4BD1T Turbo Sizing and Performance Prediction.

**Dougal** · 16th October 2013, 01:03 PM

Okay guys, I think I've cracked it for the HE221 and TD04HL.

Here's what I did.
1. I downloaded a QSB4.5 CAD model a while back. This had an outside surface model of an HE221 turbo. I'm assuming this turbo has the 6cm housing.
2. I cut the turbo CAD model parrallel to the exhaust flange at shaft height.
3. I assumed the walls of the scroll were about 4mm thick, so I offset the outer edges and made a shape to resemble the port.
4. I adjusted the width of this port to give an area of 6cm^2.
5. I measured on the computer the distance from the port shape I'd just created to the centreline of where the shaft would be.
6. Divided A by R and converted to inches.

Now it's not 100% because I've had to assume two things.
1. The shape of the port and wall thickness I had to make up.
2. That the model I had was a 6cm housing.

The results come out with 6cm area and 4.9cm radius. A/R is 1.22cm or 0.48 inches.

This was the second attempt. The first one I used a 5mm wall thickness and due to the changes in port shape that gave a result of 0.51 inch A/R.

So it's not exact, but I'm pretty damn sure I'm within 10%.

Now here is the interesting part that I'm sure turbo makers really hate me doing.
I've collected all the turbine flow figures from the garrett turbine maps and arranged them all in a table with exducer size, A/R and max corrected flow.
I've thrown the Borg Warner EFR turbine maps for the EFR6255 and EFR6258 in there for good measure.
I've found a quite common relationship across all of them.

A/R doesn't change the flow linearly, it's a square root relationship. So if you half the A/R you change the max flow by about the square root of half or 0.7.
If I divide the exducer flow area by the square root of the A/R I get a consistent number across all turbines of similar size.
As the turbines get much larger, this number drifts a bit smaller. But the trend is very good and easy to follow.

Upshot. I can predict max flow and the rough shape of a turbine map from the turbine exducer and the housing A/R.

So for the HE221 or TD04HL with a 6cm housing (same thing) we have an exducer of 45.6mm and an A/R of 0.5.
The max corrected flow is expected to be ~14.7 lb/min which is just a fraction bigger than the Garrett GT22 (14.2lb/min), significantly bigger than the 0.49 A/R T25 I'm running now (approx 13.3 lb/min). But approx 10% smaller than the 0.64 A/R T25/T28 I had run for a while.
In short, it is the size I hoped it would be.

This also lets me work out the max power and hence max boost/flow this turbine can support.
Using EGT of 700C (1300F), backpressure of 120kPa (3psi) and a pressure ratio of 3 we have a real turbine flow of ~28.4 lb/min, drive pressure of 37.5psi and turbine power of 41.5kw.
The temperature drop across the turbine is 192C.
This 41.5kw of turbine power can drive 29psi of boost to 4000rpm on a 4BD1T. It reaches right to the top and right of the HE221 and TD04HL-19T compressor maps, which is a good sign that the numbers are close to correct.
This amount of boost could deliver approximately 207kw at 4000rpm on a 4BD1T.

**Dougal** · 17th October 2013, 07:34 AM

One helpful gentleman from Norway tells me the HE221 has a 1mm bigger turbine exducer than widely reported on the interweb. Everyone thought it had the same turbine wheel as the TD04HL, but it's machined to a slightly bigger trim number.
So crunching those numbers, the HE221 comes out at ~5% more turbine flow than the TD04HL. Which makes the TD04HL the quicker spooler and harder boost down low of the two.

It's a pretty small difference, the TD04HL should hit the same boost about 100rpm sooner.
The tradeoff is the TD04HL would take about 2psi more drive pressure at maximum pressure and flow.

**Judo** · 17th October 2013, 02:35 PM

Outstanding work Dougal. I completely forgot to ask if you wanted any measurements of my TD04HL-19T? Last night I bolted it to the manifold for final fitting with copper gasket spray, but I could still easily remove it if there is anything useful to gain.

BTW, I already know how easy it is to remove and clean the copper spray. After fitting it, I realised I'd left a rag inside the exhaust manifold.

At least I remembered! haha. If anyone is interested, methylated spirits is excellent for cleaning copper gasket maker off a flange.

Anyway, let me know.

**Dougal** · 17th October 2013, 02:57 PM

Originally Posted by Judo

Outstanding work Dougal. I completely forgot to ask if you wanted any measurements of my TD04HL-19T? Last night I bolted it to the manifold for final fitting with copper gasket spray, but I could still easily remove it if there is anything useful to gain.

BTW, I already know how easy it is to remove and clean the copper spray. After fitting it, I realised I'd left a rag inside the exhaust manifold.

At least I remembered! haha. If anyone is interested, methylated spirits is excellent for cleaning copper gasket maker off a flange.

Anyway, let me know.

Thanks Justin but I think I'm good for now. Remembering I had that CAD model was a complete game changer.
How far are you away from running? A lot of people have bought TD04HL-19T's for 4BD1T's, but AFAIK none of them are yet running.

**Judo** · 17th October 2013, 03:10 PM

I put the battery on trickle charge last week in preparation. I keep thinking I have everything I need, but every Saturday for the last 3 weeks I end up at Enzed for something new. The different plumbing pressure threads and fittings are doing my head in! Already planning another trip this Saturday for another adapter I need for the oil feed from the block.

BUT there is a chance I'll turn the key this weekend. Then I need an exhaust. Will book it in to an exhaust shop the day it runs. Is it optimistic to think I can drive it a few kms (metro Melbourne) without any dump pipe?

**Dougal** · 17th October 2013, 03:13 PM

Originally Posted by Judo

I put the battery on trickle charge last week in preparation. I keep thinking I have everything I need, but every Saturday for the last 3 weeks I end up at Enzed for something new. The different plumbing pressure threads and fittings are doing my head in! Already planning another trip this Saturday for another adapter I need for the oil feed from the block.

BUT there is a chance I'll turn the key this weekend. Then I need an exhaust. Will book it in to an exhaust shop the day it runs. Is it optimistic to think I can drive it a few kms (metro Melbourne) without any dump pipe?

We all know that feeling.
I've driven my 4BD1T with no turbo. That was an ear-muffs required experience. With an open turbo it won't be as bad, but EVERYONE will know what you're doing.

Yes Mr Officer my exhaust fell off, I'm driving to the exhaust shop to get a new one. Feel free to escort me there.

**steveG** · 17th October 2013, 09:33 PM

I've driven mine with just the dump pipe finishing at the gearbox cross member. Noise was less than half the commodores that drive past my office each day.
Bigger issue with no dump pipe at all would be hot exhaust gas on the back of the alternator. I'd at least try and arrange some sort of deflector to protect that.

Steve

**jackz** · 19th October 2013, 08:16 PM

Originally Posted by Dougal

Thanks Justin but I think I'm good for now. Remembering I had that CAD model was a complete game changer.
How far are you away from running? A lot of people have bought TD04HL-19T's for 4BD1T's, but AFAIK none of them are yet running.

I'm still collecting parts to do my conversion, being my daily driver, I need to get as much stuff as possible together, and then pull a week or so of sickies (

) to get it done.

**Jitterbug** · 22nd October 2013, 10:14 AM

BW EFR 6258 ordered...

This will be going on an a reconditioned early 90s 4BD1-T and intercooled with a front mount Air-to-air.

I will update the details in my '6x6 camper thread' in members rides.

**Dougal** · 22nd October 2013, 10:47 AM

Originally Posted by Jitterbug

BW EFR 6258 ordered...

This will be going on an a reconditioned early 90s 4BD1-T and intercooled with a front mount Air-to-air.

I will update the details in my '6x6 camper thread' in members rides.

Just so you know. You'll get significantly more low end boost from a TD04HL-19T. The EFR has a turbine that's a far bit larger.
The EFR will have the edge for top end power though.

Thread: 4BD1T Turbo Sizing and Performance Prediction.

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