E30 cylinder head ?

[meakin]

Hello all,

I'm not postive, but I think this is my first post here - but i've been lurking and learning for a while now <img src="http://www.zclub.net/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt=''>

Name here is Lars, and I'm rebuilding a 240z up here in Aalborg,Denmark.

heres my question. I've got this E30 head that came with a parts car, that I dont really know what I should do with. It has smaller valves than my E88, but it also has a considerably smaller quench area(I think you call it).I found a post on zcar.com that mentioned that the CC's on the E30 is  down to 37cc or 39cc (E31 is 42.4cc AFAIK).Would it be worth while to put larger valves in it ? would there be a difference  - or are we talking only a small difference against an L24/E88 engine?

Thanks to any and all help, I'ts nice to know theres a forum a bit closer to home <img src="http://www.zclub.net/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt=''>

cheers,

Meakin

 

[Mr.F]

What you need to do is decide what sort of compression ratio you can run. What quality of pump gas is going to be available and will this support the calculated ratio.

Doing some very rough calculations based on the head cc's quoted and a standard 83mm bore and 240Z stroke, no piston dish:

E88 head 44.7cc : 9.92:1 compression
E31 head 42.4cc : 10.4:1 compression
E30 head 39cc   : 11.2:1 compression
E30 head 37cc    : 11.77:1 compression

Careful measurements will refine these figures, but you can see the effect of reducing the combustion chamber vloume. Any changes will affect these figures eg. removing material from the combustion chamber for flow / improved flame front. Also remember, reboring the block will increase the bore volume and therefore also increase the compression ratio, eg. a 0.5mm overbore with the E88 head gets you up to 10.02:1.

If you need the higher compression, then see if the bigger valves can be fitted into the E30 head

 

[meakin]

Thanks for the reply - you are right offcourse, I have to take things like pump gas in to consideration, aswell as many other things.

There is one thing that puzzles me  - your numbers for compression? I used the L series engine program from this link : http://www.zcarclub.com.au/Lseries.htm With this program I get the following numbers:

E88 Head 44.7cc    : 8.76:1 compression
E31 head 42.4cc    : 9.13:1 compression
E30 head 39cc       : 9.73:1 compression
E30 head 37cc       : 10.13:1 compression

Please don't get me wrong, I'm not in any way questioning you knowledge - I would just like to know if the program is way of the mark, if so I will throw it away.

One on the main reasons this thought process regarding the E30 head, even started was because I thought that the 8.76:1 with E88, that I got from the above program, was a bit low. Therfore I started thinking of alternatives to get the compression up a bit. The bottom end of my L24 engine has just been rebuilt with among other things new 83mm pistons - so I'm not much for the idea of reboring it.
I've also considered going with the L28 bottom end, but I must admit - I love the way the L24 revs so free.

Sorry for the long post, and again thanks for the help

Cheers <img src="http://www.zclub.net/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=''>

 

[Mr.F]

My basic schoolboy maths says:

(cylinder volume + chamber volume) divided by chamber volume = compression ratio

Cylinder volume being pi x r x r x l ie. 3.14 approx x square of the bore radius x stroke (measurements in centimetres).

No account being taken of piston dish (if present), gasket thickness or deck height. Probably the program you are using takes these into account for specific components and gives a more accurate figure. I was only trying to illustrate the trend....for accurate engine building, take the appropriate measurements direct.

 

[Mr.F]

Further to your comments on the use of Lengine.exe - I have renewed my acquaintance with this program and I think there may be a fault in the head gasket component calculation. Look at the figures for the HKS gaskets by comparison to standard and FelPro. The HKS gaskets are supposed to be +1mm and +2mm thicker than standard, but the calculated compressions do not follow. What do you think? I will pursue this to see if there are any other anomalies....

Like I said before - ideally, take the measurements for yourself!

 

[meakin]

Hmmmm now you've got me thinking!

I have no experience with the felpro or the HKS gaskets - I use a standard gasket. I did a bit of snooping around on the internet, and as far as I can find out , It looks like some of the following things "should" be taken into consideration as well.

I'm in way over my head here, so if this info is nothing but rubbish - I will not in any way be offended!

Standard Gaskets: 1.2mm height in compressed form

HKS gaskets : Metal gaskets, as far as I can tell, the 1mm and 2mm definitions are, in fact not 1 and 2mm thicker than the standard gasket, but the exact height measurement of the HKS gaskets. Also - and this confuses me a bit, It seems that they can have a different bore as well. The following insert,is from this page :Compression page
"Moving on, the next step would be the gasket thickness volume. This is the one area many people fail to consider, and consequently, end up with an artificially high CR. You must know the compressed thickness of the head gasket, and the diameter of the gasket opening. For a stock L6 gasket, the compressed thickness is 1.2 mm. The opening, or bore, is 89 mm. For reference, the 1 mm and 2 mm HKS metal gaskets do not compress, so that is the thickness for computations, and they have a 91 mm bore, which will further change the calculation."  However he seems to be calculating for a stock 280zx ,so it could be different in this case.

The same go's for the felpro gaskets , they also seem to have a different bore size against the standard bore.

Don't know if the above clarifies or makes things worse, but please let me know your thoughts on this, as I'm eager to learn.

One day, I will sit down and brush up on my school book maths(2+2 still = 5 right?),make my own exact measurements for the engine and so forth.

The only thing I would still like an opinion on is, with all else being equal,would I be able to feel any difference between my E88/L24 combo and the E30/L24 regarding performance ect ?

Sorry again for this long post - got a bit carried away there (But I am enjoying myself - good post - with good answers)


Cheers

 

[Mr.F]

The HKS gaskets are a confused area as I have seen them advertised as +1mm and +2mm. The Nissan Motorsport catalogue categorically states that the compressed thickness is 1mm and 2mm so I guess we have to go with this. Thus the former will give (all other factors being equal), slightly higher compression than a standard gasket and the latter slightly lower compression. BUT, as you correctly point out, the difference is also in the small extra volume added to the compressed volume as a result of the bigger bore. We can calculate the volume of this very short cylinder and then subtract the volume of the equivalent short standard gasket cylinder if we want to see the difference (or just build this extra parameter into your calculation). I'm not convinced that the HKS gaskets will be of use with an 83mm bore engine....the dead space between head and block created by the bigger bore seems too large. In use, surely this must carbonise up and gradually increase your calculated compression??
I have used the 2mm gasket on a 280ZX turbo engine and so far sealing appears to be excellent despite being composed of three steel gaskets and two shim plates riveted together!

FelPro gaskets are an American make and not readily available in the UK. Could be special ordered. I used to use them for preference as a exceptional quality gasket when building Chevrolet V8s. Nice blue coating seals very effectively.

As to whether you will feel the difference between the two heads - all other things being equal (same valve sizes, same rework of intake and exhaust runners, equivalent mods to combustion chambers, same pistons, gaskets, camshaft etc.), yes, the extra compression will make a difference. However, in practice, the difference might be masked by changes in all those other variables. My feel is to stick to the E88 which is an established base.

 

[meakin]

Thanks,

You make some very good points regarding the larger bore ect.

I've really enjoyed this post and - from the answers, I feel I  have gained a considerable amount of new knowledge. There certainly is a large amount of varible factors that really should be taken into consideration when you do a calculation of this type.

the HKS gaskets seems like a good gasket, but i would imagine the you would have to make sure, that the two surfaces that are to be mated to the gasket are exceptionally smooth and flat, so as to try to prevent the gasket leaking as much as possible. Then again, I guess thats a normal process when rebuilding an engine.

Regarding the carbonising of the larger bore, yes it should change the compression over time, Unless there is "something" in regards to the gasket, that helps prevent this(doubt it though). But even if it did carbonise, would'nt the difference be minute? Also would'nt the compression be high enough to "move", to a certain extent through the carbon? On the other hand I think we are down to details so small now, that there would'nt be that much difference in compression. Just thinking out loud here, as mentioned before, I'm in a bit over my head.

In regards to the E30/E88. I'll take you advice and stick with the E88 for now. However I'm going to keep the E30 just incase I feel like exploring other/different options sometime in the future.

This post got me thinking and has opened my eyes a bit, something I have enjoyed. Also, it may contain some information that others in reading it, may find interesting as well, and that it something that, in my opinion is valuble.

Cheers and thanks again for the help.

 

[Mr.F]

Thanks for the kind words and, yes, you made me stop and think a bit too, particularly with regard to HKS gaskets. I knew I must have altered the entry on my stock list for a good reason......

With engine building (particularly the Chevys I used to work with) every little bit contributes something to the final product. Spending hours on a tiny aspect that doesn't even generate one horsepower may seem like a waste of time, but when the result of all those little details is a winning race engine you can forgive anything. e.g. I don't know many people who are prepared to deburr and paint inside a block. I don't think it gives much horsepower, but you know its there when you are driving "your" engine!

 

[zedhead260]

I thought some one had mentioned E30 heads before.

What car did it come on - and why doesn't it say so in any of my books <img src="http://www.zclub.net/iB_html/non-cgi/emoticons/confused.gif" border="0" valign="absmiddle" alt='???'>?

 

[Mr.F]

No record on part numbers from U.K. or U.S.A. fiches. Possibly a Japanese home market item - maybe from a version of the L20 where the smaller capacity could cope with smaller combustion chambers without whacking up the compression ratio? This would figure with the smaller valves as well.

 

[Albrecht]

Part No: 11041-E3001 ( first type - 1968 ).
Head for 'L20A' engine, as fitted to numerous models of Japanese 'Home' market Nissan cars ( Skyline, Laurel, Cedric, S30 Fairlady Z etc. ).
Was also fitted to some 'Export' HS30 / HLS30 models ( not USA / North American or UK market ) in very small quantities.
Used for quite a few years - so there are more than one type and you would need to know what it came from to get the definitive spec. info.
Not very well documented in the English language.

Albrecht.

 

[Ben]

SNAP!

I've just read this thread & then retrieved the poor, corroding E30 from the collection of stuff that was headed for the dump.

I looked at it when I got a L20A from the wreckers (got knows where they got it from) for the rods & then decided that it wasn't worth keeping, as it had tiny ports & valves. I should have noticed that it had tiny chambers too!

Time will tell if this head survives (some of the valves are corroded open <img src="http://www.zclub.net/iB_html/non-cgi/emoticons/confused.gif" border="0" valign="absmiddle" alt='???'>). But it's in a lubricant bath now & I'll give it some TLC in the near future!

 

[Russ]

Lengine.exe - This program, you say it has some anomalies? Does anyone want to e-mail me a copy and if you like I can write us a new piece of software that we all agree on and is Z club orientated? Might be something nice to have.

Cheers

 

[zedhead260]

So small everything and no use whatsoever unless you're building a hot 2.4 and can't get your hands on an E31.

I'll bin it then.

 

[Ben]

see http://www.zcarclub.com.au/lseries.htm

 

[Mr.F]

The anomalies were, I think, in my head rather than the programme - it works fine, everyone should have a copy! I've re-adjusted my own software at a cellular level.

 

[Russ]

Aww I was looking forward to making us some software, maybe we could do the same, incorporate all the features he is also still to add and do something like gearing etc? Ideas?

 

[zbloke]

Hi
There is a very good site for checking the revs/mph in each gear of your Z or any other car at :-

http://www.geocities.com/z_design_studio/

See ya
Tim

 

[zedhead260]

Wow !! my Zed has a theoretical top speed of 166MPH in 5th @ 6500 rpm.

If only it had the horsepower to push it through that aerodynamic brick wall (130 - ish)