same here.. my wife drives a s6 avant.. but the 230 hp is not fast enough for her and the kids.. she test drove a 420hp rs2, and liked it more.. that's why i'm rebuilding it.. ( that what you get when you put your wife in small fast cars in the beginning of your relation 12 years ago, and during the relation just continue with letting the misses drive fast cars)
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So, has anyone used a holset that spools before 4000 rpm?
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Prj,
stick to your guns in your quest / search, I want the same as you, less than 350bhp, but with as early a spool up as possible, i.e. better than standard if possible.
S2 is big for the city, but I still wouldn't drive anything else.
Multiple cars is not an option for me either. Also one is never in the right car at the right time. More fun to drive the "weekend car" seven days a week.
Not every S2 driver wants to drag race on a strip or top out on motorways.
Looking forward to the rest of this thread, what about more info or experiences of the CT355 or the next smaller CT turbo, CT???
Any links to retailer or manufacturer type info on CT turbos that non engineers types can understand ?
Thanks.Comment
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having read all the above, i can tell you that the 3071R 0.63AR that i had previously did not give me any surge(and if it did was negligable on perhaps 6th gear when going WOT from 2000rpm), and with VEMS and a fairly aggressive throttle responce i had the impression that there was very acceptable lag there.
My best 3d gear run recorded a 620Nm of torque @ 3900rpm with 2.1bar. However, 4th gear was coming up well within the 3200-3300range and the car was really flying within the midrange rpms. From graphs i have the power goes down pretty fast after 5500-6000rpm, but im guessing that is something you wouldnt care.
I presume that the 3071 with the 0.63AR is faster spooling than the good old K24 7200, it will surge, but negligable with the correct map. Having said that, with VEMS i saw a tremendous difference in spooling than what i had with motronic for some reason.It looked as if the N75 boost control from the motronic was very poor.
With that in mind, i could make an assumption that getting a small turbo from any manufacturer (Precision, CT, Garrett, KKK) and journal rather than BB, may be the only solution to avoid surge, and still be able to achieve low rev spool.Comment
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It's still slower spooling than the K24-7000... I think that turbo is too big really.
Motronic only requests full boost if TPS is 100%. Meaning fast, pedal to the metal.Having said that, with VEMS i saw a tremendous difference in spooling than what i had with motronic for some reason.It looked as if the N75 boost control from the motronic was very poor.
If in vems the boost map does not take the TPS into account, then it will always seem quicker, because you will get lots of boost when part throttle. You can map motronic to always request maximum boost, not depending on throttle position, but that's useless.
That's why I am looking for a holset turboWith that in mind, i could make an assumption that getting a small turbo from any manufacturer (Precision, CT, Garrett, KKK) and journal rather than BB, may be the only solution to avoid surge, and still be able to achieve low rev spool.
Regarding CT turbos - there are no compressor maps for them, which makes sizing quite difficult.Comment
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yes, that is their ... 'secret'! which i think it is just a marketing thing.
recently they used a CT turbo on a 1.8T engine in greece, which a very small AR to get very good spool and managed to get it to 1.4bar (because of stock internals) and a spool of 0.4bar in 400rpm( 1bar @ 4000rpm and 1.4bar @ 4400rpm), and i think that is quite bad for a 3BB turbo. Then again they are claiming of some kind of bearing damage due to some oiling issues, which could be true. but with an AR of 0.4X full boost after 4000rpm seems a lot to me.(for a 1.8T engine).
Bram has experience on CT turbos among other in hereComment
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I think CT is just way too expensive for being (mostly) a Garrett copy.
Rather buy a Garrett turbo then, at least the sizing is easy because the compressor maps are widely available.
Still though, I'd really like a small holset. They are like 2x cheaper and not worse.
Perhaps the HE221 would be of interest for me?Comment
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Have You seen lot of Holset maps around, then?
CT is not a Garrett copy, they use mostly Garrett comp wheels. Sizing a custom turbo like CT or Presicion is actually easier than Garrett ones, as there are multiple turbine choises for each compressor.
CT has had lot of issues lately with poor turbine matching to the turbine wheel. I have had my share. When things are right, they rock pretty good, I've had my share of those as well.
HX40 super is a stunning turbo for I5, best we got from my friend's car was 662hp/775Nm from 2.2l I5 with it. Engine was pretty far from stock, though.
I am not with any of the hybrid Holset suggestions people have stated in this thread. If You plan to use Holset, stick the the lineup turbine-compressor wheel combinations, and play with the housing selection. Just stay away from HY35, which doesn't fit anything else but the compressor / generator where it belongs to. He221W with billett comp wheel seems to be pretty good as well, haven't seen any of those on I5's though...Everything less than 2 bar is considered to be naturally aspiratedComment
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There is a certain book which has quite a few holset maps.
The maps do not have efficiency islands, but at least it is possible to see the surge and chokepoints.
But turbo maps are only one thing, it would be really nice if someone could say "BTDT, use this turbo".
I am sure it is, but I'd really like to have about 1.5-1.6 bar of boost, and around 1.3 bar by 3000-3100 rpm. I really don't need a drag queen or HP monster where nothing happens until 4500-5000 rpm, I'm quite happy even with my chipped S6, 280-320hp is fine. Anything that can spin my wheels in first gear without doing a hard launch is overkill for me.HX40 super is a stunning turbo for I5, best we got from my friend's car was 662hp/775Nm from 2.2l I5 with it. Engine was pretty far from stock, though.
Thank youI am not with any of the hybrid Holset suggestions people have stated in this thread. If You plan to use Holset, stick the the lineup turbine-compressor wheel combinations, and play with the housing selection. Just stay away from HY35, which doesn't fit anything else but the compressor / generator where it belongs to. He221W with billett comp wheel seems to be pretty good as well, haven't seen any of those on I5's though...
I doubt many people have tried a small turbo on the engine. Everyone seems to retrofit RS2 parts under the bonnet.
If I will have no luck, then I will just get a RS2 replica manifold and get my turbo rebuilt, but I am also thinking of the HE221W...
Some stubborn part of me refuses to believe that there isn't anything better than a K24 7000 that fits my needs and is not obscenely expensive.
That GT2871R you were/are selling seems tempting, but I think it is too big for me + surging problems.Last edited by prj; 2 July 2010, 22:11.Comment
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OK, so You are one of those guys. I am not taking part to this discussion anymore.
My last advice, then end of discussion: swap to 2.7T.
Oh, wait a minute, it is not good, as it does not make 1.6 bar with stock turbos... And huh, neither does an RS6 V8. How silly of me. Yea, better stick with a turbo no one has tried before, then.Last edited by repo; 2 July 2010, 22:47.Everything less than 2 bar is considered to be naturally aspiratedComment
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guys , maybe the best choice for you can be some EATON and you can get 0.5 bar form 1200rpm-7000rpm.
nobody try this before...
my advice is ... newer try something new.. go on trusted combination.. something new will do people with more money.Comment
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no eatons.. people who tuned with g60 now eatons are garbage..
shame a 2.2 is to much for a g60, cos the eff. of a g60 is suberp.
a guy i know has a 1.8 20v turbo with a g60 and a gt35r.
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