HKS GT-RS Turbo kit

[Daniel san]

Although looking at the same graph in their book, it does say that it's (the stock s14 unit) running only 0.75bar with standard everything, so I guess that explains it.

The B8446 shown runs 740's, with their ecu and cams, at 1.2bar.

Edited to say that I really should have read all your post in the first place Papa, lol

[Papa Lazarou]

On a side note I think the B8446 is kick ass. I reckon it'll very comfortably support over 400 hp at just a little more boost than they are running there and should still be happy being cranked up to give hp's in the mid 400's..

[steve(s14a)]

Originally posted by Papa Lazarou
This is a graph for Tomei's ARMS turbo's. The ARMS B7652 is to all intents and purposes identical to the HKS GT-RS. Same wheels (52 trim GT35 comp, 76 trim GT25 turbine) same spec housings, it even looks the same.



The spec for the middle one (B7652) is as follows - S14 engine (w/ NVCS), Tomei 555cc injectors, Tomei ECU, Z32 MAFS, Tomei Poncam (256, 256), Uprated fuel pump, 1.2 kg/cm2 boost.

The Standard turbo on the graph is at 0.75 kg/cm2 boost and stock cams.

It should give you a very good idea of what to expect.

That's fair enough Papa, but HKS are known for always underestimating their turbos. So why for the GT-RS are they apparently massively overestimating?

It just makes no sense for them to do that.

Surely if a tuning firm as respected as HKS claims a figure, and after extensive questioning by various people (inc. myself), still standby that figure, we should give it credit?

Here is their graph from the Japanese website (although I'm sure you've already seen it! )




Specs are S14 with:

1/ 256 inlet and 256 exhaust cam
2/ Racing Suction intake
3/ Hiper Muffler
4/ Front Pipe
5/ SS Exhaust Manifold
6/ S Type intercooler
7/ 1.2kg/cm2 boost

(as a side note, perhaps the car using the tomei turbo was low on hp due to lack of SS ex manifold? As the original is not good for any more than 370 I believe)

[Papa Lazarou]

I wait to see your results It would be nice if true as you don't even need to upgrade the headgasket to run 1.2 bar. So its a very cheap way to 400 hp in terms of labour costs etc. You could substitute most of the HKS parts for cheaper items.

[steve(s14a)]

I admit 1.2 bar does seem a bit low?

I'm expecting to have to run 1.5 bar for that, with possibly high boost of 1.8 bar for about 425bhp for the odd drag strip run etc.

But it's all pie in the sky figures until someone tries huh?

It's going to have to wait for someone else to have a go though, cause I don't trust the pistons to cope with more than 330bhp long term, and frankly I don't have the cash for an engine rebuild!

[Daniel san]

I think you'l find with the right turbo, cams, injectors, pump, gasket, etc etc and most importantly, ecu map, the SR will take close on 400hp no probs.

[steve(s14a)]

Originally posted by Dan_BlitzedS14
I think you'l find with the right turbo, cams, injectors, pump, gasket, etc etc and most importantly, ecu map, the SR will take close on 400hp no probs.

Not meaning to argue, (although I do like a good arguement! ) but I have been advised by ND and HKS that 350 is right on the limit of the pistons; and at that power, sooner rather than later, they will fail.
If someone were to offer me a package that included a years guarantee on the build that did not necessitate forged pistons, I would snap it up like a rabid dog!

Unfortunately I haven't found anyone willing to do that yet

[Daniel san]

There are a LOT of guys in Japan running 380hp with a thicker head gasket and have been for a reasonable amount of time. I think it's fair to say that if you drove it hard on the road or track for any length of time, you'd run into problems, but opening it up now and again and for a 1/4 at a time shouldn't prove any problems at all.

[steve(s14a)]

Originally posted by Dan_BlitzedS14
There are a LOT of guys in Japan running 380hp with a thicker head gasket and have been for a reasonable amount of time. I think it's fair to say that if you drove it hard on the road or track for any length of time, you'd run into problems, but opening it up now and again and for a 1/4 at a time shouldn't prove any problems at all.

Exactly. It's that uncertainty of the point of failure, that necessitates it against being a wise choice for a day to day car.

I know it can take more than 350bhp, but for how long? That's too much an uncertain variable, as Richie found out with his old car .

[Papa Lazarou]

With due respect that same car also melted a set of forged pistons at a later date.... I think theres got to be the possiblilty something wasn't set up right.

[Papa Lazarou]

I have never seen a 330 hp limit on stock internals on anywhere apart from this forum!!

[Daniel san]

Good point Papa and you're right, it is only here you find a limit suggested of 330ish hp. I go by the Japs more than anyone else> If I didn't already have forged, I'd try blowing 400 with a 2835R and see what happens, assuming that I'd have the cash set aside to put right anythig that goes wrong.

[steve(s14a)]

Originally posted by Papa Lazarou
With due respect that same car also melted a set of forged pistons at a later date.... I think theres got to be the possiblilty something wasn't set up right.

Well I just like to err on the side of caution. As I have said, if a tuner is confident enough to provide me with such a conversion and some sort of guarantee, then I'd be more than happy.

But where are the proven 350bhp+ 2*****s that have done 15,000-20,000 miles since?

I know of none.

And yes, I do know of 330 conversions that, without head gaskets and pistons, have done similar mileages.
Thus I have faith in that conversion, as it has been proven.

To re-iterate, I have no doubt the engine can take it, I am only worried for how long

[Daniel san]

At the end of the day, you're right to go the piston route for reliability and it's certainly cheaper to have someone pull apart the block and fit this and that than it is to have them strip down and investigate first. Trust me

[steve(s14a)]

Originally posted by Dan_BlitzedS14
Good point Papa and you're right, it is only here you find a limit suggested of 330ish hp. I go by the Japs more than anyone else> If I didn't already have forged, I'd try blowing 400 with a 2835R and see what happens, assuming that I'd have the cash set aside to put right anythig that goes wrong.

Exactly. If you have the cash just in case, then why not?

But the fact that you would only try if you had the cash as a backup, tells the whole story in itself

And that is not to call you a chicken, cause I'm the biggest chicken of the lot!

[steve(s14a)]

Originally posted by Dan_BlitzedS14
At the end of the day, you're right to go the piston route for reliability and it's certainly cheaper to have someone pull apart the block and fit this and that than it is to have them strip down and investigate first. Trust me

Too right

[Daniel san]

Originally posted by Steve(S14a)
But the fact that you would only try if you had the cash as a backup, tells the whole story in itself

And that is not to call you a chicken, cause I'm the biggest chicken of the lot!

Sure, and I don't take it as such either

Only a fool would push his motor to the limit in such a way, without the resources to fix that which proves a weak link, particularly for the benefit of everyone else!

[steve(s14a)]

Perhaps I should edit out that chicken bit?

the idea of peeps now thinking i'm some sort of grotesque feathered animal with two legs is not so appealing!

[Daniel san]

Surely your avatar says it all mate, doesn't it?

[steve(s14a)]