Why you shouldn't use a Japanese market tuned ECU?

[rsiwicki]

As per RB Motoring's website who import Skylines.....

Japanese market premium fuel is rated at 100 octane. They use a different method of determining octane in Japan. Here in the US -Southern California our premium fuel is 91 octane (RON+MON/2). Of course you can buy 104 unleaded from VP. You can also buy 100 octane uleaded out of the pump at some 76 stations. But for all practical purposes 91 is as high as you will get here in Southern California. Some places in the US you can get up to 94 out of the pump at "normal" gas stations.

Just something to keep in mind if ordering a JDM tunned ECU for our Q's.

[elwesso]

They offer 94 here in Indiana.

However, AKR (anti knock rating) is different from what the other coutries use. IE 98 octane is the same as 89 here....

[HeavyDuty]

Also, FWIW, some applications of OE JDM ECU's have dumb stuff like 112mph speed limiters, lack of vapor recovery, etc that cause issues when running them on USDM cars.

Disclaimer:No, I'm not specifically referencing a Nissan/Infiniti product or model, but rather a generalization of the differences between certain make/model vehicles. YMMV.

[QShip]

This is interesting stuff! I am interested in a JUN ecu for the G50.

[Q45tech]

Most JDM don't have the early warm up feature to light the precats in 30 seconds, thus JDM engines rarely have precats.

They [Japan] have/get tremendous benefits by using "EXTRA sweet lighter " crude oil [very low sulfur] and easy on emissions and cheaper to make octane.VS US refineries most of which are designed to function with "junk oil".

When Venezuela was off line Citgo had a serious problem find bad oil to use.......our refineries are optimized for the normal feed stock.

As to US octane the averaging "loop hole" allows cheaper processes which may not be suitable for all Japanese cars.

They try to make them work on our junk gasoline but as the compression goes up from piston and valve deposits and age effects many knock easier even on so called 93-94 average US octane.

Why the need for BG 44k and other combustion/injector cleaners and the intake [induction] cleaning and regular intervals........our gasoline is still too dirty.

The Europeans are in the same boat what works at home [in Germany] gets funky on US fuel.

[Q45RaCiNg_JR]

Hey everyone i haven't posted for awhile. Here's my 2 cents...

Well I don't think gas is the main factor you'll have to look at when getting a JDM ECU. I know of a person back in Cali who has a JDM Bodykit, Exhuast and a JDM Aftermarket ECU, He Told me he blew 2 transmission's because the chip prduces too much power for the transmission to hold up to. I think if i remember rightt.... it shifts around 7300... (I asked my dad and he said he remembers that it's capable of 10K but the motor will blow.)... I asked the guy how he likes it. He said " trust me when you don't even have to be in 2nd to beat a Saleen Mustang with Mods, you'll be proud of your Q." No his car does not top out at 115 or whatever. I'f I was back at cali I'd meet up with you guys and Take you to his house. He bought the car only with a Kit and then got the ECU for a Present from a company. The Dude has money... LOL. But he said Gas isn't a problem.

When I sat in the car when he started it up... Sounded exactly the same any other Q whould sound like with a modded EXH. He wasn't able to get a ride because we caught him at his house getting ready to go to work. But I don't remember watching him fly away in a long 1st gear.

[elwesso]

I think he had the JWT ecu... Maybe a JDM ecu.....

[AZ94Q]

A few thoughts

First: We are discussing AFTERMARKET JDM Ecus, not stock JDM ecus, so of course the 112 or whatever limit will be erased.

Second: JWT put serious development into this ECU. I would love to see how it fairs against an aftermarket jdm ecu..

Someone should try to get in contact with one of the companies and find out what the deal is with our cars and compatibility.

[Q45RaCiNg_JR]

Oh... For sure it's not a JWT chip. He never even heard of them. And yes it was a Aftermarket ECU. If I can find his number I'll give him a call and get more info out.

[RMiller]

I know of a person back in Cali who has a JDM Bodykit, Exhuast and a JDM Aftermarket EC...I asked the guy how he likes it. He said " trust me when you don't even have to be in 2nd to beat a Saleen Mustang with Mods, you'll be proud of your Q."

Something doesn't add up here.

[HeavyDuty]

Something doesn't add up here.

Why not? All Saleens, or all Mustangs for that matter are all the same, right?

Sport model (body kit only), S281, S351, they're all slow, it's just a bunch of hype with their S/C, A/C, 450hp 5.8's.

:rolleyes

[QShip]

A few thoughts

First: We are discussing AFTERMARKET JDM Ecus, not stock JDM ecus, so of course the 112 or whatever limit will be erased.

Second: JWT put serious development into this ECU. I would love to see how it fairs against an aftermarket jdm ecu..

Someone should try to get in contact with one of the companies and find out what the deal is with our cars and compatibility.

I've emailed JUN twice about their ecu, but they have not responded.

[Q45tech]

On ecu the only things you can do are change the fuel mixture and change the ignition advance and move VVT engagement/release rpm........you could also change spark duration [not significant]. Spark tip in backoff [for sudden acceleration] and slope of restoration can vary the feel of acceleration a little.

Maximum power for any rpm will occur when the burn process is 67% completed [peak BMEP] at 16-17 degrees after top dead center.

The Engines are dyno tested to create a series of curves that show what it necessary to meet the above depending on rpm and load.

Then various backoffs from optimum are dialed in to factory ecu for safety and long life durability and the ability to function with lower than 110 octane lab gasoline.

These back offs could be as high as 5 degrees and 20% too rich for optimum peak power.

In some ways you are right about power backoffs to match transmissions..........but its never more than 10-15% [part of other fuel safety measures].

Since SAE regs require power to be speced at 68F a +- 5% variation occurs from temperature alone [20F-120F].

99% of the time oem ecu are way way too rich to create peak power because the cooling systems are under designed to save weight and money........after all few people run WOT for more than 30 seconds as that would get you to 140 mph.

Lots of cheaper aftermarket ecu companies [for OBD1] just bump the advance by 3 degrees and lean WOT by 10% THEN dyno the result and call it a day. A few prestige companies actually dyno tuned the ecu and narrowed in on the BEST adjustments.

I have a custom DINAN ecu for the Q45, they were very very aggressive and on ragged edge compared to SAFER JWT ecu, Dinan stopped marketing ecu in 1994........but we are only speaking of a 1.5 degree more agressive curve. Even 93 octane pings in Summer.......terriffic in Cold weather.

There is no magic ecu when you use up the factory safety amounts that's all there is.

On any of these ecu make sure your coolant temp doesn't exceed 194F or you will be in the summer extra safety ignition retard zone! NONE of the aftermarket ecu change this critical safety parameter195F -1.0 degrees200F -2.0 degrees205F -3.0 degrees210F -4.0 degrees215F -5.0 degrees

Plus the fuel gets EVEN richer as the coolant temp rises to try to cool the cylinders from the excessive temps......a double whammy!

Have seen many aftermarket ecu where owners bump the dist [CAS] initial advance beyond 15 degrees TRUE and waste all the extra advance as the knock sensors firing too early.

[rsiwicki]

Man Dennis...you do have all the Q toys. I have never even heard of a Dinan chip for the Q in all my Q mod searches. They must have only sold one or two of them...and you probably have the only Dinan Q chip remaining known to exist. The other one is probably sitting in some junkyard or somebody is driving around with it in there car with pinging sound that won't go away and don't know that they have a Dinan chip.

[Q45tech]

You are probably right in that they sold a total of 5 units, before they sold their entire reprogramming business. They told me they spent a week of dyno time [$5,000 plus burned a dozen prom models to get it right, then a week of city testing each model.....they figured that had at least $25,000 in expenses.

What ever they found back in 1993 is valid today except our gasoline is worse...........luckily after it turned 200,000 miles the combination of ring wear and chain stretch changed the low rpm dynamics [retarded the cams vs crank------later exhaust closing more overlap......] enough to make the pinging go away except above 90F.

I always decrease the intial timing by a degree or 2 in May and restore in October. You get some really bad gasoline on summer road trips.

We have A/B/C ed the JWT/Dinan/stock on a few 90-92 models multiple times not really much feelable difference between JWT and Dinan. After all no human can resolve 10 HP and 30 HP is barely feelable in a heavy car ...........in that 0.3 -0.4 seconds out of 15 is only 2-2.5%........2-3 car lengths is significant however visually or passing a truck.

[AZ94Q]

I'm hoping for 300 flywheel HP (250RWHP) on my 92 with JWT ecu and stillen exhaust. We shall see. JWT said you should get about 28 hp with the ECU and the intake (since the intake is worthless I'm hoping for 20-25 hp with the ecu)

I always think of the VH45DE as a 300hp engine.. Limited for safety and japanese hp limitations.

300 HP330 lb/torque

I am a happy Q owner (for now)

[Q45tech]

305HP/333 lb/ft [+- 3 units] with JWT ECU and a real straight exhaust [not necessarily Stillen].

How about 240-245 HP since stock RWHP ran 215-218 or so........really depends on chain stretch and rings.

[AZ94Q]

305HP/333 lb/ft [+- 3 units] with JWT ECU and a real straight exhaust [not necessarily Stillen].

How about 240-245 HP since stock RWHP ran 215-218 or so........really depends on chain stretch and rings.

I am not sure I understand your response

Your first line seems to indicate my assumptions arn't that off.

Then your second line seems to say I should be happy with 240-245 hp..

Are you saying I should be happy with 240-245 RWHP, or that 305/333 is a reasonable number? Or are you saying 305 is the equivilant before loss off 240-245?

Q45tech,

I have a question for you. I'm getting a 92 with 13,000 original miles.. Should I be worried about the timing chains right away? It has very low miles, but I'm not sure if that means anything in relation to timing chains.. Although cars would seem to age more with miles, as opposed to time..

Disclaimer: yes I know the car LEGITIMATELY only has 13,000 miles

Any thoughts you have on a real low mileage yet old Q45 would be helpfull..

I don't know how potent the stillen exhaust was, I've never seen

If I got your estimate of 305 hp and 333 torque, I would be happy. IF with the mods the cars have I only get around the original HP rating, I will be consulting the best infiniti mechanic I can find and try to get it as close to 300 hp as possible.

[AZ94Q]

My calculations are

250 RWHP 20% drivetrain loss = 300 crank HP

I've heard 22% should be used because of the LSD and something else..

Q45tech, what do you think the drivetrain loss is?

At 22% 250 would equal 305 hp? Is that why you mentioned the 305 hp?

Well only time will see.

What do you think a 13,000 mile 92 Q45a with JWT ECU/Stillen exhaust would get, in terms of RWHP and crank?

[AZ94Q]

since stock RWHP ran 215-218

I also don't understand this..

Are you saying Original (brand new) q45s wouldn't dyno at their advertised HP, of 278?

At best, assuming 22% loss, 218 would be 264 hp or so...

If 278 was correct, stock Qs should have dynod between 220-230 RWHP... I can't possibly imagine them dynoing less then advertised, espically when I consider all the cars I pummeled in my 91, and how much hp they had..

I know that torque is measured and HP Is at best an illusion, but it's an illusion, which can be verified on the dyno.. The VK45DE was dynoed by popular mechanics, and it came out to exactly the crank HP, via the RWHP + loss.. So what gives.

[Q45tech]

But what is the loss , the loss is not a fixed number with a torque convertor. Nor is the loss fixed with varying temperatures or rpm. The loss is not constant as the power varies.

278 x 0.787= 218.8.......the # I use 21.3%278 x 0.22= 61 therefore 278 minus 61=217.There really isn't much correlation between flywheel HP and rear wheel HP .

I really should have used a wider number 210-220 RWHP. Depending on oil , ATF, diff, tires and temperature plus the amount of strap down force- exerting more on the tires and the tires themselves].

Generally as the BMEP declines [with ring wear & lower compression] the power drops.

Dynos are pretty useless in trying to determine exact flywheel power that why I ignore the rules of thumbs.

After all, ALL that counts is rear wheel power - other than fuel consumption and proofing BSFC.

There is a great engine dyno [at an engine builder 40 miles away] and for $5,000 I'll be happy to pull your engine after we make chassis dyno measurements and try to get you some real flywheel measurements.

Notice that the cranking compression is speced at 185 with a 142 minimum this is a 23% variation so in theory the running compression could vary that amount [unlikely] but a passable engine could easily be half that or 240-278 HP........but then again this would show up on power balance [and it does if all cylinders don't read EXACTLY the same drop.

Remember none of our engines are brand new and all have some wear.........an easy way to look is to view the exact vacuum depression for each cylinder and the pressure in the exhaust system for each cylinders pulse/pressure wave.

[rsiwicki]

Dennis...as may know, I am trying to do the impossible...build a 300rwhp Q that is reliable without changing any of the internal engine parts, no turbos, no SC, no NOS. How I am going to do this????...I have not figured that all out yet otherwise there would be other 300rwhp already out there.

So my question is "What do I get when I acheive a reliable 300rwhp other than 300rwhp that will be fast as $hit?" A cookie ?

[MiniMan]

Rob, do the rebuild with me! :P

Corey

[Q45tech]

300 RWHP would equate to 385 Flywheel HP assumming 22% loss in drive train and tires and tire to roller interface.

Only way possible would be to replace [retune] plenum and runners with a custom intake either 8 individual TB and tuned stacks or something custom with a dual 4bbl carb.

385 HP at 7200 rpm is only 280 lb/ft so you retune the runner lengths to this rpm..........shorten them by 17-20% [plus extrude hone their diameters 5-6% larger and design a custom exhaust header to tune at this rpm.Retard [make the ex valve close at 18 instead of 8 degrees after TDC] both the exhaust cams one tooth - 10 degrees more overlap .

The engine won't be driveable at low rpms [in a heavy car] as the torque peak will move up to 5500 rpm.

After all 385/4.494= 85.6 HP per liter.

The newer 4.5 makes 340 HP at a lower rpm with less aggressive cam timimg and still meets emission and low rpm goals.

Q engines are only 25% smaller displacement than NASCAR engines.

[AZ94Q]

300 RWHP would equate to 385 Flywheel HP assumming 22% loss in drive train and tires and tire to roller interface.

I don't understand this..

300 rwhp with 22% drivetrain loss equates to 366 hp.. where is the other 19 hp coming from?

Also, we have seen AGMs headers net 30 PROVEN RWHP. Maybe 300RWHP is a high estimate, but breaking through the 250 RWHP would be no problem, with a set of good headers

270-280 RWHP with headers doesn't seem unreasonable, based on what AGMS car did on the dyno

[HeavyDuty]

I agree with you, AZ, but it's a goofy mathematical thing like calculating gross profit-vs-markup.

If you were to take the 366 x .78 (22%loss) you should have 285.

Whereas if you were to take 385 x .78, you'd get the 300 Tech is talking about.

It's harder to determine crank from wheel. Considering a 22% loss, you'd have to use a factor of 1.285 ( 285 x 1.285) to forward calculate 366 from 285.

Same with 300 to arrive at 385.

It doesn't work backwards & forwards.

A 33% markup only nets a 25% GP.

Aggravating as hell, isn't it?

Oh yeah, headers work.

[rsiwicki]

Okay...here is a wrench to through into things.

I have read on countless other boards that the efficiency loss is not a linear function. In other words, % loss at 200hp is not the same % loss at 400hp and that the % loss decreases as HP increases, in general. So if we have a 280hp=218rwhp and 22% loss then if we modify things to say 380hp=296rwhp using 22% loss...but if there is a nonlinear relationship then 380hp=300rwhp using 21% loss...and if the loss is only 20%, then 380hp=304rwhp.

This makes some sense to me as I am sure that there is a nice curve that would represent the % efficiency loss or gain as the HP changes. Given all the variables involved...I can't imagine that it is a pure linear relationship...something has go to give up more HP to our wheels.

[rsiwicki]

BTW....I did not rule out improving driveline efficiency to get my 300rwhp....I think that carbon fiber driveshaft will add a very nice 10+rwhp. If sijoko can feel a difference after adding heavier and bigger tires, then there must be at least 10+rwhp benefit as you all say that 10rwhp is barely noticeable, but sijoko said he could still feel a nice improvement. Every little bit will add up.

[AZ94Q]

Indeed. It's all about improving efficiency . The level ten and CF driveshaft do this nicely.. I hope this CF not only reduces unsprung weight, but improves the overall reving of the engine.. Like it does on other vehicles I've spoken to owners about.

[HeavyDuty]

I agree with both of those points as well, although to determine the non-linear decreasing percentage for any one vehicle with varying conditions, condition of tune, etc would be extremely complex. Too complex for me, I think 15% is a good rule of thumb on manual trans cars, 20-22% for autos.

Also, my butt-dyno is pretty effecient with respect to 5hp gains, if I know the car.

I'd expect obvious gains with the cf driveshaft.

I'm jealous. :pface