9/73-E31-260z Posted August 31, 2013 Share Posted August 31, 2013 (edited) Hi, I just bought my first Z and I had a couple questions about engine performance. Now my car has a stock L26 block with as far as I know stock pistons and crank. But it does have early roundtop SUs and an E31 head. I've done as much research as I could about this head and I know it is known for having good quench, but other than that how will having this head help performance? What kind of compression would I be looking at with an E31 and stock flat top pistons? I know the L26 had a stock C/R of 8.3:1, and it looks like people have calculated this block/head combo to yield about 9.4-9.6:1. Is this accurate? And what would I get if it ends up having dished pistons? I have searched this forum already and all I could find about the E31 on an L26 block was from my own project thread, everything else I found basically Googling the combo but nothing really conclusive came up. I'd really appreciate the help if you guys have any info for me, can't wait to dive into this build. This is the block and this is a closeup of the head, it is an E31 for sure Edited August 31, 2013 by 9/73-E31-260z Quote Link to comment Share on other sites More sharing options...
madkaw Posted September 1, 2013 Share Posted September 1, 2013 It should be a nice bump in performance from a stock L 26 e-88 head. Probably stock flat tops and CR would be a guess. You can google for the Datsun engine calculator and plug in some numbers for parts swapping. This will not tell you if the stock chambers have been altered. I would it would be close to 10:1 , but purely a guess. How's it run?? Quote Link to comment Share on other sites More sharing options...
9/73-E31-260z Posted September 1, 2013 Author Share Posted September 1, 2013 It's not currently running right now, but it was in daily driver condition mechanically before it was parked for a while. Looks like the electrical fuel pump by the gas tank is out but the mechanical one by the block seems to be working. We got it to catch a little bit with me starting it and my friend shooting carb cleaner into the open carbs (real safe huh? ;D ) Should be ready to go sometime in the next week when we get the fuel pump. Quote Link to comment Share on other sites More sharing options...
9/73-E31-260z Posted September 3, 2013 Author Share Posted September 3, 2013 So I was able to find out some more info: early 260's did indeed have flat top pistons. And I found a couple pretty goof engine calculators that seemed to work fairly well. Looks like I should be looking at about 9.66:1 conpression, and ideas on what kind of power this would yield? Quote Link to comment Share on other sites More sharing options...
DatsunZman04 Posted September 3, 2013 Share Posted September 3, 2013 The E31 head had the Highest compression ratio of the Z series heads, they came off the 70-71 z. BUT!!! they also had the smaller valves. Most people install the bigger valves in that head to make them breath in the 70's to have a budget racer motor to run on High Octane fuel. How to modify your Z engine book would tell you everything about interchanging the parts and the cc's of each head. I hope this is somewhat helpful. http://www.amazon.com/Modify-Your-Nissan-Datsun-Engine/dp/1931128049/ref=sr_1_2?ie=UTF8&qid=1378242751&sr=8-2&keywords=datsun+z+how+to+modify Quote Link to comment Share on other sites More sharing options...
9/73-E31-260z Posted September 5, 2013 Author Share Posted September 5, 2013 I will probably have to wait until I can pick up the book, but thanks for the recommendation for sure. I would love to put the bigger valves in but that too will probably have to wait a little bit until I can get the car running haha. Overall would you say this set-up can be a good one? If done properly with good valves, maybe some porting and/or polishing, the right exhaust, and other supporting mods like maybe a carb upgrade? Webers aren't happening any time soon that's for sure... Quote Link to comment Share on other sites More sharing options...
9/73-E31-260z Posted September 5, 2013 Author Share Posted September 5, 2013 I will probably have to wait until I can pick up the book, but thanks for the recommendation for sure. I would love to put the bigger valves in but that too will probably have to wait a little bit until I can get the car running haha. Overall would you say this set-up can be a good one? If done properly with good valves, maybe some porting and/or polishing, the right exhaust, and other supporting mods like maybe a carb upgrade? Webers aren't happening any time soon that's for sure... Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 5, 2013 Share Posted September 5, 2013 "The E31 head had the Highest compression ratio of the Z series heads, they came off the 70-71 z. " Uh, no. E31? Try E30, or O5L... Yep on the "smaller" valves, but again not the "smallest"! Quote Link to comment Share on other sites More sharing options...
DatsunZman04 Posted September 6, 2013 Share Posted September 6, 2013 L20ET = O5L Head L20ET engine in an C210 and R30 Skyline The L20ET is a turbo engine developed by the Nissan Motor Company. It is a 12-valve, 6-cylinder, fuel-injected engine with a single chain driven cam, turbo (non intercooled), and a non crossflow head. It produces 144 hp (107 kW). It was released in the early 1980s[citation needed] and fitted to the Skyline, Laurel, Leopard, Gloria, and Fairlady Z lines of automobiles. The E30 Is also a rare head to find in a Datsun z. I was basically giving him the basics of what came stock here in the US. Quote Link to comment Share on other sites More sharing options...
9/73-E31-260z Posted September 8, 2013 Author Share Posted September 8, 2013 Update: the engine as it turns out is actually an L24... so a little dissapointed there... still, not too bad since it does still have the E31 so I can work with that. Anybody have experience with a P30 block L24 with an E31 head? Quote Link to comment Share on other sites More sharing options...
madkaw Posted September 8, 2013 Share Posted September 8, 2013 You really need to do some researching before you post. Your lucky this thread hasn't been thrown to the tool shed. Come back with some more specific question besides asking if anyone knows about a stock engine potential. No snobs here, just folks that have answered these basic questions a thousand times and it is well documented. Quote Link to comment Share on other sites More sharing options...
NewZed Posted September 8, 2013 Share Posted September 8, 2013 (edited) In summary, you've purchased a Z with an early 240Z engine. Pretty basic. For performance, transplanting an L28 would probably be quickest, cheapest and easiest. You haven't said what year Z you have. I'll guess 260Z since you assumed it was an L26. Apparently the E31 is "uncommon and desirable" to some though. http://www.xenons30.com/Heads.html Edited September 8, 2013 by NewZed Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 9, 2013 Share Posted September 9, 2013 L20ET = O5L Head L20ET engine in an C210 and R30 Skyline The L20ET is a turbo engine developed by the Nissan Motor Company. It is a 12-valve, 6-cylinder, fuel-injected engine with a single chain driven cam, turbo (non intercooled), and a non crossflow head. It produces 144 hp (107 kW). It was released in the early 1980s[citation needed] and fitted to the Skyline, Laurel, Leopard, Gloria, and Fairlady Z lines of automobiles. The E30 Is also a rare head to find in a Datsun z. I was basically giving him the basics of what came stock here in the US. That is incorrect, the E30 is at LEAST as common as the E31, being in all ports of cars while the E31 was a short-time Z Offering. And it was a Z-Head as well. The L20ET was also offered in the S130. It is a Z-Car Head as the article states. This is an international forum, and if you are making absolute statements...be prepared for the possibility someone will call you on bad information when you put it out there... Quote Link to comment Share on other sites More sharing options...
9/73-E31-260z Posted September 10, 2013 Author Share Posted September 10, 2013 I hadn't realized I didn't put it specifically (I'm on a couple other forums as well so I got a little jumbled as to what I had posted where) it is a 74 model year 260z (built 9/73) at least according to the VIN, but the engine had been swapped at some point to an L24. Whether or not the E31 was the original head on this block I am not sure. I have quite a bit of research, and I had never found anything very conclusive as to what the E31 is actually CAPABLE of. As mentioned above^ people just say it's "good" or "desirable" I know that but apart from the good quench what else is so good about it? Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 11, 2013 Share Posted September 11, 2013 Look on the engine I'd plate on the shock tower. What 3 letter/numbers does you VIN Number start with? HLS or RLS? After that, the VIN/Engine ID Plate on the shock tower should match the hard VIN in the firewall, and the engine number should match the engine number on the ID Plate. If the engine number doesn't match no biggie... If the VIN doesn't match you better start looking closer at your car, that's a bad sign! Quote Link to comment Share on other sites More sharing options...
DatsunZman04 Posted September 11, 2013 Share Posted September 11, 2013 That is incorrect, the E30 is at LEAST as common as the E31, being in all ports of cars while the E31 was a short-time Z Offering. And it was a Z-Head as well. The L20ET was also offered in the S130. It is a Z-Car Head as the article states. This is an international forum, and if you are making absolute statements...be prepared for the possibility someone will call you on bad information when you put it out there... I think I need to clear the air out there on my posting and the comments made by Tony D. I messed up when I said the E31 Head had the Highest Compression Ratio of the Z series engines. I never Included the off the wall ( rare) heads like the E30 or the 05L. My bad for assuming he was from the US, where finding a old SKYLINE, LAUREL, Leopard, or a Gloria head would be a task in itself. All heads for these cars are becoming rare due to their age Inclunding the basic ones. As far as my absolute statement? All I did was give more information on the heads thats Tony provided that I left off. I did not give out bad information about the E31 head, I just told him the basics. I believe Tony, is one of the most experanced Z ethusiast out their and I would take his advice anyday, but I think his comments on Bad Information where a little bit unecessary In my opinion. Quote Link to comment Share on other sites More sharing options...
9/73-E31-260z Posted September 12, 2013 Author Share Posted September 12, 2013 Tony - the car is a real 260z, VIN starts with RLS30 and everything. Has two fuel pumps, even says 260z on the dash. I'm kinda over it being a swapped L24 at this point, at least it still has the E31. And I've looked over like 95% of the car that i can get at without having it up on a lift or taking all the interior out. (I have crawled under it and looked as extensively as I could, I even took a few looks while it was on the trailer). Everything seems to be there it's just the engine was swapped. Mechanically everything seems to be there, the AC is gone and there are the odd wiring job issues but nothing too major it seems. Zman04 - I am from the US actually, born and raised sunny San Diego haha. And I get what you were trying to say about the heads. The E31 was the only one offered in the US from those, the E30 head and L20ET were never available on anything here as far as I know. I heard there were only about 10,000 E31s ever manufactured, is that correct? Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 12, 2013 Share Posted September 12, 2013 Yep, if you're RLS then it's an engine swap. As for the E30 being "Rare" AGAIN: it is AT LEAST AS COMMON AS, IF NOT MORE SO than the E31. The only reason to use or get wood over an E31 is because you are in a race class where you are restricted to use them in stock form. Most people use other heads...and in fact the O5L was sold through Nissan Comp in the USA for serious high-level competitors...I know of at least three recently purchased in SoCal from a hoarder who socked them away in the 80's when he was involved in Racing Turbo L28's... Don't believe the internets for your L-Series history...especially for stateside sources. It's woefully misleading. It's like the Internet site that says N42's were an "FI Only Head" when in fact my N42 (as well as several others here) have N42's with ONLY carburettor bolt flanges, and no injection notches. The problem with listening to stateside Z-Car Propaganda is you get a seriously misleading view of the total Z-Car Scene. It's like saying 75 was the first year for EFI...when JECS was putting out units for 240's in Competition in 71! Absolute statements, without reservations or qualifications are usually wrong. By the nature of an absolute statement--it's authoratitve voice...it can only be absolutely right, or absolutely wrong... Qualifications and reservations after the fact invoke "mind in gear before mouth in motion" reminders. Quote Link to comment Share on other sites More sharing options...
Tony D Posted September 12, 2013 Share Posted September 12, 2013 When I can walk through the Pick-A-Part on North Blinn in Wilmington and see a "Y70" head on a late model Maxima...and do a double take to confirm indeed it's an L20E in there...the "rarity" and "exclusivity" of export markets has to be called into question. K Wantanabe & Sons, Mapai International, etc...ALL imported JDM Engines by the CONTAINERLOADS through the 70's, 80's, 90's, and continue to this day. An L20A may be " Rare"...where you exist. But lets not cheapen the word. A US-Specification LHD 1969 Toyota 2000GT is "Rare" there were 9 imported. A Boss 302 Mustang was touted as "Rare" in the Midwest because only 250,000 were produced... A US-Spec 260Z is "Rare"--78,000 produced for 1974 A Fairlady Z then is even "Rarer" as 78,000 were made 69-77... And of those, 417 came with the S20 Engine. Rare is a matter of degrees. Personally, I reserve it's use for items with a production number not in five or six digits... Quote Link to comment Share on other sites More sharing options...
Leon Posted September 13, 2013 Share Posted September 13, 2013 I heard there were only about 10,000 E31s ever manufactured, is that correct? Nope. That number is likely over 30,000 as the E31 stayed atop L24s until mid-71. You have an L24-swapped 260Z, life goes on. One of my 260Zs came with an L24 as well, my guess of why it happens is because it's a cheap swap and people usually don't care about what kind of modifications they do when it comes to the 260Z... Quote Link to comment Share on other sites More sharing options...
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