drewtam

To introduce myself to the forum.
I am Drew. I have '99, greenish blue. I live in Peoria, Il.
I have a disassembled TD04-13G, that I am considering rebuilding for the MX-5.
(Yes I know its a small turbo for the 1.8, I have the compressor maps and have done the extensive calcs).

I am trying to put together what I need to do this build. My goal is 220hp @ the crank. ~190whp.

What boost do I need to run to achieve my goal?
According to my calcs, 11psi would get me a density ratio of 1.61. That ought to translate to a power increase of 61% = 225hp @ crank. ~190whp.

BUT... FM website shows 8psi yields 190whp ~225crank hp.
BUT... the dyno results of some your cars show more similiar to my calcs.

So whats the story?
What pressures should I expect to need for my goal?
The FM website claims thier piggyback is all thats needed for fuel delivery, did I read that right, or will I need bigger injectors.

Thanks for your help,
Drew

Edit:
I am assuming 80% eff intercooling in all calcs, and I am assuming it is necessary for knock control and power goal.

Braineack

iTrader: (62)

my calcs say 7psi for 220BHP with a turbo the can support 24 lb/min

the 13g will fall a little short of that, only being able to deliver 20 lb/min efficiently at 1.5PR.

Their voodoo guy is only good for that amount of power, anythign more and it cant fiddle around enough to support the HP.



fwiw, 11psi is not the density ratio of 1.61, but the PRESSURE ratio of 1.748 ([11 + 14.7] / 14.7)


easier still,

assume you have 120rwhp and want 190rwhp

190/120 = 1.5833333PR

(1.583 x 14.7) -14.7 = 8.5psi

All this is saying is you know you can make 120rwph at 1PR since, the car is stock. 1PR is one atmosphere. So if you divide the power you want to make at the wheels, you can find the PR that it will require to make that amount, then you can convert that PR to the amount of boost it would require to acheive it.

In this case you still need to find a turbo that can support both 1.6PR and 24 lb/min, as it requires that much flow to achieve 190rwhp.

magnamx-5

iTrader: (7)

Drew you are confusing every one you want 200 whp assuming a 80% IC effecincy right well you will need some 300's minimum to make that gaol. Do not spend the $ on a FM vodoo system that is not a very good solution for hte money get an EMB/U, or a MS, or even a rrfpr very simple and effective. the 13g is going to heat the air quite abit i w9ould shoot for more like 13 psi on that for 200 whp. If you can i would et with Lazzer or loki to check out the local miata turbo scene and maybe show you a thing or two about how we do things. Also take abit more time posting next time you come across rather confusingly.

14b is a better option by far.

drewtam

Sorry, I thought my post was straight forward.

My goal is 220 flywheel horsepower.

The 13G was not a choice, it was free.
But, despite the efficiency drop, the map suggests it can pull the 8psi up to 7000rpm. If I went to 11psi, I would have to drop back the rev limit to 6500 to prevent killing the turbo.

Pressure ratio does not equal density ratio.
Density ratio = pressure ratio/temperature ratio (measured at the manifold, i.e. after the intercooler press loss and temp drop).

Isn't 120rwhp optimistic? Isn't it more like 110-115
At any rate, considering the difference between denisty ratio and pressure ratio. That is why I continue to calculate the need for like 11psi.

Drew

magnamx-5

iTrader: (7)

No you wouldn't but like i said 13 psi is what that turbo is gonna need to flow to make 225bhp. And if you outflow the turbo the boost just goes down. A used 14b is less than 100$ if you ever get tired of the 13g

Braineack

iTrader: (62)

Drew, dont bother with the density ratio in determining boost/HP, you're looking at the manifold pressures...

The Density Ratio is simply the actual air density divided by ISA standard Sea Level Air Density...how is that going to tell you how much air is required to achieve a certain HP

A density ratio of 1.61 means the air is 61% denser than sea level air density. How the how are you going to convert that to = % extra air required....it's not the correct formula.

1 Pressure Ratio = 0psi
2PR = 14.7psi
3PR = 29.4psi

Your engine makes 110 RWHP at 1PR, fine....what i gave was just an example....

look at my math:

Required Lb/min of flow = BHP x AFR x (BSFC/60)

220 x 12 x .00196 = 24.2 lb/min

required psi to achieve said BHP = lb/min x gas constant x (460 + Intake Manifold Temperature) / VE x (RPM / 2) x Cubic Inches

24.2 x 639.6 x 560 [460 + 100°F]
----------------
.95 x 3500 x 109.8

=

8667859.2 / 365218 = 23.7psig

23.7pisg - 14.7psia = 9psi (1.612PR)

I think i did my math wrong at first, but still, it's close. I mean it's just math, there are a lot of variables....now 9psi is what is going to be in the intake manifold, we dont care what the turbo is actually producing pre-intercooler, it doesnt have to factor in.

if you want factor in pressure loss, take:

23.7psig + 2, this assumes the intercooler drops you 2 psi.

then you need to factor in a loss at the intake or atmosphere:

14.7 - 1, this assumes your filter/maf/piping drop you 1psi

therefore: 25.7/13.7 = 1.87PR

so now look at your compressor map for 1.9PR and 24.2 lb/min (350CFM)

on paper, after all that, it looks like the turbo will work out just fine...but usualy I dont bother with the pressure drops and whatnot, cuase the first half gets you in the ballpark to what manifold pressure you need.

Braineack

iTrader: (62)

13psi on even 1.6L will make plently more than 225BHP!

10psi is 10psi is 10psi is 10psi is 10psi is 10psi is 10psi is 10psi regardless of turbo size.

If we assume the turbine can flow enough on both a large and small turbo and that both are within the compressor efficiency island then it's safe to say both will make the same power output at 7000RPM. But yes, if the turbo can't maintain the boost, or starts to just blow hot air, then it wont make equal outputs. The compressor map of the 13g will just be big enough, so now it' come down to the A/R of the turbine....

Drew, what's the A/R of that turbo?

y8s

iTrader: (8)

10psi is not 10psi.... that's why some 1.8s make 200 rwhp at 9 psi and some make 257 rwhp at 9 psi

I'll go back to my sewer pipe vs. straw analogy. if you put 10 psi through both, will they flow the same?

the real answer is either:

a) dont use that turbo because you'll spend more fitting it and be disappointed with the total outcome for the money

b) run it up to 9 psi and take what you get. more than that is hard on the 99 motors.

olderguy

iTrader: (19)

Could you explain this and quote some reading sources, please.

magnamx-5

iTrader: (7)

Exactly Scot listen to Y8's and Markp if this would hold true then there should be no difference in the power of a FM2 with a 2860 at 10psi vs a 2554 at 10psi, or a begi s3 with the same turbo's. Or a m45 and a mp62 both can flow at 10 psi but look at the power differences sean by those people. The losses due to heating the air are frigin rediculous, so it is just easier to start with a turbo that is more effeceint and heats the air less.

4sfed5

so to answer your question drew....use your turbo with some 330cc or 365cc injectors and an emanage blue unit to control fuel and timing, Get the thing to run as much boost as your fuel will allow or you get to your goal....Im running 190RWHP on a 1600 with 330's and no adjustable fuel pressure regulator, so getting 190WHp out of your system will be easy as long as you follow these rules.....

Fit a GOOD free flowing exhaust system of at least 2.5" diameter with mandrel bends.

Run your IC piping as cleanly as possible and use a quality I/C, not a puny SAAB or rx7 one.

get a base map installed then spend at least an hour on the dyno....tuning and dyno time are CHEAP horsepower.

drewtam

Thanks Braineack. But if you notice in your P=mRt/V formula you used, that the density ratio is built into equation. Its just a different formulation. If you think about it for a second, the density ratio is telling me how much air I can cram in. Therefore how much fuel. Its exactly the same calc you just demonstrated except in a different route.

But I think you helped me to find where I am messing up. It hit me when you said "we dont care what the turbo is actually producing pre-intercooler, it doesnt have to factor in"
I keep thinking in terms of compressor outlet, not manifold. So I keep thinking, 8psi on the outlet (especially in terms of engine survival limits of 10-12psi). Then I'm comparing to these other guys seeing 8psi claims of 190whp. But they are really got to be pushing 1.9Pr on the outlet just like you/we calculated. But altitude drops, intake, intercooler drops, all factor in for a manifold pressure ~8-10psig.

I agree 10psi is 10psi. With the big assumption all else is equal.

Usually all else isn't equal: the downpipe sizes, turbine outlet flange sizes, and the duct work from the comp. outlet to the chamber (pipes, IC, manifold, head etc), combine with compressor efficiency at various boost-flow rates; quickly explain why equal boost doesn't have equal hp.

TD04L-13G -6cm^2 => 6 cm2 = 0.41 A/R


DRew

magnamx-5

iTrader: (7)

Uh i dont run an IC and my totall intake tract is maybe 1.75 ft long i doubt i lose even 1 psi from the compressor outlet to the TB inlet.

drewtam

I appreciate your guy's help. I have got to save face at work.


Co-worker: Z28 LS1 with reflash
Boss #1: RX-8 Turbo
Boss #2: EVO-8 or 9? and SC'd Mustang GT
Boss #3: 351ci RX-7 (2nd gen?)
Boss #4: Firebird#1 (LS1) and Firebird #2 (LT)
Boss's Boss: 335i

Me: stock '99 Miata
they're like

Drew

magnamx-5

iTrader: (7)

Drew you willstill have trouble with those in the straights but when they need to turn it will get alot closer to beat them you need 270+whp

Braineack

iTrader: (62)

Betcha if you slap a 2560 on there with no other changes and keep the same exact boost level, your output with be very similar, with a little extra low-end to boot.

the same number of atmospheres is getting shoved into the combustion chamber with each turbo

the advantage with the larger one being less heat in the intake, and larger turbine for decreased backpressure, but since both compressors will support the same flow and PR, I dont see how one will make signifgantly more than the other, unless the 2560s turbine cant keep up.

one must first determine the amount of CFM require to acheive a desired HP, and then determine the amount of PR it will take to reach that CFM at a particular RPM....otherwise it would be nearly impossible to chose turbos per a particular application.

drewtam

Yeah, I know I'll always be the underdog. But if I can pull 220 flywheel hp this is the lb/hp comparison I come up with:
C5 9.7
flashed Z28 10.0
turbo miata 10.9
stock Evo 11.1
stock Z28 11.2
stock GT 11.5
(assuming 200lb driver)

With my .41 A/R, I am hoping for [advertising voice] "Insta-spool! When you need to spool fast." [/advertising voice]
This is my daily driver, so I think this aspect will work out well.

"the advantage with the larger one being less heat in the intake,"
That depends on compressor efficiency at the particular Pr and flow rate, not on the size.

"use your turbo with some 330cc or 365cc injectors and an emanage blue unit to control fuel and timing,"
I was afraid of that. So the stock injectors are not up to the task eh?
Can someone post a link to the "emanage blue unit"?

I've read I'll need a beefier clutch @ 200 lbf-ft, any recommendations on that end?

Drew

magnamx-5

iTrader: (7)

You wont reach 200 lbft with less than 230whp this isn't a SBC or KA24. But when it goes a ACT HD/XD is a good option for emanage info see the subforum on this site. Also 300's are controllable with stock ecu just fine, but you want the piggyback to be able to better fine tune it and do ignition timming cause you guys can't run a bipes, or a FPR :( Also i think your numbers are abit off
LS1 camaro with reflash 430bhp at 3600 8.3-1
Evo 8-9 330-340 bhp at 3500 lbs 10.6,10.29-1
Stock LS1 350 bhp and 3600 lbs 10.28-1
Stock GT 250 bhp and 3500lbs 14-1
SC GT 400 bhp and 3500 lbs 8.75-1
Miata at 230 bhp and 2450 lbs 15-1
I always use 2550 on mine to be pesimistic on what i can beat but you might not have AC/PS etc. Stock miata sans PS/AC wieghs a litle under 2200 lbs with a full tank of gas so the numbers work. I rather spend a little on a turbo that wont kill itself to make the hp then deal with your headache + spool is relative i think my 16g spools very nicely but others tell me the 14 b spools even better. 13g is just way to small for me to consider why run a turbo in the JRSC size range when you can run a turbo with the output ability of a mp62?

Braineack

iTrader: (62)

is that the turbine or compressor A/R? the compressor doesnt matter, it's the turbine's A/R that helps determine the speed of the turbo.

magnamx-5

iTrader: (7)

TD04-15G 15G 1.625 ind 2.187 exd 55 trim TD04-13G bored housing TD04L wheel 1.62 ind 1.86 exd TD04L-6cm2 6 cm2 is = to a 41 ar according to
http://www.stealth316.com/2-turboguide.htm