressor for you are available in forced induction tuning by A.greyham bell read it before you spend you money as it might save you money in the long run. calculations aren't everything but can point you in the right direction. Then trial and error comes into play.

good luck.


Offline prankstar2003

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Re: turbo advice?
« Reply #4 on: January 24, 2013, 06:26:02 pm »
Has any one swapped out compressor wheels for lighter ones? I saw some billet ally ones for sale the other day. With a lower inertia due to lower mass, this should allow a larger turbo to be run for a given spool time? I'm not sure how that would impact on efficiency, mind. But to a point, bigger must be better if spooling quickly but not at it's upper most limit (where efficiency would drop off). May be an option, but the billet wheels aren't cheap (and may not be available for your chosen turbo).

Offline Andy

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Re: turbo advice?
« Reply #5 on: January 24, 2013, 08:18:53 pm »
I'm not convinced they're worth the extra dosh unless you're going balls-out.

Massively generalising, the size and shape of turbine & compressor wheels and their housings determine the boost threshold - i.e. the point at which you can make full boost. So on a diminutive K03-005 on a 1272cc 8v Polo engine and 268° camshaft the boost threshold is around 3000rpm. Below 3000rpm you can't make your target 15psi of boost, but above this engine speed it's not a problem.

We then lighten the rotating parts, but they're the same size/shape as before. Full boost will still be achieved around 3000rpm, not anything much lower as you've not changed the airflow characteristics to get anything moving differently. However, if you're cruising at 4000rpm and nail it, the lighter turbo will hit you with 15psi of boost more quickly than before. You've always got the airflow for full boost at this speed, but now there's less mass to get spinning up.

The turbo books will explain this more clearly than I have here!