So for my 1.9TD, what would be the best turbo for max performance.
That is way to vauge a question to possibly answer, that and it has been attemped to be answered in at least 11ty billion threads just this week...
Let's keep it on track to compounds, or sequentials as some people would like us to call them... (You know who you are
)
As has been covered in a few threads recently, there is a big difference between 35psi from a T3 or kkk24, which both are at max at about 24psi, according to there maps and a GT25R or sequential turbo's running 35psi.
Something else to keep in mind, twins are NOT plug and play you need to tune them. This means you will need at least an EGT gauge and
3 boost gauges. "Low pressure, Manifold pressures, and Drive pressure"
Now to even get a decent start at sizing turbo's you need to get the maps for both the turbo's you intened to run, and then lay them one over the other so that the airflow and pressures are on the same scale, and then you need two that fit well together. I am No engineer, nor do I claim to be an expert at turbo matching, but from my limited knowledge you want to find two maps that make one nice big map without any gaps, and with some overlap but not a tone. (how is that for a vague discription) Once you have seen a couple maps for well designed sequential turbo's it will be easy enough to spot what you need, but there in lies the problem the few people that have that knowledge tend not to share it. :wink:
I'm hoping that one of our resident engineers will chime in here with a more technical discription of sizing sequential turbos... cough, cough TDIMIESTER, QuickTD...
A good place to start for sizing the high pressure turbo is the stock turbo. Now in this case we have a couple to choose from, in bvanetten's case the k24 or T3 is obviously to big, as he is haveing problem's with spooling it all on its own in his application. Here is my very general list for high pressure turbo's and there app's:
T2/K14/k03 - really borderline to small for everything as they will create pretty huge drive pressures, an external wastegate version might do better depending on manifold design.
k14/k24 - hybrid probably the smallest I would consider running ironicly most people when making hybrids like this use the big cold side with the small hot side, but for this it would be the opposite to keep the quick spool, but with liveable drivepressures. This would be my backup recomendation for bvanetten for the highpressure turbo
GT15 - found on early TDI's before the intrduction of VNT turbo's, it spools great and has better flow then the above mentioned turbo's. This would be my recomendation for a street / 4wd application.
K24/T3 - Decent hot street turbo, still a little slow spooling compared to the GT15 and a little less flow, but cheap and availble stock on every car. Too big for 4WD app, but decent for a cheap turbo with good fueling.
T3 .48 hotside - app Merc300TD - good flow and decent spool, on a big fueled street / strip car. Also makes for a good sinlge turbo for someone looking for reduced egt's on a turned up pump.
GT20 - Quicker spooling then the K24/T3's and more flow, best alround street / strip turbo, great single turbo and great for building upon. Only draw back $$$$ both for the turbo and for a new exhaust manifold.
GT22 - Borderline big as a street turbo as a single, and broken crank big as a hp turbo (ie, no one in known history has made enough power to use this in a compound setup)
Well as I said earlier I'm no expert but this is my "guess" on how things work :roll:
As for the low pressure turbo well that will be another installment... Another time...
But for a quick preview in no perticuler order:
-HX30
-K26
-K24/K26 hybrid
-GT22
-GT25R
A couple more things to keep in mind is that sizing turbo's is a bit of a black art and there are very few people who are experts at doing it. The best way is to find one of them and bribe them well, short of that it is trial and error. A very important thing to remember is that not all turbo's are created equal there are at least 7 variations of GT20's sold by garret, not all will work well on our motor's. That is just Garrett there are a ton of companies that start with a garrett frame and build hybrids out of anygiven turbo. Giving you hundreds of choices of sizes within sizes. Also there are a number of other turbo companies out there that I don't have much for personal experiance with and as such I did not touch on, this is not becuase they are poor turbo's it is just because I don't have any personal experiance with them. Just to name a few: Switzer, Mitsubishi, Catapiller, Holeset, ect...
Well hopefully this sparks a bit of conversation.
Topic: Compound Turbos (Read 8003 times)
