$2008 GRM turbo Miata noob
 

Good evening. My name is Tucker and I just bought this car (http://www.tampabaymiatas.net/forum/...st=0&sk=t&sd=a) to compete in the upcoming $2008 Grassroots Motorsports Challenge. For those not familiar with the event, see here:

http://grassrootsmotorsports.com/events/2008-challenge/

We competed last year in an FC T-II and finished 18th overall. Hopefully this year will be an improvement. There are 3 guys on the team, with the addition this year of one guy's wife.

Given the fast approaching event date, I've focused my energy so far on gutting the interior and removing any uncessesary engine bay components. The only surprise so far were the completely rusted out floorboards that the previous owner failed to disclose. I hope to get the car down as close to 2,000 lbs as possible. Post-Challenge, I plan to use the car for auto-x, HPDE, etc, so creature comforts are of little importance.

Overall the car runs well, other than a rough idle and incredibly bad lag. I've done quite a bit of seraching here and understand that the Greddy kits respond quite well to upgraded DP's. However, given the budget constraints of the competition, I can't afford a Turbo Tony or BEGI version. So my first question is what are the DIY options? Should I just weld up a wide mouth version? And given the track only future of the car, would a one-piece version be feasible all the way back past where the cat would normally be located? The car has a ghetto 2.5" catback exhaust already.

In addition to this car, we are building a second turbo Miata to compete with as well. That project started with a $400 dollar POS and a stock Greddy kit that we found used, but never installed, for $400. So the DP quandry exists here too. There is a build thread here if you're interested: http://grassrootsmotorsports.com/for...ld/2097/page1/

There are two other Miata builds going on (yep...we're trying to get 4 cars done) but those two cars will have engine swaps. Chances are we'll only get the two turbo cars to the starting line.

As for me, I'm 39 with a wife and two kids and am a sales executive for a software company here in town. In general, I won't be chiming in with answers to much of anything, as I have much to learn versus much to teach.

If anyone is in or near Gainesville, we would welcome you to stop by, take a look, and turn a wrench if you must!

Thanks for your time and sorry for a long first post.

Is there a question in there? All I see are words.

Good luck at the event, it is one of the things I'd love to do at some point, along with the 24hrs of Lemons.

Werent we just recently laughing at the color combination of that car?

My main question at this point is what options exist to wring the most power out of the existing turbo set up while on a super tight budget.

Yes, the color combo was ridiculed here previously and is duly noted in my signature.:)

I say megasquirt with wideband, but just tune the car with the wideband and take it out of the car so it doesn't add to the cost. Install the MS directly to the stock wiring so you don't have to mess with fudging install costs. Sell the stock AFM and ECU to regain some value. Then proceed to enjoy the amazing drivability.

There are a bunch of ways to skimp on cost if aesthetics and the like are of no importance. Used truck intercoolers, DIY EMS (like the MS), etc.

For the downpipe, I'm no expert, but if you really wanted to do it on the cheap and had the materials, you could try re-using the greddy flange and enlarging the hole, then create your own bell-mouthed 2.5" DP. ...or just keep your eyes peeled for a used Tony/Begi.

Thanks for the suggestions so far.

cjernigan, MS is the goal. I bought the unassembled kit from DIYautotune.com and am trying to get it put together. And tuning it with a wideband, but then taking that back off the car, is a brilliant idea.

I put up several ebay auctions last night to begin selling off items I don't need. My budget is already at the limit, so to add things like MS, I've got to sell things off to free up budget money.

kotomile, unfortunately, asethetics are somewhat important, as concours judging is part of the scoring. Last year, we could only afford a rattle can job and it turned out okay. This year, I would like to go with the Rustoleum technique, either applied with foam rollers or a rented spray gun. And luckily the car came with an FMIC, so that's covered.

A homemade DP might have to be the answer. If that is the trick to more HP from the Greddy kit, we will begin fabbing up our own version. A local muffler shop lets us dumpster dive out back of their shop and there is plenty of 2.5" tubing to be had.

Here is a current picture of the progress...

http://i170.photobucket.com/albums/u.../P81701661.jpg

yep, gut it, MS it and sell EVERYTHING!

Define laggy. The greddy DP is a horrible piece of crap. Anything you do will be a massive improvement. In your MS budget did you remember to include injectors?

The turbo on the Greddy in my experience is all about midrange. Kind of flat down low but comes on like a freight train in the mid range. Mine always seemed to run out of steam up top, but I think that had a lot to do with the 2.25" exhaust.

How much boost are you planing to run?

Said to someone who just bought his first soldering gun. :) Long before I purchased the MS set up, I read through your DIY on MS several times. I am no less intimidated as a result. If I FedEx'd it to you, would you be willing to assmeble it?? I'd happily provide drinks of your choice!

Laggy on this car is nothing below ~4k RPM. Then everything hits at once. That's okay for the drag portion but will be tough to manage on the auto-x course.

I forgot to mention that the car is already running a Walbro 190 and 1.8 injectors. As for the question on how much boost I plan to run, I'll answer with a question. How much is deemed safe? I've seen 15 as an answer and I've seen 20 as an answer. Is there a consensus?

Even running the stock downpipe, the greddy kit should be hitting earlier than 4K..might want to look into why the power's coming on so late.

no that's pretty much true to a greddy and stock ecu.

Bipes must have really made a big difference then. When I had my '90 greddy (with bipes) I was seeing power aaround 2800-3000RPMs.

this shit is baller.

15psi Safe? Not with thoes injectors, you're stuck around 8ish.

20psi is probably asking too much from that turbo.

You also need to clearly define "safe". ie. daily driver safe? Track only with 110 safe?

I have a DP that I'll sell cheep:

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

Its going to need to have the greddy flange welded on to it but that easier than building a new DP. I know "china" crap but it needs to last a weekend!

I also have a Greddy on my car and 14psi makes 200whp and runs like a stocker with MS.

Safe is running on 93 pump gas, as nothing higher is readily available around Gainesville unfortunately. And it will mostly be a track-based car, not a DD.

So 15psi is out of the question with the current set up. Thanks for letting me know. I really want to move to MS, but it is going to come down to time and Challenge budget.

Thanks for the offer, but I'm not going to have room for that in our budget. The current thinking (as of last night's wrenching session) is that we are going to fabricate a divorced wastegate set up like this one:
http://i170.photobucket.com/albums/u...astegate-1.jpg

Hopefully that will improve flow dramatically on the cheap.

Woo to GRM 2008!

I should be down there with my buddies. Gutty from GRM 2007 will be back with some updates. I missed it last year, but have it on the books this year.

That's great news. But man, what a haul from Chi-town....

Let me know if there is anything I can do for you here in town in advance of your arrival. Or, if there is anything you need once in town, I can probably help there too.

I'd love to know more about your turbo set up. 230-250 rwhp is my eventual goal, even if after the Challenge.