Pete Posted March 19, 2008 Share Posted March 19, 2008 I read the other day of a drift Supra where they've mated a 1JZ head to a 2JZ block to achieve an extra 500cc displacement and it is "less restrictive and flows better"? I've never heard of this being done before? Anyone else? Quote Link to comment Share on other sites More sharing options...
SimonB Posted March 19, 2008 Share Posted March 19, 2008 Nah, it's an old internet myth that the 1JZ head flows better. It's been doing the rounds for ages and completely untrue. Quote Link to comment Share on other sites More sharing options...
paul mac Posted March 19, 2008 Share Posted March 19, 2008 dont they do this in the states but the other way round and call it a 1.5 jz ? Quote Link to comment Share on other sites More sharing options...
garethr Posted March 19, 2008 Share Posted March 19, 2008 I reckon it's only worth doing a 1.5JZ (1JZ head on 2JZ block) if you already have a modified 1JZ. Otherwise you might as well use the whole 2JZ. It's easier to find aftermarket parts, for one thing. Quote Link to comment Share on other sites More sharing options...
Chris Wilson Posted March 19, 2008 Share Posted March 19, 2008 How changing the head alters displacement I don't know, displacement is a direct function of bore X stroke.. My head man didn't see anything particular to make him think the 1JZ-GTE head would flow better than a 2JZ-GTE one, and that's good enough for me I didn't go to the expense of having them flow tested though. Quote Link to comment Share on other sites More sharing options...
garethr Posted March 19, 2008 Share Posted March 19, 2008 How changing the head alters displacement I don't know.....Perhaps it was a Mk3, so what they actually changed was the block Quote Link to comment Share on other sites More sharing options...
Guest MrDave Posted March 19, 2008 Share Posted March 19, 2008 Apparently it has bigger less restrictive exhaust ports, but ive never heard of that before. Goes ok from what ive seen of it tho. Quote Link to comment Share on other sites More sharing options...
JustGav Posted March 19, 2008 Share Posted March 19, 2008 I've heard rumours that the 2jz-ge head is also slightly better than the 2jz-gte head when it comes to flow, I believe this has been backed up by some flow testing but can't find the info so regard it as flawed info. Quote Link to comment Share on other sites More sharing options...
Mike M Posted March 19, 2008 Share Posted March 19, 2008 How changing the head alters displacement I don't know, displacement is a direct function of bore X stroke.. My head man didn't see anything particular to make him think the 1JZ-GTE head would flow better than a 2JZ-GTE one, and that's good enough for me I didn't go to the expense of having them flow tested though. Depends on the amount of cc's per cylinder chamber on the head i thought plus piston size and stroke. You get the chamber volume kits with the syringe for measuring or is that for compression ratio. Maybe the 1jz-Gte head has bigger cylinder chambers. Found it although not for Toyota you get what i'm waffling on about. http://www.msgulfcoastvwclub.org/TechPages/Tech10.html Quote Link to comment Share on other sites More sharing options...
carl0s Posted March 19, 2008 Share Posted March 19, 2008 How changing the head alters displacement I don't know, displacement is a direct function of bore X stroke.. My head man didn't see anything particular to make him think the 1JZ-GTE head would flow better than a 2JZ-GTE one, and that's good enough for me I didn't go to the expense of having them flow tested though. I think the point is that they changed the block of the 2.5 litre 1JZ engine to a 3 liter 2jz block, IYSWIM. Quote Link to comment Share on other sites More sharing options...
carl0s Posted March 19, 2008 Share Posted March 19, 2008 Perhaps it was a Mk3, so what they actually changed was the block d'oh! Quote Link to comment Share on other sites More sharing options...
Digsy Posted March 19, 2008 Share Posted March 19, 2008 Depends on the amount of cc's per cylinder chamber on the head i thought plus piston size and stroke. You get the chamber volume kits with the syringe for measuring or is that for compression ratio. Maybe the 1jz-Gte head has bigger cylinder chambers. Found it although not for Toyota you get what i'm waffling on about. http://www.msgulfcoastvwclub.org/TechPages/Tech10.html The combustion chamber volume is not taken into account when you work out the engine's displacement, but it is when you work out the compression ratio. Quote Link to comment Share on other sites More sharing options...
Tom Posted March 19, 2008 Share Posted March 19, 2008 good timing for you guys as I'm just about to get my 1JZ engine built, here's a side pic of the ports of my head, Intake Exhaust Exhaust close cams the ports are tiny and especially small compared to an RB26 engine which is being built next to this, the RB26 ports were much much bigger, intake and exhaust. as soon as the head was apart I told my mechanic about this rumour but it is hard to believe the 2JZ has a smaller ports than this. If anyone wants to I can take mesurements etc incase people want conclusive proof? but my head will be ported as there's a lot of potential there Quote Link to comment Share on other sites More sharing options...
Mike M Posted March 19, 2008 Share Posted March 19, 2008 The combustion chamber volume is not taken into account when you work out the engine's displacement, but it is when you work out the compression ratio. Cheers for that. Quote Link to comment Share on other sites More sharing options...
SimonB Posted March 19, 2008 Share Posted March 19, 2008 If you search around there's a thread somewhere where one of the guys in the states did actually flow test the heads - the 2JZ flows significantly more as you would expect. There's also something about the GE head vs the GTE. Basically the combustion chamber volume in the GE head is smaller, which is the main reason why the compression ratio is higher for the GE than the GTE. It doesn't flow any better either. Quote Link to comment Share on other sites More sharing options...
Muffleman Posted March 19, 2008 Share Posted March 19, 2008 Has anyone modified the 2JZGTE head and flowtested it afterwards ? Looks to me that some serious gains could be had in headwork on the 2JZ. Quote Link to comment Share on other sites More sharing options...
Pete Posted March 19, 2008 Author Share Posted March 19, 2008 How changing the head alters displacement I don't know, displacement is a direct function of bore X stroke.. That's always been my understanding of it and 500cc seemed an awful lot. The article is from a magazine a friend brought in - he works at the place which prints it and thought as I liked Supra he'd give me a copy. Nice thought. It's some chap called Miguel Marini with a BN Sports (AKA Darlek) body kit on it. The engine is a specially built hybrid consisting of the bottom end of from a 2JZ-GTE mated to the cylinder head of its older cousin, the 1JZ-GTE. The combination yields an extra 500cc of displacement and takes advantage of the less restrictive exhaust ports on the 1JZ heads to deliver more power Actually now I've re-read it they're running HKS pistons - maybe the stroker kit? It's a bit of a chavvy mag so no doubt they've got no idea what they're talking about. It's just seemed a bizarre thing to do! Quote Link to comment Share on other sites More sharing options...
Pete Posted March 19, 2008 Author Share Posted March 19, 2008 Video here Drifting in his Supra all over Europe Quote Link to comment Share on other sites More sharing options...
Guest suprabass Posted March 19, 2008 Share Posted March 19, 2008 Hi guys just seen this tread I actually now own the above mentioned BN sports supra it runs the 1.5JZ setup. Quote Link to comment Share on other sites More sharing options...
Guest DaveWilko Posted March 19, 2008 Share Posted March 19, 2008 The 1.5JZ setup refers to a 1JZ block with a 2JZ head bolted on as the later head flows better. Read about it recently though I can't remember where Quote Link to comment Share on other sites More sharing options...
Guest DaveWilko Posted March 19, 2008 Share Posted March 19, 2008 dont they do this in the states but the other way round and call it a 1.5 jz ? Quote Link to comment Share on other sites More sharing options...
Pete Posted March 19, 2008 Author Share Posted March 19, 2008 Hi guys just seen this tread I actually now own the above mentioned BN sports supra it runs the 1.5JZ setup. Ah cool. It looks like a bit of a monster. Have you seen Modified Motors April issue over there yet? Apparently it's an Irish magazine. Quote Link to comment Share on other sites More sharing options...
Tom Posted March 19, 2008 Share Posted March 19, 2008 The 1.5JZ setup refers to a 1JZ block with a 2JZ head bolted on as the later head flows better. Read about it recently though I can't remember where I'm pretty sure its the other way round, why would people use the bottom end of the 1JZ over the 2JZ? Quote Link to comment Share on other sites More sharing options...
Tom Posted March 19, 2008 Share Posted March 19, 2008 1.5Jz soarer Quote Link to comment Share on other sites More sharing options...
Guest DaveWilko Posted March 19, 2008 Share Posted March 19, 2008 The cars this was done to were Mk3 Supes, hence 1JZ already in place ;D Quote Link to comment Share on other sites More sharing options...
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