Cams

[Edd]

I'm currently running HKS 264 11mm lift cams.

Is it really worth me changing these to a higher duration and lift.

My options seem to me tomei 270 12mm or 280 12mm.

the 280's will be best for power but will be a c*nt on the road so if i did change i think i would to the tomei 270 12's BUT is it really worth changing from the HKS ones i have and will it really effect my overall power and driveability?

thanks

 

[Mr GTiR]

YES from what i have heard the Tommie's flow a lot more air than the HKS cams.

i'm looking into the Tommie's ones atm and deffo want the 12mm lift. Not too sure which duration to go for :? . Phone Clive or Andy at RC Developments as they are fitting my cams. Andy has a set on his car and was surprised how smooth they actually are when driving at low rpm and tickover

they are on about putting some 'wild' Tommie's ones in for me lol 8)

 

[robinsongtir]

Edd,
Andy had a set of tomei 270 12.5 fitted to his 2litre and he said to me they are not that bad at low rpm idling but really pull hard past 5000rpm and this was with using a std tubby.On your car edd they will idle slightly better on a 2.2 anyway
Mr Chan you booked yourself in@ RC then?

they reckon 280s might idle a bit lumpy but not as much as people might think.

 

[cmng]

but with tomei 260 or 270 lift 12mm
do there need to change to titanium retainer ?

or just valve spring is good enough ??

Thanks

 

[Edd]

i'm not bothered about a lumpy idle :twisted:

just worried 280's will be bit too much on the road

who's best to speak to at RC and i'll give them a call

 

[Nad]

but with tomei 260 or 270 lift 12mm
do there need to change to titanium retainer ?

or just valve spring is good enough ??

Thanks

We changed the springs to be on the safe side and are running rocker arm retainers. Not cheaper at over £370 for the set.

Nad

 

[robinsongtir]

speak to Clive if you can get hold of him if not ask to speak to Andy he fitted the Tomei 270s to his car

 

[cmng]

if spring and rocker arm stopper can do it it should be ok
since the most costly part is the titanium retainer

 

[pschurr]

Do you guys actually know *why* these longer durations are not impacting idle as much as people seem to think they should... because it seems kind'a moot to be talking about longer cams for more power if you aren't really clued into cam timing? and overlap, and reversion, etc, etc.

When you go longer duration, are you all running adjustable cam wheels and have the cams dialled to any specific angles to impact performance at particular rpm ranges? Or are you mostly running factory cam timing.

I guess the design of the CC is going to influence the nature of crossflow at low rpm, which will in turn influence venting during overlap. In this regard the sr20 valve design is already pretty good, being two on each side - angled toward each other. In the old days, a big banger V8 had (has?) two valves next to each other and crossflow was never any good, so as overlap increased, ventilation went out the door at low rpm, causing reversion, hence missing every 2nd combustion stroke - bingo, lumpy idle.

I think we're not working hard enough to find optimum cam timing, and we just keep pushing the boost up instead. There are NA cars out there making a shyte load more power - due largely to VERY aggressive cam timing.

something to think about (for me anyway)
peter

 

[robinsongtir]

forgot to metion that I would use adjustable cam pulleys to set the timing as well

 

[skiddusmarkus]

Some people say that the factory settings are best but I've bought adjustable pulleys anyway as I don't see how settings for shorter duration,lower lift cams with a different turbo,smaller displacement(up 45cc),different fuel etc can possibly be the optimim for my engine now.
I don't think anyone has actually tested different settings for power before,just what the tuner sets them too.I suppose it's because it's a lot of hassle keep taking the cam cover on and off to get the results.Will be expensive too with RR time.
If one of the cottage industry tuners on here(eg Ginga,Ashills,Antilag) could do it,they could compare results on something like an AP22 which although not as accurate as a rolling road,will give actual real world data such as through gear acceleration and also has a guess at power too.

 

[ashills]

its in the pipe line mate but wont be it doing it till over the winter im affraid

 

[Nad]

Do you guys actually know *why* these longer durations are not impacting idle as much as people seem to think they should... because it seems kind'a moot to be talking about longer cams for more power if you aren't really clued into cam timing? and overlap, and reversion, etc, etc.
peter

Thats because everyone is leaving it on standard timing and going to tuners who dont think its worth adjusting them.

I've read long time ago hence for what I want 260 12's with adjustable pulleys to get plenty of mid range

Nad