Cam and head work for 240z with C211 (Y70) head

[Stanley]

Have a fairly low mileage Y70 head/cam assembly on my 240z. It's all stock pretty sure. Stock cam. Don't know much about it but have some info from searches. Came stock on C211's Skylines, Cedric's and who knows what else. Changed the performance quite a bit - torque is strong from 3000 to 4600 rpm. Had it dyno'd, the torque is a straight line rather than a curve but it quits pulling at 5000 rpm. Read somewhere that's what the stock cam does.

No plans to ever race it except once a year at the dragstrip. Got a pretty good ET last time, it's quicker than with the previous stock head, but top speed would be lower I expect. Plans for the bottom end are bore the 240 a little, or possibly go to destroked 280. Can't spend a lot. It's real good on the freeway as is, quick from 65 mph to 90 which is what you need.

Know a mechanic who's recommending a cam. Wondering how the Y70 would do with the stock cam and a little head work. Or what cam and/or head work to keep that flat torque line but get a little more top end.

Also what headers would be good with the Y70? I'm no expert but seems like longer, smaller primaries would be good for midrange torque. The z has an AT.

Any information or links would be much appreciated. It will be a while until I can afford anything so please respond even if it's a year from now.

Edited August 22, 2013 by Stanley

[Stanley]

Anyone? I know the C211's (1980 to early 81?) Skylines aren't that popular or numerous, but I've seen some recently in magazines from car shows in Japan. Saw a thread about one from AUS one recently but nothing about engine. Can't find anything online about building the Y70's, other than Ozconnection's build thread which I studied. The insane midrange torque is great for an AT since it's only got 3 gears. How to keep that and get more top end?

Feel like I might be sorry if I ditch this cam but I don't know.

[madkaw]

Not much info out there on guys that have built this head. It has pretty chambers and smaller ports. You might pose this question over at hybridz. People like TonyD that has experience with the L20 motors should chime in with some specific answers to get you higher rpm power.

I guess my queston would be about how much you can work the ports? Hopefully they were just cast differently with lot's of meat to be carved out. You could have it ported by an experienced builder to flow more for maybe a bigger cam. Looking at the combustion chambers you probably would do nothing, they look great.

I'd say that head heas some very nice potential, and maybe fine just to bigger cam as is. I'd like to find a M47(maxima) head myself, that looks very similiar to your y70.

[Patcon]

As a general rule, my understanding of port size and runner length, longer and/or smaller runners and ports give torque; larger and/or shorter runners give flow. It is kind of hard to get a lot of both. Look at how dual plane v-8 intakes are made versus racing single plane intakes.

Charles

[madkaw]

Just got done reading thru the thread by OZConnection on Hybridz. If you haven't yet, search small port heads over there. Not much specific recommendations for your head, but no bad news either. IMHO, that head would be definetly worth investing time and money. Not sure what your budget is, but I would consider contacting Rebello to get their ideas on how they would approach your search for more HP up top. It sounds like the smaller ports and low end is a great for the daily driver scene that likes that initial pop when pushing the accelerator.

As far as machine work, as said in that thread, it's easier and less expensive to go bigger-ie. valves, ports, combustion chambers. Maybe some bigger valves, port work, unshrouding and a beefy cam you could have something to brag about.

[Stanley]

Thank you, I'll follow those leads as soon as I can. Swamped with work right now, hasn't happened for a couple years so can't complain.