Turbo choice - Forged 1.6... Please help
 

Hi guys

I have a fully forged 2004 1.6.
The turbo I was running before I forged was a Gt2560r.
It seems like a waste to forge and then run the little 2560 but on the other hand the responsiveness was nice.

I am now stuck :o(
What turbo am I best running for a good 280-300 hp?
I am not planning on running the car over 300hp but at the same time I don't want to be running the turbo at 100% all the time.

I have read so much conflicting information about the perfect turbo for a 1.6.
GT3071r, GT2871r, GTX2871r, GTX2863r have all been recommended but I just don't know what to go for.

I can give a full vehicle spec if that will help?

I really want to only have to do this once so it really needs to be right.

Thanks.

I had a close friend with a 300whp 1.6 93 miata with built motor and the disco potato gt28 ran great and still had good spool and power. His car was very fast and respresponsive. fun car.

The 2560 can be streched quite a bit, provided your IC is doing the job.

THe difference between 300 and 260/270 is about one or two seconds worth of boost. The response of a 2560 is there everytime you move your big toe. Response can also be assisted by the exhaust manifold.

Once pushed 360 out of a 2560. Slightly insane for the street.

Does one have the driver experience and skill to handle wheel spin at 90 mph? I thought I did when 25, still can't believe I crashed so many times.

corky

Thanks guys.

Been running 250hp for just over two years with a few spin up moments but nothing that's caught me out.

Well that's not true, I have been caught out but never ended up with me bending the car.

Tanks for the info.

Anyone with any experience with the GTX2860r and the GTX2863r?

Alex

Yes, considerable experience with the 2860. Sure, it works well, also, but just some lazier below 3k, or so. it makes 300 easier than the 2560, but what range of performance floats your boat?

corky

You keep discussing peak power without mentioning the actual use for the car.
if street car, use the 2560
if race car use something larger so keep it breathing easier and cooler

Thanks Corky

I like the speed the 2560 starts delivering boost but from what I can see from the gtx2860 it shouldn't be that much behind maybe 300rpm?

The car is predominantly for the road so I need drivability over masses of power.

Alex

18psi

She will be mostly for the road but I will be tracking her once a month at the most.
How come the 2560 will be better for the road?

Alex

18psi

She will be mostly for the road but I will be tracking her once a month at the most.
How come the 2560 will be better for the road?

Alex

Its not about when it produces 'some boost' its about the volumetric efficiency at the onset of boost.

The 2560 is a lot less lazy below peak torque than the 2860

Because on the street you want the smallest turbo that will do the job, it makes the car more fun and you're not stressing it enough to worry about living on the upper end of the compressor efficiency chart.

Once a month is relatively frequent. I'd probably opt for a slightly larger gtx flavored iteration such as the one you've already mentioned.

Nitrodann

I am trying to get my head round Volumetric efficiency.
It's proving to be a challenge.



18psi

Would you go for the gtx2860r or the gtx2863r?

Alex

either should hit your power goal, so the question is do you want a wee bit better transient response and "spool" or a wee bit more headroom

Response and spool all day.

looks like 325hp (300whp) is right in the thick of the compressor chart on the x60
you could even run it up to 350 if you wanted, it looks like

Volumetric Efficiency: Evol for short.

Imagine that one of the cylinders of your motor could hold 100 big molecules when it is sitting still with a valve open. That would be equivalent to atmospheric pressure filling up the cylinder while it just sits there and does nothing.

Now, crank it up and let the cylinder try to suck air in while the piston goes down and the intake valve is open. The air must get through the air filter, but some gets lost in the process. Then the air must go through some tubes, around corners and past the throttle hanging out in the middle of everything.

All those things impede the flow a little bit and some molecules get left behind. Then the air must get through the intake manifold and past an intake valve that's jumping up and down and acting like St Peter trying to decide how many and who gets past the gate. Sadly, too few make the grade.

So, when the intake valve crashes shut and this combustion cycle is cast in stone, St Pete looks around and counts only 85 molecules in the chamber. That is 85% Evol.

Evol looses significance with the turbo, as it can grab off gobs of molecules and slam them into the system. Virtually as many as you want. Sometimes, more than the motor can tolerate. The Evol fakery here is easily shown by comparing acceleration at full throttle normally aspirated ( zero on the Vac/Boost gage) with holding part throttle with turbo to hold zero on the same gage. In my example, the power would be 15% greater because the turbo completely trounced the Evol and relagated it to meaninglessness.

The turbo can then be called the great master that threw the evil Evol down the pit into never never land.

corky

Thanks Corky

That makes sense.

Alex

just run the turbo as is with more boost and enjoy slightly shitty low-end and good mid/top.

if you put anything large on that motor you'll have completely dog-shit low-end, sub-par midrange, and a peak hp point that only impresses on paper.

Braineack

Are you saying run the t2560r?

Alex

You should run whatever your end goal is.

Or check out & compare compressor plots between different sized turbos.

A gtx2860 seems perfect for your needs imo.