two turbos into one TB?
Thread Starter
AudiWorld Member
Joined: Jul 2009
Posts: 163
Likes: 0
two turbos into one TB?
does this design ever cause an issue with one charge side flowing into the other where they meet or do they just flow perfectly due to negative pressure from the engine (not being any sort of issue at all)
just a thought
just a thought
AudiWorld Super User
Joined: Jul 2005
Posts: 2,042
Likes: 4
It just forces the pressure to be equal in both halves. The flow will not be equal abut the pressure at the TBB will be. All of the pressure drop from the piping/intercoolers aids with equalizing pressure at the turbos.
AudiWorld Super User
Joined: Jul 2005
Posts: 2,042
Likes: 4
Now that I'm off work I can go into more detail. Unfortunatly I have to convert things into electrical analogs to explain it (in my head) so it doesn't really help others much.
Here is the theory to twin parallel turbos. (IMO)
The intake manifold pressure will be equal for both banks. On average the mass of the air forced into each cylinder will be the same. The amount of fuel sprayed in (assuming matched fuel injectors) is equal for each cylinder. Therefore the amount of both air and fuel in each bank is approximatly equal.
Now we make the assumption that the turbos are well matched. Maybe within 5% of each other (my guess). The amount of exhaust gases between the banks will be equal, as per above, so the turbos should be very close in output to each other. (A side note is that the wastegates are both fed from the same source and must be very closly matched.)
There will be some differance between flow of the turbos, however they both find thier equalibrium points. This might mean that the one turbo will push slightly more air at a given pressure level. Another thing to take into account is the large volume of air that the innercoolers hold. This also acts as a way to equalize the flows accross each bank.
My explanation isn't as good as I would have hoped. But if you conver everything to electronic analogs it makes perfect sense.. lol
Here is the theory to twin parallel turbos. (IMO)
The intake manifold pressure will be equal for both banks. On average the mass of the air forced into each cylinder will be the same. The amount of fuel sprayed in (assuming matched fuel injectors) is equal for each cylinder. Therefore the amount of both air and fuel in each bank is approximatly equal.
Now we make the assumption that the turbos are well matched. Maybe within 5% of each other (my guess). The amount of exhaust gases between the banks will be equal, as per above, so the turbos should be very close in output to each other. (A side note is that the wastegates are both fed from the same source and must be very closly matched.)
There will be some differance between flow of the turbos, however they both find thier equalibrium points. This might mean that the one turbo will push slightly more air at a given pressure level. Another thing to take into account is the large volume of air that the innercoolers hold. This also acts as a way to equalize the flows accross each bank.
My explanation isn't as good as I would have hoped. But if you conver everything to electronic analogs it makes perfect sense.. lol
AudiWorld Senior Member
Joined: Sep 2006
Posts: 1,184
Likes: 1
Putting a big turbo in the mix causes more lag. Two smallish turbos do just fine. The guys who put in bigger turbos often end up upping their rev limits to the top of redline ($$$$) so they can take advantage of that top end power and make up for the lag time spent in the lower rpms.
Trending Topics
AudiWorld Super User
Joined: Jul 2005
Posts: 2,042
Likes: 4
And, the exhaust manifold routing of a single turbo design on a V6 car make it near impossible. Audi would have had to design a new engine to make it work. (or waited for the VR6)
Now with FSI you can have the intake maifolds on the exterior of the engine and a single exhaust manifold between the V. This allows for a single turbo much easier.
Now with FSI you can have the intake maifolds on the exterior of the engine and a single exhaust manifold between the V. This allows for a single turbo much easier.
AudiWorld Stories
Bringing Audi to Life for Audi Fans
10 Strangest Audi Designs That Actually Made Production
Joe Kucinski
2027 Audi Q7 and SQ7: Audi Upgraded EVERYTHING!
Michael S. Palmer
Audi Unveils Absurdly Cool New Supercar: 10 Things You Need to Know!
Verdad Gallardo
The Highs & Lows of Every Audi C-Class Generation
Joe Kucinski
Top 10 Most Expensive Audis Ever Sold on Bring-A-Trailer
Brett Foote
10 Audi Features & Options We Miss the Most!
Joe Kucinski
Audi Recreates Crazy-Looking Speed Record Breaker From 1935
Verdad Gallardo
Coachbuilder Recreates the 1995 Audi TTS Concept
Verdad Gallardo
Every Audi V10 Car Ranked!
Joe Kucinski
AudiWorld Member
Joined: Jan 2010
Posts: 360
Likes: 0
From: houston