What head would be the best.....

[Dan Baldwin]

Whoops, missed the L26 bottom end. L26 has ~8.3:1 CR, IIRC, with a 47.8cc head. With the 53.6cc P79 head, CR is ~7.7:1! N42 (square exhaust ports like you have now) will bump it to ~8.8:1.

 

Or you could shave the P79 and shim the cam towers.

 

Either way, on that bottom end, you'll be fine on 87-octane pump, so a bit of silver lining...

[phantaz]

ok..bit confused..P79 has round or square ports... im pretty sure they are round?? but ive been fooled before =)

[BRAAP]

N-47, MN-47 and P-79 have round exhaust ports. E-31, E-88, N-42, and P-90 have square exhaust ports.

HTH

[hoov100]

so wich is the best head for a stock engine w/ flat tops and still can be used with regular unleaded?

[phantaz]

got me lol im absolutely lost but im learning..

Paul thnx so much for all your input and to everyone else for helping out.

 

looks like he wants to do some headwork now after i let him read this..and im sure hes going to have a few questions along the way so sorry Paul...im sure ill be annoying you in the future lol

back to the question at hand now lol i went to check his block number and the damn heat plate he built to blcok exhaust heat to keep the gas from boiling out is covering wehre you can just see the motor mounts let alone the side of the block.. and from what i read here. the l26 motor is a lower compression motor so runs ok with hi grade premium... would it be feasible to just have the head shaved to bring up the comp a little or does he need to go ahead and find a 280 block to get the higher compression that he had in his other z before ??? he really misses the snappiness that other z had. i have no idea if just doing a piston change wou be just as expesive as finding a higher compession 280z block. thoughts?

[BRAAP]

We have saying in the engine building business. “Always build as much displacement as you can afford”. Going from 2.6 liters to 2.8 liters will deliver more gains in of itself than even the most ideal head swap, (unless the head has been extensively massaged of course). If he can find a complete ‘81+ ZX L-28, (flat top pistons with the P-79 or P-90 head), he’d be way better off from the get go, then it is just a matter of getting the carbs dialed in “properly”.

I can’t emphasize how important proper tuning is. We could spend 10 hours hashing out which untouched stock cylinder head would be ideal for your fathers L-26, and this theoretical “ideal” cylinder head may perform just a tad better. That tad better performance being a few maybe 10 Horse power tops, due to the head swap alone, is something that most of us wont feel in the seat of the pants.

Here is one little story of just how important proper tuning of the “complete” engine package, mainly fuel and ignition, really is.

Years ago I ran across a gentleman who thought his triple Webber L-28 powered 240Z was the fastest Z in the USA. How do I know this you ask? Well, he told me so himself so it must true, right? Any how, he rattled off big camshaft specs, massive port work, huge exhaust, radical hot ignition parts, and the list went on and on. Listening to this gentleman spew just how special his L-28 powered 240 Z was with the list of go fast goodies and mods performed to it, there is no doubt in anyone’s mind that the car should be fast be any standard. Well he want ed to prove it by running me and my lowly mostly stock 280 Z. I turned him down time and again knowing my car was no match for this monster Z. I finally reluctantly accepted his challenge and all along I knew for sure his car would out run my lowly little 280 Z even if he short shifted. My car was a ’75 280 Z street car and the engine consisted of a completely bone stock ‘78 L-28 short block with the OE dished pistons, N-47 head that I personally did some valve unshrouding on, nothing else. OE stock ’78 cam, original Nissan Hitachi EFI, header, lightened flywheel, recurved ign advance, and countless hours of dialing in the ignition curve and tinkering with the EFI. Pretty much I was running a nothing special L-28. We ran heads up and I whooped him at approx ¼ mile by several car lengths. He was pretty hot under the collar to say the least and couldn’t believe his super hot rod L-28 powered 240 Z just got whooped by an obese mostly stock 280 Z with the lowly Nissan EFI and stock ’78 smog camshaft. So we ran again, same outcome. Never saw that gentleman again. FWIW, my car at the drag strip ran a measly 14.4 @ 97 MPH, not a remarkably fast Z, but also not to shabby for stocker. If his car had all the goods he claimed it had, it was easily capable of 12 second time slips in the ¼ mile, but apparently, his poor super hot L-28 powered 240Z was in a very sad state of tune. Moral to the story, you could have the best most optimum combo in the world, but if it isn’t “TUNED” properly, all the best parts in the world wont do you squat. That same car received a very mild Small block Chevy 350 a few years after that. The V-8 engine had a mild cam and idled at a glass smooth 750 RPM, no lope whatsoever. Induction consisted of just a basic Edelbrock performer intake and Holley carb, heads were stock Iron heads with 1.94”/1.50” valves, though with a little porting work from yours truly, again nothing special, just a mild average garden variety Chevy 350, but with lots of time invested in tuning the ignition and fuel. With that engine, my 2700 lb 280 Z ran 12.3 @ 113 MPH at the imports drag races with completely wrong gearing and some really cheesy 195 60 HR 14” all season tires.

Based on what I’ve gleaned from your posts, your father wants snappy quick performance and you guys are hoping that a cylinder head swap will achieve jsut that. I think his time and money at this point would be best spent on tuning what he currently has and/or possibly swapping in a late model L-28 with flat tops and either the P-79 or P-90 head and of course dialing that package in.

All else begin equal, you could run a dished piston E-88 combo, or a flat top P-79 combo and sure there should be a few horse power difference between the two different engine combo’s on the dyno, (the power nod going to the flat top P-79 combo), but I truly feel the small difference in hp would not be felt seat of the pants. Again, I truly believe at this point that if he just had his current set up truly “dialed in” properly, it should perform very respectably and most likely put that grin of yesteryear back on his face, that is if the valves and rings in the current power plant are sealing properly. Just swapping on a head that might be a little more ideal than his current head, even if this new head is the most ideal head for his pistons, the head swap itself won’t deliver all the goods. The “goods”, is in the state tune…

 

I have a feeling that what I just wrote, isn’t what you really wanted to hear and if so I apologize, but I truly and honestly feel that tuning is where most performance lies. He already has good foundation of go fast parts. If it were my car, I would definitely try to dial in what is already there, or swap in a late model L-28 long block under the current induction system and dial in that set up.

[phantaz]

hear hear... this is why i come to this forum =) lots of good advice that taken objectively.. will get you farther then one direct answer at a time =)

 

now that being said... answer my damn question LOLOL just kidding

 

looks like were headed to Tulsa Tueasday to buy a 82 block with no head.. since he has the P-79 already this should hopefully help out wth the snap he has been looking for... he called the guy he sold his other block to and it was a 81 flat top ..which is why the guy wanted it. whenhe bought this late modl 260 it had a cracked head so he stuck his head and carbs on this 260 after gutting all the efi which from what ive read here is pretty much why its lost a little "snap"

 

Triple webbers are by far some of the most awesome looking items in an engine bay.. and take about as long as you own the damn car to dial them in =) ive wanted to go to trips for awhile but my Dad refuses to help me since there is nothign wrong with my EFI i have now... he just grins and says " im to close to the grave to be fooling with a new set of trips LOL.. cracks me up.

 

hes been workign on his for almost 12 years and says while they work fine they are not perfect so i think ill just cave in and go MS instead. =)

 

back to the subject... hopefully this will help him and while we have the head off...can you recommend any easly found books to do a lttle porting and polishng that might help??? since ive done a few items such as intakes and such ive learned the hard way to "take a little, check it ,and double check" instead of just grinding away =) im definatly keeping the grinder away from the old man... he gets a little impatient lol

 

thnx for the info as usual and anyone else pls share your thoughts.

[BRAAP]

The ’82 short block, if it has the OE pistons, will be flat tops and with the P-79 head will make for a great combination.

As for porting. The How to modify your Nissan engine book written by Frank Honsowetz is a great book. He doesn’t come right out and give away any porting secrets, but if you read and reread the heads section, some things will pop out from between the lines and will point to the L-series weak sports, (hint hint… valve shrouding). Also, if you peruse the threads I linked earlier in this thread and study the pictures “carefully”, that should be enough to get you DIY head porters going.

We are actually building a P-79 right now for Hybrid member that is getting the full port treatment, Rebello cam and possibly N2O. If he is reading this thread, he may be nice enough to allow pics of his head and the port work we have done thus far to be posted, though that is his call.

[Silent]

The ’82 short block' date=' if it has the OE pistons, will be flat tops and with the P-79 head will make for a great combination.

As for porting. The How to modify your Nissan engine book written by Frank Honsowetz is a great book. He doesn’t come right out and give away any porting secrets, but if you read and reread the heads section, some things will pop out from between the lines and will point to the L-series weak sports, (hint hint… valve shrouding). Also, if you peruse the threads I linked earlier in this thread and study the pictures “carefullyâ€, that should be enough to get you DIY head porters going.

We are actually building a P-79 right now for Hybrid member that is getting the full port treatment, Rebello cam and possibly N2O. If he is reading this thread, he may be nice enough to allow pics of his head and the port work we have done thus far to be posted, though that is his call.[/quote']

 

 

the "how to book" is effin great!

 

and yes i read all the posts, cause i get bored easy.

 

 

also, phant, if you want a head, im sure i can come up with it in about 2 days time.

e31 on up to p90a, and mn47 if so desired.

[phantaz]

thnx Braap...im lookng for that book as soon as i log off here =) and i have a few of your posts book marked so i can look at pics.. if you know of any that really show the shrouding thing let me know.. .. and we just picked up the block this morning..supposedly only had 85k miles on it but looks like Pops decided to actually go through this one.. honed, new rings, cleaned and pretty then as i said maybe a little head work ... new summer project has offically started ..here we go =)

 

thnx silent but since he already has the p-79 and he didnt really drive it much to begin with.. having it down while we go through this isnt a biggie.. =)

[Silent]

braap, you can post pics of it, it doesn't bother me any really. maybe one or two people locally view this board anyways, so the cat isn't out of the bag as of yet {im a sneaky lil guy}

 

phant, thats cool. i'll have an n47 forsale here shortly with 15k on it, minus the cam, and rockers {they are both screwed}. just a tip for ya, with 142 rwhp hp, my 280 went 14.5's all day long. that might help in some way of trying to figure out how much hp you want and how fast you want to go. then again torque was around 175-180 ft lbs, depending on how i tuned it

[Mack]

for an L26, i wouuld say the best head to swap on would be an MN47, for the simple fact that it has a large exhaust and a small intake, which is what you will want with the L26's smaller bore.

 

If you un-shrouded the valves a bit, you could get the compression down to what SOME people deem "livable" especially in an L26. I cant remember, does an L26 have dished pistons or flat tops.... its been a while since Ive seen an L26.

[Silent]

for an L26' date=' i wouuld say the best head to swap on would be an MN47, for the simple fact that it has a large exhaust and a small intake, which is what you will want with the L26's smaller bore.

 

If you un-shrouded the valves a bit, you could get the compression down to what SOME people deem "livable" especially in an L26. I cant remember, does an L26 have dished pistons or flat tops.... its been a while since Ive seen an L26.[/quote']

 

should be dished

[phantaz]

i believe its dished... but we have an 82 flat top now so this should be a good combo with the p-79...

 

Braap but now after reading your post im a bit worried..

he has a schneider racing cam in it LOL ... but hes had it for 8 years so i think its safe for now, like i said he doesnt race this car but might take it to a road race track maybe 2 times a year. =)

and thats where he got the valve springs and stuff also and they have held up well.

 

thanks for the offer Silent and i would love to see some of the head work photos... especially any of the shrouding shots =).

 

one thing at a time =)

[Silent]

thanks for the offer Silent and i would love to see some of the head work photos... especially any of the shrouding shots =).

 

one thing at a time =)

 

thats purely up to him {braap} on posting the pics. im all for it, because i personally haven't seen any yet either

[phantaz]

as busy as he his with the other projects going on im not in any hurry but i would love to see some so i can get an idea of what im looking at =)

 

Silent, aree you up in Oregon also??

[Silent]

as busy as he his with the other projects going on im not in any hurry but i would love to see some so i can get an idea of what im looking at =)

 

Silent' date=' aree you up in Oregon also??[/quote']

 

nope, im here in kansas city actually. bought my turd box in stillwater oklahoma. if you want help, say, if you go carbed, lemmie know. i could use a road trip

[BRAAP]

.......Braap but now after reading your post im a bit worried... he has a schneider racing cam in it LOL ... but hes had it for 8 years so i think its safe for now, like i said he doesnt race this car but might take it to a road race track maybe 2 times a year. =) and thats where he got the valve springs and stuff also and they have held up well.

 

Silent has first hand experience with the Schneider cams, (he is currently tearing down his current engine to clean out all the metal flakes that used to be cam lobes), and as such, his new cam is a fairly radical cam that we had Rebello grind for his P-79. I’m sure Silent would be glad to tell all about his Schneider cam woes…

[Silent]

Silent has first hand experience with the Schneider cams, (he is currently tearing down his current engine to clean out all the metal flakes that used to be cam lobes), and as such, his new cam is a fairly radical cam that we had Rebello grind for his P-79. I’m sure Silent would be glad to tell all about his Schneider cam woes…

 

 

missing 4 cam lobes

everytime i dynoed it was lessand less.

final dyno time, on a mustang dyno was 141 rwhp, and 160 ft lbs

on that number, maybe less the car went 14.5 @ 97 mph

 

either im a hell of a driver, or someone was pushing me.

 

anyways. yea. i advise to stear clear of msa cams, as for they are schinder cams. i have seen many of them barf, 2 cars locally, not including mine. purely up to you really.

 

on a side note, my engine bay is secksay now!

[Dan Baldwin]

I had a Schneider cam give up a lobe on me after ~16 months or so. They still replaced it under warranty. When I got the new cam, I checked to see that all the oil dribble holes in the lobes were drilled through. Sure enough, one of the holes only barely made it through to the rifle drilled passage in the middle of the shaft, just a pinpoint. So I drilled it through. I told them about it but I have to wonder if they're still not drilling all the dribble-holes all the way through...