Braineack

iTrader: (62)

who's the fucktard now? oh wait you cant read this, nor could you read me previous post.

jayc72

iTrader: (14)

Wow you are teh hax0r!

Braineack

iTrader: (62)

gtx150 im so very glad you were smart enough to make another screen name. yes i did not do an ip ban, yet.

you were not smart enough too distinguish the fact that the t25 we keep referring to is not the GT2560R you keep linking.

if i was going to tell him to use a gt2560R i would have said use a GT2560R.

if i were going to tell him to use a S15 T28, i would have linked the GT2560R map, as that is the same. Or I might tell him to find an OEM GT28R, which is the same thing a the now GT2560R. Gee-Willicers how does that work?!

like i said before t25 = 54mm, t28 = 60mm

its great you are able to search and link and post and pretend you know something, but you saw "OEM sr20det turbo" on garrett's website and assumed a heck of a lot.

Zabac

iTrader: (39)

pwnage

ajtopal

iTrader: (1)

If you are going to go to SM you are going to need big tires be prepared to be looking into cutting fenders and getting 275 tires. A company called 949racing makes the wheels you need to make this happen.

IcantDo55

iTrader: (11)

Is that what I have been doing wrong

ajtopal

iTrader: (1)

of course not you've been going to straight you need to do the whole thing completely sides ways.

fourwhls

iTrader: (2)

Only if going sideways was the main issue. We don't call you 360 Mike for nothing.

Jefe

iTrader: (7)

FM 2 should suit your needs, the price is cheap and add a "Happy meal" for the tranny, can't go wrong

Pitlab77

iTrader: (3)

I am going to go against the grain here.

DO NOT FI if you want to autoX. You'd be best served getting a lot of seat time, a decent suspension, and a good aggressive alignment.


Your money would be best spent on V710's after getting really good on say Azenis. Try that first.

jayc72

iTrader: (14)

puh-leeez

I'll take FI please. Racing in stock class is teh suck. You might happen to have THE car for a while until something else comes out and you are fucked. At least if you are running SM2 there is a lot, providing you have the funds, you can do to make you car more competitive. In stock, buy a new car or bitch about getting fucked by the new classing. Stock class is where 99% of the bullshit politics occur and in MY opinion is what can turn a lot of people off. I ran ES on Azenis for my first year, I enjoyed the sport so much more when I did the suspension and ran RA-1. Now with an FI car on 710's I nearly blow my load every run I take.

You can learn to autocross on R's. You can even do it in a non-stock car. Besides, I don't think I want 10 minutes of seat time every couple of weeks to completely dictate what I do with the car. While you bask in the glory of a regional win in CS, I'll take my mid pack finish and bad assed ride on the street.

/rant

The_Pipefather

iTrader: (5)

Wow you guys are really fast. Thank you for all the inputs.

Just to clarify, I don't want the "perfect" SM2 car. My main aim is to learn how to put together a proper turbo setup from scratch to fit my needs that's all. I know tires and suspension make the difference in auto-x, but that's not why this topic exists.


To sum up, so far the consensus is:

Turbo - T25

Manifold - Log style

I/c tubing size - Doesnt matter

Wastegate - Internal

Fuel Injectors - Bigger than 330 cc on stock FPR with Megasquirt

Exhaust - Anything but side exit. Will worry about this later.


About turbo sizing. I'll tell you guys why I considered something other than the T25. I had always suspected that the T25 is oversized for my needs, but to prove my point I did some analysis this evening and I want to share the results.

First, I plotted this airflow vs. RPM curve for the Miata 1.6 engine at a pressure ratio of 1.8 (desired hp/original hp or 175 whp/95 whp). I had to make many assumptions to get this curve, but I think its fairly accurate for an autocross/street situation:



So in the 2500 to 5800 rpm range, the compressor needs to flow between 5 and 20 lbs/min of air. The compressor is assumed to spool up to 12 psi (i.e. 1.8 pressure ratio) by 3100 rpm at which point its flowing 8 lbs/min.

Then I made this chart and overlaid it on a few compressor maps.



That yields a compressor efficiency vs. RPM chart as below:



An efficiency of 0% means that surge or choke limits have been reached for that combo of airflow and pressure ratio.

K03-2072 (black line) is the turbo commonly referred to as K03-Sport in the VW/Audi community. You guys know all the others.

From this analysis, it looks like the 13G (red line) is the best, but the K03 and 15G (green line) come close. You can see why Greddy chose the 15G for their kit. The GT2554R (blue line) seems to be the poorest choice of all.

So what do you guys think about the validity of this analysis? Does it reflect real-world results? People with 15G and 13G turbos please post your experience.

I understand compressor maps dont tell the whole story but turbine maps except for Garrett arent that common, and I have to go by anecdotal evidence for the final selection.

Pitlab77

iTrader: (3)

and what makes your car badass on the street? and RA1's are POS for autoX they dont warm up at all. I have run a car in SM2 and a car in CS and honestly i'm having a lot more fun in CS. If your region is full of little crybabies, and it sounds like the crybabies might include you, that whine over everything to bad for you, thats not how it is in Houston. Hell SM2 has ever more politics actually because most of the people there are the ones dumping a ton of money into their cars to race. Like you SAID everything you said, including that you have a bad@*** ride , is your own opinion.

The original thread title asked for proper scca set up. The proper setup always should start with the Driver=>suspension/alignment=>power. A faster car can help a slow driver, but a fast driver can make a fast car even faster.

if this this was a thread about how to get a quick responding turbo that should have been the question, or maybe even in the DIY section.

so shut up and sit down.

thank you come again

Braineack

iTrader: (62)

I have a larger T3 -S60trim but I've experience the same result. a good 12psi and a turbo that can maintain the airflow and exhaust flow will net you a good flat torque curve.

here's a before an after of my system throughout a year span, the 200rwhp number is a stock 1.6L with a 2.25" exhaust. Then the same setup with minor headwork and a 3" exhaust



when you start getting into small turbos, you have to be careful that not only the compressor can flow enough that you need, but the exhaust side can move enough lb/min that it doesn't choke up, up top and you're torque drops off the map.



too bad we both lifted, but you can see both at 12psi, this being the previous T25 I spoke of, the smaller turbo needed no headwork or bigger exhaust to result in the same exact power below 6k. This setup also had the same exhaust DP and exhaust so the comparison is pretty good. But you see where his torque is about to start to drop and mine keeps going up

With that said, for a sub $200 price tag, this is why I think it's a good turbo for you.

Joe Perez

iTrader: (8)

I struggle with this. I went FI before I started autocrossing, so I didn't have much of a choice. It's straight to SM2 with the big guns.

Personally, I look at it this way- if I was serious about autoX, then I wouldn't drive a FI Miata. It's just never going to win. In fact, the day that an NA takes the top spot at Topeka in SM2, I will eat my turbocharger. However I'm not "serious" about autoX, it's just something fun to do. I won't let the fact that I'm FI stop me from autocrossing, just like I wouldn't let the fact that I occasionally autoX stop me from going FI.

So like I said earlier- if you are "serious" about this, and you're building a dedicated autoX car, then either skip FI, or install a big supercharger. You'd also best budget for some 15x10 wheels and several sets of Hoosier 275-35-15 A6s.

If however you're building a street car, and you want to play with the big boys when you autoX for fun, then by all means, turbo FTW.

That's unfortunate. Here in San Diego, SM is probably one of the most laid-back classes. Yeah, we've all got some money in the cars, but there are no professionals driving SM around here- just guys with HP addictions. Street Prepared is probably the biggest political scene, and even there you don't hear about too much fighting. It's just that in SM I wouldn't expect to get protested for anything short of a nuclear reactor sticking out from under the hood. (well, ok. If I were to show up in a Fiat Panda and start trophying every week, then someone might ask questions...)

fourwhls

iTrader: (2)

I really hope to see you chewing on some turbine blades in the next few years Joe.

I think the new Hoosier 275s have given the Miata a chance in SM2. There are a few of us prepping our cars to take a run at it. My car sits in the top overall spot or very close to it pretty much every month on a local level. Yes local, but we have some heavy hitters and net close to 150 cars an event.

Now that was in CSP trim and only 125 to the wheels. I only need to pick up 0.66s on a 60s course to maintain that position. I don't think I am going to have trouble doing that with the modifications allowed in SM2 and an additional 100HP.

jayc72

iTrader: (14)

He is asking about building up a turbo, and if you read the original post you'd see that he asked specifically about options on going FI: Turbo, manifold, piping, wastegate, fueling and exhaust. Not if he SHOULD go turbo. But of course you regirgitate the same tired old mantra with out looking at your target audience.

Enjoy running in CS.

Now that isn't very Christian of you, maybe it's time for another pilgrimage or something.

jayc72

iTrader: (14)

Joe isn't saying a Miata can't win, just that an normally aspirated one won't. It's going to take either a supercharger or a turbo to get it done. Since I assume the car you are going to campaign is your FFS car.

Joe Perez

iTrader: (8)

Woot! My terb0 1s 3ff1shunt! </leet>

But seriously. The TD04H-15G is a small turbo. It spools quickly, yet it's still reasonably efficient when making 12PSI at 7,000RPM.

On the other hand, it's a journal-bearing, non water-cooled unit. For some reason, that combination scares me. No problems yet, but all else being equal I'd choose a Garrett for the water-cooling alone.

Marty

Are you wanting to compete nationally in SCCA AutoX, or just your region? If you're competing regionally, go NA and run SM2. Save your money for beer for everyone. I won SM2 in my '94 twice in my region with just suspension and Victoracer's