Starting my engine build

[Alex]

Ok lets drop the sciencific terms

In simple words so that everybody can understand:

 

-First of all its not power "pub" bragging bhp theory, its from personal experience.

- Maybe You got it wrong, i did say OEM crank pulley won't stay at one piece.

- Yes you are right its the outer ring of the OEM crank pulley that fails,i never said the actual crank will break

- If you aim for high power/8K+ revs you should go for a boost logic pulley. Otherwise you just wait for trouble to happen.

 

OEM Pulley is in two pieces and it comes apart because its made from a rubber material as Martin said. The outer part of the OEM crank pulley will break and come apart

 

Is this a brand new item or one that's done 100,000miles already?

 

As Martin said very correctly OEM crank pulley is rated for 50% more power.

Interesting...so where is this rating documented...I'd be surprised if it is documented by Toyota when it's about revs and accessory load....which means that it would be 50% more revs not power that would be critical. 10,500rpm....

 

I never said the "crank" will fail. Crank may fail if you get an Unorthodox pulley which is all one piece but I can't say about this for sure as I haven't experienced it myself. My crank has always been very good.

 

Chris:

"Considerable inertia is part and parcel of this, reduce it at your engines peril. IMO if you are hell bent on fiddling with this you might as well remove the thing altogether, enjoy a lot less inertia, and buy in a few cranks and say a few prayers."

 

Who said about failing cranks?

 

As you seem to be banging on about failing cranks. It was mentioned as that is the reason for having the TUNED stock damper...it stops the crank wobbling and destroying itself....so removing it and fitting an untuned one will put more stress on the crank and potentially lead to disaster.

[JamieP]

Just a word of advice, DEFINATELY DON'T keep that OEM crank pulley you got, anything above 700bhp will kill it for a laugh at no time.Get a boost logic one..

 

Thanks for the concern but i am sticking with OEM crank pulley, also im only running itro 500/600 bhp with the gt4088 turbo.

[lockys96]

why jamie, ure king of boost

 

crank her up

[fastisnice]

Is this a brand new item or one that's done 100,000miles already?

 

- Why don't you try it out and tell us since you know everything?

Do you have a PHD in engineering? i will be surpsrised if you dont

 

Interesting...so where is this rating documented...I'd be surprised if it is documented by Toyota when it's about revs and accessory load....which means that it would be 50% more revs not power that would be critical. 10,500rpm....

 

???????????????

So unless members in here have documented evidence from toyota shouldn't really belong to this club?or say their opinion

 

As you seem to be banging on about failing cranks. It was mentioned as that is the reason for having the TUNED stock damper...it stops the crank wobbling and destroying itself....so removing it and fitting an untuned one will put more stress on the crank and potentially lead to disaster.

 

[color="Blue..............did I bang on the phrase failing crank:Pling: ? I think you don't read who posts what?Do you just speak random now? Chris spoke about failing cranks. All i said about was my personal exp on the OEM crank pulley, unless it bothered you I spoke of "real" power?

[/color]

[Digsy]

As should all know by now I'm a steadfast supporter of the stock crank pulley, not only for its torsional damper (the one that nearly everyone has got their head around now) but also for its bending damper (the equally important one that everyone forgets).

 

I've done this to death in the past but for a very quick summary, the engine cycle puts energy inputs into the crank which get resisted by the drivetrain (most importantly, the flywheel). The crank acts like a big watchspring and whangs back and forth, "nudging" its way around a complete revolution rather than revolving smoothly. The torsional damper on the front of the crank attempts to cancel out these vibrations.

 

Usually the argment goes song the lines of swapping out the stock pulley on a BPU or near stock engine. The flipside of the coin is what would happen if you kept the stock damper but significantly changed tne engine - that's what has come up here.

 

The vibration input-the thing that starts it all off-is the cylinder firing (as well as all the other of the four strokes). If you significantly change the firing pressure then you will change the torsional vibrations, which will put the damper out of tune. By how much is almost impossible to tell without sophisticated analysis.

 

I'm struggling to see how this would fail the pulley, however. As mentioned already by Chris, the centrifugal and inertial effects of producing more power (even by revving a bit higher) will be negligible. The FEAD will be transmitting a bit more torque because the drive curves for the water pump and alternator will rise with increased engine speed. This is also true for the PAS pump and AC, but only when on lock and clutched in, respectively. I reckon this is also negligible.

 

I suppose it is feasible that you could hit some kind of odd resonance issue with the stock damper that happens to coincide with a cylinder pressure that just happens to produce 700bhp, but I'd hesitate to say that its the power is the root cause of the problem. I'd tend to say that the increased cylinder pressure might be making something happen to the cranktrain which is destroying the TV damper. My guess would be increased torsional vibration because of the bigger input forces.

 

The only way the TVD or FEAD belt "sees" the engine power is through torsionals. The FEAD system is just a parasititc loss bolted to the front of the engine. As long as the belt is under control then you should be able to drive it no matter what power the engine puts out.

 

I've done some FEAD development inconjuction with Gates and AFAIK engine power isn't an input into the equation - but torsional vibration is.

 

In conclusion, maybe there is something that happens to the cranktrain, by coincidence at about 700hp. Maybe the torsionals get so bad that the pulley itself goes into resonance and fails. Maybe the same effect also oevrcoems teh stock FEAD tensioner damper and flings the belt off, but don't forget that the FEAD only sees what the crank is doing, so my primary concern would still be with the crankshaft.

 

Use it as an axcuse to replace with a solid pulley if you want but I can only see that making things worse for the crankshaft.

[Alex]

fastisnice's last post

 

 

As has been said 2 or 3 times already the damper is NOT affected by POWER directly.

 

No I don't have a PhD but thanks for the compliment.

 

Look YOU came onto this thread and said - and I'm paraphrasing "use the ATI/BL Crank Pulley cause it's the bestest eva, innit"

 

I was asking YOU for reasons why we should accept your point of view, it's not a trick question, I'm simply trying to ascertain if you have an actual proven reason or just some bad luck with old bits of kit.

 

This rule that Martin came up with that the pulley can take 50% more of something than stock also needs clarifying...ie what was the source of this information.

 

I'm trying to stop the proliferation of Internet Rumours and Dis-information with some decent well argumented reasons.

 

I have no interest persay as to which is better (the ATI/BL or the OEM damper) but I do want to know why one is better than the other.

 

If you cannot answer this simple question hold your hands up and say so...don't keep running on about the same already discredited/flawed arguments.

[Alex]

And whilst I typed that I think Digsy cleared it all up

[fastisnice]

"The only way the TVD or FEAD belt "sees" the engine power is through torsionals. The FEAD system is just a parasititc loss bolted to the front of the engine. As long as the belt is under control then you should be able to drive it no matter what power the engine puts out."

 

I can drive it fine, belt jumps ONLY under high boost when I hit hard the rev limiter (@8K revs) few times.

[fastisnice]

"I have no interest persay as to which is better (the ATL/BL or the OEM damper) but I do want to know why one is better than the other."

 

I have seen 3 other high bhp supras breaking the "outter ring" crank pulley. Now I don't know if this is just coincidence but its not a hoax!!. It happens

 

PS Im not a trader or a boost logic dealer, i never said its the best or actually give a shit if its the best. Works for me!

 

 

This taken out of boost logic's website

"

Boost Logic's SFI Approved Crank Damper

 

We use these Crank Pulley's on our 1000hp 2JZGTE cars. These also fit the NA 2JZGE with no problems. The stock harmonic dampener cracks because the stock hub is made out of aluminum. We fixed this problem by making the hub out of steel. This CNC'd unit, unlike the stock one, will NEVER crack. The outer pulley is made of lightweight aluminum. What's even better is that it is SFI approved, fully dampened, and is lighter than stock. The stock unit weighs in at 7.25lbs while this unit weighs 5.75lbs; a 20.68% reduction of rotating mass. The best part is that it also uses the STOCK belt while other SFI approved dampeners require a different, $50 belt, on top of the cost of the damper.

 

Steel Hub to prevent cracking like the stock aluminum hub

Press Fit Hub to alleviate keyway gouging

20.68% weight reduction in rotating mass

Inertia weight dampening

SFI 18.1 Approved

Allows the use of the stock belt

Tested and used on cars producing well over 1000 Rear Wheel Horsepower

"

[Gamer]

Just for info the BL and ATI dampeners are both dampened only they go about it differently. The BL damper uses an inertia weight type damper setup. The weight inside the damper moves.

 

The ATI damper uses rubber elastomers which is a different type of damper system.

 

Both the ATI and BL dampeners are SFI approved. Meaning that they have been tested to SFI Specification #18.1

 

This specification is enforced by most racing sanctioning bodies to assure that the dampers conform to specified standards. While the SFI test is quite stringent and requires the damper to be spin tested at a speed of 12,000 rpm for a period of one hour.

 

http://www.sfifoundation.com/

[Chris Wilson]

Ah, the belt comes off when you hit the rev limiter does it? Try softening the rev cut by bringing it in over a longer RPM band, or whatever your ecu allows. The torsions from hitting some of the more crude rev limiters can excite things a lot. Why is it hitting the rev limiter anyway? To me they are an emergency fail safe, not something you want to even know exists unless you make a driving error or something amiss happens with the throttle control system or drivetrain, or maybe, just perhaps, traction problems occur under poor conditions.

[Digsy]

Just for info the BL and ATI dampeners are both dampened only they go about it differently. The BL damper uses an inertia weight type damper setup. The weight inside the damper moves.

 

The ATI damper uses rubber elastomers which is a different type of damper system.

 

Both the ATI and BL dampeners are SFI approved. Meaning that they have been tested to SFI Specification #18.1

 

This specification is enforced by most racing sanctioning bodies to assure that the dampers conform to specified standards. While the SFI test is quite stringent and requires the damper to be spin tested at a speed of 12,000 rpm for a period of one hour.

 

http://www.sfifoundation.com/

 

From what I've read on the 'net the SFI 18.1 spec looks like just a burst test (to prove that it won't fly apart and exit the engine ebay through the botten and take someone's head off on the way). It doesn't prove that it is or isn't a more or less suitable part than the stock item.

 

Yes, it appears to have a torsional element, and steel hub. I must say that all of the TVD failures I've read about on here have been down to de-lamination of the rubber and nor cracking of the hub, though. How they have managed to give it the same inertia mass characteristics as the stock part with less inertia remains a mystery. I think they used to have some vibration plots on their site last time I looked. Can't find them now.

 

Anyway, I'm not pro or anti BL or ATI or anyone. I'd just like to understand the root cause of a problem before bolting on a part that could very well move the issue somewhere else.

 

FWIW none of the aftermarket dampers I've seen have a bending element like the stock part.

[Gamer]

I don't know if this helps or not but here is a picture of the inside of the BL pulley taken from Supraforums.

[Miguel]

Anyone know of a 2jz Crank that has failed from fatigue caused by Incorrect dampening ( including lightened flywheels) and how many known failures ?

[fastisnice]

Ah, the belt comes off when you hit the rev limiter does it? Try softening the rev cut by bringing it in over a longer RPM band, or whatever your ecu allows. The torsions from hitting some of the more crude rev limiters can excite things a lot. Why is it hitting the rev limiter anyway? To me they are an emergency fail safe, not something you want to even know exists unless you make a driving error or something amiss happens with the throttle control system or drivetrain, or maybe, just perhaps, traction problems occur under poor conditions.

 

 

hmm, yeh you could be quite right, im using motech, Owen mapped to hit the rev limiter at 8K. I was just messing around hitting hard the rev limiter just to chuck out flames (I told them so when they mapped the car) but I can tell them to "soften" the rev limiter? so that when it hits, takes longer - more revs say 100 revs longer? is this correct? (So maybe this will stop the belt coming off).

[Chris Wilson]

hmm, yeh you could be quite right, im using motech, Owen mapped to hit the rev limiter at 8K. I was just messing around hitting hard the rev limiter just to chuck out flames (I told them so when they mapped the car) but I can tell them to "soften" the rev limiter? so that when it hits, takes longer - more revs say 100 revs longer? is this correct? (So maybe this will stop the belt coming off).

 

I would ceratinly try this, if you want post up these settings from your current map, in the screenshot linked below, and I'll look at it for you:

 

http://www.gatesgarth.com/motec.jpg

[JamieP]

Thanks for the advice and im sticking with OEM damper, can any more talk of crank dampers please be taken to technical please:)

few pics from today.

 

 

 

[Muffleman]

[supragold]

Oh mate thats looking awesome. I love it. Good work fella.

[Tom]

Nice, that red is bright eh?

[b_have]

hmm, yeh you could be quite right, im using motech, Owen mapped to hit the rev limiter at 8K. I was just messing around hitting hard the rev limiter just to chuck out flames (I told them so when they mapped the car) but I can tell them to "soften" the rev limiter? so that when it hits, takes longer - more revs say 100 revs longer? is this correct? (So maybe this will stop the belt coming off).

 

A softened limiter would knock individual cylinders out progressively (sounding like RLTC).

[JamieP]

Cheers guys... the red is a bit bright but its the only high temp red i could get... looks better in real... the flash makes it look brighter;)

Im so happy with how this is going:cool:

[supragold]

Im so happy with how this is going:cool:

 

I bet you are mate.

[Graham S]

Dude that is a seriously clean engine, i'm so so jealous! Got any spare jobs going that pay as much as what you must be on!!

 

Love the painted block with the new clean silver, looks amazing. You sure your only running about 600 hp? That must be a quite low boost?

[Alex]

LOL the Silver Sup in the background...is the numberplate a sign of the reason it's there??!!

 

Engine looks fab