cam timing on my hks engine

well this is where shes at both show 4d retarded !

its on a massive inlet and q45 throttle body but starts straight up so im assuming cam timing isnt a tooth out.

im seriously contemplating going to tdi and just putting the verniers to zero as it should help spool then do a run on there rototest, its just a case of being sure it wont get valve/piston contact ?

the car only revs to 7600 rpm anyways as per hks recomendation so id like to gain some quicker spool if possible

im hoping i can gain a 3 - 400 rpm in the spool area and get the power back at the top as the red/black run was with a t51r spl journal, blue is new tune hks t51r spl bb so should match old run with better spool aswell.

WHP

cams are hks 272, what is likely to be the best timing to set them on 0 0 ?

This car had a fortune spent on it, you would have thought at mapping they would have set it at a best of both worlds scenario ref spool/power.

If you put both cams back to zero you will not improve spool, leave the ex retarded and put the inlet to zero or even advance that to improve spool, you will not have an issue with clearance at zero if the cams have been fine at 4 degrees retarded.

Without a timing wheel on the crank, and a dial gauge on the cams the markings are meaningless REFERENCED TO ACTUAL VALVE EVENTS V CRANK POSITION. Belt stretch, block height tolerances / machining, head depth tolerances / machining will all change cam to crank position. Only when you have real time valve event figures referenced to say TDC can you say if the cams are neutral, advanced or retarded, and the graduations mean anything other than degrees cam movement relative to their sprockets. Checking it with the engine in the car is a nightmare, best to do it on an engine stand.

If you put both cams back to zero you will not improve spool, leave the ex retarded and put the inlet to zero or even advance that to improve spool, you will not have an issue with clearance at zero if the cams have been fine at 4 degrees retarded.

thanks for that i couldnt quite get my head around if im safe to retard more or advance from where im at safely.

so advanced inlet cam will gain spool and loose some top end ? i have read in an article that retarded inlet and exhaust cams just give negative results across the board so i am hoping i can find my lost top end power and also gain some spool as ive gone from journal to bb.

This car had a fortune spent on it, you would have thought at mapping they would have set it at a best of both worlds scenario ref spool/power.

as far as i can work out the map was done with a journal bearing turbo hks t51r spl, its now got a ball bearing hks t51r spl bb so turbos are identical just bifferent bearings but the map hasnt been changed, i have gained next to no spool and lost top end power and when tdi checked fueling on the dyno for me compared to there old runs for the car the fueling is richer, so its logical to think as engine has been stripped and rebuilt that cam timing is now different to when it was mapped as it must be getting less air to be richer, yet its running the same boost pressure.

id like the power curve to be abit smoother as it comes in like a sledge hamme,r will be more driveable if the coming on boost area is bigger and earlier.

Without a timing wheel on the crank, and a dial gauge on the cams the markings are meaningless REFERENCED TO ACTUAL VALVE EVENTS V CRANK POSITION. Belt stretch, block height tolerances / machining, head depth tolerances / machining will all change cam to crank position. Only when you have real time valve event figures referenced to say TDC can you say if the cams are neutral, advanced or retarded, and the graduations mean anything other than degrees cam movement relative to their sprockets. Checking it with the engine in the car is a nightmare, best to do it on an engine stand.

i know thats the ideal way but not really an option, as long as im safe i will get them to advance inlet cam as i can only gain from where im at at the moment.

Of course you can always play with it on the dyno and see where the best result is, thats all we did with mine, what lift are your cams, in mm.

Of course you can always play with it on the dyno and see where the best result is, thats all we did with mine, what lift are your cams, in mm.

there hks 272 9.3 mm lift, yours must be a close ish comparison engine wise just i have smaller turbo and cams where did you set your inlet/ext cams ?

just looking for a better start point than both 4d retarded, so on the inlet cam by advancing it to 0 will give more valve to piston clearance than 4d retard ?

I have stock comp pistons and 10.4 lift 280 duration and my pistons get nowhere near my valves, with the 3ltr we had 4 degrees retard exh and 0 degrees inlet to get it to spool at all and make boost with the 2 step, with the 3.4 both cams on 0.

I have stock comp pistons and 10.4 lift 280 duration and my pistons get nowhere near my valves, with the 3ltr we had 4 degrees retard exh and 0 degrees inlet to get it to spool at all and make boost with the 2 step, with the 3.4 both cams on 0.

hopefully my engine isnt interference then its just full hks 3.4 stroker kit and the hks 272 cam with hks verniers, im hoping the verniers are quite accurate as its all hks.

maybe best if i try a 0 0 run then ? or is the exhaust cam retard helping spool ?

someone has just said to me if the head or block have been skimmed alot the equal altered timing might actually be 0 if there making up for skimmed block/head face material.

someone has just said to me if the head or block have been skimmed alot the equal altered timing might actually be 0 if there making up for skimmed block/head face material.

I doubt anyone would use a head or block that needed that amount skimming to build a 3.4, if they had the comp would be higher and your turbo would spool fine, if your not sure then like CW says you will neded to set it up with a degree wheel, what turbo is it??

Who set it up? have you asked why they retarded it or why it looks to be set that way?

Lee dialed mine in on the engine stand with the cam card details, i guess it could still be done with the engine in place?

It easy enough to dial in with the motor in the car, the Titan cams don't even come with dial in info, they just say install em at 0 and play around, the exhaust cam has been retarded to improve spool but the inle who knows, maybe they had a reason.

someone has just said to me if the head or block have been skimmed alot the equal altered timing might actually be 0 if there making up for skimmed block/head face material.

That's what I said in post #4

Sort of amazes me that more people dont experiment with this on the dyno as part of the mapping process !!!! Whats the point of buying expensive pulleys and not using them???

Sort of amazes me that more people dont experiment with this on the dyno as part of the mapping process !!!! Whats the point of buying expensive pulleys and not using them???

they look nice?

BTW the HKS pulleys are not the best, they wear quickly with open timing covers because they are alluminium and only have 3 bolts locating them, there is a chance they can move, my car just ripped the TB tensioner mounting bolt out of a brand new oil pump so thats how much strain is on these things, I would not run the HKS pulleys on my own car hence using Steel JUN pulleys with 5 securing bolts.

they look nice?

More hero parts as I like to call em !!!!! LOL, seriously if a car spools fine but seems a little down on power on what we expect we always try a few diff positions same if it seems to spool slowly, my car with 3L would not make boost on the 2 step, retard timing on ex and weh hey boost !!!!

Who set it up? have you asked why they retarded it or why it looks to be set that way?

 

Lee dialed mine in on the engine stand with the cam card details, i guess it could still be done with the engine in place?

i dont know exactly who built it, just thinking about optimising it how it is if possible.

I doubt anyone would use a head or block that needed that amount skimming to build a 3.4, if they had the comp would be higher and your turbo would spool fine, if your not sure then like CW says you will neded to set it up with a degree wheel, what turbo is it??

the turbo is a genuine hks t51r spl bb gold tag with 1.01 exhaust housing, power plot is 2 bar boost. i dont know where it should make full boost on a 3.4 ? looking at the torque curve it seems to make full boost around 5000 rpm.

I'm fascinated by cam timings, but I find it makes my head hurt trying to work out what happens to the combustion process and what effect that has/should have on the engine behaviour. From what I can work out, retarding the exhaust cam will open the valves later (so you keep a hold of the combustion pressure longer) but close it later, increasing the overlap. While holding onto the Bang part of the 4 stroke cycle must be a good thing, I would have thought an increased overlap is far from what you need at lower revs while trying to spool the turbo up - it'd increase intake charge contamination and lower power? Although counterintuitively this argues for smaller durations, which clearly isn't the case for more power

I'm fascinated by cam timings, but I find it makes my head hurt trying to work out what happens to the combustion process and what effect that has/should have on the engine behaviour. From what I can work out, retarding the exhaust cam will open the valves later (so you keep a hold of the combustion pressure longer) but close it later, increasing the overlap. While holding onto the Bang part of the 4 stroke cycle must be a good thing, I would have thought an increased overlap is far from what you need at lower revs while trying to spool the turbo up - it'd increase intake charge contamination and lower power? Although counterintuitively this argues for smaller durations, which clearly isn't the case for more power

Cough *VVTi* Cough

Yes, are you enjoying your extra 5bhp? IT was put on mainly for emissions purposes, sadly