Testrun

billyboy

You could direct questions to GCG turbos here if interested.....shouldn't be any google translate involved! They've been doing variations on the twins for 20 odd years.

Slings and arrows of currency and inflation haven't done any favours, they originally used to sell their reworked stockers for around 2.5kAu from memory, you can see Ric's price around 10 years back https://www.fdrx7.com/forum/showthre...gh-Flow-Twins& and they're north of 7k in the local peso now! Gets you a fair way along on a single conversion.

Jatt

iTrader: (2)

I read that entire thread, was such a mess of a thread. The Doctor clearly being shady and overselling/exaggerating them without providing any sort of numbers or legit data.

Are these the same ones? I remember on that thread people stated Ari had them, really look forward to seeing what you output with 16 psi on these twins. Nobody has provided good data on them after all this time, i think.

Testrun

They are not the same. The Dr has a larger compressor on them. I am sure they are awesome, but with the exhaust flow restriction I don't think they would really do much better than these. It is sad that all that went down the way it did lol. I would still like to see some real world results. Now, from what I understand as stated before these will no longer be made, but another company will pick up the moldings and they will be the same turbos under different a name​​​​​​​.​​​​​​​​​​​​​​

Testrun

The 3kai are suppose to be superior to these. ​​​​​​​I still think it is very odd there isn't more info about these with how much support there still is for the FD.

fc3s-ty

iTrader: (11)

Yeah I have been a forum lurker for a long time, and these have been on my radar.

the GCG links I posted above I think clear it up-

the HT12-3b should be the equivalent to the GCG #HT12-3CR, which is simply the 99+ Spec 280PS, Bolted and abrade-able compressor housing. N3G1.

GCG lists the 3KAI in their “high flow turbine” tab. Akin to an in-house, BNR-esque, Hitachi. It’s the top of the line OE type turbo.

I agree that we need some numbers on these. Thanks for the responses Club

mikejokich

iTrader: (1)

I found out about these 3KAI's about 5-6 years ago or so. I bought mine from Ari back then during a major rebuild of my '94 FD. (I used them during a 5-6 month shake down period (tuning, etc.) but never boosted over 12-14 pounds. I had a major engine failure during tuning and unfortunately the car has been down for the last 2.5 years with a brand new race balanced engine under my car and lift for the last 2 years). I talked to Ari and several others at that time, and here is my understanding of how these came about. The engineers at Hitachi had been developing a newer turbo to supersede the "99 spec version that would take more abuse due to 360 degree seals and thicker shaft, flow more on the intake side, and be an otherwise direct replacement. If Mazda hadn't killed the FD, these likely would have been in the next version following the '99 spec cars. Many years later, since the demand for replacement turbos was still strong, the Hitachi engineers convinced the company to allow them to make the newer version as an option for FD owners. These are therefore, as far as I know, not modified after the fact, but are produced like this straight out of the factory. All the charts and graphs I provided were found by me through research on the internet and I shared them with everyone. I even had the true Japanese versions translated by my son's Japanese friend from Tokyo. I truly believe that if anyone is sticking with the twin sequential setup, I would never purchase the older stock versions except if money is very very tight. These will last longer and boost better. I would go with these vs. the newer BNR's, period.
Mike

fc3s-ty

iTrader: (11)

Awesome info Mike, great summary. That was my understanding and hunch, but still wondered about various part numbers, sources etc. Look like they are the best option for oe twins

Jatt

iTrader: (2)

If I read that correctly the 3KAI are the ones Ari sells (?) and your current car is out of commission awaiting a rebuild? Really really hope you get it rebuilt and running again and we can get some cool data.

I'd love to stay twins in the long, long term (once my 99 spec die) if it was a feasible option over going 8374.

mikejokich

iTrader: (1)

Ari, from RX7.com out of Texas, still lists the 3KAI's or SP's and the Efini "99 specs for sale. My rebuild was extensive (3 years), with 7 major new systems and/or upgrades, added to the car. To many things to list quickly. I did install custom actuators on the new turbos with adjustable spring rates. See some of my posts from several years ago. Unfortunately, the main keg was from an older overhaul from around 10 years ago and didn't hold up well to some tuning problems. I have been working on a major three-room Lord of the Rings home theater project that has taken all of my spare time over the last 2.5 years, hence the reason my new engine is still crated on the garage floor. The theater is 95% complete and should be completed by late spring. Then, its back to the FD. I just have to install the new engine and my rebuilt trans. Everything else is still complete and I hope to be back on the road by early summer after swapping the parts on the engine.
Mike

tqm397

iTrader: (2)

Looks like the high output 3KAI turbos are no longer listed on Ari’s site: RX7.COM | 93-95 Rx7 Turbo

This must’ve changed within the last day or so because I checked earlier this week and they were still listed.

Does this mean that the only source for the HT12-3KAI would be GCG Turbos Australia? GCG Japan’s site seemed to indicate that they only sell through dealers and not direct.

billyboy

With the other amigo here not able to get the cores for his version by the first half of last year, probably wouldn't bode well for GCG being an exception.

Jatt

iTrader: (2)

If you ever end up selling the 3KAI's for a reasonable price, you know who to PM.

TG888

iTrader: (15)

TCP Magic sells the 3KAI.

https://www.tcpmagicusa.com/product-page/tcp-magic-twin-turbo-set

https://www.gcgturbo.co.jp/products00.php?menu=products&display_id=search&id= 685&search_w=3kai

Hitachi and GCG jointly developed.
Genuine 280 horsepower turbine base.
Uses a machined aluminum billet compressor wheel.
The capacity of the compressor wheel is increased by 10% compared to the normal.
Low friction seal type.
Adjustable actuator.
Actuator port processing.
Changed the compressor inlet from genuine plastic to machined aluminum.
Of course, all are new parts, so there is no need for genuine trade-in like rebuilt products. ...

Jatt

iTrader: (2)

If these were in the high 2,000 USD range, I think these would be a pretty viable option as opposed to going BNR or single, even if they are not "miracle" twins as some people had sold them as. Pretty cool and worth considering...

Wish we had more data on it, long term would be cool considering for sure

DaleClark

iTrader: (55)

So GCG has the compressor map on their website, it looks like stock on left, 3KAI on right.

Any compressor map reading wizards out there? This should give a lot of info as to spool, power, etc.

Dale

tqm397

iTrader: (2)

Thanks TG888. $3400 is definitely, by far, the lowest price I've seen for the HT12-3KAI. That's actually just about the same price that you can buy '99 Spec N3G1 turbos from Mazda Motorsports, which would make the 3KAI a great deal.

REnaissance_Sle7in

iTrader: (8)

On this subject, I've always had the belief that the turbos sold by Revolution were also just the same GCG 3KAI turbos. Can anyone confirm this?

djseven

iTrader: (56)

Any link to where someone is trying to go 9s on these twins? I had yet to see anyone go 11s with these mythical turbos Marcus talks about.

Carlos Iglesias

iTrader: (6)

...more like a compressor reading hack, but here goes:
At a quasi-arbitrary Pressure Ration of 2 bar (14.5psi gauge pressure) the individual turbos EACH make 22.5 and 25.1 lbs/min.
Double that and you obviously get 45 and 50 lbs/min.
Multiply by 7.7 for rotaries (SWAG... Scientific Wild *** Guess) gives you an absolute potential 346 and 385 FWHP @ 14.5 lbs respectively.

Looks like there may be a little (5%) more powers available at lower boost levels if the engine can flow it.

Of note, at 14.5 PSI the turbos are spinning faster (140K PRM) than politician caught in a motel with a underaged 'constituent'. Wouldn't expect much of a future left at that point.... if you knwo what i mean!

Testrun

I Never said thanks for the reading the charts. I am not sure if there will be a dyno available at the DGRR this year, bit if there is I will put the car on if anyone wants to see. They whare definitely ready for 14-15psi, I could try to have them ready for a 16psi run. ​​​​​​​There are two 2 members on here (forgot the names), but one runs a time attack with these at 16psi and another that runs a track and they both run at 16psi. Both have said no issues with the reliability.