Which head to use in Datsun Engine project

[okayfine]

but im just getting info from others who have done any mods with the L20 mods.

It's way more than that. It's way more than gathering "specs" and throwing the pieces together. By your posts in this thread, you have a long way to go and a lot of research to do before you're ready to buy parts for your engine.

I'd suggest the following books:

How to Modify Your Nissan and Datsun Ohc Engine
Author: by Frank Honsowetz
ISBN: 1555611605

How to Modify Datsun 510, 610, 240Z Engines & Chassis
Author: by Bill Fisher & Bob Waar
Publisher: HP Books 1973
ISBN: 0912656093

You might also find it useful to read through some of the L-series-based project threads, especially something like Byron's "Bronze" build thread. That would give you a better taste about what's involved in a serious L-series build.

and

How to rebuild your Datsun L-series engine
Author: by Tom Monroe
ISBN: 1555611591

[datzenmike]

Here's an example of compressions for the 2.3 as described by Jason Gray using the L20B bored 2mm over and using a flat top piston. (this assumes the custom piston still retains the same pin height as the Z22E and therefore has a -1.45mm deck height.

With open chamber head..... 10.35 to 1
With closed chamber head... 11.05 to 1

Now as you are planning a custom piston, it's reasonable to assume you would increase the pin height by 1.45mm to provide a zero deck height. If so the compression ratios will be:

With open chamber head..... 11.89 to 1
With closed chamber head... 12.84 to 1

I would think you would need aviation fuel for this.

[defdes]

My LZ 2.2 had a custom pop up piston, the open chambered U67 head people are recommending, and was 10.5:1 CR, anything more and you'll need AV Gas.

[Diamond1]

Thanx datzenmike, I believe the 11.05:1 compression is what im trying to aim for. The 10.35 seems cool also, but i just want more power in a lil 4 banger. I've heard that those "How to modify Datsun Engine" booklets were not clear on all modifications by a couple of threads and a couple of people warned that those booklets arent the way to go. Everyone is always referring to Jason Grays page on building datsun engines. sorry if any confusions but like I stated before, i just wanna get a badazz L2.3 engine for everyday driving but has the ballz to get up when i want it too.

[defdes]

11.5 CR and "everyday driver" are mutually exclusive.

[Diamond1]

"mutually exclusive" And your point will be?

[defdes]

Ummmmm..... that 11.5 is not the compression of a daily driver unless you live in an area with "76 stations" (my local race gas provider) which sell 100 octane gas and you have the pockets to supply $75 for a fill up twice a week.

[marx1]

For comparison - I had a L20b with L18 pistons, and A87 closed head, .590 Isky cam and dual DCOE40's. I think the CR was 11.8 (someone could check this) on a project racer. I HAD to run 91 with octane booster upping it to 96.4 octane. It ran OK under low loads, and up to 5k rpm, once I got over that it was ping city. Once I went to 100 unleaded race gas it was fine.

[defdes]

"...100 unleaded race gas it was fine." And your point will be?

[okayfine]

And your point will be?

And your point will be?



Mr. Diamond1, sir, you clearly have no idea what you're talking about, which is fine except you seem to think you know exactly what you're talking about. Why come in here looking for advice and reject all the sound advice given to you? All this will just result in you spending a bunch of money on an engine that won't work when you're done.

For more edification, find and read Xerox's project thread. He's the current owner of an engine built by a PO much like you, with a similar result as you would end up with - it doesn't really work. The PO of Xerox's car didn't have the knowledge to build the engine, merely got "specs" from the internet. And Xerox has had to try to clean up the result.

How is 11:1 compression ratio your goal? Why? Where are you getting the avgas to run that engine? Please don't tell me some version of "My mom's new Honda Civic has a 12:1 engine and it runs fine on 87!"

[datzenmike]

Exactly! Newer engines can run insane compressions because they have precise EFI control of their fuel mixtures, ignition retard and improved piston/combustion chamber design to control pre ignition. The last 4 cyl L head was used in 1980 and IT was a design from over 12 years before that so it's almost 40 years behind the times. You are stuck with and have to work with what you have.

11 to 1 compression is totally do able but will be like a high maintainance girl friend. Fine for a few minutes at the end of the day but an expen$ive, time consuming, attention demanding pain in the ass the rest of the time.(shudder)

[nickledimeme]

God I love these threads......

My dad always say's...."you can lead a horse to water....but you can't make em drink"

[defdes]

God I love these threads......

My dad always say's...."you can lead a horse to water....but you can't make em drink"

Marx1 currently residing in the "Where Is He Now File".

[bertvorgon]

I know with mine, depending on cam setting, I can only tickle the throttle, and other then that it will ping and then go to detonation. That is skirting with 10:1 compression ( before boost). You could NEVER do full throttle runs. 99% of regular, off the shelf octane boosters, will not work either, once the heat starts to go up. I have to run aviation fuel, 100LL, which is very hard to obtain by the average, non-flying Joe. As a daily driver it would break the bank in terms of cost. I paid $1.60 a liter this spring for mine, which is $7.27 for an Imperial gallon. As the boys pointed out, todays cars are so well controlled by that computer, they can get away with compressions you can only dream about relative to our 70's technology.
Shoot for something more modest, and ultimately you will have a car that you can acually tune, and drive to it's potential.