Jump to content
SAU Community

Recommended Posts

Nah, power noses over at about 6800.

From what I have seen and experienced the standard cams fall over at approx. 6,000rpm.

Although a lot of cars feel as though they are still pulling away strongly after 6k, mine included, a dyno graph will show power on the decline after that mark.

A good example is Troys RB20 who from memory makes peak power between 6-6.2krpm. But shifts far north of 7,000rpm on occasions.

Surely a much larger turbo would change the power band a bit?

Nope, only cam timing does this and duration and lift. I fitted a GT30 on my car and peak power is the same as it was when I had the standard t3 which means my car is acutually a lot slower down low now because now the cam timing events are still the same ie too early for the GT30.

Turbo provides airflow.

Cam timing determines when this airflow is most efficient.

If you fit big turbo, it will want will not change when the cams open at a certain rpm and thus you will still have peak power at the same rpm. This may not be the case however if your orginal turbo was really shit and couldnt provide enough air through the cams efficiency range.

Larger exhaust housings create less back pressure that improves top end VE. This in affect will help extend where peak power is made.

A good example is the rb20 turbo on the rb30det. lol.

Peak power is made by 4400rpm then goes flat and falls off rapidly after ~4900rpm.

The larger exhaust housings raise peak power to around 5800-6000rpm.

Back pressure = reversion.

The stock log manifold = back pressure + unequal reversion.

Which is why an equal length exhaust manifold is best for peak rpm power.

So realistically if you want to keep the stock log manifold keep the cam specs mild.

If you really want to extend your peak power you must not only do cams but also look at your exhaust manifold, ensure the turbo exhaust housing can handle the higher airflow at highrpm.

Possibly why Roy's power looks so awesome.

Nicely sized exhaust a/r equiv to .7 something from memory + a nice exhaust manifold. All he needs now is a nice set of cams. :P

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

    • Yeah well per the video it took 15s for the stock unit to start up....even if I give it a few seconds discount for starting that is at least 12 sec before you get a reverse camera if you are trying to leave a park.  The android unit is way faster, but 2016 for the stock unit is a long time ago in consumer electronics
    • Yea that’s why I said ima test them with multimeter and see the reads.
    • Only at idle. Isn’t a problem when rev it seems.
    • @Haggerty This seems silly to ask, but are you confident in your ability to tune the Haltech?  
    • Next on the to-do list was an oil and filter change. Nothing exciting to add here except the oil filter is in a really stupid place (facing the engine mount/subframe/steering rack). GReddy do a relocation kit which puts it towards the gearbox, I would have preferred towards the front but there's obviously a lot more stuff there. Something I'll have to look at for the next service perhaps. First time using Valvoline oil, although I can't see it being any different to most other brands Nice... The oil filter location... At least the subframe wont rust any time soon I picked up a genuine fuel filter, this is part of the fuel pump assembly inside the fuel tank. Access can be found underneath the rear seat, you'll see this triangular cover Remove the 3x plastic 10mm nuts and lift the cover up, pushing the rubber grommet through The yellow fuel line clips push out in opposite directions, remove these completely. The two moulded fuel lines can now pull upwards to disconnect, along with the wire electrical plug. There's 8x 8mm bolts that secure the black retaining ring. The fuel pump assembly is now ready to lift out. Be mindful of the fuel hose on the side, the hose clamp on mine was catching the hose preventing it from lifting up The fuel pump/filter has an upper and lower section held on by 4 pressure clips. These did take a little bit of force, it sounded like the plastic tabs were going to break but they didn't (don't worry!) The lower section helps mount the fuel pump, there's a circular rubber gasket/grommet/seal thing on the bottom where the sock is. Undo the hose clip on the short fuel hose on the side to disconnect it from the 3 way distribution pipe to be able to lift the upper half away. Don't forget to unplug the fuel pump too! There's a few rubber O rings that will need transferring to the new filter housing, I show these in the video at the bottom of this write up. Reassembly is the reverse Here's a photo of the new filter installed, you'll be able to see where the tabs are more clearing against the yellow OEM plastic Once the assembly is re-installed, I turned the engine over a few times to help build up fuel pressure. I did panic when the car stopped turning over but I could hear the fuel pump making a noise. It eventually started and has been fine since. Found my 'lucky' coin underneath the rear seat too The Youtube video can be seen here: https://www.youtube.com/watch?v=uLJ65pmQt44&t=6s
×
×
  • Create New...