Split Pulse Turbo/Manifolds

[steve murch]

words from OWENS DEVELOPMENTS ENGLAND regarding the twin entry

"a twin scroll turbo is not good for high power outputs because, when you split the ports in the turbo, the wall between the two can distort.
At high speeds and high temps that can to effectively blank off one of the ports.
its a comon problem on subs and mitsi you get one particular port not functioning as it should. casing durability can also be an issue.
particularly on group n evo turbine housings,which are prone to cracking.




go to there site and even email them its interesting stuff if your not up on the play,they charge very hard thus its good for me when the stuff gets sent to me to do, nice stuff to play with.

[Lith]

I have carried on reflecting on this, but something which is still not answered is - how did my mate go from 390kw @ wheels to well over 400kw @ wheels going from a single entry to twin entry T04Z setup if the twin scroll setup is inherantly more restrictive?

Everything else the same, just changing from a twin entry turbo and manifold setup. The manifold was modified as little as possible to go from a single collector to a T4 twin collector.

So far every result I have been privvy to have resulted in more power, torque and spool. One of my mates got a bit of a shock recently by finding he was timing limited in the lower revs going from a single .82a/r to a twin 1.06a/r twin entry GT3582R on his car but then it later occured to him that he was running a good 10psi more boost at those revs. Gains of up to 90hp below 5000rpm, with slightly higher peak power on the same boost level!

[steve murch]

well i did answer it
i also said why the chose of a split pulse hsg isn't always the best, not the be all to end all.
there is so many variables from setup to setup along with tuners in how they get a result,i like yourself go by what I have done over many years.
so long as you get a gain who cares how you do it.
but i would scan the the SAE site or become a member like i have and submit your theories and results to which are spread around the world,theses some great reading on there.
but i also only believe what i see in the real world along with what else is done to achieve the gains,as much as you may have changed from one hsg to another or manifold design other things change in the process.
so its not totally conclusive that the hsg alone made the gains.

[Lith]

Yeah I understand there are always a few variables, though its pretty hard to be sure where to draw a line in terms of where one contributing factor ends and another starts in terms of substantial changes in performance after changing a setup - I know there are always gaps in the understanding of these things, the trick is finding them....

... and on that note, thanks for the tip - will check it out

[steve murch]

Yeah I understand there are always a few variables, though its pretty hard to be sure where to draw a line in terms of where one contributing factor ends and another starts in terms of substantial changes in performance after changing a setup - I know there are always gaps in the understanding of these things, the trick is finding them....

... and on that note, thanks for the tip - will check it out

a few? the variables are endless and experiance is how you figure them out as very few if any books will tell you ( maybe soon )

[Lith]

I didn't mean that literally - I usually understate things like that, and I guess to more accurately put across what I was thinking about it I should have put "hidden" in front of that particular noun.

[Dell'Orto]

In summary Lith, you should buy a 20B.

[steve murch]

In summary Lith, you should buy a 20B.

i like that

[Lith]

On the topic of rotaries and twin entry turbos:


It was originally on a snow mobile but now wears a 1.06a/r twin scroll hotside and will be going somewhere far more sensible - on the side of a ported 13B in a Series 5 RX7. Should make for a fun street/track hack

[steve murch]

pretty common these days running them street and race