superbike81

Ok, I'm looking at this set of turbos to buy as a replacement/upgrade for my stock turbos, but the turbo has been overhauled with custom parts, so I'm a bit confused.

They started life as a pair of HKS 2510's. My Japanese is fine for speaking, but reading is pretty busted, so I'm basing this off of the Babelfish translator.

- HKS 2510 rebuilt for "super response" (faster spoolup I'm guessing)
- Some kind of "partition" in the exhaust housing to improve flow
- Compressor blade is from GT-SS turbo 60 trim (I think)
- 0.48 exhaust housing 0.60 compressor housing

Here is the original description in Japanese:

HKSのGT2510ツインタービンをO/H時にハウジングを組換え、R34純正ボールベアリングタービンのような超レスポンス仕様に。 EXハウジングバイパスポートと排気口に隔壁を設けたことで排気の流れを整流し、排気効率を向上させた。R 34純正タービン以上の高回転の伸びとブースト圧の安定を狙い、コンプレッサーブレードをSR20 用GT-SSタービンの羽へ変更。」という商品を友人の依頼でオークションにて代理落札しましたが、事情により車両 を手放したため装着せずに未使用で余ってしまいました

(Anyone here read Japanese? My wife is Japanese but she doesn't know anything about cars, so she doesn't understand what it says).


And the pictures:








Does anyone have any idea roughly how much horsepower each of these turbos is capable of? Should I expect more or less than an original set of HKS 2510's (which is ~600hp)? I'm guessing less due to the smaller exhaust housing, but quicker spoolup? I'm no turbo expert, still learning.

I'd appreciate any help.

Thanks!

busa4

they should be good for 200-250hp of airflow each. depending on your engine size they should spool up quickly. they look like t25's with the small t2 turbo inlet flange.

superbike81

Well hopefully more near the 250 range. My engine is a 2.6 (RB26DETT), that's mostly what I'm after is spool time, but the stock RB26 turbos have a ceramic wheel and don't like anything over about 15psi (420hp or so) before it starts getting dangerous. I would like to be able to make 400whp with these, I guess we'll see.

Thanks for the info!

I am going to get them, and once I do I'll post full serial numbers and everything so hopefully we can get a better idea.

busa4

your obviously looking for big hp number so i would scrap the twin turbo setup and go with one bigger more efficient turbo. yes, you will sacrifice low end but your top end will be where you want it. unless you can afford a variable vane turbo you will have to sacrifice one or the other. low end torque with less hp you are going to want smaller turbo's. high lag with big hp numbers your going to want one large turbo.

busa4

i would go with one gt35 turbo for big hp numbers or two t28's. these are t3 flanged turbo's where as those pictured above are t2 flanged turbo's.

superbike81

But that's the thing, I don't do much drag racing or highway running. I'm a touge (canyon racing) and gymkhana (similar to Autocross) type of guy. Which is why I'm going for smaller twins, ~450whp is not big numbers for the Skyline, that's pretty tame actually. So I'm doing my best to get some extra power out of it while keeping spoolup time to a minimum.


I have now verified it's a 0.80 A/R on the compressor housing, does this help any to come up with a more accurate number?

busa4

i see. theres no point in high rpm power then. those two hks25's should be more than enough to support 500hp with a nice low spool time. id figure they will spool at ~2000rpm

superbike81

That's perfect, ~400-420whp should be plenty for now, and I guess if I need a little more later I could just change to a larger exhaust housing.

Thanks a ton for the help!

busa4

i didnt see this comment. are you sure this is a 80 a/r compressor side? 80 a/r with a 48 a/r exhaust side doesnt sound right. 80 a/r compressor side is massive. i have a 70 a/r compressor side and an 86 a/r exhaust side at home right now and its massive turbo. verifiy the exhaust and compressor air ratio's.

superbike81

I'm just going by the pictures. Am I mixing up the exhaust side and the compressor side? Like I said I'm a bit of a turbo tech noob. I know the basics.

I enlarged the image using the Photoshop interpolater enough to where I could clearly read 0.80 A/R next to "Garrett". Then if you look at the last picture, the top left, it says .48 right next to one of the studs.

Does that mean 0.80 A/R compressor housing and .48 exhaust housing?