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Dyno Result

abcent

By abcent,
in Engines & Forced Induction

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CEF11E Veteran

CEF11E

Posted
Posted

I have retarded the timing on my RB20 by exhaust cam by 4deg running 19psi with a slide hiflow and have noticed the difference right away.

Firstly the A/F ratio went from a flat 12:1 to a bell curve starting at 12:1 at 3400 and leaning out to 12.6:1 at 5000 and then settling back down to 12:1 at 7000. I used a tech edge with data logging to measure this.

I have reset the base timing to 15deg as it actually dropped 3 deg after retarding the cam timing.

The car is now coming on boost slightly quicker and hits full bost around 200-400 rpm quicker depending on the gear and the midrange FEELS more responsive. peak power feels the same but it gets there quicker so the whole package feels faster.

I added fuel to compensate and bring the AFR's back to a safer level and keep it to 12:1 as close as possible.

I have not touched the timing map as there is no detection of knock. I use a modified condenser microphone connected to a laptop recording in real time and can be referenced to the rpm scale of datascan.

so all in all looks like quite a decent gain. seat of the pants tells me there is no more power just power earlier in the rev range and let's face it all RB20's need earlier power delivery.

CEF11E Veteran

CEF11E

Posted
Posted

without tune yes there was more response but it was leaning out. so i have already added fuel and there is more response but no more peak power.

I am only speculating as i have not had it on a dyno. but it comes on boost faster yes :no:

CEF11E Veteran

CEF11E

Posted
Posted

there would still be gains to be had even form a stock turbo. the amount of overlap Nissan designed was a compromise between response and power and emissions. with the amount of overlap they run stock you get a longer cleaner burn but less power.

so you may gain some midrange power with a stock turbo but there would be cheaper ways of getting the same performance increase from a relatively standard car.

You can buy one of the arospeed cam gears for $70 but a mechanic would charge you $200 to install it and you will need to pay for atleast an hour of dyno time to get a confirmed result. so it would end up costing you almost $400.

For that amount you could buy and install

front+dump pipe, FMIC, SAFC or a boost controller. all of these will give you good gains. the cam gear is really something you would do after the more common mods.

very worth while if you have already done the basics.

After going for a nice long drive lastnight i can say boost comes on just that bit earlier and makes a big difference in how the car behaves.

Tangles Grand Master

Tangles

Posted
Posted

sweeeeet.

getting my aerospeed exhaust cam gear installed, exhaust manifold studs replaced, gaskets replaced, and dyno tune with the FPR, Z32 afm, SITC, SAFCii and the Slide highflow. Got the fuel pump, the intake and exhaust is full sorted. Should be good ! :D

under $700 too

BAMR33 Mentor

BAMR33

Posted
Posted
is it worthwhile adding adj camgears to an engine with stock turbo (to tweak power delivery rather than for outright power gains)?

or should you only consider this if you've upgraded your turbo too?

In previous threads some people have had no gains by retarding the ex cam on a fairly stock motor. The problem with a stock turbo is the small turbine wheel, which causes backpressure. This back pressure causes the spent gases to re-enter the combustion chamber if over lap is too great.

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