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50 Trim Turbos?????

3887 Views 18 Replies 2 Participants Last post by  umiami80
How is a regular old 50Trim Kit for the evo? I am looking long and hard at one.


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I was thinking about a 50 trim or a plain old 20g for a while. I finally got around to crunching some numbers on compressor maps and found that both had points just past the surge lines at 4500 RPM's and lower at 24 psi. But that's just me and the latest I'd want a turbo to reach full boost.
I used an old guide out of SCC, and maybe my math was a little off, but to me they didn't look appealing. Maybe if you go with a late spool/full boost at 5000 RPM or later it might work (.82A/R exhaust housing).
The power would be there at the high end, but as far as what's streetable and what's good spoolup; you make you own definition.
Here's the maps I used;
20g and big 16g (click on the check marks)
TO4E 50 Trim
I was very impressed with our big 16 map. The same numbers and 24 psi. was in the 68% efficency island with nothing past the surge line.
I'm not exactly sure what you said, But I know that a properly modded and tuned 50Trim would be at 20+ PSI around 3800RPM's. I am almost certain it'll spool just as fast as say a GT3071R and faster then the GT3076R and so on.
What do you mean by
both had points just past the surge lines at 4500 RPM's and lower at 24 psi

I figured that the 50Trim is the best pump gas turbo in terms of spool and power? :thumb:
I used 24 psi. and got a pressure ratio of 2.652 (left side of the map).
I plotted that against aginst corrected air flow (bottom of the map).
From the rough math I did, if this turbo reached the full boost of 24psi before 4500 RPM's, it would be surging. That's a bad thing. I'll do it over again tonight after work using 20psi and plot point some points.
So your looking for full boost by 3800 RPM's?
Your talking about the TO4E 50 Trim wheel too right?
Many people have run this turbo and have gotten it to fully spool (meaning 20+ PSI) under 4000 RPMS. In fact it probably spools the same as a GT3076R. I am not 100% sure of what you mean by surging, i always thought it meant that the turbo was providing more boost then the engine could handle at that moment? Or you mean compressor surge?

I am not entirerly sure what you are getting too but a properly tuned 50 Trim with a well designed tubular exhaust and an 02 eliminator and proper tunign will get you some very responsive and quick boost, certainly under 4000.
P.S. I am looking at the 50Trim offered by RnR. What I do know is that 24PSI by 4500 RPM's is what a GT35R spools by and a properly tuned 50 trim would CERTAINLY spool faster then that.
OK, I looked at RnR really quick and I'm kinda confused about what wheel they use;
Is it the TO4E 50 trim wheel or the T3 50 trim wheel. I think I better learn more about T3/T4 hybrids. The map does look way better for the T3 50 trim;
I am ALMOST certain it is the T3. Hybrids kick ass man, all you need as far as pump gas is concerned. This turbo can and has made 420WHP (Dynojet) and run mid 11's at about 122-123MPH, all I need man. It'll make 500WHP on 30PSI for sure. :) This may be the ultimate turbo as far as the 2.0 4G63 is concerned. Defenately considering the price.

Why not do some dective work for me? :thumb:

BTW this 50 Trim flows 49LBS of air, I know that. The GT3071R actually flows less. The GT3076R flows 52pounds.
umiami80 said:
Why not do some dective work for me? :thumb:
BTW this 50 Trim flows 49LBS of air, I know that. The GT3071R actually flows less. The GT3076R flows 52pounds.

I'm on it. I'd be alot easier if my wife didn't throw away my last calulations. :cry:
Just looking at both the big 16g map and the t350 trim there's a lot of over lay, but the t3 has more in the 70%+ islands.
Don't forget that the 50Trim EASILLY makes over 400WHP on pump gas, can't do that on the 16G.
Well I have decided to go with an RnR 50trim. I am STEALING one, theft as it may as well me one in teh same. It truely is a street turbo and will make more power then a 3076R on PUMP GAS, although this thing also makes 500WHP on race gas with a stock inatek manifold and head somehow.

Also, the GT3076R option is $600 more, meh too much.
I am, also looking for an EGT gauge, may as well go for EGT while I am at it :)

Looking for a Cheap 45MM EGT gauge.
Finally did the math for the T3 50 trim;

At 20 psi and assuming a 1psi. pressure drop across the intercooler I got a pressure ratio of 2.41
For corrected mass flow rates I got (assuming 90% efficency);
33.47 lbs/min @ 7000 RPM's
28.68 lbs/min @ 6000 RPM's
23.90 lbs/min @ 5000 RPM's

Plotted on the above map;
If the peak boost of 20psi. hits at 5K, it's in the 70% island. :thumb:
20 psi. at 6k is just off the 65% island. :|
20 psi. at 7K (redline) is off the map = inefficent/blowing hot air. :thumbdown

The same points (same 20psi.) do look better back on the TO4E 50 trim (see the map in earier post);
Peak boost by 5K is just inside the surge line in the 72% island (could get away a little earlier with antisurge ports). :thumb:
20 psi at 6K is in the 76% island. :thumb:
20 psi at 7K (redline) is in the 78% island. Nice cool boost up top. :thumb:
Again this is only at 20 psi.
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To tell you the truth I have no idea which one it is. It may be the T4 and I am thinking it has too. It makes 420WHP on pump gas at around 20PSI. It makes over 500WHP on pump, it is right there with a GT3076R but a lil smaller and does achieve full boost around 4000, maybe it's in the manifold design? IDK, I will post results but From what I HEAR, for the money this is teh ultimate pump gas turbo. The turbo it makes is just sick compaired to its spool and torque band.
Well I just found the Kit I am getting, here are the specs, ready?

The Turbo is

T3/T40E Turbo

It includes this.

T3/T40E Turbo
304 SS cast 8 gauge manifold
Ram Horn Equal Length Style Manifold
Jet Hot coated manifold
3" SS 02 Elim Downpipe(bolts up to 3" flange)
Tial 38mm Wastgate
SS Dump Tube
2.5" SS304 Lower IC pipe w/silicon hoses and t-bolt clamps
AN fittings
SS oil lines
coolant lines
SS bolts, nuts, washers, etc
SS gaskets
hose connectors
Everything needed to bolt-on to your car!

Looks like this.

I can't think of a prettier manifold.
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Also, what does it mean by 78% efficient and so on? Thanks, gimy some of that info. I just know which turbo will work on a Evo well :)
umiami80 said:
Also, what does it mean by 78% efficient and so on? Thanks, gimy some of that info. I just know which turbo will work on a Evo well :)

Contact RNR and find out what specific compressor wheel they use.
The greater the efficincy, the cooler the air coming out the turbo. That's a good thing. If your lokking at a map and getting points out of the efficency range, the turbo is just blowing hot air and you not going to make power.
So I see efficiency range like 78%, I see it increase with boost I would immagine it would decrease as boost rises. So is there such thing as 100% :) What is the percentage a measure of?

Anyway I am buying thye kit and will post my install and then Dyno numbers later on.
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