VF Turbos what you need to know in laymans terms

[boon]

 94 Leone said:

See; I like my little VF28; comes on strong and oddly held quite well down the 1/4 mile, though I didn't really watch the boost gauge; I was watching the rev counter and listening for just in case something broke. Should have watched the boost gauge....

-It felt like it held well though.

See, you say that... but when you go to a big turbo, where the torque stays flat instead of being a big spike between about 4-5krpm... you know that initial pull you get when it comes on boost, and pushes you into the seat? A big turbo you just keep getting pushed into the seat, it's more similar to a plane taking off. It's very addictive.

[Johnnynz]

Need that in my life...

[ADIKT]

 Johnnynz said:

Need that in my life...

Oh god I can't wait

[94 Leone]

 boon said:

See, you say that... but when you go to a big turbo, where the torque stays flat instead of being a big spike between about 4-5krpm... you know that initial pull you get when it comes on boost, and pushes you into the seat? A big turbo you just keep getting pushed into the seat, it's more similar to a plane taking off. It's very addictive.

I have a 20g TD05 on my legacy, I know how addictive it is.- though that being untuned it boosts late bout 4500 RPM at 17PSi.(However doesn't drop a bit to redline)

I like the VF28 on the Rex, 16PSi at 3500. I want to find the perfect balance between responsive and too big.

[boon]

I reckon that point is around a GTX3071R on a 2L. Great spool but it will pull properly all the way out to about 7.5k

[Marky]

What we need is to chuck these turbos on an engine which will spool them properly

[94 Leone]

 Marky said:

What we need is to chuck these turbos on an engine which will spool them properly

EZ30. okay. If we all donate a dollar...

Surely we may have enough to build a clubsub test rig haha.

[boon]

 94 Leone said:

EZ30. okay. If we all donate a dollar...

Surely we may have enough to build a clubsub test rig haha.

No, something with exhaust runners that aren't a meter long.

Why do you think a 4G63 can spool a larger turbo considerably faster than an EJ20?

It's because they can have very large diameter runners (flow) without them being a mile long and taking ages to respond to transient changes in pressure.

An RB30 or 2JZ will always spool a turbo way faster than an EZ30... unless you go front'n'low mount but that's a mission.

[Simon C]

 boon said:

No, something with exhaust runners that aren't a meter long.

Why do you think a 4G63 can spool a larger turbo considerably faster than an EJ20?

It's because they can have very large diameter runners (flow) without them being a mile long and taking ages to respond to transient changes in pressure.

An RB30 or 2JZ will always spool a turbo way faster than an EZ30... unless you go front'n'low mount but that's a mission.

Agreed, the stock EJ setup has a tonne of pipework to pressurise. Hardly the best design for spool. That's why the R35 GTR has its turbo hotsides cast into the exhaust manifold, likewise the turbos on the current VW Golf GTIs and Rs. Low mount turbo on a Subaru is $$$$, needs heaps of custom pipework, lines, scavenge pump, etc.

I was planning on getting a JDM GRB STi when I get back to NZ next year and do some upgrades to it. Want to keep the spool and transient response as close to stock as possible, but be able to use the entire 8000RPM of the EJ207 without running out of puff. I was planning on seeing what Steve Murch could do to upgrade the stock one, but given what you've said (no ability to upgrade to BB CHRA, limited options for wheels and housings), I might be better off to go straight one of the available aftermarket twinscroll options. Pity none of them are cheap. Thinking Borg Warner EFR 6258 (requires work to fit) or possibly the Litchfield LM400 (but that's $3k+). IHI RX6R would be wonderful but the price is insane. Other suggestions welcome.

[rex7]

heard about twin scroll blouch 2.5xtr is pretty good, used Garret BB core.

[Simon C]

I thought about their TS 1.5 XTR, but I've heard stories that their turbos are generally slower to spool than their specs suggest.

[boon]

 Simon C said:

Agreed, the stock EJ setup has a tonne of pipework to pressurise. Hardly the best design for spool. That's why the R35 GTR has its turbo hotsides cast into the exhaust manifold, likewise the turbos on the current VW Golf GTIs and Rs. Low mount turbo on a Subaru is $$$$, needs heaps of custom pipework, lines, scavenge pump, etc.

I was planning on getting a JDM GRB STi when I get back to NZ next year and do some upgrades to it. Want to keep the spool and transient response as close to stock as possible, but be able to use the entire 8000RPM of the EJ207 without running out of puff. I was planning on seeing what Steve Murch could do to upgrade the stock one, but given what you've said (no ability to upgrade to BB CHRA, limited options for wheels and housings), I might be better off to go straight one of the available aftermarket twinscroll options. Pity none of them are cheap. Thinking Borg Warner EFR 6258 (requires work to fit) or possibly the Litchfield LM400 (but that's $3k+). IHI RX6R would be wonderful but the price is insane. Other suggestions welcome.

STM getting very nice results with the HKS GT28RS kit. Stock-like spool with ~260+wkw (on their ego-crushing dyno) and pulls through to close to 8k.

[johnny5]

yea was gonna say good results on the hks but 5k for the kit

[Guest]

Reading something interesting somewhat smart said the other day in relation to pipe size etc mightve been paul/22b but wasnt on there. Will see if I can dig it up.

I want to see some of these 260wkw GT28RS results the wheel sizes are smaller than TD05 16g. Providing these are the wheels sizes in q.

GT28RS - Comp 47.244/60.198 Turbine 53.848/46.99

TD05 16G - Comp 48.3/68 Turbine 55.8/49.1

[Koom]

 evowrx said:

Reading something interesting somewhat smart said the other day in relation to pipe size etc mightve been paul/22b but wasnt on there. Will see if I can dig it up.

As well as having rather long exhaust primary length, the ej engines have quite a short stroke which doesn't help with spooling a turbo.

[Simon C]

 Koom said:

As well as having rather long exhaust primary length, the ej engines have quite a short stroke which doesn't help with spooling a turbo.

The flip side of that is that we get nearly 8000RPM to play with in STi form. But yes, the FA20 is a square design with a factory "low mount" manifold design, so much better suited for spooling a turbo as is the fashion with engines these days.

[Guest]

This post:

I appreciate that a short manifold means larger diameter primaries for the same volume, and this will lift peak power, but the mean gas velocity will still drop with larger primaries, regardless of length.

http://www.lancerregister.com/archive/index.php/t-25055.html

[A_J_T]

Should sticky this if we can, cheeky thing was hiding 4 pages back.

[Guest]

Is on the new sticky tree but yea there you go be happy.

[borland667]

Hey folks, what are your thoughts around getting a VF28 with p20 housing to replace my stolen VF23 (these are hard to get!)?

[Guest]

 borland667 said:

Hey folks, what are your thoughts around getting a VF28 with p20 housing to replace my stolen VF23 (these are hard to get!)?

Ive always found vf23 the easy one to find. Any vf will be fine p18 or 20. If you can justify the extra 50 for a p20 housing for no hugely noticeable gain do it. May lose some spool 100rpm odd.

[Zeke]

Great read thank you.

Hmmm I wonder how long my vf22 will last at 17psi and anti-lag

[boon]

28 minutes ago, Zeke said:

Great read thank you.

Hmmm I wonder how long my vf22 will last at 17psi and anti-lag

 

Longer than your uppipe, and possibly the headers

[Zeke]

Yea... headers are nice and blue seem to hold

[Guest]

14 minutes ago, Zeke said:

Great read thank you.

Hmmm I wonder how long my vf22 will last at 17psi and anti-lag

 

That's a question only you can answer if it fails ?