R32 Gtr Single Gt35r. Apexi's De-jetro A Good Choice?

[rb30gtr]

Thanks heaps for the opinions guys

Its on its way from Japan, HURRY UP.........

AAAARGHHHHHH

My front discs are all rusted, interior is all dusty...........

How many kws you guys recon I could go for?

Its a standard 26 with 650 injectors, gt35r bb (700hp)with 5omm external gate, and I will be running the dejetro.

It does although have a SAU sticker, and from what ive noticed that alone should give me at least 300rwkws, according to most of the bum on seat dyno heros.

[Gav]

Our race team tuner likens it to tuning with a normal Power FC where the AFM maxes out as soon as the boost target is achieved. All you have is RPM (and throttle position of course).

cheers

Sorry - I can't understand your logic? Why would the twin MAP sensors of the D-Jetro have less sensitivity than twin MAF sensors (AFMs) of a std PFC?

You are correct that at WOT and full boost, there should be little variation in manifold pressure, however I would expect little variation in AFM output voltage as well. So in effect they are both "two dimensional" at this point.

One exception is sudden closure/opening of the throttle bodies during gear change. I would expect that the D-Jetro would respond quicker here as it is measuring load right at the manifold and not way "upstream" of the induction tract where the AFMs are located. Large volume intercoolers and big diameter induction piping must surely amplify this effect.

Cheers

Gav

Edited March 21, 2006 by Gav

[Cubes]

You are correct that at WOT and full boost, there should be little variation in manifold pressure, however I would expect little variation in AFM output voltage as well. So in effect they are both "two dimensional" at this point.

I know from logging mine on the dyno via datalogit, airflow (afm volts) increase with rpm when at max boost.

As rpm increases so does airflow, its well know.

Plotting your engines airflow at various rpm's on a compressor map illustrates this.

On the topic of map sensors... How does it tell really how much air the motor is swallowing? For example, 1/4 throttle i'm up on 13psi, mash the throttle the boost is still on 13psi yet it pulls so much harder.

Obviously there is much more airflow=power due to open throttle.

Running map I would think this part throttle 13psi boost area would be running the same ign and fuel values as if it was receiving full throttle @ 13psi, as a result it will be rich and not running as much ign as it could, economy and part throttle acceleration would no doubt suffer?

Does that sound right? I have had sfa experience with map.

[Topaz]

A few of the WA guys have dropped the Wolf and gone for the DJetro, maybe try a post in the WA section. I am sure everyone would appreciate a run down on your experiences once it is tuned.

Cheers

I am getting my D-Jetro tuned by Ken at hyperdrive on the 28th

I hope its dones well and I don't have sensor problems :

He has told me they will need the car for a day for the install which includes a PRofec B as well...

[Gav]

I know from logging mine on the dyno via datalogit, airflow (afm volts) increase with rpm when at max boost.

As rpm increases so does airflow, its well know.

Plotting your engines airflow at various rpm's on a compressor map illustrates this.

On the topic of map sensors... How does it tell really how much air the motor is swallowing? For example, 1/4 throttle i'm up on 13psi, mash the throttle the boost is still on 13psi yet it pulls so much harder.

Obviously there is much more airflow=power due to open throttle.

Running map I would think this part throttle 13psi boost area would be running the same ign and fuel values as if it was receiving full throttle @ 13psi, as a result it will be rich and not running as much ign as it could, economy and part throttle acceleration would no doubt suffer?

Does that sound right? I have had sfa experience with map.

I find the physics behind the two systems interesting and the debate is an age old one. Although manufacturors indeed seem to be adopting MAF as the load sensor of choice the goal posts appear to be moving, largely (I suspect), due to the availability of cheap and fast computing power now available for ECUs.

MAF sensor ECUs don't use boost (manifold pressure) as a method of calculating air quantity. The "hot wire" AFM calculates air flow by measuring how much current is required to keep a wire heated above ambient temperature. The amount of current required is output to the ECU as a variable voltage signal. You are correct that even at WOT and constant manifold pressure, the engine load can change, and this is essentially due to changing revs.

To answer your question about MAP sensors, air quantity (n) is determined from the good old fashioned Ideal Gas Law (PV=nRT). Pressure (P) is measured by the MAP sensor, volume (V) is known from the engine displacement and rpm, R is a constant and temperature (T) is measured.

As SK points out, however, the manifold pressure of a multi throttle body engine (such as the GT-R) can potentially be turbulent and for this reason most MAP sensor ECUs (including the D-Jetro I assume?) also reference the TPS output to provide additional information to "smooth out" the calculated air use at partial throttle applications. It is interesting to note that the D-Jetro uses 2 pressure sensors in the manifold, presumably for the same reasoning that obtaining an average signal will smooth out the effect of manifold turbulence.

Which is best? I guess it doesn't really matter, but as long as people are willing to try and persist with different options everyone will benefit from the information.

[N I B]

The cars that went away from Wolf became shop cars that sell PFC so its natural they would change but the fastest was very drivable economical and still WAs fastest GTR 1/4 pass.

We are doing very well with them in WA again but if your shop dont sell them your gonna bag them thats why we service both options but im not loosing the near 600ks a tank our GTR gets with the prices of fuel these days.

I totaly agree with SK's thinking using MAF for multi throttlebodys tho Wolf and Djetro drive well with MAP the tuning is a little bit of a compromise.

[SRB]

i have the twin intake pipe i dont need it... came with my t51r kit....

im guessing u dont need it now? lol

[WetGTR]

The cars that went away from Wolf became shop cars that sell PFC so its natural they would change but the fastest was very drivable economical and still WAs fastest GTR 1/4 pass.

We are doing very well with them in WA again but if your shop dont sell them your gonna bag them thats why we service both options but im not loosing the near 600ks a tank our GTR gets with the prices of fuel these days.

I totaly agree with SK's thinking using MAF for multi throttlebodys tho Wolf and Djetro drive well with MAP the tuning is a little bit of a compromise.

N I B, could you give more details about the GTR that does close to 600k's a tank, like power levels, ECU and setup re: cams, injectors, compression.

I get an average 350km a tank with an Autronics ECU and 440awkw.

[rb30gtr]

Stuff it im buying some extractors and bolting webbers up to it......lol

[hungry6]

UMM OK, I bought into the country one of the very first D-Jetro and tried to get it running as smooth as the normal power FC. To be honest, it does get very close to the normal AFM power FC, but once thing is that, it rip through the fuel if your driving it hard, I have no explaintion as to why. I have now gone back to the normal power FC and stuck the D-jetro in the other skyline, which I selldome drive due to the way the car powers down.

[N I B]

My wifes GTR is 338rwhp stock turbos, large exhaust. Greddy cooler

Arias pistons but everything else stock using a Wolf plug and play with MAP sensor.Runs [email protected],A Few SAU members have witnessed this cars economy and the only way i can stop the knockers is ask Liz or Dan to make one of the SAUWA cruz's an economey trial like many other clubs do,Not so silly with our fuel prices.Ive been very fussy with the closed loop setup on this car and its been on the road for 2 1/2 years.

[B0BB0]

Just as another reference, my old gtr, had a totally stock motor with a mines ecu, and it made 345hp, and ran 11.8 which many ppl can vouch for. It was very fuel efficient.

Regards

P.i.p

16 + 17 + 34 = Fun times

Edited March 23, 2006 by B0BB0

[paulr33]

slight offtopic, but i wouldnt expect better or worse economy from a map sensor setup of an airflow meter setup. what i would expect to see is what cubes pointed it, more air is coming in but "ecu" is only told "same" amount of air is coming in via the guess method. the main things i would expect from a map sensor setup would be loss of tuning resolution (1 dimension via rpm only) and these is where it matters most.

map or afm i would still expect

max power to be fine

fuel economy to be fine

its the bits in the middle that matter to street tune (well mainly) is things such as cruising, light load, transition to boost areas, resolution and so on which the map setup will provide a 2nd best scenario to the airflow meter setup

[teejay]

Just as another reference, my old gtr, had a totally stock motor with a mines ecu, and it made 345hp, and ran 11.8 which many ppl can vouch for. It was very fuel efficient.

I remember watching it make 380 when lent on.

Thing was stupidly efficent for an 11 sec car. Thing would have to right right up there as quickest stock turbo / internalled GTR in WA if not Aus.

Dont count nos as its additional forced induction.

End of the day dude, you could make a lot worse a choice then De-Jetro. There popular for a reason.

Not only do they work well, but any import biased tuner should be able to do them right. Gives you massive flexibility!

Need a retune before a drag event and your guys not well or in jail, means anyone else competent enough can tune it. Getting a less reknowned ecu will mean options become limited, and makes things hard at times.

Its why im not a fan of roms. Leaves you stuck with one guy and one guy only. Likewise if an ecu has no tuner support, and you get stuck with a useless tuner, its going to limit the ecu's abilities.

Good luck with whatever you do.

Edited March 22, 2006 by [teejay]

[R32-GTS]

I have had a d-jetro in my gtr for almost a year now and been running 454rwkw's (630rwhp) for about 5 months now. I have nothing but good things to say about it compared to my old afm power fc. This was mostly due to the fact of having 2 afm's with a single turbo and them readng different voltages. Like sydneykid said splitting the wiring and using one afm is one way to get around it but i went d-jetro instead. It has excllent cold start , good fuel economy and runs very smooth. My 2 cents. Didn't take all that long to tune but that was because we had a base map to work with.

Edited March 22, 2006 by R32-GTS

[m&m]

Sydneykid im going to be running an atmo BOV on my S15 which is AFM equipped. Now this car is 100% for the street(minimal lag, smooth delivery, punchy), would it be best to go for normal FC or Jetro. My aim is 240-250RWKW(using a t518Z 8cm or APEXI p60). If i have normal FC and an atmo BOV, will my car stall or stutter, or is there a way of tuning it so it won't happen? Thanks heaps in advance.

I have an S15 with a T518Z 8cm turbo,making 250rwkw.I have a Power FC and a GFB adjustable BOV.The only reason I changed BOV was the stock one was leaking,it seems they cant handle 1.5bar.I have no stalling or stuttering issues.

This might help,start saving for a gearbox,as the stock boxes dont like 250rwkw with twin plates.You might just get away with a single,my Exedy hyper single lasted one run at Calder.I refused to go 5spd so it cost me $4800 for a PAR gearset.

Please dont think I am hard on my cars as my original clutch lasted 155,000kms,gearbox lasted 180,000kms and my dead stock bottom end now has 191,000kms.I wish my RB26 was this durable.

[GTRsean]

About the map sensor being subject to heat and vibration. Mine is mounted to the firewall and connected by vacuum line to engine. No worries if you do it that way...

Mine runs a HKS f-con with MAP sensor only buy the way. It needs more tuning for hot starts, coming onto boost (flat spot) and wide open throttle once at set boost. Other than that she runs okay with a D-Jetro (MAP SENSOR) set up.

[WetGTR]

I have had a d-jetro in my gtr for almost a year now and been running 454rwkw's (630rwhp) for about 5 months now. I have nothing but good things to say about it compared to my old afm power fc. This was mostly due to the fact of having 2 afm's with a single turbo and them readng different voltages. Like sydneykid said splitting the wiring and using one afm is one way to get around it but i went d-jetro instead. It has excllent cold start , good fuel economy and runs very smooth. My 2 cents. Didn't take all that long to tune but that was because we had a base map to work with.

Hi Simon,

How many km's do you get out of your tank? Not that I doubt anyone, I just want to know what they are capable of so I can aim for those figures. Good fuel economy is a must!! More money for mods instead of spending it on wasted fuel bill which pays for war on oil rich countries.

Didn't you have 468rwkw before? Did you lower the power levels?

Cams change the economy levels.

[rb30gtr]

I have had a d-jetro in my gtr for almost a year now and been running 454rwkw's (630rwhp) for about 5 months now. I have nothing but good things to say about it compared to my old afm power fc. This was mostly due to the fact of having 2 afm's with a single turbo and them readng different voltages. Like sydneykid said splitting the wiring and using one afm is one way to get around it but i went d-jetro instead. It has excllent cold start , good fuel economy and runs very smooth. My 2 cents. Didn't take all that long to tune but that was because we had a base map to work with.

Yeh thanks that is good to hear, I am still waiting on the de-jetro's arrival.

What was the base map you had already?

There is no chance I will get 454 rwks lol but would be nice. I am only aiming for around 300-330 hopefully.

I was running 225rwkws with standard turbos and just a chipped computer from japan, massive fuel gussler, drift day I got 120kms from a full tank..lol..

My car came with a switch in the boot to turn off awd and abs, very handy for fun.

The best thing about no afms is I will be running a 4inch inlet through the engine bay with a pod behind the 3 holes in the left of the bar, 9.5 by 6 inch filter for cold air.

[rev210]

BOBBO's new car does 600kms to a tank with the D-jetro, I remember Mike telling me how Danny proved it to him on a crusie. Mike since turfed his standard power FC and has the D-jetro now.