DOHCPanther

Duh typed in exactly what you gave me and an studing now.

DOHCPanther

Ok ,now I guess I am not as stupid as I though. I needed the nomenclature but the compressor maps mirror what I am used to seeing in turbine engines. Many of the options listed are mute as I am only buying what is offered form Bell or FM.

I went to the Garrett web site and there are some examples. I am lucky as they are using a 2.0 and 400 flywheel hp. I can use this for an idea about the stroker.... reading... reading.. Wow it ends up with a 3071r on the Garret site. Of course that is a 2.0 at 400 flywheel but man that is right in the area I am striving for. I do need a stroker for this though.. humm this is pricy.. I can hear you guys now chanting V8, V8, V8. I know, I know but I have my reasons. I am going to try to do thew math on a 1.8. Man I hate math. (I was a drop out in 9th, I was so smart back then)

hustler

iTrader: (6)

You're a sad person. There are a lot of people who run their mouths on the internet, but this is just unbelievable. I promise you that whatever you buy will incorporate something develop by the man you've deemed mentally unfit for your dollar.

The total lack of respect for people is astounding. I hope that whatever you do in your life, you learn to respect people of all ages and hold a realistic viewpoint. Right now you look like a bigot. I don't have much respect for you after this asinine bullshit, and I doubt I'm alone. Have fun posting here, you probably won't get any help again.

sixshooter

iTrader: (12)

The guy who originally engineered the small block chevy is dead.
I guess that means the lsx v8 swap is out of the question now.

I wonder if the guy who designed the Lexus v8 has retired yet? There might still be hope for you there...

1slowna

iTrader: (1)

hmm i think you are going to wrap your miata around a tree on 9lbs of boost.
i recently bought my 92 miata all i did was put on an rx7 maf threw it on the dyno and put down 107whp, then i bought a nitrous kit used for 200 bucks and put a 60 shot on it, it made 159whp. have you felt a 159 whp 165lb miata? i know its not as fast as it feels but its a hand full on 205 street tires. iv driven multiple 600+ whp mustangs and its nothing to keep them going strait. you get into this short wheelbase stuff and it can get ugly fast.
i plan on doing a bp swap by the end of febuary and building my own turbo kit soon after, i odnt have a goal number my goal is to have a fun to drive car, i will just push the stock bp to its limit and if it blows up il buy another one for 500 bucks.

sixshooter

iTrader: (12)

Learn some math. Engines are math in motion. I searched for you and found this info that contains the magic mystery math that makes the choice for you on what size you should use for a given engine size and rpms.
Posted elsewhere on the web (from a Mustang site):

Picking A/R comes down to spool time vs. top end power band.
You need to decide where you want your power band and plan accordingly from
the start.

Power band should not only decide A/R, but cam selection, heads, intake
compression ratio, rear gears ..... there's a lot to this and no magical
method or perfect right or wrong answer.


Using and reading Compressor Maps

First we need engine air requirements.

( cid X .5 X Ve X rpm ) / 1728 = cfm
( 14.7 + psi ) / 14.7 = P.R. (press. ratio)

P.R x CFM = boosted CFM

boosted CFM / 13 = lbs/min

So we have a 302 with Ve of 80% and 6,000rpm power band
wanting to run 15psi.

( 302 X .5 X .80 X 6,000 ) / 1728 = 420cfm
( 14.7 + 15 ) / 14.7 = 2.02 PR.

420 X 2.02 = 848 cfm boosted
848 / 13 = 65.2 lbs/min

65 lbs/min and 2.02 PR are the numbers needed to plot
out on your compressor map.

You also need to do the calculation at the rpm that full
boost will first be reached and make sure it does not cross the
surge limit line to the left at the map.

You want your plotted points to remain inside the map and as
close to the center as possible, while using smallest turbo that will
meet your goals. For twins just divide the turbo load in half.

Good link for turbo and s/c compressor maps.
Same calculations can be used on an s/c compressor map too.
Turbo and Supercharger Maps

And if you only want to buy a turbo once as you said, you damn well better learn to read a compressor map.
The numbers are what they are. No more, no less.

samnavy

iTrader: (7)

That is the dumbest first sentence for a NOOBs first post that I've ever read. Why don't you go over to the Meet&Greet section and make your second post there, since that's what that forum is for. Introduce yourself, fill in your profile info and your signature.

And for info, there are plenty of people on this forum with 15+psi 300whp daily driven Miatas that have no problems keeping them on the road.

spike

One of the dumbest most ignorant post I have ever read on this forum to date.

Obviously this place is not for you,you seem really thick headed & numb to the advice given to you by people with experience,I strongly suggest you leave this place and head on down to miata.net.

DOHCPanther

Cool, I remember having this excell spread sheet from way back. I didn't understand how it worked but I knew it was worth down loading. It is a work sheet based off the math from Garrett. I am only concerned with the top section about sizing right now so I didn't fill out the rest but take a look. I am at sea level so I used 29.92, I also have the compressor map for the 3071R from Garret that has their calculated points for the 2.0l. I marked my calculation for a 1.8 in the dark red. What I don't know is whick A/R FM and Bell are using because there are several 2860s,71s.

From reading the 2871 is right there for my needs. This would be a possible with or without the stroker. The 2860 looks a little low on the power potential. Hmmmmm

DOHCPanther

Ok, I never ment to disrespect the man at all. I know what he is about. I understand how his knowlage has impacted the development of the turbo systems. I know about his back ground I spoke to him several times in length. Edit: (I never said mentally) Several hours at his shop and then several hours on the phone. I think he knows it too otherwise he would still be out their cracking knuckles with the kid.

hustler

iTrader: (6)

I am trying to respect this supporting comment, where you stand behind your idiocy and believe that your elders (and intellectual superiors) are intellectually inferior and most likely senile, but for some reason I can't bring myself to respect an ******* like you. You are the herpe on America's psyche. This thread is full of unfounded opinions and generalities which you stand by, sustaining logic, and you've managed to top it off with bullshit disrespect.

I am not surprised that a guy who wants to do burnouts is a bigot, lol. You should reevaluate your thinking before your children join the klan. How old is your Gran Dragon or Imperial Wizard? Do you disrespect them too?

DOHCPanther

Wow, I didn't mean to **** on your god. He is just old. Not stupid, not senile, stop putting words in my mouth. Here is one for you maybe that is why FM split ways with him??? Fact is he did hand over the torch. He did state that it was time. (as in hes getting too old) Read for your self. Time for a new generation.

hustler

iTrader: (6)

lol, keep posting. You're digging out...and putting words in other people's mouths. I can't believe they give you a gun.

I genuinely wanted to help you make a better decision because I could see some of myself in your irrational statements from when I was younger. However at this point I can't really help you. You've pushed logic aside a few times, and now you're busting out with this stupidity. I don't think anyone here really cares where you put your money, we just don't want to be associated with you. I know I don't want to be the guy associated with age discrimination. I pride myself on progressive thinking, respect, and social productivity...hence my commitment to public service.

I don't want to get involved in some drama were people's lives and businesses are involved, but you're shitty comment disgusted me. Its now about discrimination and bigotry. I work with retired people everyday in my business and I'm apprenticing under a 71-year old man. I strive to be as well versed and educated as him. He's capable of anything and everything, irregardless of his age. So the next time you shrug someone off or disregard accommodation for someone based upon their age, hopefully you'll think of this syntax, and adjust your thinking because one day, you will be on the other side of this inequality.

sixshooter

iTrader: (12)

Please don't use the 7200 rpm number to pick a turbo, and also don't use 19+ psi as your pressure ratio (you might actually learn what the numbers mean if you do the calculations by hand).

First, pick an appropriate boost level, then calculate the operating range for the engine rpms where you would like to see boost. Example: 12psi at 3000 rpm, 4000 rpm, 5000 rpm, 6000 rpm, 7000 rpm. That will give you a line through the map.

If you touch the sides of the map or get closer to them, you aren't making power. You are off boost on the left (surge line) or choking and overheating on the right. The left side tells you at what engine rpms the magic turbo machine will come on boost. The sweet spot is the island in the middle. That is high efficiency land, good flow, lowest heat generation. You really should read a ******* book.

Then, try plotting the same rpm points with 10 psi, then 14psi. This will give you a nice idea of how that turbo might react in that operating range.

Oh, yeah, back to the book you didn't read. PSIHP. One turbo at 10PSI can make significantly more power than another at 12PSI. Flow is the key. Efficiency is the reason.

On second thought, because of the negative effects of the 11.0CR, scratch graphing 14PSI. See Savington's post above^.

And stay away from the top end of the map as well. The demon of overspeed lives there (cute little numbers to the right of your graph are rpms of turbo). Yes, Dorothy, that does say 140,000 rpms. How long do you want your $1,000 turbo to last?

P.S. Notice that the little purple dot hasn't even reached the center island in the 3071 map, and the engine is already out of RPMs. That is one of the reasons they said you were foolish to propose a 3071.

sixshooter

iTrader: (12)

Is there some reason that the 2.0l is at ~32PSI and the 5.0l is at ~10PSI on this graph?
Or did you just not know where the numbers came from because you were using an excell spreadsheet and not actually learning to adjust the numbers properly by hand?

I gave you the formulas and the explanations of each important number in the calculation. Plot it on the graph and post it here so we can see what you came up with.

sixshooter

iTrader: (12)

I got you confused with the 11.0CR guy on the other thread there for a minute. He doesn't have a clue what he's doing either.

DOHCPanther

Actually the other numbers came from here. Thanks for the insite about the lower RPM points. I will try that. As for 19PSI I thought I changed it to 15 and 18. I guess it didn't save. Also I appreciate the info on the problem areas of the map I will play with the numbers some more.

I have a clue about many things going on under the hood but turbo sizing isn't one of them.

Ok, Hustler I stuck my foot in my mouth. It would take a page to explain what I mean by that statement about his age. And in that explination I am sure you would point out that yet again I stuck my foot in my mouth. Apoligies to him and you. I do see that you are trying to help and you have. I have learned more from this thread than I have in a log time over at M-net.

9671111

iTrader: (10)

I totally agree. All old people tend to slow down and become lifeless husks. I wonder when they're going to just take him out back and shoot him.

DOHCPanther

Thanks but I am digging a big enough hole. LOL

sixshooter

iTrader: (12)

Did you plot anything yet? I seriously want to see what you found out. And ignore those bogus hp #'s that garrett was coming up with in the xls. Don't get distracted by that. It's not accurate.

That's one part of why I suggested that you use the formulas I took the time to look up for you. That and you will develop an appreciation for how each of the variables effects the result. If I was going to spend several grand, I'd want to know it inside and out.