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Location:
NSW
Registered:
September 2003
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 Don't believe everything you read - 1JZ GTE
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Mon, 08 September 2003 11:03
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For those of you who are regular 1JZ types and for those that are just interested, I was a little disturbed by some of the information that is on the Internet about the 1JZ.
I am an Aircraft Engineer with quite a few years experience and quite a fan of the 1JZ. Currently in the process of sorting out the 1JZ for my MX83.
I came accross an article in my research that claimed that the head port sizes of the 1JZ exhausts were not the same size, 1 & 5 were smaller. So, I ventured into the shed to check it out, it all seemed a little unlikely to me. This particular article was written by a supposed "expert". At first glance, they do look smaller, however if you have a good look, they exit the head at an angle. You don't have to be an engineer to figure out that a tube cut at an angle will appear to be larger across the section. Any measurement of tubes / runners / pipes has to be done square to the walls. The point of this is that even experts can be wrong and the 1JZ head exhaust ports are exactly the same cross sectional area.
On a different note, for those out there looking at the single turbo conversion, what type of manifold design are you looking at? From my observations of the ports, they have been designed specifically for twin turbos, with the ports being pretty much a straight line from the valves to the turbo inlet. This asks the question if a manifold that comes straight off the head is in fact improving flow. If anyone has an argument with this, go ahead. I would suggest that two, three into one sections with a split pulse turbo housing would probably result in the best result, depending on how tight the space was available.
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Location:
Brisbane
Registered:
May 2002
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Re: Don't believe everything you read - 1JZ GTE
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Mon, 08 September 2003 11:50
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Who is this supposed expert who said 1JZ's have different sized ports? The first time I saw a bare 1JZ head the angle of the ports was immediately obvious. As you say its purpose is clearly to optimise flow for the twin turbo setup - some clever design there by Toyota.
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Location:
NSW
Registered:
September 2003
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 Re: Don't believe everything you read - 1JZ GTE
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Mon, 08 September 2003 12:02
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I would not ever mention names as that is likely to end you up in more trouble than it's worth.
By the way, the head was actually designed by Yamaha
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Location:
Brisbane
Registered:
May 2002
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Re: Don't believe everything you read - 1JZ GTE
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Mon, 08 September 2003 12:04
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Yeah, I've heard conflicting stories on that one. Do you have any solid info?
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Location:
NSW
Registered:
September 2003
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Re: Don't believe everything you read - 1JZ GTE
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Mon, 08 September 2003 12:11
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To be honest, I don't really mind which one it is, both design great engines.
But to answer your question, I have a few contacts within Yamaha and Toyota that will hopefully shed some light.
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Location:
Brisbane
Registered:
May 2002
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Re: Don't believe everything you read - 1JZ GTE
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Mon, 08 September 2003 12:18
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I'd be very interested to hear some real facts, so if you could do that it would be awesome! I agree though, both companies do excellent work and they've had a close working relationship since the 60's (I believe the 2000GT was their first joint venture).
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Location:
Canberra
Registered:
May 2002
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Re: Don't believe everything you read - 1JZ GTE
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Mon, 08 September 2003 12:18
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IMI you are quite correct, the diameter of each exhaust port is damn near identical when the angles are taken into consideration. The 2JZ-GTE exhaust ports follow a similar design concept.
For information, the 1JZ-GTE VVTi single turbo engine utilizes a very similar exhaust manifold to the twin turbo, except that the exhaust gases all flow to a single central point. Constraints of fitting these engines into engine bay appears to force the compromise.
regards Chuck
"Sumpies do it with more Thrust"
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Location:
UK
Registered:
May 2002
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Registered:
March 2003
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Location:
Adelaide, SA
Registered:
May 2002
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Re: Don't believe everything you read - 1JZ GTE
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Tue, 09 September 2003 03:47
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I must admidt, I read the same thing re: 1jz exhaust ports and thought "what the?". Why would an engine have smaller exhuast ports on certain cylinders... Didn't remeber it until I saw this post though.
As for the manifold designs, you can buy a manifold from turbonetics that joins the two 1jz manifolds into one - and retains the split-pulse divider. I've got a similar style manifold that I intend putting on my 1jz, once it has been modified to add the split pulse divider. From there it'll bolt up to a hybrid T04 with a mazda series 5 turbo exhaust housing (also split pulse). Hopefully it'll go some way to improving the lag on an older style turbo.
And I think yamaha is cast into the head somewhere too!
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Location:
Perth
Registered:
September 2003
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Re: Don't believe everything you read - 1JZ GTE
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Tue, 09 September 2003 04:33
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i'm personally not worried about the head design.
with a bottom end designed like a bank vault i'm willing to forego a bit of a factory 'mishap' if you could call it that.
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