patsmx5

iTrader: (16)

This. I've already done the math, I can't crank the pressure much at all, as these pumps don't have much headroom at high pressure.

I'm going to either buy bigger injectors, or put some nozzles in the charge pipe to spray extra fuel into the motor. These pumps flow great at lower pressure, not at very high pressure.

deezums

iTrader: (3)

Besides the massive warb 450, which can do more than 300 whp on e85 at 90psi output.

From my figuring at 90 psi max, 5 bar base pressure, 20 pounds of boost, e85 .91 bsfc...

72+20= 92psi max pressure

500 hp x .91 = 455lb/hr

e85 is 6.59lbs/gallon, so 69 gallons/minute.



Yep, should be right on the button. Plenty for the majority of all miata out there, nearly enough for Pat's madness. Pat has extra 255, so it's fine for whatever. Quit being a puss and run allofit.

patsmx5

iTrader: (16)

This setup has been running for 24 hours and I'm at 22 PSI boost and have posted Virtual dyno AND a video already. Give me a break!

That said, don't use 20 PSI boost, use 30 and see what you get.

FWIW, I already did this on the SC, and at 100 % duty cycle my fuel pressure drops a bit up top. I'm running 65 PSI base right now, so 95 PSI total when running 30 PSI. I need to recalibrate the sensor, it reads the change in pressure right, but it reads low.

Like I said, gonna run bigger injectors or nozzles.

Sirnixalot

impressive results....looking forward to seeing what it does with more fuel

deezums

iTrader: (3)

Running 30 pounds pushes into the 100 psi/40-55gal/hr range.

That's atypical for most miata, but with two pumps it shouldn't be a problem. I wonder if it's just pressure losses from the plumbing or something.

patsmx5

iTrader: (16)

I didn't open my spreadsheet, but it's more like 70-80 GPM, not 40. That's with injectors at 65 PSI base, and 100% duty cycle.

patsmx5

iTrader: (16)

Thanks! Same here, should be awesome when I get it going. 22 pounds on this setup is nothing, big turbo is hardly doing anything yet.

deezums

iTrader: (3)

Well, working backwards...

72psi base pressure, plus 30 pounds of boost = 102psi

Chart says at 13.6 volts the walbro450 does 54.4gal/hr at 100psi

6.95lb*54.4gal/hr = 378lbs/hr

378lb/hr/.84~.91bsfc = 415-450 hp at the crank

So, with two pumps it should do fine.

patsmx5

iTrader: (16)

Small update, I do have one problem that I think I have figured out how to fix. The rear turbo is leaking oil in weird places. Like out the back of the turbine. But here's the best part, it doesn't do it when running or driving, only after shutting it down! Apparently I need a check valve on the oil feed and oil drain lines near the turbo.

I tested it and after shutdown, both oil lines dump oil into the turbo and flood it with oil. The return line is the worst, as it gravity drains a 3/8" line that's probably 8 or 10 long full of oil back into the CHRA. The feed line is not so bad but it still does it a bit.

So ordered some check valves, will install when they arrive. That should be an easy fix for that I hope!

I need to add up the cost, but I'm pretty sure I stayed under 2K for this build if you don't count the new welder I bought since my old one died on me mid flight... I still need a muffler and cat though, but still overall very cheap.

So far total problems are a leaking oil drain on front turbo (just tightened the loose clamp fixed that) and the rear turbo apparently needs a couple check valves. And a V-band I accidentally hit with the grinder is leaking, need to buy a 3" v-band gasket for that. Otherwise it's solid. Plan to up the boost to whatever my injectors will take for now and run it like that until I get more fuel for it.

Leafy

iTrader: (1)

If you put a check valve in the oil pressure line to prevent oil from flowing to the turbo when the car is off, you'll prevent it from flowing when the car is on too.

patsmx5

iTrader: (16)

As requested, boost from 5th gear starting at 2650. Not 2K but close enough.

3 PSI: 2780
6 PSI: 3034
9 PSI: 3330
12PSI: 3564
13PSI: 3633 (little turbo full boost of 13 PSI)
15PSI: 3956
18PSI: 4549
21PSI: 5001
24PSI: 5316

Wastegate boost control won't go any higher, Gotta fix this something is wrong. I turned the boost controller up 4 times now and it won't make any more boost. I think I need to run a separate line to the boost controller for the top port on the rear turbo.

MLV of this pull


VD of this pull


Question: Is this good or bad spool for a ebay GT28? 13 PSI by 3,600 RPMs? Seems ok to me, or at least acceptable.

Also 200 ft*lbs at 3,400, 300 ft*lbs at 4,800.

373whp at 7,864 RPMs on STOCK CAMS, Ebay cast manifold, and ebay turbos. Anyone wanna explain this? Still 332whp at 8,635 RPMs, which is 89% of peak power at 8,635 RPMs.

Very broad/flat powerband up top with some pretty cheap hardware.

More when I get boost controller working correct.

Also ordered the big magnaflow muffler, magnaflow cat. Thanks Lars for the heads up on where to buy the muffler!

Final VD for now, till I get boost controller working right. It's pretty consistent too, two pulls overlayed at the same boost level.

deezums

iTrader: (3)

Seems to be about equal with my t3, I get ~10 pounds at 3K, at least while it's still cold out.

Does this low end torque feel better to you than the supercharger?

Where'd that one sig quote go? Something about valves bigger than buttholes or turbos bigger than watermelons, pick one...

patsmx5

iTrader: (16)

No, the supercharger was way better from idle to probably 5,500-6,000 in real world driving. The turbo is way faster though, the powerband is broad and flat compared to SC. And stronger.

It was in the 70's when I did this testing.

Yeah I didn't think this ebay manifold/ebay turbos were going to be a problem at all as far as flow/power went. The fact that I'm making 90% of peak power at 8,700 RPMs kind of confirms that. Not many miata's doing that with any hardware.

patsmx5

iTrader: (16)

Also made a heat shield for the exhaust pipe today between the turbos. It's a shiny sheet metal shield with a .065" air gap. Works great, at idle the turbo wheel speed in the back is 4 or 5 times faster at idle, and you can feel the exhaust pulses where before, it was just a slow stream of air.

And it's simple/cheap.











Here you can see the ends are sealed to keep the air inside from moving, and to support the metal off the pipe.





only added .15" to the OD of the pipe!

patsmx5

iTrader: (16)

I'd install it so that it only allows oil to flow the correct way, but the check valves takes a certain amount of pressure to open. Hopefully the valve I bought takes say, 1 PSI to open so that when the engine shuts off, it will close and not gravity drain to the turbo.

nigelt

iTrader: (10)

So much amazing in this thread. propcats!

codrus

Now you just need to weld it gas-tight and pump the air out!

--Ian

hornetball

iTrader: (4)

I like that heat shield. Nice.

patsmx5

iTrader: (16)

Thanks!

haha, I think this is as good as it's going to get. Pretty sure I'm not welding anything gas tight with a flux core, and this shield would fail anyway with a vacuum. Interesting note though for those who are curious:

Thermal conductivity of steel: ~50, of hot air, ~0.05, so the air gap insulates 1000 times better than the steel, that's why it doesn't take much of an air gap to make a big difference.

Thanks! It works great. Better than the last design I made, this one is just as effective, but easier to make and easier to install, won't fatigue fail tabs like the old one did, and takes up less space, almost none! Making both shields took maybe 2 hours from start to finish, including removing the exhaust!

Joe Perez

iTrader: (8)

You did all this with a fluxcore welder?

Ok, I'm impressed. Compared to some of the TIGed stuff we see here, your welds look like ****, but compared to anything I was ever able to do with a cheap flux welder, they're actually pretty decent.