A proper setup for SCCA autocross
 

My perfectly good 1.6 is feeling too slow right now. :confused:Specially after driving my friend's STi.

I'd planned to keep my car NA but you guys are having too much of an influence over me. :bigtu:

If I were going turbo it'd have to be an excellent autocross car. My goals are:

175 whp
Full boost by 2000 rpm
Flat torque curve between 2500 and 5500 rpm

Budget is a constraint of course, but I'm the kind of guy who'd spend 1500 on a DIY job than buy an off-the-shelf BEGi S cause the latter doesn't fit my needs.

I did some initial research of what's available and made a shortlist of parts based on some compressor maps and reading corky's book. In your opinions, what would be the ultimate combo. Post up in following format:

Turbo - standard T25 sufficient? Alternative is a K03 180 hp model from Audi S4. Flows really well on comp side with a very small turbine for quick spool.

Manifold - cast log style (BEGi, JGS, ebay) or equal-length tubular (custom)? How important is the latter for quick spool?

Intercooler piping size - don't know if it matters, but generic ebay IC with 2.25" ok? anything better available?

Wastegate - Internal or External. K03 has a huge internal w/g BTW.

Fuel injectors (already have MS) - Stock 1.6 with higher fuel pressure, or is there a need for anything bigger?

Exhaust - Thinking of running a 3" with cherry bomb and side exit for quickest spool.

t20 :)

did someone say sr20 t25?

http://www.boostedmiata.com/dyno_day...am_samnavy.jpg

t20? where can i find one for T25-ish prices?

brain can you direct me to a compressor map for the sr20 turbo. How is it different from the regular T25 sold on ebay?

EDIT: is it this one: http://cgi.ebay.com/ebaymotors/Nissa...spagenameZWDVW

IC piping is really not a big issue, you will be ok at 2.25"
log style mani is good for quick response but can create problems with higher boost, again not an issue for you, if i was you id just build my own...
exhaust, 3" will help boost a lot
WG, either way really

what you do need is a stronger clutch and try to get a 1.8 diff in there

Turbo - t25... i'll sell you a rebuildable one for 50 shipped.

Manifold - whatever you feel like paying for.

Intercooler piping size 2.25 is fine

Wastegate - might as well stick w/ the already present internal

Fuel injectors (already have MS) - I'm not sure what your "MS" is. Be safe and get the 1.8's or bigger depending on if you like head room.

Exhaust - Enthuza exhaust is cheap.. having a shop make one from a cat and muffler can be even better. Side exit is not really an option on the miata.. search it out.. its been discussed.

It looks like you missed engine management unless the MS in your fuel injector section means MeqaSquirt. Obviously if you've been lurking this site most of us choose Megasquirt.

impretty sure he meant MS=megasquirt
as far as injectors go, he should at least use the supra ones, they are cheap and will do the job...

There is a discussion concerning the "perfect" NA/NB SM2 Miata build going on at Scca Forums Title:SM2 NA/NB Miata Build

They alluded to someone campaigning a turbo car in '05, and that it did well. Do you have any details on the car?

you cant expect your car to be fast without suspension work, good alignment and tires.
My Miata and my uncle's Miata and Geoffrey Chambers Miata are faster than any STIs on street tires on our region.

My Ex-sts2 setup

-Koni revalved
-Ground Controls
-800lbs front
-500lbs rear
-15/16 RB front hollow sway bar
-Bridgestones REo1r

Alignment
-2.7 in the front
-2.9 in the back
-3/8 toe out in front
- 1/32" toe in in the back

no, get the real deal:

http://cgi.ebay.com/ebaymotors/Garre...spagenameZWDVW

but i wouldn't pay more than $150 for a good one, $50 for a blown one.

For some reason I interpreted "SM2" as "SM". As in Spec Miata. Which made me wonder why the hell anybody would care... :nuts:

But insofar as the FI system is concerned, I have to agree that, even as a die-hard turbo guy, I'd probably choose a decently sized supercharger (like a MOAB) over a turbo for a car that was going to be a dedicated autocross-only weapon. Even with my little TD04H-15G and a very loose BOV, there is some lag. It's most noticeable on courses which have a long straight section either right after the start or after a very slow corner. What the S/C sacrifices in efficiency it would more than make up for with instant boost in those situations.


Since you already have MS, ditch the stock injectors and forget about AFPRs. Just pick up a set of 330 or 440cc injectors, depending on whether you're serious about only shooting for 175HP. 175 starts sounding like child's play right about the time that the two C6's park on either side of you.

Sorry, before my time.

I asked very similar questions about a year ago. I did extensive homework and went out of my way to drive as many FI'd Miatas as I could get my ass in.

After it was all said and done, I decided on a SC. I drove both a 1.6 and 1.8 with nicely tuned GT2554Rs. They were both 220+rwhp and both were in boost before 2000rpms which was a rush.

But...for an autocross application I felt that I would have to adapt to a different driving style in order to be fast. Not that it couldn't be done, it was just different and a much steeper learning curve. The instant boost of the turbo was nice, but also put the car at or beyond the limit of traction and control. Now going sideways is fun, but if you have autocrossed before, you know that's not the fast way around the course.

My recommendation is to find a few different FI'd Miatas and take them for a spin. Find somewhere to simulate autocross style elements and see how each car performs. Coming out of a slow tight sweeper was the main element that pushed me toward the SC. The SC'd cars would pull strong regardless of rpm and didn't require mashing the throttle to get going. I was able to take the sweeper smoothly. When driving the turbo cars, if I maintained enough speed to stay in boost, I was able to make a smooth transition and exit in control. If the corner was slow enough for me to fall out of boost, I would mash the throttle to get going and go from lagging to sideways.

Alright enough of a novel....

http://www.boostedmiata.com/technica...60trim_map.jpg

http://www.boostedmiata.com/technica...turbinemap.jpg

Only the S15 turbo is BB. And it's comp wheel has a 60mm exducer
http://en.wikipedia.org/wiki/Nissan_...mparison_table

http://www.turbobygarrett.com/turbob...R_466541_1.htm
"OEM turbocharger on Nissan SR20DET engine"

it's the same thing just not BB....60trim. 54mm, .80 a/r. coldside 53mm 72 trim .64 a/r turbine.


the S15 is a t28. 60mm = t28 54mm = t25.


if you look at today's graphs, then it's comparable to the

GT2554 54 as in 54mm. as long as the trim is the same, the map should be the exact same as well. the wheel design hasn't change, iirc.

GT2560 = 60mm exducer
GT2554 = 54.3mm exducer
http://www.turbobygarrett.com/turbob...R_471171_3.htm

Does these comp maps look the same?
http://www.turbobygarrett.com/turbob...1_3_comp_e.gif http://www.turbobygarrett.com/turbob...1_1_comp_e.gif

What's your major malfunction?
I even posted up both comp maps for you.
THE FUCKING MAPS ARE DIFFERENT YOU FUCKTARD.

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

Wow you are teh hax0r!

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.

pwnage

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.

:nono::confused: Is that what I have been doing wrong :eek:

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

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

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

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.

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

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:

http://img81.imageshack.us/img81/4817/airflowrpmrl3.jpg

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.

http://img206.imageshack.us/img206/7...airflowjq1.jpg

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

http://img235.imageshack.us/img235/322/compeffhr2.jpg

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.

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@ass ride :nono:, 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

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 :)

http://www.boostedmiata.com/dynos/dy...foreafter1.jpg

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.

http://www.boostedmiata.com/dynos/scott_vs_sam.jpg

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.

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...)

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.

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.

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.

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.

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

No, he had it right. I was pretty much saying that a Miata can't win SM2. Maybe someone will prove me wrong, but the Z06 and the high-strung RX7 are formidable competitors.

shawn, if anyone i think you have a pretty good shot with your set up
id really like to make it down to topeka one year but would not even consider it without a set of 275 A6's
as far as you making up the .66 sec i think you will have no troubles at all
from my experience, i know the most significant upgrades are your tires and suspension, you're already there, now just get used to the extra power and you will be very dangerous out there

ps-i envy your set up (sans FI)

also, when competeing in SM2 nationaly, you just pray that the ZO6's hit cones on each run, lol (inside joke that prolly only i get on this forum)

but regionaly, i compete on azenis and a decent suspension set up, still NA :(
but i do win frequently even when FI cars are present, but i have been killed by an LS1 RX7 and a ZO6 on hoosiers like damn, thats why i wont even think about going to topeka until i get 275's and boost

Thank you for the vote of confidence:)
There are three or four cars I know of around the country who are going to give it a pretty good shot.

How about you eat the BOV if one of us wins in San Diego? I will bring the good beer.

Well that's the last time I'll try and speak for you! :)

Mmmmm. Good beer.

Ok, maybe I'm being a bit harsh here to mask my own insecurity about sucking rather badly. :cool:

In all honestly, I'm really looking forward to seeing what happens this year, with your car and with the rest of the NAs on the new Hoosiers. With that new Uber, you're definitely on the right track, so to speak. :D

I'm not upset and it wasn't really harsh. And you certainly didn't underestimate the capabilities of those other car types. It should be an interesting year. I don't think I am quite there with the car yet, I need another winters worth of work to get it where I would like it to be. Then a few years of driver training.:skid:

I will bring the beer whether you have to eat the BOV or not.:friday:

Jay first off no one is perfect. I would not need christ if i were.

2- He was asking about a set up for autoX, turbo or not, best thing to know is how competitive he wants to be. If he wants to be really competetive then regardless of sm2 or not power is not the first thing he needs. How much expereince does he have. These all factor in. Like joe says its going to be hard to beat SM2 corvettes etc. The new hooiser might give us a chance but we have not seen yet. Also course differe depending on region. Some are small and tight, others more open. Having more than one turbo might be better, or an ecu that can store multiplemaps to spool differently. Setting up a turbo that is right for autoX is not as simple as i want to go fast and have X amount of power.

Dont listen to the nay sayers. No one thought a Miata could win in ES over the MR2s, but I guess I proved that wrong this year. I do think a SM2 Miata can win with the new tires available. My friend Jeremy Schuster was 4th I think in '05 running on skinny 225s and would have been a definate threat had the 275s come out sooner. It is too bad he gutted his car and turned it into a track only car. I may run some in SM2 this year, but in a '93 RX7 that I am helping my best friend build. We will be putting the motor together this weekend.

i have a 13g in my car, just the stock wastegate on it. i put a bigger fitting right into the compressor housing and i am seeing 7psi on my boost guage. for auto-x i think it would be perfect turbo. in first with my 205-50-15s, it wont spin unles you jab the gas and want it it spin. i would like to raise the boost to 15ish psi and see how it is. it feels a little slow in the higher gears, but then again the only other turbo car i have ever drove was an STI and my old v6 probe with a t3/t4.

thanks bryan for your input on the 13G.

Braineack I see what you're saying about the T25 and its definitely a good choice for someone wanting to upgrade to bigger hp numbers later on. In the dyno graphs you posted there still is no advantage over your T3 in the lower rpms right?

I did some research today and also came up with a third choice over the 15G and 13G: the TD04-13T found in the 02-06 WRX. This is a comparison of the three turbos:

http://img441.imageshack.us/img441/4...onchartqc3.jpg

I think the 13T is evenly matched in the mid-range, but its efficient even past 7000 rpm @ 12psi. Even on the turbine side it has to be flowing much better than the 13G and 15G cause it supports like 230 hp stock.

Some guys on this forum have also run this turbo with much success.

So with a little bit of hunting around I picked this up for $130 today:

http://img183.imageshack.us/img183/4...mals007fi3.jpg

http://img87.imageshack.us/img87/182...mals009jw4.jpg

http://img401.imageshack.us/img401/7...mals008zu4.jpg

Not bad huh...its from a 06 WRX!! Sure the flanges are a little mickey mouse and this means it wont be the cheapest option after all, but hey, its the perfect fit and what I've been looking for all along, atleast in theory.

What are the bottlenecks I can expect during the build?

I have scoped out a shopping list:

Turbo - TD04-13T

Manifold - JGS stage 2 kit with turbine inlet flange cut from a WRX up-pipe.

I/c tubing size - TBD

Wastegate - 13T stock

Fuel Injectors - Stock Supra

Downpipe - TBD. <--- This is going to be the tough part.

it's really only because i have a 3" exhaust now and headwork.

here's a better comparison. Same manifold/dp/exhaust, stock block. 12psi.

http://www.boostedmiata.com/dynos/scott_vs_sam1.jpg