P65 EFI intake manifold

[stagefumer11]

Hey NZeder, I have that same Intake on my '79 Fairlady Z, and it has the dual throttle butterfly - one smaller and one bigger. I'll also share some pictures for those interested. The diameter of the head-side runners are 27mm compared to 30mm on a normal manifold.

P65 Intake_1.JPG

P65 Intake_2.JPG

P65 Intake_3.JPG

P65 Intake_4.JPG

P65_Intake_4.JPG

 

Nice to see other New Zealander's on the forums

 

plenty of us here mate

[Daeron]

You mentioned throttle body, mine has the twin throttle plate setup and both are about the same size.

 

Sorry if I am nagging, but I would presume that you have, then (in the context of this thread) "the throttle body on the left?" What size are the butterfly bores? "About the size of a dime.. [or a] ..nickel" is vague to say the least, and it would be nice to get better data.

[kolonelklink87]

Sorry if I am nagging, but I would presume that you have, then (in the context of this thread) "the throttle body on the left?" What size are the butterfly bores? "About the size of a dime.. [or a] ..nickel" is vague to say the least, and it would be nice to get better data.

 

from memory the larger twin throttle is ~40mm x2 (it could be 38, i remember it was hard to measure down there)...

I'm not sure about the one with two different sizes... if you turn out wanting the larger one i still have it sitting in a box on my garage bench

 

-pete

 

p.s. ... I wonder how many mm a nickel/dime is? not a standard imperial-metric conversion

 

p.p.s. ... looks like i'll have to measure it when i get home; lots of conflicting info on here

[evil_datto]

Mine off a L20 was a 'P65' & 28mm runners, which were suited to the Y70 head (30mm ports) whereas a normal L28 intake is about 30mm with 32mm ports on the head.

 

You could port the runners to match a L28 head & be equal to a normal L28 intake

I think mine was a single throttle. You may want to swap the TB out for a single plate. I have a twin butterfly on my L28 and had measured all my throttle bodies & my measurements of the twin butterfly weren't very impressive. IIRC the first butterfly is slightly smaller by about 1-2mm diameter. I'll get the total area measurement comparasins in a little bit.

[evil_datto]

I was wrong. So I have three or four different throttle bodies.. Here's the two twin TB's details.

 

L20A Twin Butterfly: First butterfly = 25mm, Second = 40-41mm

First butterfly opens to about 80% @ 1/2 throttle, then second butterfly opens from closed to fully open during 2nd half of throttle.

My guess (probably wrong) is that the huge increase in flow area after half throttle is to make up for the long runner manifold - low end torque rather than top like the L28 manifold.

First butterfly area = 490.9mm2

Second butterfly area = 1256.6mm2

Total area = 1747mm2

 

L28 NAPS Z Twin Butterfly: (From memory, It's in the car atm.) First butterfly = 32mm, Second = 35mm

First butterfly area = 804.2mm2

Second butterfly area = 962.1 mm2

Total area = 1766.3mm2

 

And the P65 intake runners diamater is 27mm (572.5mm2) each. The Y70 head is either 29-30mm2. I'll take a look later.

 

If the normal L28 TB butterfly's are 50mm, then it's 1963.5mm2.

Edited October 12, 2009 by evil_datto
adding info

[Tony D]

The smallest butterfly maximizes intake manifold vacuum for 85%+ of the driving most people will do. It can 'tame' a low gear ratio by giving very sluggish tip-in response.

Chevrolet Suburbans have a non linear throttle that does the same thing.

 

Conversely, the larger throttle plate will exaggerate tip-in, making smaller throttle excursions seem to produce more 'power' during take offs from the stop.

 

You calculated the cross sectional area, you may as well make it complete: Do the stock 50mm, and popular 60 and 65mm throttle plates as well and reveal to the unitiated the wonders of cross sectional area and throttle plate angle percentage delta change!

[evil_datto]

Alrighty,

 

L28E 50mm Single butterfly TB:

Butterfly area = 1963.5mm2

 

60mm Single butterfly TB:

Butterfly area = 2827.4mm2

 

65mm Single butterfly TB:

Butterfly area = 3318.3mm2

 

And the manifold & port sizes.. if it matters.

L28 manifold runner size: 30mm * 6

Total area = 4241.1mm2

 

L28 head intake port size: 34mm * 6

Total area = 5447.5mm2

[Daeron]

So a pair of these twin blade bodies would be more than enough breathing for a good, hi-po motor, AND it would make drivability much nicer if you had, say, an SU manifold altered to use fuel injectors, and aforementioned pair of siamese throttles. (Nicer compared to "some huge by large affair" that only has max HP in mind.)

 

 

This makes me have ideas about a plenum to toss onto this setup that I don't want to talk about for fear of being beaten to the punch. I've already said too much.

[Tony D]

Either I missed the earlier post showing the 50mm Stocker Cross section...or someone edited it to include it afterwards...

 

That shows the 50mm unit is considerably larger cross-sectionally than the smaller pairs. This tends towards the 'sport feel' of the Earlier Cars versus the JDM later version ZX's with more of a GT Tuned Feel (or a Cedric/Gloria for that matter.)

 

Strong tip-in response makes for a more sporty feel and the perception that there is more power there than there really is!

[kolonelklink87]

L28 NAPS Z Twin Butterfly: (From memory, It's in the car atm.) First butterfly = 32mm, Second = 35mm

First butterfly area = 804.2mm2

Second butterfly area = 962.1 mm2

Total area = 1766.3mm2

 

And the P65 intake runners diamater is 27mm (572.5mm2) each. The Y70 head is either 29-30mm2. I'll take a look later.

 

If the normal L28 TB butterfly's are 50mm, then it's 1963.5mm2.

 

I hate to throw my hat in the ring here but you might wanna recheck your measurement on the naps TB.

either your memory decieves you or there is yet anther TB version... i've been down this road before!

I have in my hand a twin throttle TB with a 40mm and 38mm butterfly. This makes sense because the TB mouth on the NAPS manifold is 40x80mm (thats 3000mm2 after you subtract the round edges) and the two butterflies fit neatly in here with a 2mm divider between them!!

 

The total butterfly area for the TB is 2390.8mm2 and thus outflows the stock 50mm. The upside of the naps manifold is that the mouth also outflows the 60mm TB so no porting is required if you use an adaptor plate.

 

I was using the naps TB as a step up from the stocker before adding my 60mm.... cedrics not so slow now?

 

-pete

[evil_datto]

I had all of this info measured up & saved on my comp, but of course Murphy & his Law bitch slapped me hard - I lost everything in a hard drive crash. If I can be bothered getting out into the garage today, I'll take it off and measure it up to see if I have a different one or just the same.

 

Now can someone tell me why I can't edit any of my posts? The option to edit seems to disappear shortly after I've posted...

[evil_datto]

Here we go!

So there may in fact be another twin version, because I went and checked my TB on the car at the moment.

It is two similar 'medium' sized butterflies, and although the TB was on the car making it difficult to measure, I could swear it was 35mm & 32mm. The 35mm looked smaller than the 40mm butterfly on the 40/25 I have.

 

Is it possible your NAPS TB is a turbo TB?

[kolonelklink87]

Is it possible your NAPS TB is a turbo TB?

 

*shrugs* could be... it came on a manifold without naps markings but the same layout (where it would say "naps efi" etc there is just blank space). other than that i have no history on it as it was an evilbay unit picked up by my old man in the country and mailed down to me.

 

*edit* I wonder if your manifold TB mouth is smaller too?

[evil_datto]

The manifold mouth matches fairly closely, so it could be smaller than yours.

I measured it properly and it's definitely 35mm on the top butterfly.

[kolonelklink87]

interesting... this may somehwat explain why my experiences with the manifold and twin throttle were by the whole greater than what appeared to be the consensus in the literature.... hmmm... v. curious about that TB mouth measurement. There's a 13mm difference to be acounted for between the reported TB's and the mouth apperture... thats alot of meat to hide

 

*edit* I'm sure OzCon must be lurking somewhere in the background of this post... I wonder what the throttle on that p65 turned out to be? P.s. I need to chat with you... I got into med at Usyd and have a plethora of l24 parts i can deliver to you at request (have crane and ute now... big couple of weeks lol)

[Daeron]

Wow. What a bounty of bodies!!!

[evil_datto]

JDM for the win eh.

All these other goodies make up for our lack of L28 turbos... almost.

[ozconnection]

interesting... this may somehwat explain why my experiences with the manifold and twin throttle were by the whole greater than what appeared to be the consensus in the literature.... hmmm... v. curious about that TB mouth measurement. There's a 13mm difference to be acounted for between the reported TB's and the mouth apperture... thats alot of meat to hide

 

*edit* I'm sure OzCon must be lurking somewhere in the background of this post... I wonder what the throttle on that p65 turned out to be? P.s. I need to chat with you... I got into med at Usyd and have a plethora of l24 parts i can deliver to you at request (have crane and ute now... big couple of weeks lol)

 

Here I am!!

 

Well done on your successes PK!! I will talk with you soon about all that 'stuff'. Cheers.

 

That P65 throttle body is what was described earlier, I did throw on a mike and it measured approx. 32mm primary, 34mm secondary.

 

Everything could be slabbed though, the thickness of the throttle blades and the shaft, screws et al are far from streamlined. CFM increases wouldn't be hard at all with some time and effort. Also, on full throttle, there could be at least 5 degrees more opening available on the secondary side. (The linkages fall short from opening it 100% unfortunately.) Work here could get some more throttle and thus more cfm.

 

Worth it? Depends on what you want really but Tony D was right. Great to rest your foot on the throttle just before the secondaries open, knowing exactly where you are, primed and ready for that extra something when you push the throttle further to the floor. Great vacuum in the manifold for econ. when cruising around on the primary only. I like that.

 

Cheers!

[evil_datto]

ozconnection, Could you get a picture of this TB & the TB mouth? interested if it's similar/the same as mine.

[Tony D]

Now... about increasing that secondary bore size to 48-50mm with that dinky primary...

 

All the parts exist, but is the body capable of taking that bore. That is what we all REALLY want: that dinky primary body for 85% of our driving. Do you guys realize how big a cam you could run and still get a decent MAP signal because of the small incremental changes from that primary barrel? Tuning would be a snap and the fuel economy would be FAR better than the same setup with a 60 or 65mm throttlebody, simply due to the resolution you get at partial throttle.

 

It's why I've eyed these for some time. I want the smallest primary body, with the largest secondary possible. For a turbo car this would really be ideal! For a heavily cammed car it would be even better...

 

Anybody remember the Dodge Thermoquads with the miniscule primary bores and then twin 2"+ secondaries? I put that intake and carb on a Dart with a 318 and got BETTER gas mileage than with the original 2bbl (which had FAR larger primary barrels!) Same forces are work... You want resolution for 85% of the driving you do. The rest of the time you want least restriction to flow possible. These dinky primaries do it...we just need a bigger secondary for when the WOT urge arises.