That is why you get something called a 2 step with that stall speed on the turbo. Your car sits at 4.5rpms spooling and spools instantly sortive like brake boosting. So you can insta spool with a giant turbo

 

I have been stomped by a 410whp EVO and a 400WHP honda. They were both single turbos and trust me they spooled up quicker. yes they had pretty big turbos ;P

 

WTF are you talking about??? 2 steps? 2 step has nothing to do with the turbos at all. It is just a launch control to pull consistent 1/4 mile trap time. As for comparing EVOs and Hondas to Audis, they typically run garret turbos. Most likely GT28 or 30. These are far better turbos than K03s and K04s. Their compressors are larger than K04 but turbine size is smaller and their compressor map is way different. Not only that 4 bangers wind to 8500 rpm easy, while your 2.7T wind to 6500. And your car weighs literally a ton more than the EVOs. Of course your car will be whipped.

 

haha no **** I was going to get whipped... the honda was 1800lbs with drag slicks with a giant GT. The evo was full stage3+ cams ect. I still believe a single turbo can produce just as much if not more power and better times than twin turbos.

 

I am no expert but this is incorrect, quite the opposite as a matter fact and why Audi chose this setup (less turbo lag, build high TQ sooner).
We have 2 smaller turbos, for quicker sppoling... but they'll produce less boost and power, max out earlier than the one big turbo.
Also, one turbos does not feed the other... not in sequence, they work in parallel.

 

if thats the case Hxgaser, that single boost kick in at a letter time 4k+, then one would expect that the bi should have an enourmous advantage due to the fact that, they kick in earlier and sopposingly generate and sustain alot more power and torgue down the road.Going through this forums , this is the second time someone has brought up this question of bi turbos perfoming less than expected in competition with presumable a lesser car. i am ignorant in this sector but i do have a lot of interest and i am learning alot as well

 

You are right, that small turbos spool quicker. (BTW 4K+ is a hypothetical number) But the issue is that small turbos generate lower boost. So the amount of air going through is a lot more with larger turbos in general. Bi-turbos in 2.7T are not designed for high boost numbers from the factory. They perform well all around town, but not really designed for all out racing. Also, 2.7 turbos are not sequential.

A typical sequential turbos have one small turbo feeding directly into the larger turbo. What this accomplishes is that small turbo builds boost quick which allows the larger turbo to spool faster. So you get the best of both world where you have boost through out all engine speed, and have more boost at higher rpm. But in most cases, these setups are not easy to control Dealing with boost buildup, timing, and proper sizing of the turbos are not an easy task.

 

wow, you are good. your answer is complete thanx

 

Just read this post, good for a laugh. HX you nailed it, very complete answer. I would still love to see what a big Gt35/40 single turbo set-up was capable of on the 2.7t motor. Hopefully one day someone (with a streetable car) will show us this set=up. Until then I will stick with my little K04's

 

ignorant, nothing77 i think so. Hope you die in your low paying job. Thanks again for bringing nothing to a topic.Def a great answer though haha All of them have been pretty good posts. I still don't find the spool time on the ko4's quicker than the ko3s to be honest. Even putting ko4's spool time vs a 35r I believe they would be really close. The only difference your telling me is the boost when they do spool. Making the (higher boosting single turbo) pull you all the way through mid gear and topend. Ohh and I did not know that about our turbos that one doesn't feed the other. I always thought the drivers side feeds the passanger side. Thanks for the information again. Look at a 1995-1999 bmw m3 turbo kit (600-650chp).. the bmw runs a 3.0-3.2 I believe.