Am I wrong thinking my 2860 should be able to push 20+psi? - Miata Turbo Forum - Boost cars, acquire cats.

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Old 08-22-2015, 08:23 PM   #1
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Default Am I wrong thinking my 2860 should be able to push 20+psi?

So after the car having an extended nap and getting most of it sorted I started trying top push the envelope a bit more. Plugged in 22psi as my boost target on the Hydra and I could get an initial hit of 24 but it would settle to 17. I readjusted my max duty cycle on the solenoid and didn't see a difference. The other day I was out with the car driving and flogging the hell out of it, got home and found the line to the wastegate had come off completely. Still settling to 18ish psi at 5800 revs with a spike closer to 24psi around 4000rpm.

.64 exhaust housing, 8psi internal gate. Ingersol Rand solenoid at 90% duty cycle

Time for a bigger snail?
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Old 08-22-2015, 08:37 PM   #2
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You can get a stronger actuator and probably hold a bit more, but overall it probably won't do too much more because it's likely choking up. A bigger hotside would also help, but again only so much.

Instead of the fascination with pressure (restriction of flow) you should be talking about hp output vs hp goals vs overall car goals.

what are they?
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Old 08-22-2015, 08:43 PM   #3
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HP goal is as much as i can get out of the 2860 before scrapping it for something new in the spring. The car has yet to hit 300hp on a dyno.

I'm not too keen on adding any more timing right now since the knock sensor just took a giant crap as well.
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Old 08-22-2015, 08:47 PM   #4
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What is your exhaust system like?
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Old 08-22-2015, 08:48 PM   #5
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Quote:
Originally Posted by Aricjm15 View Post
HP goal is as much as i can get out of the 2860 before scrapping it for something new in the spring. The car has yet to hit 300hp on a dyno.

I'm not too keen on adding any more timing right now since the knock sensor just took a giant crap as well.
If a disco potato can't hit 300hp on a dyno running full tilt with the wg line disconnected, there's a serious problem somewhere.
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Old 08-22-2015, 08:59 PM   #6
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Quote:
Originally Posted by 18psi View Post
If a disco potato can't hit 300hp on a dyno running full tilt with the wg line disconnected, there's a serious problem somewhere.
The last dino was on 15 pounds with cracks in the manifold. The car put down 275 horsepower and 250 foot pounds of torque. That was 3 years ago.

The exhaust is 3 inch from the turbo back with no cat
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Old 08-26-2015, 07:43 PM   #7
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Is the manifold replaced already? I pushed 17psi and came up JUST shy of 300 at 296hp/270tq. I would try the dyno again, make sure your AFRs sit between 12 and 11.5:1 and your in-boost timing is advanced enough to build power. I copied Paul's map for his 2560 setup to get to my power levels. I'd try a manual boost controller as well, maybe your WG is opening too soon?
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Old 08-26-2015, 10:22 PM   #8
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Quote:
Originally Posted by Aricjm15 View Post
So after the car having an extended nap and getting most of it sorted I started trying top push the envelope a bit more. Plugged in 22psi as my boost target on the Hydra and I could get an initial hit of 24 but it would settle to 17. I readjusted my max duty cycle on the solenoid and didn't see a difference. The other day I was out with the car driving and flogging the hell out of it, got home and found the line to the wastegate had come off completely. Still settling to 18ish psi at 5800 revs with a spike closer to 24psi around 4000rpm.

.64 exhaust housing, 8psi internal gate. Ingersol Rand solenoid at 90% duty cycle

Time for a bigger snail?
When I ran my GT3271 into the ground, it would do 28 in the midrange but drop off to 20 at 7,000 RPMs. But I was pushing it into choke flow, and it ended up killing the thrust bearing and the compressor wheel hit the housing. You might do some math and see where you're at on the compressor chart and make sure you're not a choke flow, cause I can confirm that turbos don't like to operate at that.
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Old 08-26-2015, 10:27 PM   #9
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he's close, but should be fine

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Am I wrong thinking my 2860 should be able to push 20+psi?-80-gt28rscompress_0ff693707a6528166d88e6aa5a2c74d55eba66f5.gif  
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Old 08-26-2015, 10:51 PM   #10
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Originally Posted by Der_Idiot View Post
Is the manifold replaced already? I pushed 17psi and came up JUST shy of 300 at 296hp/270tq. I would try the dyno again, make sure your AFRs sit between 12 and 11.5:1 and your in-boost timing is advanced enough to build power. I copied Paul's map for his 2560 setup to get to my power levels. I'd try a manual boost controller as well, maybe your WG is opening too soon?
The manifold was replaced after the dyno. The car is running in the area of 10:1 above 18psi, my fuel trims haven't had enough time to pull the fuel out of that area of the map.
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Old 08-27-2015, 01:42 AM   #11
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<p>You should be tuning fuel up there manually. That is really rich.</p>
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Old 08-27-2015, 10:00 AM   #12
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The rule of thumb I always heard was that an EBC was good for holding about twice the WG spring pressure reliably. Above that it would be more likely to crack open just a little and leak off pressure slightly. If you are interested in running around 20psi or more, try a 15lb WG and see if your results improve. Or wire the WG shut and see what KPA max really is.
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Old 08-27-2015, 01:28 PM   #13
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you musta missed the part where he said even with the line disconnected it still hit 20 then 17. I mean, even a 2560 can hit more boost than that with the line disconnected
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Old 08-27-2015, 01:30 PM   #14
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Sounds like the wastegate is getting blown open. Hence the wire shut suggestion.
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Old 08-27-2015, 01:33 PM   #15
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Maybe up top.
But a disconnected line should still make that thing spike WAY higher than 20 in the midrange.
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Old 08-27-2015, 01:37 PM   #16
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Default Am I wrong thinking my 2860 should be able to push 20+psi?

Line or no line, an 8lb spring will let it open eventually.
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Old 08-27-2015, 01:40 PM   #17
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Yeah true. I think a combination of weak wg can, small hotside, and perhaps other issues is contributing to this.
I just browsed a few dyno plots and looks like this is about the norm for this configuration. 350 is the absolute most I've seen it do, with most others in the 300 range.
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Old 08-27-2015, 02:04 PM   #18
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I had boost spike issues until I home-ported my turbine housing (channel/trench leading to WG flapper, see here). PITA but once done it's done.

Another thing folks haven't mentioned (maybe it was only me?) but if you're running say, 20 PSI and have an 8psi wastegate spring when the boost controller (either electronic or manual) opens the boost is going to overpower the spring and slam the WG door open/closed like a ragdoll. In my case on an 8psi spring with a manual controller adjusted to ~15psi I spiked to 17.9psi with fluctuations down to as low as 10psi, dropped to 14psi by redline. Putting in a 15psi spring (actually holds ~14psi at gauge/hydra) largely resolved this issue but I'm using a cheap MBC right now so it still fluctuates a bit. The best solution is a properly functioning electronic controller with a wastegate actuator no less than 1/2 of the boost level you intend to run though ideally.
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Old 08-27-2015, 11:40 PM   #19
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I know with the EFR if the boost line pops off with the 7psi spring and no preload I make 12 and it tapers, with 2 turns of preload it'll make 14 and hold it a bit then still taper. But thats the EFR with the mega massive wastegate flapper.
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Old 08-28-2015, 12:11 AM   #20
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I ran a datalog the other night. 24.9psi at 4900rpm. AFR is also rather rich at 9.1 since I haven't exactly tuned for that much boost yet.
It does look like as the Hydra leans itself out it is starting to hold boost better, keeping to 18psi by 6000rpm (11.0afr).
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