Wreck to Race.

[Peter Jones]

Just back from the Dyno - 81kW at the front wheels!

• Power up to 81KW
• Jetting upped as it was leaning out up 5K 6K 7K
• Mains increased to 159 (Was 145)
• Was pinging - compression is up heaps.
• Timing set for 2° static 24° total.
• Cam Timing best left at 0°

Very different car to drive now.
Here's the old and new plots side by side.
The RPM scale is a bit more compressed on the newer plot as this time round as the diff ratio is lower.
Bigger valves, bigger ports, bigger cam, +2mm on the Venturis, Higher compression.


Here's a hi- res version should you want more detail.
http://i221.photobucket.com/albums/d...e/P1340036.jpg

Need to see if I can get cold air to the carbs, there's a kW to be had. The 81 pass was with the bonnet open, the 80 with it closed, both ways the inlet temp was pretty high.

Gear linkages need a sorting out too, The motor might have shifted a fraction and selecting 1 & 2 is a bit tricky at the moment. I missed a shift on the way home and something made a worrying noise. Tomorrows job is to figure out what the noise was. After an inital inspection I don't think it's engine or box related, sounded more like a something wrapping around a driveshaft, might even have been road debris.

It goes like a cut cat now! Very happy with the result, I would have killed it for sure if it weren't for the Dyno, it was lean and pinging at high RPM before the tune.

Compression is way up, Dyno people think I've hit about 11.5:1 which is what I was aiming for. Made for a very narrow tuning window for them though. A couple of degrees either side on the cam or ignition timing and the power drops off or it starts pinging. That's why only 24° total advance.

Sounds like an F2 car now, probably way too loud to drive on the street much anymore.

Next outing is Phillip Island Sprints on Sunday the 14th of Feb. Supp regs are up on the PIARC site and there's driver familiarisation running on the Saturday if anyone wants to get some practice in.

Pete

[Jarred]

Can't wait to hear it now Pete! on full song at 7000rpm! glorious!

[Geoffrey Hale]

Sounds good Pete. I wish I had that horsepower in the rally car. You know it goes faster if you think of it in horsepower. That's real power not this kilowatt rubbish So that's about 105 BHP @ the wheels and what do you think, say 125 / 130 BHP @ the flywheel ? Good stuff. On 11:1 comp ratio I wonder if you might even get a bit more if you used a higher octain fuel on track days. Maybe add octain booster ?

Cheers ........ Geoff

[Peter Jones]

Just doing my post checks now.

Pulled all the plugs and the chambers look OK.

Pulled the rocker cover off and all all looks good.

Inspection down the bellhousing looks OK.

Compression test reads at 150,150,150 and 40.

I think I've got a problem!

Hopefully just a valve spring.

That sort of changes my plans for today.

Pete

[Geoffrey Hale]

OH DEAR ........ Geoff

[Peter Jones]

Oh Dear indeed.

Valve train is OK.Springs are all OK and the valves look OK too. I dropped them down enough so I could inspect them through the plug hole.

Compression numbers might have been a red herring. I'll retest with no cam across all 4 in a moment.

Motor stated and ran fine but there's a mechanical grinding noise at low RPM.

Time to look elsewhere I think. Might have to drop the box and take a look at the clutch next.

Pete

[GoLfMan]

bugger Pete,

REALLY looking forward to hearing this in the flesh, would sound phenomenal!

hope everything works out ok!

[Peter Jones]

Retested comps with no cam, numbers are better on #4 but not ideal.

(Not a great test by the way, I'd do a leakdown test if I had the kit.)

I'm puting the top end back together now, wondering to drop the sump or pull the box first.

I'll start it up again and see if I can figure out the issue.

Pete

[beeza]

Just back from the Dyno - 81kW at the front wheels!



Pete

Wow, thats better, now thats a more typical power curve. I'd be quite happy with that. Must feel quite good especailly between 4-5.5k. The power curve is quite steep there. Plus it pulls right up till about 6700, must be fun in that light car.
I love the whole 8V approach, as you already know. Keep it up, and good luck finding your problem.

[Geoffrey Hale]

Hi Pete . I am thinking the low comp and the noise are related. Sort of makes me think piston area. Oh well if everything looks good in the bottom end may have to lift the head I guess.