Jump to content
SAU Community

RB26Dett lightweight Font Pulley experiment

rev210

By rev210,
in Engines & Forced Induction

 Share

Recommended Posts

rev210 Grand Master

rev210

Posted
Posted

I've decided to use my GTR's engine as a guinea pig for a light weight alloy front pulley.

In a few months a mate is going to have two Rb26 long motors from which we will use the front pulley to have a copy made in lightweight alloy.

It is my belief that the 'harmonic' issue people have suggested is not an issue at all for an engine that will see less than 8,000rpm , is a street motor with less than 600hp , and will only ever occasionally see a drag strip appart from regular road driving. To date the only evidence given of a front pulley having conection with harmonic block cracking is the reports from the early group A days when the front balancer was re-designed. My optimistic take on this is that the regular factory rb26 crank needs work in the counterweight area to address the sustained high rpm use. Seems there are a few factorys making upgraded cranks for this reason. Attempting to externally balance the engine is a bandaid.

Since my engine is over 230,000kms old if there are any 'harmonic' issues I expect it will show up rather quickly.

Anyway I'm happy to continue the debate and provide a real working example.

Fitzpatrick Speed Works Mentor

Fitzpatrick Speed Works

Posted
Posted

the harmonic balancer is balanced in con-junction with you crank... its weight is vital to your crank shaft being balanced over the main journals and big ends having a lighter one will throw this out and probably throw a rod through the block as well!!!! THere are no harmonic imbalances in a rb26!!! The haromonic balancer is also a dampner and the reason it is often steel is due to its better resenence frequency as opposed to alloy!!! You cannot internally balance a crank on its own as there will always be the flywheel and clutch hanging off one end. the balancer also is there to counterweight these!!! I would talk to an engine builder not just a mechanic before you decide to do this!!! Hope this sheads some light on the problems associated with this!!!

Cheers, Daniel.

rev210 Grand Master

rev210

Posted
  • Author
Posted
the harmonic balancer is balanced in con-junction with you crank... its weight is vital to your crank shaft being balanced over the main journals and big ends having a lighter one will throw this out and probably throw a rod through the block as well!!!! THere are no harmonic imbalances in a rb26!!! The haromonic balancer is also a dampner and the reason it is often steel is due to its better resenence frequency as opposed to alloy!!! You cannot internally balance a crank on its own as there will always be the flywheel and clutch hanging off one end. the balancer also is there to counterweight these!!! I would talk to an engine builder not just a mechanic before you decide to do this!!! Hope this sheads some light on the problems associated with this!!!

Cheers, Daniel.

daniel,

It's not a harmonic balancer. It has a tortional vibration function not a balancing function, very different things. your on the wrong track.

Look at the description of the crank pulley in the GTR manual. There is a fair bit covered in a previous thread on this issue.

http://www.skylinesaustralia.com/forums/sh...ighlight=pulley

Thanks for your input none the less.

Did I say 230,000kms?

I meant 237,000kms. Engine runs very well for a grandpa and thats testimony to a good service history. Oh, it has had a full life too with track days and hill climbs and things.

Fitzpatrick Speed Works Mentor

Fitzpatrick Speed Works

Posted
Posted

rev i have been led to believe that the so called balancer issues in the early group a's were to do with no.1 cank main journal issues on a batch of n1 engines!!!

I cant get that thread to open, can everybody else if not maybe Prank can see if its bugged!!! I believe you can reduce the mass by a degree but i would be scared of cutting the weight in half and using a very non conductive and non acoustic metal such as alloy!!! Also the stock harmonic balancer isnt just a chunk of metal it is actually cleverly designed, i know i shouldnt say the factory wouldnt have done it like this if they could do it better cause that is such an unrelated comment for so many other things but the harmonics of a crank is a very detailed thing.. an un-related example you jsut dont change the main journal size cause you think it can be done different or better, these are the areas where all the research hours go when creating an engine...and its the same for dampening they spend many hours trying to get the engine smooth and vibration free through r&d on thinks like the balancer(Sorry to call it that even though the crank is what is balanced) But again you have your reasons i have mine just adding to the discussion!!!!

rev210 Grand Master

rev210

Posted
  • Author
Posted
rev i have been led to believe that the  so called balancer issues in the early group a's were to do with no.1 cank main journal issues on a batch of n1 engines!!!

I cant get that thread to open, can everybody else if not maybe Prank can see if its bugged!!! I believe you can reduce the mass by a degree but i would be scared of cutting the weight in half and using a very non conductive and non acoustic metal such as alloy!!! Also the stock harmonic balancer isnt just a chunk of metal it is actually cleverly designed, i know i shouldnt say the factory wouldnt have done it like this if they could do it better cause that is such an unrelated comment for so many other things but the harmonics of a crank is a very detailed thing.. an un-related example you jsut dont change the main journal size cause you think it can be done different or better, these are the areas where all the research hours go when creating an engine...and its the same for dampening they spend many hours trying to get the engine smooth and vibration free through r&d on thinks like the balancer(Sorry to call it that even though the crank is what is balanced) But again you have your reasons i have mine just adding to the discussion!!!!

It's all good I'm very happy to have the input. And of course I need plenty of people to say 'I told you so' when it doesn't work :)

rev210 Grand Master

rev210

Posted
  • Author
Posted

Something from the thread I mentioned for those who can't open it...

I think we are getting the pulleys confused with the harmonic dampers found on some V6 / V8 engines. "Harmonic Balancer" is a term that is used loosely in the automotive industry. Technically, this type of device does not exist. The "balancer" part comes from engines that are externally balanced and have a counterweight cast into the damper, hence the merging of the two terms. None of the applications that we are talking about utilize a counterweight as part of the pulley as these engines are internally balanced.

The pulleys on most of the new import and smaller domestic engines have an elastomer (rubber ring) incorporated into the pulley that looks similar to a harmonic damper. The elastomer in the OEM pulley serves as an isolator, which is there to suppress natural vibration and noise from the engine itself, the A/C compressor, P/S pump, and alternator. This is what the manufacturers call NVH (Noise Vibration & Harshness) when referring to noticeable noise and vibration in the passenger compartment. It is important to note that in these applications, this elastomer is somewhat inadequate in size, as well as life span, to act as an effective torsional damper. If you look at the pulleys on some of the imports there is no rubber to be found at all. Most who have installed and driven a vehicle with pulleys will notice the engine actually feels smoother. This is a natural result of replacing the heavy steel crank pulley with a CNC-machined aluminum pulley. NVH is variable and unique to every car. NVH will increase with the installation of an aftermarket intake and/or exhaust, for example. Think of OEM intake systems in newer cars, they use baffles and resonators in the intake to quiet all the intake noise. Aftermarket intakes eliminate these resonators and create dramatic increases in engine noise from the throttle opening and closing. So to most tuners, certain types of NVH can make the driving experience more enjoyable.

The purpose of a traditional harmonic damper is to protect against crank failure from torsional movement. This is not necessary in most modern engines because of the many advances in engine design and materials. Factors such as stroke, displacement, inline, V configurations, power output, etc., do determine when and how these harmonics and torsional movements occur.

Again, there is a lot of internet hearsay about the pulleys. When motor failures occur, too often people are quick to blame the pulley first, rather than taking the time to look logically into why there was a problem.

Here's a few examples of successful front pulley change overs on 6 cyl:

BMW M series , 5 series, Audi A6 ,Toyota the whole range of 6's found in supras including NA's and turbo's. This is a small sample of the straight 6's that can live without the harmonic balancer. All have had the front pulley replacement and none have had premature bearing failure as a direct result.

Food for thought.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Duncan
      Neil's R33 Gts-t Build

      By Duncan · Posted

      OK, so again it has been a bit of a break but it was around researching what had been done since I didn't have access to Neil's records and not everything is obvious without pulling stuff apart. Happily the guy who assembled the engine had kept reasonable records, so we now know the final spec is: Bottom end: Standard block and crank Ross 86.5mm forgies, 9:1 compression Spool forged rods Standard main bolts Oil pump Spool billet gears in standard housing Aeroflow extended and baffled sump Head Freshly rebuilt standard head with new 80lb valve springs Mild porting/port match Head oil feed restrictor VCT disabled Tighe 805C reground cams (255 duration, 8.93 lift)  Adjustable cam gears on inlet/exhaust Standard head bolts, gasket not confirmed but assumed MLS External 555cc Nismo injectors Z32 AFM Bosch 023 Intank fuel pump Garret 2871 (factory housings and manifold) Hypertune FFP plenum with standard throttle   Time to book in a trip to Unigroup
    • PranK
      My BMW E39 528i touring

      By PranK · Posted

      I forgot about my shiny new plates!
    • PranK
      My BMW E39 528i touring

      By PranK · Posted

      Well, apparently they do fit, however this wont be a problem if not because the car will be stationary while i do the suspension work. I was just going to use the 16's to roll the old girl around if I needed to. I just need to get the E90 back on the road first. Yes! I'm a believer! 🙌 So, I contacted them because the site kinda sucks and I was really confused about what I'd need. They put together a package for me and because I was spraying all the seat surfaces and not doing spot fixes I decided not to send them a headrest to colour match, I just used their colour on file (and it was spot on).  I got some heavy duty cleaner, 1L of colour, a small bottle of dye hardener and a small bottle of the dye top coat. I also got a spray gun as I needed a larger nozzle than the gun I had and it was only $40 extra. From memory the total was ~$450 ish. Its not cheap but the result is awesome. They did add repair bits and pieces to the quote originally and the cost came down significantly when I said I didn't need any repair products. I did it over a weekend. The only issues I had were my own; I forgot to mix the hardener into the dye two coats but I had enough dye for 2 more coats with the hardener. I also just used up all the dye because why not and i rushed the last coat which gave me some runs. Thankfully the runs are under the headrests. The gun pattern wasn't great, very round and would have been better if it was a line. It made it a little tricky to get consistent coverage and I think having done the extra coats probably helped conceal any coverage issues. I contacted them again a few months later so I could get our X5 done (who the f**k thought white leather was a good idea for a family car?!) and they said they had some training to do in Sydney and I could get a reduced rate on the leather fix in the X5 if I let them demo their product on our car. So I agreed. When I took Bec in the E39 to pick it up, I showed them the job I'd done in my car and they were all (students included) really impressed. Note that they said the runs I created could be fixed easily at the time with a brush or an air compressor gun. So, now with the two cars done I can absolutely recommend Colourlock.  I'll take pics of both interiors and create a new thread.
    • GTSBoy
      R33 Fuel Pump & Brakes after alarm swap

      By GTSBoy · Posted

      Power is fed to the ECU when the ignition switch is switched to IGN, at terminal 58. That same wire also connects to the ECCS relay to provide both the coil power and the contact side. When the ECU sees power at 58 it switches 16 to earth, which pulls the ECCS relay on, which feeds main power into the ECU and also to a bunch of other things. None of this is directly involved in the fuel pump - it just has to happen first. The ECU will pull terminal 18 to earth when it wants the fuel pump to run. This allows the fuel pump relay to pull in, which switches power on into the rest of the fuel pump control equipment. The fuel pump control regulator is controlled from terminal 104 on the ECU and is switched high or low depending on whether the ECU thinks the pump needs to run high or low. (I don't know which way around that is, and it really doesn't matter right now). The fuel pump control reg is really just a resistor that controls how the power through the pump goes to earth. Either straight to earth, or via the resistor. This part doesn't matter much to us today. The power to the fuel pump relay comes from one of the switched wires from the IGN switch and fusebox that is not shown off to the left of this page. That power runs the fuel pump relay coil and a number of other engine peripherals. Those peripherals don't really matter. All that matters is that there should be power available at the relay when the key is in the right position. At least - I think it's switched. If it's not switched, then power will be there all the time. Either way, if you don't have power there when you need it (ie, key on) then it won't work. The input-output switching side of the relay gains its power from a line similar (but not the same as) the one that feeds the ECU. SO I presume that is switched. Again, if there is not power there when you need it, then you have to look upstream. And... the upshot of all that? There is no "ground" at the fuel pump relay. Where you say: and say that pin 1 Black/Pink is ground, that is not true. The ECU trigger is AF73, is black/pink, and is the "ground". When the ECU says it is. The Blue/White wire is the "constant" 12V to power the relay's coil. And when I say "constant", I mean it may well only be on when the key is on. As I said above. So, when the ECU says not to be running the pump (which is any time after about 3s of switching on, with no crank signal or engine speed yet), then you should see 12V at both 1 and 2. Because the 12V will be all the way up to the ECU terminal 18, waiting to be switched to ground. When the ECU switches the fuel pump on, then AF73 should go to ~0V, having been switched to ground and the voltage drop now occurring over the relay coil. 3 & 5 are easy. 5 is the other "constant" 12V, that may or may not be constant but will very much want to be there when the key is on. Same as above. 3 goes to the pump. There should never be 12V visible at 3 unless the relay is pulled in. As to where the immobiliser might have been spliced into all this.... It will either have to be on wire AF70 or AF71, whichever is most accessible near the alarm. Given that all those wires run from the engine bay fusebox or the ECU, via the driver's area to the rear of the car, it could really be either. AF70 will be the same colour from the appropriate fuse all the way to the pump. If it has been cut and is dangling, you should be able to see that  in that area somewhere. Same with AF71.   You really should be able to force the pump to run. Just jump 12V onto AF72 and it should go. That will prove that the pump itself is willing to go along with you when you sort out the upstream. You really should be able to force the fuel pump relay on. Just short AF73 to earth when the key is on. If the pump runs, then the relay is fine, and all the power up to both inputs on the relay is fine. If it doesn't run (and given that you checked the relay itself actually works) then one or both of AF70 and AF71 are not bringing power to the game.
    • Kinkstaah
      My BMW E39 528i touring

      By Kinkstaah · Posted

      @PranK can you elaborate further on the Colorlock Dye? The website has a lot of options. I'm sure you've done all the research. I have old genuine leather seats that I have bought various refurbing creams and such, but never a dye. Any info on how long it lasts? Does it wash out? Is it a hassle? What product do I actually need? Am I just buying this kit and following the steps the page advises or something else? https://www.colourlockaustralia.com.au/colourlock-leather-repair-kit-dye.html
×
×
  • Create New...