Thread: Turbos that work on a 4BD1.

Originally Posted by Lotz-A-Landies

I thought that a smaller turbine wheel spins up more quickly but runs out of boost where a large wheel has a large turbo lag or something.

But you seem to be suggesting it doesn't matter?

This doesn't help with an original purchase, when there are so many turbos that would fit the same flange and vehicle eg T3 on Nissan RB20

That is right, smaller turbines spin up faster but choke off the top end. But you need to consider the combination of wheels and housings.
You also need the hot and cold sides reasonably well matched, there is no point in having a huge compressor if the turbine will choke the engine before it can use all the air flow.

For re-using turbos, those factory fitted to 1.8-2 litre petrols are generally suitable for up to 15psi on our engines.

Originally Posted by Lotz-A-Landies

OK when we talk about compressor/turbine wheels which would be preferred and why?

.50 A/R Compressor, .63A/R Turbine
.58 A/R compressor, .50A/R Turbine

and why?

With a particular size turbo core, the turbo can be matched to, or tuned for, a range of engines or powers by changes to turbine housing or compressor wheels and covers.

On the turbine side, changing A/R of the housing is most effective. Reduce A/R if it is required to spin up faster, or increase A/R if it is chocking. Swapping the housing is simple bolt on, and you will find the manufacturer has a range of housings to choose from.

On the compressor side, A/R doesn't make much difference, instead the wheel and cover are changed.

In my last post I should have also said that compressor trim is a usual procedure for tuning the compressor side.

Hi guys, I am a newbie to the forum. I have a 1984 120 tray with the Isuzu motor owned from new. I am thinking about turboing it for general use as my children think it is too sluggish!! Would love any information on the best way to go about doing this, keeping in mind reliability and life expectancy are my main priorities. I dont need anything with huge PSI boost, just something that will increase my power out on the road.

Also would like to know anyone's thoughts on air to water intercoolers?

Many thanks in advance, Mark.

there is numerous threads on here but for ease of installation and easy to find i would personally go what isuzurover has done as they are a more common turbo and as isuzurover has stated they are a good turbo for highway use.
when you say big boost dont think like that because thats what concerns petrol boys not so much diesel boys.you will find most people are running over 12psi which is fairly high for petrol motors (apart form some such as my mates offenhauser running 32psi)

cheers

Originally Posted by Lotz-A-Landies

OK when we talk about compressor/turbine wheels which would be preferred and why?

.50 A/R Compressor, .63A/R Turbine
.58 A/R compressor, .50A/R Turbine

and why?

Just saw this post again and realised that in my previous reply I should have pointed out that A/R has to do with the cross sectional area ('A') of the air/gas inlet passage in the turbine housing or outlet of the compressor cover, divided by the radius ('R') of the centroid of that area to the rotational axis of the turbine/compressor.

A/R is not a value of either the turbine or compressor wheel (impeller).

Impeller measurements of main interest are:
Inducer (inlet) diameter - wheel outside diameter in the case of the turbine
Exducer (outlet) diameter - wheel outside diameter in the case of the compressor
For compressors (but not turbines) the trim is also of interest as it affects efficiency. Trim relates the areas of the inducer and exducer as a percentage, but when trim is expressed mathematically, pi cancells out so we are are left with just inducer and exducer diameters squared.

Hi John

Sorry a long time away from this thread. Once upon a time, I thought I was smart, but maths always does my head in as my thoughts accellerate off at tangents to the focus of the issue!

In my limited experience of this issue, I was under the understanding that manufacturers are getting better/more efficient results by modifying the shape of the turbine vanes rather than the crude calculation based upon A/R or are you suggesting that the A/R actually calculates the vane design?

And

How can one determine the efficiency of a particular design?

Wouldn't it be good if we could merely punch in some parameters like flange, engine capacity, vehicle weight and RPM band into a calculator and the result would come out as a part number including the vendor with today's best price!

Diana

Hello.