Thread: Another turbo question-- or 2

Originally Posted by 110Landy86

Hey Dougal you mentioned that you are running a T2560. Is that basically a bush-type variant of the GT2560R (being ball bearing)?? Would it be safe to say that a GT2560R (due to its internals) would be slightly more responsive at lower rev range compared to the T2560??

Also, you mention that the T2560 has "Lots more up top, it pulls strongly to my 3,600rpm rev limiter but I miss the low end." Is there a major difference between the T25 and the T2560 at lower end and which turbo do you think is better (subjective) based on your experience?

Thanks mate

Yes the turbo I've made is essentially a bushed GT2560R. The ball bearing versions should spin up a little quicker but they're not as durable long term as a bushing turbo. But this one I built from parts I had lying around as a cheap experiment.

The T25 was fantastic for low end boost, I could climb a hill at 1000rpm, plant the foot and it would build boost and pull away, I could pull 20psi at 1400rpm. But the tradeoff being about 2800rpm the power would taper off and past 3000rpm there wasn't much there.
With lower boost (15psi instead of 20psi) the T25 did an acceptable job through to the rev limiter, it was when asked to provide 20psi that the T25 got stressed.

I haven't had enough time to fully test the T2560. I've only done about 200km driving since and the rangie is currently parked up while I deal with some other projects.

The later Isuzu factory turbo is basically a wastegated T2554, I haven't tried that one myself but others here have. It's performance should be halfway between the two I've been tinkering with.

I recently purchased a brand new T25/T28 turbo including T2/T3 flange & hot side gaskets locally. Now in search of a suitable exhaust manifold...I can pick up a genuine isuzu 4BD1-T exhaust manifold with the turbo outlet set at ~35* sub-horizontal (as frequently pictured on here). They come out of Melbourne.

I decided to explore the used market and came across an exhaust manifold at available from a wreckers in Logan. The guy I spoke to said that it was off an 4BD1-T in an NP type light truck. The only difference was that the turbo outlet was horizontal/ 0* with the turbo mounting on top of the exhaust manifold.

Firstly has anyone come across these types of manifolds??? What are the pro's and con's with special emphasis on use of available engine compartment space albiet limited!!

The reason I ask is because, provided that there is sufficient clearance between the top of the turbo (mounted on a horizontal type manifold) and bonnet, then i think it might be a good alternative to others using the inclined turbo mounting that saves the OEM a/c unit all the while increasing the gap between the a/c unit and heat source.

Interested to know what you guys think

Cheers

Joe

G'day Joe
I have fitted this manifold with T2 flange. You are welcome to look at my set up (Wynnum). You will probably still not have room for the oem ac unit.
Regards
Peter

Joe i have the same manifold its the early IHI type i plan on using it as it only requires a small amount of elongation of the T25 exhaust housing bolt hols for it to fit and i my also face the exhaust outlet back towards the fire wall i havent tryed fit up yet tho i will be doing so in the next few weeks and i will post pics

Originally Posted by 110Landy86

I recently purchased a brand new T25/T28 turbo including T2/T3 flange & hot side gaskets locally. Now in search of a suitable exhaust manifold...I can pick up a genuine isuzu 4BD1-T exhaust manifold with the turbo outlet set at ~35* sub-horizontal (as frequently pictured on here). They come out of Melbourne.

I decided to explore the used market and came across an exhaust manifold at available from a wreckers in Logan. The guy I spoke to said that it was off an 4BD1-T in an NP type light truck. The only difference was that the turbo outlet was horizontal/ 0* with the turbo mounting on top of the exhaust manifold.

Firstly has anyone come across these types of manifolds??? What are the pro's and con's with special emphasis on use of available engine compartment space albiet limited!!

The reason I ask is because, provided that there is sufficient clearance between the top of the turbo (mounted on a horizontal type manifold) and bonnet, then i think it might be a good alternative to others using the inclined turbo mounting that saves the OEM a/c unit all the while increasing the gap between the a/c unit and heat source.

Interested to know what you guys think

Cheers

Joe

Joe

There are at least two different top mount manifolds. One has the IHI bolt pattern and a split port (you can see the divider inside the turbo mount flange), the other has the T2 flange and a clear oval port.

These manifolds are mostly found on industrial engines these days but were originally on the early (86-88) 4BD1T's with the IHI turbo. My engine is one of these but the manifold had the neck cut off and flipped when the previous owner installed the engine.

Thanks for the info guys

Also, Peter i'm interested in checking out your setup. Where can i find your write up?

I hate these threads. They remind me that I have a rebuilt T28 off a S14 200sx sitting in the shed. I keep reading, thinking how the extra power would help on the hills and would probably kill the LT85 to boot.

Must resist urge to needlessy tinker....

Joe
here are a few pics of my set up when it was new.