1.5jz vs 2jz spool time

[rshn117]

havnt had much luck finding info on how the two engines behave with same setups other than the typical 2jz>1.5jz

say both run a 67mm with 1.00ar to 1-1.5bar same exact setup, same ecu, same factory cam just slight compression difference of 1.5jz

would the two feel any different? would the 1jz supposed higher port velocity make a difference in spool with a mid-large turbo?

any thoughts, experience?

 

[Mr Bojangles]

Well this is a question that is kind of irrelevant because you wouldn't build the two engines the same. For a lower compression 2JZ you would run smaller cams and a slightly smaller .ar and your turbo would spool fine.

How does that compare with a 1J? Well you would build the setup for the 1J based on the compression it has and what it can do. Not to mention rpm range and how long you will stay in boost, that is much more important that when the turbo spools.

If you built two different engines with different behaviors the exact same way then you'd be foolish.

I'm not surprised you've had trouble finding an answer because there really isn't one.

 

[Mr Bojangles]

I guess you could think about it this way, a 3.0 litre is moving more air that a 2.5 litre when running at the same rpm right?

Higher compression dictates that the air coming from the engine will most likely have a more forceful impact when it hits the turbine wheel which means it would spool it more quickly.

You could say a high compression 3.0 litre motor will spool a turbo more quickly than a low compression 3.0 litre and be correct.

In your case you have two different variables involved that affect spool which are compression that favors the 1J and displacement which favors the 2J so deciding which spools faster is kind of a wash.

The benefit of the larger displacement motor is that its going to move more air all the time which means faster turbine speeds and more psi which means more power potential if we are talking about identical setups.

 

[OneJArpus]

^He said 1.5JZ So 3.0 Bottom end on both but different heads... But your answers aren't far off... Direct them towards the flow of a 2JZGTE head vs a 1JZGTE head and they about the same principle.


The 2jz head flows more then a 1jz head. So if i denticle the 2jzgte engine WILL flow more and boost earlier (no matter how slight) then a 1.5jz because the head isn't as flowing as the 2jzgte head. There are flow charts of all heads on supra's floating around


Slight compression difference would still be defeated in my opinion by the better flowing head. NO actual data to prove though.

 

[rshn117]

...let me simplify the question. id like to know what difference if any there would be between two engines in spool up time and powerband. only difference is the heads. for example say both are 3.0L, 8.5:1 cr, usdm 2jzgte cam, 1jz ecu + emanage, 67mm 1.00ar, same mani and exhaust, same fuel setup, same tune on 93 so the only real difference is head design and intake manifold, im interested in how that effects the power band. i have no experience with single powered cars but i would assume that spool up may differ a few hundred rpm and the 2jz may have higher peak power and flatter torque curve towards redline. mainly a question for experienced members who have built/tuned multiple engines
thanks

 

[Mr Bojangles]

I'm clearly not qualified to answer this hypothetical question.

 

[rshn117]

trying to differentiate port velocites and exhaust harmonics maybe a bit much i guess.

 

[AlterEgo]

I think the 1jz has a higher flow rate on the exhaust ports versus the 2jz if memory serves me correctly. If anything, your 1.5JZ will spool the same as a standard 2jz, give or take 100-300 rpms worth. Not enough to even worry about.

 

[hvyman]

Nope. 2jzgte head flows better than all the other.

Op are you trying to decide which engine to use based off turbo spool time?

 

[rshn117]

i know the 2jz flows more thats obvious, spool time difference should be insignificant if there is like a 500 rpm difference then theres a big wtf factor. powerband is my concern and how the hp/tq graph looks like with the two heads at various boost levels 1-2 bar with a 67ish mm. i would assume they would be about the same until the 1jz head flow becomes a limiting factor and the 1.5jz would drop off in hp/tq where as the 2jz wont in 600+ range but assumptions dont get you far. ive seen 1jz tq graphs that are just plateaus into redline, my unmodified 1jz on stock boost made 330rwhp/380rwtq years ago made no sense still doesnt. so id like to know what differences there would be if any in the power/tq bands given a set tune and setup

 

[Dylan JZ]

just by looking at these, one should be able to answer the questions above..

 

[IBoughtASupra]

This thread should be closed after your post Dylan. It tells your the answer. I was looking for those graphs to add to the JZ thread but I couldn't find it. I am going to add it now.

 

[Boostage]

The graph above is not real. where that graph originated from the OP said it was his theory and he drew it up. Honestly its the stupidest thing I have ever seen. It makes no sense to make a chart based on what you think instead of actually doing a flow test. for the record I have seen a full 2j and 1.5j on the same motor. the 1.5j spooled faster and made more peak tq but less peak hp.

Restrictive Ports=less hp more tq
Open ports= More Hp less TQ

Exhaust Speed with a 1.5j will be greater than a 2jz, it just wouldnt have the volume

 

[NecroCyde]

The graph above is not real. where that graph originated from the OP said it was his theory and he drew it up. Honestly its the stupidest thing I have ever seen. It makes no sense to make a chart based on what you think instead of actually doing a flow test. for the record I have seen a full 2j and 1.5j on the same motor. the 1.5j spooled faster and made more peak tq but less peak hp.

Restrictive Ports=less hp more tq
Open ports= More Hp less TQ

Exhaust Speed with a 1.5j will be greater than a 2jz, it just wouldnt have the volume

Really??? So nobody ever actually did a flow test in any shape or form to get the above graphs!?@?!@?!? If so the person should get an atomic swirlie for posting such misinformation and BS. Like people are going to be making purchasing and financial decisions based on info like that and if its bogus or even worse, a personal opinion, bereft of actual facts or practical knowledge. Then their results would suffer. So those charts are for sure just hot air and digestive smells? Or is that not fact either?

 

[Boostage]

Really??? So nobody ever actually did a flow test in any shape or form to get the above graphs!?@?!@?!? If so the person should get an atomic swirlie for posting such misinformation and BS. Like people are going to be making purchasing and financial decisions based on info like that and if its bogus or even worse, a personal opinion, bereft of actual facts or practical knowledge. Then their results would suffer. So those charts are for sure just hot air and digestive smells? Or is that not fact either?

Yes for sure its BS.. here is the Original thread http://www.supramania.com/forums/showthread.php?99476-Supra-Head-Flow-(5M-7M-1JZ-2JZGE-2JZGTE)

 

[AlterEgo]

Nope. 2jzgte head flows better than all the other.

Op are you trying to decide which engine to use based off turbo spool time?

Sorry, I should have been more clear. I meant to say the 1jz exhaust ports are bigger that the 2jz exhaust ports and the 2jz intake ports are bigger than the 1jz intake ports. I was not talking about overall head flow. Overall form on stock form, 2jz wins, this is proven fact. Will it make any noticable difference in spool time in regards to OP? No.

 

[te72]

...powerband is my concern and how the hp/tq graph looks like with the two heads at various boost levels 1-2 bar with a 67ish mm.

OP, just how much power are you looking for here? If powerband is your main priority, why in the world are you going with a turbo that big, with an A/R of 1.00+? Now, if you're looking to approach 1000whp, don't let me stop you, but at that turbo size, you're gonna be lagging, lagging, lagging, then holy SHEEEEEEEEEEEETTTTT!

Now, if you *are* going for power levels like that, but still want good response and powerband, may I suggest cams, porting the head, and maybe even a bit of nitrous to get the turbo going?

 

[IBoughtASupra]

The main thing when trying to make power is knowing how much you want first...then you the choose parts.

You won't use a 67MM turbo for a 400HP 1JZ. You'd use a 35R. You won't use a 35R if you are looking for a 700HP 2JZ, thats where you'd use the 67MM.

 

[rakkasan]

This thread should be closed after your post Dylan. It tells your the answer. I was looking for those graphs to add to the JZ thread but I couldn't find it. I am going to add it now.

When did the 1JZ/2JZ section become such a heavy handed, socialistic forum?

 

[IBoughtASupra]

There is no point in comparing the 1.5JZ to a 2JZ. It's obvious that the 3.0 head is going to flow better and the head is the only difference but then you can argue compression of the 1.5JZ as well since it's not definite since there are options for the headgasket thickness and so on.

Then selecting a motor based on spool time is just plain retarded.