Turbocharger Size for Optra/Forenza/Nubira??

OptraSS · Post by **OptraSS** » Sat Sep 11, 2004 4:11 pm

I am intersted in adding a F/I kit on my 2004 Optra. I am wondering what size of turbocharger I should go with?? T25, T3/4?? what would be efficient for the 2.0litre engine? I will be looking to run around 160-200WHP.

thanks for the help.

Tom

richardmatalon · Post by **richardmatalon** » Sat Sep 11, 2004 6:12 pm

When It comes to turbos, I am a firm beleiver in the bigger the compressor housing the better. Now, The backhousing should be somewhat small beucase it is what will give you lag, but the bigger the compressor housing, the more air you can flow on less boost. I would go with either a garret t3 or a t3/t4. I think the t25 might be a bit too small, but others may disagree. It is what was used on the sohc 8valve turbo model of our engines but remember they were sohc, and only 8vavle, so our heads will flow more air, allowing for a little bigger turbo. The t3 is what I am going to use on my nubira and I think that I should be getting full bost (about 8psi at first) from about 23-2500 rpm. THe bigger the rubo, the more effecient the turbo will be becuase the air will be cooler becuase you can run the same amount of power on less psi of boost jsut becuase it will flow more air and the turbo will have to work less to make the power. Well this is just my 2 cents.

Post by **PrecisionBoost** » Sun Sep 12, 2004 1:49 am

The T25 is perfect for this engine if your looking for 175whp ( roughly 200hp at the crank)

The T28 is needed beyond that.... or a hybrid like GsiTurbo's setup... I think it's a T25/T28 but I'm not 100% sure.

I'm trying to remember which turbo was used on the 205hp C20LET ( 16V Turbo ) I don't know if it was a T25 or a T28

This head was designed by Cosworth and it is far superior compared to the stock Nubira head.

I personally like the Garret GT28RS turbo.... it really kicks ass.

By the way.... I have to wonder about the T3 spooling up that quick... I wouldn't be surprised if it doesn't spool until closer to 3000RPM.

Bigger turbos are not necissarily more efficent.... you have to do the calculations with the turbo's compressor map to figure out your efficency for each type of compressor.... even between different models ot T3.

I think there was a post with information on the turbo map calculations... if you do some digging I'm sure you will find it.

OptraSS · Post by **OptraSS** » Sun Sep 12, 2004 2:15 am

Thanks for the info, much appreciated

. A buddy of mine has an acura 1.6EL running a T4 turbo, but that sucker doesnt get full compression till about 4500rpm, but he drag races it. I am more of a winding road type of guy and i like to have power on demand. I think anything from 160-200whp would be perfect.

i'll probably end up gettin a t25 or t28

thanks again

Tom

GsiTurbo · Post by **GsiTurbo** » Sat Sep 18, 2004 6:37 am

Sizing your turbo is a little bit more than just stating "I like the T3".

Every turbo has its own specific efficiency, which is maximum at only certain area of rpm and/or boost. You should decide what is the boost you want to run, if this is temporary or if you will want more later. Then, a set of calculations need to be performed to determine what kind of efficiency your turbo will have throuout the powerband. You may find out, for example, that you will have decent efficiency only in the last 1500rpm or so, and b4 that, you might be way out. This would not make a good streetable turbo.

So, ask yourself this question:

- how much boost am I going to run?
- how much boost will I run 6 months after the install?
- how much horsepower do I want to make?

mocpac · Post by **mocpac** » Sat Sep 18, 2004 9:53 pm

t3 is to big you will have tubo lag until you reach the 3k rpm

debo890 · Post by **debo890** » Sun Sep 19, 2004 3:10 pm

not true. my nubira gets into boost by 2500 rpm and full boost by 3000 rpm. it depends on the load you car is on at the time. sometimes i get full boost at 2500 rpm. setup: t3 a/r: 48/60 (ford mustang or mekur turbo) tial wastegate @ 5psi, vortech boost dependant regulator, 90-92 integra aftermarker check valve, xs blow-off valve, apex II safc, stock manifold (turbo welded to the top flange of first cat-converter). engine not yet tunned or dynoed but it feels like 170-180 hp. when tunned i'll increase boost to 7 psi for 200hp goal on stock internals(waiting for gsi turbo to get back to me on the forged pistons for the nibi. then i'll go mad boosting to high levels). i can smell my clutch smelling like bunt rubber so i need a better street clutch( but from were in the usa?

). anyway, go with the t3 if you plan on increasing the boost later on. OUT...

Post by **PrecisionBoost** » Sun Sep 19, 2004 7:16 pm

There are so many different setups for the T3 and T4 so the spool up characteristics would be different for each one.

What size of engine did the mekur turbo have?

It sounds like you have a decent setup if you can start getting full boost by 2500 to 3000RPM

GsiTurbo · Post by **GsiTurbo** » Sun Sep 19, 2004 8:25 pm

The Merkur (aka Ford Sierra, US version of Sierra Cosworth), was based on the 2.3 Ford 0HC 8V engine, used previously in the N/A Ford Mustang.

It featured an Air Research T3 turbocharger, and 8:1 compression ratio. This boosted the engine output to 170hp@5200rpm, and max torque of 264lbs @ 3800rpm.

It was using cast iron block and the cylinder head. Bore ? stroke 96.00mm ? 79.20mm
0-60mph in 7s, standing 1/4mile 15.5@90mph stock.

mocpac · Post by **mocpac** » Mon Sep 20, 2004 8:09 pm

Yes! bebo890 must habe one of the best set ups in a stock nubira to get that.

Give me your settings and part that you use to get that power.

debo890 · Post by **debo890** » Tue Sep 21, 2004 7:09 am

my setup is:
turbo:

Ford Merkur XR4TI(us), turbine/compressor, 48/60
2.5 in downpipe all the way to the muffler.
single cat. second o2 sensor moved behind second o2 sensor.
stock manifold modified with a wastegate in the center.
cut first cat. top flange and weld to turbo for almost stock apperence.

engine:

removed map sensor and put a hose fitting into it's port. ran a hose from it to the map sensor with a missing link check valve(90-93 Integra B18 part#ML002B)

vortech 12:1 rrfpr
stock injectors
apexi safc II (installed)( go to a daewoo dealler and ask for the ecu pinouts. if i can find my own, i'll load it up)
faze boost gauge
apc fuel ratio gauge
ebay remanufactured turbo xs rfl blow-off valve(cut spring)
2in intercooler pipe to intake
starion intercooler
8.5 mm spark plug wire
platnum 4 spark plugs (changing soon)
190lph walbro inline pump(not installed)

future plans:

upgrade injectors to 30-35 lb units
6:1 kit for vortech fmu
greedy type s blow-off valve
modify intercooler to side fitting pipes
install inline fuel pump
up boost to 7-8psi (stock goal: 200 hp) (modyfied goal: 300-400 hp)
street clutch or no springs racing clutch
forged pistons and rods(8.5:1 compression).
standalone ecu
boost controller
turbo timer
msd dis ignition box
custom stainless steel turbo manifold with a possible gt25 turbo upgrade
brake upgrade
custom bodykit

GsiTurbo · Post by **GsiTurbo** » Wed Sep 22, 2004 5:01 am

Very nice setup indeed!! Excellent info!

tango · Post by **tango** » Sun Oct 24, 2004 7:32 am

Erfinder wrote:I'm trying to remember which turbo was used on the 205hp C20LET ( 16V Turbo ) I don't know if it was a T25 or a T28.

It was neither. The C20LET used a KKK K-16 turbocharger.