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16v Twinscroll - worth it?

Tfrasca

Active member
Joined
Apr 20, 2015
Location
Ben Lomond, CA
I'll be slowly building a 16v engine for my 140. My original plan was to use the stock NA manifold with a twinscroll j-pipe for my Borg Warner s252. I know this has been done successfully before. T3 twinscroll housings are available in sizes from .75 to 1.25 A/R.

That said, it would be quite a bit easier to make a non-divided j-pipe. I could then use a Borg Warner v-band inlet housing, which would further clean things up. Also, I wouldn't have to buy a second Tial MV-S. The two wastegate thing is the real bummer.

So, for people that have experience with twinscroll 16v 4 cylinders: is it worth the hassle?
 
Hi Tfrasca,

I also decided to go with a stock manifold and J-pipe on my 16V (still building).
This is after reading several threads on s?varturbo.
Many users there get very good response and high output using these J-pipe setups.
Stock 16V manifold flows well.
Based on what I have read: you can expect tp hit full boost up to 500rpm sooner with the same turbo and twin scroll.


You do not necessarily need a second wastegate.
You could run a divider up untill the gate, like shown in the following picture:

dual_scroll_8166e47b90d913bce8dca43c807c37c83b68c10c.jpg
 
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twin scroll means you can have faster spool up with a bigger hotside housing, so you getting better top end flow as well...
 
Remember that choking the engine with too small of a turbine housing will leave you with both worse spool and top end.
 
Remember that choking the engine with too small of a turbine housing will leave you with both worse spool and top end.

Yeah the .48 was too small, for sure. I was thinking about a .83 with a divided t3. I?m not opposed to a t4, it just seems huge.
 
Yeah the .48 was too small, for sure. I was thinking about a .83 with a divided t3. I’m not opposed to a t4, it just seems huge.

tates car makes 25+ psi on an 8v with the big twinscroll t4 housing at like 3700-3800 rpm with an efr7670
 
To make the same flow on a twin scroll turbine housing, you have to run a larger A/R than you would with mono-scroll on the same turbine wheel. Twin scroll places a wall in the middle of the flow area so it actually reduces flow capacity.
 
Another thing that I know is confusing: if you're comparing turbine housings for the same turbine wheel, and same A/R, the "T3" vs "T4" distinction usually only refers to the inlet flange and a bit of the entrance section. The volute (scroll) section could be identical if you're comparing housings in the same family made by the same manufacturer.
 
To make the same flow on a twin scroll turbine housing, you have to run a larger A/R than you would with mono-scroll on the same turbine wheel. Twin scroll places a wall in the middle of the flow area so it actually reduces flow capacity.

Good point. Thanks for that, as usual. I guess there's no real way to ballpark what size twin scroll equates to a single scroll, flow wise, since every one is going to build their housings a little differently. I sent a message to AGP to see what they think about it, maybe they'll have some info for me.
 
Look at head flow differences between your 8v and 16v. If it's a sbe a punchy turbo may be a detriment. High cylinder pressure low rpm=bent or broken connecting rods
 
Another thing that I know is confusing: if you're comparing turbine housings for the same turbine wheel, and same A/R, the "T3" vs "T4" distinction usually only refers to the inlet flange and a bit of the entrance section. The volute (scroll) section could be identical if you're comparing housings in the same family made by the same manufacturer.

I see this now with the BW T3 vs. T4. It?s just the bolt pattern on the flange. Right now I?m leaning towards a T3 1.00 twin scroll.
 
Look at head flow differences between your 8v and 16v. If it's a sbe a punchy turbo may be a detriment. High cylinder pressure low rpm=bent or broken connecting rods

Yeah I?m pretty sure my 19t is what bent my rods. I don?t think my BW turbo could ever be that punchy. Oh, I guess I should say I?m going to pass on that Beams engine. It would have been sick, but another redblock will be way easier.
 
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