High Rev 2jz-ge - Lexus IS Forum
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post #1 of 6 (permalink) Old 07-03-2019, 05:38 AM Thread Starter
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High Rev 2jz-ge

I'm doing a n/a build and one of the things I'm looking to do is increase the RPM range. I'll be possibly looking into shimless buckets, knife edging the crank, some porting, and itbs. Not sure how much of this will actually make it into the car but it's all on the list of wants. I'm not trying to increase the rpm range just because, I'd like it to be useful. So I suppose my question is who has done mods to move past the 7.5 redline and were they able to get any benefits from it.
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post #2 of 6 (permalink) Old 07-03-2019, 02:01 PM
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Assuming you are Auto? You'll probably need a standalone to raise the RPM. Auto ECU has a RPM limiter on it to protect it from over revving. Also, if you are stock (as in not boosted, bolt-ons doesn't do much to these cars), for me, there are no benefits of raising the RPM besides maybe staying in the whole 170whp a second longer. The money spent is not the worth it IMO.

Wanna go faster? Press the gas pedal harder!
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post #3 of 6 (permalink) Old 07-03-2019, 02:20 PM
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Originally Posted by DemonIs300 View Post
for me, there are no benefits of raising the RPM besides maybe staying in the whole 170whp a second longer. The money spent is not the worth it IMO.
An NA (turbos too, but that's a different discussion) engine will never see more than ~115% volumetric efficiency (VE). Very, very easy to get 85-90% (somewhere in the torque curve), pretty hard to get 100%, and extremely difficult to see 100+%.

The idea of headers, tuned length intake runners, etc - is to increase VE.

VE and displacement DEFINE torque. So assuming 90ish% VE and 3.0L displacement, your torque is defined. What is NOT defined, however, is at what engine speed that torque is made.

Put another way, every single NA 3.0L gas engine ever made is going to make just about the same torque, which is between 195-225lbft. That includes 1920s engines, our 2Js, Nissan VG30s, Schumacker's V10 Ferrari, and all the other 3 liters too.

What changes, is at what engine speed that torque is made. That, in turn, will change the power being made:

200lbft @ 4500 = 171.4hp (about right for 2JZ-GE)
200lbft @ 6500 = 247.5hp
200lbft @ 8500 = 324hp
200lbft @ 20,000 = 762hp (like the 1995-2005 V10s in Formula 1)

Whether or not it's "worth" the expense or effort is totally subjective, but objectively speaking, making your torque at higher speed means more power which can absolutely provide better performance.
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post #4 of 6 (permalink) Old 07-03-2019, 02:36 PM
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Quote:
Originally Posted by Hodgdon Extreme View Post
An NA (turbos too, but that's a different discussion) engine will never see more than ~115% volumetric efficiency (VE). Very, very easy to get 85-90% (somewhere in the torque curve), pretty hard to get 100%, and extremely difficult to see 100+%.

The idea of headers, tuned length intake runners, etc - is to increase VE.

VE and displacement DEFINE torque. So assuming 90ish% VE and 3.0L displacement, your torque is defined. What is NOT defined, however, is at what engine speed that torque is made.

Put another way, every single NA 3.0L gas engine ever made is going to make just about the same torque, which is between 195-225lbft. That includes 1920s engines, our 2Js, Nissan VG30s, Schumacker's V10 Ferrari, and all the other 3 liters too.

What changes, is at what engine speed that torque is made. That, in turn, will change the power being made:

200lbft @ 4500 = 171.4hp (about right for 2JZ-GE)
200lbft @ 6500 = 247.5hp
200lbft @ 8500 = 324hp
200lbft @ 20,000 = 762hp (like the 1995-2005 V10s in Formula 1)

Whether or not it's "worth" the expense or effort is totally subjective, but objectively speaking, making your torque at higher speed means more power which can absolutely provide better performance.
Right, that's the reason I put "for me" in it because it is subjective. For someone Rav4_Chic, going full N/A, it might be worth it. Just make sure the head work is done for it before raising the RPMs.

Wanna go faster? Press the gas pedal harder!
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post #5 of 6 (permalink) Old 07-03-2019, 06:29 PM
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RSV4_chic Major head work, bigger valves, shim-less buckets, and porting & polishing. You need a totally different set of cams. ( custom grinds ) let see. Also different intake with larger volumes. Along with throttle body. Bigger injectors and stand alone. With better fuel pump. Raise compression with custom pistons and good aftermarket rods. Better oil pump. Knife edged crank with crank scraper. I did not mention all the aftermarket studs and bolts.

Cons= more RPM more wear. HP gains are not super great for money.

Pro= would be great for a road course.

Careful & Consistent
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post #6 of 6 (permalink) Old 07-03-2019, 06:42 PM Thread Starter
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Quote:
Originally Posted by DemonIs300 View Post
Assuming you are Auto? You'll probably need a standalone to raise the RPM. Auto ECU has a RPM limiter on it to protect it from over revving. Also, if you are stock (as in not boosted, bolt-ons doesn't do much to these cars), for me, there are no benefits of raising the RPM besides maybe staying in the whole 170whp a second longer. The money spent is not the worth it IMO.
For now I am automatic, I'm in the process of getting the car ready for a manual swap. I'll be doing some minor motor work then (i.e., cam gear, cams, and pulleys) which will just be the start. I will put more work into it as I progress.

Quote:
Originally Posted by Hodgdon Extreme View Post
Quote:
Originally Posted by DemonIs300 View Post
for me, there are no benefits of raising the RPM besides maybe staying in the whole 170whp a second longer. The money spent is not the worth it IMO.
An NA (turbos too, but that's a different discussion) engine will never see more than ~115% volumetric efficiency (VE). Very, very easy to get 85-90% (somewhere in the torque curve), pretty hard to get 100%, and extremely difficult to see 100+%.

The idea of headers, tuned length intake runners, etc - is to increase VE.

VE and displacement DEFINE torque. So assuming 90ish% VE and 3.0L displacement, your torque is defined. What is NOT defined, however, is at what engine speed that torque is made.

Put another way, every single NA 3.0L gas engine ever made is going to make just about the same torque, which is between 195-225lbft. That includes 1920s engines, our 2Js, Nissan VG30s, Schumacker's V10 Ferrari, and all the other 3 liters too.

What changes, is at what engine speed that torque is made. That, in turn, will change the power being made:

200lbft @ 4500 = 171.4hp (about right for 2JZ-GE)
200lbft @ 6500 = 247.5hp
200lbft @ 8500 = 324hp
200lbft @ 20,000 = 762hp (like the 1995-2005 V10s in Formula 1)

Whether or not it's "worth" the expense or effort is totally subjective, but objectively speaking, making your torque at higher speed means more power which can absolutely provide better performance.
This is great information thank you so much!

Quote:
Originally Posted by DemonIs300 View Post

Right, that's the reason I put "for me" in it because it is subjective. For someone Rav4_Chic, going full N/A, it might be worth it. Just make sure the head work is done for it before raising the RPMs.
Yes, there will be much more work into it before any of this happens, but like I said before I'm not sure what will/won't actually make to the car. -RSV4-chic-
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