actually sam's pic is not a 4AG head. i think.
i just had a look @ my small port head and it looks similar to 30psi's
this is all cool
has anyone noticed though how much the actual chamber shape has changed?
in 30psi' case if you're cramming 30psi in there its probably not so much of an issue, but, in the case of a NA motor i'd hazard at a guess it would make a difference somewhat.
sam's head pic shows the piece in between the valves which kinda comes down a fit bit between them, but, in the original pic (and 30psi' pic) this has been removed completely
any thoughts? i'm about to put my head on my 4AGE bigport/7 rib combo this weekend so really value any thoughts and opinions here
thanks guys
actually sam's pic is not a 4AG head. i think.
i just had a look @ my small port head and it looks similar to 30psi's
yeah I should of said so if I didnt, its a 7afe head, which putting your description in my words is that the 7afe heads have a significantly larger squish area than any 4age based head.
7afe had economy in mind when they designed it? 4ag had more performance in mind?
Last edited by jeffro ra28; 24-04-2008 at 06:32 PM.
perhaps barely...
current "economy" motors have more performance than older performance motors
"I'm a Teaspoon, not a mechanic"
"There is hardly anything in the world that a man can not make a little worse and sell a little cheaper" - John Ruskin (1819 - 1900)
AU$TRALIA... come and stay and PAY and PAY!!! The moral high horse of the world!
I am talking about "had" sorry. lol
current economy motors also have worse economy than they did previously too
(the 100kw 1.8 litre celica (only a couple of years old) i had to chuckle about when they were advertising 100 killer watts....ooooh you had that back in the late eighties well done
now back on topic...
thanks sam.....i wondered what it was from.
hmm its really tricky knowing if the increased squish area helps it or retards it in power. I believe some deshrouding is needed and amoung many things I am using motorbike heads as a reference in my quest for making a hybrid screamer.Originally Posted by jeffro ra28
grega: no problem. With the economy thing though could it just be from the massive increase in weight small cars have copped over the years?
Last edited by Sam_Q; 24-04-2008 at 10:13 PM.
With the flow of one valve hitting the others flow in the center of the chamber, there isn't much that can be done that would make a difference, compared to working on that solid wall that partially surrounds each one.Originally Posted by jeffro ra28
I'm guessing that a rougher surface has more surface area and conducts more heat whether covered/insulated by carbon or not, and that I don't want to put more heat into the head around the exhaust valves, cool & reduce the combustion pressure of the power stroke and put more heat into the cooling system.
'I've scrapped better.' John stated when asked about the car by the guy with the silver tipped cowboy boots!
that makes sence but it all sounds like something that would never have any real world effect. Perhaps they just leave it because they know it wont do shit all either way?
Originally Posted by Grega
As I said... the cost to do my head was less than .75cc, or about 2%.
Information is POWER... learn the facts!!
Hmm, I have a spare bigport head laying around here. I'll have to get it crack tested etc, then try some of this stuff out....
Hmmmm, a photo of OEM 9.4 to 1 piston(on the left), and OEM 10 to 1 piston....Originally Posted by jeffro ra28
more surface area??? better heat dissipation?
Information is POWER... learn the facts!!
There maybe a couple reasons why they (TRD) polish a certain part of the chamber. Here's how I see it. They remove minimal material from the chamber to achieve the highest allowable CR as per FISA rules and, this is for N2. If they remove more, chamber volume will be increased, thus lowering the CR.
Now for GROUP A, 10.8 cr for rally (36.5 cc/chamber) and 11.8 cr for race (33 cc/chamber).
Or maybe, this is a FISA restriction and they are only allowed to touch those areas on the chamber. I think it's all about the rules. My two cents.
Should reshaping the combustion chambers/removing material be left to the pro's or can a novice have a decent hack at it with relatively good results?
Slightly off topic, but ive got my 3rz apart at the moment, and considering im chucking in a 3mm headgasket, im thinking of removing the quench areas totally (from my little knowledge they will just add to detonation when using a big headgasket). and wanted to know if i should give it a shot.
Ill post a picture up tomorrow showing the chambers, and you guys can tell me what i should be removing (ive got a spare anyway so if i make a mistake im still ok).
Also ive attached a pic of supercrowns DIY head (hope he doesnt mind), it seems he has too totally removed the quench zones with good success (am i seeing wrong?). Discussion?
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