Thread: Another 120 project begins

Originally Posted by Bush65

I'm going to hazard a guess that a compressor wheel with 40 mm inducer is not going to flow enough air and the 52 mm exducer will not give enough boost at reasonable efficiency for 200 HP, but that is simply my gut feel and may be wrong. You could always rebuild it with a larger wheel.

Originally Posted by Dougal

The vnt 25 turbo is ancient and a lot had been learnt about vnt design since then. While it works, any gt22 based vnt turbo will beat it for boost, power and economy.

You can get 200hp worth of air from the 51.4mm t25 compressor on our engines , but only just and as John said, it's not very efficient doing it.

I'm aware it's ancient... but that's the way I like it! It complements both the 120's vintage and that of the git driving it reasonably well!

I thought it should be good for 200hp (may be pushing the friendship a bit, dunno?). It was roumored to have been designed for a 1.8L petrol, but fitted to a 2.2L petrol that made 175hp, developing 15psi boost from 2100 RPM onwards. I came across a few threads of people using it in diesels without reported adverse effects on VNT vanes fouling (my greatest concern), on both direct and indirect diesels.

My gut feel was that the turbine may be a touch restrictive for high power applications and was potentially contemplating leaving a provision for an external wastegate in the T3 to TK100 flange adapter, but am not sure it's worth the effort. Worst case scenario it'll be good for 180 HP with reasonable efficiency, which will still be more than sufficient to maintain my 110km/h and overtaking goals, but should see marked improvement in boost availability at lower engine speeds, which is where it will likely spend most of its time. I also like the simple VNT actuator control - it has potential for a simple boost controlled setup, with a in-cab regulated vacuum line for actuation point adjustment.

Time will tell how it behaves. I always have my T3 to fall back on if I'm unsatisfied.

Originally Posted by justinc

Youngest Daughter who is quite good at these things tells me that those are Kanji characters, and as she will be learning those next year at school (A HUGE amount of characters to learn, around 3000 IIRC!) she can't tell what they are about, so sorry can't help with dates

JC

Thanks JC,

Good on her. My better half's done about 5 years of Japanese in a previous life (throughout high school) but she reckons her Kanji was never good. That and she's been away all week. :P

Bojan

Originally Posted by Offender90

Thanks JC,

Good on her. My better half's done about 5 years of Japanese in a previous life (throughout high school) but she reckons her Kanji was never good. That and she's been away all week. :P

Bojan

Rose is off to Japan on a school trip on Friday for 2 weeks, and is busy packing in the other room! As a 15 YO she is very hard working at her studies, so she'll no doubt get a lot out of it. Has a good grasp of languages in general, it will be a life changing trip for her I reckon

JC

I'm pushing my memory here, so some detail may be wrong. My recollection is that what was printed on my head was a month and year.

I don't recall seeing kanji characters, but that is how memory works - I would have just ignored them.

I understand that headbolts are OK to reuse on a 4BD1. The manual is not as clear on the 4BD1T bolts (to me anyway), as it has different torquing procedures for new and reused bolts on the 4BD1, while the 4BD1T only has one procedure. Also, 4BD1 and 4BD1T blocks appear to use different headbolts (or the difference could be related to the age of the engine and have nothing to do with turbo / non turbo).

I have a set of headbolts that came off the 4BD1T block, which have a "0" forged on top of the head. The 4BD1 engine I have comes with headbolts with a "12" on the head. Are these bolts different?

Three bolts from the "0" set have been stretched (by 4mm, 2mm and 1mm respectively on the photo).



Do I only replace the stretched bolts, and if so, do I replace them with new "0" or used "12" bolts?

Do I use all new bolts (a $600 exercise for genuine head bolts priced from Don Kyatt), or if I am going all new, do I go the extra mile and splurge on ARP studs and nuts?

Thoughts?

Cheaper is obviously better as I'm not chasing stupid power out of the engine.

EDIT on the topic of head bolts, any suggestions for a good place to get Molybdenum Disulphide grease. The nearest thing the local Sprint store had was engine assembly lube "with moly-graphite". Loctite Moly Paste is probably ideal (65% MoS2), but none of the nearby auto stores seem to stock. United fasteners will be my next stop unless someone can suggest a place in the city or another suitable product.

Originally Posted by justinc

Youngest Daughter who is quite good at these things tells me that those are Kanji characters, and as she will be learning those next year at school (A HUGE amount of characters to learn, around 3000 IIRC!) she can't tell what they are about, so sorry can't help with dates

JC

the first and last columns are in kanji, 1st column（佐藤） is the name of the inspector, the last column（检查） means "inspected". I can't see the middle column after enlarging the picture, too blurry.

Just had a quick lool in a parts book, and Isuzu part numbers for head bolts look like:

4BD1
509009-0180 (14 required)
509009-0170 (4 required)

Early 4BD1T
894150-0250 (12 required)
894150-0230 (2 required)
894150-0240 (4 required)

Later 4BD1T
894367-4380 (12 required)
894367-4360 (2 required)
894367-4370 (4 required)

The quantity 2 bolts, are same size as the quantity 12, but have an integrated stud protruding from the hex head and they go at the front and rear of the head for a couple of accessory mounts.

I presume the later 4BD1T bolts are improved material or heat treatment, not different size, to overcome some issue found earlier.

I don't like the look of those stretched bolts

JIS (Japanese Industry Standards) for the numeral on the bolt head appears to be the same as the first part of the numeral on SI bolts, i.e. tensile strength of bolt material. The second part of SI property class, which starts from the decimal point is not a fraction of tensile strength.

So the 12 for a JIS bolt, I would take as the same as the 12, in a 12.9 SI bolt.

I replaced my head bolts with ARP studs some time back, so I can't check markings for the head bolts for my 4BD1T.

Originally Posted by Offender90

I'm aware it's ancient... but that's the way I like it! It complements both the 120's vintage and that of the git driving it reasonably well!

I thought it should be good for 200hp (may be pushing the friendship a bit, dunno?). It was roumored to have been designed for a 1.8L petrol, but fitted to a 2.2L petrol that made 175hp, developing 15psi boost from 2100 RPM onwards. I came across a few threads of people using it in diesels without reported adverse effects on VNT vanes fouling (my greatest concern), on both direct and indirect diesels.

My gut feel was that the turbine may be a touch restrictive for high power applications and was potentially contemplating leaving a provision for an external wastegate in the T3 to TK100 flange adapter, but am not sure it's worth the effort. Worst case scenario it'll be good for 180 HP with reasonable efficiency, which will still be more than sufficient to maintain my 110km/h and overtaking goals, but should see marked improvement in boost availability at lower engine speeds, which is where it will likely spend most of its time. I also like the simple VNT actuator control - it has potential for a simple boost controlled setup, with a in-cab regulated vacuum line for actuation point adjustment.

Time will tell how it behaves. I always have my T3 to fall back on if I'm unsatisfied.

To make 200hp you'll need to pull about 18 psi intercooled to 3000rpm. That's doable on that compressor, there are just others that will do it will less drive pressure.
My concern is whether that turbine can pass the exhaust flow.

I am currently running a T25 with the same compressor and turbine but not VNT and not intercooled, it has the 0.49 A/R wastegated turbine housing. I'm getting 10psi at 1200rpm and 20psi a bit before 2000rpm. With the wastegate clamped shut it the exhaust turbine chokes out about 2,400rpm and kills power.
I run a wastegate to get around that.

The VNT turbine can deliver more boost sooner (just in case you need that) and flow more volume through the same turbine as the rpm rise. You need that because you don't have a wastegate. Instead all the gas needs to exit through the turbine. The more pressure and heat you put on a turbine the more gas you can fit through it.
But the more pressure and heat, the more power they produce. Which produces more boost and this cycle does nothing but kill power once an engine is too big for the VNT turbo.

To hit 200hp you need to fit about 23 lb/min of exhaust through that turbine and you need about 25kw of shaft power.
The limit of a 0.49 A/R T25 turbine at 700C EGT and an expansion ratio to deliver that power is 23lb/min. The wastegate is basically shut and drive pressure is about 25psi.
The 0.64 A/R turbine according to the maps can't quite deliver. It can only produce 22kw from that pressure and flow with 20psi drive pressure.
The lower efficiency of the VNT (I'm using 0.55 vs 0.65 for the T25 turbines) means it needs cranked closed to a corrected flow of about 11 lb/min. This will spike the drive pressure to ~33psi.

However. I'm finding my actual results are giving better turbine performance than the predictions. Which to me suggests that exhaust pulse energy is driving the turbine harder than the published charts which are for steady flow.
I was certainly getting more than 17psi boost from the T25 0.64 A/R turbine with the wastegate clamped at 3000rpm. 2500-3000rpm was the operating point where the T2560 turbo that I built with the 0.64 housing was truely impressive.