Hey guys, Just wondering, are American dyno's ridiculously incorrect? I was just looking at this thread, and it looks like they're trying to claim 500hp @ 17psi on GT2860RS's http://www.twinturbo.net/nissan/300zx/forums/general/view/2506823/GTX-2860R-Dyno.html I mean, I'm running the same boost, on my car, with basically the same mods (minus the selin kit) and only made 420hp (313kw). And the 11ish-psi run they did made over 400hp Someone care to explain?
This is a long running topic, but basically the rule of thumb is US dyno figures are usually optimistic compared to Aus ones. Look at the kind of figures other cars with your mods are doing in Aus and compare 1/4 mile times. Generally this opens a big can of worms that has been done before a few times.
Garrett GTX turbos are more efficient at higher pressure ratios so will make more power than their GT counterparts with more boost. Also its not the 1/4 mile time but MPH that indicated your power, and from the few comparisons i've done i generally take off 10-12% off any american dyno figure.
Dear lord not this again haha. I had a 100+ comment argument on zshopmatts page on a picture of my zed regarding dyno results from American cars built the same/similar as mine and making 50-100hp more lol. My head hurts :/
American's claim 400-450 RWHP on stock turbos :/ massive load of shit. Not saying it CAN'T be done, people have done it with fancy setups and their MPH proves it, but they are claiming this on stock 20 year old stock engines with Ash spec massive coolers, 2.5" intake and a boost increase..... They'll tell you that every Australian car built doesn't have the breathing mods necessary to pull that extra 100-150hp and that our intercooler setups hinder power.
My favourite one. ..."without 2.5" intake your cars power will be severely limited..." Apparently they have access to better quality/octane fuels from pump there too :/
Its pretty funny because the two US zeds running 123MPH(~350rwkw) on stock turbos aren't even running those "breather mods" and all those US guys do is wank on about them like they are the be all and end all of making decent power.
Lol, what about that bloke I was arguing with who said that plenty of Aus zeds had gone overseas and ran low HP on an American dyno. I asked him like 15 times for proof and also explained that even if it did happen once, the sample space isn't big enough to draw a conclusion. Idiots, haha.
My favourite is when they not only pull 400rwhp on stock turbos, but on 91MON(95RON here). HA! i'd like to see ONE of these cars match the MPH on the strip.
Apparently they typically use Dynapack (hub) or Mustang. They must calculate power differently to Dyno Dynamics -probably a different "standard"
Simply put they use a standard that measures flywheel HP at the rear wheels. In Australia we prefer rear wheel actual. If you take the 500HP in the OP and take out a generic drive train loss of 15-20% you get 400-425HP.
Correct, brake horsepower is what they use in the UK. The americans measure rear wheel horsepower too. With all this 2.5" pipe nonesense, i'd like to see it done on a mild TT on stock boost before and after.
Yanks are crap artists, I stirred up the Z31 forum by basically telling them that their marvellous power figures were rubbish, which they were. I now have a pretty fair idea what is required to get 400whp from a VG33ET and it's pretty drastic stuff. Which they would not have a clue about.
Haha ok, i was wondering how there were so many 600+hp zeds over there with the exact same mods as the 500hp zeds here And woops i didn't realise they were GTX turbos..
In a nutshell: Every dyno is different, you will get varying results by changing brands & operators. The hub dyno is recognised as the most accurate dyno machine in the world as there is zero slip between the hubs and the dyno unlike the rolling road that can and does have issues with traction between the car and the machine. Some dynos use a rotating mass to load the engine, some use a type of brake, the brake can be electric or water or hydraulic - I'm sure other systems have been used also. If a dyno is capable of holding the car at given RPM points then it clearly has a win over those that can't when it comes to tuning the car accurately. To say the qtr mile is more accurate than a dyno is like saying pacing out a mile is better than using a GPS system or some other form of modern surveying system. The Qtr mile strip tells you how fast a car went & how long it took to cover a distance. It DOES NOT tell you the peak HP or torque, it DOES NOT tell you if a car has a wide spread of HP or nothing down low then heaps up top. You can't even get a remotely accurate figure from calculations based on weight of car etc as there are never any variables such as traction, wind speed, driver error etc taken in to account with the armchair expert equations out there. If I were to take a car designed for the salt flat speed record attempts and put it down a drag strip then use one of those HP calculators to work out the alleged HP of that car it would be wildly inaccurate because of the gear ratios & shear lack of acceleration that type of car has. Similar with the wild speedway cars that have mega HP but are designed for a very short track so run out of revs very quickly due to the gear ratios, your qtr mile calculator will insult the car with its lowball guesstimate. The same car fitted with a manual gearbox will net a different trap speed if it were fitted with an auto gearbox. Clearly a thinking man would NEVER take the qtr mile results over those from a well respected dyno machine and operator - squillion HP cars that simply can not be dynoed due to the lack of machinery to do it excluded. Case in point: Mere mere drag strip over here in NZ is going through a massive resurface operation (nearly complete) publicity information and news letters to those who use the track contain remarks on "quicker times, faster trap speeds" etc Please show me where the qtr mile HP calculators take in to account the track used, weather conditions etc .................... not going to happen is it.
