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Racing is Life.
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Discussion Starter #1 (Edited)
Hey guys and gals,

I don't have any pictures I can post here, unless you come to my Owners Group and see them there.

The basic setup:
✔ HKS Twin GT2835s setup, GT2835 turbos removed. The entire manifold system and downpipes are DEI Titanium wrapped for high efficiency and to keep the oil feeds and coolant lines and wastegate hoses safe. Everything even the wastegate hoses are AN and heat sleeved with DEI aluminum heat sleeves.
✔ New Garrett GTX2971R supercore turbos into the GT2835 turbine housings
✔ All AN coolant lines along the OEM routing with the water lines routed per the Garrett white paper. The water lines connect to the AN fittings on the water neck and water pump with weld on 6AN bungs. All the lines are stainless 6AN braided with DEI aluminum heat sleeves.
✔ Greddy 3 Row on ALL custom piping from PHR on throttle side and done by me on turbo side
✔ HKS Super Dragger on custom 3.7" piping all the way to the merge pipes which are 2.5" downpipes
✔ AEM Infinity 506, tuned and setup by yours truly
✔ One single 285/525/Hellcat pump (for now)
✔ Stock feed modified to accept AN hose at the stock filter and return (again, for now)
✔ PHR rail
✔ Bosch 210lb 2000cc injectors
✔ Complete interior Rattle Trap sound proofing from window sills down, firewall down, trunk deck down, added 20lbs, HP can resolve 20lbs
✔ SSR GT3 19x9 19x10.5 and Toyo Proxes Summer 1 305 rears, Toyo 255 fronts
✔ Peter Kopoulos SRT8 BBK Conversion front and rear
✔ BTI can gauge
✔ RPS Triple Carbon clutch

I'm sure I've missed a ton. Ask away lol

I have a Radium fuel pump hanger and twin Hellcat pumps I plan to drop in and run a single new -8 feed to a Deutschwerks giant filter. The filter flows 250gph. I also have all JiffyTite fittings ready to go for this as well which will allow for popping the fuel filter out with the snap of a finger and it dry breaks, so no fuel leaks while cleaning out the filter. The rail will get a dry break quick disconnect as well to make pulling the engine easier when I do the 3.5L VVTi build and swap that in.

Here's a short video I made.

 

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Jason,

I am quite excited about this conversion and sent you a more detailed PM about it. Can't wait to see what she does and how she performs once you get everything all buttoned up. Those drop-in Garretts make a very persuasive case for your consideration, and ultimate adoption, of this approach. Best of luck!


Ken.
 

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Racing is Life.
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Discussion Starter #3
Thank you Ken! I promised my wife I'd not go to the garage for a few days. I basically went full obsessive to get this part finished. I had a cracked AC hard-line and so I needed to do that as well before I could out the turbos in. As you know the AC hard-line simply cannot come out with the turbos in the way.

I can tell you just getting the car up onto ramps to bleed the cooling system the turbos are coming alive way earlier and more than I anticipated based off of the GT2835 when they were in the same state. Could just be noise but the sound lent me to believe that they were coming in at only 1700rpm. Granted - there isn't any intercooler piping on the outlets yet. I totally get that's bad lol but just moving it up onto the ramps made them come on at a level I haven't seen before on any of my single cars if a pipe ever blew and I needed to limp to a place to secure the piping. Basically I am in the camp that these will not only make more power but have better response. Not only that but with the steel cage bearing cartridges - I'm really glad I went this direction.

I thumbed through the Garrett site for a bit. Seems like the closest thing I can find to match up is the Gen II GTX3076R. Now this wouldn't retain your exhaust housings like my setup has, but the end result looks like it could be worth the minor changes necessary if the rebuild situation ever crosses your path. Hopefully that doesn't happen but if it should: check out that compressor map!

Turbo by Garrett GTX3076R Gen II

Basically it looks like you could run a smaller turbine (better spool), a smaller compressor overall that is billet that flows 30% more than a cast wheel and spool that much sooner all while making more torque and overall power. It looks like the map should be well within the breathing range of our motor.

If you wanted to go smaller along my lines all you'd need to do is fine a set of HKS housings with the AR you want and go from there. Could be a search but I actually know someone who has a set of GT2835s laying around needing rebuild. So just say the word should you ever decide to go that route. The GTX2971R with 73 AR housings should spool well and make some great smooth power. That's what I'm hoping for at least!
 

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Racing is Life.
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Discussion Starter #5
I would keep it. It was all worth it in the end. The car runs and boosts and drives. I discovered that the PO of this kit had 18-22si springs installed, so it boosts way too high for the stock fuel system. I’m going to pull the motor to go over everything on the engine and install the fuel system, oil cooler, 14-18psi springs and reseal the pan and entire engine, as well as GSC S1 cams and conical springs and GSC Viton valve seals. I’ve got a lot to do but it’s almost done.

 

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handy with the steel
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I have started tearing into the turbos on the used 2835 kit I bought and it looks like I'm going to have to go this route or similar. One of the blades has contacted the compressor housing and it's bent. I'm guessing this isn't good for the turbo ¯\_(ツ)_/¯

Obviously the biggest consideration with going to a GTX supercore is fitment with the HKS turbine housing. If I'm understand correctly, all of the Garrett GTX29-series will have one of two turbine wheels:

Inducer: 56.5mm
Exducer: 51.8mm
Wheel Trim: 84

or

Inducer: 56.5mm
Exducer: 53.6mm
Wheel Trim: 90

Do know which Turbine wheel your supercores came with? I wonder if they both would work with the HKS housings?
 

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I have started tearing into the turbos on the used 2835 kit I bought and it looks like I'm going to have to go this route or similar. One of the blades has contacted the compressor housing and it's bent. I'm guessing this isn't good for the turbo ¯\_(ツ)_/¯

Obviously the biggest consideration with going to a GTX supercore is fitment with the HKS turbine housing. If I'm understand correctly, all of the Garrett GTX29-series will have one of two turbine wheels:

Inducer: 56.5mm
Exducer: 51.8mm
Wheel Trim: 84

or

Inducer: 56.5mm
Exducer: 53.6mm
Wheel Trim: 90

Do know which Turbine wheel your supercores came with? I wonder if they both would work with the HKS housings?
based on this...https://www.suprastore.com/hksgt2835turbo.html

it looks like a Turbine wheel of 56.8 major / 51.8 exducer
 

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Racing is Life.
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Discussion Starter #8
Either fits. If you look at the Garrett site "these are available as a direct drop in for GT28 series turbochargers". I verified my trim as the same as the 2835 but ultimately you can go with either.

Suggestion: go GTX2967R. The 71R is great and all but the improvement in performance vs the 67R isn't worth whatever lag I have. Granted.... Once it comes on it feels great. So I'll be able to give a better idea of it's performance once the fuel system is installed.
 

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Discussion Starter #9
Oh. Plus getting the 4" intakes to clear is tricky. It definitely fits. Barely lol
 

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Thank you Ken! I promised my wife I'd not go to the garage for a few days. I basically went full obsessive to get this part finished. I had a cracked AC hard-line and so I needed to do that as well before I could out the turbos in. As you know the AC hard-line simply cannot come out with the turbos in the way.

I can tell you just getting the car up onto ramps to bleed the cooling system the turbos are coming alive way earlier and more than I anticipated based off of the GT2835 when they were in the same state. Could just be noise but the sound lent me to believe that they were coming in at only 1700rpm. Granted - there isn't any intercooler piping on the outlets yet. I totally get that's bad lol but just moving it up onto the ramps made them come on at a level I haven't seen before on any of my single cars if a pipe ever blew and I needed to limp to a place to secure the piping. Basically I am in the camp that these will not only make more power but have better response. Not only that but with the steel cage bearing cartridges - I'm really glad I went this direction.

I thumbed through the Garrett site for a bit. Seems like the closest thing I can find to match up is the Gen II GTX3076R. Now this wouldn't retain your exhaust housings like my setup has, but the end result looks like it could be worth the minor changes necessary if the rebuild situation ever crosses your path. Hopefully that doesn't happen but if it should: check out that compressor map!

Turbo by Garrett GTX3076R Gen II

Basically it looks like you could run a smaller turbine (better spool), a smaller compressor overall that is billet that flows 30% more than a cast wheel and spool that much sooner all while making more torque and overall power. It looks like the map should be well within the breathing range of our motor.

If you wanted to go smaller along my lines all you'd need to do is fine a set of HKS housings with the AR you want and go from there. Could be a search but I actually know someone who has a set of GT2835s laying around needing rebuild. So just say the word should you ever decide to go that route. The GTX2971R with 73 AR housings should spool well and make some great smooth power. That's what I'm hoping for at least!
To fit the GTX3076R, couldn't the HKS exhaust housing be machined to fit the new core?
Inducer 57 --> 60
Exducer 52 --> 55

pardon my ignorance if this can't be done.
 

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handy with the steel
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377 Posts
Hmm or maybe I go the other way: 2976r...640hp each

Decisions decisions...
 

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handy with the steel
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377 Posts
Thank you Ken! I promised my wife I'd not go to the garage for a few days. I basically went full obsessive to get this part finished. I had a cracked AC hard-line and so I needed to do that as well before I could out the turbos in. As you know the AC hard-line simply cannot come out with the turbos in the way.

I can tell you just getting the car up onto ramps to bleed the cooling system the turbos are coming alive way earlier and more than I anticipated based off of the GT2835 when they were in the same state. Could just be noise but the sound lent me to believe that they were coming in at only 1700rpm. Granted - there isn't any intercooler piping on the outlets yet. I totally get that's bad lol but just moving it up onto the ramps made them come on at a level I haven't seen before on any of my single cars if a pipe ever blew and I needed to limp to a place to secure the piping. Basically I am in the camp that these will not only make more power but have better response. Not only that but with the steel cage bearing cartridges - I'm really glad I went this direction.

I thumbed through the Garrett site for a bit. Seems like the closest thing I can find to match up is the Gen II GTX3076R. Now this wouldn't retain your exhaust housings like my setup has, but the end result looks like it could be worth the minor changes necessary if the rebuild situation ever crosses your path. Hopefully that doesn't happen but if it should: check out that compressor map!

Turbo by Garrett GTX3076R Gen II

Basically it looks like you could run a smaller turbine (better spool), a smaller compressor overall that is billet that flows 30% more than a cast wheel and spool that much sooner all while making more torque and overall power. It looks like the map should be well within the breathing range of our motor.

If you wanted to go smaller along my lines all you'd need to do is fine a set of HKS housings with the AR you want and go from there. Could be a search but I actually know someone who has a set of GT2835s laying around needing rebuild. So just say the word should you ever decide to go that route. The GTX2971R with 73 AR housings should spool well and make some great smooth power. That's what I'm hoping for at least!
To fit the GTX3076R, couldn't the HKS exhaust housing be machined to fit the new core?
Inducer 57 --> 60
Exducer 52 --> 55

pardon my ignorance if this can't be done.
I’m not super knowledgeable on the subject, but I don’t think your average machinist would be able to do this. It’s not just a matter of using a lathe to widen the inducer and exducer clearance. The turbine blades are curved, but the radius is not constant. It may be possible, but I’d definitely be looking for a machinist or company that specializes in working with turbos.

That said it would probably be easier to weld new flanges on the manifolds and downpipes to fit different turbine housings.

Just a WAG
 

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Racing is Life.
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Discussion Starter #13

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Racing is Life.
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Discussion Starter #14
I’m not super knowledgeable on the subject, but I don’t think your average machinist would be able to do this. It’s not just a matter of using a lathe to widen the inducer and exducer clearance. The turbine blades are curved, but the radius is not constant. It may be possible, but I’d definitely be looking for a machinist or company that specializes in working with turbos.

That said it would probably be easier to weld new flanges on the manifolds and downpipes to fit different turbine housings.

Just a WAG
This is exactly. It. I'd be hesitant to begin with. A shop like Boost Lab can do it but I'd be super concerned about it working correctly.
 

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handy with the steel
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Racing is Life.
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Discussion Starter #16 (Edited)
I wanted to give an update on my car.

244362


As it turns out: I had a wastegate line on backwards. I color coded all of my lines and during installation had to make some changes to get it all to fit and forgot to note the hose colors were changed. I didn't discover this until scratching my head endlessly after doing the fuel system and discovering it was boosting well past 27psi as well. Bit of an oversight.

I have 16psi springs and the car is really nicely to drive at that level. The response I've gotten used to and I admit it's now addictive. It just keeps building and building more and more power and ramps up so progressively.

I have the Infinity setup to manage traction control and boost through a 12 position switch. I'm enjoying tweaking and learning what is ideal for each setting.
Positions are:
Setting: TC level, boost
0: TC off, 16psi
1: 5mph, 16psi
2: 5mph, 24psi
3: 5mph, 27.5psi
4: 10mph, 16psi
5: 10mph, 24psi
6: 10mph, 27.5psi
7: 15mph, 16psi
8: 15mph, 24psi
9: 15mph, 27.5psi
10: 25mph, 27.5psi
11: TC off, 27.5psi

244361

I finally found time to Dyno the car to optimize timing etc. It made 705whp/625ftlb at 27.5psi. I elected to stop there until I added the additional fuel pumps and head studs and cams. My fuel pressure peaks around 60psi and slowly drops to 50psi at 27.5psi of boost. This is on a single stock feed line adapted to 6AN and a Walbro 267 450LPH and Bosch 210lb injectors at 0.80 lambda.

Dyno Run - Please consider subscribing!

244360

I'm really pleased with is how wide the rainbow of horsepower is. I'm a little annoyed at the torque band because it dipped off due to a setting I had left from street tuning. Basically if intake temp went over 130°F it'll pull 2° and 140°F it'll pull 4° of timing. And that reflects on the Dyno plot. After speaking to Bryan at PHR and a couple other tuners I am being way too conservative with the timing reduction. So I'll move the temperature threshold up quite a bit, to around 150°F to pull 2° up to 180°F and pull 4°.
244363


I talked with Jay at Real Street for several hours. After a lot of discussion I've elected to do a 3.5L VVTi 9.0:1 built engine. This should really get the system online much earlier and give me what I am hoping for in terms of low end grunt and boost response. Between the 3.5L and the VVTi benefits I really hope I can get the chart to shift "left" on the Dyno several hundred, if not a thousand RPM. Nothing is more beautiful than a nice responding decent power twin setup.

I hope you're all having an awesome day. Me? I'm finishing up hurricane prep and needed to take a minute to get my mind off of it.
 

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handy with the steel
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Stay safe in that Hurricane!
 

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Sweet! I was wondering the other day if you ever got around to putting these turbos on the dyno!
 
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Wouldnt a single 6870 have a better curve than this Jason?
Sick setup but I think you can drop some weight and gain more power all around, especially would what Turblown is doing with their integrated QSV in the turbine housing you could grab an 8474 and blow this away.
 

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Racing is Life.
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Discussion Starter #20
Wouldnt a single 6870 have a better curve than this Jason?
Sick setup but I think you can drop some weight and gain more power all around, especially would what Turblown is doing with their integrated QSV in the turbine housing you could grab an 8474 and blow this away.
If the question is "Would it be simpler and more cost effective to have the same if not better power band?" Then Yes is the simple answer. All my life from 10 years old and onward I wanted an HKS Twins setup. Now I've one upped my dream. With a stroker and VVTi it'll respond just as well as most good responding single setups, and have a power band that IMO is more fun to drive. There's a part of me that doesn't want to change a single thing. I'm going to go autocross it today and I'm loving it. I've seen some video of VVTi setups helping spin fairly big turbos right up at pretty low RPM. So this is happening. After talking to Jay and him describing the stroker responsiveness I've pretty much settled on it. It should be a really nice all around package, maybe it'll make 900whp, maybe it won't. But its power delivery as is makes anyone that rides with me scream like a girl as the freight train builds power.

Also keep in mind that I elected to top at 625ftlb. I still only have a single Walbro 450 on a stock feed line lol, stock head studs, stock cams.....

Let's not forget when I go to a car event and pop the hood EVERYONE stares and gaulks, including me. :)
 
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