Jump to content
SAU Community

Recommended Posts

so the next upgrade i want to do is a lightweight pulley kit, some of the kits available are underdriven, by like 10 and 30 percent for the water pump and alternator

obviously these underdriven kits are for high reving motors , like drift cars right, slowing down how fast the water pump pumps and the charging rate of the alternator... so would an underdriven kit be a bad thing for a motor that isnt commonly in a higher rev range?? although sumday i am planning to drive it as a weekend track car...

Edited by AYW550
Link to comment
https://www.sau.com.au/forums/topic/283268-underdriven-pulleys/
Share on other sites

for a daily i think itd be best to keep the stock pulley arrangement. nothing worse than having a flat battery every second morning cos the alternator isnt charging as much as it could. plus youd get no real benefit unless you hit the rev limiter every time you do the groceries

as far as i know, your alternator puts out maximum voltage at fairly low rpms. it doesn't charge any more at 2000rpm compared to 6000rmp. same as your water pump. alot of the v8 boys are putting in under driven pulleys with good results.

yeah as was said, unless you are chasing every last possible pony from your motor and have done everything else, don't bother. spend the money on something more worth while that will give you better gains.

hmmm, well i am chasing every possible bit of power i can from my motor, and have now done most of the NA upgrades possible to my r34 without cracking the motor open, the light weight pulley kits advertise 4-7kw more from the motor plus making it more responsive...but a good number of the kits are under driven and was wondering about the side effects

also, does any one know the dimensions of a rb25de crank shaft and crank pulley? im looking for a single belt crank pully set up, im hoping to greatly reduce the rotating mass of the crank pulley as i have removed my AC system and am planning to replace the stock belt driven fan with an electric fan but havent seen any kits with a single belt crank pulley, anyone know of any? could a crank pulley for a different type motor fit on ? id like to avoid the price of the custom route...

just out of curiousity, what mods do you currently have?

well,,,ive done

-wheels and suspension

-romoved entire AC system (to reduce some weight and gain a bit of power)

-battery moved to the boot (improved handling)

-full 2.5 inch exhaust system with high flow cat, high flow exhaust and coby extractors

-POD filter with heat shield and CAI

will do brakes some other day and replace them with slotted ones when the stock discs wear out, but for now they stop me plenty good

that about it really as far as performance mods are concerned....about to put in new coils and plugs, and soon after that swap out stock radiator fan for an electric one as i mentioned above

so, what do you think?

you should dyno your car and get a tune, would be interested to see wha kind of power an na r34 makes

yeah im keen as to get it dyno tested and tuned, after i get my coils in and the probably the pulley kit ill do it for sure, its also a manual but is 4wd, ive tried to remove as much weight from her as possible too...

hmmm, well i am chasing every possible bit of power i can from my motor, and have now done most of the NA upgrades possible to my r34 without cracking the motor open, the light weight pulley kits advertise 4-7kw more from the motor plus making it more responsive...but a good number of the kits are under driven and was wondering about the side effects

:no: 4-7 kw gain, what was that that just flew past my window --why it was a pig--honest :huh: .

;) It'll look good if you get the anodised ones and red will deffinately give the biggest gains, ah-hem :P .

:no: 4-7 kw gain, what was that that just flew past my window --why it was a pig--honest :huh: .

;) It'll look good if you get the anodised ones and red will deffinately give the biggest gains, ah-hem :P .

have you experinced cases where light weight pullies made no difference?? reducing the rotating mass of a motor would decrease its work load, requiring less power to turn its self, they say its a similar effect to that of a light weight flywheel, im not saying i believe their claims hands down, but it makes sense to me...

Edited by AYW550
i would be looking at cams over the pulley set. even without an ecu you are going to see decent gains throughout the rev range. look up prices for a set of poncams

ok ill look into that, i had just assumed cams would be expensive

<br />but they are garanteed to give you decent gains. pulleys, not so much.<br />
<br /><br /><br />

yeah true, ill deffinately look into it, i know sumday ill be opening the motor up and i think cams will be the first thing i do,,,would a power fc computer go well with a cam?

Edited by AYW550
have you experinced cases where light weight pullies made no difference?? reducing the rotating mass of a motor would decrease its work load, requiring less power to turn its self, they say its a similar effect to that of a light weight flywheel, im not saying i believe their claims hands down, but it makes sense to me...

Mate , I'm probably being a bit silly there so sorry but yes to you're question , my last but one 00 WRX, had a reasonable amount of mods so was on and of the dyno a fair bit, it had 178kws at all 4 put on a set of lightwieght pulleys just prior to a ECUtech customtune and it read exactly the same as the previous reading with stock ones.

They have a pretty good effect on VG30DE's, normally good for 10-15hp on one of them. Standard pulley weighs around 7kg!

I always thought that non harmonic balanced pulleys where no good on RB's, they have trouble due to the long cranks, it reaches a natural frequency that fatigues the crank then it snaps. Only what I have heard :thumbsup:

<br />They have a pretty good effect on VG30DE's, normally good for 10-15hp on one of them. Standard pulley weighs around 7kg! <br /><br />I always thought that non harmonic balanced pulleys where no good on RB's, they have trouble due to the long cranks, it reaches a natural frequency that fatigues the crank then it snaps. Only what I have heard <img src="http://www.skylinesaustralia.com/forums/style_emoticons/default/wink.gif" style="vertical-align:middle" emoid=":thumbsup:" border="0" alt="wink.gif" /><br />
<br /><br /><br />

hmmm, well i dont like the sound of that...no pun intended!

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


  • Latest Posts

    • Very decent bit of kit. Definitely black it out I reckon.  
    • Because people who want that are buying euros. The people with the money to buy the aftermarket heads and blocks aren’t interested in efficiency or making -7 power, they’re making well over 1,000hp and pretty much only drive them at full throttle  best way to way make money is know your customer base and what they want and don’t spend money making things they don’t want. 
    • It's not, but it does feel like a bit of a missed opportunity regardless. For example, what if the cylinder head was redesigned to fit a GDI fuel system? It's worth like two full points of compression ratio when looking at modern GDI turbo vs PFI turbo. I'm pretty reliably surprised at how much less turbo it takes to make similar power out of a modern engine vs something like an RB26. Something with roughly the same dimensions as a -7 on an S55 is making absolutely silly power numbers compared to an RB26. I know there's a ton of power loss from things like high tension rings, high viscosity oil, clutch fan, AWD standby loss, etc but it's something like 700 whp in an F80 M3 vs 400 whp in an R33 GTR. The stock TF035HL4W turbos in an F80 M3 are really rather dinky little things and that's enough to get 400 whp at 18 psi. This just seems unwise no? I thought the general approach is if you aren't knock limited the MFB50 should be held constant through the RPM range. So more timing with RPM, but less timing with more cylinder filling. A VE-based table should accordingly inverse the VE curve of the engine.
    • I've seen tunes from big name workshops with cars making in excess of 700kW and one thing that stood out to me, is that noone is bothering with torque management. Everyone is throwing in as much timing as the motor can take for a pull. Sure that yields pretty numbers on a dyno, but it's not keeping these motors together for more than a few squirts down the straight without blowing coolant or head gaskets. If tuners, paid a bit more attention and took timing out in the mid range, managed boost a bit better, you'll probably see less motors grenading. Not to name names, or anything like that, but I've seen a tune, from a pretty wild GT-R from a big name tuner and I was but perplexed on the amount of timing jammed into it. You would have expected a quite a bit less timing at peak torque versus near the limiter, but there was literally 3 degrees of difference. Sure you want to make as much as possible throughout the RPM range, but why? At the expense of blowing motors? Anyhow I think we've gone off topic enough once again lol.
    • Because that’s not what any of them are building these heads or blocks for. It’s to hold over over 1000hp at the wheels without breaking and none of that stuff is required to make power 
×
×
  • Create New...