Choices

[madkaw]

I would think the later e88 would be similar to the n42 which was put on the dish piston engines. It might be the least amount of work to get you going since it has the larger exhaust. Maybe just freshen it up and go. You could sell off either 31 or 97 to pay for some it.

[EuroDat]

Steve, Im far from a specialist on these heads, but wasn't there 3, some say 4, different E88 heads? They often quote the earlier head as having similar chambers to the N42 and the later having emmision chambers. You are running an E88 in your set up. Maybe you can shed some light on the subject?

Like always with the internet, if you search long enough, you end up knowing less than when you started.

I have read about two variants on the L24 and some even refer to a third very early E88 that more or less has the same chambers as the E31. The L26 had the later emmision type with the bigger exhaust valve. If you consider them as 4 versions, the first two have the desired chambers with good quench and the last two have the high emmission chambers and poor quench.

That is why people often recommend the N42 becuase it has a similar chamber design and quench to the early E88 and already has the larger L28 valves.

This might influence the decision on which head to use.

As a general rule, they seem to line up as follows:

I The E31 and the very early E88 came with the 4 screw SU carbs. To +/- aug 71

II The "normal" E88 came with 3 screw carbs and the carbs had water heating. To +/- aug 72

III The "emmision" E88 came with the flat top carbs on the L24.

IV The last "emmision" E88 came on the L26.

Having an L28 with dished pistons, I would be inclined to at least consider the option of searching for a N42 head and maybe trade or sell the others. If the E31 wasn't malested and still original it would be worth a lot to the L24 guys.

That would give you around 8.4:1 CR.

[Randalla]

Thanks EuroDat. Good info and solid advice. Since the E88 I have came with a bunch of parts I purchased I don't have any idea what year car it came from. Is there a way to visually tell what I have? Would be helpful to know whether I keep it or sell it. 

[siteunseen]

There's a hump next to the plug threads, I believe. Do a google image search and you'll see it

I can post a picture later. I'm away from my February '72 E88 now. Sorry.

[cgsheen1]

Randalla, the E88 in the back of the shop is a '73 and had flat tops when it came in here.  I have a L26 with an E88 at home I can take pictures of if it'll help narrow down which E88 head you have.

[madkaw]

Try this

 

http://forums.hybridz.org/topic/62691-l6-heads-pics-and-descriptions/

[Zed Head]

You can spend a lot of money on an E31 or E88 head to make it about like an N42 or N47 head.  The N42 and N47 already have the biggest valves, not bigger but biggest.  And, from what I've read, and from what little I know about it, none of the head options have very good chamber designs.  And with dished pistons, there is no quench action to consider.  If you have the parts and the math works out, the E31 and/or E88 can make sense, but if if you can find one, a stock N42 or N47 will give you everything that a valve replacement on the other heads would give you.  It's already done.

 

Seriously, Nissan has already done the work to make a head that works well on an L28 with dished pistons.  Anything less than 44 and 35 is choking the engine compared to what the engineers calculated. 

 

Just adding for emphasis.  A lot of the older racer knowledge was developed to stay within race rules, I believe.  You don't need to do that.  I would put a list of costs together and just pick the cheapest number that's still within your budget.

[madkaw]

Zed is very correct in a very common sense way. I know you have all these heads laying around but the head developed for that dish pistoned engine would be best and probably the least investment-especially if you want to sell off any of the ones you have. It's a non quench head so a matching head would probably work best. A late e88 would best as far as valve size but it isn't until the n47 that has steel seats?

Tuning will always be the biggest issue as far as power.