L26 head

[jbuttenshaw]

just out of interest which head flows better out of the l24 head or the l26 head?

[Gav240z]

Tricky question

L24 had 2 heads on a 240z anyway a E31 E88

L26 to my knowledge only had the later E88

The early Z's had the L24 E31 combo high compression.

The 72 Z had the first gen E88 same as E31 High Compression Bigger exhaust valve.

The L26 E88 combo was a lower compression version of the 72 Z head.

So really it didn't flow any better than a later Z head and the loss in compression probably meant it wasn't as good but in terms of flow yes better make sense?

If you wanna confuse the situation further take into account other cars with L24 and L26 engines... eg: skyline.

The main point is any L series head can flow well with the right work done the P90 being the best to begin with and the N42 close second.

The P79 had round ports less desirable.

http://www.geocities.com/zgarage2001/

under cylinder heads.

BTW have you tried the search function on the site?

This is a topic that comes up alot,

Gav:classic:

[jbuttenshaw]

thanx alot for that thats very helpful. that site is pretty good too. sorru a bout not searching, new to the forums. Thanx

[Carl Beck]

Gav240Z wrote:

>Tricky question

>L24 had 2 heads on a 240z anyway a E31 E88

>L26 to my knowledge only had the later E88

>The early Z's had the L24 E31 combo high compression.

Hi Gav (everyone)

The L24 E31 combo was used on the 1970 Series I and 1971 Series II 240-Z's. Brian's site says only on the 70's... and that is incorrect.

>The 72 Z had the first gen E88 same as E31 High Compression

>Bigger exhaust valve.

No - The 72 E88 was a bit lower compression and had the same valve size as the E31. The 72 E88 had better flow.. so HP ratings stayed the same even with lower compression between 71 and 72 Model Years.

>The L26 E88 combo was a lower compression version of the 72 Z head.

It was lower compression, had a larger exhaust valve and completely different shape to the combustion chamber... it was a smog head..

>So really it didn't flow any better than a later Z head and the loss in

>compression probably meant it wasn't as good but in terms of flow

>yes better make sense?

The E88 on the 260Z isn't a good performance head because of the combustion chamber design. Even though it had a larger exhaust valve.. I wouldn't assume it flowed any better than the 72 E88.

>If you wanna confuse the situation further take into account other cars with

>L24 and L26 engines... eg: skyline.

>

>The main point is any L series head can flow well with the right work done

>the P90 being the best to begin with and the N42 close second.

Generally true - if you spend enough money any head can be made to flow better than it did. However among L series heads, some simply have better design intake and exhaust port runners cast into the head to begin with. The racing shops that have flow benches seem to prefer the 72 E88, the N42 and the P90.. as starting points.

>The P79 had round ports less desirable.

>

>http://www.geocities.com/zgarage2001/

>under cylinder heads.

Way to many incorrect statements there related to heads.

See: http://ZHome.com

Look in the Section titled Z Car Technical Library, then under "Heads".

FWIW,

Carl

Carl Beck

Clearwater,FL USA

http://ZHome.com

[Gav240z]

As you can tell I'm still learning I have found the How to modify your Nissan & Datsun OHC Engine to be a good book so far would you say that is more error free than the Z garage site?

The Z garage site is quite good despite it's errors as you point out.:classic:

[Carl Beck]

Gav wrote:

>As you can tell I'm still learning I have found the How to modify

>your Nissan & Datsun OHC Engine to be a good book so far would

>you say that is more error free than the Z garage site?

>

>The Z garage site is quite good despite it's errors as you point out.

Hi Gav: (everyone)

I didn't mean to devalue the entire "Z Garage" site - just felt obligated to point out that the information published there, on heads, is in many ways technically incorrect.

Brian's site has a lot of individual work put into it and it provides a lot of useful/helpful data and information for many people. We back up his site just so the data/info won't be lost. We have always commended Brian for his individual efforts and he has contributed any information we requested, to be republished on the Z Car Home. None-the-less you have to take everything with a grain of salt, it's not gospel, just his personal experiences.

The "How To Modify Your NISSAN/DATSUN OHC Engine", Nissan Part Number 99996-M8012 was published in 1986. So it's now 18 year old information. Much of the information in that book is republished, and some of it is updated from, the "how to modify DATSUN 510 610 240Z engines and chassis" DATSUN Part Number 99996-M8010 first published in 1973. Now 31 years old.

Both books provide a lot of good basic information and many of the basics don't change much over time. However by todays standards, with 20 plus years of advancements and racing history behind us - I wouldn't put too much weight on the information in either historic source.

In terms of "real" or "constant" dollars - there has been huge advancements in the past 20 years as to how the average person can gain more torque and horsepower for their L series Z's. The actual costs of Turbo Charging, or of installing a belt driven Supercharger have come down to a fraction of the costs 20 years ago. The availability of very affordable aftermarket Digital Engine Management Systems opens up entire performance pathways not really covered in either of those old books.

There is a huge difference between the pathways taken to building a "street" performance L series engine today - and the one taken to building an L series engines to comply with some set of regulations, established by some competition sanctioning body, for some specific class of racing.

Both the "how to modify" book have lots of good basic engine prep info and they certainly are good to have as basic info... but a lot has changed in the performance market over the last 20 to 30 years. Right now, there is no verified, 100% accurate source of information about how to modify the L series engines using todays technology. Mostly a huge volume of information on the Web - about what others have done. We all simply have to wade through it and take our best guess as to what to follow..

Of course public discussion helps shake things out too.

FWIW,

Carl

Carl Beck

Clearwater, FL USA

http://ZHome.com