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Hey Stu, are you taking payments already? I can send whenever your ready. Also, are there anymore revisions in the works for the turbos or are the gt28s the final option?
 

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Stock Twins King
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Yes I had 20 1 week ago and now down to 10. I eventually will make more but I want to see SOME results from people. I have one with your name on it lol....I REALLY tried to get the cost down but I also didn't want to lose a ton. I have so much invested it is crazy. So I am at $1400 Dlvd and can send anytime.

The new V4 are on there way to BNR. Maybe within a few weeks but the beta set isn't in yet and my turbos are there waiting to install these V4s. Not sure but there can be issues with them which I will know any day.

These also come at a higher cost of +$250. So the set will cost $2250 instead + $500 Install kit. Add $1400 in the manifold it is getting steep at $4,150. But this stealth setup isn't for everyone. Visually no one will even know you are packing up to 700whp. In sequential as well. Real sleeper, specially for California laws
 

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pm sent.
i checked BNRs site and they dont show much on there unless i'm missing something. regardless, if you say they're good then i'm fine with that.
 

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pm sent.
i checked BNRs site and they dont show much on there unless i'm missing something. regardless, if you say they're good then i'm fine with that.
I would say this is one of the biggest blunders with these gt28 twins. lack of centralized information for all the available products Stu has made to date. I wish BNR or Stu would have put a dedicated info in each of their own website and make it clear for those to access.

But just for those that are new, this is what I have gathered so far.

GT28r hybrid twins V2, V3, V4 based on different compressor wheel designs/flow. V1 didnt have volutes ported for sure while V2 is either V1 with ported volutes or V3 without ported volutes. Actuator choices are standard 11-20 PSI and heavy duty 20-30+PSI

Enlarged EBV pipe to help with quicker transition in sequential mode. Ideally needing iron collectors and gaskets port matched to the enlarged pipe for best results.

Custom cast exhaust manifold for both USDM and JDM motors.

I am in the process of piecing my Stu set up with the exhaust manifold, enlarged EBV pipe, and V1 rebuild with ported volutes through BNR. Exciting yet excruciatingly painful waiting for it all to come back.

Tsung
 

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The Great Beast 666
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I tried to yank these from SFS because they were asking too much They were $3200 and I am $2500... But then I am not a business and I am not into this for profit.
Yeah,it was $3200, BNR lists the JDM version for $1750, which I am assumung that they are also using the same price for the USDM ones.

$4500 is not bad considering what you get and the stealthiness of it all.
 

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I agree not enough 2JZ info on BNR website. I called him last year to get info on these turbos and why USDM was so much more expensive than JDM and he told me to standby for news on a new GTX cartridge for this setup. I am not sure if this is the "V4" Stu just mentioned. $4k+ is just the start. Seems we will still need fueling and stand alone ECU and everything else needed for a single to make it all work. Someone hurry up and install these manifolds!!!
 

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I've been following this long enough to know that v1 and v2 are not really worth it at this point. V3 will get you the most for your money but I also heard that the V4 would be a GTX upgrade but wasn't sure about that. Only thing I don't remember is the usdm vs JDM thing. I could have swore one was a better upgrade than the other but can't remember. But if it's true then you can pick the best one since you can run either setup on this manifold.
 

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Someone may speak up on the exact JDM specs, but from my research, the Aussies have been very popular and successful with JDM hybrids. Check out Munro Racing. There may be significant savings for us by locating a junk set of JDMs (CHEAP!!!) and sending them BNR for STU GTX re-milling to be used with these new manifolds.
 

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Someone may speak up on the exact JDM specs, but from my research, the Aussies have been very popular and successful with JDM hybrids. Check out Munro Racing. There may be significant savings for us by locating a junk set of JDMs (CHEAP!!!) and sending them BNR for STU GTX re-milling to be used with these new manifolds.
That's what I was thinking but remember, they don't have a USDM option over there like we do here
 

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Stock Twins King
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I am seeing some good constructive criticisms here RE: BNR. I have known for a long time that he doesn't have anything about USDM GT28s on his site. I think this will change as the reason was, JDM are 100% P&P whereas USDM require an installation kit. Bryan isn't interested on doing "kits" as all he does are turbos. I am working with Bryan to keep some kits in stock so he can then have a write-up on GT28's It dosent help that I am not a business where he can provide a "link" for the installation kit that I make and provide. TBH I wouldn't mind getting out of selling these as I really only made $50/set. Goal was to get these out there as at $3200 they were no selling.

The JDM upgrades are different builds using Mitsubishi 16G CHRAs, He sells them for $1,750 + cores. I have a set of these on my Supra now (removing them this week). I made 620whp at 28psi, manifold, and Artec Hi-Flow collector. I do hear that Munro are a pretty good alternate. The obvious is they are in AU vs BNR in USA. Plus I really do not know what a Munro costs. Also FYI BNR is sticking to using 16G and no plans to change to a GTX style set up

As a final note, these new GTX wheels come at a +$250 extra cost. More info to follow once I know more
 

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Are most of you that are doing going to be running Aftermarket ECU's or are you running Stock ECU with piggybacks? I feel like I am in the minority here wanting to run the stock ECU with no piggybacks on these turbos, which severly limits their gains.
 

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Stock Twins King
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Ishii's shop has done a couple of GT28 installs to stock supra's. Only BPU was a boost controller and catback exhaust. They seem to avg around 430whp on pump gas at 16psi. Without getting larger injectors (requires a piggy back) you are for sure limited to about 480whp max. The 550cc injectors are good to about 475ish Whp at 80%IDC. OEM FP is good to maybe 500whp. So you can still get great results but you are leaving a lot of power on the table. But it for sure gives you room for future mods. TBH I really cannot venture to say the gains on the manifold being so close to OEM configuration. Still same issues, even if you do gain HP your still limited to same overall level of power.
 

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Ishii's shop has done a couple of GT28 installs to stock supra's. Only BPU was a boost controller and catback exhaust. They seem to avg around 430whp on pump gas at 16psi. Without getting larger injectors (requires a piggy back) you are for sure limited to about 480whp max. The 550cc injectors are good to about 475ish Whp at 80%IDC. OEM FP is good to maybe 500whp. So you can still get great results but you are leaving a lot of power on the table. But it for sure gives you room for future mods. TBH I really cannot venture to say the gains on the manifold being so close to OEM configuration. Still same issues, even if you do gain HP your still limited to same overall level of power.
So for someone like me it probably doesnt make sense to get your new manifold unless I am willing to go aftermarket ECU. It sounds like my best bet would be to just get the turbos only and use the stock manifold and possibly port that. I will shoot you an email too about it.
 

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Moderator, l337 M0d3r4t0r
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So my 2 cents here... The reason I think BNR likes the 16G wheels is because of the simple fact that they seem to like high-pressure ratios. The problem with the stock twin upgrades (not hybrid) is there is limited flow in the housings. Stuffing a bigger wheel to flow more really doesn't help... It's like having a firehose with a garden hose nozzle. It is severely limited by the housings. JDM"s have bigger housing therefor will make more than just the USDM upgraded twins. Hybrids are even bigger...

That being said, I think the reason why BNR likes 16G wheels is not for overall flow volume but pressure ratios it can still flow at. Many of the EVO guys run like 40 PSI and the reason they can do that is the turbo wheels can still make power at that pressure ratio where the GT28R's fall on their face. Stuffing bigger wheels does not = more power in this case. You need more pressure to overcome the resistance of the smaller pipes and other restrictions.

My twins are not actually BNR twins, they where drift motion twins that I bought for next to nothing. They were in excellent shape, but I ended deciding after taking off the twins and the amount of work that it took that I wasn't going to gamble and do the job twice. So I had Albert Meades rebuild them in AZ with billet compressor wheels. I have all the supporting mods, 4" ic, 1300 CC FID injectors, and I'm thinking of going standalone (on the fence) using an emanage with a modified ECU. The reason I love the stock ECU is the ability to run max timing all the time and pull back if knock is found. Most if not all EMS systems never push that limit because the knock sensors and knock response are just not near the OEM level of tuning.

Stu, I replied to the PM, didn't know the manifolds where ready... I'm ready to send the money.
 

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I have been studying up on the gt28r sequential transition points of multiple dyno graphs and even my own with just BPU vs stock boost level. I realize that the stock ecu triggers the transition point earlier at say 3.6-3.75k rpm when running the gt28R or even just my own stock twins at bpu boost levels of 16-18 psi. In my dyno below, it was run with EBV spring pressure at 13 psi, and blue line is 11 psi stock boost with 0 wg duty cycle and red is 16 psi taper to 13 psi.

252880


I think for all of us looking to run / already running the gt28 with stock ecu, non-e85, we need to investigate on how to activate the transition point at the originally designed 4k RPM or even 4.25k rpm to make the transition as seamless as stock. Now, munro racing page had mentioned tapping into the IACV vsv or IACV pressure hose to delay the activation. I personally dont like the methods being done in the post, but the concept of intercepting the IACV signal and activating based on when I choose is a much more promising idea. I already have ettc switch wired where I have 2 switches one for the egcv and one for the IACV vsv signal. I will look into manipulating the iacv vsv switch on the fly and see how the car performs. If it works well, then I would have an aux output based on RPM, assuming the vsv takes 12V, and voila, poor man's transition point mod.


I am still brainstorming this and unable to test the theory due to my second turbo being blown... but I am looking forward to it when I get the gt28r back and installed. Hopefully this could help someone else trouble shoot their hybrid twins if still in stock ecu/piggyback

Edit: further notes on my dyno graph. Red graph, I lifted throttle in the beginning of the dyno run and caused the initial dip. I added the green one To show what a normal run should have been as it was one run before my fuel tuning. The blue stock wg setting may look slightly off because I already had my ebv spring mod done so the wg pressure was lower than the ebv actuator.
 
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Stock Twins King
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My notes state that the OEM configuration is EGCV opens at 3750 and IACV 3800. Ful transition maybe 4200rpms. You do have to keep in mind that the higher you go pre-transition boost wise the greater the dip. That is because it takes more energy to get the #2 up to the same speed from boost pressure from #1. The lower you go the least dip. If you look at a stock twin dyno the dip is like 1psi at most. (Below)

The #2 is almost dead still so it has to get to the same speed as the #1 to catch up so it robs all of the boost pressures for a few hundred RPMS hence the dip/
252898


Your Green graph is the best of them the others look like a bad VSV going on. Not suppose to do that wavy shit.
 

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You are not alone. I'm also looking to keep the stock ECU with hybrids and maybe increase the fuel pump voltage. Now, I'm leaning towards the JDM hybrids. Good info here! Keep it coming.
Are most of you that are doing going to be running Aftermarket ECU's or are you running Stock ECU with piggybacks? I feel like I am in the minority here wanting to run the stock ECU with no piggybacks on these turbos, which severly limits their gains.
 

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I agree that higher the pre transition boost the less exhaust pressure is there to spool the second turbo, especially if transition still happens at the 3.75k rpm.


Looking at beezupra’s gt28 v3 smic dyno in ttc vs sequential dyno above, the initial power curve looks great but the transition at 3.75k rpm caused the system to drop to the ttc trajectory. If we can push that transition point to 4.25k rpm, then there is enough exhaust volume at that rpm to move both turbos. To me, the dyno shows the car starts in sequential mode, and then runs in ttc early.

I updated my previous post to explain the odd curves in the dyno
 

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Long time member on here - I finally picked up a 6spd turbo supra from 2jzmotorsports in utah early this year.

It's completely stock except an HKS ti exhaust and megan racing downpipe 2jzmotorsports installed before I took delivery.

Strongly interested in your long running STU turbo upgrade. I'm located here in Washington State - plan on having Ishii Motorsports do the deed if I move forward.

Powerwise - I would be happy anywhere from 450whp - 500whp. What's most important to me is keeping the stock like driveability - hence I'm not interested in large singles or extensive mods.

Would the STU turbo v4 be the best fit for what I'm looking for? I think so - but wanting to confirm.

I don't have a FMIC - still on stock SMIC - which I think should be adequate for what I want in my power goals? It sounds like above 500 whp would require FMIC, injectors, ECU mods.
 
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