Right so the final results: The car was set up on the dyno and tuned to the limit as it was in previous outright power testing, same spark plugs, same type of fuel from same supplier (granted there could be minor discrepancies there as I have burned over 400L of fuel in testing and tuning alone!), weather conditions near enough identical. On the low boost setting of 9PSI the comparison is very obvious, with no other alterations to the car other than the fitting of bigger injectors and the Z1 2.5" boost pipe and intercooler kit it gained a maximum extra of around 30Kws at the hubs. (33.864 according to the dyno) The size of the injectors will NOT change power significantly at this level of boost and the tune was altered only in the mixtures to correct the tune for the new injectors. Air fuel ratios were set as close as possible to the same as before - you could barley see the two lines for the most part. Actual numbers are (rounded): ~275Kws on 9 PSI on standard sized pipes Z1 intercoolers and throttles. ~310Kws on 9PSI Z1 2.5" pipes and intercoolers + throttles. This result supports the previous experiment with the intercoolers and pipes mounted externally to the car where we recorded around 22Kw gain although using the smaller original Z1 intercoolers modified to 2.5" pipes. The previous testing showed that as boost increased the gain to be had on this particular car reduced and this was witnessed again on this car today with the following results: The amount of gain reduced and moved to the right of the graph compared to what was seen on the lower boost setting. This is the result of another restriction making its opinion heard - the poor little GT2560Rs can only do so much you know. In this case they belted out 419Kws at the hubs at 20PSI boost, peak boost was 22PSI but slowly tapered down from around 4500RPM. There is actually a little more left in the car by changing from the hotter plugs to something a little cooler but I couldn't do this while carrying out this testing as it would effect things enough to screw up the testing. We were tuning to the point where we could just here detonation then backing off two degrees - one way to ensure each tune change was set to a similar safety benchmark. (it's my engine I will thrash it if I want to!) ANYWAY what can be seen in the second graph is a minimal gain to 6000RPM but something worthwhile if you are chasing every last bit at the top. Ignore anything prior to 4000RPM as a different start speed was used so the first 1000RPM of those runs could be considered corrupt - although if we are sensible we can see it's only the first 500RPM that is significantly effected. There are two other cars that will undergo back to back testing of similar changes although unless we see something in stark contrast to what we have found here I see no need to post it. Just to reiterate the reason the overall peak power gain is so small is because the turbine housings are actually causing a serious restriction. IF this car had for example the GT2860RSs or GTX2863s etc then I would expect to see a much better gain at the top end. Oh looks like I've knocked Mad Mike from his spot on the dyno chart JP in a Mungyz sandwich now aye - oh and two kiwis either side of him :rofl:
Forgot to mention the injector duty cycle, on the previous testing that netted 556Hp at the hubs we had the 555cc injectors maxed out. With yesterdays testing we had 650cc injectors at 87% and making 560Hp at the hubs. No significant change in the HP output compared to fuel consumption therefore IMO no significant change in overall efficiency - for this car at this power level.
So why does the blue zed have an old plastic splash guard instead of a blingy aluminum one?? Tests were an awesome read, lots of valid info which I'm sure will help a lot of us. Cheers
I think I'm more impressed at what you got out of the 2560R's than all this pipe silliness I've been tossing up wether to put mine on or flog them off and go bigger. This is a big plus to the 2560's You got bigger valves in yours or just porting and cams?
As a turbo novice, I found this to be a good read. I don't think I'll be doing 500hp build, but the information is worth the read. Thanks.
Just porting and cams, I want more out of the turbos and I know there is a little bit left but I couldn't muck around with the other changes I need while all this was underway. I'm running 6s for the plugs, they should be 7s at this boost level so there are some ponies still in the stable there for sure, I COULD have done some work on the inlet and outlet pipes for the intercoolers to try and squeeze a tiny bit more there. The turbo inlet system is still a restriction, I have most of it sorted but the actual pipes on the front of the turbos are essentially stock, the turbos are running out of puff so any help in getting air in WILL make a difference. Just dyno queen shite now though - I like the 300Kw at 9PSI, for me that is fricken awesome and I'm really happy with it, I can go to a track day and beat the crap out of it literally all day long at that power and it'll take it and ask for more even at 15PSI it'll make massive power and do it easily. 20PSI for superlap though, comes on pretty early and hangs in right to the bitter end. Syntax_x I did actually have an ally one bolted on for a few minutes but decided just to leave the stock one on until I get some anodised ones done - they are next on the list of things to do
After seeing those results I am insanely looking forward to seeing what my gtxturbos put out ! (Note I am using stock intake size)
Sorry I missed this post. I wont be making and selling the pipe kits as there is a selection of vendors to choose from at present already. Impressed with the Z1 kit though
thread dig. very good read. I am contemplating doing this changeover. what I notice is that you say the gains are minimal for high boost applications. I plan on runnning 30psi E85 on my blitz turbo kit. same z1 intercoolers. my car launcheds around 4000rpm and shift light is set at 6400. would you think there would be a gain to be had going to 2.5" piping? my engine pretty much stays at 5000-6400 whole track. I will be using direct port nitrous aswell. thanks in advance.
Here's an actual test with the pipes in the car http://www.twinturbo.net/nissan/300...C-MASSIVE-SMIC-amp-25-Piping-results-PT1.html
Gains will change depending entirely on the set up, bigger turbos offer a different gain curve to smaller turbos etc etc.
I'm pretty certain I made it very clear before I did any testing why I was testing these myself on a hub dyno in a controlled environment and doing back to back testing in rapid fire IE: running the car in both configurations several times within a very short period of time. Later testing with the pipes fitted to the car confirmed the accuracy of this procedure.
I hope so, a mate over here just ran a 10.9 sec pass with his RB25DET powered R33 (2WD), it's a bit embarrassing with so many Z32s in Australasia & so few of them actually putting the numbers down at the strip & showing what these old dinosaurs can do.
Wouldn't be, the stock hitachi turbo in the R33 is ceramic and tends to annihalate the turbine wheel after 1bar of boost. Fastest stock turbo R33 was doing 11.6's @ 118mph with a 100 shot making ~300rwkw.
