thirdgen

iTrader: (26)

So this year is a busy one for me, as I am getting married in July, and I have a lot of home renovations to do, etc. I am planning on pulling my engine at the end of the year and doing some things to it that it needs. The compression numbers are low, which is normal considering it has 142,000 miles on it. It burns oil, so I'm planning on honing it, getting new rings, and most likely getting the head overhauled with new valve guides, etc.
So here's my question.
I am running a stock SR20 turbo, and I have a full 2.5" exhaust. When my car dyno'd last, it made 209 whp at 11.9psi with a STOCK midpipe and a MS-1 running parallel with a '97 CAS. It also blew smoke all over the place. I have since upgraded to a stand alone MS-II and I can say that my car is running a night and day difference of better. So with low compression numbers, a stock SR20 turbo, about 12 psi, a shitty exhaust, and a stock clutch, I made 209. After I hone and re-ring, and have G-pop shop bore my compressor housing to accept a 60 trim wheel, put in an FM Level 1 clutch, and now I have a full 2.5" exhaust...What do you think I'll put down to the wheels at 14psi?
I need to know a few things like...Will my 460's be sufficient? What 1/4 mile time do you think a setup like this should run? Will my 2.5" exhaust be ideal, or should I really run 3"? If I do need 3" exhaust, how much gain should I expect over my current exhaust? I.E. Would a 3" setup really be worth the money for a daily driven street car?

thirdgen

iTrader: (26)

I'm shooting for at least 240 rwhp by 12 psi, and at least a 12.9 second 1/4 mile time. Think I'll do it?

dustinb

Hmmm it's tough to say. I was only putting down 186 HP, but 218ft/lbs of torque on my last T25 setup (smaller then sr20), and I couldn't run faster then 14.4 seconds. The big problem was that my power band was all at the bottom, and nothing at top. It was great for 60ft times, but that's about it. If you want to get into the 12's, I really think you need to get a bigger turbo. Something like the GT2860 or even 2560 would be ideal. I'm pretty sure even with that wheel upgrade on the SR20 T25 you're still going to drop off quite a bit in the top end.

18psi

iTrader: (76)

Let me give you some VERY GOOD advice that was given to me when I was rebuilding: rebuilding and keeping stock rods is just dumb......

That sr20 t25 should definitely be able to get you to 12.9, though probably not much faster. Its a small turbo after all. I'd get something bigger though. You have a 1.8 and a well flowing head: take advantage of that.

Just my .02

flier129

iTrader: (7)

+1

Speaking of which, I've got some Crower rods that need a refurbish that I'd let you have for cheap

thirdgen

iTrader: (26)

So if I used my pistons and honed / re-ringed, but went with a tuffer set of rods, I should have a stronger rotating assembly. They say that the sr20 turbo with a 60 trim wheel is compared to a GT2560...would my 2.5" exhaust be suffice?

18psi

iTrader: (76)

its a small turbo. even with a slightly upgraded wheel its still a small turbo. Why not get something better suited for your goals of 240whp? and I had no problem getting to ~250whp on my previous setup with the 2.5" exhaust so I dont' imagine you having em either.

Though 3" will make more power

thirdgen

iTrader: (26)

What turbo did your previous setup have? If I'd ever change my turbo I'd probably go with a GT2871. Still, I bought all my exhaust new, it's stainless, and I really like how the car sounds so I don't really wanna swap exhaust and spend the money unless there's big power I'd miss out on. Keep in mind my car needs to remain a very dependable daily driver...

18psi

iTrader: (76)

It was an HKS ball bearing equivelant of a 2871. It was GREAT for street use. Absolutely loved the powerband, and I'm sure it could have handled way more than 250whp

shlammed

iTrader: (8)

your missing out on big power with 2.5 inch exhaust.
you might be able to hit those numbers on a high-reading dyno on an SRt25... but not on a low reading dyno.

12.9 seems fast for a street trim miata on a small turbo.

Get a bigger turbo, they are fun and will make the power you want... the SR T25 is piddly little thing and isnt worth modifing...

your engine would flow more than my 1.6, so with a 2860 you should be in the 225-250 range at 10-12psi, and have full boost around 33-3500rpm.


Also, toss both pistons and rings into the engine... the new pistons will take to the heat and added stress better than the stock pistons. i wouldnt bother doing rods but no pistons... but that is just me.

18psi

iTrader: (76)

completely disagree
in fact I did just that: put in OEM (lower comp though) 9.1:1 pistions and upgraded rods. so far nothing but great results and very satisfied

shuiend

iTrader: (24)

Thirdgen, Check with G-Pop Shop about the over boring your turbo. I talked to them about doing mine and was quoted at around $700. Might be cheaper just to sell yours and find a 2560 for sale. Also if you are going inside the engine get rods.

Sparetire

Regarding the 1/4 ET, I ran a 12.99 in a 3000LB car with mid-high 200s WHP on a 1.7 60' that was on 4.10 gears and 205/60/16 tires. It doesnt take much to get a 2400ish LB car there on 4.3 gears and 225/45/15 or so tires. These cars dont seem to run good ETs, but thats not because of power, its because of setup and drivers who generally dont give a hoot about drag racing compared to HPDEs and autox. If you can get that same TQ to hold on at higher revs (my guess is that your TQ plunges at about 5.5K RPM to have such a low HP number) and cut a good 60 you will see your 12 even with a tiny T25. A T28 would be worlds better though, and much more capable of holding TQ to redline. I would also look at adjustable cam gears to just setting the timing back 1 tooth for more top end. Above all, ditch that mid pipe. The 2.5" means next to nothing with that POS in there. You dont really need more power, you just need a good 60 and less TQ loss past 5500. My guess is that the mid-pipe is a huge part of why you are loosing the TQ. Back pressure kills flow.

thirdgen

iTrader: (26)

So I'm thinking this. Upgrade rods, hone block, re-ring. Use STOCK pistons. Upgrade to GT2871, I'm thinking I will need 550c injectors as my 460's probably won't cut it. Think I'll need to upgrade my intercooler? It's the old FM intercooler setup with the tanks on the top and bottom. The metal intercooler piping measures about 1 7/8" ID, with the exception of the piece that goes to the throttle body.
All I really want to do is make 250whp EASILY by 12psi without changing my exhaust.

18psi

iTrader: (76)

I'm fairly certain the 460's should get you to 250 no problem. definitely get an ebay intercooler kit, they're cheap and easy set up. otherwise sounds like a plan. At least to me

thirdgen

iTrader: (26)

Hey Spare, you said ditch that midpipe, are you talking about the 2.5" one I have on now? Cause I ditched the stock one over a year ago and don't even miss it.

Sparetire

Ah, OK, good. So you have 2.5 all the way back, my bad. IME 2.5 flows enough for a pretty retarded amount of power. Other cars out there have made well over 350WHP with 2.5 exhausts. 3 would help spool.

The 2871 will move a ton more air, I dunno about doing 250 at 12psi though. Sav would be a great source of info on that, IIRC he was right around 260WHP on a 28XX for a time at a pretty low pressure ratio.

As far as IC pipes, I have always looked at what my TB is like. I love seeing 3" IC pipes on a Tb thats like 2". Usually a 2.5" IC pipe packages well and flows more than any of us will need. I dunno about a 1 7/8.

viperormiata

iTrader: (24)

No need to replace it. It is a great intercooler, just upgrade the pipes. I used some of my friends extra ebay aluminum 2.5" peices and made a new setup in just a few hours.

thirdgen

iTrader: (26)

Awesome! Thanks. Now on to injectors...
I was thinking about rx7 550's, but I found a set of deutschwerks 600's. Those should work with ms, right? What is the impedence as compare to my rx7 460's? They are pnp for a 99 miata, right?

thirdgen

iTrader: (26)

I just searched and they are high imp so disreguard that...But they will fit my 99 with no modification right?