LJ78 2LTE - Turbocharger Upgrade

GTSSportCoupe

2LTE abuser
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Mar 23, 2012
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Victoria, BC, Canada
 
Picked up a TD04L-13T turbo locally this weekend (originally from a 2006 Subaru WRX). I've upgraded many things on my engine (Intercooler/Intake/Exhaust/Cam/Tuning/Cooling/Emissions/Alcohol Injection, Etc.), but have never played around with different turbo chargers. Trying this thing out will be a winter project. I expect it'll be a vast improvement for the motor.

A lot of people think the CT20A is on the small size for the 2LTE. I feel differently. Little do most people know, in the last few years of the 2LTE, Toyota actually ran the CT9 turbo on it. This is a much smaller turbo, and probably actually maps better to the engine. Having talked to an LN165 owner (newer 2LTE with CT9), he liked the engine quite a bit, and said it spooled quickly. The turbine on the CT20A is actually quite big. In fact it's the same size as the one used on the 4.2l 24V 1HDFTE!! Both the CT20A and CT9 are old turbos with inefficient turbines however. I have pushed my CT20A to 19psi (post intercooler), and it has held up well. It keeps up even at high rpms and full load. However I think there are better options out there that will increase drive-ability of a 2LTE.

So what am I looking for in an upgrade? Well turbos have come a long ways since the late 80s and early 90s. New turbos offer quite a lot, and can transform the response of an engine. Here's what I'm hoping for:

- Lower intake air temperatures (more efficient compressor)
- Faster spool (more efficient turbine)
- Broader power band (boost achieved at lower rpm)
- Better fuel efficiency (my engine overfuels a bit until into boost; achieving boost earlier means a more efficient AFR).
- Possibly higher pressure ratios (I need to look at the compressor map for these again....), allowing for more fuel later if I want

Fortunately this version of the TD04 is clocked correctly for the 2LTE, and visually seems perfect for the motor There will still be some work in making it fit however:

- Custom machined manifold adapter (fab on the mill)
- Ebay dump pipe ($50 on Ebay)
- Custom oil drain pipe (maybe just bend the one on the turbo)
- Custom oil feed (buy a custom made hose)
- General purpose sections of rubber hose and clamps to connect coolant lines (any autoparts store)

I'll let you know how this project goes. These turbos are easy to come by (they cost in the $150-250 range), as many WRX owners upgrade to larger turbos. If this upgrade is successful, it could be an economical option for others who desire more performance/efficiency from their 2LTE. In fact you can probably flog your old CT20A for the same price or more...meaning this upgrade will be mostly just labor and some custom parts fab.

Here are a couple pictures of the turbo.

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GTSSportCoupe

2LTE abuser
Joined
Mar 23, 2012
Messages
6,280
Location
Victoria, BC, Canada
 
Haha, looking at those pictures I realize the wastegate actuator sits pretty high. That might one of the first challenges to deal with if it doesn't clear the hood.
 
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Chilliwack BC Canada
 
Following as usual!

I’ve actually completely disconnected my waste gate on my ct20a. Has to be perfect conditions for me to see over boost. I got sick of my cheap boost controller leaking oil everywhere.
 

GTSSportCoupe

2LTE abuser
Joined
Mar 23, 2012
Messages
6,280
Location
Victoria, BC, Canada
 
Following as usual!

I’ve actually completely disconnected my waste gate on my ct20a. Has to be perfect conditions for me to see over boost. I got sick of my cheap boost controller leaking oil everywhere.
Yeah, my MBC is turned all the way closed right now keeping the waste gate closed also.
 

GTSSportCoupe

2LTE abuser
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Mar 23, 2012
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Victoria, BC, Canada
 
Just looking into turbo specs a bit.... Note these are approximate numbers:

CT20A (1990 Toyota LJ78)
Compressor (ind/exd) Turbine (Ind/Exd)
39.6/57mm 60/44mm

TD04L-13T (2006 Subaru WRX turbo)
Compressor (ind/exd) Turbine (Ind/Exd)
40.3/56mm 47.2/41.1mm

Intercooled 2LTE maximum airflow requirement at 25psi/3500rpm comes out to around 320CFM or so using random online engine calculators. Same calculator at 25psi/2000rpm gives 180cfm.

13T Compressor Map (seems to match the engine ok to my untrained eye...). Looks like could run it up to around 24-25psi ok? Might get compressor surge at low rpm at these pressure ratios though? Will just have to try to know for sure. That said my CT20A has a similar compressor size and doesn't surge (audibly) unless I let off the throttle suddenly from 20psi.

m^3/s to CFM
0.05 = 106
0.1 = 212
0.15 = 318
0.20 = 423


 
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GTSSportCoupe

2LTE abuser
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Mar 23, 2012
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Victoria, BC, Canada
 
Apparently the 2LT-II injection pump maxes out at 120cc/1000strokes. I imagine the maximum capacity of the 2LTE pump is similar? Sort of adds up given the power I'm making right now. However is this enough fuel to spin the TD04L-13T up to 25psi?
 

GTSSportCoupe

2LTE abuser
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Victoria, BC, Canada
 
Another picture comparing the two turbos from when I was installing a new alternator this weekend. Note the picture is skewed making the TD04L-13T compressor housing look bigger than the CT20A's. However the TD04L-13T actually has a smaller compressor housing. The compressor inducer is almost identical in size though.

Was revving my motor a bit with the air intake pipe off the CT20A this weekend also. Put my hand near the compressor inlet (not too close!) to feel the air flow. As I let off the throttle I get a surge of air coming back out the CT20A compressor. Is this normal at low boost low rpm for turbos? Or does surge like this indicate the compressor is too big? @Dougal ?

I'm wondering if the 13T compressor is too large for a 2LTE....

IMG_20190914_094547670_HDR.jpg
 
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Not an engineer and don't know turbos that well, but it makes sense to me that while under throttle the turbo has charged the intake piping with compressed air, and then letting off the throttle, the turbo impeller can't hold back that compressed air and it reverses course briefly. Just a thought.
 

GTSSportCoupe

2LTE abuser
Joined
Mar 23, 2012
Messages
6,280
Location
Victoria, BC, Canada
 
Not an engineer and don't know turbos that well, but it makes sense to me that while under throttle the turbo has charged the intake piping with compressed air, and then letting off the throttle, the turbo impeller can't hold back that compressed air and it reverses course briefly. Just a thought.
Agreed, at very low turbo rpm it does make some sort of sense.

At higher turbo rpm and pressure, it's a bad thing and can damage the compressor. It's shown as the left most line on the graph above (surge line). When pressure is too high and air flow too low, the air can come backwards out the compressor. Makes a chuff chuff sound.... :oops: I can get that sound from my CT20A if I wind the motor up to full boost in a parking lot and then suddenly let my foot off the throttle....
 
Joined
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Medicine Hat, Alberta
I've been interested in the TD04 upgrade as well, but the idea of spending $$$$$ on a custom manifold puts me off. The adapter seems a better route. Where will you be getting yours?
 

GTSSportCoupe

2LTE abuser
Joined
Mar 23, 2012
Messages
6,280
Location
Victoria, BC, Canada
 
I've been interested in the TD04 upgrade as well, but the idea of spending $$$$$ on a custom manifold puts me off. The adapter seems a better route. Where will you be getting yours?
I plan to make one for the TD04. There are adapters available out there for CT20 to T25/T28. I have thought of trying a Garrett turbo instead of the TD04. Will see how it goes. I think a GT2052 would suit the motor well.
 
Joined
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Lynden, WA
Can't seem to beat the price on this v-band dump pipe. Thoughts?

Nick, I tried to do a V-band on my 2L-te to 2 1/2" downpipe when I upgraded the exhaust. I ran into trouble with not enough room to make it fit. Too close to the firewall. I actually had to cut off the V-band and weld it directly. Something to consider.
Jim
 

GTSSportCoupe

2LTE abuser
Joined
Mar 23, 2012
Messages
6,280
Location
Victoria, BC, Canada
 
Nick, I tried to do a V-band on my 2L-te to 2 1/2" downpipe when I upgraded the exhaust. I ran into trouble with not enough room to make it fit. Too close to the firewall. I actually had to cut off the V-band and weld it directly. Something to consider.
Jim
I was wondering about that; thanks very much! Well, I guess at the price of that unit; maybe I should just buy it anyhow, and cut/weld pipe on it.
 

GTSSportCoupe

2LTE abuser
Joined
Mar 23, 2012
Messages
6,280
Location
Victoria, BC, Canada
 
Hey Nick, Have you made any progress on this? I have found a decently priced TD04 in my area. Thinking about picking it up to swap one day.
Nope, have not got to it yet. And as @simonliew has said, they are popular turbos on the 3B's. Spool super fast.

I've gotten side tracked. Going to convert to manual hubs and do a front axle seal job at the same time. And going to switch to 80 series radius arms. After that I'm going to work on the turbo.
 
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