The 2H/12H-T/1HZ/1HD-T/1HD-FT Gturbo Alternative Tech Thread (2 Viewers)

[vwluv10338]

@diby 2000

This is what Luke told me in an email about mine.
"After a few different combinations the wheel I selected was a 7+7 compressor wheel with an inducer of 48.0 mm and a Exducer of 67.0 mm. The reason I retained the 7+7 is that they will out spool an 11+0 compressor wheel (this allows me to use a larger compressor wheel and get similar if not the same performance as a smaller wheel) and the 67mm Exducer with the anti-surge slots give upper rpm flow to keep the turbo operating in the efficiency rating from 72 - 65% so your intake temps stay lower and your inter cooler will be more efficient and not get excessively hot. All which leads to a denser air intake charge which means you can burn more fuel and make more torque."

In our recent conversations he decided to bump my inducer from 48mm to 50mm on the replacement turbo.

 

[gerg]

I doubt it's your compressor causing sluggish response. The vast majority of a sluggish turbo is from the hot end of things.

 

[Dougal]

No I do not have the spool AFR numbers.
The advertised compressor wheel is 53.5mm inducer, 70.5mm exducer with a 0.6 AR housing.
I didn't measure my inducer. @vwluv10338 got a smaller compressor wheel. 68mm was it?


Fair call. You have much more experience than I do.


So it kind of works the way I was describing on the previous page yeah?

53.5mm intake is a massive compressor. About the size of a Holset HX35. It will choke around 55 lb/min flow.

I think a compressor like that will be in surge or extremely poor efficiency at all normal operation of a 4.2L diesel. It will really struggle to make and hold any low end boost. It is only suitable for high boost at high rpm. Everything else will suck.

Yes excessive EMP does what you think. To know what's excessive you compare to boost.

 

[gerg]

Yeah it's a bit of a weird idea to address this issue. I have a strong feeling it won't fix it.

 

[Dougal]

@diby 2000

This is what Luke told me in an email about mine.
"After a few different combinations the wheel I selected was a 7+7 compressor wheel with an inducer of 48.0 mm and a Exducer of 67.0 mm. The reason I retained the 7+7 is that they will out spool an 11+0 compressor wheel (this allows me to use a larger compressor wheel and get similar if not the same performance as a smaller wheel) and the 67mm Exducer with the anti-surge slots give upper rpm flow to keep the turbo operating in the efficiency rating from 72 - 65% so your intake temps stay lower and your inter cooler will be more efficient and not get excessively hot. All which leads to a denser air intake charge which means you can burn more fuel and make more torque."

In our recent conversations he decided to bump my inducer from 48mm to 50mm on the replacement turbo.

Whoever said the anti-surge slots add more airflow is talking out their rear.

Anti-surge slots are to allow air to recirculate without the damaging surge waves at low flow and high boost. They don't do any of the things claimed above.

 

[mudgudgeon]

@diby 2000 @vwluv10338
just wondering what the dimensions of your turbine wheels are?
You might have already posted, couldn't see them after a little digging.

 

[mudgudgeon]

53.5mm intake is a massive compressor. About the size of a Holset HX35. It will choke around 55 lb/min flow.

Similar to garrett gt3071.
It has 53mm inducer, 71mm exducer.

From distant memory Z()ltan was running this in his racing HZJ75 on a 1HZ, revving to 5500+ RPM
May have been gt3076. Either way, it was "here for a good time, not a long time" kind of deal.

 

[gerg]

See now driving that turbo with rpms like that makes sence to me. It's when you get so close to the surge line you rely on anti surge ports to get by seems unwise. When I map and get close to the surge Id get a different compressor. To what extent do anti surge ports offset the surge? 100rpm...200rpm....500rpm? It's like buying insurance for an unknown amount and feeling like you've got it sorted out.

 

[mudgudgeon]

See now driving that turbo with rpms like that makes sence to me. It's when you get so close to the surge line you rely on anti surge ports to get by seems unwise. When I map and get close to the surge Id get a different compressor. To what extent do anti surge ports offset the surge? 100rpm...200rpm....500rpm? It's like buying insurance for an unknown amount and feeling like you've got it sorted out.

Correction on my memory above. Z()ltan had a gt2876r. Bigger compressor again, but smaller turbine.

 

[vwluv10338]

Luke had said this turbo was based on the GTX3071 gen 2 with some changes. I found this posting from a few years ago by Graeme.

"
Whether you consider it good or not depends on what your criteria is.

Certainly from a peak power perspective especially when running quite rich (15-17:1), the GT3071 56 trim is about perfect for 2200rpm and up. Will make huge power. 230kW at wheels is feasible.

The GT2871, is initially more responsive (under 10psi boost) than the GT3071, flattens for a bit then comes on hard at 2200rpm with slightly higher afrs than the GT3071, then chokes in the high rpm - max ~ 185kW with sane compressor (56 trim)

GT2860RS is the best of the three, afrs are better (16-18:1), and up to 18-20psi. But, laggy unless rich. 150rwkw max using a 0.64 A/R exhaust housing.

A rich running TD42 Nissan maybe it's ok (to some), but a 1HZ... They need to be cool, 20:1 afrs min (in my opinion).

The GTX range is even worse than the GT range for diesels according to some of those experienced in fitting the Garrett range."

 

[diby 2000]

@diby 2000 @vwluv10338
just wondering what the dimensions of your turbine wheels are?
You might have already posted, couldn't see them after a little digging.

As far as I'm aware, we have the same turbine, housings and core as the advertised turbo, just different compressor wheels.

Good find @vwluv10338
Not exactly positive news for us but good info all the same.
I hope we can prove that the changes make a big difference.

 

[vwluv10338]

As far as I'm aware, we have the same turbine, housings and core as the advertised turbo, just different compressor wheels.

Good find @vwluv10338
Not exactly positive news for us but good info all the same.
I hope we can prove that the changes make a big difference.

Not sure how much difference the gen 2 would make as that post from Graeme is years old. @Rob1983 is the one to ask about running at GT3071 because I believe he had one on his truck.

 

[MonsterCruiser]

Luke had said this turbo was based on the GTX3071 gen 2 with some changes. I found this posting from a few years ago by Graeme.

"
Whether you consider it good or not depends on what your criteria is.

Certainly from a peak power perspective especially when running quite rich (15-17:1), the GT3071 56 trim is about perfect for 2200rpm and up. Will make huge power. 230kW at wheels is feasible.

This definitely makes sense for the performance I've seeing from my MMP turbo. Lots of power when running over 2k rpm and as I mentioned before the truck runs really nice at 100km/hr where as with the stock turbo it felt like it had nothing left when I'd hit hills at that speed.

 

[vwluv10338]

This definitely makes sense for the performance I've seeing from my MMP turbo. Lots of power when running over 2k rpm and as I mentioned before the truck runs really nice at 100km/hr where as with the stock turbo it felt like it had nothing left when I'd hit hills at that speed.

Exactly my feelings having my stock turbo back on. I did have the MMP turbo starting to spool at around 1250 Rpms (green light coming on) but I still don't have an intercooler and am running the stock pin. Also, the posted dyno truck also had a modified air box. I need to get my intercooler finished. Then get AFR readings and order a cap and pin set that I posted in the tuning thread. Then install a Duramax 4" air box. Then compare where I'm at to the posted numbers which still were from a fte. Towing my boat yesterday I could tell my stock one has less low end as it's harder to tow and blowing a huge cloud of black smoke before the turbo spools.

 

[Dougal]

So dyno queen turbo?

 

[Tapage]

Call from the past .. but anyone here running a 2860RS map makes sense .. just looking to know any real world experience .. ( always curious )

 

[mudgudgeon]

I think 2860rs was probably the best match from the Garrett catalogue back in the day. It was used a lot on TD42 nissan and 1HZ.

 

[Rob1983]

3071 was very laggy down low, but once on boost was great. I went away from it in the pursuit of better drivability

 

[Tapage]

I think 2860rs was probably the best match from the Garrett catalogue back in the day. It was used a lot on TD42 nissan and 1HZ.

I didn't see any superior model on the catalog so far ..

 

[Mcreight911]

You need to pump numbers to this "higher emp" statement. Otherwise it's meaningless.

For my numbers, a turbo that delivers EMP lower than boost (at 1800rpm) with a hot turbine can deliver EMP of double boost while accelerating to higher rpm with a cold turbine (40psi EMP, 20psi boost).

The 40psi EMP is not a problem that needs solved. It is the only way turbine can extract power from cold exhaust gas. Anything you do to reduce that 40psi (i.e. weaker wastegate spring) will reduce the performance of that turbo in that condition. Reducing boost and richening AFR.

Turbines are driven by temperature, pressure and flow. Reduce any of those and you reduce their power.



Hang on a minute. I did not say "assumed", I said "approximated". Approximation in this case is by calculation. But there's no point doing that unless you are worried about over-speed.

Excessive EMP does kill power. But EMP is also what drives your turbo. Try to kill EMP and you've killed all boost.

Doing things to drop EMP (like using weaker wastegates) have consequences for turbine power and boost. The only single thing you can do to improve EMP while not hurting turbo performance is to find a more efficient turbine for those operating points.


Wastegates do not change a turbine map or characteristics. All they do is bypass exhuast to control boost.


That's it.

I have a good example here of a particularly badly suited turbine that I built to a turbo and fitted anyway. At 3000rpm with 15psi boost it was taking 60psi EMP. The engine produced no power and that was all the boost it could produce.
Same turbo compressor with a better suited turbine and it was around 25psi EMP for 20psi boost.
I've fitted a larger turbine housing to the same (better) turbine wheel and compressor for another test but unfortunately mislaid my EMP gauge at the time so I have no EMP numbers but they were lower.
Top end power was great, low end sucked. Turbine could not choke the exhaust enough to generate enough EMP to produce enough shaft power.

The bigger turbine housing also bought lower fuel economy. Mainly because I had to go down a gear more often.



No it can't. Follow shaft speed lines on a compressor map. To change compressor speed you're moving between these lines which changes PR (boost).

"Generally "I like to see drive pressure below 1.4:1 with waste gate turbos . But some will run to 1.8-2:1 without being detrimental to performance . But if you can get the same performance from less boost/drive pressure then why not .

I've seen power drop off with just 30psi back pressure yet some fine at 50psi

Correct you can't get better boost response with a light spring without adjusting fueling, or at least I can't .This is where r&d time is spent getting the balance

I tune how the customer wants but I like to have minimal smoke . Pump setup makes a massive difference to feel/drivability torque rise and torque holding ability. A WELL mapped pump with a well matched turbo and all the good bits (proper intercooler and intake ) can run richer than what I would normally but still have good egt's e.g never get worryingly hot .

I'm lucky between the turbo builders and pump builder I use, I have very little work to do.

It may have been something else going on but I have seen shaft speed change and boost stay the same, I assumed there was a restriction, volume changing but pressure not . This only on setups with big flowing compressor and stock intakes and also with eiexcessively light waste gate springs that are unable to hold boost at high rpm and with excessively high tension springs with drive pressure above 2:1 .

Got to find the balance, manage
Drive pressure, maintain sufficient emp and maximise fueling .