Couple Performance Questions

[Aaronbrook37]

Hey there all. I've been doing a little bit of research on trying to upgrade my B6T-swapped Ford Festiva motor a little bit. In particular, I'm looking at improving airflow through the intake/head/exhaust, and I have a few questions in that regard:

1. The JDM-spec intake plenum seems to have mixed reviews. Does anyone have hard data that the plenum/runners outflow the USDM equivalent? Further, would it be instead worth my while just to take apart and port out the USDM one instead? I'm aware of Rocketman's analysis of the two as well, but with my application, a stock ported one may work better given the limited space to the firewall.

2. Some people report that the SR20DE throttle body swap is super popular and a great way to increase airflow if you have the turbo and piping setup to support it, but there isn't a whole lot of documentation. Am I basically just looking for an early 90s G20/NX2000/SE-R throttle body? On ebay, they seem to have some specifically for automatic transmissions, but I doubt it makes a difference. Further, are these ones 60mm from the non-turbos? I read that the stock plenums and TPS can be adopted to these, correct?

3. How poorly/well does the OEM exhaust manifold flow? I'm tempted to pick up a build-it-yourself kit from either JGS or Weirtech, but I need to ensure it's a worthwhile modification for better power delivery first. Also, with a log-style manifold, do you think adapting the OEM heat shield would be possible? If not, I suppose I could just get it ceramic coated or treated theoretically.

Some people have used the Miata manifolds, but had the turbine flange modded and flipped for a bottom mount log-style manifold. It's an option

This interests me too if anyone has experience with it.

4. How many active members on here have B6T's and VF Subaru turbos in their cars? Whether that means complete or hybrid swaps... I'd love to hear from some of them on how much better it would be compared to a VJ14/11 hybrid that I am thinking about building instead. Is the spool outrageously slow/high RPM for example? Further, some people report great results with Nissan GT25 turbos... how are those compared to the VJ series?

[Iantboyd]

from my understanding a non-turbo b6 dohc head flows better than the turbo head, similar to the bp05 vs bp26.

[Aaronbrook37]

from my understanding a non-turbo b6 dohc head flows better than the turbo head, similar to the bp05 vs bp26.

Would this be the MX-3 head we're talking about? I've heard rumours about this swap being productive both in terms of the intake manifold as well as the head. I wonder if the two are interchangeable as my intercooler setup and airflow configuration basically requires a top-mount throttle body.

[Iantboyd]

I suppose the mx3 would qualify as b6 dohc non-turbo but i was also thinking non-turbo capri's.

[Aaronbrook37]

Bump!

[c.lozer]

I suppose the mx3 would qualify as b6 dohc non-turbo but i was also thinking non-turbo capri's.

so are you saying I can put a dohc mx3 or capri head on my b6 sohc block???

[bogaut]

Yes

[323GTX-RSA]

I just fitted a MX5/Miata head on my B6T and it runs well with it. Just need a welsh plug in the front cost 38c

[c.lozer]

but that wouldn't work with a non turbo block, would it?

[Iantboyd]

but that wouldn't work with a non turbo block, would it?

pretty sure the b6 works like the bp. the sohc and dohc blocks are the same, just a head swap.

[c.lozer]

just to get out of your hair, is there a certain place on this internet that has info on the bp/bf nterchangable parts? I'm not doubting you, I would just like to read more.

[Iantboyd]

This place isn't bad but you'll have to search it. otherwise the yahoo message group has info. And to be clear the bp is the 1.8 and the b6 is the 1.6. The only reason I mentioned the bp is because the 1.8 sohc and dohc engines share the same block, I also believe the 1.6 sohc and dohc engines share the same block.