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Discussion Starter #1
Well, here's the spec on the current engine in my '72 240Z.

Block: '77 280Z
Crank: Stock 79mm Balanced to flywheel and pulley.
Rods: Stock 280Z Balanced
Pistons: 86mm Balanced
Rings: Stock Nissan (New)
Head: '72 E88 shaved .050 Match Ported to intake and valve unshrouding and minor bowl porting. Competition 3-angle valve job, chrome moly seats, heavy duty springs. Semi-polished surface.
Head Gasket: Stock (1.2mm thk)
Compression ratio 9.3:1
Cam: L7 NISMO .475/270 duration
(Planning on .445/290 duration)
Intake: Cannon long manifold, fully port matched and semi-polished.
Carbs: Triple 45mm Webers with 36mm chokes and air horns (36mm chokes are HUGE)
Ignition: Pertronix igniter unit with MSD-6AL
(upgrading to magnecor wires soon)
Headers: 6-2 NISMO 1.625 primaries
Exhaust: 2.5 custom made with Dynomax straight through muffler

Clutch: Centerforce II
Transmission: Stock '78 280Z 5spd
Differential: Stock R180 3.364:1

This engine runs strong, and pulls to 6500rpm. Power begins at 3500 and climbs until 6500rpm. The reason I have so much top end, is that I have such huge venturis. This engine can flow alot of air/fuel. But, the problem with such big carbs is the main circuit (carb) doesn't kick in until past 3000rpm, so anything below that really bogs the engine down. There just isn't enough airflow to suck gas out of the carb. It takes alot of practice to drive around town. But, once 3000 is hit, it pours on the power, and doesn't quit. My main problem is drivetrain. The gearing is way too low for this setup with the R180. And, my diff mount is ripped and u-joints are worn. I'm going to replace all that stuff while on vacation toward the end of Dec.
I don't have dyno figures for this engine, but compared to others similar to it, it is estimated at 220-240hp. My best run at Sears Point was a [email protected] I'm expecting at least high 13's, depending on what ratio R200 I use, and after fixing all the broken parts. By the way, I didn't really build this car for drag racing. It's built for road racing. It's lowered into the weeds and has 225/50/15 tires on 15x7 panasports all around. I can outhandle almost anything on the road today. People that ride with me are totally amazed at how fast I can take turns. The main comment people make to me is; My car would flip over if I took that turn like that!

P.S. The post below was a fictitios example. I just used numbers that closely relate to a Z engine, they were not exact numbers from a dyno run. I was just trying to show how gearing plays a role in when you shift, even though power drops off at a higher rpm. But, like I said, closer gearing would eliminate the need to rev so high, because the shift drop would not be so much. I would imagine a close ratio 5spd with 3.1L would be quite fast.

What are your specs??
240Dave
 

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Re: The specs on my engine for Chris and whoever e

> Well, here's the spec on the current engine
> in my '72 240Z.

> Block: '77 280Z
> Crank: Stock 79mm Balanced to flywheel and
> pulley.
> Rods: Stock 280Z Balanced
> Pistons: 86mm Balanced
> Rings: Stock Nissan (New)
> Head: '72 E88 shaved .050 Match Ported
> to intake and valve unshrouding and minor
> bowl porting. Competition 3-angle valve job,
> chrome moly seats, heavy duty springs.
> Semi-polished surface.
> Head Gasket: Stock (1.2mm thk)
> Compression ratio 9.3:1
> Cam: L7 NISMO .475/270 duration
> (Planning on .445/290 duration)
> Intake: Cannon long manifold, fully port
> matched and semi-polished.
> Carbs: Triple 45mm Webers with 36mm chokes
> and air horns (36mm chokes are HUGE)
> Ignition: Pertronix igniter unit with
> MSD-6AL
> (upgrading to magnecor wires soon)
> Headers: 6-2 NISMO 1.625 primaries
> Exhaust: 2.5 custom made with Dynomax
> straight through muffler

> Clutch: Centerforce II
> Transmission: Stock '78 280Z 5spd
> Differential: Stock R180 3.364:1

> This engine runs strong, and pulls to
> 6500rpm. Power begins at 3500 and climbs
> until 6500rpm. The reason I have so much top
> end, is that I have such huge venturis. This
> engine can flow alot of air/fuel. But, the
> problem with such big carbs is the main
> circuit (carb) doesn't kick in until past
> 3000rpm, so anything below that really bogs
> the engine down. There just isn't enough
> airflow to suck gas out of the carb. It
> takes alot of practice to drive around town.
> But, once 3000 is hit, it pours on the
> power, and doesn't quit. My main problem is
> drivetrain. The gearing is way too low for
> this setup with the R180. And, my diff mount
> is ripped and u-joints are worn. I'm going
> to replace all that stuff while on vacation
> toward the end of Dec.
> I don't have dyno figures for this engine,
> but compared to others similar to it, it is
> estimated at 220-240hp. My best run at Sears
> Point was a [email protected] I'm expecting at least
> high 13's, depending on what ratio R200 I
> use, and after fixing all the broken parts.
> By the way, I didn't really build this car
> for drag racing. It's built for road racing.
> It's lowered into the weeds and has
> 225/50/15 tires on 15x7 panasports all
> around. I can outhandle almost anything on
> the road today. People that ride with me are
> totally amazed at how fast I can take turns.
> The main comment people make to me is;
> My car would flip over if I took that
> turn like that!

> P.S. The post below was a fictitios example.
> I just used numbers that closely relate to a
> Z engine, they were not exact numbers from a
> dyno run. I was just trying to show how
> gearing plays a role in when you shift, even
> though power drops off at a higher rpm. But,
> like I said, closer gearing would eliminate
> the need to rev so high, because the shift
> drop would not be so much. I would imagine a
> close ratio 5spd with 3.1L would be quite
> fast.

> What are your specs??
> 240Dave

Sounds like you and Bob H(I think that's right.) are in the same boat. You both have similiar power curves and your power band begins about the same place. Do you think the power curve could be strengthened in the higher rpm by running a single four barrel setup? Motorsport sells a 4 barrel manifold, that you can put a Holley or Edelbrock carb on. A 600cfm Holley would be nice. They make one now that's very similiar to the 750 Double Pumper.

I've heard that the close ratio Nismo trannies provide an absolutly un-Godly 0-100mph time. I would bet that it is a valuable commodity on the track and a horrible detriment around town.

What's the ceiling compresion ratio that can be run safley on one of the 2.8's. My 3.1 sits at 10.6:1. Can the 2.8's do the same? What was stock from Nissan?

Sorry for all of the questions, but I'm finding more and more diffrences between 3.1 vs 2.8 and Fuel injection vs Carbed as we go.

Chris Behney
Redline Autosports
 

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Discussion Starter #3
Re: The specs on my engine for Chris and whoever e

> Sounds like you and Bob H(I think that's
> right.) are in the same boat. You both have
> similiar power curves and your power band
> begins about the same place. Do you think
> the power curve could be strengthened in the
> higher rpm by running a single four barrel
> setup? Motorsport sells a 4 barrel manifold,
> that you can put a Holley or Edelbrock carb
> on. A 600cfm Holley would be nice. They make
> one now that's very similiar to the 750
> Double Pumper.

Nope, the 4 barrel carb setup doesn't distribute fuel evenly on a straight six, and you will run into a lean condition. They may work fine when sitting atop a V8, but don't work well for a side induction straight six. Don't get this, stay with your fuel injection. Besides the fuel injection is working quite well if you're running in the 13's.
The only way you are going to strenghten the top end is to install a different cam, or upgrade the intake to independent runners. This would improve throttle response and provide more air for higher rpm. Maybe a 3 exhuast would help also. I'm looking into some 3 oval pipe for my center section, then I can run 3 pipe on a N/A. Talk about minimal restriction!!

> I've heard that the close ratio Nismo
> trannies provide an absolutly un-Godly
> 0-100mph time. I would bet that it is a
> valuable commodity on the track and a
> horrible detriment around town.

Well, lets do some math, and see what would happen. Using the example posted below:
Say you're torque curve is farily flat from 4000-5500 @210ft/lbs and falls to 200ft/lbs @6000. Therefore you don't want to drop below 4000 rpm, because you'll be below the peak torque. We'll just say shift at 6000 for both, and notice the difference.

Stock 280Z 5spd
1st: 3.321
2nd: 2.077
3rd: 1.308
4th: 1.000

2nd gear rpm = 6000 (2.077/3.321) = 3752rpm
2nd gear rpm = 6500 (2.077/3.321) = 4065rpm
6000 = poor shift point
6500 = better shift point
3rd gear rpm = 6000 (1.308/2.077) = 3778rpm
3rd gear rpm = 6500 (1.308/2.077) = 4093rpm
6000 = poor shift point
6500 = better shift point

NISMO Close-Ratio 5spd p/n 32010-N3130
1st: 2.906
2nd: 1.902
3rd: 1.308
4th: 1.000

2nd gear rpm = 6000 (1.902/2.906) = 3927rpm
2nd gear rpm = 6300 (1.902/2.906) = 4123rpm
6000rpm = good shift point
6500rpm = great shift point

3rd gear rpm = 6000 (1.308/1.902) = 4126rpm
6000rpm = great shift point, puts you right in the power band.

So, it is obvious, you would want to shift later for the stock 280Z 5spd @6500rpm to get 4000rpm at the shift. The NISMO on the other hand works better when shifted 6500 from 1st to 2nd, and 6000 from 2nd to 3rd. This helps save your engine, while keeping it in the power band, very nice!

> What's the ceiling compresion ratio that can
> be run safley on one of the 2.8's. My 3.1
> sits at 10.6:1. Can the 2.8's do the same?
> What was stock from Nissan?

You're at about the limit with pump gas. I would keep an ear on things for the first signs of pinging. Stock L28 varied, but I think the flat top piston versions (280ZX) had about 8.8:1. I try to run 10:0 and below on street cars. Keep in mind, that we are just talking about static compression. It's just a ratio of the volume of air that is compressed. If you include the cam specs, now you're talking dynamic compression. This takes into account the air velocity which affects overall air density in the combustion chamber which affects the ultimate compression. This is always higher than static, because of the air velocity taken into account. But, this is getting into thermodynamics, and there isn't enough time or space to go into that here. I just use 10:1 staic as my safety margin based on experience. And yes, compression ratio is the same for all the L series engines as far as what you may or may not run. It only depends on what you want and how you get it.

> Sorry for all of the questions, but I'm
> finding more and more diffrences between 3.1
> vs 2.8 and Fuel injection vs Carbed as we
> go.

That is why it made such a huge difference when you said you have a 3.1L instead of 2.8L. These cars are so interchangeable, there are many ways to do the same thing. The main reason carbs work better for high rpm, is like I stated before, they allow alot of air and fuel into the engine with minimal restriction. Think of it like this.(This is oversimplified, because not all of the cylinders are 'breathing' at the same time.) Say the throttle body is 60mm /6 cylinders = 10mm air flow per cylinder. A triple carb with 30mm chokes is = 30mm air flow per cylinder. Thats a 66% increase over the TB. I think the ultimate setup would be individual throttle bodies with fuel injection, running a TEC II. That would give you tons of power and infinite tuneability.

I don't mind answering some questions, this is actually fun hearing what others have done and experienced.

240Dave
 

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Discussion Starter #4
Close ratios explained...sort of

Here's why they call NISMO tranny's close ratio.

Stock 280Z 5spd
1st: 3.321
2nd: 2.077
3rd: 1.308
4th: 1.000

Difference between 1st/2nd = 3.321/2.077= @1.59
Difference between 2nd/3rd = 2.077/1.308= @1.59
Difference between 3rd/4th = 1.308/1.000= @1.31
This has uneven spacing between gears, with a huge drop from 2-3 to 3-4. Not good for keeping rpms up.

Stock 280ZX 5spd
1st: 3.062
2nd: 1.858
3rd: 1.308
4th: 1.000

Difference between 1st/2nd = 3.062/1.858= @1.65
Difference between 2nd/3rd = 1.858/1.308= @1.42
Difference between 3rd/4th = 1.308/1.000= @1.31
This has more even spacing, and is why it is considered a 'closer ratio' tranny.

NISMO 32010-N3130 5spd
1st: 2.906
2nd: 1.902
3rd: 1.308
4th: 1.000

Difference between 1st/2nd = 2.906/1.902= @1.52
Difference between 2nd/3rd = 1.902/1.308= @1.45
Difference between 3rd/4th = 1.308/1.000= @1.31
This has even lower ratio spacing, and is lower to begin with. This puts the engine in the powerband sooner and keeps it there between all the shifts.

Ok, enough math for me. Hope you can get the idea of how this stuff is so related. This is why just bolting on parts isn't always a good idea. A 'matched' engine and drivetrain will work and perform way better than a powerful engine and bag gearing. This is why my e.t is so low. Even though the engine has plenty of power and pulls up to 6500, the gearing doesn't allow me to fully take advantage of all the engines power. I'd say you have a high ratio R200 in that car of yours, and is another reason why you are able to post low 13's. My belief is that it's always better to be informed about WHY you are bolting that part on there.

240Dave
 

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Tranny talk

> Nope, the 4 barrel carb setup doesn't
> distribute fuel evenly on a straight six,
> and you will run into a lean condition. They
> may work fine when sitting atop a V8, but
> don't work well for a side induction
> straight six. Don't get this, stay with your
> fuel injection. Besides the fuel injection
> is working quite well if you're running in
> the 13's.
> The only way you are going to strenghten the
> top end is to install a different cam, or
> upgrade the intake to independent runners.
> This would improve throttle response and
> provide more air for higher rpm. Maybe a
> 3 exhuast would help also. I'm looking
> into some 3 oval pipe for my center
> section, then I can run 3 pipe on a
> N/A. Talk about minimal restriction!!

> Well, lets do some math, and see what would
> happen. Using the example posted below:
> Say you're torque curve is farily flat from
> 4000-5500 @210ft/lbs and falls to 200ft/lbs
> @6000. Therefore you don't want to drop
> below 4000 rpm, because you'll be below the
> peak torque. We'll just say shift at 6000
> for both, and notice the difference.

> Stock 280Z 5spd
> 1st: 3.321
> 2nd: 2.077
> 3rd: 1.308
> 4th: 1.000

> 2nd gear rpm = 6000 (2.077/3.321) = 3752rpm
> 2nd gear rpm = 6500 (2.077/3.321) = 4065rpm
> 6000 = poor shift point
> 6500 = better shift point
> 3rd gear rpm = 6000 (1.308/2.077) = 3778rpm
> 3rd gear rpm = 6500 (1.308/2.077) = 4093rpm
> 6000 = poor shift point
> 6500 = better shift point

> NISMO Close-Ratio 5spd p/n 32010-N3130
> 1st: 2.906
> 2nd: 1.902
> 3rd: 1.308
> 4th: 1.000

> 2nd gear rpm = 6000 (1.902/2.906) = 3927rpm
> 2nd gear rpm = 6300 (1.902/2.906) = 4123rpm
> 6000rpm = good shift point
> 6500rpm = great shift point

> 3rd gear rpm = 6000 (1.308/1.902) = 4126rpm
> 6000rpm = great shift point, puts you right
> in the power band.

> So, it is obvious, you would want to shift
> later for the stock 280Z 5spd @6500rpm to
> get 4000rpm at the shift. The NISMO on the
> other hand works better when shifted 6500
> from 1st to 2nd, and 6000 from 2nd to 3rd.
> This helps save your engine, while keeping
> it in the power band, very nice!

> You're at about the limit with pump gas. I
> would keep an ear on things for the first
> signs of pinging. Stock L28 varied, but I
> think the flat top piston versions (280ZX)
> had about 8.8:1. I try to run 10:0 and below
> on street cars. Keep in mind, that we are
> just talking about static compression. It's
> just a ratio of the volume of air that is
> compressed. If you include the cam specs,
> now you're talking dynamic compression. This
> takes into account the air velocity which
> affects overall air density in the
> combustion chamber which affects the
> ultimate compression. This is always higher
> than static, because of the air velocity
> taken into account. But, this is getting
> into thermodynamics, and there isn't enough
> time or space to go into that here. I just
> use 10:1 staic as my safety margin based on
> experience. And yes, compression ratio is
> the same for all the L series engines as far
> as what you may or may not run. It only
> depends on what you want and how you get it.

> That is why it made such a huge difference
> when you said you have a 3.1L instead of
> 2.8L. These cars are so interchangeable,
> there are many ways to do the same thing.
> The main reason carbs work better for high
> rpm, is like I stated before, they allow
> alot of air and fuel into the engine with
> minimal restriction. Think of it like
> this.(This is oversimplified, because not
> all of the cylinders are 'breathing' at the
> same time.) Say the throttle body is 60mm /6
> cylinders = 10mm air flow per cylinder. A
> triple carb with 30mm chokes is = 30mm air
> flow per cylinder. Thats a 66% increase over
> the TB. I think the ultimate setup would be
> individual throttle bodies with fuel
> injection, running a TEC II. That would give
> you tons of power and infinite tuneability.

> I don't mind answering some questions, this
> is actually fun hearing what others have
> done and experienced.

> 240Dave

I talked to a man, late last night, that my mechanic got to call me, that has one of the close ratio trannys. He has a 2.8 with about 200 horse, that my mechanic built.(So I know the figures are right.)

He says that my 0-60 times(5.5) are faster than but he bet his 0-100 or even 0-120 times are faster than mine. Juddging by the numbers, I can see how it may be possible, but I would like to see it. I just think that the horspower diffrence and the torque diffrence would let my car walk on this guy.

About the compresion.
Well, a good friend of mine was running a N/A '77 Z that was sitting about 10.5:1 compresion, and he had 225 horse. Well, on a very spirited trip from Burleson, to Downtown Ft. Worth,(14 miles), and then through downtown,(4 miles), when we pulled into the parking lot, we heard a slite PING. I thought to myself, Only bad things can come from this sound. Never hearing the sound come from a N/A Z before, I surely didn't figure the ping-monster was visiting. Well, on the way home, sure enough, the ping-monster was visiting, and was here to stay. The engine was gone by the time we got home, and the head gasget blew the following week. The exhaust manifold torqued off the block,(As mine did when I blew my last engine. Common problem with the Z's.) and he had to relace his engine.

He went with a Turbo engine the next round. Took it out of an '83 Turbo car. Boy the car would scream, but it only did it for about 6 months. He ran 8.6:1 normally. Problem was, he got to where he was running 15 punds of boost, WITHOUT a heavy duty intercooler. After 3 or 4 runs late one night, the car died out on some deserted country road. So, since I was riding with him both times, I know all too well what the horrible, horrible PING sounds like. The only good thing that came out of this, is that he bought a T/A, so now he will stop destroying Z cars. His T/A is a custom '79 Twin Turbo 350, so that car may not last long either.

If I try to run anything less than 93 octane, I can't hardly get the car start. I tried it once, and I regreted it. It wouldn't hardly run, and I spent the rest of the day apologizing to my car.

Ok, time for a few more questions.

My car,(82 280ZX N/A) has a temp. gauge. No numbers on the gauge, just an F right in the center. My stock engine would always reach the F and then never pass it. So, I assumed this is where it is supposed to run. Well, my new engine, never even reaches the F. It sits about half way between the bottom point, and the F. So, I have very good reason to believe this engine is running MUCH cooler than the last one. Do you have any idea what the F represents as far as temp readings? Here's one of the few times you'll hear me ask for #'s.

With all of the work that I had done, as far as radiator(in excess of $250 for custom rad.), water pump,($120 from NISMO), and all of the high speed belts and pullies(about $300) that are on the front of this engine, I know it has a much better cooling system, and I attribute part of the efficiency of the motor to this. I just don't know an optimal temp reading for my engine compared to stock engines, as far as #'s go. All I know to tell someone when they ask is, Well, it sits about a 1/4 of the way up the gauge.

In the last motor, I ran 89 octane as compared to 93 octane now. How much of a diffrence do you think this made? I've seen it make a noticable diffrence in performance and temp in a V-8.

Do the 240Z's, 260Z's and the 280 series have about the same running temp?

Take it easy,
Chris Behney
 

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Discussion Starter #6
Temperatures

Take a look at the link below, it's a David vs. Goliath situation. It's about a 1.5L Porsche vs. 4.9L Ferrari. The whole story is alot longer, but it just proves that hp/torque are not the be all end all of everything. In dragracing, you just upshift, and mash the accelerator. With road racing, the hp/torque are not as important as consistency between gears to keep the engine in it's powerband and suspension/brakes/driver. My point is that I'm sure you'll beat the other guy with the close ratio, but you might be surprised how he keeps up.

> Ok, time for a few more questions.

> My car,(82 280ZX N/A) has a temp. gauge. No
> numbers on the gauge, just an F right in the
> center. My stock engine would always reach
> the F and then never pass it. So, I assumed
> this is where it is supposed to run. Well,
> my new engine, never even reaches the F. It
> sits about half way between the bottom
> point, and the F. So, I have very good
> reason to believe this engine is running
> MUCH cooler than the last one. Do you have
> any idea what the F represents as far as
> temp readings? Here's one of the few times
> you'll hear me ask for #'s.

The low point is 120F and high point is 250F. The middle is about 185-190F. Z's like this temperature.

> With all of the work that I had done, as far
> as radiator(in excess of $250 for custom
> rad.), water pump,($120 from NISMO), and all
> of the high speed belts and pullies(about
> $300) that are on the front of this engine,
> I know it has a much better cooling system,
> and I attribute part of the efficiency of
> the motor to this. I just don't know an
> optimal temp reading for my engine compared
> to stock engines, as far as #'s go. All I
> know to tell someone when they ask is,
> Well, it sits about a 1/4 of the way
> up the gauge.

I'm assuming you have a 4-row radiator. The main reason you are running so cool, is that you have such a good cooling system. 4-row radiators were designed to handle high heat loads, encountered during high rpm races and such. When you take the same setup and drive around town, you just aren't creating alot of heat, and the radiator ends up radiating more heat than is necessary. Based on what you say, you're probably running around 160-170F. This is a little cool, but then it's better than running too hot. Most Z engines I've seen, enjoy a some heat. They run best at 180-190F.

> In the last motor, I ran 89 octane as
> compared to 93 octane now. How much of a
> diffrence do you think this made? I've seen
> it make a noticable diffrence in performance
> and temp in a V-8.

If the engine was designed for 89, then run 89. Octane is a rating that determines a gasolines resistance to knock. A higher octane means the gas is HARDER to burn. This is why they resist hot spots that develop in higher compression engines, and why high octane is recommended for high compression. When you compress air, you heat it, and the more you compress it, the hotter it gets. This is why they have intercoolers on Turbos and such. This is why turbocharged and high compression engines require high octane. In your particular situation, the car might have needed the higher octane, due to deposits or something. Again, put in what the car was designed for. Of course, your new 3.1L is HIGH compression, so you obviously need the high octane gas. But, if you built it closer to stock, you could run 89 with no problems or loss of performance. Just run the minimum octane to eliminate knocking is a good rule of thumb. Higher octane is better insurance, but not always necessary.

> Do the 240Z's, 260Z's and the 280 series
> have about the same running temp?

Yes, they should run about the same temp. The 240Z ran a little hotter, because it had a 2 row radiator instead of the 3 row radiator in 280Z.
Just as a side note, when I originally installed the 2.8L in my 240, I still had the original 2 row radiator. This worked fine for daily driving, but when driving hard, even for short bursts, the temp would skyrocket by 15-20F! But, it worked fine around town. I've since installed a 3 row radiator from a 280Z and have noticed the temp does not rise much when I drive hard now. Of course, the 4 row would almost eliminate this problem. I'm not planning on a 4 row, but am going to install a oil cooler. I feel it's more important to keep the oil cool, than to over cool the coolant.

240Dave
 

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195 Posts
I agree

> Take a look at the link below, it's a David
> vs. Goliath situation. It's about a 1.5L
> Porsche vs. 4.9L Ferrari. The whole story is
> alot longer, but it just proves that
> hp/torque are not the be all end all of
> everything. In dragracing, you just upshift,
> and mash the accelerator. With road racing,
> the hp/torque are not as important as
> consistency between gears to keep the engine
> in it's powerband and
> suspension/brakes/driver. My point is that
> I'm sure you'll beat the other guy with the
> close ratio, but you might be surprised how
> he keeps up.

> The low point is 120F and high point is
> 250F. The middle is about 185-190F. Z's like
> this temperature.

> I'm assuming you have a 4-row radiator. The
> main reason you are running so cool, is that
> you have such a good cooling system. 4-row
> radiators were designed to handle high heat
> loads, encountered during high rpm races and
> such. When you take the same setup and drive
> around town, you just aren't creating alot
> of heat, and the radiator ends up radiating
> more heat than is necessary. Based on what
> you say, you're probably running around
> 160-170F. This is a little cool, but then
> it's better than running too hot. Most Z
> engines I've seen, enjoy a some heat. They
> run best at 180-190F.

> If the engine was designed for 89, then run
> 89. Octane is a rating that determines a
> gasolines resistance to knock. A higher
> octane means the gas is HARDER to burn. This
> is why they resist hot spots that develop in
> higher compression engines, and why high
> octane is recommended for high compression.
> When you compress air, you heat it, and the
> more you compress it, the hotter it gets.
> This is why they have intercoolers on Turbos
> and such. This is why turbocharged and high
> compression engines require high octane. In
> your particular situation, the car might
> have needed the higher octane, due to
> deposits or something. Again, put in what
> the car was designed for. Of course, your
> new 3.1L is HIGH compression, so you
> obviously need the high octane gas. But, if
> you built it closer to stock, you could run
> 89 with no problems or loss of performance.
> Just run the minimum octane to eliminate
> knocking is a good rule of thumb. Higher
> octane is better insurance, but not always
> necessary.

> Yes, they should run about the same temp.
> The 240Z ran a little hotter, because it had
> a 2 row radiator instead of the 3 row
> radiator in 280Z.
> Just as a side note, when I originally
> installed the 2.8L in my 240, I still had
> the original 2 row radiator. This worked
> fine for daily driving, but when driving
> hard, even for short bursts, the temp would
> skyrocket by 15-20F! But, it worked fine
> around town. I've since installed a 3 row
> radiator from a 280Z and have noticed the
> temp does not rise much when I drive hard
> now. Of course, the 4 row would almost
> eliminate this problem. I'm not planning on
> a 4 row, but am going to install a oil
> cooler. I feel it's more important to keep
> the oil cool, than to over cool the coolant.

> 240Dave

I agree completly, that HP is not the ned all be all. If I had to road race this car, I would be eaten alive. Ever turn I went around, the tires would break loose, followed by a tire burning doghnut! This car hates curves. It's stiff, and handles the curve itself, just fine, very little body roll. But, I can't keep traction. Any stock 280ZX in town, will eat my lunch on a curve. But, when it comes to hard launches, at 4000rpm! OH BABY, your in my nieghborhood now!

The guy with the close ratio tranny is going to stop by the meeting next week, or get a hold of me this weekend, so I can drive his car.

I'll let ya know how it turns out.

Chris Bhehney
 
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