Jump to content
SAU Community

Recommended Posts

The rb20 N/A cams trade a little top end mid range. The N/A cams are essentially 'smaller'.

The best upgrade for a stock engine is no upgrade. Spend the $$ on a nice turbo and the rest of the supporting mods then throw decent cams in it.

if you have an OEM turbo engine, it is best to keep your OEM cams, or replace them with cams designed for your engine.

NA cams that are more aggressive, will have valve-overlap, meaning that at one point in their cycle the intake valve is open at the same time as the exhaust valve. so if you use this in a turbo engine, all your boost will go in through the intake valve, and out the exhaust valve before the spark even fires.

if youre boosting a mild NA engine (meaning that the engine isnt a very high performing NA engine, like less than 100hp/L of displacement), then you should usually keep the stock NA cam for low boost.

one good example is my VW 2.0L 8v engine (makes 110hp). there is no valve overlap on the stock cam, it is great for boosting. but my friend's Honda B18C5 has a small amount of overlap, so he changed the cams before running too much boost.

impreziv,

The rb20det cams run less duration and lift, BUT they do run more overlap, around 8degree's from memory.

I'm running the standard N/A cams in my rb25 head, the inlet is the same as the turbo cam however the exh. cam runs slightly less duration and lift.

The 25 na cams also run an overlap of around 8degree's where as the turbo's run 0 degree's overlap.

But yes, I experience a little funny flat spot at low rpm where no matter how much fuel I push in it still reads lean. Maybe the overlap at that rpm is such that the charge is blown straight out the exhaust.

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

    • Next, remove the upper and lower radiator hoses, both are held with a spring clamp. While you are under there, tackle the Auto Trans cooler lines.  Again both are held on with spring clamps, and as mentioned above you should cap them on the radiator side with an 8mm cap, and on the car side loop them with a length of 8mm pipe - this will stop you losing a dangerous amount of AT fluid during the rest of the job If you've been meaning to add a sender for AT trans temp, this is a great time to do it; put a sender fitting into the passenger side line as that is the inlet to the cooler/radiator.
    • Next you need to remove the intake duct (as with pretty much every job on these cars), it is a series of clips you gently remove with a flat bladed screwdriver. They do get brittle with time and can break, and I have not found a decent quality aftermarket one that fits (they are all too soft or flimsy and don't last either) but the nissan ones are a couple of bucks each (ouch).  Once the clips are off (either 8 or 10, I didn't check) you lift the intake duct out and will see the reservoirs Undo the line into the radiator side cap (some bent needle nosed piers are awesome for spring clamps) and then remove the 4x 10m nuts that hold both in place.  I didn't get these pics, but remove the line under the radiator reservoir (spring clamp again) then remove that reservoir. Then you can get at the intake reservoir, same thing, spring clamp underneath then remove it. BTW This is a great time to put in a larger (+70%) combined reservoir that AMS makes..... https://www.amsperformance.com/product/q50-q60-red-alpha-coolant-expansion-tank/ They also make an Infiniti branded and part# version if that is your thing
    • To drain the Intake Heat Exchanger, there is a crappy drain plug in front of the driver's side front tyre: You should use the largest headed phillips screwdriver you had, and in my case I needed vice grips on the hose above as the plug was tight (tighter than it needed to be, since it has an o-ring seal).  After you have a tray down and open the drain, open the intake heat exchanger reservoir cap (drivers side one) and you should get a couple of litres of coolant To get to the radiator, you need to remove the plastic engine undertray. It is held on with a series of 10mm headed bolts and some clips. For the radiator, there is another type of crappy drain (kind of like a plastic banjo bolt) and you should attach a length of hose to direct the stream of coolant per this pic (otherwise the coolant hits the rad support and goes everywhere). The drain is on the rear of the radiator on the driver's side and a bit hard to find. Put a big tray or bucket down (5l won't be enough) and slowly unscrew the fitting by hand. You only want to remove it far enough for coolant to flow, it you unscrew it right out the whole fitting and direction pipe will come off and you will get a coolant bath (yum!). Undo the radiator reservoir cap and it should empty about 8l
    • So, this shouldn't be such a mission, but there were a few tricks so I thought I'd post up a DIY for it. This was on a Q50 Red Sport but I doubt any other V37 model is very different (maybe just less steps for the intake heat exchanger hoses) I pulled the radiator out to flush it because the car was running hot at the track, but obviously the same steps apply for changing a radiator for any reason including an upgrade. If you are removing the radiator, you of course need to drain and refill, so have 5+ litres of blue coolant ready. You also need to drain the intake heat exchanger to remove the radiator so you will need a couple of litres for that as well. You will also need something to deal with the auto transmission lines, I used 2x 8mm rubber caps on the radiator side, and a short length of 8mm pipe on the car side.....unless you can block these lines quickly you will loose AT fluid and it may be enough to hurt the transmission if you don't refill it. 2 other tools that really help dealing with coolant lines and spring clamps are Bent Needle Nose pliers Hose pliers Between them they will reduce the frustration (and injury) potential by about 1000% Other than that....lets go... "First, jack up your car". Yes really, and put it safely on stands. If you are not confident doing that you need to give this job to a mechanic
    • If the forester is anything like our old 2007 GTB Liberty, I could near on run ling Long's and "rate them", as no matter what, it just hung to the road, even when abusing it in a hard launch in the wet, or throwing it at corners.
×
×
  • Create New...