Key differences between the American and European 260z

[Langheck]

My question that I've been researching is what differences are there that make a 1974 260z (mine is early) different from the European 260 in terms of its motor? I know that from a broad view the key differences are the reduced compression (from the altered '74 E88 head?) and flat top emissions-grade carbs, but what changes were there from the 139hp motor to the hotter 165hp?My goal, if possible, is to take my stock motor and convert it to match or exceed a euro-spec engine in terms of performance. See how far I can push an L26 without swapping or making a 2.4 or 2.8 motor. Any help or info on the subject would be very much appreciated

[LeonV]

My question that I've been researching is what differences are there that make a 1974 260z (mine is early) different from the European 260 in terms of its motor? I know that from a broad view the key differences are the reduced compression (from the altered '74 E88 head?) and flat top emissions-grade carbs, but what changes were there from the 139hp motor to the hotter 165hp?My goal, if possible, is to take my stock motor and convert it to match or exceed a euro-spec engine in terms of performance. See how far I can push an L26 without swapping or making a 2.4 or 2.8 motor. Any help or info on the subject would be very much appreciated

There is no 139hp and 165hp motor, I bet you're comparing power tested under different rating systems (SAE net, gross, etc.). I'd imagine the performance differences being very slim.

[Captain Obvious]

I was expecting you to be asking about differences in the keys used for the American and European 260z.

So for what you really meant... If you're that serious about it, you might consider making sure everything is in tip-top shape and then get a dyno run done to establish a baseline. You might be surprised by what you are getting out of your current engine.

[Langheck]

Yes, I should have stated 'B'HP. My mistake, sorry to mix things up. The book here states the Kw output of all markets of the 260 being 123. Also an equal rating for PS. However, BHP is what changes between the markets. Could this be explained by the shift of manufacturers advertising cars with net horsepower ratings instead of gross HP? Was it the only the US that had only shifted to this rating system at the time?

And where would this power have been lost? Obviously some variations between markets point to the flat-top hitachi carbs, emissions equipment, and overall weight of the car being moved. But could the compression ratio or ignition timing changes hinder an American market car compared to other market 260Zs, or would these alterations to run unleaded petrol have been universal?

Just really curious as to why the US 260z are so undesirable and viewed as weak. I am just looking to make the most of the L26's potential and have been confused by all the scattered and varying information about the car and its setup.

[LeonV]

Yes, I should have stated 'B'HP. My mistake, sorry to mix things up. The book here states the Kw output of all markets of the 260 being 123. Also an equal rating for PS. However, BHP is what changes between the markets. Could this be explained by the shift of manufacturers advertising cars with net horsepower ratings instead of gross HP? Was it the only the US that had only shifted to this rating system at the time?

And where would this power have been lost? Obviously some variations between markets point to the flat-top hitachi carbs, emissions equipment, and overall weight of the car being moved. But could the compression ratio or ignition timing changes hinder an American market car compared to other market 260Zs, or would these alterations to run unleaded petrol have been universal?

Just really curious as to why the US 260z are so undesirable and viewed as weak. I am just looking to make the most of the L26's potential and have been confused by all the scattered and varying information about the car and its setup.

There are no appreciable power differences! Yes, it's the difference between SAE gross and net. Whatever book you referenced is right, all of them had the same power output, does it matter at this point what the rated BHP is? There is no lost power to make up for. The L26 has more displacement than the L24, and thus has more power than the L24.

There are SO many misconceptions about the 260Z, many perpetuated by media (i.e. magazines, etc.) or a misunderstanding by the reader of what the media was saying.

I LOVE that the 260Z is viewed as "weak and undesirable"! That means I can find them cheaper even though I consider them to be a better car (carbs can be easily swapped out although I wish there was a parts market for flat tops). They're a fun and quirky car to own since it was a 1-year-only model in the US and it's fun to figure out all the 260Z-specific aspects. Shhh, don't tell anyone!

[HS30-H]

There are SO many misconceptions about the 260Z, many perpetuated by media (i.e. magazines, etc.) or a misunderstanding by the reader of what the media was saying.

There are misconceptions about everything, though. Try telling people that "240Z" means more than one thing and they look at you funny. Same with "260Z". There's '260Zs' and there's '260Zs'....

There certainly were basic power differences for what appeared to be similar engines, depending on the period and the market. It may not be as much as the OP hoped - or as little as you think - but for sure there were differences in camshafts, compression ratios, ignition timing / timing curves and carburation, and that's before we start talking about any anti-pollution gear being hung on them.

Like-for-like, year-for-year, I think you'll find that the 'Euro' market models will always have had more power than north American market models. Maybe not much, but worth noting.

[LeonV]

There are misconceptions about everything, though. Try telling people that "240Z" means more than one thing and they look at you funny. Same with "260Z". There's '260Zs' and there's '260Zs'....

There certainly were basic power differences for what appeared to be similar engines, depending on the period and the market. It may not be as much as the OP hoped - or as little as you think - but for sure there were differences in camshafts, compression ratios, ignition timing / timing curves and carburation, and that's before we start talking about any anti-pollution gear being hung on them.

Like-for-like, year-for-year, I think you'll find that the 'Euro' market models will always have had more power than north American market models. Maybe not much, but worth noting.

Of course, however, the 260Z carries a certain mysterious stigma, at least in the US.

Hence why I said "appreciable" differences. I'm sure there were minor spark timing curve alterations, slight differences in compression, etc. People get caught up with "emissions" equipment, but as is usually the case, that equipment does little to nothing to hurt power (and sometimes helps, i.e. EGR). Sure give or take a few hp, but I'd surmise that there isn't a seat-of-the-pants difference in driving the two.

Point being, the difference between the two isn't anywhere near 26hp!

I also greatly enjoy the irony of people lambasting the US 260Z, yet the 260Z cam and intake are widely renowned as the hi-po factory stuff!

[Captain Obvious]

I wish there was a parts market for flat tops

Haha! You looking for something specific? :pirate:

[Carl Beck]

Hence why I said "appreciable" differences. I'm sure there were minor spark timing curve alterations, slight differences in compression, etc. People get caught up with "emissions" equipment, but as is usually the case, that equipment does little to nothing to hurt power (and sometimes helps, i.e. EGR). Sure give or take a few hp, but I'd surmise that there isn't a seat-of-the-pants difference in driving the two.

Point being, the difference between the two isn't anywhere near 26hp!

Hi LeonV:

If you look at the Road Tests from the time {relative data at best} - Pounds per HP and 0-60 times - it seems quite possible that the North America L26, tuned to meet our Emissions Standards for 74 - lost 26 HP. On top of that our Fat Bumpers and other "safety" equipment added about 200 lbs to our 260Z vs the UK model. Any way I look at it - 2 seconds 0-60 mph is a pretty great seat of the pants difference.

A Snap Shot from some of the Magazine Road Tests of the time:

1970 240Z 150 HP - Curb Weight 2355 lbs - Pounds per HP 15.7

0-60 mph 8.2 sec. 1/4 mile 15.5 sec. at 87mph

1974 260Z {North America} 139 HP - Curb Weight 2665 lbs - Pounds per HP 19.2

0-60 mph 10.3 sec. 1/4 mile 17.9 sec. at 79 mph

1974 260Z {UK} 162 HP - Curb Weight 2425 lbs - Pounds per HP 15

0-60 mph 8.2

As one can see the UK model for example had the performance of our 240Z's.. Adding 200 lbs doesn't add 2 seconds 0-60 - so there had to be a significant HP loss as well. That HP loss was attributable to configuring and tuning our L26 engines to meet our Emissions Standards. Look at the difference between Euro Spec 74 Porsche 911's and US Spec. 911's and you will see pretty much the same story. In the early days of meeting our Emissions standards it cost significant HP here. I do agree that once the technology caught up with Emissions standards - they resulted in far better performing engines.. but that would be years after 1974.

Also - I believe that there is a difference between a car being "undesirable", and a car being "less desirable" than an earlier model. I don't believe that the 260Z's are considered undesirable here.

I think it is easy to understand why the US 260Z is less desirable than the lighter, faster 240Z's. Nonetheless, clean original early 260Z's are still very desirable. It does however COST MONEY to swap out the bumpers and Carbs, re-curve the distributors etc etc ... So that cost comes off the initial price of the car - so Yes the 260Z's here sell for less to start with.. Nonetheless as you point out they also offer several improvements over the 240Z's..

FWIW,

Carl B.

[Carl Beck]

My question that I've been researching is what differences are there that make a 1974 260z (mine is early) different from the European 260 in terms of its motor? I know that from a broad view the key differences are the reduced compression (from the altered '74 E88 head?) and flat top emissions-grade carbs, but what changes were there from the 139hp motor to the hotter 165hp?My goal, if possible, is to take my stock motor and convert it to match or exceed a euro-spec engine in terms of performance. See how far I can push an L26 without swapping or making a 2.4 or 2.8 motor. Any help or info on the subject would be very much appreciated

I think you have more or less answered your own question. It is pretty easy to pick up 23 HP {162-139} if you bump up the compression ratio, set the ignition timing and distributor timing curve to a more performance oriented setting, and use carb's that allow more adjustability for air/fuel ratio's. Especially when the HP was there to begin with - and was "tuned out" or "traded-off" to meet our emissions standards.

Years ago - when the Nissan Competition Parts Dept. was in existance for example - you could order "Euro Spec." pistons. They had a 2cc platform on top of the flat top pistons - which in effect reduced combustion chamber volume by 2cc's.

So ... Scrap your 74 E88 head {47.8 cc combustion chambers} - and replace it with a 71/72 E88 {44.7cc combustion chamber}or better a 75 N42 head {it comes with the larger valves}. Add the larger intake/exhaust valves from the 75/77 280Z's to the E88. Use the Euro Spec. pistons. That will raise your compression ratio from 8.8 to 9.5. Use a 71/72 distributor and you'll have a good advance curve to start with, or have your 260Z distributor re-worked to get a good advance curve. Add a mild cam and dump the Air Injection and other emissions gear.. and you'll easily pick up 25 to 30 HP. If you can't find a set of the Euro Spec. pistons you can just mill the 71/72 E88 head to reduce combustion chamber volume.

Of course you have to have a good valve job, the valves need to be unshrouded and with hardened seats - etc. etc All of this has to be on top of a good long block {good rings, bearings etc}.

Have all the parts on hand, the head back from the machine shop and a good set of S.U.s - and a day in the garage you can bolt everything on.. After that you can work on Weight Reduction..

FWIW,

Carl B.

[LeonV]

Hi LeonV:

If you look at the Road Tests from the time {relative data at best} - Pounds per HP and 0-60 times - it seems quite possible that the North America L26, tuned to meet our Emissions Standards for 74 - lost 26 HP. On top of that our Fat Bumpers and other "safety" equipment added about 200 lbs to our 260Z vs the UK model. Any way I look at it - 2 seconds 0-60 mph is a pretty great seat of the pants difference.

A Snap Shot from some of the Magazine Road Tests of the time:

1970 240Z 150 HP - Curb Weight 2355 lbs - Pounds per HP 15.7

0-60 mph 8.2 sec. 1/4 mile 15.5 sec. at 87mph

1974 260Z {North America} 139 HP - Curb Weight 2665 lbs - Pounds per HP 19.2

0-60 mph 10.3 sec. 1/4 mile 17.9 sec. at 79 mph

1974 260Z {UK} 162 HP - Curb Weight 2425 lbs - Pounds per HP 15

0-60 mph 8.2

As one can see the UK model for example had the performance of our 240Z's.. Adding 200 lbs doesn't add 2 seconds 0-60 - so there had to be a significant HP loss as well. That HP loss was attributable to configuring and tuning our L26 engines to meet our Emissions Standards. Look at the difference between Euro Spec 74 Porsche 911's and US Spec. 911's and you will see pretty much the same story. In the early days of meeting our Emissions standards it cost significant HP here. I do agree that once the technology caught up with Emissions standards - they resulted in far better performing engines.. but that would be years after 1974.

Also - I believe that there is a difference between a car being "undesirable", and a car being "less desirable" than an earlier model. I don't believe that the 260Z's are considered undesirable here.

I think it is easy to understand why the US 260Z is less desirable than the lighter, faster 240Z's. Nonetheless, clean original early 260Z's are still very desirable. It does however COST MONEY to swap out the bumpers and Carbs, re-curve the distributors etc etc ... So that cost comes off the initial price of the car - so Yes the 260Z's here sell for less to start with.. Nonetheless as you point out they also offer several improvements over the 240Z's..

FWIW,

Carl B.

Carl,

This is exactly what I was talking about, people quoting MEDIA figures as scientific evidence. Also, we're not talking Porsches, or Chevys, or anything else besides Z-cars.

Can you explain why my US-market 260Z, and all others I've seen, say "162hp" on the engine plate?

I also doubt my early 260Z weighs that much much more than a 240Z. The only real differences between the two are more heavy duty bumpers, bumper shocks, some extra wires and a rear ARB. I've yet to weigh those parts to see what they add but I can to it today, plus I've got early 240Z bumpers to compare with. The 260Z definitely weighs more than an earlier 240Z, but as you saw, it won't make a huge difference in performance.

I completely disagree that "emissions equipment" took off 26hp. What emissions equipment are we talking about here?

• EGR only affects part-throttle performance (and actually makes it better).
  
• The AIR system was shared with 240Zs.
  
• EVAP equipment has no effect on performance.
  
• PCV is on all Z's.
  
• Throttle opener solenoids are on both models and don't affect power.
  

So, we see that the ancillary emissions equipment has nothing to do with it.

How about engine changes?

• Engine displacement increased by 0.2L in the 260Z.
  
• Compression ratio might have dropped a tiny bit compared to the E31 headed 240Zs, but it's the same as later 240Zs (which were rated at 151hp) at 8.8:1.
  
• Speaking of carbs, the funny thing is that the flat-tops "allow more adjustability for air/fuel ratio's (sic)," as you put it. Flat tops have separate idle and WOT circuits, unlike the round-tops.
  
• Spark timing curves did change. The 240Z had 17deg initial timing and 12deg of centrifugal advance for 29deg of total timing at WOT. The 260Z had 7deg of initial timing but a whopping 26deg of centrifugal advance, making for 33deg total at WOT. Thus, the 260Z had a more aggressive timing profile!
  
• The 260Z cam is more aggressive because of an increase in displacement. The cam did not detract from performance.
  
• The 260Z intake is said to flow and distribute the mixture better than the 240Z manifolds. I have not tested this. However, both the 260Z cam and intake are sought after by guys wanting to use stock parts to make their 240Z perform better.
  

Do you see anything I don't see in terms of losing 26hp? I sure as heck don't! As far as I'm concerned and been able to determine, the US 260Z had 11 more horsepower than the 240Z.

References:

1. 1972 240Z FSM
   
2. 1974 260Z FSM
   

[Carl Beck]

Carl,

This is exactly what I was talking about, people quoting MEDIA figures as scientific evidence. Also, we're not talking Porsches, or Chevys, or anything else besides Z-cars.

Hi LeonV:

To be fair - I did not quote the data as scientific evidence. I clearly labeled it as "relative data" - not ordinal. Road Test data from the auto magazines is all we have that reflects more or less common performance measures - 0-60, 1/4 mile etc.

From your comments, I believe you understood my point - that being that an additional 200 lbs - the difference between the UK and NA cars - couldn't account for a 2 second difference 0-60. The Pounds per HP numbers also seem to fall in line with the differences in performance.

Can you explain why my US-market 260Z, and all others I've seen, say "162hp" on the engine plate?

I have about 10 RLS30 engine plates - but they all range only up to the 40,000 VIN range - they all say 162HP. I did not find a HP Rating in my 74 FSM. So I don't think there is an explanation needed for that. Rather a source or explanation is needed for the 139 HP rating given in the Road Tests.

I also doubt my early 260Z weighs that much much more than a 240Z. The only real differences between the two are more heavy duty bumpers, bumper shocks, some extra wires and a rear ARB. I've yet to weigh those parts to see what they add but I can to it today, plus I've got early 240Z bumpers to compare with. The 260Z definitely weighs more than an earlier 240Z, but as you saw, it won't make a huge difference in performance.

You also have to add the additional weight of the 260Z doors with Side Impact beams, the reinforced sub-frames and the additional heat/sound insulation. I've never weighed a 260Z door, but if I pick up an S30 door I can tell pretty quickly if it is from an early or late 240Z or a 260/280Z.

I I completely disagree that "emissions equipment" took off 26hp. What emissions equipment are we talking about here?

I did not say emissions equipment. I attributed it to "configuring and tuning" our L26's to meet our emissions standards. The combustion chamber design, fixing fuel/air ratio's to meet the emission standards, and ignition timing.

Do you see anything I don't see in terms of losing 26hp? I sure as heck don't! As far as I'm concerned and been able to determine, the US 260Z had 11 more horsepower than the 240Z.

No I don't see anything, other than setting the engine up to meet the emissions standards. With 11 more HP - that should offset the additional weight of our 260Z's - - but then other than a loss of HP what else accounts for the significant drop in performance - stock for stock.

FWIW,

Carl B.