low end power, 11441 vs 125

[Renze]

some 8 years ago when we test drove a 11441 we really didnt like the turbo lag, at 1400-1500rpm suddenly the turbo woke the engine up. Below it felt like way underpowered.

Reading tests of the Forterra 125 they measured 511 Nm at 1250rpm: http://edepot.wur.nl/167701

It seems like the later ones had improved turbo response... How do you get that on the 11441 ? Is there a boost pressure gauge on the fuel pump you can fool ? Or does the 125 use a different turbo ?

The test drive, while pulling up (accelerating turbo) gave an entirely different performance than what the tests reveal (lugging the engine down) Is it pump adjustment, or is there a hardware difference between early 1404 and late 1504 engines ?

 

[hve]

Hi Renze,
Without knowing anything specific about the two models you are comparing.....................
In general, turbo lag is caused by
1. Too smaller Exhaust and
2. Too bigger turbo (this is more complicated than it sounds)
if the turbo is designed correctly for the engine and the exhaust is not restrictive you should get minimal lag.

modern turbos spin at 180,000rpm so dont need to be as big as the old turbos from the 1980's that only spun at 80,000 rpm.
smaller compressor wheels will spool up much faster and greatly reduce lag.............. Lag is usually a much bigger problem on cars than tractors to be fair............. which i guess is why tractor manufactures dont spend much time trying to eliminate lag.

Unfortunately there is a lot of science behind the correct combination of Exhaust and inlet wheel sizing (both the Inducer and Exducer), as well as the angle (pitch) of the blades and the size of the housing all have a big effect).
I am no expert on Turbos, but i know many (cars in particular.... even as late as a 2002 Nissan GU1 Diesel 4.2 Turbo and a 2007 SsangYong 2L diesel Ute) that the factory made a complete balls up of turbo selection and many aftermarket turbos (properly selected) can make a dog of an engine perform like a race car by comparison.

The Garret Web page has some good tips on turbo selection.

all turbos are NOT created equal! ..... , most manufacturers use Garret or IHI or other specialist turbo manufacturer, custom made for the application....., if the turbo has the same name on it as the engine (ie Toyota, Nissan etc) it is most likely (with the odd exception) rubbish, ..... as car companies are not specialist turbo manufacturers, and are just trying to do it on the cheap by making it themselves.

 

[Renze]

It probably also has to do with the 114 having a water jacket intercooler, where the 125 is air/air.

All these engines use a variety of the CZ C14 turbo, but i cant find any more info on the differences. The C14 range came both with wastegate, and without, so there must be some differences in the turbines too... The science behind that is not my profession, so i was more interested into what parts need to be swapped with later models to reduce the lag...

BTW a John Deere branded wastegated turbo is also made by CZ, Zetors house supplier.. Only the VGT ones they buy from BorgWarner. (which have electric actuator failures)

 

[hve]

Interesting............. if they are not running a wastgate, then they have either used:
1. oversize turbo (to prevent over spooling at full power at max revs)
or
2. an exhaust restrictor to do the same.

as an example, Mid 80's Mazda 323 1600 DOHC Turbos, utilised a 1" (25mm) restrictor plate in the rear muffler flange to prevent turbo over spooling, if you took it out you gained almost 50bhp without doing anything else! .......... but then you needed to fit an external wastegate to stop the turbo from crapping itself.

So to answer your question, swap out the old turbo with no waste gate, for the later model turbo with the wastegate and the lag should be much better.
then fit a 3" Exhaust and you should start to boost at 1000rpm

While a 3" exhaust is good for 300bhp on a non turbo engine, (~2.5" = 250bhp and 2" = ~120bhp) with a turbo you need 3" for anything over 150bhp to stop lag..... but still ok up to 1000bhp

I good mate of mine in the performance tuning game builds up street legal 2L Mitsi Evo engines to make 400-500bhp.
he was the race mechanic for the NZ GT1 class, on an old Evo2 with a 2.2L engine making 750bhp! ......... but the gearbox only lasted a weekend ......... was still the class winning car 3 years running up against 6L v8 Holden's, a TVR Tuscan, and a V10 Viper!

 

[Renze]

I am not sure, but older parts manuals tell me there were 2 different turbos, and only one of the picture clearly shows a wastegate actuator... I cant imagine using a turbo without wastegate today, so it must be a smaller wastegate not as visible in the drawing... ?

Anyway, anything over 100hp certainly has the 2nd version.