SIMBADS TREAD

[k31th]

They are slightly different bolt spacing on the head connection between FG and BA/F, I think.

[Puffwagon]

Which is the different part? I had no issues with bolting my bf intake and exhaust to an fg head.

[k31th]

I'm pretty sure it is... but I could be wrong, though

[Puffwagon]

The only difference I know of in that area is the fg turbo manifold t3 flange is in a different location.

If you're using a 6 boost manifold with an ex gate that wouldn't matter anyway as you'd be making custom zorsty dump bits.

 

Obviously a different bolt pattern matters but the fg head I used, which came from a gas motor, was the same as the bf head, as far as the manifolds fitting.

[SIMBAD]

It’s t4 to suit the turbo with 60mm tial gate.

v band on the dump I’m pretty sure. Maybe even 4 bolt.

so all I’d need to do is modify my nizpro dump and plum back for the external gate. 

 

I thibk my brother want to keep his 60mm gate though so maybe for me a 45 or 50 would be better? 

[Puffwagon]

It depends how much boost you are planning to run and what size turbine housing is on it too.

Being that the hotside is bigger than a stock turbo and the compressor flows a touch less than a gen2 gtx3582r you should be fine with the smaller gate if you have one lying around.

You can't really go wrong with a bigger gate but you can go wrong with a smaller gate.

 

That aside, I haven't used one and it may well benefit from the larger gate as far as exhaust pressure to intake pressure goes.

 

Here is a calculator for figuring this stuff out.

 

This is roughly what it works out to be.

[SIMBAD]

So what’s an acceptable exhaust manifold to intake manifold ratio?

 

looking at that calculator. Which is about all I did lol 

the turbo specs look right. I messaged my little brother and he had no idea what the turbine a/r is but is certain that it is also twin scroll set up.

 

I did gather from that calculator that maximum was around 34-35mm waste gate to flow enough? 

But yeah better to go over then to be under sized and be on the edge

[Puffwagon]

That'll vary but 2:1 down to 1:1.

 

While you can calculate and optimise stuff it doesn't have to be perfect.

 

Just slap a 50 or 60mm gate on and be done with it. 

Edited 24/10/18 06:44 AM by Puffwagon
A word

[SIMBAD]

100 percent. Can’t go wrong there. The old KISS method is the go for me. I’ll keep an eye out for something around that size of my brother goes ahead with his plans

 

Also with boost pressure I am unsure. I’d like to be in the 400 club when I turn it up but would be happy with 350 for everyday commuting. I was tossing up on 12psi or 15psi spring initially with ported flapper mod done. I’ve read some get over 400 with the 12psi spring and others then the flap starts to lift before getting to 400 as well. So yeah this 6boost/Borgy combo has thrown a spanner in the works. I know that set up pulled 550odd rwkw on e85

 

what is better to target? Power figure or boost number? Is there a relationship there for what’s better for my bf2 motor? I always thought that more power made on less boost would be more desirable?

 

or say, 18-20psi and what ever it makes it makes. 

 

Then be worried about the zf input shaft.

Edited 24/10/18 06:55 AM by SIMBAD

[Puffwagon]

More power on less boost is better to an extent. It depends if you want a super responsive car or are happy to wait a bit with a bigger turbo.

 

Being external gate the whole flapper mod isn't relevant, as this is something done to the internal gate to enlarge it and help it flow better.

 

Spring choice is somewhat of a preference here. If you choose a 15psi spring then the lowest boost you will be able to run will be 15psi. Restrictions can lower this a marginal amount like 1psi, but as a general rule the spring you choose will be your minimum boost.

 

A 12 psi spring will be fine as you can generally get double the boost pressure from the rated spring. If you were to always run higher boost levels then the 15 will be fine too.

As far as the wg opening before the targeted boost there are a bunch of variables that affect this and it's quite a long conversation to get through.

 

You wanna target a power figure but you can't just keep winding boost into a motor if it's not making decent power gains. 

 

You should be in the 400 club on 98 with 19psi give or take. I wouldn't feel comfortable taking my car further than that on 98 as it's kinda on the limit of what the fuel can handle.