1.5jz vs 2jz spool time
- Thread starter rshn117
- Start date
Can we please tone the fucking attitudes down a notch people? This thread is dangerously close to heading to the bit bucket, and when it does a couple of people are going to wind up going with it....
Ahem.
With that said, I no longer have the data, but back at AAP we did some flow work on the 1JZ head and it was, if I recall correctly, capable of about 85% of what the 2J head could flow even after a full port job on both heads.
That's really not bad at all, considering just how much a ported 2j head flows...Supracentral;1823688 said:
Still haven't heard back from the OP on what sort of power level or intended use of the car he's going for here. That will help clear things up quite a bit.
Supracentral;1823688 said:
Could I ask why people do the whole 1.5jz if the 2j head outflows the 1j head? What would be the whole purpose? I thought it was done because the 1jz head had a better flow.
piggyback tune on pump, i would guess around 500
yes the 2jz is "better" yes it flows more, im interested in finding out the difference in what the hp/tq graphs would look like with the two heads. the port velocity is different i do not know exactly how that effects hp/tq so im doin a bit of studying. i know its all in the tune but it was always a bit odd to me that a 1jz with gt35r could have a graph that is very similar to a 2jz with a gt35r, there is a 14.5mm stroke difference i would of imagined the difference in tq would be more pronounced under boost.
ill take some rough measurements of ports between the two and post em up later, they do look very similar the 2jz is just bit bigger over all more so on the exhaust side
yes the 2jz is "better" yes it flows more, im interested in finding out the difference in what the hp/tq graphs would look like with the two heads. the port velocity is different i do not know exactly how that effects hp/tq so im doin a bit of studying. i know its all in the tune but it was always a bit odd to me that a 1jz with gt35r could have a graph that is very similar to a 2jz with a gt35r, there is a 14.5mm stroke difference i would of imagined the difference in tq would be more pronounced under boost.
ill take some rough measurements of ports between the two and post em up later, they do look very similar the 2jz is just bit bigger over all more so on the exhaust side
IndigoMKII;1823763 said:
Simplicity in wiring really. If you've got an MA70 chassis, a 2J shortblock and a 1JZ frontcut, you've got everything you need to just bolt it all together. If you run a 2J head you've got to retrofit the 2JZ electronics into a car that was never intended to have them.
IndigoMKII;1823763 said:
Headflow is not everything. Heads that Flow great usually make more hP but less tq. heads that Dont Flow well usually make less HP but more Bottom and and Mid range tq. Example Honda 1.6 and 1.8L Vtec engines. they heave serious headflow and usually make more Hp than even engine slightly bigger mod for mod, but dont make great TQ. the b18b (LS Non Vtec engine) makes quite a bit more TQ than the same size Vtec engine but less power. and its power is consistent with the power of other 1.8L engines from other makes. same thing with the TPI 350 l98 engine. heads flow like complete ass, the LSx engine shave FAR superior head flow. but cannot produce the TQ of an L98. but the L98 cant make the HP of an ls1.
As far as JZ engines go the 1jz head moves air much faster than a 2jz head. it just doesnt carry as MUCH air. the port velocity to me is more important than flow when it comes to these engines. Th answer to the OP's question was all being equal which would spool faster. 9 times out of 10 the 1.5jz will spool faster, especially with factory 1jz cams and intake, but will 9 times out of 10 make less Horsepower than a full 2jz.
rshn117;1823765 said:
I had two dynos that Could show you the difference but i can only find one. this is my personal friends 1.5jz
He made 923 and 750 foot lbs of Tq. and not only that but at 3000 rpms he made over 200 foot lbs. and this was on c16 not e85 which everyone knows e85 will increase TQ. You will NOT find a full 2jz making low 900's with 750 tq on c16. the 1jz head creates Monster TQ and spool! just so you know he currently makes 949 and 800 foot lbs of tq on e85 and about 230 tq @3k rpms
2jz head flow= more hp
1jz FAST flow = more tq all over the place
Btw this dyno was 4 years ago. and not with a Fancy Billet super aerodynamic modern day Turbo.
Another good reason to do a 1.5jz is because you already have a good head, like mine. Ported VERY nicely, already have aftermarket cams... of course it's not *so* much work that I wouldn't consider a 2j if this thing blew up, but still... it's a really nice head. I am really looking forward to seeing how it behaves when it has a real turbo that isn't a choke point on it's potential.IndigoMKII;1823763 said:
If you're only going to be looking for 500whp (unless you're just talking crank here), and overall powerband/response is important to you, then a 67mm turbo is a HUGE waste of potential there. Little example for you here, once upon a time, two years ago, I raced Albert on here. He had a 67mm journal bearing turbo (running roughly 12psi) on his 1j, along with intake, exhaust, and little else. I had (still have) stock twins on 12psi, stock intake/intercooler, 3" exhaust, a nicely ported head, and BC264 cams. Out come of this race? I pulled ahead by about half a car length at the start... and held that same advantage the entire time, up to about 125 (kph, wink wink, we were in Canada) or so. Reason I beat him? My powerband/response was better overall. The turbo setup on my car was better suited for the application.rshn117;1823765 said:
Now if he had been running that same turbo at it's 600ish whp potential, obviously I would have saw nothing but tail lights.
Another story, same setup on my end, racing Dustin (gurley0916 on here), along with a couple other guys. He also had a 67mm turbo at the time, on a 2j, I forget just how much boost he was running. Later that same day we both dyno'd, I laid down 320whp, Dustin 340whp. Same story though, I pulled away while he was waiting for that big turbo to come alive, and held that advantage until we stopped the pull.
The key to a good setup is how well you can flow air. If you deal with the basics (porting the head, intake, exhaust, cooling), and choose an APPROPRIATELY sized turbo for your desired power level, what do you end up with? A monster, plain and simple. I'm just saying you're wasting your time with a 67mm turbo these days if all you're hoping to break is the 500hp barrier. You'll get left in the dust by people with proper setups all day long because you're wasting potential with an oversized (and under utilized) turbo.
Holy crap man, the numbers (and revving, wow) seem right for a 1j, but damn... did he dyno in 2nd gear?Boostage;1823888 said:
A 2JZ is better then a 1.5JZ in every way. Just build the 2J and stop talking hypothetical differences of a couple hundred RPM.
I agree with the 1.5JZ spooling earlier in the RPM range (and faster between shifts), but making less power at high RPM. It has higher port velocity and that should help with turbo spool assuming the manifold is designed right. If you throw a china manifold on there that has runners 1/4" larger than the ports and a collector designed by a 10 year old then there will probably be no difference.
If you had a 1JZ in your car and got a 2JZ shortblock for a good price, it would be worth swapping in in my opinion. Otherwise a 2JZ is the way to go.
If you had a 1JZ in your car and got a 2JZ shortblock for a good price, it would be worth swapping in in my opinion. Otherwise a 2JZ is the way to go.
The bottom line has been and always will be that the 2JZ is superior when it comes to 3L.. unless like it's been said a gazillion times, one gets it for cheaper or a combination of that and already having a modded 1J head/don't want to mess with wiring again.
Also, trying to decide between a 1.5 and 2J based on spool time doesn't exactly speak wonders about logic. Why would you choose a motor that limits overall potential, when you could choose the optimum setup designed by the OEM to be the best match? Beyond that, there are so many ways to adjust response and power to one's liking. The difference in spool, regardless of RPM, is not going to be that big of a difference (for reference, I've had friends with all three combos: 1J/1.5J/2J).
Also, trying to decide between a 1.5 and 2J based on spool time doesn't exactly speak wonders about logic. Why would you choose a motor that limits overall potential, when you could choose the optimum setup designed by the OEM to be the best match? Beyond that, there are so many ways to adjust response and power to one's liking. The difference in spool, regardless of RPM, is not going to be that big of a difference (for reference, I've had friends with all three combos: 1J/1.5J/2J).
rshn117;1825002 said:
Smiley. But happy made more than 900 too. the cool thing with Smileys car not only does it make more tq, but it revs faster than any JZ motor I have ever seen even with a monster turbo. even Charles (RAW s2k) and Bid Daddy who both make over 1500 with Nitrous and GRP aluminium rods out of a full 2jz, doesnt rev as fast. his Tq is higher than theirs everywhere on the same boost level. I know all these guys personally and we all go to the same dyno and they have the same tuner (crispeed) and all running the same ecu (Haltech platinum 2000) and the motors built by the same person. If the Printer at the dyno still worked I would overlay the charts and print them, I might just try to get a snapshot from my phone when Im there again.
