i have an eb v8 that i bought (from ebv8 of all people) already modified which can be a bit risky but in this case its all been o.k. up until now. as i am reasonably new to v8's i am on a constant learning curve. the car has a crow cam, supposedly 2 grinds on from the au 220 cam. i have no part no or stage no. when i bought it i got it tuned and returned a healthy 158.4rwkw. proof enough that along with the aftermarket ecu there is a reasonable cam in there. the question i have is with the rocker gear. would it still be std? i am yet to lift the rocker covers but even if i did i wouldn't know by looking if anything was different to stock.

the reason i'm asking is recently the car has felt a bit tardy and after another visit to my tuner, i've discovered that its now only producing a pathetic 136rwkw. dropped the exhaust in front of the cats thinking they might be the culprit but all looks good in there. nicely stuck around edges, no melting look, nice and clean etc so that rules that out. the tuner said he could hear what sounded like a dry rocker (i couldn't detect anything) but didn't think that would create such a drop in power.

afr's were all good. it was a hot day but not hot enough to rob 22kw.

if i do lift the lids and discover its all std, i've read on here about others changing to a diff ratio for a small gain in power. is this something i can do? if so is it a do it yourself job? i am reasonably well aquainted with a wide range of tools .

thanks in advance for any help.

Lowering the diff ratio does not make your motor develop any more power, but it will increase the accelerative ability of the car. The auto EB v8's had a 3.23 diff in them (if memory serves me correctly). XR6 diffs had 3.45:1 gears in them and will result in slightly quicker acceleration. Bare in mind that on highway cycle, it will result in reduced fuel economy, as you will be carrying more revs at speed.

I think if you had a dry lifter, or a problem that was robbing the motor of 22rwkw, you would be able to hear the issue wuite easily, cos that sounds like a lot. (Are you sure the dyno was in the same mode and was it the same dyno? as figures from one to another can vary substantially).

I wouldn't have thought a dry rocker (that you can't hear would rob the engine of 22kw. I'd have a look at simple things like plugs, leads etc before I worried about the rockers.

yes the tuner and myself both thought the same. the dry rocker sound is not robbing any power but could create a problem in the future if not looked at. if left unattended and its bad enough could eat into a cam lobe adn i don't want that. everything else checks out fine. no misses and afr's are all spot on. tuner is a gun with microtech, hence the reason i go there (boostworx for all you s.a. guys)

philladis - not sure where your comments regarding diff ratio are coming from. just so you know i have 3.9 gears (minispooled as well) so i know all about pro's and con's.

Apparently not........ I'm pretty sure you asked the question, so I answered it.

I don't know where you are getting your information re diff ratios making your engine more powerful...... cos they umm don't!

Last edited by philaddis on Thu Jan 18, 2007 7:02 pm, edited 1 time in total.

He means "diff"erent ratio roller rockers

Roger........

My bad!

You can get 1.72 ratio rockers to replace the standard 1.6, but this is very risky and will more than likely end with valves smashing into pistons if you don't know what cam is in it.

thanks steady.

They are roller cam followers so there's no chance of dry lifter.. You could check if there's oil comeng out of pushrods...I'd be checkng MAF , ignition..

mafless...

the problem mentioned about the rocker is not likely to be causing the power drop, just something that may need to be looked at in the future. i can't hear anything, but he claimed to be able to detect a slight squeak/metal on metal type noise which he said could be a dry rocker. said some crap could be built up in with one of the pushrods not allowing the oil up.

plugs are only a few months old, leads are maybe 6-12 months tops. it still makes a nice power smooth power curve, just down on previous run.

i've had it on his dyno twice before and made 158.4 and 158.1. these runs were a month apart so dyno seems consistent enough. i doubt he would've entered in a wrong variable as he just loads up the rego number and brings up all the info of last runs.

its prolly not down a full 22rwkw. it was a very hot day so it may only be down 15 or so. popped the lid on the airbox for a couple of runs and made no difference. added 6 or so degrees of timing, no difference, took some timing out - no difference. just didn't seem to respond to anything. afr's were fine. as straight a line as you could have.

i wonder if it could be a trans issue. i'm sure that would've shown up though if the torque converter was slipping or something.

cars eh, gotta love em. i was very close to putting an ad in the paper yesterday arvo. always seems to be something going on.