Bollox

[F2 Stu]

Got a bit of a dilemma, well cant decide what to do.

Basically its two weeks till the forthcoming weekend at mallory park and some of you may be aware of some woes regarding a Piper camshaft I bought last year.

The plan was to fit the camshaft this weekend & get the manifold blow sorted ready for the next weekend (21st)so that stealth racing could work their magic on their RR and tune the car to the camshaft ready for the fun @ Mallory

Trouble is my plans have been shafted (no pun intended) as Piper for whatever reason have not done what they said they would do and have a shaft ready, having me provided what they wanted in their timescale.

As my car was running lean at the top @ recent SCN sesh the car was booked in to adress the lean fueling and complet the instalation of the PBV, would of been even nicer to have the cam in there and have the valve tuned to it.

Do I;

a) leave the camshaft out, just get the pbv completed and tuned fit cam later date after mallory & then get them to retune the car after its fitted which means a 2nd visit/session

b) Cancel the rr tuning (which makes me look like a timewaster) this side of mallory, just fit the cam and make the lean fueling worse?

c) get the cam installed by someone else or by stealth & just swallow the cost, saves a second return to stealth which inst exactly local.

£££ isnt a stumbling block, I'm just reluctant to part with it when I can do the job myself easily, the stumbling block is time which I dont have alot of due to work commitments.

Help:(

[Feel]

If someone's mucking you about - don't trust them to stop mucking you about.

If you cancel everything, and then don't get the cam sorted, you'll be more gutted than having to sort it twice, if you get my drift.

[F2 Stu]

Thats what I was thinking, the RR tuning will take about 2hrs the cam will also take 2hrs (my estimate) If I have it tuned then fit the cam my self afterwoods, it will cost another 2hrs+ travel for the retune.

I must also add that stealth has nothing to do with woes of the cam itself;)

[max_torque]

The problem you're gonna get with the PBV is that i will add extra fuel all the time, so the "closed loop" fuelling is gonna adapt to remove this extra fuel at part load conditions, hence when you cone to actually get wide open throttle there will be a big "lean" trim saved into the fuel adaptions in the ecu, which will take even more fuel pressure to remove. Also as the system will take a few miles in closed loop to adapt you may find that you perfectly optimised dyno fuel pressure slowly becomes too lean again. This can really only be sloved by a proper remap (which you want to reoptimise your ignition timing anyway to maximise the cams advantage).

As a quick and simple bodge you can try to add more resistance into the engine coolant temp sensor, but engineer a "full throttle switch" so it only adds the extra resistance when you are actually wide open, so under part loads and closed loop the system will run and adapt normally. only adding extra fuel / ignition when at WOT (when the system will not be adapting)

Your coolant temp sensor will either be a 0 to 5kohm or 0 to 3kohm sensor, i suggest fitting a 5 kohm variable pot in series with the coolant temp sensor, but use a "normally closed" micro switch in parrallel with the pot. Arrange for the switch to click open at WOT (i used a small ally plate bolted to the throttle body mounting the switch, and another little ally tab on the throttle cable wheel so that as you got to WOT the little tab clicked the switch in) which will in effect then add the extra resistance into the system. You can assume that if you set the 5k pot to add the full 5k then it would be similar to adding fuel for an engine at -30ish degC, and with the pot at about 1kohm would be similar to an engine at 30degC.

when at WOT on the rollers simply adjust the pot until you have added enough fuel, but beware a cold engine will also have more advanced ignition, which due to the extra cylinder filling of your cam at high rpm maybe the oposite of where the new ignition timing should be. (keep an ear out for any DET!)

[WeeJase]

if you explain why you have to cancel(not your fault is it?)most people wouldn't regard you as a timewaster.get the job done properly in one hit mate,rather look a timewaster then a"this guys been here twice now,what a plonker";)