NICO ECU RPM Redline Question

[Infinitiguy19]

I read in one of the million Q45tech Posts that if the Redline limit was 7500 RPM's the Transmission would shift better or I think it was stay in first gear going down the track there by improving the Qtr mile time significantly because of a 2 second or mili second less of a shift.

Does that really make a difference I mean its only 100 RPM's?

Would an extra 100 RPM's harm the engine?

[qsiguy]

First of all, in my experience, in 'D' mode it will shift based on the TCU's settings, so it will still shift around 6700-6900 RPM. You have to use the gated shifter to use the new redline.

One advantage I found with mine is that when you allow it to shift above 7k from first to second gear you start second gear at a higher RPM and there is less delay before you are screaming in 2nd. Same with 2nd to 3rd. You keep the RPM's in a higher power band shifting at a higher RPM. With a higher redline in 2nd gear you might be able to stay in 2nd through the 1/4 mile and avoid the shifting lag. I'm not sure if you can stay in 2nd through the 1/4 mile but that would be the main advantage I can see. I personally can't stay in 2nd through the 1/4 mile because I have the 4.08 rear diff now and hit the redline much earlier.

Any redline, even the OEM redline, has the potential to harm the engine. If your motor is properly maintained it should be able to handle the higher redline just fine.

[maxnix]

I think it is 7400 rpm on the NICO.

[Infinitiguy19]

Ok if you shift while NOT letting off the gas pedal does that do any damage to the transmission? (From what I read it does)

Does "Any redline, even the OEM redline, has the potential to harm the engine. If your motor is properly maintained it should be able to handle the higher redline just fine." This apply to the transmission as well?

I was Cleaning out the motor on day (I held it in first to the redline which looked like 7000 RPM's) (Don't know if the Tachometer should be trusted though) And the car felt like it wanted to shut off on me is that normal or should it just have bounced up and down on the Tachometer just like Honda's?

Brian I know its 7400 on the NICO ECU but I was wondering if Wes Bumps it up to 7500 RPM's would that make a difference or just hurt the motor?

C'mon Denis or Wes I could really use your help right about now.

[MinisterofDOOM]

I recorded this a couple days ago. 0 to ~70 with NICO stage II. This was done in "D" without manual shifting. I was not pushing the car as hard as it would go, but still pretty hard.http://www.youtube.com/watch?v=Uu_7PGTIel4

And I've since addressed the brake light (fluid needed topping off) and washer fluid (you can barely see the notification on the right).

[Infinitiguy19]

Not bad, But you have a switcher right, Think you could make a video of the different programs?

[Q45tech]

TCU uses speed of driveshaft [MPH] to control shifts not rpm.

Notice all graphs in FSM are in MPH [KMH" not RPM.

Why so many have so many problems when substituting TCU.

94-96 TCU have the values corrected [MPH] for 1st and 2nd gear changes [5%].

If members plan to quote me or infer that I said something PLEASE GET THE NUMBERS CORRECT as others will get confused by your quote errors!!

To my knowledge I have never typed 7500 rpm in any of my 12,000 posts

[Infinitiguy19]

Sorry about not getting everything right but I just couldn't search for what i found just too much.

So there is no need for 7500 RPM limit 7400 RPM limit is just fine?

If I wanted to go to 7500 RPM limit would there be any more risk than 7400 RPM limit?

What about when the car almost or felt like it wanted to shut off on me when i was in first gear trying to clean out the carbon in the engine is that normal or not?

[Q45tech]

The limit is 7300 rpm, a number derived by the stroke length, the weight of piston, pin, rod, and bolts plus some knowledge of strength of materials of the cap bolts.

The first two companies to reprogram ecu [Dinan and JWT] knew from prior Nissan design history that Nissan always leaves a 10% reserve but decided to use up only 6% to protect their own reputation.

6900 x 1.06= ~7314 rpm.........................I'm almost positive a brand new properly broken in engine could survive the full 10% [7590 rpm] for a few seconds for a few times. But not the 270,000 miles since I've had a 7300 rpm hard limit.

It is really a matter of trust between you and previous owners [concerning oil changes] and the Japanese engine technican who hand assembled and torqued every rod cap bolt..............Either one can create a very noisey situation.

[Infinitiguy19]

WOW Thanks for the response and the easy to understand RPM limit.

But "6900 x 1.06= ~7314 rpm" What is the 1.06?

So 7400 is the most and safest limit for all VH45 engines?

Wes says you can get the MAX RPM limit to 8000 if you add better cams, But the lower end can take 8000 RPM's stock. Is that true?

[Rex]

What about when the car almost or felt like it wanted to shut off on me when i was in first gear trying to clean out the carbon in the engine is that normal or not?

Are you saying you were holding it against the RPM redline and the the fuel cut off started making the car feel like it was shutting off?

[Infinitiguy19]

Not really because I had a bad FPCU that only had stage 1-2 and no 3, Every time I gave the car full throttle with the bad FPCU the car would go back and fourth like a kid driving a 5 speed. (The car would just jump)

[Q45tech]

The engine depending on year was designed to shift at 6500 rpm since HP peaked at 5500 and 6,000 rpm depending on outside air temp [as the Helmoltz Tuning varies with temperature]. THe VE starts to seriously fall after 6500 rpms...................as the torque is already down by 50 lb/ft at 6,000 [245 x (6,000/5252) =~ 277 HP]..................based on memory of some dyno runs by 6500 rpm torque is doen by another 25 to 220 lb/ft......................by 7300 rpm the torue is around 160 lb/ft and just 220 HP

The only reason the 7300 rpm helps in quarter mile [or a run to 150 mph] is that it allows 98.5 mph before limiter avoiding a shift at 93 mph with 6900 limit.

Some acceleration near the end of quarter mile is better than absolutely NONE during and just after a forced shift.............that last 0.8 seconds [100 feet] is valuable if you are showing a quarter mile slip..........the difference between a 14.8/96 and a 15.2/93.

[Q451990]

But "6900 x 1.06= ~7314 rpm" What is the 1.06?

That is adding the 6% he mentioned to the stock rev limiter.

Heath

[Infinitiguy19]

Wow that what I was looking for thanks.

I barley understood Q45Techs second post but, Nealy a year ago I would have been confused after the first line.

[Q45tech]

My Math is all adding> dividing and at worse a little trig, geometry, ,roots and exponentials.College starts with 4 courses in Math above Calculus I to do well in engineering.

1. An internal combustion engine connecting rod is designed with bolts having a minimum required strength. A strength safety factor Sfa is calculated based on an axial strength limit load FX of the bolt and the maximum load FB to be born by the bolt due to a piston inertia force (Sfa=FX/FB) acting on the connecting rod. A mating surface separation safety factor Sfb is calculated based on the tensile load (FB−FC) resulting from the piston inertia force and the load FE carried by the bolts at a mating surface separation limit, i.e., the maximum bolt load FE at which the connecting rod main body and the cap remain in contact without separating (Sfb=FE/(FB−FC)). The mating surface separation safety factor Sfb of the connecting rod is set to be equal to or larger than the strength safety factor Sfa of the bolts (Sfb≧Sfa).

http://epubl.luth.se/1402-1617...E.pdf

7300 rpms with a 3.256" stroke results in a piston speed of 66 feet per second or 66 x60= 3960 feet per minute

http://www-rcf.usc.edu/~sangta...m.pdf

Light [soft] valve springs are used to limit cam wear and friction [stress on chain drive] so to avoid valve float things must be upgraded when you increase rev limit.

Thankfully springs/valves begin to float before rod bolts and rod fail in NA situations.

[qsiguy]

...Wes says you can get the MAX RPM limit to 8000 if you add better cams, But the lower end can take 8000 RPM's stock. Is that true?

Ship me your ECU and I'll bump up your rev limiter to 8K and you can be the guinea pig!

FYI, with my boost I actually dropped my rev limiter back down to OEM spec. Didn't do to well above 7K under boost. Pre turbo I liked taking it up to 7.3K.

Interesting info regarding the TCU shifting at speed, not RPM. That would explain why mine shifts at a little higher RPM in 'D' with the 4.08 than with the stock rear diff. Certainly it changes that based on engine load as well because it does not always shift at the same speed?

[Infinitiguy19]

Yea I will have to pass on that, Because I love my car.

If I send the ECU to you can you do a NICO ECU???

Or how much to bump it to 7400 RPM's?

[Q45tech]

Hopefully your abuse by running lean due to FPCU partial failure won't have done enough heat damage to total destroy it quickly with a raised limit.

Changing limits are for new engines not those that you don't know every mile [unless you have examined the bearings and internal.

Sure the ECU mods work on old high mile engines, but that just proves the amount of safety reserve builtin.

[Infinitiguy19]

Hopefully your abuse by running lean due to FPCU partial failure won't have done enough heat damage to total destroy it quickly with a raised limit.

What do you mean by that?

My FPCU is fine, The new one I got which is not installed is broken.

[qsiguy]

...If I send the ECU to you can you do a NICO ECU???...

Yes, but you need to go through Wes. We are working together.

[Infinitiguy19]

Aww was hoping to get a deal. Just kidding

No way to go though you because Wes is WAY to busy?

[elwesso]

I already said we're not doing the 8 program ECU's, especially until we get the 94 ECU's up and running!!! You can get whatever you want whenever you want, im best reached through email!

I've tried my hardest to help you out, im not sure what else im supposed to do?

[Infinitiguy19]

I already said we're not doing the 8 program ECU's, especially until we get the 94 ECU's up and running!!! You can get whatever you want whenever you want, im best reached through email!

I've tried my hardest to help you out, im not sure what else im supposed to do?

I never mentioned anything of that sort nor did I think about it when posting I finally came to my senses and realize that stage 3 and stock is the way to go.

I emailed you pics for the Q45.org main page and I know the quality wasn't the best but I never received an answer from you.

Plus I am getting a 91 Q45 With a 91 ECU with TCS.

[Kiven422]

If you have an extra ECU lying around you should just get Stage 2 & 3 since you will have the stock option available.

I read somewhere that the 90-93 ECUs don't fully control the fan on the 94Q? Does it turn the fan on at all? or does it just stay off or run forever?

[maxnix]

The earlier ECU only have auxiliary cooling fan off or on, whereas the newer 16 bit ECU have two speeds on besides off.

[elwesso]

actually 90-93 ECU cant control the fan, however unless your cooling system is seriously compromised then you dont need to worry... 90-93 are controlled the old school way with a temp switch

Reason I say that is because chances are whenever its hot enough for a car to get hot enough on a good cooling system chances are your AC is on, which will turn the fan on WAY before the ECU is gonna turn it on... With the AC off with my stock 94 ECU ive NEVER had the aux fan come on even on the hottest days idling.

NICO ECU's are only for those cars that are in tip top operation, and they will cause NO ISSUES on said cars.

[Kiven422]

Ahh I see. The A/C will turn the fan on. I really don't use A/C, even on the hottest days unless I have girls or a lil b**ch in the car. But its good to know I can still turn that fan on because traffic can easily overheat an engine on hot days.

[qsiguy]

I've heard about the cooling fan not working with <93 ECU's on >94 models but my fan will kick on when the temp is high and the A/C is not on. I don't have an explanation. I have a '94 with a '93 ECU.

[maxnix]

Yeah, I thought Q45tech said the early ECU had a simple on/off signal. But who knows?