stokEd

iTrader: (3)

The stock turbo reaches peak boost around ~3000 rpm and begins to taper around 5500 rpm, yes. Both the turbo and the tune (programming) are responsible. The stock turbo can be tuned to hold more than 14 psi at redline, but it is phyiscally unable to move enough air to maintain peak boost until then--and thus why people upgrade to "bigger" turbos.

This graph posted before sums up the stock turbo pretty well:



Boost is higher than stock but the same rules apply.

Robevo RS

iTrader: (16)

small turbos going to have quicker spool so lower rpm power , but running out of breath on a high rpm. The bigger is opposite. Has higher rpm power but suffers at the lower rpm. Bigger is not always better. You have to check what you do and pick the turbo for that.
In our rally car the engine basically runs as a N/A engine after 5500 rpm. No more turbo help. But at low rpm gives a great tq to propel the car out of turns. Mean while the drag set up turbo is lacking the low rpm power , but shines at the high rpm where the drag car engine runs.

BluEvo210

I also thought the peak boost was about 21psi or 1.5bar. Is that right?

I saw in a magazine where they had a dyno chart of an Evo before and after the installation of a GT3071R turbocharger. It showed that my stock Evo makes about 50hp (maybe less) at 2000rpm, which explains it's kinda hard to get a smooth start facing uphill are such a pain in the @$$.

All the articles to mention the Garrett GT3071R talked a good game about this turbo spooling up really quickly. The article with the dyno graph also showed the modified car to make less power than stock up to 3500rpm. It would make my car useless for the drive to work!

I'd like to get a downpipe with a divorced wastegate design, a cat-back exhaust, and a tuned ECU. That stuff should help my power and response throughout the rev range, right?

If I wanted to mess with the turbo, is there anything I could do with it to help the response right off of idle? That 50hp at 2000rpm? Or do I just have to keep it stock?

murlo26

iTrader: (9)

^Yes, mivec tuning will spool faster than the stock spool.

E6-X

iTrader: (4)

small turbo = quick spool but tq drops quickly needs > boost
big turbo = slow spool but tq holds needs < boost
higher ign timing = > tq
leaner afr's = > hp

BluEvo210

Is there another thread that talks about this? I've looked and haven't found it.

chkmgnt59

iTrader: (3)

there are hundreds of threads you should be reading and understanding before you go buying any mods for your car. you need to figure out what type of driving you're doing, and then build it to there. Do you track your car? Do you even know what a completely stock evo is capable of? Or are you blindly obsedded with a torque curve tapering off without having a clue what torque really is, or why it doesn't matter that its tapering, so long as HP is still rising? Or that my previous statement completely and totally depends on what type of driving you do.

This place is a wealth of info, but you seem to have not looked at all.

BluEvo210

The threads I've found comparing different turbos are mostly comparing turbos much bigger than stock. I keep hoping for an exception, and in a zillion hours of reading I haven't found it.

"Does a 6262 lag more than a GT42?" I don't care. I want to keep my low-rpm response for daily driving, and I want to keep my midrange response for digging out of corners on an autocross course, where high rpm counts for about a second at a time.

...but I guess the fact that you don't know me counts for more than my engineering background or my autocross trophies.

murlo26

iTrader: (9)

Get a v8 and put it in a miata...you seem like that type.

BluEvo210

You have no idea... I'm trying to talk a friend into it now.
He likes Miatas, and can do the swap himself.
He mostly needs spousal consent.

murlo26

iTrader: (9)

v8 miatas are full of win

Happy wife = happy life...from what I hear, so he better get the consent.

Saw this one a few months ago...

Sharkbite2000

iTrader: (21)

Want more TQ get a bigger turbo

P.S. + a 2.3L with help a great deal in spooling a bigger turbo.

chkmgnt59

iTrader: (3)

If you auto-x, stock turbo or maybe a green are all you want. youre not moving fast enough for a red or larger to help you. You also have to worry about staying in your class, so you cant do anything really to help hold power other than a 3-port