V6 piston choices?

[Holden202T]

have you thought about getting flat tops and have a bit milled off the top of them ? shouldn't take much to get the comp down where you need it ?

or alternatively flat tops and mill a smaller dish into them than the normal pistons have tailored to your needs ?

[immortality]

I dont want too big, most of my driving is cruise @ 1800-2100rpm but just want more punch from low rpm to redline. certainly dont want to rev past 5500, 6k max.

so cam will be mild but dont know yet. I want to get this simulation program and run a few of the off the shelf cams to see what does what and then play with custom cams to suit the engine.

basically im going to build the block 1st and then cam last, tailored to the rest of the engine.

If you want to maintain the same sort of usable rpm range as a standard engine than you will end up with a fairly small cam.

More rpm doesn't necessarily mean more fuel. I put some 3.45 gears in my old VN and it didn't use any more fuel. Bigger cams are also more efficient at higher rpm. IF you try and drive a decent cam at low rpm the engine is just going to struggle.

I think the MACE stage 2 Comp cams grind is fairly reasonable. Goes reasonably well on a stock engine, would go much better with a decent bump in the CR ratio. IF that is to much RPM that sim up the stage 1 grind, it's more of a low rpm torque cam, perfect for towing etc.

[vlad01]

yeah it will be a pretty small cam. only looking for 20 odd % increase in overall power with similar powerband, upped a little in to higher rpm, and i'd be happy.

the VR stock made peak torque at 2400-3200 rpm peak hp at 4700rpm at 146hp and thats a lot lower rpm range than factory with nothing more than exhaust and air intake. It great to drive!

Biggvl's customer gemini with VN engine made a real healthy 170+ hp at the wheels with I think a crow stage 1 and milled hypatec to get somewhere around 10.5 CR and ported heads.

its peak HP was about 4800 if I recall from dynoing it. It made fantastic toque at low rpm. It would be a ball to dive as a daily. Mind you it had awful home made headers and just came back from getting custom designed and made headers so it should make a lots more now once it gets another tune.

Im aiming for something similar for my engine.

[vlad01]

have you thought about getting flat tops and have a bit milled off the top of them ? shouldn't take much to get the comp down where you need it ?

or alternatively flat tops and mill a smaller dish into them than the normal pistons have tailored to your needs ?

thats what biggvl did and they work great. cheap too at 170 odd for the set.

[immortality]

Those Crow cams are tiny. I think the MACE stage 1 is bigger than the Crow stage 3 cam.

That's a huge jump going from 8.5:1 to 10.5:1 in a VN with such as small cam. Obviously worth it though

[vlad01]

Those Crow cams are tiny. I think the MACE stage 1 is bigger than the Crow stage 3 cam.

yeah it is. I looked them up last night. I was trying to figure out if crow used cam lift or valve lift number and I compared to comp cams and thought that crow used lob lift but actually its valve as well. So they just have small lift, durations are similar though crow use split durations typically like factory did.


funny thing is the stage 3 they claim power range from 2200 to 6300? that sounds absurd and undrivable for how small the cam is, but is that with stock CR? probably why it would be that shit lol

was just reading some of your posts on JC before regarding some people builds with stage 3. how the ***k can you get 22l/100 cruising.

I can't even get over 10L much even going flat out all the time.

[immortality]

Yeah, it seems stupid not to make use of the good head flow the ecotecs have with higher valve lifts.

If those are builds with Crow cams then it's probably the tunes supplied with said cams.

[vlad01]

its not ecotec, VP engine. comp dont make cams for pre eco as far as i know. I was just using them for comparison.

[immortality]

Ahhh,

Have you looked at the Camtech grinds?

http://www.camtechcams.com.au/hold_6cyl ... llhyd.html

[vlad01]

Yeah, it seems stupid not to make use of the good head flow the ecotecs have with higher valve lifts.

If those are builds with Crow cams then it's probably the tunes supplied with said cams.

I can tell you for certain, crow's memcals are absolute worthless junk. AFR all over the shop, timing low and very very rich, low on power. Made less than my VR


this gemini ran AFR on the crow memcal around 10.5- 11s. so rich my cloths smelt like 40 year old volkwagen crankcase sludge. yes it has that unique smell, black smoke, fuel smelly black oil in no time, headaches and tired for few days after.

12P out of the box was heaps better and now its pretty spot on fuel wise, smells like gun powder so its good Its got no cat you see.