For those of you that haven't seen my build thread the motor being built is a 95 block fully forged internals and a 2002 VVT head that is getting oversize valves ported and polished. Currently I have Matt at hella fab building a tubular manifold for a twin scroll EFR. Im committed to the twin scroll manifold but starting to wonder if it would be a poor choice doing the 7163 TS. I talked to Andrew and trackspeed and got a ton of information about turbos and would like to get the opinions of the MT.net community.

What data point would you guys like to see me be the test mule for? EFR 6758 TS or 7163 TS?

Which turbo do you thing would preform better and why?

The twin scroll turbos are a B2 housing and .80 AR
The single scroll 6758 is a B1 housing and .64 AR

 

Would love for you to try either flavor of the TS, and the 7163 only if you're going for insane power. Running it at low boost would be a huge waste. I'm already testing the limits (we are literally running 100% boost duty, #ALLOFIT) of a SS 6758 on psyber's car so no need to test that
TS 6758 might be interesting.

 

The power goal is 400-450 which should be doable with a 6758 so ive started leaning away from the 7163 TS and more towards the 6758TS. The 6758TS would give a really good A/B comparison on turbos. What do you think the spool differences would be between the turbos?

 

Dont' think you're gonna see a whole lot, esp with a long tube mani. Maybe 200-300? would be my guess

 

go big or go home, 7163.

 

Dont even consider the 7163 unless your power goals are substantially over 500.

Twin scroll 6758, e85, easy 470. Done.

 

Conjecture or do you have some data that we don't know about?

We see Single scrolls up the wazoo. It'd be good to compare a similar turbo with the difference being the flange. However a/b is going to be hard to do because everyone has different piston/head builds and even health of the motor and intercooler flow.


I vote 6758 ts. Be the first. You can always swap to a 7163 ts for A/b data
​​​​​​

 

I was about to say: a 7163 won't even make "substantially" over 500. At absolute full tilt it can make 600. At 28-30psi

 

I just start wondering how to tell if the heads really do become limitations or not.

 

I change my vote. 7163 twin scroll.

The 6758 already has great response, the ts version is just more of it.

Might as well use the ts on a larger turbo for better top end, and might just have similar spool to a 6758 t25.

Dooo eeeet

 

400 is more than doable with even a 6258 with the twin scroll housing...

If that is your power goal, all you're getting by moving up in size is reduced response and worse spool/boost threshold.

 

it certainly looks that way from your car/tune. 6200+ and VE drops hard

 

But by how much more? Can you quantify this or are you bench seat racing? We have zero info on this.

Where have you seen a comparison of a 0.64A/R T25 against a 0.80A/R T4 twin scroll?

Your comments are just speculation. If the A/R where matched then sure, the twin scroll would undoubtedly respond faster. Until someone throws one on the dyno, we won't know for certain in this case.

 

 

 

Does a 0.64a/r run out of breath up top, or is it the head.

 

judging by this
https://www.miataturbo.net/prefabbed...0/#post1481183

a much better head netted at least 25 up top. but iirc it's still on stock cams so there's that.

 

So is a larger a/r an alternative to port work and +2 valves, or will the turbo be struggling up top because of the head.

This is the question I have. I don't really care about Audi and other motors because a comparison to those is moot. It'd be nice to see real world data on miata engines to compare instead of this speculation party.

 

Ultimately, your largest restriction becomes your limit. It all has to work together, it all has to flow together. If you can't make the boost, if you can't ingest the boost, if you can't evacuate the gasses, if you can't.........you get the point.

I won't derail this thread much more so I'm bowing out, and eagerly awaiting your results coming soon as well as OP's, whichever flavor he chooses.

 

I'm not disagreeing , I just don't understand the notion that a larger A/R magically means more top end. On the extreme we have the case of a 6x58 on a 0.85 housing that was slow as *****. Granted it was Single Scroll, but like you said, balance.