Twin scroll turbo flange.

[tauruck]

Guys, I've got twin scroll turbos and a local "expert" suggested I build headers
with a divider to match the split flange.
Is this really necessary for LSR?.

[Dynoroom]

No.

[tauruck]

That's the best answer ever on the site.

Short and sweet.

Thanks Mike.

[maj]

Wouldnt that depend on a few things rather than just no ?

 Like extremely large turbo (turbos) and tall gearing may need the full use of split pulse

[kiwi belly tank]

The answer is still no.
  Sid.

[maj]

Just let them wind up then 

[Sumner]

Wouldn't that depend on a few things rather than just no ?

I'll take the track that in a few instances it is worth at least looking into.  The 3 liter I'm looking into building with the turbo that I can afford and build the HP I"d like (notice some of the preceding had conditions) I feel would benefit from a twin scroll with a divided exhaust and so do some of the Borg Warner techs that I've gotten advice from.

It comes down to the problem that after a gear change (remember this is in my situation) the rpm's drop enough that the little engine is not making enough exhaust energy to then power the turbine back up again (or at least not very quickly).  

From Borg Warner's Matchbot program on sizing some of their turbos ...



Notice that in a situation like what I might be running into I might get a 10%-15% efficiency boost at my lower rpm point.  So in my case I'll try it since I'll need all the help I can get with the large turbo on the little motor.  If you have the money to spend then of course there are better combinations (turbine/compressor matchings) where this might not be useful at all or needed.

With the same turbo(s) on Hooley's engine they did not recommend it at all.  So in 90% or more of the cases for what we are doing I'd agree with the others on not worth the effort,

Sumner

[Dynoroom]

In other applications a divided housing MAY be an advantage, but he asked about HIS project. The answer is NO.

If we want to discuss the merits of divided vs. open turbine housings, Headers vs. log exhaust, efi vs. carb., high vs. low compression ratios, by all means lets start a new thread.        

[Sumner]

In other applications a divided housing MAY be an advantage, but he asked about HIS project. The answer is NO.

If we want to discuss the merits of divided vs. open turbine housings, Headers vs. log exhaust, efi vs. carb., high vs. low compression ratios, by all means lets start a new thread.        

Sorry but Maj asked about different situations, at least I though he did.  Delete my post if you want,

Sumner

[Dynoroom]

Don't get your feelings hurt Sum, lets just start a new thread. The bike guys will have even other points of view. 

[wheelrdealer]

See Mike:

You got excited and thought you were hearing a Yes or No answer... but more times than not in our world its a world of maybes and nuances!

BR

[tauruck]

It's all good Bill. No problem on all the answers.

Over here the turbo guys are mostly into street driven
FWD "toy cars" or drag racing. Their needs differ.

No experts on LSR so when the youngster suggested
building a fancy exhaust flange on an already complicated
set up I needed to just make sure.

I have a guy that will be doing all the turbo stuff.
I trust him and he said not to worry about the split exhaust.

I come from a Holley carb era and the turbo thing is new territory.
Apparently we'll be replacing the turbine wheels because the factory
items aren't suitable for our application.

One thing that you can count on is that you'll get good advice here
on the forum.
Thanks all. Have at it. I appreciate every opinion.