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Discussion Starter · #1 ·
ok yea.. this is a noob question... i should know the answer... in fact i probably did know the answer at one point...
anyways here it is... the jspec engine has 280 horsepower.. the us has 320.
i guess my question is why... I am trying to buy a 2jz gte but its hard to find us engines anymore... so whats the deal , why does the jspec have less? and is it like some easy fix thing , like its running less boost or somthing... damn lol
 

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I think that all japanese cars that are exported have to rated at less than 280hp, not exactly sure but i heard that somewhere. Notice also that the skyline was like 276hp, as was the evo, so i think it had to do with something in the shipping.
 

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feeding your habit
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displacement is the same, but the turbos are different, the injectors are smaller.

This is purely speculative, but I belive in japan that HP = high insurance/tax costs. It is cheaper to own the car if (on paper) it makes less power. Since the car is easily tuned and can make much more HP with slight mods. Marketing wise, it means the car costs less to own. Owners then do what they will.

In most states it is cheaper to insure a NA supra rather than a turbo for the same reasons. That is one significant advantage to buying a NA and making it a TT or single.... cheaper to insure, less excise tax, etc.

-M
 

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The differences are less than the official ratings suggest. I'm pretty sure the "false" hp rating issue applies to cars sold in Japan but they don't change the rating for sale in other countries unless something in the design changes.

But there are some hardware reasons why the JDM was rated lower, like the smaller ceramic turbos used on JDM Supras and a few other "minor" details, plus they are also tuned differently by Toyota.
 

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J-Spec 4 Life
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out of all the jdm cars that were made in the us the supra :( was the only one that carried the true hp rating. the gts skyline is just a piece of shit. quite possibly the worst car in stock form IMO. ive many and they are just shitty. whereas the gtr has the 276 hp rating but in reality has allot more. but the supra is really 280 from what i understand. 14 sec 1/4 in stock form. us 13.5ish???

i dynoed my car with only air filter and cat back exhaust and did 297 (no downpipe)

the engine themselves can handle the same amount of power though.
 

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There is law in Japan that says you can't have a car above 280 horses... i may be wrong but this is wat i've been told... therefore as many people have mentioned the skyline was 276 and look at the 350z its 280 and so on... none of the cars can be above 280 from the manufacturer...
 

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There is a "gentlemens agreement" stating that cars made for the japanese domestic market would have only 280 bhp. Although there are rumors sayin that it has been recently removed. However BPU J-spec's do put out around 400 ish crank hp
 

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Well I'll find out soon how much HP the J-spec motor puts out. I'm runing the J-spec Turbos and Injectors, along with the ECU. The only mods I have are Intake, DP and Super Drager Exhaust. I went to Dyno the car today, but they turned me down due to how busy they were at the time. I'll get it done next week or this weekend hopefully. I'm interested to see how much I'm putting to the wheels...eh Wheel (since I don't have LSD).
 

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J-Spec 4 Life
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I dynoed 297 with just intake and cat back exhaust (no downpipe)
do not put a downpipe on teh stock jdm twin turbo setup
your boost will sohot up to 20+psi
wastegate is tool small
 

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Nissan is going to break the agreement with the new Skyline. The "Gentleman's agreement" was put into affect becasue of the huge power wars that are now goign on between German auto makers. With huge 12 cylinder cars pushing massive power. From what I heard Japan did not want that and asked the auto makers not to rate the cars any higher than 280. The agreement has been broken however. Means we could see some good stuff from Japan very soon.
 

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JDM_trdsupra_tt said:
I dynoed 297 with just intake and cat back exhaust (no downpipe)
do not put a downpipe on teh stock jdm twin turbo setup
your boost will sohot up to 20+psi
wastegate is tool small
Yeah tell me about it. I'm doing it right now. But I'm only allowing it to go up to about 14-15 psi. But I'm working on putting in a restrictor plate very soon.
 

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MkIVSylver said:
ok yea.. this is a noob question... i should know the answer... in fact i probably did know the answer at one point...
anyways here it is... the jspec engine has 280 horsepower.. the us has 320.
i guess my question is why... I am trying to buy a 2jz gte but its hard to find us engines anymore... so whats the deal , why does the jspec have less? and is it like some easy fix thing , like its running less boost or somthing... damn lol
The difference between the jspec and the us is the turbos and the injectors. Out of the factory from Japan all cars cannot exceed 280HP. I don't know why they have this law over there, but its there. If your planning on upgrading to single then there is no difference between the us spec and jspec motor.
 

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SUPRAS FOR LIFE
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cams are different in the j-spec motor as well....
 

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I've got a japspec car, japspec turbos have ceramic turbines (bad), but have thicker shafts (good), 440cc high impedance injectors as opposed to 550 low impedance injectors, have a 224deg intake cam as opposed to 233deg intake cam, same exhaust cam. Japspec cars dont have the airflow meter, just map sensor.

also, they do have more than 280 HP stated, not quite up with the us spec, but around 300-310hp is a safe bet.

Another thing, it's common knowledge that most US dynos do have a tendancy to inflate hp readings, if your stock japspec engine is making more than about 300-310hp, it's not really :)
 

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Discussion Starter · #15 ·
hmm this is good news then. So then to get a jspec motor up to par it seems some new injectors are in order at least. new turbos... i might do it if i can find some cheap us models. Cam shafts probably not for a while... regardless it looks like ill end up just buying a jspec engine
 

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Kill Story King
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THe Gentlemens agreement that has been in effect only until recently was for 280 PS which is 276 hp in US standards. Most of there cars that are rated at 276hp are higher out the factory floor, but they must be advertised no higher then the 276HP or 280PS how ever you look at it(i.e. skyline and supra, evo, etc). Now that agreement is no longer in place and we are about to hit another supercar frenzy.
 

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i think nissan or some motor company did break the law once... because like i said japan has the law not to have cars over 280 horses but they tricked the government by showing rwhp numbers instead of crank...
 

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I thought the difference in the engines was a few parts as mentioned above but was the result of the J-spec detuning of the boost. The stock us turbos have 11.6 psi's and the j-spec is lower then that hence causing the major varation in difference of horsepower.
 
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