Forged or Not, how to tell? 4a-gze Vs 1g-gze

[twentyEight]

There's no 4K-GZE though...

[river]

Hi,

Yes, the 4K has a bore of 75mm and a stroke of 73mm.

The 3K has a bore of 75mm and a stroke of 66mm.

That's more your 1G size, as far as bore goes.

seeyuzz
river

[stradlater]

Well, I was gonna give him the benefit of the doubt, what with machining of bores and pistons and what not, but I think it's probably too far away to be of use.

Plus I know this guy is a liar at the best of times, so hey.

Why would you use 4k pistons?

[Mr Revhead]

well, normally youd use 1ggte/ze pistons in a 4k

[Billzilla]

The word that Stuart is looking for is hyperuetere ...... something, I can never spell the damn thing!
The photo of the piston above show a cast piston, that's for sure because you can see the casting flashes where the mold sections join.
A forged piston has no suchs marks, as they have are forged under the hammering of a powerful hammer that forces the metal into the piston blank mold.
The hyperwhatsit pistons are made in a process pretty similar to forging, but are squeezed under pressure rather than hammered. Thus the metal grain structure is similar to that of forging.
And .... I have some news from a reliable friend in Malaysia that got some 4AGZE pistons tested by a metalurgist, they may well be the hyperwhatsit type, not forged as we've thought for years.

[oldcorollas]

4K pistons are terrible. the ACL are better but their design is not good for much.. pin height is too high (long?), ring widths etc..

but 4AGZE pistons in a 5K

a 6mm bore seems like a lot of meat.. 3mm radius... so you'd want thick bores to start with..

what is the bore spacing of the 1G?

[oldcorollas]

The word that Stuart is looking for is hyperuetere ...... something, I can never spell the damn thing!

hyper-eutectic meaning more than the eutectic amount of silicon.

i wish i had brought the buggers with me, as i have more toys now

[Billzilla]

That's the one!

http://en.wikipedia.org/wiki/Hypereutectic_piston

[stradlater]

My bad. I've just been informed that there's no where near enough meet to bore a 1g to fit 4agze pistons.

That guy was telling big porkies...

I'd just LOVE to tell you guys who it was, cause it would certainly disprove a record that all you guys seem to know..

Ah, the defamation laws..

[twentyEight]

Tellorban!

Ooh, that's like Taliban!

[stradlater]

Don't say that word around here, we'll be in all sorts.. ;-)

[river]

Hi,

I'd just LOVE to tell you guys who it was, cause it would certainly disprove a record that all you guys seem to know..

So it's a company/engineering firm, or a Toymods poster?

Maybe they got confused between 4As and 4Ks and 1Gs.... plus the hypertitanic.. teutonic or tension or whatever they are pistons.

seeyuzz
river

[6BOOST]

Well, to dispell a few myths, a few lies, and answer a few questions.

The 1G pistons are not forged. This relates to every engine, NA, GTE and GZE, and all Gen's 1-3. All pistons have the same compression height, all pistons have the same pin diameter, and all are 75mm bore with interchangable rings. All 1G conrods are of teh same length, although there are 2 different big end sizes on the rods, early engines and to my knowledge all GZE and NA engines, have smaller big ends, and slightly wider, and the later model turbo engines have bigger diam big ends and are slightly narrower. This makes it impossible to interchange without some machine work, although strength wise, all GZE and GTE rods are the same thick meaty design and are as strong as each other, it is only the NA engines which are thinner forgings. As for crankshafts, the NA and GZE engines are the same, but the late model turbo engines(gen2-3) have a fully counterweighted crankshaft from the factory, these are FAR better and the pick to use.

The 1G bores while being a very thick factory casting, are about .180" at the thinnest point, at least on the 2 blocks I have sonic tested. That is 4.5mm, and per side, so if we machined the bore to the point where there was nothing left, we could effectively use a 9mm overbore. However keep in mind we obviously need some cylinder wall left, and 100-120" is widely regarded as a safe limit for any high hp or boosted engine making over 3-4hp/cu-in. So that gives us the option of an .80 per side overbore, or 4mm, taking us to 79mm.

For those that don't know, the HKS stroker kits of years gone buy had 79mm pistons. At this level of boring, even some blocks need to have the bores moved over, as they have thinner bores than the ones I have tested. I personally would be wary of going anywhere near these figures on a 500+hp engine, as the 1G has a rather poor rod/stroke ratio of 1.58:1, which is considered very low, and at pistons speeds approaching 4500ft/sec at 9000rpm, the stress and side loads on the bores is massive.

While I would imagine that it may be possible to fit a 81mm piston in the 1G bore, this would leave about 2mm of bore left, the heat generated would be large, and I imagine without grout filling the block, split bores would be a question of when, not if. I also have no idea of the 2 pin heights to know if they would fit and have the piston in the same position in the bore anyway, although i highly doubt it.

The stock cast pistons have proven fine at 550hp at the crank, this however was with C16, and plenty of ignition timing, I cannot say how they would fair and what the cylinder temps are with engines running LPG to say they would handle the heat. I have never broken a piston before, a had 1 let go but it was already stuffed when I put it in, and is of no direct comparison, although I can tell you the ring land is massive, the top ring sits about 5mm down from the top of the piston. I would keep your rev limit to 8500-8800rpm at the most, as the oil drain slots are cast, not drilled, and I fear that piston longevity would not be the best at 9000+rpm for extended periods, and may tear the piston in half.

I personally believe in high compression turbo engine, but use very large camshafts to bleed off midrange cylinder filling and reduce detonation. This may seem silly, but if you think about it, the higher compression brings the low end power up, then the massive cams bring this back down to normal, HOWEVER, at the same time, we get the high rpm benifits of the bigger camshafts, so we lose nothing/little down low over lower compression/smaller cams, but gain far more top end capabilities. The higher in the rpm you make peak torque, the higher the hp output will be, look at formula 1 with peaks at 17000+rpm.

If anyone has any specific questions about the1G, whether it is for building or general, feel free to pm me and I will help if I can Please keep in mind some thing are my opinion only, although all the 1g engine internal stuff is from first hand experience and visual knowledge, you learn a bit after pulling 15 or so apart

Regards.............................6BOOST

[stradlater]

RE: The oil drains, because I"m getting the modified block from you like we discussed, I won't have that problem will I?

[YelloRolla]

I think that he is referring to cast slots in the piston behind the oil control ring. All aftermarket high durability pistons have holes; this generally stops the piston crown making a bid for freedon during the valve overlap period at high RPM.