Valve Springs

[Pretzel]

Just wondering why replacement valve springs (Inlet and Exhaust) are suggested with the APS Phase III.

My understanding on putting in better valve springs in performance engines is that this then allows more revs without Piston meeting Valve in a dark alley at very high speeds ! where neither come out quite the same, and cost lots of dollars to rectify !

Now assuming my understanding is correct, and as the Phase III does not seem to be revving any harder than stock (According to the Dyno Graph on the web page) what is the reason for putting better (I guess heavier) valve springs in the motor ? Would the valve springs supplied in the motor already not be suitable for anything we can throw at them (Providing of course we stay at or below the factory imposed rev limit).

What would the difference be between a Phase III with stock springs, and one with heavier ones (Heavier ones would put a little bit more load on the cam and followers, which would take a whisker more force to open, would that not affect the engine's output slightly ?)

Just want to get all my info right before approaching the Minister for War about funding an upgrade!

[Adam]

Not sure what the connection with the phase 3 kit is but I know there's been an issue with the valve springs in stock form on some T's, so modifying doesn't help the sisuation any. This problem has happened to a few members here so I'm sure they'll post what the specific problem with the springs are.

[TURBO4LT]

I think its probably due to the issues some people have had with weak springs. Also it could be related to the substancial increase in boost pressure of the Phase 3 kit, which will increase pressures on the valves. Just guessing

[Guest Ahiles]

Hi Guys

It maybe a good idea to change the valve springs even with a Phase II kit just to be on the safe side.

AM

[CnC]

It is due to the extra torque loading on the valve springs in the Phase III kit as a result of the additional boost pressure. As Nizpro, APS and others have mentioned the valve springs are marginal at best and have been known to let go in standard motors, let alone boosted motors.

The valve springs end up 'sticking' and it results in the car sounding like its dropped a cylinder or two. The problem usually goes away after a few minutes of driving however.

[OwnaXR6T]

what problem are the valves springs causing?

can they cause pinging under load?

[hypnodoc]

what problem are the valves springs causing?

can they cause pinging under load?

Hi Owna.

I got told that the first few batches of valve springs were too weak, and that they could be replaced with GT springs. Ford apparently fixed the problem in the first 6 months of production. Pinging can only be caused by running too lean, e.g too much boost, too little fuel. Or low octane rated fuel. PINGING DESTROYS ENGINES.

[OwnaXR6T]

what problem are the valves springs causing?

can they cause pinging under load?

Hi Owna.

I got told that the first few batches of valve springs were too weak, and that they could be replaced with GT springs. Ford apparently fixed the problem in the first 6 months of production. Pinging can only be caused by running too lean, e.g too much boost, too little fuel. Or low octane rated fuel. PINGING DESTROYS ENGINES.

yeah I thought that was the case, a car would have to ping very hard and for a long time to destroy a donk wouldnt u think?

I should consider valve springs though I have a nov build.

so if a valve spring is weak what can happen?

[aps]

The valve spring issue is related to the amount of exhaust back pressure at the exhaust valve the higher the turbo pressure in the inlet manifold the higher the back pressure will be at the exhaust valve hence the valve spring cant close the valve quickly and in high boost conditions the valve lash adjustor pumps up and causes an engine miss under high load. THE miss will come good after the engine idles for approx 30 to45 seconds, and the problem is directly related to total exhaust back pressure,which is why a zero or very low back pressure exhaust system should be considered mandatory equipment for 300 plus Kw applications.I guess by now you guys have a real insight as to why APS went to great lengths when designing a combination 3.5''/ twin 2.5'' zero restriction exhaust, with the 3.5'' high flow cat which is the only cat that will deliver low back pressure at 500 plus horse power on a 4 litre turbo engine. No doubt we will all see and hear plenty on this issue over the coming months as more owners try to reach higher power levels.

[ms700]

Do APS use the Boss 290 valve springs? I hear they are much stronger and a direct changeover?