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Discussion Starter · #1 ·
Re: Great Info, except..

Tim,

All that info is great, I really appreciate the post. It all makes a lot of sense, too. Yet, there is one detail you mention that ironically supports my statements about HP. The internet Z car club's tech sheet states it exactly as I did (except that I didn't realize the difference you mentioned for the '81-83 models) 280Z = 149BHP and 280ZX = 135BHP. There is a spec for the '82 ZX which shows 145BHP. So, what you're saying must've changed the rating. But that's still 4 hp less than the 280. Why? Is their GOSPEL WRONG? Go look at it again-- the 280Z is not rated at 135bhp.
I still maintain, as in the first post, that the engines ('75-81)are mostly identical, it's the power steering and other bolt-ons (is there a smog pump?) that are robbing horsepower. If not, what is the difference? Did they lower the compression ratio further in the '79-'81?

Give me some feedback. I'm a detail freak and want to get to the bottom of this. It's a stupid thing, but there has to be a logical answer and it'll drive me crazy to think somebody's right or wrong without understanding the reasons.

Thanks.

Waiting to be slammed,

Matt
 

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Re: Great Info, except..

Guy's, here's the info I have. It's from Chiltons and is the same as most of the other info I've read.
70-73 151hp 8.8:1 cpmpression
74 162hp 8.8:1 compression
75-78 170hp 8.3:1 compression
79 135bhp 8.3:1 compression
80 132bhp 8.3:1 compression
81-83 (non-turbo) 145 bhp 8.8:1 compression
84-86 (non-turbo) 160bhp 9.0:1 compression

Hope this helps.

rbest
 

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Re: Great Info, except..

Matt,
First, we are not here to slam you, no matter how much of a detail freak you are.
Let me start by saying I cannot quote you hp figures, for I don't bench race. But what I can share with you is the timeline of the engines, and how it affected the power.
I will start with the first 280 motors. They began with the N42 head, and quickly switched to the N47 head. These motors had a dish piston, and a compression ration in the 8's. They remained that way until, I want to say 81, when the P series head was introduced, ie the P-79 on the non-turbo motor. There are two things to note, one, the P-series heads had a significantly larger combustion chamber than previous, ie 53.4cc's vs about 47 cc's. To make up for the larger combustion chamber, flat-top pistons were substituted for the dished ones, and that actually raised the compression ratio from about 8.3 to 8.8:1. So there was a corresponding hp jump. The first 280 motors up through 81 should have about 135-39 hp. It was with the p-series motors that the hp was 149, and for the first time, faster than the original z. The hp stayed the same until the end of the 280ZX run in 83. If you are looking for a cheap performance buildup, the flat-top motor coupled with a good head, either a n-42 or a modified p-79, yields an excellent combo. there is a whole lot of info out there on the heads, and not all of it is accurate. I have taken several expert sources and hope to put it on my head page when it is finished being re-written,(this is not to say i am the end all be all source, for i am most certainly not, but just to warn people to be wary about what they find on the net, ie don't assume it is gospel).
And the 170 some hp rating that rbest has from chiltons, it must be a gross rating, for no z or zx motor had that much net hp until the turbo.
-Bob Hanvey
 

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Re: Great Info, except..

> Guy's, here's the info I have. It's from
> Chiltons and is the same as most of the
> other info I've read.
> 70-73 151hp 8.8:1 cpmpression
> 74 162hp 8.8:1 compression
> 75-78 170hp 8.3:1 compression
> 79 135bhp 8.3:1 compression
> 80 132bhp 8.3:1 compression
> 81-83 (non-turbo) 145 bhp 8.8:1 compression
> 84-86 (non-turbo) 160bhp 9.0:1 compression

Here is what I have compiled over the years from several sources:

Car: 240z
Year: 70-73
Gross HP=151
Net HP=121

Car: 260z
Year: 74
Gross HP=162
Net HP=129

Car: 280z
Year: 75-79
Gross HP=170
Net HP=135

Car: 280zx
Year: 79-80
Gross HP=170
Net HP=135

Car: 280zx
Year: 81-83
Gross HP=180
Net HP=145

Car: 280zxt
Year: 81-83
Gross HP=207
Net HP=180

The NET rating was introduced in 1979, ushered in by the FEDS who decided that GROSS ratings were not an acurate rating and were subject to wild inflations brought on by the 60s HP wars.

Note that some NET ratings include AC compressor and PS pump loads on the engine. These are pretty worthless ratings for comparison reasons and I believe that the common HP ratings for the 81-83 280zx include AC load.

Also, the L28 was unchanged from 75-80, so any change in stated HP from 75-80 is not correct and probably a result of the GROSS--->NET switch.
 

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Yes, the 170 is gross.

Yes Bob, the 170 is gross. As noted the net figures are identified by bhp as aposed to hp. I hope this is not confusing to people.

The change in horsepower rating has caused too much confusion. In '79 they changed to net ratings, as you state, and too many people think the zx's had much less power and it is just not the case. I've seen the same argument between mustang people like with the 335hp of a '69 429 cobra and (only) 260bhp (net) of the new cobra. The '99 Cobra is much faster despite the apparent lower horsepower, and smaller engine! The '99 is not lower on power, though. And even has a much higher power to weight ratio even though it's only 200lbs lighter.

I'm really rambling now and I wasn't even in on the beginning of this so I don't know where I'm going. There's much more than simply HP numbers. How about torque, gear ratios, and even aerodynamics. The early z's were certainly not the best at cheating the wind.

OK I'm done.

Randy Best
 

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Discussion Starter · #6 ·
Re: John Travolta would've drove a '78 (not short)

> Yes Bob, the 170 is gross. As noted the net
> figures are identified by bhp as aposed to
> hp. I hope this is not confusing to people.

> The change in horsepower rating has caused
> too much confusion. In '79 they changed to
> net ratings, as you state, and too many
> people think the zx's had much less power
> and it is just not the case. I've seen the
> same argument between mustang people like
> with the 335hp of a '69 429 cobra and (only)
> 260bhp (net) of the new cobra. The '99 Cobra
> is much faster despite the apparent lower
> horsepower, and smaller engine! The '99 is
> not lower on power, though. And even has a
> much higher power to weight ratio even
> though it's only 200lbs lighter.

> I'm really rambling now and I wasn't even in
> on the beginning of this so I don't know
> where I'm going. There's much more than
> simply HP numbers. How about torque, gear
> ratios, and even aerodynamics. The early z's
> were certainly not the best at cheating the
> wind.

> OK I'm done.

> Randy Best

Thanks for all the intelligent feedback, guys/gals. So many efficient cerebral cells going to waste on such trivial concerns, 10 hp. Did you know that Vanna's first letter turned was a T. Now you'll be stuck with that stupid piece of history, like I am.

Ok, I learned that the later ZX's had a little higher compression, flat top pistons, slightly different head combustion chamber, thus upping the HP 10+. Did I miss anything? Sounds real logical, too.

As for the '75-'81 models, we're talking virtually the same engine HP (according to smart (read-- those that write with conviction and authority) respondants on this forum). I like you guys. Tell it like it is.

As for me, there never really was an issue of understanding the net vs. gross ratings. All the published sources I was refering to were using the net rating. I'd still like to see some authoritative spec. reference that shows the Z at 135bhp. If anyone can point me to it, I might send you a cool e-mail sometime.

Evan B., your post was close, but the Chilton states 170hp, which we already know--it's stamped on the engine plate from the factory. What I don't understand is why that's converted to 135bhp by some and 145-149bhp by others.

Oh, I've got it!! Perhaps it's a conspiracy by the 1st generation Z purists? They published the books and specs that I've seen and just want the ZXrs to feel like they were ripped. Since I own a '78, I would've helped with this conspiracy, given the chance. So whether a conspiracy, lunacy, or just outright lies, I'll just believe it and feel better about my car-- which for us in the male gender means I'll feel better about myself, too. Funny how that works.

The bottom line, We have to accept that engineering in the 70s (read-- 75-78) was superior to all later-- polyester proves it. Who needs rear disk brakes, anyway? I could dance way better in my Angel Flights in '77. Sorry to those of you too young to remember Saturday Night Fever, Welcome Back Cotter(sp). and our beloved, pencil neck John Travolta. He would've drove a '78 Z, if it wasn't for that **** Convertible XKE.

One more theory on this hp mystery: Perhaps it's like energy and the pyrmids. The early body style was so superior, that it energized the motor to ultimately produce 10 more horses. I think polyester has a similar effect.

Matt
 

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Re: John Travolta would've drove a '78 (not short)

> Thanks for all the intelligent feedback,
> guys/gals. So many efficient cerebral cells
> going to waste on such trivial concerns, 10
> hp. Did you know that Vanna's first letter
> turned was a T. Now you'll be
> stuck with that stupid piece of history,
> like I am.

> Ok, I learned that the later ZX's had a
> little higher compression, flat top pistons,
> slightly different head combustion chamber,
> thus upping the HP 10+. Did I miss anything?
> Sounds real logical, too.

> As for the '75-'81 models, we're talking
> virtually the same engine HP (according to
> smart (read-- those that write with
> conviction and authority) respondants on
> this forum). I like you guys. Tell it like
> it is.

> As for me, there never really was an issue
> of understanding the net vs. gross ratings.
> All the published sources I was refering to
> were using the net rating. I'd still like to
> see some authoritative spec.
> reference that shows the Z at 135bhp. If
> anyone can point me to it, I might send you
> a cool e-mail sometime.

> Evan B., your post was close, but the
> Chilton states 170hp, which we already
> know--it's stamped on the engine plate from
> the factory. What I don't understand is why
> that's converted to 135bhp by some and
> 145-149bhp by others.

> Oh, I've got it!! Perhaps it's a conspiracy
> by the 1st generation Z purists? They
> published the books and specs that I've seen
> and just want the ZXrs to feel like they
> were ripped. Since I own a '78, I would've
> helped with this conspiracy, given the
> chance. So whether a conspiracy, lunacy, or
> just outright lies, I'll just believe it and
> feel better about my car-- which for us in
> the male gender means I'll feel better about
> myself, too. Funny how that works.

> The bottom line, We have to accept that
> engineering in the 70s (read-- 75-78) was
> superior to all later-- polyester proves it.
> Who needs rear disk brakes, anyway? I could
> dance way better in my Angel Flights in '77.
> Sorry to those of you too young to remember
> Saturday Night Fever, Welcome Back
> Cotter(sp). and our beloved, pencil neck
> John Travolta. He would've drove a '78 Z, if
> it wasn't for that **** Convertible XKE.

> One more theory on this hp mystery: Perhaps
> it's like energy and the pyrmids. The early
> body style was so superior, that it
> energized the motor to ultimately produce 10
> more horses. I think polyester has a similar
> effect.

> Matt

Matt, there is no mystery. I strapped my '78 to a dyno, and wouldn't you know, there it was... approx. 135 flywheel hp!!!
 

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Re: Great Info, except..

> Guy's, here's the info I have. It's from
> Chiltons and is the same as most of the
> other info I've read.
> 70-73 151hp 8.8:1 cpmpression
> 74 162hp 8.8:1 compression
> 75-78 170hp 8.3:1 compression
> 79 135bhp 8.3:1 compression
> 80 132bhp 8.3:1 compression
> 81-83 (non-turbo) 145 bhp 8.8:1 compression
> 84-86 (non-turbo) 160bhp 9.0:1 compression

> Hope this helps.

> rbest

Hey guys, have not visited the forum for a while, but the numbers for the 70-73 have to be suspect and here is why (not slamming anyone but Chilton, in thiscase):

The early cars 70 through part of 71 had E31 heads on them (I have one) and the later had E88 (I have one of these too). The E31 is a much smaller combustion chamber and the valves are smaller too than the E88. Therefore the compression cannot be the same (and it is not, the E31 is higher). As for HP, maybe the lower compression combined with a bigger valve added up to substantially similar hp numbers (at least within the test tolerance). No doubt that Nissan did not publish two different hp ratings that I have ever seen for the 70 - 73 years. No question that the E31 is snappier off the line, at least as installed in my car.

Ray
 
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