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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 12-31-2008, 08:10 PM   #21
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lets say I run a gt2554; it seems to me like that thing would be damn near insta-spool on my setup, so the wastegate would open pretty fast. Would I need to run an external wastegate to not choke things up on the top end?


it would help

search?
google?
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Old 12-31-2008, 08:11 PM   #22
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Seriously. Nobody on this forum can tell you what turbo to run. You have to decide what's best for your goals. It takes a lot of time/research to get a good grasp of what will work within your criteria. All anyone here can do is say "XX turbo for yy to zz HP, etc".

And FWIW, all the flow **** in the world will only help spool so much. You gotta remember the average pent roof DOHC engine (ie-your motor) has ~92% VE around peak torque, which you will surely be spooled by. You will never reach 100% efficiency, so everything in the world you do to increase flow is looking for that last 8%. IE-you won't see a 1K RPM decrease in spool time because of your setup from flow gains alone.

I'm gonna say put a GT2560 because it will spool 'well' and be "good for" 250-300whp. But that's just an opinion from someone on the internet who's never even seen one in real life, much less drove a miata with one.
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Old 12-31-2008, 08:19 PM   #23
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...has ~92% VE around peak torque, which you will surely be spooled by. You will never reach 100% efficiency, so everything in the world you do to increase flow is looking for that last 8%....
Thank you. I had no idea about that. That's basically what I was looking for with this thread.
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Old 12-31-2008, 09:04 PM   #24
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Quote:
Originally Posted by N3v View Post
lets say I run a gt2554; it seems to me like that thing would be damn near insta-spool on my setup, so the wastegate would open pretty fast. Would I need to run an external wastegate to not choke things up on the top end?
savington runs this turbo at 230whp on a 1.8 and it sees the track as much as anyone here.
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Old 12-31-2008, 09:09 PM   #25
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Basically, you fucked up and you've spent all this money on a slow, NA, ITB queen ride because you wanted to be cool and JDM. Now look at you, you're a bitch. You're also one of those morons who doesn't understand that "12psi of boost" from a pea-shooter turbo is different from a gt45r.
.
+1 That's just some dumb dumb questions you're asking.


why on EARTH do you care how many PSI you are running? I'll tell you what, put in some maxed out 750cc injectors, swap cams for something with a whole lot less duration, and I'm sure you can run 12 psi. At 57 horsepower. AT THE WHEELS!!!11!

The reason no one wants to talk about ******** is (with rare exception) the *******s know jack **** about how a car works.

11:1 is a joke. You're really better off without a turbo. You *HAVE* to pick a power goal.

It's like going to the walmart to get something "wrapped in plastic". Think about what you need first, in very, REAL terms. Then maybe someone can say something. Not being rude here, but you don't strike me as any tuning genius, so no one is going to recommend something you can "figure out" to you.

Do me a favor, show me a dynosheet for the monster you already are driving. The only real answer to your question is this: Buy a second motor, build it for a turbo. Then swap them. You'll have an IRTB set up, and you'll have a fast set up, you can use whichever you want without having all these losing compramises.
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Old 12-31-2008, 09:12 PM   #26
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I dont see mixing an n/a built engine with a turbo as a good idea. its doable for sure, but stupid imo.
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Old 12-31-2008, 09:30 PM   #27
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Seriously man, you have to take all this negativity with the best intentions. The motor in your car is the EXACT opposite of what you need for boost. It sounds like a fun setup don't get me wrong but, really, just buy a stock motor and do whatever you want to it but keep it efficient for boost purposes.

As far as turbo sizing it all depends on what you want. You need to SEARCH and ask around for people opinions on what they think their turbo is good for.

EX. I'm running a 2554 because I will be autocrossing every month and will need the instant spool. However, when I move to Orlando, and only drive on highways, I will switch to a 2871 and put my motor to good use.

Good luck man!
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Old 12-31-2008, 09:39 PM   #28
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now that everyone is dogpipiling this kid and trying to poz this unsuspecting neg, I have to say "you're learning now. Just stop posting the NA/******** ****, please."
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Old 12-31-2008, 09:40 PM   #29
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now that everyone is dogpipiling this kid and trying to poz this unsuspecting neg, I have to say "you're learning now. Just stop posting the NA/******** ****, please."
down like a clown charlie brown
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Old 12-31-2008, 10:05 PM   #30
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Run a 3071, With compression like that you should spool it very well and make good power per psi.

You can turbo a 11:1 motor. Most guys would be running alcohol w/ that compression ratio. But, with pump gas you better have a dead on tune. It won't be very forgiving.

Methanol Injection is a must on this car if you are running pump gas.

Consider running aftermarket cams w/ a tad bit more overlap to reduce the Dynamic Compression Ratio.
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Old 12-31-2008, 10:13 PM   #31
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Dynamic Compression Ratio.
Hey now, don't come in here using big words and fancy terminology for ideas that are not understood by the vast majority of the forum. That's a whole 'nother thread...
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Old 12-31-2008, 10:14 PM   #32
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And OMG you offered someone advice...
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Old 12-31-2008, 10:16 PM   #33
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And OMG you offered someone advice...
I know, don't get used to it
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Old 12-31-2008, 11:28 PM   #34
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I always try to find my answers on google as well as the forums before asking any questions. Here is what I found in like 5 minutes, and yes, it has been discussed on other forums before:

MotorSports Digest
Dyno results, high compression and E85! - E85Performance.net - Discussion Forum for All E85 Car Owners
High compression engines and boost - Honda-Acura.net
High Compression vs. High Boost – Superchevy.com Tech Talk Forum

What I take from the reading I just did is that 12psi on 93 octane and 11psi = smoking crack or **** poor ignition timing and no power gain. I say either get that thing running E85 and a gt30ish turbo and do the 12psi you want, or get the same turbo and stick to around 5-6psi ... which will still likely put you at 200whp, but at the ragged edge. WI might help, but only to a certain point.
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Old 12-31-2008, 11:54 PM   #35
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Did you not see the clever walmart comment? You don't go shopping for something red, you go shopping for something to play your BlueRay(tm)s. You need to pick a HP and ask how do I get there given these constraints (i.e. I want to run 11:1 or I am a huge retard with no more right to be on God's Green Earth than an impotent three toed sloth).

Don't say "I want to run 12 psi" cause what if 12 psi turns out to be the very worst number you could ever choose.

Please listen. Many of the people here are internal combustion engineers, work for NASA, or other such things. And then there's the folks who aren't even me. :-) Most of them are smart, too.
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Old 01-01-2009, 12:16 AM   #36
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You don't go shopping for something red...
Analogy Fail

(You're obviously not married.)
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Old 01-01-2009, 12:38 AM   #37
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EWGs are more important at low boost levels than at high boost levels.

(I am making these numbers up.)

To make 230whp on a 2554R, let's say you need to run about 15psi. 15psi is about 75% of the airflow of the motor through the wheel, and 25% through the wastegate.

At 6psi, you only need to run about 40% of the air through the wheel, which means 60% through the wastegate.

Thus you need more wastegate for lower power levels and less boost.
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Old 01-01-2009, 12:58 PM   #38
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Dude do you already have 11:1 cr, or are you about to build it?
If you haven't built it yet, forget it.

If you already have the motor built. I would try a thicker head gasket, and less boost. And mabe the cam settings the guy was talking about.


Futher more, CALL BEGI, tell them the setup you have, and they will tell you your limits.

They will help you decide what turbo you need, and what boost to run, for said hp.

DO not attemp this without talking to them and FM.
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Old 01-01-2009, 01:02 PM   #39
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Dude do you already have 11:1 cr, or are you about to build it?
reading comprehension ftl
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Old 01-01-2009, 01:12 PM   #40
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reading comprehension ftl
Yea, I just read over the first post again. Man that is high compression.
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