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Sr20det ps figures


Zach

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I've seen a handful of sr's making 320hp on F*** all boost (16-18) over the past few years and recently Was looking at my brothers dyno sheet from 1 year ago and realized he's got one too ( 250kw still going strong and thrashed weekly ) and he's only running 17psi with unbranded shitty 3rd hand supporting mods & a Garret ball bearing turb.

 

I seem to remember never ever losing to sr20dets in my above average gc8 back when I was boy racing even rolling start pulls. I always laughed at the rb and sr boys blowing there slow cars up while my ej out thrashed out raced and out lived them and Id blow my trumpet all the time about it. I sure as hell was not making 250kw on that old gc8 running similar boost untuned.  On 17psi his silvia pulls considerably harder than my wrx did he tells me and he's not a liar in the least so I believe him. I've come to understand I actually know F*** all about car's so I hope im not sounding like a dumb ass but after a quick google the amount of work people are putting into there ej205's to hit the 250kw considerably more than my brothers. Do sr's make more power than us or have I just happen to see a few unicorns?  Is it true? do sr's make better power than ej's alot easier?  I always thought sr's were overrated but now It's got me stumped wtf. Thats a big difference in power. Can anyone explain? Im happy to give more info about both cars.

 

I have dyno sheets of his sil but dont know how to upload it.

 

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idk much either but that power curve looks pretty solid. I imagine those rwd cars must be pretty light too. All engines are different so some cars can get huge gains with a few mods. I dont know a lot about SRs tho.

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A lightly modified sti can make 220kW at the wheels including the extra drive train losses, 250 wkW with a garret doesn't sound like much (depending on the garret).

 

That curve looks like it holds power better up top than our ej20's from factory.

Edited by Jono24
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Thanks. I posted this because I wanted to have a open discussion about it with some people because its been on my mind and the people at my work dont care much for cars yet alone know about them lol so thanks for the imput there, the drivedrain loss, thats interesting point

 

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If I put a Garrett on a Subaru I would be pretty disappointed if I didn't end up with around 250kw as well.

 

You see lots of Silvias with that kind of power because it's simple to swap the turbos out on them for proper ones. In the Subaru world 99% of people are fart-arsing about with stock location barbie-doll hairdriers which will maybe get you to 240wkw downhill with a tail wind.

Long story short they don't mysteriously make more power than Subarus, for the most part a 2 litre 4-cylinder engine with the same compression ratio doesn't care about the arrangement of the cylinders, it's some pretty basic chemistry that results in power and the Datsuns aren't breaking the laws of thermodynamics any time soon.

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On 4/30/2018 at 9:45 PM, Gripless said:

Don't forget header length and heat losses add up, one of the reasons why the newer FA series has the front mount turbo.

 

im pretty sure the stock sti can hit close to 240 kW with the stock turbo ;)

 

On 17psi though? Seen a few subbies hitting 220'ish kw on trademe recently running low 22'ish psi

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Yes but that 22 psi is low down in the sub 4000rpm range as the Stock Wastegate actuator and pill can't hold more than about 15 psi well before the redline which is why the peak power isn't as high.

The area under the curve is about 30% greater which is what makes a car fast and drivable.

Peak power isn't everything

That plot you put up looks like it will drive like a modified vtec, nothing then everything like a switch.

 

I have a dyno plot here of a ej20 on 14 psi making 214 kW at the wheels. The plot is a straight line from 2500 up to 7250 rpm and 214 kW then flat to 8000 rpm.

 

 

 

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not an expert but couple obvious things going down here. this is very much an apples to oranges comparison

 

  1. rwd vs awd.. our awd subies have greater drivetrain loss, the dyno numbers being compared are at the wheels , hence we generally have to do a little more to squeeze more power
  2. not really fair to compare psi between different turbos (atleast from my limited understanding, not an engineer!) . different turbos will flow different rates of air (cfm) at same pressure level
  3. like boon said already, if you apply same turbo to both 2l engines then you're coming closer to a better comparison
  4. not familiar with the nissan community, but you mentioned they tend to get more power with less mods. we in subie community (atleast members of this forum) seem to care about longevity of our cars and do a lot of supporting mods for safety following turbo upgrades. for example one thing we pretty much have to do for street cars chasing higher power is switching to a front mount intercooler whereas many other cars get this from stock.
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2 hours ago, Gripless said:

Yes but that 22 psi is low down in the sub 4000rpm range as the Stock Wastegate actuator and pill can't hold more than about 15 psi well before the redline which is why the peak power isn't as high.

The area under the curve is about 30% greater which is what makes a car fast and drivable.

Peak power isn't everything

That plot you put up looks like it will drive like a modified vtec, nothing then everything like a switch.

 

I have a dyno plot here of a ej20 on 14 psi making 214 kW at the wheels. The plot is a straight line from 2500 up to 7250 rpm and 214 kW then flat to 8000 rpm.

 

 

 

That is the sorta of answer I was hoping would exist. I dont understand the intricates of dyno figures at all but what your saying makes sense to me. I think the subaru community does differ at large than the nissan scene as batbaruman said too

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Grap the dyno plot from @Niran build thread linked below. Look at the power at each 500 rpm and the power the car makes.

 

Even a stock turbo sti can push 145 kW at 3500 rpm while that car is still at 100 kW so you're almost 50% more power down low. Niran's already at 190 kW by 3500 rpm so almost double the power i.e. He wins.

 

Now if you draw an imaginary line from say 2000 or 2500 rpm to the peak power.

 

A) the plot should stay above that to be torquey and good to drive. It should start close and go up as vertically as possible then curve across to peak.

 

B) exactly on that line is like BMW and Audi nice linear smooth power.

 

C) If it stays below that line then rapidly come up like a string hanging under the two points the car will be peaky and S*** to drive daily.

 

that one you posted is all over the place so maybe ok to drive but a bit laggy under 4000 rpm as the turbo spools slowly.

 

 

if you take 10-15% for the header length and another 7-10% for drive train 4wd loss it's no as bad as it seems.

plus boxers are balanced motors and weight of the block is stuff all so there are advantages to be found.

 

oh yeah that's 254 kW on a stock turbo so some thing to think about even though it's a 2.5 sti.

 

On November 27, 2017 at 11:14 PM, Niran said:

 

MTiKZFO.jpg

 

 

Edited by Gripless
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I love subis, suby life all the way. But Nissans - SRs RBs etc, seem to be able to get more power easily in general. I mean look at their engine bay, so much easier to bolt on bigger turbos like mentioned earlier. But yeah stock STI turbos have really good spool and low down torque which makes them fun to drive. Was pleasantly surprised by mine as above.

 

In an ideal world id have both an r32 GTR and my STI.. Dreams are free xD

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well we all want power in different places also don't we. their cars being rwd i imagine they (for the most part) don't want turbos which are quite as peaky low down as ours from stock, think the original configurations with engine/turbo/drivetrain setups were to prioritise top speed on nissan vs pure acceleration on subaru

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@Batbaruman yeah exactly and also how you drive or race and the road conditions.

Linear power is pretty nice when it's wet and rainy or slow traffic compared to everything else it's all a trade off.

 

rally is all gears and most of the rev range 

race is mid to high rpm range once started some engine braking and mid corner throttle

drag is all redline and only enough rpm for gear rpm drop

 

But there is also the newer cars with si drive so you can have all 3 if you wanted. Or on an after market ecu or boost controller you can have the same.

 

 

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I think its all about what you want the car for I had a s14 with around 240kw at the wheels and have had a rb25det skyline also with the typical bolt on mods. IMO the silvia was like driving a automatic primera until it came on boost and then it turned into a twitchy little tin can and the skyline just spun the wheels everywhere until you hooked 4th gear and it caught grip. 

 

With the WRX even though I have a lot less power and most likely more weight I feel that the power band is a lot more enjoyable and the car feels a lot more rigid and you can throw it into a corner on a track without feeling like its twisting.

 

Al thought when slipway in wellington was open the skyline was a lot of fun! . 

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