Thread: 4BD1T Turbo Sizing and Performance Prediction.

Originally Posted by isuzutoo-eh

Does it count if the turbo is in a box o nthe back seat?

Originally Posted by flagg

haha yes. I can't complain, mine sat in a box in the garage for over a year before I bolted it on!

In that case I can come with twin turbos. One up front and one in the back (seat).


Dougal will be asking for a clean up of his thread soon.

Originally Posted by Judo

I haven't tried to correct the inlet pressure on that graph but the 20C matches Dougal's 4bd1 PR vs flow graph, so that doesn't need correcting...right?

I found the conversion between m^3/s and lb/min and I'm confident (never 100%) I got that right when overlaying the graphs. However I tried to do the same with the IC graph and failed. The scales were all wrong or something. I will try again and post up results once I think it's correct.

I have plenty of motivation to fix these graphs now. I ordered one.

Kinugawa Turbocharger TD04HL-19T / T25 Flange / 6cm Oil-Cooled.

I did some google searching and learnt a few things:

1. The brand has mostly excellent reviews. As good as you would expect from random Internet reviews/forums.
2. It's possible they might be rebranded Kamak's? KAMAK DYNAMICS - Distributors - Asia
3. Kinugawa have Australian bank details if you prefer this to an ebay purchase...
4. You guys post on a lot of forums. Not sure if I'm the first on here to order a Kinugawa, but there looks to be a lot of recent purchases on 4btswaps for trials as well. Can't wait to see how it goes!

Very keen to see how this goes, I nearly pulled the trigger on a BW turbo but then decided to hold off, then the AUD dropped, now I am questioning the need to go for the expensive option when I am not chasing big numbers. Comments on quality etc when you get it would be appreciated.

Originally Posted by Dougal

Latest effort.
Borg Warner EFR6255 (smallest in the EFR range) on a 4BD1T with a maxed out pump and intercooler at 3,600rpm using very safe A/F and EGT. Should be good for about 280hp. Possibly more as I've used conservative figures: BorgWarner MatchBot

Apparently the Borg Warner EFR6255 isn't available. I'm guessing demand wasn't high enough so they dropped it. Smallest one is the EFR6258 which Flagg has used.
The difference is relatively minor, but the 55 would be a bit faster spooling. Same compressor on them both.

Originally Posted by Jitterbug

Very keen to see how this goes, I nearly pulled the trigger on a BW turbo but then decided to hold off, then the AUD dropped, now I am questioning the need to go for the expensive option when I am not chasing big numbers. Comments on quality etc when you get it would be appreciated.

I will certainly be posting all my stories as they are available.

Note the AUD affects the Kinugawa turbo prices too. The same one I bought on ebay was $100 cheaper a few weeks ago. When I messaged the seller about it, he apologised but said it was the exchange rate that caused the price jump, not his own price rise.

If you want to go real cheap (quality unknown?), this is a straight T3 bolt up (I was very tempted). But if you can see a brand name anywhere on that turbo, you're doing better than I! IMO Kinugawa is already ahead being that they have a name.

Isuzu Truck NPR 4DB2 4BD2 TB2568 Turbo Turbocharger 466409 0002 8971056180 | eBay

My source: http://www.aulro.com/afvb/isuzu-land...ml#post1714096

Originally Posted by Judo

I will certainly be posting all my stories as they are available.

Note the AUD affects the Kinugawa turbo prices too. The same one I bought on ebay was $100 cheaper a few weeks ago. When I messaged the seller about it, he apologised but said it was the exchange rate that caused the price jump, not his own price rise.

If you want to go real cheap (quality unknown?), this is a straight T3 bolt up (I was very tempted). But if you can see a brand name anywhere on that turbo, you're doing better than I! IMO Kinugawa is already ahead being that they have a name.

Isuzu Truck NPR 4DB2 4BD2 TB2568 Turbo Turbocharger 466409 0002 8971056180 | eBay

My source: http://www.aulro.com/afvb/isuzu-land...ml#post1714096

The TB2568 (4BD2T turbo) is the best of the stock turbos. But the TD04HL-19T should deliver a lot more low end boost and more boost. The TD04HL-19T can do 30psi to the rev limit, the TB2568 shouldn't.

The EFR 6258 has also gone up in price quite a bit since I ordered mine (in USD, not just the exchange rate). Apparently there were some manufacturing issues that caused delays and I guess the price increases.

So I've finally had some time to crack the turbine sizing thing. Borg Warner use a number called Phi on their turbine maps:


Garrett use "corrected mass flow" for theirs:


So here is how they work. Turbine power is essentially an arc centred around the lower left hand corner. So if you need say 20kw of turbine power, you'll have an arc which cuts that chart from top left to mid right.
Where that 20kw arc cuts the red line is where the turbine can provide that amount of power.

Every turbine like that has a lower limit where it can't get enough flow to start working and an upper limit where it's choked out and can't produce any more power. In between how much power it can produce depends on how efficient it is.

The crux of all of this.
The Borg Warner EFR6258 turbine starts at about the point of a Garrett GT28 turbine with a 0.64 A/R housing on it.
The difference is, the EFR is a lot more efficient so requires less drive pressure to produce the same turbine power.

Here is the GT2871 turbine map, max efficiency about 68%:


Here is the matchbot stock figures showing 75-70%:
BorgWarner MatchBot

This is why Borg Warner can get away with a larger turbine. The larger but more efficient turbines used on the Borg Warners can ultimately support more power for higher boost at higher rpm. But that said, even the T25 turbine can deliver backpressure below boost for the lions share of it's full load operation and can still provide enough boost to max out a standard pump.
At 750C EGT I'm getting 32psi drive pressure to produce 25psi boost at 3,500rpm with the 0.49 A/R T25 turbine. That's just over 33kw turbine power which is enough to feed 180kw of engine power.

I'm still crunching all these numbers, so don't get too excited yet. I also haven't visited the Garrett GTX range which should offer some competition to the BW EFR series.

Do you have any fuel screw left for those figures Dougal?