Forced Performance Hta Turbos

[Lithium]

21 minutes ago, GTSBoy said:

Yeah, but Kinks has a 5.7L V8 in his R34.

Ahh gotcha 

[Lithium]

On 15/02/2024 at 8:35 AM, Lithium said:

I'll have to get some logs when I do a little bit more work on an R34 GT-R I've been helping set up.

So we had a bit of a session today and didn't have much chance to test it perfectly for the point of this thread but the theme seemed to be it can hit 1bar close enough to 4000rpm in 3rd gear, give or take a little and man it feels a lot perkier between 3000-4000 than the -5s.  

[Lithium]

On 15/02/2024 at 8:35 AM, Lithium said:

I'll have to get some logs when I do a little bit more work on an R34 GT-R I've been helping set up.  Stock engine, 272deg cams, and a divided hotside Pulsar G35 900 with .85a/r T4 divided hotside and it drives fantastic - it's enough of an improvement over the old -5s that no data is really needed from our point of view to make a call on whether it's more responsive under foot to drive but boost threshold is always a handy metric.  

I'm far from saying that the G35 would be a good choice for the kind of thing you're looking into, more what I'm suggesting is "G-series" turbos seem to respond very well to divided hotsides and middling a/rs (obviously ensuring that it's not so small as to choke the given setup).   If a static cam RB26 drives like this R34 does with a 80+lb/min turbo, then I can imagine a 60lb/min equivalent match on a VCT RB25 would be fantastic. 

Interesting (but I suppose not massively surprising) the dyno plot doesn't put this car across as THAT much better down low than it was with the -5s, the old "transient response" beast back with a vengeance.  I guess you'll have to take my (and every other person who has been in or driven it) word that the car is a completely different beast now, feels WAY more alive basically everywhere.   Holds power better, "wakes up" faster under foot.  It's generally a significantly faster and better car to drive, beyond what the plot shows.

Anyway, only changes here are swapping from low mount -5s to a Pulsar G35 900, and from a stock Nissan RB26 intake manifold to a Hypertune single throttle jobby.   On the dyno pull it doesn't really pick up noticeably harder until it's got about 10psi into it, then it gets from there up to target boost a good 500rpm earlier. 

Same boost, same fuel (98 pump gas), same dyno:

Note: This is both 22psi.  It's a stock RB26 aside from cams, the turbo was chosen for headroom - and there should be HEAPS in it with a built engine and ethanol flowing through it's veins.

Edited March 14, 2024 by Lithium

[Kinkstaah]

22 minutes ago, Lithium said:

Interesting (but I suppose not massively surprising) the dyno plot doesn't put this car across as THAT much better down low than it was with the -5s, the old "transient response" beast back with a vengeance.  I guess you'll have to take my (and every other person who has been in or driven it) word that the car is a completely different beast now, feels WAY more alive basically everywhere.   Holds power better, "wakes up" faster under foot.  It's generally a significantly faster and better car to drive, beyond what the plot shows.

This is what I was getting to with regards to the whole N/A V8 thing. A dyno shows the result as much worse, but in terms of how 'alive' the car feels afterwards, it's night and day, better in every way, there's no copium, I prefer my 280kw setup over my 430kw setup.

This was me doing predictions before I did the swap, I make about ~10kw more everywhere than the blue line, but chalk and cheese in terms of liveliness. I understand what Lithium is trying to say with his dyno graphs that look mostly the same in his case, but one is vastly superior in the real world. The blue line looks laughably bad on the dyno graph in my case, which really highlights the point.

People absolutely, absolutely, completely underrate how important transient response is to how much fun a car is, how it feels, and how much you can trust a car, which means you can drive the thing faster, and if you are going faster and using 70% of the throttle, and trusting, and pushing, it's a far more fun, complete, and faster experience than feeling like you can't go beyond 50% of your throttle use but damn your dyno plot looks great.