T3 vs GT2560R performance on a 94 Miata

So I've gotten to installing the new intercooler setup on the Turbo Miata. Got into it and started looking and I'm going to have to reclock the turbo for the new intercooler setup. Little background, It's a Link FM II Kit that been installed for a long time. I've been slowly setting the car up for my tastes. 

So my thought process is this, I've got to remove the turbo anyways to reclock the turbo and I'm going to update the studs on the manifold as well since I've got to remove it. Is it a good time to update the turbo as well? 

Overall, I think the car is a little laggy. I've gotten use to modern turbos. The car will be a fun car that does get out to the track. 

Is there any good sources for turbos if I do decide to go that way? 

When I got my turbo NB I had to do some serious rework of the turbo kit.  I went from an unidentifiable (larger) Garret turbo to a T25 (Nissan Hot side and Mitsu cold side).  It transformed the car in a good way.  The larger turbo was always pretty lazy.  The T25 was a mid range rocket and had torque all the way thru the spectrum.  The only complaint I would have is tapered off after 5500 rpm.  I think the GT2560r would have all the great attributes of my older T25 with little to none of the drawbacks.     

A 2560 on a 1.8L should spool roughly the way a new turbo car does. The compressor is enough for a little over 300hp. In other words, an 11 second 1/4 mile pass in a Miata. So, basically it's all the turbo you'd need unless you're trying to do something pretty ambitious. 

Yeah, I was thinking that too Vigo. Not looking for anything ambitious. It's just a fun street/track car that I'm looking as much for reliability as I am all out HP. I figure if I need to do the BMW transmission swap then I've probably gone too far. It's currently running 12 PSI off a stock 63K long block. 

Being at 7K Ft. up, It's more like a 13 second car today. 

Vigo said:

A 2560 on a 1.8L should spool roughly the way a new turbo car does. The compressor is enough for a little over 300hp. In other words, an 11 second 1/4 mile pass in a Miata. So, basically it's all the turbo you'd need unless you're trying to do something pretty ambitious. 

I agree that a GT2560 is a great turbo for a Miata, but it's not going to spool anything like a new, modern turbo car does.  Expect it to spool up around 3500-4000 RPM, rather than the 1500 RPM you'll see in modern cars.  OTOH, it also won't be running out of breath at 4500 RPM, but should be good to redline.

The 2560 is basically what used to be called a T28. Neither are cutting edge, but the smaller guy definitely has the edge on response. A 3” exhaust helps with spool, as does compression.  But the 2560 is our default turbo for good reason. It will provide all the power a stock block can handle.

If you’re coming to Summer Camp next week, you can check them out in person!

Thanks Keith. The 2554 is basically a t25 right? I've been out of the turbo world since my turbo colt.

I may not be or may come miataless. Betty's new owner picks her up in 2 weeks and the NA is without turbo. I'm signed up and may just come to hang out. 

Hmmm, more compression. That is another Idea. Didn't think about that but I do have a very nice SM head with 49.4 CC chamber sitting on the shelf with little interest from buyers. Maybe she needs to be put on the engine.

Yup, 2554 was T25. 

I have a 2554 1.8 myself, I can try to get you a chance to check it out when you come. Very quick to respond but it has to be dialed back a fair bit at the top end to avoid knock. 

Compression and turbos are fun. Not for peak power, but for response. The ND setup we sell is all wrong when it comes to “what people know” about turbos but it responds really well due to that high CR. Besides, raising the compression at altitude is just compensating for the low ambient pressure!

Expect it to spool up around 3500-4000 RPM,

I've driven two t3/t4  (t3 turbine, t4 compressor)  1.8l miatas that  were fully spooled around that.  It depends on a few things, but i think one thing that characterizes the turbo miata community in general is thinking 'big' turbos spool slower than they actually do/will.  The one turbo 1.8l car i tuned with 3.63 gears would still make 5-6psi below 3000 rpm, and even with the 'tall' gearing it still felt great just riding part throttle boost down there. 

If you overlay the charts, you’ll often find that the big turbos are still making more power than the smaller ones throughout the rev range. But the big ones hit their maximum boost later and they hit it harder, so the difference between the top and bottom end feels exaggerated. 

That’s on the dyno, though. Lots of load and a steady state condition. On the street, the smaller ones definitely feel perkier with less lag. Dynos don’t show transients, and that’s where you feel it. I prefer driving my 2554 to the 3071 car we have. Actually, since we don’t sell the 2554 anymore I don’t usually let customers experience it because it makes the 2560 feel a little doggy. Definitely power limited, though, and it runs hotter because of the higher back pressure. 

So I get special treatment from Keith again.  No wonder I'm a loyal customer. Kidding.

So got home late from Dallas and didn't make it to summer camp......Boooo. So instead, I tore down the turbo off the car with the intent of reclocking it and just putting it back on for now. 

Found 3 interesting things. 

1. The shaft play was beyond tolerance for a T3 by a couple thousands.

2. The downpipe leaked. 

3. The plug on the exhaust manifold was loose and leaking too. 

So 2 and 3 are solved with the parts that were waiting for me from FM when I got home. 

I think the turbo is going to get swapped with a GT2554 once I have some spare budget for it. With the T3 needing rebuilt anyways, It made my decision easy. 

For whatever it’s worth, my 1.6L can spool a chinese T3 knockoff to 10psi by 3500 rpm.  The turbo never runs out of steam on the top end, but the poor head flow starts to strangle the power around 6800rpm. 

Also FWIW, you can get an S15 (Nissan) turbo, which is basically at GT2560R, for pretty reasonable prices.  I don't recall the nissan part# off the top of my head, but there's a few threads on this over on  MT.net.  It's old news, since everyone is after EFRs these days, and a few mods are necessary to use the Nissan turbo, but its a good way to get a BNIB Garret at a cheaper price point.

Actually I got a NIB Garrett GT2554R For under $700 which wasn't bad. So I'll basically have a new turbo system outside the exhaust manifold and the blow-off valve. 

I took the opportunity to see why they had a new head as part of the car sales package. Honestly, I see no reason why but It's a beautifully done head so I'm throwing it on with the coolant reroute as soon as it comes back in stock. 

Should be interesting. I cut out about 70 LB out of the car with removing the dead AC system and the malfunctioning airbags. I'll have a little bump in compression. If I measured right it should be about 9.6 to 1. 

I'm almost out of things to do other than sort it and enjoy. 

bmw88rider said:

I'm almost out of things to do other than sort it and enjoy. 

Bwahahahhaah :)

I know...I know...wishful thinking :)