JMM dyno results
As promised, I have some before and after dyno results with various modifications to a 97 I6 XH 5spd ute (128000k).
The first dyno run I made was a few months ago and unfortunately I'd already fitted an exhaust system, so I don't know how much power it had when completely standard.
Anyway, it's peak power was 122kw at that point.
From some other reports I've seen, the standard car produced 118kw.
4kw from an exhaust sounds feasible and although it didn't feel heaps more powerful, it was a little more willing to rev.
The next modification was a the fitment of the broadband manifold, this made quite a difference to the bottom end performance, but made no noticeable difference up top.
The dyno proved this assumption showing around 15kw increase from around 2800rpm to 3600rpm. The top end actually dropped very slightly down to around 119kw.
Step 3 came the JMM extractors, plugs and leads.
The engine felt very lively after these went on, revving out to redline much easier and not feeling so restricted. Power seemed to be improved right across the range.
Again the dyno proved this with a 3-5kw increase from the moment the throttle was opened. Peak power was back up to around 123kw.
Step 4 came the JMM DEV3HL cam, valve springs and vernier gear.
Wow, this made a huge difference, the engine now loves to rev all the way to the cut-out of 5700rpm.
Power seems much the same at low revs, though a little stronger at the manifold changeover point (3800rpm), but above 4500rpm is where it really takes off.
The dyno again, re-inforced what I felt, with an improvement of around 7kw between 3500-4200rpm (no improvement below this though), and a 15kw improvement above 4500rpm to peak at 138kw.
An excellent result I think. JMM claim 150kw from this package which has now been followed to the letter, though taking into account dyno differences and engine age (128000k), I can comfortably say that the DEV3 HL package lives up to it's claims.
I did speak to Jim from JMM about the results, and he suggested that I could advance the ignition timing a little further and possibly get a little more out of it. I haven't had a chance to do this as yet, and I don't really want to spend another $40 to play around with ignition timing, but I will report back with seat of the pants feel, if it appears to make any difference.