Where does the Greddy TD04H-15G fit in?
 

I've been working on improving my spool on my TDO4H 15G. Latest upgrade has been the Bell Engineering divorced gases 2.5" downpipe. I've been comparing my spool with other's in the spool data thread and noticed that a lot of guys are spooling faster than myself.. though my setup still has some work to do, I'm wondering where this turbo that Greddy picked fits in compared to the lineup of Garett turbos. I've noticed a lot of the guys spooling so fast are running small snails - Sav gets crazy spool but only 230 whp from 16 psi for example... are the TDO4H's signicantly larger..? I know it takes only about 15 psi to hit 250 whp with this turbo...
I found a map of the turbo: http://www.stealth316.com/images/td04-15g-raw.gif
But I don't know how that compares to others..
-Ryan

what is the rest of your exhaust like? what do you have between the air filter and turbo, bends ect?

Compares to GT2554. But the Greddy flows slightly more.

Just like asked above, what size exhaust are you running? Is it crush-bent? Muffler type? That would be the best way to increase spool, to get a better flowing exhaust. That is why my exhaust goes straight back out the back. Only bends are around the diff, and those are minor. We moved the cam gears slightly to delay spooling for traction coming out of corners, and it still hits 10psi at 3800rpm. It was making it closer to 3k. You can also get a better designed manifold, but that is normally saved for bigger turbos ($$$).

Right now after the downpipe is a Magnaflow high-flow 2.5" cat and a magnaflow 2.25" cat-back exhaust which is mandrel bent not crush. It is not a 'turbo' exhaust so the muffler I am sure has baffles in it - exits out the normal passenger side spot in the bumper. I know this is not ideal, the biggest hurdle to overcome was the downpipe up to now as obviously the greddy dp is tiny, so I just replaced that with the BEGI one.
Ray - spool at 3k sounds orgasmic. I am aiming for every bit of spool for autocrosses. I run 9 inch wide Goodyear Eagle full slicks so I have the grip.

I am going to do a cut-out on the downpipe in the straight section just before the flex pipe. I can run it nice and quiet on the street when commuting so as to not draw attention (but still be quick) and then from in the cockpit with the flip of a switch I can go to a setup with maybe 2 ft. max of 2.5" downpipe and then a straight dump out to atmosphere - should be the most free flowing one could possibly achieve.

What's this about using the adjustable cam gears to alter spool? These are relatively inexpensive, could using these help me get more spool out of the car?

-Ryan

You can alter cam timing to change spool, but you'll get more from a free-flowing exhaust. For every change with the cams gears to add faster spool, you'll lose top end. Be careful with the dump, you might get unwanted boost spikes. For such a small turbo, spool is soo fast that you might not have enough, I'm gonna say it, the bad word for turbo people, exhaust backpressure.

I think I'm going to pull the cat off the car so the exhaust dumps straight out the car and see how well it improves spool vs. if it introduces any issues like boost spikes etc... I can set overboost just a hair over what I want it at so if it does want to spike the ecu will keep it from doing anything unsafe..

p.s. at what boost are you achieving the whp in your sig with?
nevermind, I see it was 10 psi according to your cardomain site... very nice numbers for 10 psi. Any secret ingredients that achieved that?

Whatever you do, I can't wait to see it in person when the autox season starts! When is that anyway?

Well, it's already started actually - I missed the first one which was the last weekend of Jan. There is another at the end of this month, you can see the UFO schedule here: NorCal UFO
Depending on how soon I get the injectors in and the weather (I swore off rainy autocrosses after the first season of chasing class points and attending each one rain or shine), I should be there. Even if I don't race for some reason I'll drop by as I did with the last one just to hang out. We'll see what happens as I get closer to that time.

.. I should just remove the cat and exhaust for race day... it's really just extra weight ;)

-Ryan

Koto, come out to the autocross school on the 21st of February. Not sure whether they've filled it or not. I'll be instructing.

What level boost are you running? Are you running the stock craptacular wastegate?

edit:

TD04H-15G can flow around 440CFM (275HP) 55 trim - 41.2mm in. - 55.55mm ex. | Turbine: 2.047" ex.
2554R can flow around 350CFM (220HP) 60 trim - 42mm in. - 54.3mm ex. | Turbine: 2.0866" ex.

Every dyno plot I've seen puts the spool characteristics and torque output more comparable to a T3 60 trim or 2560.

^^^^^^
What he said.

I was actually surprised to see the wheel sizes of those turbos so close to each other and NOT closer to a T3. But like i said, they perform like a larger turbo, I could put a lot of my dyno plots over a few greddy setups and they'll look identical.

In fact:
http://www.boostedmiata.com/dynos/scott_vs_phil.jpg

I wonder what the turbine A/R is? Really the only places it's bigger than the 2554 is a slightly larger exducer on the compressor wheel.

Dammit, I forgot which thread had the link and now that I found it again, school's full. I think I might come to the autox the next day, it's a bit cheaper anyway. Will y'all be there?

I'll be there Sunday as well, yeah.

Werd. Try not to laugh at my enormous silver OTM..

Thanks for that. I'd been looking around wondering how the 2 compared! :bowrofl:

Bumping this back up - the compressor map for the 15G that I meant to and seem to have failed to attach in my first post is here:
http://i175.photobucket.com/albums/w...15GFlowMap.gif
I was just looking at this and I have never actually known how these are read except that I know the center 'island' is the most efficient zone of the turbo (76% in this case) and surrounding rings are less and less efficiency.
The part I don't get is that I take it the y-axis is in BAR pressure?? If so, the compressor map doesn't even begin until 1.2 bar (17 psi) which obviously makes no sense.
While I'm already at it making myself seem the noob, I don't have a clue what the x-axis means...

If anyone could explain I'd appreciate it.

-Ryan

Standard atmospheric presure is 1 Bar, the graph illustrates that. In application the 14 psi/1Bar of boost would actually be 2 Bar ... 1 atmospheric + 1 boost.

:facepalm:

Can't believe I didn't realize that. Thanks.
Anyone want to enlighten me about the x-axis?