Spic Racer GT40R
 

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>

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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

Initial install complete...
 

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" :beerchug:

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

That looks great, Carlos. :D 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!. :banghead:
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!" :beer:

awesome setup man...

Carlos looks good... I'm glad you did something that I couldn't...

Nice Job

-Edan

Don't I wish that the EWP came with everything!. :banghead:
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.\


Looking forward to a review of the waterpump setup, having at least a
secondary electric pump is something I want on my cars.


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


Better be careful - you'll give the troopers a reason to bust you if they pull you
over - "Hey, he's got an open can of beer in there!" ;)

Carlos, here's to having it run like it looks...

David

I would keep a close eye on that pump. They are known to have a short lifespan. I'm sure that's not what you want to hear but it is the main reason I went with a CSR.

Looks great , very nice work . I have a question though , shouldn't the hot (less dense) water from the motor go to the top of the radiator , flown down through it to be cooled and collect in the lower tank from where it is cooler and denser . The water is then pulled by the pump and discharged into the engine ?.

Hey Carlos, you have any good pics of your alt relocation? EVerything looks awesome man!!!

At a $140 you could buy a few of them for the CSR and change them out. They do come with a 2 year warranty.

I know exactly someone who did that. Went through three of them. My CSR wasn't THAT expensive. Besides I don't know about you but I'm not wanting to wonder where and when or what I may overheat. If he runs the pump binary it may work better but running it variable will burn it up.

This is true, but what sucks is possibally changing the engine along with it lol

That wouldnt make it so financially appealing hehe

Stephen

Sorry guys, but I've been swamped at work so I'll try and play catch-up:

SEAN: Though the Davies Craig Electric Water Pumps (EWP) are rate at 2000 hour (with the 2 year warranty), it is at 12v continous. I have heard of people "out there" that have had failure of the EWP. However, a few facts that put me at ease about the pumps' real world durability:

1. I use the EWP controller and have extensively recorded the voltage and cycles MY pump operates at. With the proper resistor inline, I'm able to control my temp between 174 and 195. This is also the temps that I have my fan come on and off at. At 174F the EWP Controller is putting out it's min duty cycle of 3.5v cycled on and off at aproximately 1-2 second intervals. At 190F, the controller is only puting out 9.0v continuous. If I had to make an estimate, I'd say I usually run right at 180F on the highway, 180-190F in the city and on tracks. My point is that the EWP Controller substantially reduces the pumps output by providing optimal power to the pump and no more. I wonder how many of those that failed were either wired for continuous full voltage to the pump or had a binary (traditional) temp switch. Either of these would work the pump significantly more than it was designed for.

2. I do give (perhaps too much) credit to the fact that ProDrive has been using the same EWP for years. It was in their LeMans winning 550 Maranello from a couple of years ago. I have the near admiration for the engineering aptitude of the company and suspect that they would not compromise the design integrity of their premier effort with a less than optimal product. That said, I do realize that a 24 hour race is world's away from the rated MTBF for the EWP.

3. I bought and keep around an extra one! ;)

It sort of tough to compare systems, though I'm confident that I have one of the most robust coolant systems on any rotary. In a lot of way, it was one of the original design center pieces for the car. Even with a front mount IC, the car has never shown even a glimmer of coolant system discrepancy in the Florida summer (knocking on wood). I have looked at other electric water pumps. If they had been readily availble several years ago when this process started, it might have made a different choice, though I'm not sure. As it was, the pump had to be purchased from overseas (Demon Tweeks) because there were no suitable source(s) back here in the States.

MARCEL: Your right about the convective nature of coolant in a radiator. However, after a discussion with C&R, who custom built the radiator, they though the inefficiency insignificant at the expect flow rate. Packaging the components in the engine bay trumped the marginal cooling inefficiency.

STEPHEN: Just a couple of pictures and not that great at that. It is a somewhat complicated bracket that uses some of the PS/AC bracket mounting points. The black powder coating is for sheer bling. I also threw in the DC EWP Controller picture cause I already had it in taken.

Thanks to all of the feedback. I do very much appreciate it... os keep it coming. It can only encourage me to share more...

EDIT: Should have taken a better look at the orientation of the pictures before I uploaded... sorry.

I'm looking forward to riding in that finely polished piece of garage art this weekend. I'll bring the worlds fasted TD06-20g turboed RX7 so you'll have something to chase.

HUGS :-)

FYI, the techline turbo X coating came in yesterday...go figure

Carlos, the people I spoke of used the pump controller as well. They also compete. Prodrive makes nice cars as well! I'm not saying your stuff wont work, just be careful it was the varying voltage to the pump that shortened the motor life on the pump. I wanted to use that pump as well, I just seen a few people have bad experiences with it. Hopefully you will not in which case I may switch mine out for yours ;) since that pump was my first choice. PLease keep us informed.

I´m installing the DC EWP on my car, and there is alot of parts that need to be manufactured to make it fit... this one for example!

And Carlos, your car looks amazing!!

Hey I make those!! Anytime you switch out the pump there is a lot no doubt.

Wow, that really looks nice Carlos!!

Could you list the parts that you had to fab for the EWP? I would like to know just how much stuff I'll have to make before I buy the pump. Thanks in advance.

Zach

You do?! I wish I had known that, before my "tool shop friend" made this one!
I think I´ll use the OMP block off plate to mount the pump at, and the alt relocation is at the drawing table right now...

Boy, it's amazing what a Cuban with a pair of vise grips can do :). Lookin' good buddy!

Gotta love all the button-head fasteners too :).

Keep up the good work! Hopefully I'll see you at the BBQ end of the month.

Dale

Please post more pics men , the car is incredible.

Did you use a inlet oil restrictor for install the gt40r in the RX7?

KG Parts sells them, too:
http://kgparts.com/jay-tech.htm

-Max

Thanks Dale. But it's a REALLY nice set of Snap-on vicegrips!! REALLY hope to see ya at the BBQ, though I realize it's a long drive.

JoeRoA: Gracias. Anything in particular you'd like to see in pictures. I need to take pictures of the exterior with the with the new (M2) wing. I'll probabley do that this weekend.

Rexset: The turbo has an integral restrictor insider the oil inlet, so no additional restricor was use.

The first runs were very encouraging. In 4th gear, I was seeing max boost by 4200 RPM. As several have mentioned, the larger exhaust housing seem to make throttle response below boost threshold much crisper, though the boost doesn't come on quite as quickly. I've taken three datalog off of the E6K, but only reviewed them for A/F, coolant and air intake. I'll need to go back and check boost response.

Long story made short: so far so good.

So far I'm delighted with the GT40R's performance. Getting addicted to the siren's call to speed from the anti-surge housing's whistle!

Boost pattern/threshold during today's 19 psi tuning run in 4th gear (low 80F conditions):

RPM MAP INTERVAL

4080 10.1 00:02.8
4080 9.2 00:02.9
4140 10.1 00:03.0
4140 11.2 00:03.1
4200 13.9 00:03.2
4260 13.9 00:03.3
4260 14.8 00:03.5
4320 16.5 00:03.6
4400 18.6 00:03.7
4460 19.2 00:03.8

Hope to get it on the dyno in less than three weeks. Even in current tune it's impressive... but only the number will tell the unbiased story.

Deficiencies: I need to correct an inordinately high injector duty cycle. Initial troubleshooting points to low voltage at the secondary pump (Aeromotive A1000), a result of crappy wiring on my part. Will confirm suspected fuel pressure drop before I begin the annoying job of rewiring both fuel pumps. :banghead:

Dyno "puddin' "
 

So here's "the pudding" (as in "the proof is in..." ) :

I'm very happy with the turbo's performance in specific and the car's in general. I'm especially delighted with the area under the curve (flat and broad).

TURBO:
- Graphs include only four of the seven runs I did in the 23 minutes total I was on the dyno.
- Beautiful Florida temps noted on the graph.
- First runs were off-the-chart rich.
- Bottom run show some of the rich stumble at the top.
- Air intake rose 68F degrees due to heat soak by the last run. Guess the ceramic coating, heat wrap and turbo blanket can only do so much!
- All runs with fuel spec'ed at an average of 96 octance and a specific gravity of .75 .
- EGT (max) sensed in the rear manifold runner located two inches from the rear exhaust port: 875C .

Subsequent to the dyno, I've tweaked the maps in the 7-7.5K RPM range to bring the AFR down about .5 and bumped up the acceleration enrichment to flatten the 4K spike at WOT.

I suspect that runs up to 25 psi will yield more power according to the increasing output in light of off-setting Intake Temp increase. I'll fuel-up with straight 104 unleaded and give it a go, but that will not be until after VIR in June. Definintely look forward to seeing the output with more reasonable intake temps at the turbo's efficiency edge.

COOLANT/OIL SYSTEMS: Even with the marginal fans provided by the shop, the coolant never got above 205F, and the oil temps shadowed the coolant temps by 5-7F degrees. Needless to say, I've check the success box with regards to this aspect of the engine's design.

IGNITION: These runs were performed with stock ignition coils and ignitors, but BR10EIX plugs in all four positions. I'd point to a properly wired ignition system with the correct dwell times set in the Haltech as the reason for the ignition system's flawless performance.

Many thanks to DRC for his invaluable help as my cohort in all thing rotary and fiscally irresponsible (an oymoron I think!):beerchug:

Nice
 

Carlos,

Nice write up and nice results!

What was your timing at peak HP? Thinking you have about ~20 more HP there if at 19psi? What was your boost level? Earlier post suggests 19.2 psi?

Also, you getting any crankcase ventilation issues? How are you vented?

Btw, the whistle from the bleed slot really gets addicting after awhile!

Tony

Hey Tony,

The boost levels for the individual runs are listed next to the legend on the dyno sheet. They were 16.5, 18.5 and 20.5. Though the boost controller and guage indicate steady boost, the Haltech logged a boost variance of of approximately -1.5 to +1.0 psi. Not sure if it's a sensor, or manifold signal source location problem, but I'm looking into it. ANy suggestions/insight is welcomed.

My timing was 15, 14 and 13 respectively. Split drops to 5 at 15 psi and then ramps back up to 15 at 20psi.

I have had no crankcase ventilation problems. I run a -10 hose off of the the stock oil fill pipe. I removed the plastic clip with the two barbs that the stock hoses connect to, tapped the filler pipe for a 3/8NPT to -10 90degree fitting and then ran the Earls SS hose to my "keeping-a-sense-of-humor" Guinness catchcan.

BTW, I was going over my datalogs last night and found that the intake temps had actually only increased by 48F. This decreases my theoretical future power output potential by about 2%.

I also forgot to mention that with 550/1650cc injector setup at 40lbs of base fuel, I ran a max duty cycle of 82% with the average between 5500 and 7500 at 74%.

Can you tell I like to datalog!!

Carlos,

I missed the boost levels. My eyes are bad! Where are taking vacuum from?

In a run from 40-140mph I see a 20C increase in intake temps...starting at 22C going to 42C. Running the Apex'i FMIC, soon to be Greddy 3-row. I think the GT40r does a good job of compressing the air!

With my 860-1680cc setup I see 84% duty up top (at 11.2 AFR...38psi base fuel pressure), with a an average about like yours from the 4 datalogs I looked at.

Amen to logging, I have a new Innovate LM-1 and Aux box setup that will allow logging of FP, EGT, and IAT. Got to have data when you go testing!

Sent a pm, too.

Tony