Roller rocker conversion

1. Mikol Established Member Joined: Jun 2008 Somewhere between Bedford and Brixworth Posts: 2373 106 XS 16v Driveway Ornament

   #1 30th July 2012, 18:43

   Evening chaps,
   
   Just crossed my mind today, if it would be possible to convert an engine with solid lifters to a roller rocker set-up.
   
   To be specific, a large-journal Rallye head to the later VTR rockers. Obviously I wouldn't be able to use the VTR cam.
   
   I'm sure the rockers would bolt on but am I missing anything in regards to difference in valve lift (if the roller rockers have a difference cam:valve lift ratio) or even if they are spaced differently in the silvertop heads (I've never cracked one open and had a look).
   
   Thoughts and experience appreciated.
2. blackie_2k5 Saxperience Hardcore! Joined: Oct 2008 Birtley Posts: 22253 VTR Turbo, 106 xsi track slag, Transit recovery, B

   #2 30th July 2012, 18:45

   Don't think it's possible
   
   Why would you want to convert to roller rocker may I ask?
3. Mikol Established Member Joined: Jun 2008 Somewhere between Bedford and Brixworth Posts: 2373 106 XS 16v Driveway Ornament

   #3 30th July 2012, 18:49

   Usual benefits of roller rockers - reducing wear and internal resistance of turning the camshaft
   
   Although a quick search throws up some results of saying the roller rocker assembly is no good past 7000rpm, which is a spanner in the works.
   
   

   Quote:

   Originally Posted by AXracing The problem is that the rockers them self fail. This is why you never see high spec cams for the rollers rockers even with uprated valve springs. I guess the only way to see is try if you fancy risking it. You could always see if you can sell the cam you have and get a new one profiled for solid rockers. Or if you have not used the one you have now they can probably just regrind it for solids.

   It also seems the cam profile is directly affected by the rocker type. That's spanner #2.
4. blackie_2k5 Saxperience Hardcore! Joined: Oct 2008 Birtley Posts: 22253 VTR Turbo, 106 xsi track slag, Transit recovery, B

   #4 30th July 2012, 18:55

   Yeah mate
   
   Most ppl go for the solid lifters, can be revved harder, and have better profiles available for that head
   
   As well and supposedly being a lot lighter fro what I've read.. By this I can only assume it means rotational weight/mass is lighter
   
   There are ppl who know a lot more about the n/a tuning of TU 8vs so I'll let them explain, I never looked massively into when I seen the cost vs gains
5. Mikol Established Member Joined: Jun 2008 Somewhere between Bedford and Brixworth Posts: 2373 106 XS 16v Driveway Ornament

   #5 30th July 2012, 19:13

   And there it is dead in the water
   
   http://www.newman-cams.com/pdf/citroen.pdf
   
   Roller ratio is 1.4 for solid lifters and 1.75 for the rollers, so the solid cam profile will dump the valves almost all the way into the sump
   
   Case closed tbh
6. user_15989 Saxperience Forum Bum Joined: May 2007 Posts: 4857

   #6 30th July 2012, 20:45

   As blackie_2k5 corectly said, the norm is for people to upgrade roller rocker engine to solid lifters if there tuning the engine. The roller rockers are rather naff and tend to fall apart. This is why you tend to only see very mild performance cams available for them. You would be taking quite a big step backwards fitting them to a Rallye head.
7. tweeqd Established Member Joined: Mar 2006 Farnham Surrey Posts: 1542 AX GT 16v turbo 6 speed with NOS 205 gti6 E 320

   #7 30th July 2012, 21:59

   i know lot of people say the roller rockers are shit but mine did over 10k miles with a rev limit of 7250 and 190bhp and have now done 4k with 262 bhp and a limit of 7600
   i do have a custom made cat cam and piper valve springs
8. dannygti Saxperience Post Whore Joined: Feb 2006 dudley United Kingdom (England) Posts: 6790 106 gti/ SEAT LCR

   #8 30th July 2012, 22:08

   Some of the best Honda engines use roller rockers in fact the civic type r engine with just uprated valve springs,retainer,keepers can rev to 9.5k all day long.
   
   Sorry for my semi pointless post
9. blackie_2k5 Saxperience Hardcore! Joined: Oct 2008 Birtley Posts: 22253 VTR Turbo, 106 xsi track slag, Transit recovery, B

   #9 30th July 2012, 22:11

   My r dropped a valve with standard valve train on standard rev limit
   
   Didn't like being revved haha
   
   Broke the rocker arms the lot
10. user_15989 Saxperience Forum Bum Joined: May 2007 Posts: 4857

    #10 30th July 2012, 22:28

    Quote:

    Originally Posted by dannygti Some of the best Honda engines use roller rockers in fact the civic type r engine with just uprated valve springs,retainer,keepers can rev to 9.5k all day long. Sorry for my semi pointless post

    However again it is becoming more common practice to convert these engines to solid. But then engines such as the old A series its often to go the other way. It really depends on the application to what works best.
11. Mikol Established Member Joined: Jun 2008 Somewhere between Bedford and Brixworth Posts: 2373 106 XS 16v Driveway Ornament

    #11 30th July 2012, 22:49

    In general rollers do seem to be the much better option in terms of mechanical sympathy and engine longevity but like you say, if the Saxo ones aren't capable of anything more than they were designed for, then that's that. I suppose you can't expect a budget manufacturer to do anything less.
    
    I'm sure there are some very good, much stronger ones out there, just not for a Saxo.
    
    Thanks for the input