[Matthew Tucker]

Re: catyl. conv. breaths better now

> I think youd be better off with the headers
> from motorsport they are cheaper and in my
> opionon alot better performance wise

I haven't done the headers yet, but.... I had my exhaust down when I changed my tranny. When I pulled the cat off about a half a cup of crud dumped out of the intake side. Twenty years of.....stuff. I said to myself, Now that's something, this couldn't have been breathing too well. Somehow within a few minutes a rather large hole appeared straight through the honeycomb. Huge difference in top end performance.

SO, The moral of the story is, if you're doing the exhaust, don't leave your cat bolted up without inspecting it, and maybe helping it perform a little easier.

Good Luck,

Matt

PS Let us know which headers you go with and how they perform.

 

[Matthew Tucker]

Re: catyl. affects Emissions?

> So if my catyl conv develops a
> hole, how will that affect my emissions?
> Anyone know? I would assume some levels
> would go up, but which? My state (Georgia)
> does require an emissions inspection so I'd
> hate to have a hole develop and mess up my
> inspection,

> kordon

Kordon, I haven't checked since the removal. And I probably won't since I have been registering my vehicle in another rural county that doesn't require any emissions.

However, When I did test my car in the past, based on the year of the car('78), the requirements in my state were so low that it wasnt' even close to not passing. The fuel injection really helps in eliminating unburned emissions. I would suppose that your car would have to be running pretty poorly to not pass after cleaning out the cat. If you're really concerned, you could always pick up a used cat at the yard, modify its flow charicteristics, and if your emissions suffer just bolt the original back in. 10 minutes of work.

 

[Matthew Tucker]

Re: environment and ? (long)

> Removing the cat may or may not affect your
> tailpipe test. This depends on the condition
> of your engine, and the levels of pollution
> allowed in your area. If your engine is very
> efficient, the levels of NOx may be low
> enough to pass without the CAT installed,
> but if your engine was running poorly and
> had the CAT installed, it would still pass.
> So, it can be a gamble, depending on how
> confident you are with the tune of your
> engine.

> Case and point: My engine is a 2.8L with
> triple webers and while tuning it, it was
> hooked up to a exhaust analyzer. It turned
> out that my 2.8L put out only 200ppm more
> NOx than a typical 280Z with fuel injection
> and CAT installed. The reason for this is
> that my engine is more efficient. However,
> if I was to install a CAT, my emissions
> would be much lower than that of the stock
> 280Z, since I'm already more efficient to
> begin with. Personally, I'd keep a CAT if I
> had one. I'd just get a free-flow design.
> Many companies make such CATs, and they
> don't rob horsepower like they used to. The
> stock Datsun CATs are quite old (15+years)
> and were of an older design. I wouldn't be
> surprised if they were robbing significant
> amounts of hp, due to them falling apart,
> and becoming a restriction. Just replace it
> with a new one. I used to have a HONDA, and
> always ran the CAT. There was only a SLIGHT
> increase in hp with it removed. Actually,
> the engine liked the backpressure that it
> provided. It had a better torque curve with
> the CAT installed. So I voted to keep the
> CAT installed, and have cleaner running
> engine (and air), for the sake of a few hp.

> The CAT is used to convert NOx (Nitrogen
> oxides) back into Nitrogen and Oxygen using
> a catalyst (hence the name catalytic
> converter). NO engine is 100% efficient.
> Fuel injection, powerful sparks, re-designed
> combustion chambers, etc... all help to make
> the engine more efficient. But, man has yet
> to make a 100% efficient internal combustion
> engine. You can get emissions extremely low
> (Honda has a ULEV Accord), but they still
> exist, and will not go away completely.

> Alternative fuels (propane, hydrogen) do not
> need a CAT. This is because they are of a
> different molecular compound than gasoline,
> and the product of their combustion is not
> the same.

> Of course less emissions are better than
> more. This is why a CAT is used. It cleans
> up the unburned gases and reduces them back
> to their original elements. Otherwise these
> 'radicals' can begin reacting with other
> elements and create smog, which causes lung
> problems, which causes acid rain, which eats
> away at buildings, paint etc....

> Guess my California upbringing is evident
> now.

> Just my .02
> 240Dave

Thanks for the post Dave. Yea we should take better care of the earth, but that's what the masses are doing with their new cars, right, ???
Besides, after flying into Mexico City, Seoul, Bangkok, etc. several times, I realized nothing we do here in the States can make up for all the crap they're spewing into the air there. But, we can keep our back yards clean, right?

After reading your post I was curious as to my readings before removal, so I found the last test. It was from 2-98. I don't know what all these things are, but they look pretty low to me. I'm very curious as to what others' Zs are testing after 20 years. And you compared your 200 ppm more than a typical Z, is mine typical. Any feedback would be interesting, though probably not very important. Mine is a 1978, stock engine with 134,000.

high speed results: reading limit

HC ppm 4 500
CO% .01 3.0
CO2% 13.1
O2% 19.9
RPM 2411

idle results

HC ppm 58 500
CO% 0.0 3.0
CO2% 12.7
O2% 19.8
RPM 804

Tests in previous years always yeilded the same results. I'm real curious what it's doing now, because I've not only removed the cat, but also adjusted the AFM and advanced the timing.

I think even though I don't have to have it done for licensing. I might still have them run it through to check what it's doing. Maybe if I catch them on a slow day, they might even let me take my screw driver out for a few minutes.

Question. Which of these readings tells me how rich or lean it's running?

Thanks,

Matt

 

[Matthew Tucker]

Re: tests are accurate (longer)

> Yeah, it's kind of hard to keep the air
> clean, when crap from China just floats on
> over in the jetstream, but hey, we've got to
> start somewhere. I actually read an article
> about the Honda ULEV engine. They said that
> if you drove that car around L.A., you would
> actually be CLEANING the air!! The Honda
> puts out less pollution than what's already
> in the air.

> Mine is a 1978, stock engine

> Wow, 4 ppm is quite low. Are you sure they
> tested it right?? That is one of the
> cleanest readings I have ever seen. Most
> I've seen run about 150-250 HC ppm. My car
> was about HC 400ppm. I don't have a
> printout, but next time I go to the dyno, I
> may have one done. I guess Nissan knew what
> they were doing way back in 1977 to get a
> car to run that clean.

> These are also extrememly low. Sure you
> didn't pay the guy taking the test?? I
> would say that if you removed your CAT, you
> would still be well within limits, if your
> car runs this well. Of course all the HC and
> CO would go up, but still passable I would
> imagine.

> The value that indicates rich/lean, would be
> the CO and HC. The higher these values, the
> richer your engine is running. The HC is
> UNBURNED fuel, which obviously means there
> is too much fuel, or a rich condition. Your
> car is running very lean. Does your car run
> hot?? Leaner conditions make cars run
> hotter. A basic rule is to run rich rather
> than lean. As there are more consequences to
> running lean than there are running rich.

Yeah, it's right. I've had the same readings since I first licensed it in '91. It went into storage for a few years and then back on the road in '97. It's good to know, because now I have a solid baseline to compare to in the future.

Every time I tested it the technician (well, the drop-out working at the 10 Minute Emissions) would shake his head and say he'd never seen an old car with that low of a reading. I guess Nissan did know what they were doing. And, for my sake, I guess the previous owners really took nice care of it. Lucky me.

That's a very intersesting comment about running lean is worse than running rich. About a week ago there was quite the response to this very question, after Phantom exclaimed his engine was trashed after running too rich. He stated that his cam and rings are scored because of this condition. It never really made too much sense to me, but I was curious because of the adjustments I had recently made to my clean burning engine. I had adjusted the AFM spring and richened up the idle mixture screw on the AFM. I got a little bit of a cold running problem-- probably running too rich. So I tightened the AFM spring a notch or two and the problem went away.

I know I was still running too rich at idle because I could smell it. so I leaned it back out. I don't really know where I am now unless I take it in and have them stick a probe in the pipe. Is there another way to know how rich or lean it's running? How did they do it before the analyzers?

What I do know is, after reaming out the cat, advancing the timing, changing to synthetic, putting in new NGK four prongs, loosening the AFM spring, adjusting the valves, running three or four tanks of techron cleaner, and washing the car---- it runs like a bat out of ****. Well, I want more, but now it's reving like it never has since I've owned it.

Any ideas on what I should do next?

Cam (reccomendations)?

Exhaust?

Headers?

K&N?

Is there really a good bang for the buck? I suspect it's like what I did; they all help a little and add up when done together.

How does your car run? Approximate 0-60s or HP. What else have you done besides the triples?

I think, based on lame stopwatch calcs, I'm running high eights to low nines. That's at 5,000 to 6,000 feet in Utah and shifting at about 6,000 rpms. It seems like it starts to flatten there, so I shift. I'd love to see low sevens or sixes. What do you think it would take? Oh, one more thing. I've put in a late 5 speed with the closer synchro 1,2 gears, but taller. Would it really make that much difference to go to a 3.9:1 rear-end? Unfortuneatly, for comparrison, when I changed the tranny I cleaned the CAT, so It actually improved my accelleration.

Thanks for your feedback. It's nice to get some intelligent responses.

Later,

Matt

 

[Matthew Tucker]

Re: S

> The reason I feel running rich is better
> than running too lean is for two reasons.

> 1) You don't lose as much hp, by running
> rich. The leaner you go, the more rapidly hp
> begins to drop off.

> 2) Lean conditions cause pinging, and hot
> running engines. Unless the engine is
> designed to handle that effectively, you can
> cause serious damamge. As opposed to just
> having carbon buildup from a rich running
> engine and occasional backfiring. I'd rather
> have the carbon than the pinging. Wouldn't
> you??? Of course the magic 14.7:1 ratio is
> the best. It's a stoichiometric ratio
> (meaning it's the ratio of fuel:air at which
> 100% combustion is possible).

> Well, now you're getting into a whole
> different bag of tricks. There are many ways
> to go with this, depending on what you want.

> Unless you are porting the head for higher
> flow, a high lift cam (.500+) isn't
> going to do anything for you. One thing you
> can do, is to install a longer duration cam.
> You can actually have your current cam
> reground to make it longer duration. I think
> 265-280 duration works great. The longer
> duration will allow you to rev STRONGLY up
> to 6500. Although the 280 duration can be a
> little lopey. If you get the 265-270
> duration, you might actually help the engine
> stay clean, as Z cams are notorious for
> being undercammed. Although they are very
> easy to overcam as well.

> Here's another area where it's easy to gain
> a few hp. 2 1/2 is a very popular
> setup, although 2 1/4 can work quite
> well. The 2 1/2 is a little louder,
> and can rob some low rpm torque. The 2
> 1/4 works best for all around daily
> performance. Just have a shop make one up
> for you with a high quality muffler. e.g.
> Dynomax Ultraflo, Borla, etc....Careful,
> these can get LOUD!!

> I wouldn't bother unless I had the exhaust
> & cam already. Since you need to smog
> your car, the Nissan Motorsports are out of
> the question. You might pass the tail-pipe
> test, but you'll fail the visual inspection.
> I think the Motorsports Auto 3-2 setup is
> crap. The 6-1 design is alot better,
> although it can't compare to the Nismo.

> Highly recommend it. I ran K&N on all my
> other cars, and what a difference. Besides,
> you can just clean it when it's dirty, and
> re-install it. I like the idea of not having
> to buy a new filter every 6 mo., and
> actually get a few hp to boot.

> You're absolutely right. You have to think
> of the engine as a system, and need to
> consider all aspects of it when making a
> change. This is why I would recommend
> getting a cam after the exhaust and K&N.
> Otherwise, it won't be able to do it's job,
> and pull in more air, because you've still
> got restrictions. The key to modifying an
> engine is BALANCE. You want the amount of
> air in to = the amount of air out. Any
> difference will change the characteristics
> of your engine.

> I've done alot to my current engine, and am
> doing more as we speak. It's a long list of
> mods. Basically, I'm running 9.6:1
> compression, fully ported polished head.
> Port matched intake manifold. Nismo headers
> with 2.5 exhaust(soon to be 3).

> Right now, my engine puts out about 220hp
> (gross). I based this on information
> gathered from some reputable engine builders
> in the area. With my new cam, and 3
> exhaust I should be approaching
> 250hp(gross). I'm still running the stock
> 240 cam, so I'm missing out on ALOT of top
> end. My engine runs out of steam @6000rpm.
> I'm going to dyno it this summer.

> So far, I've run [email protected] I think that works
> out to about mid 6 second 0-60 range. This
> is with a 280Z 5spd and stock R180 3.364:1
> diff. I'm planning on upgrading to a 3.7 or
> 3.9 R200 this summer. Should improve my
> times to mid 14's and low 6 second 0-60.

> Sure will. Might be shifting a little more,
> but it'll help you get going.

> Dave

 

[Matthew Tucker]

Re: Thanks for the Info! more

> The reason I feel running rich is better
> than running too lean is for two reasons.

> 1) You don't lose as much hp, by running
> rich. The leaner you go, the more rapidly hp
> begins to drop off.

> 2) Lean conditions cause pinging, and hot
> running engines. Unless the engine is
> designed to handle that effectively, you can
> cause serious damamge. As opposed to just
> having carbon buildup from a rich running
> engine and occasional backfiring. I'd rather
> have the carbon than the pinging. Wouldn't
> you??? Of course the magic 14.7:1 ratio is
> the best. It's a stoichiometric ratio
> (meaning it's the ratio of fuel:air at which
> 100% combustion is possible).

> Well, now you're getting into a whole
> different bag of tricks. There are many ways
> to go with this, depending on what you want.

> Unless you are porting the head for higher
> flow, a high lift cam (.500+) isn't
> going to do anything for you. One thing you
> can do, is to install a longer duration cam.
> You can actually have your current cam
> reground to make it longer duration. I think
> 265-280 duration works great. The longer
> duration will allow you to rev STRONGLY up
> to 6500. Although the 280 duration can be a
> little lopey. If you get the 265-270
> duration, you might actually help the engine
> stay clean, as Z cams are notorious for
> being undercammed. Although they are very
> easy to overcam as well.

> Here's another area where it's easy to gain
> a few hp. 2 1/2 is a very popular
> setup, although 2 1/4 can work quite
> well. The 2 1/2 is a little louder,
> and can rob some low rpm torque. The 2
> 1/4 works best for all around daily
> performance. Just have a shop make one up
> for you with a high quality muffler. e.g.
> Dynomax Ultraflo, Borla, etc....Careful,
> these can get LOUD!!

> I wouldn't bother unless I had the exhaust
> & cam already. Since you need to smog
> your car, the Nissan Motorsports are out of
> the question. You might pass the tail-pipe
> test, but you'll fail the visual inspection.
> I think the Motorsports Auto 3-2 setup is
> crap. The 6-1 design is alot better,
> although it can't compare to the Nismo.

> Highly recommend it. I ran K&N on all my
> other cars, and what a difference. Besides,
> you can just clean it when it's dirty, and
> re-install it. I like the idea of not having
> to buy a new filter every 6 mo., and
> actually get a few hp to boot.

> You're absolutely right. You have to think
> of the engine as a system, and need to
> consider all aspects of it when making a
> change. This is why I would recommend
> getting a cam after the exhaust and K&N.
> Otherwise, it won't be able to do it's job,
> and pull in more air, because you've still
> got restrictions. The key to modifying an
> engine is BALANCE. You want the amount of
> air in to = the amount of air out. Any
> difference will change the characteristics
> of your engine.

> I've done alot to my current engine, and am
> doing more as we speak. It's a long list of
> mods. Basically, I'm running 9.6:1
> compression, fully ported polished head.
> Port matched intake manifold. Nismo headers
> with 2.5 exhaust(soon to be 3).

> Right now, my engine puts out about 220hp
> (gross). I based this on information
> gathered from some reputable engine builders
> in the area. With my new cam, and 3
> exhaust I should be approaching
> 250hp(gross). I'm still running the stock
> 240 cam, so I'm missing out on ALOT of top
> end. My engine runs out of steam @6000rpm.
> I'm going to dyno it this summer.

> So far, I've run [email protected] I think that works
> out to about mid 6 second 0-60 range. This
> is with a 280Z 5spd and stock R180 3.364:1
> diff. I'm planning on upgrading to a 3.7 or
> 3.9 R200 this summer. Should improve my
> times to mid 14's and low 6 second 0-60.

> Sure will. Might be shifting a little more,
> but it'll help you get going.

> Dave

Some thing happened when I was writing ans the silly system launched my post before I was done.

Anyway thanks for the info. I am very interested in the NISMO headers. I don't have to smog the car because I register it at another residence in a rural county-- no smog test, just safety.

How much do the NISMOs run and shouldn't I do them when I do the exhaust? Also, how do you get a muffer shop to shoot a pipe straight out the back, when the car (78) calls for a CAT. Isn't that illegal for them to do? Or do you just find a specialty shop that doesn't ask questions?

On the cam, I've heard you can decrease the valve lash spec, and get a similar result to longer duration. Any knowledge on this and how much you can go before you've gone to far and lost your ramp?

Thanks,

Matt

 

[Matthew Tucker]

Re: Nismo & other suggestions...

> $300.00 and if you do them with the exhaust
> that would be great. It's easier to do
> everything at once. But, don't expect to get
> the most hp out of the headers until you
> install the cam and modify the intake and
> other items. A degreed cam gear might be a
> good idea as well.

> You can order a catalog from:
> Nissan Motorsports
> P.O. Box 191
> Gardena, CA 90248-0191
> (310) 538-2610 voice
> (310) 538-1462 fax

> Also, how do

> Have them fab a pipe from the header to the
> CAT, then from CAT back. Then when you get
> home, you can either keep the CAT, make a
> hole appear in it with a broomstick, or buy
> a high flow version. Depends on what your
> conscience tells you to do. Yes, it is
> illegal for them to remove smog equipment,
> and if you find someone who'll do it, you're
> lucky. They can get HUGE fines for such
> things.

> Yes, that does affect the overall duration.
> It is effectively keeping the pad in contact
> with the cam lobe for a longer time, thus
> keeping the valve open longer. Don't expect
> more than a few degrees from this mod
> though. And, you have to be careful as to
> how tight the valves are, because you don't
> want them to get too hot. They need to fully
> seat in the head when closed to transfer the
> heat into the head. If the clearance is too
> small, they will not fully seat when
> everything is up to temp, and may burn on
> you. The smallest clearance I'd run on the
> Intake would be .005 and .006
> exhaust.

Great info.

I think I'll try the valve lash mod and see if I feel any difference.

On the K & N, is there any difference in performance between the ram air set-up and just replacing the stock filter? $125 seems like a chunk of change for a pipe. I guess if that includes the filter we're more in the $75 range. I've already removed the serpentine snorkel.

Also, I can't seem to get rid of a ticking in my valves. I'm wondering if it could be a small exhaust leak, instead of valve train noise. If the valves are adjusted, what else in the valve train could be ticking? Any ideas?

Later,

Matt