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Old 10-18-2007, 05:42 PM   #21
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Originally Posted by TeeJayHoward View Post
Just finished reading the TurboByGarrett link. (thanks!)

I've got an '08 MX-5.

Assumptions:
Horsepower Target: 300BHP
Air/Fuel Ratio: 12
BSFC: 0.55
Wa: 33 lb/min
Intake Manifold Temp: 150F
Volumetric Efficiency: .95
RPM: 6000
Displacement: 2.0L
Atmospheric pressure: 12psi (Denver)

(33*639.6*(460+150))/(.95*(6000/2)*122) = 12875148/347700 = 37psia
37psia - 12psi = 25psig

So I'd need to hit 25psi of boost to achieve 300 flywheel horsepower, right?
you should be able to get that intake temp down more with a good intercooler. also, volumetric efficiency is supposed to be near 100% under boost, or so I'm told. does the duratec engine hit maximum HP at 6000RPM?

http://www.squirrelpf.com/turbocalc/index.php is a nifty calculator.
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Old 10-18-2007, 05:44 PM   #22
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150 intake temps is VERY hot. ping central.

i usually do 90-100 at the most for that calc.

which puts you to like 18psi.

Is the redline only 6K on those things? the higher the revs the less boost is needed really.

i also take VE out of the equation.
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Old 10-18-2007, 05:44 PM   #23
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Not yet anyway.

I got the book from Braineack's link, but it's a PITA to read anyway because it appears to the victim of a really bad OCR scan conversion. lol.

I just wanted to see what it looked like to know if it was going to be something I would want to add to my personal library.

The good news is the answer is YES. I'm off to Amazon right now to order it.

-Trent
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Old 10-18-2007, 05:52 PM   #24
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Originally Posted by Loki047 View Post
PS. Don't bother with a '08, sorry, as far as I know there is no solution for fuel/timing
Try not! Do, or do not. There is no try.

I'm betting it won't be too hard to get the EMU running on an '06+ MX5. Has anybody found a place to look at the NC wiring diagrams on line? Yeah, it's a scary new design, but hey, it's got fuel injectors and ignition coils. Nothin' new there.
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Old 10-18-2007, 05:54 PM   #25
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Originally Posted by Braineack View Post
150 intake temps is VERY hot. ping central.

i usually do 90-100 at the most for that calc.

which puts you to like 18psi.

Is the redline only 6K on those things? the higher the revs the less boost is needed really.

i also take VE out of the equation.
According to my tachometer, redline is 6650RPM.

Should I be using 14.7 for atmospheric pressure? Trying to find a turbo with a Pressure Ratio of 3.5 and an air flow of 33lb/minute is impossible!

Quote:
Originally Posted by Joe Perez View Post
I'm betting it won't be too hard to get the EMU running on an '06+ MX5. Has anybody found a place to look at the NC wiring diagrams on line? Yeah, it's a scary new design, but hey, it's got fuel injectors and ignition coils. Nothin' new there.
Corky's supposedly got the engine management already figured out.
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Old 10-18-2007, 06:07 PM   #26
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**** news to me. COol though
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Old 10-18-2007, 06:43 PM   #27
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Quote:
Originally Posted by TeeJayHoward View Post
Just finished reading the TurboByGarrett link. (thanks!)
(33*639.6*(460+150))/(.95*(6000/2)*122) = 12875148/347700 = 37psia
37psia - 12psi = 25psig

So I'd need to hit 25psi of boost to achieve 300 flywheel horsepower, right?
Only if your turbo is too small.

You should be looking for a turbo with a pressure ratio around 2 with about 35-40 lbs/min of compressor flow.

Mark

Last edited by Markp; 10-18-2007 at 07:44 PM.
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Old 10-18-2007, 06:48 PM   #28
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Originally Posted by Tesseracter View Post
I've spent over an hour playing on that site instead of working now. Are you trying to get me fired or something?
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Old 10-18-2007, 06:59 PM   #29
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Braineack, if you dont mind could I also get a copy of that book?

Thanx
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Old 10-18-2007, 07:15 PM   #30
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Originally Posted by TeeJayHoward View Post
I've spent over an hour playing on that site instead of working now. Are you trying to get me fired or something?
I was impressed with your math skills, so I figured if you were gunna do the calculations anyway, you should have an automated system to do it for you.

just think of all the time i SAVED you, by not needed to do all the calculations by hand! just explain that to your boss if they ask about your productivity :-P
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Old 10-18-2007, 08:11 PM   #31
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Quote:
Originally Posted by TeeJayHoward View Post
Just finished reading the TurboByGarrett link. (thanks!)

I've got an '08 MX-5.

Assumptions:
Horsepower Target: 300BHP
Air/Fuel Ratio: 12
BSFC: 0.55
Wa: 33 lb/min
Intake Manifold Temp: 150F
Volumetric Efficiency: .95
RPM: 6000
Displacement: 2.0L
Atmospheric pressure: 12psi (Denver)

(33*639.6*(460+150))/(.95*(6000/2)*122) = 12875148/347700 = 37psia
37psia - 12psi = 25psig

So I'd need to hit 25psi of boost to achieve 300 flywheel horsepower, right?
Tell you what if Andyfloyd's 2.0L BP can make 300 mustang whp at 17 psi with a 3271 i think a 3071 or similiar would be a pretty good match for you. Part of picking the right turbo is looking at what others have done with similiar products. Airbrush took a 01 with a 1.8 and made almost 300 whp at 14 psi, Y8's took a 2860 on his 99 1.8 and made 250 whp at 8psi. I dont know how if the NC motor has the effeciency in intake and head design but given that the base hp is about 40 more from the start i think with a turbo sized from 2860-3271 would be ideal for you. They should spool well and have the headway to hit 300 whp. The key here is maximing your BSFC with timming and cooling. The cooler the intake stream is the more power you can make with more timming, then the VE goes up and pretty soon you will be sitting at 110% + pretty easily.
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Old 10-19-2007, 10:00 AM   #32
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Quote:
Originally Posted by magnamx-5 View Post
Tell you what if Andyfloyd's 2.0L BP can make 300 mustang whp at 17 psi with a 3271 i think a 3071 or similiar would be a pretty good match for you. Part of picking the right turbo is looking at what others have done with similiar products. Airbrush took a 01 with a 1.8 and made almost 300 whp at 14 psi, Y8's took a 2860 on his 99 1.8 and made 250 whp at 8psi. I dont know how if the NC motor has the effeciency in intake and head design but given that the base hp is about 40 more from the start i think with a turbo sized from 2860-3271 would be ideal for you. They should spool well and have the headway to hit 300 whp. The key here is maximing your BSFC with timming and cooling. The cooler the intake stream is the more power you can make with more timming, then the VE goes up and pretty soon you will be sitting at 110% + pretty easily.
3271 (journal bearing) is smaller/flows/costs less than the 3071 (ball bearing). Quickly glancing at the compressor maps, the 3271 looks to match the 2860RS in terms of "size". Without really looking into it, I feel that the 3076 would be nice on the NC.

Y8S used the 2876 not the 2860. At least at the last dyno day... I had a tick more hp than him (~240rwhp) but he was around 8psi with his 2876, i was at 13 with my 1544's.
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Old 10-19-2007, 01:11 PM   #33
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How much boost is too much boost?

What's the limiting factor here? Obviously you can't take a 14:1 CR engine and push 100psi through it. Something will give. But what? The NC has a stock CR of 10.6:1 (10.8:1 depending on where you read). There's plenty of bottom end bits to soup it up, but what really is needed?

How does compression ratio fit into the whole turbo schema? It seems that 6-8psi is "safe" on my motor. More than that requires pistons/rods. Why?
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Old 10-19-2007, 01:49 PM   #34
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Cooling and maximum cylinder pressures will tell the tale. Along with octane rating hell alot of alchohol V8's run high comp ratios to make up off boost HP on there 900+ hp cars.
Tim IDK i was just shooting of the top of my head i never could get the squirle perfomancechart for the 3271 to work for me. But i take what you say as truth as I alot about garrets or turbos in general compared to you. I was just trying to give him a ballpark to play in.
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Old 10-19-2007, 02:09 PM   #35
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I hear ya I actually don't use any programs even though I should. I just look at garretts maps directly and imagine lines thru them. Then make sure there's headroom.
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Old 10-19-2007, 02:11 PM   #36
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here's how a 1.6L would look with a 2871 to make something around 300BHP @ 7K

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Old 10-22-2007, 02:30 PM   #37
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Originally Posted by Braineack View Post
here's how a 1.6L would look with a 2871 to make something around 300BHP @ 7K

https://www.miataturbo.net/~web1_bra...dom/gt2871.jpg
Would that really produce 300BHP? A "GT28R" (Which I'm assuming is any of Garret's GT28xxR line?) on a 2.0L non-VVT Duratec produced only [email protected] Granted, the engine doesn't have VVT, and has a 10:1 CR instead of a 10.8:1, but would those two things make up for the approximately 60WHP loss?

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Old 10-22-2007, 02:33 PM   #38
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Dude look at the chart he is tracking around 2.25 PR or 18.3 psi wich i think is abit high but within reason.
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Old 10-22-2007, 02:49 PM   #39
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the 28RS is a bit smaller than the 2871 too. but yes I'm displaying it at 18psi.


remember, you have to determine how much lb/min 300hp is.

I use HP x AFR x (BSFC/60)

or 300 x 12 x .00916 = 32 lb/min


so you know you at least need a turbo that makes 32 lb/min. Now look at the above map, at 32 lb/min & 7000RPM the thing is most efficient. Then you gotta figure you need X amount of PSI to make the goal. Which I determined on a 1.6L to be something close to 18psi. Then I can plot my map as I've done above.


this turbo could produce something like 350rwhp easy.



300BHP on teh GT28RS would look something like this.... about the most it can do:

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Old 10-22-2007, 03:45 PM   #40
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Quote:
Originally Posted by levnubhin View Post
Braineack, if you dont mind could I also get a copy of that book?

Thanx
Read the thread before you post, then go buy the book instead of stealing it from Corky.
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