Jump to content
SAU Community

Recommended Posts

Quite a reasonable outcome. Torque curve below 4500rpm would be more pleasing if it was filled out a bit more.

Stock 25DET turbo fitted? What boost level?

Sounds like the exhaust is relatively de-restricted too; noise levels not over the top?

There's a little bit of literature out there about high compression and forced aspiration that guides on effective static compression. Basic outcome is that there is a boost level at which your 10:1 engine will see a rapid increase in "effective" compression and head towards/over the detonation threshold. Be careful if you want to push further.

Link to comment
https://www.sau.com.au/forums/topic/204739-rb25det-dyno/#findComment-3626779
Share on other sites

Quite a reasonable outcome. Torque curve below 4500rpm would be more pleasing if it was filled out a bit more.

Stock 25DET turbo fitted? What boost level?

Sounds like the exhaust is relatively de-restricted too; noise levels not over the top?

There's a little bit of literature out there about high compression and forced aspiration that guides on effective static compression. Basic outcome is that there is a boost level at which your 10:1 engine will see a rapid increase in "effective" compression and head towards/over the detonation threshold. Be careful if you want to push further.

8.5psi but i've added a turbo elbow downpipe,tubular manifold and splitfire coilpacks and thats it i'm hoping i have not got to lower the boost as it will raise up
Link to comment
https://www.sau.com.au/forums/topic/204739-rb25det-dyno/#findComment-3626797
Share on other sites

thats pretty respectable.

im a bit picky. but i would try to get that torque curve smoothed out.

p.s. bloody good work on the intake manifold. never thought of doing that. saves $1000+ when u dont need a greddy plenum

:)

Link to comment
https://www.sau.com.au/forums/topic/204739-rb25det-dyno/#findComment-3627494
Share on other sites

thats pretty respectable.

im a bit picky. but i would try to get that torque curve smoothed out.

yeah but remmeber this is a dynapack dyno which gives different looking graphs, more emphasised than DD they are more sensitive... in a good way. Hence why i ordered one :ermm:

p.s. bloody good work on the intake manifold. never thought of doing that. saves $1000+ when u dont need a greddy plenum

:banana:

yeah its actually not great, in this application it will suffice but we flow tested and thermo-coupled a couple and there is a huge variance in flow to cyls 1 thru 6... a big differrence. there is just no real way of doing it properly, without going to another top half or complete plenum.

Link to comment
https://www.sau.com.au/forums/topic/204739-rb25det-dyno/#findComment-3628039
Share on other sites

thats pretty respectable.

im a bit picky. but i would try to get that torque curve smoothed out.

p.s. bloody good work on the intake manifold. never thought of doing that. saves $1000+ when u dont need a greddy plenum

:D

i doubt that torque curve could get much better. Most of the de+t setups have all the timing ripped out down low to help it stop pinging when its coming onto boost because of the cr.

Not a bad result though

Link to comment
https://www.sau.com.au/forums/topic/204739-rb25det-dyno/#findComment-3628862
Share on other sites

yeah but remmeber this is a dynapack dyno which gives different looking graphs, more emphasised than DD they are more sensitive... in a good way. Hence why i ordered one :D

yeah its actually not great, in this application it will suffice but we flow tested a couple and there is a huge variance in flow to cyls 1 thru 6... a big differrence. there is just no real way of doing it properly, without going to another top half or complete plenum.

theres lots of these plenums over here with no probs,and theres no way you would get as much power from it as you would a greddy one because its only got a standard throttle body,i have got a greddy type one but theres no point in using it until i lower the cr or blow it up and put a rb25det engine in it or if i smash the car i'll just buy a gtst and swap the bits over and in the meantime its all fun

Link to comment
https://www.sau.com.au/forums/topic/204739-rb25det-dyno/#findComment-3629120
Share on other sites

Looks dodgy to me. Still using the stock intake runners, which are designed to take the feed from the middle of the plenum.

when under boost the whole plenum is pressurised and not all intake valves open at once these intake runners are designed to suck not have air forced in them,i've heard on a forum somewhere theres been tests on these mods and the greddy one only took over at high bhp can't remember what the figure was or where it was but this engine will never get great figures with a high cr,ah and it costs nothing to do if you know a welder

Link to comment
https://www.sau.com.au/forums/topic/204739-rb25det-dyno/#findComment-3629121
Share on other sites

Check out this little guide

post-19642-1202336625_thumb.jpg

High compression forced aspiration cars are a little (lot) more fussy when it comes to making them detonation proof. That high effective static compression ratio indicator shows that a 10:1 engine will probably take a LOT less timing across the entire range of on-boost load. So in some respects what's being gained through the compression is being lost through comparatively retarded timing when looking at the 9:1 DET spec.

i doubt that torque curve could get much better. Most of the de+t setups have all the timing ripped out down low to help it stop pinging when its coming onto boost because of the cr.

That's what it is all about. :D

and in the meantime its all fun

I agree, and while it may lack a bit of the bling etc, if it works effectively and you suffer no driveability or reliability at this level of tune then run with that manifold setup. Not how I would do it, but that's just my view.

this engine will never get great figures with a high cr,ah and it costs nothing to do if you know a welder

FWIW, below is a graph of my DET with light mods and small-spec high flow. 300hp, with boost peaking at 13psi and tapering to 12psi. If you have 10 minutes, plot the points from one graph to another (yeah, I know, not directly comparable...) but you can pretty much see the difference. Same sort of max power number, but the 9:1 engine has bucketloads more from 3200-5800 where you drive it.

post-19642-1202336677_thumb.jpg

That is a function of the mass flow capacity of the turbocharger at differing pressure ratios - the high comp engine just won't let you pump too much in before it reacts with knock. :)

Hope that adds constructively to your setup and understanding differences.

Link to comment
https://www.sau.com.au/forums/topic/204739-rb25det-dyno/#findComment-3629243
Share on other sites

Check out this little guide

post-19642-1202336625_thumb.jpg

High compression forced aspiration cars are a little (lot) more fussy when it comes to making them detonation proof. That high effective static compression ratio indicator shows that a 10:1 engine will probably take a LOT less timing across the entire range of on-boost load. So in some respects what's being gained through the compression is being lost through comparatively retarded timing when looking at the 9:1 DET spec.

That's what it is all about. :no:

I agree, and while it may lack a bit of the bling etc, if it works effectively and you suffer no driveability or reliability at this level of tune then run with that manifold setup. Not how I would do it, but that's just my view.

FWIW, below is a graph of my DET with light mods and small-spec high flow. 300hp, with boost peaking at 13psi and tapering to 12psi. If you have 10 minutes, plot the points from one graph to another (yeah, I know, not directly comparable...) but you can pretty much see the difference. Same sort of max power number, but the 9:1 engine has bucketloads more from 3200-5800 where you drive it.

post-19642-1202336677_thumb.jpg

That is a function of the mass flow capacity of the turbocharger at differing pressure ratios - the high comp engine just won't let you pump too much in before it reacts with knock. :)

Hope that adds constructively to your setup and understanding differences.

is that bhp at the hubs or the fly,and i see what you mean about the graph and thanks but i'm still going to see if it'll go to 12psi and in the meantime i'm looking at buying a gtst engine to rebuild,and whats your opinion on water injection,thanks john
Link to comment
https://www.sau.com.au/forums/topic/204739-rb25det-dyno/#findComment-3631658
Share on other sites

With a hood water/meth injection system, 12 psi should be a really good thing, better than a DET with the same setup. The dyno graph comparison only shows half the story, as your motor should make more torque than the DET when not at full throttle, and return better equivalent fuel economy.

Link to comment
https://www.sau.com.au/forums/topic/204739-rb25det-dyno/#findComment-3631668
Share on other sites

Agreed. WI would be very highly desirable (essential) if you want to run to higher boost levels and keep the thing away from knock. That then places a big demand on system reliability, and fail-safe protection. Some systems offer flow blockage indicators and boost control interface to help keep things safe if you do encounter water flow failure.

The off-boost torque, and potential fuel economy difference is definitely a +ve for this configuration, but it's worth grasping the whole picture for high comp + forced aspiration. You might make another 20 or 30 rwhp with higher boost, but pushing it towards the edge of sensible limits. Getting really good results beyond that 300hp is going to take some thought and careful tuning. I've looked very carefully at the 25DE piston design, and my opinion is that there are some little sharp edges around those valve cut-outs that are not knock-friendly.

The other issue I'd be aware of is what Nissan did NOT put into the DE - oil squirters under the piston, and the dinky oil heater/cooler. They obviously felt it necessary to do something to remove heat from the piston crowns in the DET version in the name of reliability. WI would take care of that to some extent, but just be wary if you pushed the DE+T too hard, too long. Very good streetable combination, but you'd need to know where its weaknesses are when leaning on it for more.

Edit: that dyno sheet shows power at the wheels.

Edited by Dale FZ1
Link to comment
https://www.sau.com.au/forums/topic/204739-rb25det-dyno/#findComment-3631851
Share on other sites

when under boost the whole plenum is pressurised and not all intake valves open at once these intake runners are designed to suck not have air forced in them,i've heard on a forum somewhere theres been tests on these mods and the greddy one only took over at high bhp can't remember what the figure was or where it was but this engine will never get great figures with a high cr,ah and it costs nothing to do if you know a welder

It doesn't "look" like it would flow evenly. Don't have any evidence to back it up.

It would be good if it does because I've been looking for a cheap set-up with shorter intercooler piping.

Link to comment
https://www.sau.com.au/forums/topic/204739-rb25det-dyno/#findComment-3632388
Share on other sites

It doesn't "look" like it would flow evenly. Don't have any evidence to back it up.

It would be good if it does because I've been looking for a cheap set-up with shorter intercooler piping.

nothing to back it up but theres a few over here been running them for years with no probs and a greddy one looks like its got less volume in it,theres no doubt the greddy is better mainly because you can fit a bigger throttle body

Link to comment
https://www.sau.com.au/forums/topic/204739-rb25det-dyno/#findComment-3634095
Share on other sites

Plenum's with I6's are bout flow equality, not outright MASS, IMO

The fact ppl are using modded stocky's to make a lot of power and reliably is simply an indicator to me they're loosing a deal of power having to tame fuel & ignition to suit the lowest cylinders det threshold.

As URAS said, with these modded stock manifolds, you really would need to trim each cylinder with thermo couples / WB sensor... to get the best from it.

High comp and boosted setups require v.good manipulation of cyl pressures, assuming you dont cheat and use WI hahahaha jk.

Good result John

Link to comment
https://www.sau.com.au/forums/topic/204739-rb25det-dyno/#findComment-3634143
Share on other sites

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


  • Similar Content

  • Latest Posts

    • Update 3: Hi all It's been a while. Quite a lot of things happened in the meantime, among other things the car is (almost) back together and ready to be started again. Things that I fixed or changed: Full turbo removal, fitting back the OEM turbo oil hardlines. Had to do quite a bit of research and parts shopping to get every last piece that I need and make it work with the GT2860 turbos, but it does work and is not hard to do. Proves that the previous owner(s) just did not want to. While I was there I set the preload for the wastegates to 0,9bar to hopefully make it easier for the tuner to hit the 370hp I need for the legal inspections that will follow later on. Boost can always go up if necessary. Fitted a AN10 line from the catch can to the intake hose to make the catchcan and hopefully the cam covers a slight vacuum to have less restrictive oil returns from the head and not have mud build up as harshly in the lines and catch can. Removed the entire front interior just shy of the dashboard itself to clean up some of the absolutely horrendous wiring, (hopefully) fix the bumpy tacho and put in LED bulbs while I was there. Also put in bulbs where there was none before, like the airbag one. I also used that chance to remove the LED rpm gauge on the steering column, which was also wired in absolute horror show fashion. Moved the 4in1 Prosport gauge from sitting in front of the OEM oil pressure gauge to the center console vents, I used a 3D printed vent piece to hold that gauge there. The HKB steering wheel boss was likely on incorrectly as I sometimes noticed the indicator reset being uneven for left vs. right. In the meantime also installed an airbag delete resistor, as one should. Installed Cube Speed premium short shifter. Feels pretty nice, hope it'll work great too when I actually get to drive. Also put on a fancy Dragon Ball shift knob, cause why not. My buddy was kind enough to weld the rust hole in the back, it was basically rusted through in the lowermost corner of the passenger side trunk area where the wheel arch, trunk panel and rear quarter all meet. Obviously there is still a lot of crustiness in various areas but as long as it's not rusted out I'll just treat and isolate the corrosion and pretend it's not there. Also had to put down a new ground wire for the rear subframe as the original one was BARELY there. Probably a bit controversial depending on who you ask about this... but I ended up just covering the crack in the side of the engine block, the one above the oil feed, with JB Weld. I used a generous amount and roughed up the whole area with a Dremel before, so I hope this will hold the coolant where it should be for the foreseeable future. Did a cam cover gasket job as the half moons were a bit leaky, and there too one could see the people who worked on this car before me were absolute tools. The same half moons were probably used like 3 times without even cleaning the old RTV off. Dremeled out the inside of the flange where the turbine housing mates onto the exhaust manifolds so the diameter matches, as the OEM exhaust manifolds are even narrower than the turbine housings as we all know. Even if this doesn't do much, I had them out anyways, so can't harm. Ideally one would port-match both the turbo and the manifold to the gasket size but I really didn't feel up to disassembling the turbine housings. Wrapped turbo outlet dumps in heat wrap band. Will do the frontpipe again as well as now the oil leak which promted me to tear apart half the engine in the first place is hopefully fixed. Fitted an ATI super damper to get rid of the worn old harmonic balancer. Surely one of the easiest and most worth to do mods. But torquing that ARP bolt to spec was a bitch without being able to lock the flywheel. Did some minor adjustments in the ECU tables to change some things I didn't like, like the launch control that was ALWAYS active. Treated rusty spots and surface corrosion on places I could get to and on many spots under the car, not pretty or ideal but good enough for now. Removed the N1 rear spats and the carbon surrounding for the tailpipe to put them back on with new adhesive as the old one was lifting in many spots, not pretty. Took out the passenger rear lamp housing... what do you know. Amateur work screwed me again here as they were glued in hard and removing it took a lot of force, so I broke one of the housing bolts off. And when removing the adhesive from the chassis the paint came right off too. Thankfully all the damaged area won't be visible later, but whoever did the very limited bodywork on this car needs to have their limbs chopped off piece by piece.   Quite a list if I do say so myself, but a lot of time was spent just discovering new shit that is wrong with the car and finding a solution or parts to fix it. My last problem that I now have the headache of dealing with is that the exhaust studs on the turbo outlets are M10x1.25 threaded, but the previous owner already put on regular M10 nuts so the threads are... weird. I only found this out the hard way. So now I will just try if I can in any way fit the front pipe regardless, if not I'll have to redo the studs with the turbos installed. Lesson learned for the future: Redo ALL studs you put your hands on, especially if they are old and the previous owners were inept maniacs. Thanks for reading if you did, will update when the engine runs again. Hope nothing breaks or leaks and I can do a test drive.
    • No those pads are DBA too  but they have colors too. I look at the and imo the green "street" are the best.
    • I’m not sure what happened I told them about sonic tunes free OTS tune and the next the I know .. I was booted..   To funny 
    • Yea - I mean I've seen my fuel pump which is decades old and uh, while I'm not saying this with real knowledge... but I sure get the ick at using anything in the fuel system that produced the state of that pump. Many years ago I went through multiple pumps (and strainers) before I dropped the tank to clean it out with extreme violence. I'm talking the car would do maybe 50km before coming to a halt, which resulted in me cleaning out the filter with some brake cleaner and going on my way. None of my stuff ever looked like what came out of your fuel tank. I don't think I'd be happy with it unless every single component was replaced (or at least checked/cleaned/confirmed to be clean here).
    • I'm not going to recommend an EBC pad. I don't like them. Just about anything else would suit me better. I've been using Intima pads for a while now.
×
×
  • Create New...