High Compression Zook

[Big D]

Hi iv searched and this topic has bin covered then soz.

Has any1 ever put high comp pistons into there zook? it would be sorta turboing it but not...umm yeah anyways so would this be a good idea or a complete waste?

Thanks

Dylan

[GRPABT1]

Perhaps shaving the head might be cheaper/easier? I don't know if it's possible on these or not but it's done on plenty of other engines to up to C/R.

[want33s]

Stock compression for a Zook (1.3) is 9.5:1.... Unless you run it on Avgas or Methanol you don't want much more compression.
10-10.5:1 is about the limit on Premium Unleaded before damaging detonation occurs.

[Gwagensteve]

I agree -a lot of 1.3 zuks pinged from new under high load/high heat.

On its own I think it would result in a very small power increase and would result in more issues to deal with like timing accuracy and spark control and cam profile.... and then to the lottery of fuelling one properly.

Personally, I'd just go to and efi motor - most of these run higher compression anyway because of the accuracy with which they can be timed and fuelled.

Steve.

[Big D]

yea ok then. was just thinking as a m8 has a datsun 240 with high comp and that goes hard. guess ima have to save $$$ for a bigger engine

[mrRocky]

we skimmed the head to raise comp 1 point on a mates car. cost us $50
and doesnt even come close to pinging even with the timing well advanced , running on 98 octane. It is by far the best mod to do to a carby 1.3 ltr powerwise. drives with 31" tyres and standard gearing easily, will sit on 130kmh up hills in 5th.
note: dont try to skim any more off it as things get a little close for comfort.

[GRPABT1]

The GTi motors run 10:1 compression and run on 91 octane fine so I'd say there'd be a bit of room.

[St Jimmy]

Ive got 40tho of the head and second size pistons with a weber no pinging yet

[Moph]

Did you notice any difference on the throttle after the head shave and boring, boner59? Will be putting my recon engine back in this week which has had head shaved and second size pistons installed (had done 300,000ks).

[oozuk]

my old 1600 in my old hi-top ran a worked 1600 with 10.5:1 compression, ballanced bottom end, reground cam ported 1600 8V head, vernier cam gear, modifyed sierra carb and extractors and 2.5" exahust system

sounded awesome with the cam when you were ringing it's neck but for the amount of work that was done it wasn't worth it for the minor power gain, that's why i've gone the turbo route this time

[oozuk]

ahh it also sucked on regular unleaded, only liked premium i once blew a head gasket between 2 & 3 because of detnation from crap fuel, so high compression isin't all it's cracked up to be

[Gwagensteve]

The GTi motors run 10:1 compression and run on 91 octane fine so I'd say there'd be a bit of room.

But they have a much better combustion chamber design, and they're efi.

Steve.

[ofr57]

http://www.lowrangeoffroad.com/samengine.htm
low range offroad actually sell high compression pistons ....

[Big D]

so all in all, not worth it getting the head shaved?

also on lowrange4x4, the camshafts that they say to give more torqe, they any good?

[St Jimmy]

Did you notice any difference on the throttle after the head shave and boring, boner59? Will be putting my recon engine back in this week which has had head shaved and second size pistons installed (had done 300,000ks).

it had better pickup through the rev range but my old was so bad it's hard to pick but the fuel consumption is better it breaks unijoints if you try hard enough

[GRPABT1]

The GTi motors run 10:1 compression and run on 91 octane fine so I'd say there'd be a bit of room.

and they're efi.

Steve.

Yes yes they are

[mrRocky]

$50 to get it skimmed = a bigger gain than extractors exhaust and webber for less than a 1/4 the cost. i would say definately worth it especially with 31's and crap (standard) gearing

[Big D]

ok sounds real good bbbbuuutttt then and how bout pinging? i have no clue what it is but i hear its real bad if u hear a knocking sound. i dont wanto screw my engine up

[mrRocky]

pinging is another term for detonation which arises from a number of things but mainly compression ratio in relation to low octane fuel or more commonly incorrect ignition timing.
run it on premium (95-98) and check your timing
Then be amazed as you pull 4-5 car lengths on your mates 8v 1.6 ltr carby zooks with extractors.
the main principle of making power revolves around getting more air and fuel in and out of the motor as efficiently as possible. to get the best gain use a high flow air filter and exhaust about 2"

[Big D]

ic so regular fuel would be poo. also how is the fuel consumpsion? not much differernt im guessing?

[Gwagensteve]

more compression = higher combustion pressure = more chance of pinging.

Pinging is uncontrolled combustion in the chamber and is can result in broken pistons.

maybe 1 heat range colder plugs and 95 miniumm octane and it will be sweet, but as I have said, in 1994 I saw a brand new (<1000km old) sierra pinging its head off on a hot day.

Often what happens is that a car overheats, does a head gasket, and in the course of fixing it, the had gets a skim, upping the compression, but nothing is done to find the source of the overheating, so the car goes back together, goes really hard, overheats again, does another gasket and no-one knows what to do. I have taken quite a few phone calls about this problem over the years.

I agree that the availability of 98 octane has helped this problem, but it's still worth being aware of.

Steve.

[mrRocky]

if anything i'd say better, but with a bigger exhaust it may
be a bit worse, kms the motor has travelled will play part aswell

[St Jimmy]

a guy in newy just done a moter up and he got his head hemi fide? he is a old time spanner spinner so he knows what he is doing next time i take the head off i'm getting converted as his goes hard

[MightyMouse]

As a bit of a side line - something to consider is whats the worst fuel quality your going to have to run ?

Around town 98 octane is available, but if you having to fill in the middle of nowhere then do you have a choice of fuels ? The storage life of 98 is also quite short, and with low sales it can be stale by the time you get it.

Even standard unleaded can be very average out of the "big smoke".

So if raising the compression means you MUST run 98 octane the you might be limiting your trip options.

Modern EFI systems are a different stripe of cat however and have the ability to adjust for octane variations.

[alien]

you can buy "octane booster" at supercheap (hydrocarbons)... its expensive in the scheme of things, but if you bought it in bulk for a long trip to top up your 92RON fuel to 98 then you'd be right... your wallet on the other hand...

[mrRocky]

you dont have to run 98 octane, we advanced the timing right up and still couldnt get it to ping and that was on the fuel that had been in the tank for 6 months. NOTE: methanol is only $1 a litre - and no cooling system needed

[St Jimmy]

you dont have to run 98 octane, we advanced the timing right up and still couldnt get it to ping and that was on the fuel that had been in the tank for 6 months. NOTE: methanol is only $1 a litre - and no cooling system needed

where you can get it every where in newi say no they dont sell it anymore used to run my honda four on it yes I'm that old that i owned a cb500 four

[over land 4x4]

try some of this stuff

http://cgi.ebay.com.au/CHEATER-NITROUS- ... dZViewItem

lol

[MightyMouse]

mrRocky am i misreading you - stale fuel, high compression and timing advanced right up didn't get it to ping ?

What compression is it running - how much did you take off the head ?

And what changes have you made to run methanol ?

[mrRocky]

i was only suggesting methanol as an alternative fuel, as it has an extremely high octane rating. we raised compression 1 point over standard, which my mate at the head shop said was the absolute max before the valves make contact with stuff there not supposed to.
stale fuel and alot of advance, we could not get it to ping at all.
However in saying that i have come across sierras completly standard that ping off there nut no matter what you do to them.
PING IS POWER