And so it began with my purchase of MODRX7's A-Spec GT40R kit and a preemptive retainer with a brutally reputable divorce attorney to keep my chick from dumping me. About a "G" after the initial purchase (hi Edan!), I'm down to the ceramic re-coating to finish it up the kit.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>

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While I had the turbo apart, I decided to snap a few pictures to clarify the compressor wheel dimensions. Here's what ye ole trusty Starett calipers gave me:<o:p></o:p>

• Compressor (88mm): Inducer 3.48" / 88.4mm
  Exducer 2.47" / 62.7mm<o:p></o:p>
• Turbine (GTQ): Inducer 3.05" / 77.5mm
  Exducer 2.67" / 67.8mm<o:p></o:p>

<o:p></o:p>
Anyways, we'll see what I can bring to the table for the clan of the GT40R masochisists. Certainly ALL of the pieces will be in place in my car's setup (I know Jimbo, except the LS1), so it's just up to the design and my tuning now (or atleast in a couple of weeks when I get the plumbing back from the coating shop). Should be fun over the next month or so... !

So stay tuned.... same "Bat" Forum , same "Bat" Garrett!<o:p></o:p>

 

A "Tear Hits the Keyboard"... (as I remember the good times I had holding her(the turbo) tight as we cuddled the night away).

I never understood the dimensions of the turbo. I wish Garret would have listed the exducer, the actual size of the wheel.

Good Luck.

Edan

 

I thought the inducer was the small side and the exducer the larger side?

 

yes i think he accidently flipped it around!

 

FWIW, a digital caliper is ~14.97 @ Harbor freight. Thanks for the look see.

 

Thanks guys. Yes, I screwed those dimensions up. In fact, the inducer = minor diameter and exducer = major diameter. I knew all that acid from the 70's would be surface again some day!

Hey Carl, had a couple of the HB calipers, and though they lasted several years, I figured I'd throw some money and try an establish design. So far 5 years and counting one the calipers in the picture. Figure if they make it a another few years, I'll be at the break even point.

 

Yea, I find it humorous that Garrett switched and started giving the exducer spec instead of the inducer spec like they used to. Just goes to show how eager they are to fit into todays "bigger is better" metality and to give the GT series the appearance that its much bigger with the same spool as compared to thier old turbos so they can stimulate sales and charge more money. In fact the GT series and the older Garrets are all very similar in size, spool, and power. Its just that the GT series costs a lot more.

 

BINGO! Marketing genius, eh? Good example includes dyno results among massively hyped GT35Rs versus the "old school" T04S.

Most, if not all, of the compressor maps I've seen show about a 2-4% improvement in efficiency compared to their older models. I see little or no improvements on the hot side. If you plug this into some fancy equations, you notice that a 5% improvement in compressor efficiency is worth about 2 HP on a 450 HP rotary (using an realistic value of 80% for intercooler efficiency)!


Gene

 

Congratulations, man! What are you using for engine management? I KNOW you've enough fuel

Gene

 

I find this really hard to believe. Does that also mean we can run our turbos way out of their sweet spots at 55% efficiency and only lose 20 HP? It seems like something is not being accounted for in that analysis. Since I don't know how to quantify the effect of increasing the backpressure very accurately, I suspect that is what is missing. I don't think IC outlet temps tell the whole story here.

-Max

 

No, but good theory.

Remember a turbocharger's response is nonlinear. Within the efficiency "island" (what you typically see on a compressor map) you don't gain as much HP as you might think going from, say, 72% to 77%. Outside of the map, it's a different story altogether. Also worth mentioning that these maps merely show isolines, i.e., interpolated lines connecting similar efficiencies. If you could plot thes in 3D and rotate on a z-axis they would look like a hill.

The effect is, of course, further diminished by intercooling. Finally there is the hot side issue (turbine efficiency and backpressure). Interesting thing here is that, while you might be operating in the compressors ideal efficiency range, you might not be in the turbine's.

My point is that these turbos are better today than those developed 10 years ago, but not by a large margin.

Gene

 

Therewas an article in SCC aseveral months back, and garrett provided some hype to them that showed improvements in the range of 10-15% IIRC. Of course that was for designs not released to "the public" LOL

 

Of course

I recall reading about Garrett's widly efficient CART turbos a while back. Supposedly much of this technology went into their production line, but that may be marketing hype as well. At any rate, it appears to be working for them. Heck, I've one on my car too.

Gene

 

Carlos you're such a bad boy!

Are we going to see you in June?



Crispy

 

Got my June confirmation last week, so barring the annoyingly recurrant car/scheduling/deployment obstacle, I'll be there with bells on!

BTW, having Max, Gene and Crispy contributing to my thread makes my oh so very proud. The three of you have my utmost respect. Needless to say, I look forward to your continued contribution(s).

Sycophanitcally Yours,
Carlos

 

Wha? It's the other way around , dude

Gene

 

Ready to drive and tune it. After shakedown, I'll just need to ceramic coat the rest of downpipe, coat the turbo exhaust housing and install a turbo blanket.

My sincerest thanks to A-Spec for an excellent kit. Even my fab guy, who I have the upmost respect for when it comes to making anything with a torch, said he was impressed with the workmanship obvious in the kit.

BTW, the mods to the A-Spec GT40R kit include a 3" -> 4" Burns swage to allow terminating the downpipe in an HKS 4" v-band so it would properly mate to my HKS 4" exhaust. A TiAL 44mm WG was fab'ed into the manifold, along with twin EGT bungs (only using one currently). Finally, all of the plumbing (except for the hot sections) was ceramic coated by Airborn.

 

Just a few more for the inquiring minds, including some details of my Craig Davies Elelctric Water Pump (EWP) setup.

Thanks for humoring my rotary narcissism:

 

I love that "Catch Can"

 

Very nice, looks like you took your time putting it together. Nice catch can, did you get it on Ebay..? ;-)

 

That looks great, Carlos. That car is going to be awesome.

-Max

 

Wow that looks unbelievable!

 

Oooo...more inspiration for my engine bay. Looks sweet! Does that water pump come with everything to replace the stocker (meaning everything other than the pump itself)?

 

Thanks for the compliment, Max. My only concern after this many years playing with these masochistic obsessions is that pretty doesn't always yield the numbers. In foolish optimism, I've got my fingers crossed AGAIN!

Don't I wish that the EWP came with everything!.
Literally the only piece that is original is the pump itself. There is not a single component that was not custom fab'ed, include the aluminum inlet/outlet to the water pump. The original ones were plastic hose ends. I need an AN fitting end, and besides the plastic was determine to be a probabley long-term failure point.

For those of you that like my catch can, wait till you see my coolant overflow... can you say, "Black & Tan!"

 

awesome setup man...