ryant67 Posted May 28, 2015 Share Posted May 28, 2015 (edited) Pulled this E31 off of my old stroker motor that I spun a bearing on. It's had a little work done, probably the better part of a couple of decades ago. No idea who did said work. It does have the larger L28 valve job done. Question is, what is the ideal for these heads when it comes to unshrouding valves? It looks like a decent bit of work has already been done, but I am questioning the areas highlighted and wondering if some simple touch up work that could better blend things could possibly improve flow further. Edited May 29, 2015 by ryant67 Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 29, 2015 Share Posted May 29, 2015 "Ideal" is a loaded term, but I notched or eyebrowed the block out to the headgasket (doesn't take much) and then put the same cut in the chamber so that there was a smooth transition from one to the other around the open valve. Don't take off enough metal to expose the top or bottom of the fire ring in the gasket. zredbaron's engine uses an E31 and he's documented quite a bit of it. Should be of some use. http://forums.hybridz.org/topic/24798-na-31lhead-camshaft-questions-no-shortcuts-max/ Quote Link to comment Share on other sites More sharing options...
ryant67 Posted May 29, 2015 Author Share Posted May 29, 2015 Agreed Jon, reckon I'll go ahead and change the title from "ideal headwork for E31" to "improving E31 flow". Less hyperbole is always better Yeah, there is still a little room left to open things up further. The heart shape could be smoothed a touch more in the process as well. I've read through Zredbaron's thread a few times now, it's loaded with great info. Only issue is almost all of the picture links are now broken... Were you running an e31, or was it a n42? I have an couple of old n42's laying here as well, so I might use one for practice before touching the e31. Quote Link to comment Share on other sites More sharing options...
madkaw Posted May 29, 2015 Share Posted May 29, 2015 Like Jon said, use the fire ring as a guide and give the valves some more room to breath. Looks like someone has taken a few thou off of there, might get it CC. Clean up the spark plug threads that are showing, make it all smooth with no sharp edges. Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 29, 2015 Share Posted May 29, 2015 Go stick it on a flow bench and quantify flow at given valve lifts at 28" If you are anywhere near 190-200 CFM on the intake, and around 60-75% of that on the exhaust you're likely maxed out and nothing much more will be done. Find out where you are to know where you want to go. Quote Link to comment Share on other sites More sharing options...
clarkspeed Posted May 29, 2015 Share Posted May 29, 2015 That head had a hair cut. Make sure you have correct lash pads installed. And if you notch block, be VERY careful when dropping in pistons so ring doesn't hang up there. Learned that lesson last year. Quote Link to comment Share on other sites More sharing options...
ryant67 Posted May 29, 2015 Author Share Posted May 29, 2015 Go stick it on a flow bench and quantify flow at given valve lifts at 28" If you are anywhere near 190-200 CFM on the intake, and around 60-75% of that on the exhaust you're likely maxed out and nothing much more will be done. Find out where you are to know where you want to go. Roger that, I'll stop trying to put the chicken before the egg. No point in doing any work before I see how it performs as it sits. Quote Link to comment Share on other sites More sharing options...
z-ya Posted June 23, 2015 Share Posted June 23, 2015 (edited) It looks like whoever did the work, did a decent job. You can unshroud more, but keep in mind that the largest bore gasket you can get is round 89mm, so have one on hand before doing anything. You don't want to unshroud into the gasket sealing area. My suggestion would be to unshroud to a Felpro gasket, which I believe is around 87mm. This way you can run inexpensive gaskets. I have two E31 heads, one an original Bob Sharp, another a reproduction I had done. Both require the use of an 89 mm MLS gasket. You can see the build I did here: http://forums.hybridz.org/topic/96584-road-race-enduro-l28-engine-build/page-8 Edited June 23, 2015 by z-ya Quote Link to comment Share on other sites More sharing options...
Xnke Posted June 24, 2015 Share Posted June 24, 2015 Felpro gasket is 88mm. There are tricks to get 250+CFM out of some of the castings, but I do not know if the E31 has enough meat to do it. Personally, I have gotten 221CFM at 0.520" lift with N42 and P90 castings, and there is more left in it. Tony Knight at Knight Racing Engines in Australia does a lot of documentation on his work with the L-series, recently he made 240HP out of an L20B restricted to stock bore and stroke, running a flat-tappet cam still. It involves welding and a lot of hand-reworking, I am looking to apply his recent documentation on an E88 casting soon. Quote Link to comment Share on other sites More sharing options...
ryant67 Posted June 26, 2015 Author Share Posted June 26, 2015 Cheers folks! Z-ya - Thanks for chiming in - your E31 looks similar to what I was thinking I could make mine look like with some extra work, albeit not quite so perfect as yours. Interesting that the pad on the spark plug side of the chamber has been blended in. Great pictures in your thread, and wow, WHAT A BUILD! Right now I am in the process of throwing a N42/F54 engine into my 240Z. This engine is running 9.5:1 compression on a Kameari 1.5mm head gasket. All good and well, but I have no idea what the N42 head work looks like or what it flows. Furthermore, I was told by it's previous owner that it was pinging quite a bit at 10:1 with a 1mm gasket, which was solved with the thicker gasket. As a result of the above, I am thinking I would like to throw my E31 on the same F54, which will run me up to 10.4:1 compression with a 1mm head gasket. If I run a reasonably aggressive street cam like an Isky Stage III (290 duration .490 lift), then between that and the quench of the E31, I should hopefully be good for full timing without detonation on Ultra 94. Seem doable?Just looking to use the best of what I have laying around and maximize what I can get out of the car. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted June 26, 2015 Share Posted June 26, 2015 As a result of the above, I am thinking I would like to throw my E31 on the same F54, which will run me up to 10.4:1 compression with a 1mm head gasket. If I run a reasonably aggressive street cam like an Isky Stage III (290 duration .490 lift), then between that and the quench of the E31, I should hopefully be good for full timing without detonation on Ultra 94. Seem doable? Just looking to use the best of what I have laying around and maximize what I can get out of the car. I know you weren't asking me, but I had a flat top/E31 combo. I shaved the head a bit, used different valves that gave higher compression and did a lot of work cc'ing the chambers and knocking all the rough spots down. It was around 11:1 when done. Ran it with triples and a .490/280 cam. It pinged with anything less than 95 octane. I think Canadian octane is the same as US, RON+MON/2, as opposed to European where they use the higher of those component measures. What I would suggest if you want to run that combo is a bigger cam, but that only works if you have the induction to go with it. So basically, if you have triples or ITBs or some custom high flow FI, then do it. With SU's or stock FI, I'd stick with the 9.5:1 compression. The gains from the compression will be quickly lost if you have to dial back the timing. Rebello sells a cam that is something like .520 lift, BRAAP has mentioned it before, and there are other options for bigger cams too. New engines have better chamber designs, x flow heads, and better cooling, and all of that plus the more complicated FI systems allow them to run a lot more compression a lot more safely than we can. Quote Link to comment Share on other sites More sharing options...
madkaw Posted June 26, 2015 Share Posted June 26, 2015 From what I had studied in the archives here on Hybridz, you don't get enough quench pad with the e31 to fight detonation. I too blended the spark plug area and anything else to avoid sharp edges.Maybe with a controllable FI you could run it fat and get by. My e31 is staying on my L24 not going to try it on the L28. I'm putting my money and time in on MN47 for a hot L28 NA motor. Quote Link to comment Share on other sites More sharing options...
ryant67 Posted June 27, 2015 Author Share Posted June 27, 2015 Jon: Thanks for the info - I've read of your 11:1 experiences in a few threads while searching, must have been such a headache having to mix in race fuel! I do have a cam in my E31 right now that is .520 lift, oddly enough, but I haven't a clue as to the duration, and it has no stampings on it other than the factory "K". Might be worth grabbing a dial indicator and printing off a degree wheel to check the duration, as what I have might be good enough for my purposes. I suspect a small duration number though, given the excellent idle quality I had with it... The E31 was on my 3.0 stroker, which ran some form of flat top pistons, L24 rods, and the V07 crank. Triple 44's for induction. It also ran a pretty thick headgasket though, so perhaps the PO had issues... That engine is toast for now anyway, spun a bearing in a pretty bad way. I never had any ping issues with it though, even running 40 advance all in on Shell 91 octane. Steve: Saw your build thread, the chamber of the MN47 looks just about perfect from the get go, it will be interesting to see how it works out for you. Either way, should be a blast to drive once it's all done! Quote Link to comment Share on other sites More sharing options...
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