Jump to content
SAU Community

Atr43ss-2 Prototype Initial Tune 250rwkws 18psi<2500rpm, Stupidly Responsive


Recommended Posts

All this talk of RPM vs load vs PSI is making me dizzy.

Here's one for the tuners out there with a dyno.

Strap a car car down and do a full power run through all the gears and post the results. I'd like to see power, torque and manifold pressure. It would help to paint a clearer picture of how a turbo car makes power in relation to boost, RPM and load.

Anyone willing and able?

EDIT: Im happy to donate my car for a few hours if required too - r33 GTST with FMIC, exhaust and pod - everything else stock.

  • Replies 118
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Posted Images

All this talk of RPM vs load vs PSI is making me dizzy.

Here's one for the tuners out there with a dyno.

Strap a car car down and do a full power run through all the gears and post the results. I'd like to see power, torque and manifold pressure. It would help to paint a clearer picture of how a turbo car makes power in relation to boost, RPM and load.

Anyone willing and able?

EDIT: Im happy to donate my car for a few hours if required too - r33 GTST with FMIC, exhaust and pod - everything else stock.

Come on, someone do it!

STAO - how would a pair of these go in a RB26dett? bolt-on.. possible? thoughts?

cheers

Naa they will be way too laggy to run as twin on a RB26det (1.3L / Turbo vs 2.5L / Turbo). We can high flow them with 2860RS cores. will deliver better result.

Naa they will be way too laggy to run as twin on a RB26det (1.3L / Turbo vs 2.5L / Turbo). We can high flow them with 2860RS cores. will delivery better result.

Wouldn't that be the same as buying a 2860-9 or similar?

Or are the results different?

Apologies for hijacking the thread.

Wouldn't that be the same as buying a 2860-9 or similar?

Or are the results different?

Apologies for hijacking the thread.

RS has different turbine wheel. Probably not much more in HP, but lot more torque. We've been using those 2x types of CHRAs in our 300zx turbo developments. Very noticeable amount of difference on road, The RS gives stronger pulling sensation while both turbos made within 2KWs difference.

You will have to try the dual port actuator out for yourself.

I haven't personally used one, but my brother did on his Gt3040 turbo.

Sadly in his case it didn't work and he had to use a 1.5 bar standard style actuator to

get the 26psi he wanted.

turbo looks interesting, be good for a auto stagea maybe

cheers

darren

You will have to try the dual port actuator out for yourself.

I haven't personally used one, but my brother did on his Gt3040 turbo.

Sadly in his case it didn't work and he had to use a 1.5 bar standard style actuator to

get the 26psi he wanted.

turbo looks interesting, be good for a auto stagea maybe

cheers

darren

I wouldn't thought this theory works as my actuator's spring pressure is already greater then intake manifold pressure. Obviously actuator's rod force is not based on the sum of both pressures, but only the strongest.

Based on the physics of: force = Pressure x Area

I've trailed it by reducing the "Area" which is the wastegate port size. This has worked. boost is holding at 18psi perfectly, I’ve also engineered it as adjustable suiting larger sized engines. I will find out the effects it has based on the end results next week..

How ever this is still not my main goal of stabilizing exhaust manifold pressure.

So I've made a rough model of have an external wastegate integrated into an internal gated setup.

1.jpg

2.jpg

3.jpg

4.jpg

If this works as expected it will be able to keep the top end steady while picking up another 10~15KWs. I'm not sure if this is counted as "Road legal" assuming this is some how internally wastegate.

RS has different turbine wheel. Probably not much more in HP, but lot more torque. We've been using those 2x types of CHRAs in our 300zx turbo developments. Very noticeable amount of difference on road, The RS gives stronger pulling sensation while both turbos made within 2KWs difference.

Interesting, might be in touch once I save up some money...which could take quite a while :)

i dont see the point of a ghetto external gate onto an internal gate turbo

isnt the point of an external gate setup

so that all of the flow/prssure on the exhaust side runs through the entire housing snail to give the best possible flow/veloicity and drive the compressor harder/quicker and when target is reached, the external gate releases back pressure to control flow.

vs internal gate

all of that flow/pressure runs through the smaller exhaust housing as it has to account for internal wastegate bypass

it's a reasonable expectation that an external gate setup always comes on boost quicker and has better response

but its also resonable to expect more cost involved

i see no value or gain in control of boost etc in an internal to external ghetto mod

The Pressure is dumped out of the turbine housing and plumbed back into the exhaust side. Its not re-circulating back into the snail. Same setup as plumb back external gate.

Its a prototype model, We'll find out if it works or not soon. :)

The Pressure is dumped out of the turbine housing and plumbed back into the exhaust side. Its not re-circulating back into the snail. Same setup as plumb back external gate.

Its a prototype model, We'll find out if it works or not soon. :banana:

So the internal gate is just sitting there? Not dissing your design at all just wondering; promising looking turbo.

I'm not too sure if the gate will work or is the best solution since I don't see how much different from an internal waste gate plumbing back like that other than the fact the external waste gate can probably accommodate for larger volume of gas but AFAIK it really shouldn't be necessary at this power range. And even then, you're just putting the gas back into the turbo housing again anyway? (correct me if wrong)

I think it's that the exhaust housing is too small to accommodate for the engine at the higher revs and boost in the current situation and therefore it chokes at the turbine side of the turbo. If you want to keep the responsiveness (which I definitely would like to see) then increasing the size of the rear housing is out of the question or really makes things much more complicated at least. Though, have you thought of methods of moving the air out of the turbo faster?

I mean, could it be as simple as a better front/dump pipe, cat, exhaust?

Dyno running with no dump pipe/front pipe just to test can confirm/disprove my hypothesis.

To add to the discussion regarding boost/power in earlier gears in the previous pages of this thread. My understanding is that an engine will suck up an amount of air equal to:

V_air / minute ~= Displacement x RPM x Absolute pressure

And proportionately an amount of exhaust fumes is produced. So no matter what gear you're in the turbo will behave the same.

It is true that a turbo might not be able to spool up fast enough in the lower gears though.

Also, from my understanding, gears ratio's smaller than 1:1 (engine:gear) you're multiplying the amount of torque (rotational acceleration) at the wheels.

This is why they dyno your car in fourth gear (1:1). So you can comfortably say when you have 200kw ATW, you have 200kw's + unknown amount of power lost due efficiencies at the engine. Without having to do a chunk of maths.

i.e.

ATW_Power = Flywheel_Power - (Work / sec)

Work in this case is the drive train.

What all that means is that it doesn't matter what gear you're in when it comes to the performance of the engine and consequently turbo.

My 1c

  • 4 weeks later...
  • 2 weeks later...

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Latest Posts

    • When you crank your car, and hit it with a timing light, can you see a steady crank timing?
    • Oh, forgot to add, A few months ago I was getting mixture codes and the car was using crap loads of fuel. You could smell the unburned fuel in the exhaust, it was crazy strong. Economy was over 17.5 l/100 and usually around 19. I smoked the engine and found a leaky CCV hose which I replaced and then I replaced my two pre cat O2 sensors, I also replaced the MAF. This fixed my mixture codes and improved my exonomy but I'm still 14 - 15 l/100 when pottering about town so something is still amiss. Throttle response is much better and it has more pep but I'd like to know why it's still so thirsty (and I'm hoping that whatever it is gives me a bit more poke).    
    • Car is on factory injectors/z32 maf/ q45 throttle body/ z32 ecu with nistune 
    • Hello all, currently finishing up a rb25 swap into my s14. Having issues with starting, car has spark (confirmed by pulling a plug and watching it spark), has fuel(confirmed by checking pulse/voltage at injectors all spark plugs are soaked in fuel). Car cranks over and pops into the exhaust with a heavy fuel smell but no attempt to start or run, I have torn the timing cover off and triple confirmed timing, turned the CAS in multiple spots both directions, attempted to start with coolant temp and maf unplugged, checked my fuel lines and made sure they weren’t backwards, checked voltage at cas/injectors/coilpacks, made sure all the grounds in the harness are connected and added a few grounding straps (1 from chassis to block, 1 from chassis to head, and 1 from chassis to igniter chip) I am getting stumped here. As a last ditch effort I made a full grounding harness tonight that’s going to run from the battery and add an extra ground from the battery onto the coil pack harness/igniter chip/ intake manifold/ Wiring specialties harness ground/ and alternator. I’m hoping maybe the grounding harness will fix it here but posting here to see if anyone has any other ideas on what else I can check. My fuel pressure is unknown right gauge will be here tomorrow.  IMG_3206.mov
    • yeah I was shocked when I checked my spare OEM on and as below that's how they come from Nissan. (side interesting note new NEO gearbox and replacement park lack the brass bush on the tips and its just all alloy) unsure about damage to the box currently back at 1110 to be pulled down/inspected and selector fork replaced as he built it previously and given the never before seen failure on his billet forks he is replacing it under warranty. He said he has used always OEM the keyway tab without issue for years so it could be an unlucky coincidence. I did talk to him about the sharp corners and stress concentration too. Re: hard shifts i got 7+ years out of the OEM one and the fork itself failed not the keyway. so could be bad luck as I said or an age thing + heat cycles in box and during fabrication of billet?
×
×
  • Create New...