Query on setting up turbo on NA 4BD1

**justinc** · 9th November 2008, 10:40 AM

Hi Glen,

I have had great success with my installation, it is in a 1992 RRC, LT95 box and 33's. Matt(Rovercare) and I both have the same turbos 'kits'etc from Turboglide, and we are both using front mounted intercoolers.
The efficiency of having an IC when boosting above 10psi or thereabouts is better, Less smoke and lower EGT's.
I'm getting around 12litres/100km around town, and 15l/100 towing a camper trailer at 100km/h. At these hiway speeds on a flat road, my upstream mounted pyro measures around 350deg, and up to 450deg if into a headwind. When pushed to the governor up hills etc, it will peak at 550deg.

I have 15psi on full noise at the manifold, I have disconnected the wastegate and have set it up using the fuelling to control max boost. With the .48A/R housing I am getting almost zero lag, and have wheelspin/ traction issues when climbing hills around corners on dry bitumen even under moderate throttle use

No Dyno figures yet, I'm working on it!

IMHO these engines are overengineered in a TRUCK, so turboing a N/A engine in a RR or 110 etc is chickenfeed for this iconic Isuzu engine

In trucks, at a MUCH higher duty cycle, these engines are good for a million K's. I'm hoping for at least that from mine, as it now has about 550k up and shows no signs of stopping

It initially came from a 1988 110 that fell apart from rust at 420K, the engine outlasting the vehicle. I DO take care of it, oil and filters regularly, shut down ONLY sub 180deg temps, and I DON'T let it idle all the time.

In Short, it is very hard for you to hurt one of these engines

JC

**isuzurover** · 10th November 2008, 02:08 PM

Originally Posted by rijidij

The 4BD1T that I fitted came from a truck and the turbo only boosts to 9psi max according to my gauge. I was led to believe that standard boost was even less than 9psi, so I have'nt 'played' with it. 16/17psi sounds more appealing. Are these figures mentioned in an engine manual anywhere ? I would like to try more boost, but one of my main aims is to get a long life out of my engine.

It's interesting to see that a company like Turbo-Glide set their turbo kits to 9psi.........

Q. How much boost and power do you set up for along with Max EGT?

A. We use 9lb and a torque gain of no more than 30% and an EGT of no more than 500°Celcius under prolonged full throttle usage. My staff and I have seen many turbo kits installed exceeding these parameters resulting in severe engine damage. Use of chassis dyno is mandatory before and after fitment of turbo.

Turbo-Glide: Turbo FAQs

Sorry - 16/17 is Tdi spec... Getting the numbers mixed up. This is what I posted earlier - taken from my isuzu WS manual:

Originally Posted by isuzurover

A few people have asked about this in the past and I think there has been a bit of misinformation (some may have come from me

).

I finally got my ISUZU WS manual back in my hands, and it says:

1988 and Earlier engines were fitted with an:
IHI RHB-6 (with wastegate). The wastegate opening pressure (boost pressure) was: 680mmHg = 13.15 psi = 0.91 Bar

1989 and Later engines were fitted with a Garrett T-25 with NO WASTEGATE. Maybe this is where the erroneous 5psi boost figure came from, but I don't see why these would run lower boost than the earlier engines.

Murray - which turbo do you have?

**rijidij** · 10th November 2008, 07:36 PM

Originally Posted by isuzurover

Murray - which turbo do you have?

This is the tag off my turbo. The engine came from a 1988 NPR59, and it does have a waste gate. I haven't really got into the turbo side of things yet, because I haven't had to, but if there is more potential there for more performance without over doing things I would like to investigate it more.
If anyone can give me more info about my turbo from the numbers on this tag I would appreciate it. I presume TF 0424J is the model.

**isuzurover** · 10th November 2008, 11:05 PM

Originally Posted by rijidij

This is the tag off my turbo. The engine came from a 1988 NPR59, and it does have a waste gate. I haven't really got into the turbo side of things yet, because I haven't had to, but if there is more potential there for more performance without over doing things I would like to investigate it more.
If anyone can give me more info about my turbo from the numbers on this tag I would appreciate it. I presume TF 0424J is the model.

You can plug those numbers into the garrett/honeywell website and they will give you the specs.

My manual was published Sept 1988. I think some people have said that the IHI-turboed engines never came here.

**Dougal** · 11th November 2008, 05:00 AM

Originally Posted by rijidij

This is the tag off my turbo. The engine came from a 1988 NPR59, and it does have a waste gate. I haven't really got into the turbo side of things yet, because I haven't had to, but if there is more potential there for more performance without over doing things I would like to investigate it more.
If anyone can give me more info about my turbo from the numbers on this tag I would appreciate it. I presume TF 0424J is the model.

That'd be the rare wastegated T25.

I have a non-wasteged T25 from a 4BD2T in my parts bin. Garrett #466898-6
Here's the wastegated T25 from a 4BD2T from a guy in the US Garrett #466409-1
Both of these fit the T3 flanged manifold like Isuzurover has used in his conversion.

Which manifold do you have Murray?

**justinc** · 11th November 2008, 06:07 AM

Originally Posted by Dougal

That'd be the rare wastegated T25.

I have a non-wasteged T25 from a 4BD2T in my parts bin. Garrett #466898-6
Here's the wastegated T25 from a 4BD2T from a guy in the US Garrett #466409-1
Both of these fit the T3 flanged manifold like Isuzurover has used in his conversion.

Which manifold do you have Murray?

Said in your best 'David Attenborough' voice

JC

**rijidij** · 14th November 2008, 08:31 PM

Originally Posted by Dougal

Which manifold do you have Murray?

I don't know how much you can tell from these pics.

**Dougal** · 15th November 2008, 06:42 AM

Originally Posted by rijidij

I don't know how much you can tell from these pics.

That's the latest style manifold, the same one that Isuzurover bought and fitted his turbo to.
It has the T3 flange, but I have adapters to fit T25/T28s on them (Isuzurover is running one).

Is that a wastegated turbo? It'll have an actuator can with the rod running to a lever underneath the exhaust outlet if it is.

**rijidij** · 15th November 2008, 11:47 AM

Originally Posted by Dougal

Is that a wastegated turbo? It'll have an actuator can with the rod running to a lever underneath the exhaust outlet if it is

Yep, it is wastegated. 9psi is the max it goes to. I have'nt touched the turbo except for spinning the compressor housing around.

What are you referring to with these figures......

A/R 0.48 on the turbine and 0.42 on the compressor

If I want to fit a turbo to my 120 NA, is there a particular model I should look out for, eg T25, T28 etc etc and I presume each model comes in differing specs ?

The Mutt · 16th November 2008, 05:57 AM

Where is the best spot to hook up a boost gauge?

I'm putting the EGT probe into the exhaust today, and am looking at getting a boost gauge next.

Glenn

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