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Twin Turbo? 2 new Ko3`s...

These are not mine,possibly selling for a friend who upgraded his Audi S4.These turbos look new and they have only 4000 miles on them,he replaced them with Ko4`s right after the first service! l was thinking of selling my 3.2 turbo system and going twin but l`m testing the waters here first,any thoughts on these units?
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Old 11-02-2007, 11:45 AM
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Too tiny hotsides. Even the Ko3S model turbochargers, which are a ko3turbine/ko4 compressor are realistically too small for something of this nature.

They'd spool like mad on your motor, but would choke out really quick. If you ever get a chance to take apart a Ko3, you'd see that the turbine is about 1.3" in diameter. Compare that to the likes of a single K27 or such Heck even a single Ko3 chokes out right quick on a 1.8T VW/Audi
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Old 11-02-2007, 01:28 PM
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I don't see why this is so far off if responsiveness is the goal. 1 Ko3 for a multivalved 1.8l or 2 Ko3's for 3.3l 2 valve heads. If they push 250hp out of one, then 450 or so out of two should be douable, no? I realize our aircooled engines don't respond as favorable as a 4/5 valve head water cooled, but they don't flow as much either.

I'm not saying Adam is wrong nor I'm right. Just a little devils......
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Old 11-02-2007, 08:37 PM
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What kind of boost pressure would you have to run to get that kind of H.P. ? That might be a problem on a 3.3 engine
Old 11-03-2007, 03:22 AM
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Quote:
Originally Posted by 964 T #304 View Post
What kind of boost pressure would you have to run to get that kind of H.P. ? That might be a problem on a 3.3 engine

That is the problem with these K03's...they're so small that you need to overspeed the turbos to get any decent flow, which results in alot of hot air off the compressor. If he's planning an building the setup and running feeble boost then they'd probably fit the bill..........I've yet to meet a Porsche owner who tweaks they're car and doesn't want more power

Ko3S cars are crank rated at about 220hp at 15psi, standard ko3 around 180 at 15psi. That's with the VE and head setup of the modern 20valve heads on the 1.8T I just personally think if he wants to do this to go for a set of Ko4's(it's why the S4 guys do it). You'd have a cooler charge temp at lower boost pressures(better for motor) and have more useable turbo/rpm range as well.
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Old 11-03-2007, 04:36 AM
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l like the T04,60-1 l`m running on my 3.2 but l think these would be fine for an SC that wanted to run up to 10 lbs boost on stock compression.Bigger isn`t always better unless we`re talking garage space
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Old 11-03-2007, 08:58 AM
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K-03s = choked Porsche motor of any displacement.
Ok maybe on a four cylinder...
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Old 11-03-2007, 10:17 AM
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You're right bigger isn't always better. But too small is just as bad in many ways as well. Hey feel free to try it out, but I'm telling you they're too small. They choke out in stock format on a super efficient 2.7L as it is anyway....

Here's the c-map for a ko32072 from an S4



It's the turbine you have to watch out for

Here's a Ko42075, what's on that upgraded S more than likely




Those "xxxK" markings on the maps are rotating assembly RPM speeds at that given flow, IE 175K is 175,000RPM.......overspeeding = yes....your typical K27 hits the 100-110K mark at full(stock ~.8bar) boost on your typical 930/965.
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Last edited by BoxxerSix; 11-03-2007 at 01:22 PM..
Old 11-03-2007, 12:03 PM
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Here is a K27 map thanks to Goran.



1 KG/sec = 132 lbs/min

So, 0.2 is approx 26.4 lbs/min

GT35 map also thanks to Goran
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Old 11-03-2007, 01:03 PM
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K27 map converted to lbs/min



I have K26/24/16/14/etc. Also have weird KKK/BW stuff from cars like the Audi RS2. Anytime I find a new map I save it for reference at a later date. Rebuilding turbos I have people ask me for this stuff all the time so you get used to saving things like this
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Last edited by BoxxerSix; 11-03-2007 at 01:19 PM..
Old 11-03-2007, 01:17 PM
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Adam,

Since we have your attention and obviously you have a knowledge base, what would you like in a responsive GT garret setup in TT format on a 3.3/3.2?
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Old 11-03-2007, 03:30 PM
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Quote:
Originally Posted by Lukesportsman View Post
Adam,

Since we have your attention and obviously you have a knowledge base, what would you like in a responsive GT garret setup in TT format on a 3.3/3.2?
I wish I was in an area where I had more Porsche customers. You guys are fun to chat/work with This is hard to answer, not in the physics of it, but rather how biased I am towards responsiveness and of course the numerous variables that go into such a setup. Personally, I'd rather run slightly larger turbochargers(compressor wheels) at lower PR's to get the same flow rate as smaller wheels at large PR's. The trade off is a lower charge temp for more lag, but it's good for the motor and longevity vs all out spooling performance.

However set my petpeevs aside and with throttle response in mind and a priority here, for a low level(300-400 crank) build with some great offline performance a biturbo setup using GT2554R's .64a/r would work real nice. You'd get that power at moderate pressure ratios and efficiency. GT2554R is comparable to a well ported K04, yet still flows a bit more, and more efficiently at that. I've personally yet to try the 82 housings in this sort of application, but I haven't had the 64's choke out yet when kept within the compressors' range. 82 would most definitely carry you out well past 6500rpm at the trade off of seeing oh 1-1.2 bar around 3500est. GT2560r's work well in a 420-550 crank range, again .64 a/r turbine for low/midrage. Garrett claims ~325hp from a 2560R, but that's right close to the surge limits of the compressor. The key to using small spools in a twin setup to get power is GOOD intercooling(efficiency and deign).

As a side note, anything above that and you're into 28xxR territory. 2854r's are nice, but once in this family I'd go straight to a 2860r at the least. Keeping in mind though, this is for mid boost(1.2 bar) and response. If it were my car, I'd use the 2871R's, but again I like a little lag. Keeps me on my toes while driving. I'd also use free float housings with external gates where possible to avoid creep/spike issues with the smaller internal gates found on the 25/28 series. This however, is outside the realm of what you're asking so I won't go too far on it.

The GT 25 family is one not utilized much in the performance field as most people are accustomed to the GT2860r or RS in search of big power vs streetability, but they're a perfect turbo for those who are not looking for much more than 500 at moderate boost levels. They can achieve more, but then you're back to overspeeding and cramming hot air at stupid PR's for such small turbos.

I've built a GT25 biturbo setup for a moderately built 3.3 965 engine with TEC3R EFI, 2560r .82 a/r's but it ended up in a sand rail and not the appropriate Turbo chassis(idiot!) I'm currently working on a 3.3L biturbo setup using 2871r's for my own kit car, but it's a subaru EG33 liquid cooled engine from an SVX. Not P-car comparable really so I don't know how well those number will match up to this field here.

I'll take a picture of a Ko3 turbine at my shop on Monday to show you how small they really are. I'll post it next to a 2860R turbine for comparison..
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Old 11-03-2007, 05:49 PM
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I say twin 30Rs would be sweet. On a boxxer motor, boost too early mean beaten rod and crank bearings as the motors are already beating themselfs apart at 180 degrees.
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Old 11-04-2007, 08:33 PM
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Quote:
Originally Posted by 930gt-40r View Post
I say twin 30Rs would be sweet. On a boxxer motor, boost too early mean beaten rod and crank bearings as the motors are already beating themselfs apart at 180 degrees.
There's more than a few 996 turbo guys doing just that....twin 3071r's
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Old 11-05-2007, 03:27 AM
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Hell, I know of one Proto car running twin 35s with GT-3 cams running to 8200 rpm.
Can we say top end? I would dream about this setup if I didnt have to change my sheets every time.
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Old 11-05-2007, 03:19 PM
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Adam,

No, you certainly didn't go "long" on your answer. That was great info and interesting input/opinions. Your opinions with your reasons behind them were very useful past just objective reading in books. I had earlier arranged a setup for a 8:1 3.0 using GT2054's using Webcam's 20/21 and EFI. Now that I'm going 3.3 with traditional 7:1 compression and higher boosts should I even try the GT20's or go ahead and figure on new GT28's. The GT2054's I have use proprietary flanges I've converted to Vbands, so they can't be easy swaps at a later point to a larger chassis.

The GT20's were listed as 260hp and when I used the maps for a 3.0 at .8bar it looked to be in the sweet spot on the graph for a responsive 400hp engine. Is this all just a wash with the engine spec changes? Am I even evaluating the maps correctly for our air cooled 2 valve hemi engines?

Sincerely appreciate your time,
Luke
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Old 11-05-2007, 06:25 PM
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Gt20's at 400hp on a 3.3L might be just a tad of a stretch. Consider the Gt22's if you're going to stay right around that 400 mark, just ever so slightly bigger. Gives you just a little more room. Even that might be tight on a 3.3. You're reading the maps correctly, probably just stretching the limits more than I would. Give me a day or so to finish up these cars here and I'll sit down and run a few maps myself for you and see what we come up with on those GT20's/22's. It's getting real cold here and I've got to finish up these few cars sitting outside my garage as the ones inside are all on standby waiting for parts to arrive

Man that must have been a snappy little motor at 8:1 with those little GT20's I built a little 2.0L I4 back in the day for a with twin 22's and that motor revved like a son of a ***** no matter where you were in the rev range. Can't imagine 20's!!!

I think it's be a fun project to build one of Henry's little 2.8L's with a little bit of compression(oh 9.0:1 maybe) and some good ignition control(standalone) with dinky turbos. Not huge HP, but something really fun to drive. Make a motor that revs out to wits ends with a little boost behind it!


Quote:
Originally Posted by Lukesportsman View Post
Adam,

No, you certainly didn't go "long" on your answer. That was great info and interesting input/opinions. Your opinions with your reasons behind them were very useful past just objective reading in books. I had earlier arranged a setup for a 8:1 3.0 using GT2054's using Webcam's 20/21 and EFI. Now that I'm going 3.3 with traditional 7:1 compression and higher boosts should I even try the GT20's or go ahead and figure on new GT28's. The GT2054's I have use proprietary flanges I've converted to Vbands, so they can't be easy swaps at a later point to a larger chassis.

The GT20's were listed as 260hp and when I used the maps for a 3.0 at .8bar it looked to be in the sweet spot on the graph for a responsive 400hp engine. Is this all just a wash with the engine spec changes? Am I even evaluating the maps correctly for our air cooled 2 valve hemi engines?

Sincerely appreciate your time,
Luke
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Old 11-07-2007, 08:37 AM
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