RB26 cams in an RB20

[feyd182]

Sorry if this is reviving a dead thread somewhere, but I just started reading up about it and was wondering if anyone here has successfully done this mod. It seems like a cheaper alternative to poncams, the main issue I see others have come up with is getting the car to idle/run properly after the install. Adjustable cam gears and resetting your base timing I know is a must, just want to know if there is more I'm missing.


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[GTSspeed]

Hey,

I have RB26 cams in my RB20 (done from previous owner). The main issue is that the base size of the RB26 cams in slightly larger than the base size of the RB20 cams, I think it's 30mm compared to 29mm. This causes the valves to seat improperly (never close 100%) if you continue to use the hydraulic lifters. Once the lifters fill with oil, the valves don't close. This results in poor compression and poor idle. However, in the high RPM range, you do gain HP due to the increased lift and duration of the cams.

I put some adjustable cam gears in my car and set them at +2 IN and -4EX (it seemed to be what everyone else was doing). Currently, my car runs fine although it has a very lumpy idle (and I increased idle in order to ensure the car doesn't die at the lights, but it's around 1500RPM idle, not 3000RPM like some might suggest.

If you are thinking of doing this, I would highly suggest bleeding the lifters once you install the cams. As well, make sure you get some adjustable cam gears to play with timing.

In the end, if my car didn't already have them, I don't think I would have gone this route. It's been alot of tinkering to make them work as well as I think they should (not alot of experience with other RB20 setups so I can't compare). I would save the money and get poncams or re-grind some RB20 cams since they will be direct drop in and you won't need new cam gears (although they do help if you get some time on a dyno). I know that Skym can add value here......

Hope this helps a bit. I did hours of research on this subject and overall, I don't think it's worth it. If I were to rebuild again, I would likely remove them and put in poncams or re-ground RB20 cams.

[Supraclean]

Good response man, I also looked into this and went with the poncams as your already in there might aswell make it easy. Save up a little money coin and it will be worth it. I love my poncams and I went with new Oem valve seals etc. Get yourself a good tune and your set.

[feyd182]

Thanks for the insight! Poncams are waaaaayyyyy out of my build budget, $1000 for one part of the puzzle seems crazy. I'd be looking at well over $4000 (price of my car) to build the head so it would be worth while to do poncams. Basically I'm looking for a little more punch without having to take out a small loan to accomplish. The main issue I've noticed is that nobody resets the base valve timing once they install the cams, this in my opinion is the root cause of poor idle, etc. Different cams will have different timing compared to stock. Anyone else have any thoughts on this?
Great responses guys! Keep em coming!
Thanks!


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[Supraclean]

Yea well understandable. Either way you look at it building the Rb20 for more then 320hp is going to be expensive for what reliability you will get.

I mean for $4000 you could sell you rb20 swap. Buy a Rb25 and have half of your forged internals and make more hp/tq if thats what your after.

Thats why you dont see allot of forged Rb20s, as much as its cool and different its really expensive. Dont get my wrong im not hating. I love my 20 and am going to run her at 341hp maybe even retune for 360.

Id say get a Standalone ECU,injectors,bigger fuel pump, Electronic Boost controller. And go get a tune from local tuner. Aka Cam at lightspeed is close or Rtcs in Calgary.