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Old 12-19-2008, 03:17 PM   #1
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Default Power estimate...

So for right now I am running a stock 99 motor, SR20 turbo, small intercooler, and MS1 parallel with stock injectors. In a few weeks I hope to install my 460cc rx-7 injectors and run like 12-14 psi. This setup will be ideal for me for this year.
Next year I want to go over my motor, cause I know as of right now, my rings will be toast. I want to do a +1mm overbore, and install FM turbo pistons and rings, and run stock rods. ATI superdamper and a bigger intercooler also. My question is this...
I want run the maximum limit on the 460cc injectors. What that limit? What turbo should I use? and how much boost should I run to achieve this? I was thinking a GT2560 at around 15 psi. As far as I know my SR20 turbo will be at the max efficiency range on 14 psi, and aside from that, I can run the same boost on a GT2560 and make more power.
I am just curious what turbo to use and what boost to run. I like to drag race my car a lot, and I want it to be a consistent 12 second runner. At the same time, I drive it everyday; it's actually my "work beater." I read somewhere that 460cc injectors supply enough fuel for just under 300hp, I'm guessing that's at the flywheel. My car at 7psi I'm estimating is around 190 rwhp...and it's a blast to drive. So I'm sure that the 460cc injector limit (265 rwhp?) would be more than enough for my daily driver.
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Old 12-19-2008, 04:43 PM   #2
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cause I know as of right now, my rings will be toast. I want to do a +1mm overbore, and install FM turbo pistons and rings, and run stock rods.

Thirdgen; it's not like I'm the most qualified forum member on this subject but; I think I should at least call your attention about that part of your post. From what I've read on the subject, there is a general consensus around Miata owners that the rods are the weakest link on our engines. I would suggest that if you're going to do all the other things you mention; you should get stronger rods.

Just my 2 cents.
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Old 12-19-2008, 04:54 PM   #3
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Here's what you do, install the bigger injectors first and get it running good. Then start turning up the boost, while tuning the ECU to mantain a 12:1 or richer AF till you hit 80% duty cycle on your new bigger injectors. Then back down the boost a PSI or 2 and go dyno for the WHP and TQ. This will give you a good indication of the limit of your injectors and turbo. See what IAT is at full boost to see if you need a bigger IC. Otherwise more changes = more downtime and potentially more problems.
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Old 12-19-2008, 05:18 PM   #4
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Read the DIY FAQ and do the math to find out what your injectors will support.
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Old 12-19-2008, 06:34 PM   #5
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If you have the engine apart to do rings, definetly upgrade rods and with the overbore pistons. With it apart why stick with the 460's? It would be a minor expense and hassle to go with something bigger. Cleaned 550's are $125-$150 all day. Cheaper if you look hard.

With the expense and trouble of going through the motor it doesn't make sense to me to let the injectors you have now be the limiting factor!
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Old 12-20-2008, 02:02 PM   #6
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Good deal, I guess go big or don't go at all. So let's say I did rods and ran 550cc injectors. Would a GT2860 at like 18-20 psi be a good combo for this setup? Like I said before, I want to keep it a daily driver, and if I am running this kind of boost, I won't use it all the time. Just would like to know it's there if I need it. I just don't think I can imagine a 300+ hp daily driven miata. Guess I should find out?
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Old 12-20-2008, 02:42 PM   #7
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I've seen cars gain 40whp from spark tuning. Guessing is irrelevant.
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Old 12-20-2008, 05:50 PM   #8
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Good deal, I guess go big or don't go at all. So let's say I did rods and ran 550cc injectors. Would a GT2860 at like 18-20 psi be a good combo for this setup? Like I said before, I want to keep it a daily driver, and if I am running this kind of boost, I won't use it all the time. Just would like to know it's there if I need it. I just don't think I can imagine a 300+ hp daily driven miata. Guess I should find out?
I'd have to look at a turbo map to figure the result of a 2860 at 18-20, however, stronger rods and 550s should be safe with that combo.
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Old 12-20-2008, 06:34 PM   #9
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I'd have to look at a turbo map to figure the result of a 2860 at 18-20, however, stronger rods and 550s should be safe with that combo.
my car has rods, pistons, 550's, a gt2860rs, and will hopefully hit the dyno next week. I told Corky to not take it over 301whp on the dyno...but to put the boost controller at 250whp when they give it back. We'll know soon.

Originally I thought that turbo would be too big. However, even with my garbage spark-map I made 10psi at 3600rpm, so that's low enough for my goals.
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Old 12-20-2008, 08:54 PM   #10
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Hey Hustler, what day next week? I will be at the dyno on Tuesday morning and they mentioned another car was lined up after mine.
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Old 12-21-2008, 12:00 PM   #11
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Hey Hustler, what day next week? I will be at the dyno on Tuesday morning and they mentioned another car was lined up after mine.
I don't know what they have scheduled. I did the "call me when the car is done or you need some money" thing. You should definitely get a dyno vid or at least a pic of my car green car though, and post it here.
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Old 12-21-2008, 06:47 PM   #12
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Hustler check your PM
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