Striking out with the googles, i need specs of a turbo

Trying to find specs of the Garrett turbo that was on the Grand Nationals.

Anyone happen to know them, or where to find them? Google isn't helping a whole lot.

I may have found it.

internet said: I did some digging. In "The Source",for May/June 1994, there's a turbo comparison chart. The stock turbo for 86/87 was a Garrett TBO348. It had the .63 A/F, a 2.75" comp wheel, 1.950" inducer, and a 59mm turb wheel with 18mm blades.

With this knowledge, comparing against a Toyota CT26 turbo... what should i expect, those of you who are more versed in turbo specs than i am? (I just run... big ones)

ct26 data said: 35 lbs/min 1.811” inducer 2.559” exducer 2.185” avg. 1.97" Turbine minor 2.36" Turbine major

vs

noticing this is trim specific on the CT26, read more here and here

to me the CT26 "40" trim looks to be equal on the low range with slightly better top end performance across the broad pressure range, read the note in the TBO348 to understand why I say that, and is more efficient overall...

So you think the CT26 could actually be the stronger turbo here?

I have a Supra single entry CT26 with the larger housings, by the way, if that makes a difference. (Probably does) For some reason i thought it was a "44" trim, but i could be wrong. All i really know is that it spools with all the sublety of a dead blow hammer at 3000rpms, and gets downright stupid around 20psi.

I can't see the map right now for the GN turbo, it's blocked by websense at the moment.

Appreciate the input!

In reply to 92CelicaHalfTrac:

From what I can find GNs had 3.8L OHV V6s running 10psi of boost vs a Supras 7M-GTE 3.0L DOHC V6 running 7ish psi of boost . I'd buy that based on the engine size and head flow, though the 40 trim above may not be exactly what the 7M ran, I'm not sure. Next you would need engine flow numbers at various RPMs overlaying each plot. Then calculate your motor's flow numbers and overlay them...

I'm just trying to keep this back of the envelope.

You could also look at a Holset if you enjoy 'riding the wave', I certainly enjoy it

Well, the plus side of the GN setup that i'm currently looking at is that i would finally have a real T3 flanged manifold. Getting a Holset on there at that point would be cake.

But if it's no real performance advantage, i'll probably just buy it as backup, and/or pass it along to msdsm for his MX6 GT later.

From what you seem to be saying, the GN setup isn't going to offer any real advantage that would even make it worth bolting up.

Ok now that i'm home, i'm seeing the plot for the Garrett, and now i'm utterly lost.

Is the dotted line through the center of the Garrett map the same as the solid line through the CT26 map? What exactly does that line show? I see it referred to as "boost trace."

Barring the fact that the CT26 map goes to 3.2ish vs. 2.6 on the Garrett map, they look almost identical to me. They both seem to max out at 36-37lbs at 120krpms.

But i'm a noob at this... if i'm missing something, i'd be very thankful if you could learn me something.

In reply to 92CelicaHalfTrac:

The Garrett was only run up to 2.6 as per the comment, doesn't mean it can't go higher, the line represents some engine flow number at some RPM, that's why I said you have to do some calculations to get your engine's air flow numbers, that way you can map it out at various airflow/pressure ratios. You overlay that line on top of the flow map to see where your engine would be in terms of flow capability and what efficiency you'd get on the turbo. The instructions for doing is are here: http://www.gnttype.org/techarea/turbo/turboflow.html or http://www.turbofast.com.au/turbomap.html or http://www.lovehorsepower.com/joomla/index.php?option=com_content&view=article&id=4&Itemid=88

Yep, got that part, but the maps if you look at the CT26 only to 2.6, they still look just about the same.

I'm going to check out those other links today, i don't think anyone has ever gotten these numbers for this motor. Could be fun.

Now, i did track down someone who ran this turbo on an F2T. At 18-19psi at high elevation with some massive exhaust leaks he still made 298whp.

Will try to get ahold of numbers and report back. Wish i could find a map for the bigger single entry CT26, though.

Oh this makes me unhappy.

More bullE36 M3 proprietary flange action, huh? For some reason i thought this was a T3 flanged hotside.

Oops, missed this thread.

The GN wheel is 50/70 mm inducer/exducer on the compressor side. Im sure you've seen or can find what GNs CAN run on a stock turbo.

IMO based on the inducer/exducer diameters you posted for the ct26, the GN turbo is not a big enough upgrade to justify the effort, and that's not even considering that it doesn't just bolt on.

That's about what i think i decided... still trying to play with numbers just for fun, though.

I'm still buying the setup, because it makes for a nice backup, considering it comes with manifold and everything. I'd just have to adapt my exhaust to work with the turbo, but that should be simple.

It's likely that the GN setup will end up on msdsm's car for $2012.

My main sadness is that i didn't know that it wasn't a normal T3 flange.

Well, if it's a 59mm inducer on the turbine it's probably a normal garrett stg1 turbine so it will go into some factory t3 housings like a .48 chrysler or a .48 or .63 ford housing. The ford housing has the normal t3 pattern on it. Chrysler is closer to a t4 pattern but if it's a custom app that may not matter.

Vigo wrote: Well, if it's a 59mm inducer on the turbine it's probably a normal garrett stg1 turbine so it will go into some factory t3 housings like a .48 chrysler or a .48 or .63 ford housing. The ford housing has the normal t3 pattern on it. Chrysler is closer to a t4 pattern but if it's a custom app that may not matter.

This is coming back to me now... The guy that ran this had a ford housing on his.

The turbo is what makes me mad with the flange style, it's the manifold. I was hoping to use this manifold with a holset or some other more modern turbo down the road if i kept it.

But i suppose that hacking it off and having another welded on wouldn't be terrible since it wouldn't be the cast iron stock monstrosity at that point.

Mine!