What level of boost are you getting at a given rpm? How about downpipe diameter, i'm only asking this because if it is really such a slow spool, than i might return mine!

A 6258 spools as fast as a 2560...no problem. Will also pull till probably 350tq easy.Personal experience.

forged pistons give a good bit of insurance, while learning to tune. Assuming this is going to be tuned by yourself, a button clicking toonernoob, I would want that headroom. I sure used up my engines 9 lives...a few times and everything is aok.

I second that a 2860 sucks balls.

I had one, on a 2002 miata, with a begi cast manifold > 2.5" downpipe and exhaust. 10psi wastegate only boost control.
That turd hit the power at like 4500-4800rpm, where my 6258 takes off at 3200-3300rpm. same as my ex 2560r but makes 309hp instead of 265hp at same 17 psi.

ridetheclitche has a gt2871r setup, and he is spooling really well on a kraken T25 setup
https://cimg7.ibsrv.net/gimg/www.mia...8c558daf5b.jpg

Well, the opportunity just arose to pick up a cleaned up and rebuilt BP4W head with supertech double valvesprings, and supertech hi flow intake and exhaust valves, for $500... Will I see enough benefit out of these to warrant the investment with my goals?

That is 200tq at 3100rpm - pretty good and a big argument for going the "cheap" route

You'll make your goal on any BP head with the turbos mentioned. That head would just get you there at less boost with more area under the curve.


I'm definitely sounding like a broken record at this point but if it were me I'd probably take the forged piston money and trade it for that head.

Very cool, but that's not something the average person is going to find with a quick internet search.

the efr is not hard to find for a good price.

Plz halp meh t00n mah vvt.

Seriously... my setup isn't optimized at all. VVT is going nuts and oscillating like mad down low so there are likely some gains left down low. Those VD logs are with a Squaretop as well which didn't really act as expected. Maybe I have a boost leak from things. I'm honestly not really sure.

In any event... Is fast man. Point being, yeah... It does spool better than expected. I see 12-14 psi at 3200 like I did with my '2560' FM Ewg setup and it takes off from there. It's kind of a wonderfully weird feeling to realize that the turbo is just now starting to get into it where the old one was tapping out.

look at borka's EFR 6258 plot, same Kraken setup, BP6D, blah blah https://www.miataturbo.net/dynos-tim...9/#post1486956

He is hitting 200tq at ~3200-3300rpm. I didn't know that a 2871 can deliver as much torque down low as a 6258, but it does. Can't wait to get my GT2560 running on the Kraken stuff!

The Kraken stuff has some kind of voodoo magic built in. I am hitting 10psi and 175ftlbs at 3200-3300 rpm on a 1.6 with a 2" exhaust, a TD04 and a crappy street tune made by me (who has no idea what I am doing).

Borka and I have spoken quite a bit about our setups, so I've seen that a few times. You have to remember that I'm pushing more boost than he is and I believe my timing map is more aggressive so there are certainly differences in the setups, but yeah, lower down in the region you're describing that's not a factor.

If you look at the latest logs I've posted on my thread, the VVT angle, duty, and target are all going a bit haywire in the active zone, so I'm just saying that there's a chance that my spool could be slightly better if that was dialed in. I'm just really not sure how to do it, so I've been reading up on how to confirm angles and then just tuning it like I did EBC.

But yeah; TLDR; these outdated turbos still have a few things going for them with a good manifold and exhaust setup. I'm pretty pleased with the torque curve. EBC is fantastic.

300whp is dope. That was my favorite power level ever. 350whp just blows tires and transmissions and axles.

at 300 my 245s wouldn't hook in 3rd on the street, also would spin in 4th if it was cold.

EFR6758.

Do you have a dyno or log/virtual dyno of your setup as it was at that time (and/or later)? If so, please post it!

Dunno. Take my 380whp dyno and flatten the torque lower

Went and found Aidan's ish...

15 and 20 psi runs .
https://cimg8.ibsrv.net/gimg/www.mia...ed61f9d950.png

Allofit.
https://cimg9.ibsrv.net/gimg/www.mia...1a1ee64214.png

On my phone, so this is a pain in the ass, but it looks like he hits 200 rwtq and also full boost about 500revs after I do. More valid comparison will be after I get to the dyno. I think his timing map is much more conservative than mine as well and from his thread, it seems the he was still on setup mode for ebc so there's likely some ish there.

Why does Aidan's car make 7psi at 3000rpm and 14psi at 3600? Acamas made 10psi at 3000rpm and 18psi at 3400rpm. https://www.miataturbo.net/diy-turbo...6/#post1441885

Aidan does 150tq at 3300, 200tq at 3600. Acamas made 150tq at 2700rpm, 200tq at 3200rpm. https://www.miataturbo.net/dynos-tim...-scared-95108/

I am also incredulous of your VD plot. My old 2871R was about as bitchin as it gets, even compared to what you can build today. Real Garrett CHRA, Absurdflow manifold, E85, VVT head, open 3" exhaust. Didn't make 200tq until 3500rpm. Your VD plot soundly beats those numbers, which makes me doubt the validity of that plot. http://img.photobucket.com/albums/v3...E85-351whp.jpg

Look at my last dyno plot. Torque is on the right side.

150ft/lbs at 2700 rpm, 200ft/lbs at 3300ish?

https://cimg3.ibsrv.net/gimg/www.mia...8d832c5666.png


Not sure about boost levels. I had multiple issues with my dual port wastegate leaking, could have been the cause there

A couple of thoughts:

First, Virtual Dyno is tricky to get right. You have to be extremely careful to get the car data entered correctly, because it's very sensitive to weight, drag, and gearing info. You also need to make sure that the road you're running on is perfectly flat, and that the tires aren't spinning. It is possible to get a VD graph that matches (say) a dynojet one from the same car, but it's not easy. Your charts do not look like normal Miata dynojet charts -- the torque builds more quickly than anyone has seem from that kind of setup before and the torque curve from 3900 to 5500 is much too flat. Miatas with stock cams almost always have a noticable peak in torque around 4800 RPM, that's just what the cams are tuned for. (turbos with boost spikes or centrifugal blowers may differ due to boost levels).

Second, if you want to measure spool, the way to do that is with a regular datalog and to look at MAP vs RPM, not at wheel torque. This removes a lot of the variability in the virtual dyno approach, because spool is being directly *measured*, rather than inferred based on a calculated value with a lot of mystery coefficients in it. We actually have a whole thread for comparing spool numbers. :) Note that spool is heavily gear-dependent, because in lower gears the RPMs rise too quickly.

FWIW, my GTX2863R hits 150 rwtq at 2700 RPM, 200 rwtq at 3500 (on a dynojet in 5th gear), 7 psi at 3150, 10 psi at 3500, 14 psi at 3700, and 18 psi at 3900.

--Ian

...no? :)

Look closer at the chart. The lines you are referencing are demarcation lines for horsepower, not torque. There are no torque demarcation lines, so you have to extrapolate. I see 150tq at ~3000, 200tq at ~3500. I also won't fault you because the pull started at 2500, not 2000rpm as God intended. Also, your dyno operator deserves to be slapped for not scaling horsepower and torque the same.

Could be. You definitely have an issue somewhere. Next time you're on a dyno, set overboost to 220kpa, wire the wastegate shut, and let it rip. With a 4-port setup, you should be right on that line to within 200-300rpm of peak boost.

You definitely have boost control issues, IMO, based on those dyno plots and spool datum.