Gt3076R Antics , Better Late Than Never .

[34GeeTeeTee]

Worlds longest turbo fitment.....

[Dose Pipe Sutututu]

I've gone through 3x cars already

[GTScotT]

I've built 3x cars already.

I even whittled the blocks from cast slabs.

[34GeeTeeTee]

I've gone through 3x cars already

I've built 3x cars already.

I even whittled the blocks from cast slabs.

[discopotato03]

Exhaust finally fitted today and looks good from underneath . Consists of 3.5 dump to 3.5" 200 cell XForce metal cat which tapers to 3" for the cup joint and the rest of the system . They used the largest longest straight through mufflers that physically fitted - the rear one is 20" long . The outlet is a straight section of polished 3" stainless tube .

I asked for quiet and that's what I got , if anything it's a little too quiet and I didn't previously think that was possible with straight through 3" mufflers .

If you can remember what a factory std VL NA sounded like it's a little louder than that .

The old exhaust is a HKS one and available if anyone wants a cheapy . The ceramic cat is in good nick internally with its matrix very clean at the temp sensor end .

I'm interested to see if mixtures and consumption changes much , also turbo transients .

A .

[Dose Pipe Sutututu]

Photos!!!

I'm after a more quiet exhaust too, although a stock VY V8 makes more noise than my car

[wolverine]

A big arse muffler like that with a mid muffler will be uber quiet like my Stagea. Now time to give it the beans.

[discopotato03]

Went for a quick spin down to the Burg on the Princes Hwy last night and it's easier to live with noise wise , could easily drive for long distances now .

The turbo transients are a bit better and the engine "comes alive" a bit more in the 2800 plus area . What is showing up is how sensitive it is to fuel mixtures at part throttle as it climbs onto boost , if its out it's not terrible but it loses a bit of torque just at the transition point . It's this that makes me think sometimes that MAF systems could be better than MAP sensed ones because the difference in air flow may give a bit more tuning sensitivity than a MAP sensor reading relatively slow pressure changes .

Also I'm using manifold pressure for accel enrichment ATM and may have to go back to TP , neither is perfect .

Photo wise there isn't much to see , I think the ovals are Redbacks and the rear is the largest they do in 3" from memory . You might find it a bit too quiet for your liking .

I have to see Kirawee Mufflers this morning , real easy to find . If you know where Just Jap is walk down to the roundabout and look across to the left on the other side of the road can't miss it .

A .

[zebra]

Yep I remember my 25 liking it real fat coming onto boost

[Lithium]

Went for a quick spin down to the Burg on the Princes Hwy last night and it's easier to live with noise wise , could easily drive for long distances now .

The turbo transients are a bit better and the engine "comes alive" a bit more in the 2800 plus area . What is showing up is how sensitive it is to fuel mixtures at part throttle as it climbs onto boost , if its out it's not terrible but it loses a bit of torque just at the transition point . It's this that makes me think sometimes that MAF systems could be better than MAP sensed ones because the difference in air flow may give a bit more tuning sensitivity than a MAP sensor reading relatively slow pressure changes .

Also I'm using manifold pressure for accel enrichment ATM and may have to go back to TP , neither is perfect .

Out of interest targetting AFR wise in that area? And how are you sure it's not timing that is partly to blame for the softness? There are all kinds of ways of going about the whole transient throttle tuning to get it right though, definitely where the "art" is to tuning I reckon - making good power reliably is a bare minimum.

What is left on the to do list before it hits the dyno? And are you going to have a comparison with the GT-RS?

[discopotato03]

EV14 injectors hopefully in a GTt fuel rail but spending a bit quick ATM , Lancers up for rego soon and we get bitten pretty badly for that in Sydney .

I didn't get a graph for the GTRS tune and a fair bit changed since then , everything after the AFM to behind the cat grew and what's behind that flows better and is quiet .

As predicted , ATM anyway , there is no comparison between the GTRS and the GT30 but that's not to say that the 30 is a laggy pig . Obviously taking some restrictions out of the system that weren't so obvious with the GT28 has helped overall and it would have been interesting to see how it would have been with a better exhaust .

These 3076Rs are interesting at this point because they make an RB25 a more evenly rounded package even though they don't stick much boost it till a little before 3000 revs . I understand why people see them as being progressive over the rev rage where smaller turbos snap on and get things out of shape . I suppose if you drove around with your foot buried all the time these force you to wait a bit till they get cracking , don't think you'd get away with that for too long in these parts .

My current impression is that's it's still boarder line a smidge big but not by much , if you get my meaning not really laggy but a little more shove a little lower down would be good . Don't want to open old sores but this is where a slightly lighter slightly smaller trim turbine would have paid off . The GT28 turbine was a little small where the GT30 84T is a little big and Garrett don't want to give us the lighter smaller trim 60mm NS111 turbine .

Scott hinted these injectors aren't exactly high tech but that's because I'm fussy about fuel transients at small pulse widths . Fine for most people particularly with ethanol but when you want it virtually like factory or better they fall a little short . I think why the EV14s do better is because the moving parts are shorter and lighter than earlier designs and this makes them easier to control at small pulse widths .

[Lithium]

These 3076Rs are interesting at this point because they make an RB25 a more evenly rounded package even though they don't stick much boost it till a little before 3000 revs . I understand why people see them as being progressive over the rev rage where smaller turbos snap on and get things out of shape . I suppose if you drove around with your foot buried all the time these force you to wait a bit till they get cracking , don't think you'd get away with that for too long in these parts .

My current impression is that's it's still boarder line a smidge big but not by much , if you get my meaning not really laggy but a little more shove a little lower down would be good . Don't want to open old sores but this is where a slightly lighter slightly smaller trim turbine would have paid off . The GT28 turbine was a little small where the GT30 84T is a little big and Garrett don't want to give us the lighter smaller trim 60mm NS111 turbine .

Scott hinted these injectors aren't exactly high tech but that's because I'm fussy about fuel transients at small pulse widths . Fine for most people particularly with ethanol but when you want it virtually like factory or better they fall a little short . I think why the EV14s do better is because the moving parts are shorter and lighter than earlier designs and this makes them easier to control at small pulse widths .

Yep well familiar with the injector design stuff, including fussiness - I love the Bosch injectors.

I think you misinterpret some of the disagreements stuff we had on the turbo side of things still, but nonetheless it sounds like we are actually on more of a same page than you realise - I never said these things were magic at low low rpm, but they are also more streetable then you seemed to think they would be. I dislike the .63a/r housing for higher flow but at the same time I always thought a 0.82 would be a bit big for your liking, the likes of a 0.73 would probably be closer to the right kind of cup of tea for your tastes and would probably change the character just that little bit. What you are experiencing now will be probably close to as good as you are going to get, I hope it's liveable or proves justifiable when you get a full power tune and get to explore the full rev range and how the checks and balances land. Have you actually had it WOT with a bit of boost yet?

[Dale FZ1]

Wait until he does, and has first hand experience how well it works, and over how wide a range.

Previous post suggests its a slow process of expanding the rpm/load envelope but he's getting the picture...

[discopotato03]

Yep totally agree on the 0.73 housing , HKS did them in T2 flange but no IWG .

I don't hate it fellas it's just that driving in built up areas with mostly 50-70 km/h limits means getting around at sub 2800 revs much of the time .

No I don't wind this thing up much because it isn't properly tuned for the 50 50 E42 splash blend it runs , if the injectors allowed it I'd probably run straight 98 pulp because it gets better at low revs and part throttle the higher the petrol content gets . I've been down to about E25 but at real low revs and pulse widths around 1-1.5ms you lose mixture control and have to raise the idle to ~ 1000 revs . This thing should be able to idle at 650-700 on PULP and with better injectors I think it will , the ViPec tries hard but the squirters get sleepy .

Good injectors and tuning will get the best out of this turbo , hopefully best will be good enough in the rev ranges it spends most of its time .

A .

[Badgaz]

pssh just drive around in 2nd

[Dale FZ1]

Running a auto-spec diff 4.363 ratio will claw back a large proportion of any drop in low-speed response when driving in built up areas in the higher gears. Make the car a better thing in most ways except possibly a steady 110km/h motorway cruise.

No need or desire to run the thing in 2nd gear.

[discopotato03]

I gather the standard air box and snork , with a dormant Z32 , wouldn't make any difference up to 300 wheel wasps ? Intake is Scottys 80mm with a silicon step up to 100 at the comp housing .

Will have a look at the timing map today to see where its at in the boost threshold area . Is anyone running a similar setup prepared to give some ballpark timing numbers in the 0-10 pounds boost 2500-3500 rev area ?

A .

[Dose Pipe Sutututu]

Sure, here's mine - not the same turbo, however very similar in many ways.

1.2 bar of boost in 4th at 3800-ish rpm - timing map is for 98 RON and with knock monitoring I can't hear anything. However this is consider very mild timing as I punched these in before the track day and only have touched it up here and there.

[discopotato03]

Much of my map has a bit more advanced timing than that one though as I mentioned I run a 50 50 mix of 98ULP and United E85 . Back in a sec ...

Edited April 18, 2014 by discopotato03

[discopotato03]

This