Someone Stole My Kw's !

[SLVR32GTR]

Hey guys,

I had my car put on the dyno yesterday at PITS and after a good 5hrs, the car didnt make anymore power than when i drove it in. There was some really weird things happening and i am racking my brains to think what the problem could be. First of all i will give you some specs of what the car is running:

Turbos and Exhaust

HKS GT-SS Turbos

Port matched and Flowed Manifolds

HKS Style Split Dump Pipes

Custom CES Front Pipes (3 ½inch Collector)

Catco Metal Cat

Trust 3 ½ inch cat back exhaust

Intake and Cooling

De-meshed standard AFM’s

PWR Intercooler

Oil Cooler and Remote Filter Kit

Fuel System

Sard 700cc Injectors

Bosch 044 fuel pump adapted in tank. (now direct wired)

Engine & Drivetrain

OS Giken Cam Gears

Gates Timing Belt

Standard internals

HKS GD Pro Twin Plate Clutch

Electronics

Apexi Power FC

Turbosmart EBoost2 Boost Controller.

The car made a maximum of 270awkw at 21psi of boost (which is what it made before bringing it in). To me that boost level seems way too high for the power level that i put out. According to the rb26 turbo upgrade thread, people running similar mods (with GT-SS's) are more around the 310kw mark at the same or lower boost levels.

Another thing that was odd, was that the afr's were differing greatly at the same load points. ie, we would do the low load tuning, get the afrs nicely around the 14.7 mark, come back later and they would be at either the 15.2 mark or 13.8. Both Matty and I were stumped and he said that he had never seen that before using a power fc.

The fuel pump also started making some weird noises later in the day, which we had put down to heat since the car had been running for so long. Matt said that the problems may be due to the charcoal canister purging unusually, and to try unplugging it and crosschecking with my tech edge to see if it fixes it.

So after that long explanation, my questions are:

Why does the car seem low on power for the amount of boost being pushed through it,

What could cause such fluctuations in the AFR's,

What could be done to gain the power that the car seems to be down on (ie would poncams make much of a difference?)

Thanks for reading guys!

Tony

PS. Top points to Matty for being such a good sport about it!! He really knows his stuff!

Dyno graph is from the original tune up, but looks pretty much the same as after we had finished.

Edited October 13, 2006 by SLVR32GTR

[SLVR32GTR]

I was thinking along the lines of:

Maybe there is a small leak in the intake piping, which would sort of explain irregular afr's, especially if the leak is affected by heat.

The air flow meters are maxxed out, but im not sure if this would actually affect power output as i dont think they would be a restriction.

Maybe fuel delivery is still an issue? Stock regulator is playing up or something?

One thing i forgot to mention also, is that before we direct wired the pump, it was running at 12.3volts at idle, but under boost, it was reducing down to 10.55volts.

More details can be found in the RB26 turbo upgrade thread here: http://www.skylinesaustralia.com/forums/in...93880&st=40

Edited October 13, 2006 by SLVR32GTR

[Beer Baron]

sounds to me like it's time to upgrade the AFMS so it can be tuned properly. that would account for your wayward AFRs I reckon as the engine is reading the same airflow after a certain point, but different things may be happening. also, it's possible your JASMA certified exhaust has quite restrictive mufflers.

[LatinR33]

yeah i agree with beer baron. Have to compliment you on your car and your mods always gets me tempted into investing in a R32 gtr but the chances of finding one in good nick are impossible.

[SLVR32GTR]

sounds to me like it's time to upgrade the AFMS so it can be tuned properly. that would account for your wayward AFRs I reckon as the engine is reading the same airflow after a certain point, but different things may be happening. also, it's possible your JASMA certified exhaust has quite restrictive mufflers.

Woops, it is a 3 1/2 inch Trust Cat back exhaust, changed in first post. It seems like a very open exhaust with a straight through muffler design.

I was thinking of upgrading to 2 x rb25 afms, but i was under the impression that this wont actually increase power as the air flow may be reading the same points, but it is not actually restricting the flow. We had it set up for the best AFR's on top boost, and it resulted in slightly richer runs in the lower boost settings (as they used the same load points.)

[SLVR32GTR]

yeah i agree with beer baron. Have to compliment you on your car and your mods always gets me tempted into investing in a R32 gtr but the chances of finding one in good nick are impossible.

Thanks LatinR33, it took a good 6 months to find the GTR i bought, as there was a lot of junk out there. It had a genuine 67,000k's on it when i got it, as can be determined by the condition of the engine and interior parts that we examined carefully.

All of the fitting of the performance parts was carried out by myself with the help of some mechanic mates and the use of a hoist. Although it was a b*tch to work on in the cramped engine bay, i really enjoyed the hands on and knowing that i had done it myself.

Cheers

Tony

[Beer Baron]

Hey Tony,

I wouldn't bother with the RB25 AFMS. go straight for a set of Nismo ones, or if you must VG30s. I personally dont think the physical size is much (any?) of a restriction. clearly in your case though, the sensor is out of range and needs to be replaced.

[SLVR32GTR]

Hey Beer Baron,

So are the VG30 afm's the same diameter as the RB26 items? That would be handy as i wasnt too keen on changing the original pipework.

I understand that this would help to improve the AFR's, but do you think that this would find any of the power that seems to be missing??

Also, before taking it to matty, i went for a cruise with some mate, and while we were sitting there idling, the car seemed to be running super rich and fouled the plugs a bit. As we drove off the car coughed and spluttered for about 1 minute or so afterwards. Would this imply that the plugs are no longer working at optimum?? They are PFR7B's and are only about 3 months old at most.

Cheers

Tony

[Beer Baron]

the VG30 AFMS (comonly called Z32s) are larger than stock, so new pipework, or adapters is needed. The nismo ones are basically the sensor from a VG30 AFM put in the body of an RB26 AFM so they are direct bolt on.

the plugs should be fine. it may be worth taking them out and giving them a carefull clean. it sounds like the tuning may be the problem with fouling at idle.

[SLVR32GTR]

ahh ok Z32's gotcha. The fouling happened before the retune, i was just thinking maybe the spark wasnt as strong, resulting in less power due to less efficient burning of the fuel or something.

[SLVR32GTR]

After thinking about it at lunch, the only thing i could come up with, with respect to the low power, is that the head isnt breathing enough. It couldnt be an air or fuel issue as the engine is seeing 21psi and there is enough fuel to balance the AFR's, (Obviously you need more fuel and the associated air to make more power) so i think maybe the cam gear settings arent at optimum. I never checked them after i got it tuned the first time, but that would explain the drop off of power at the top end.

I think the missing power may just be the result of un-tuned cam gears or due to the lack of after market cams. Would this be the culprite??

Cheers

Tony

[SLVR32GTR]

Hey guys,

I will be away for work until Thursday, but i would appreciate if you could all leave your comments/ideas on why my gtr seems down on power!

Thanks

Tony

[MBS206]

Something just isn't breathing...

Are the cams dialled in properly (In the correct position) they may be opening and closing too early or late.

Head might not be flowing adequately either.

Turbo may be out of efficiency. Did you try winding the turbo down to see how much lower you can get boost without loosing much power?

[fEkuaR]

Im sorry its true i stole your kw's *hands back* =(

[GeeTR]

I’m under the impression a RB26 head will flow well over 400rwkw.. so beh.

I think your confusing the difference between AFM's being a restriction to physical air flow and them running out of signal output resolution. Nismos units will just bolt up to your stock piping and plugs.

Your loss of kw's is a bugger, could be a lota things, fouled plugs, lack of good spark, incorrect exhaust cam settings, fuel pressure fluctuations, ex GF, jealous work office colleague - write a list, and think of scenario to fault find each problem, work your way down

Good luck man

- mikey

[Spook's_Skyline]

did you get it dynoed at PITS first?

mattys dyno reads WAY lower than other dynos

my 195rwkw, read 160 at PITS

[cameron]

did you get it dynoed at PITS first?

mattys dyno reads WAY lower than other dynos

my 195rwkw, read 160 at PITS

Matty did tell me this aswel. He said about 10% due to the old version of DD software.

[The Dan]

Matty did tell me this aswel. He said about 10% due to the old version of DD software.

Apparently he just upgraded it only a few weeks back

[The Dan]

I’m under the impression a RB26 head will flow well over 400rwkw.. so beh.

I think your confusing the difference between AFM's being a restriction to physical air flow and them running out of signal output resolution. Nismos units will just bolt up to your stock piping and plugs.

Your loss of kw's is a bugger, could be a lota things, fouled plugs, lack of good spark, incorrect exhaust cam settings, fuel pressure fluctuations, ex GF, jealous work office colleague - write a list, and think of scenario to fault find each problem, work your way down

Good luck man

- mikey

Kier Wilson (I think it's him) runs his 8 second drag car on stock RB26 head. This would indicate a flow capability of much more.

[The Dan]

Hey guys,

I will be away for work until Thursday, but i would appreciate if you could all leave your comments/ideas on why my gtr seems down on power!

Thanks

Tony

Try re-meshing the AFM's. Why you would remove the mesh is totally beyond comprehension. The mesh is designed to improve AFM readings to be more accurate.