X-180 CAMS, MOP, SLA & related issues - LotusTalk - The Lotus Cars Community
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post #1 of 38 (permalink) Old 08-26-2017, 08:12 AM Thread Starter
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Smile X-180 CAMS, MOP, SLA & related issues.

A912E0107F cam, for short called '107 cam' is a standard issue on our 4 cyl Esprits. Same profile on the intake and exhaust. As in other DOHC engines, cam timing and SLA is set-up by changing the relation of the centerlines, (replacement and matching of cam pulleys.)

The 107 is an outstanding mid-range performance camshaft which came stock on the later Lotus powered Esprit.

The 104 is rare, performance profile, originally used in Lotus powered rally cars. It is one bad-ass high RPM camshaft that's completely at home on a high compression 2 liter or 2.2 liter Lotus engines.

For a The Hot Ticket- one may use 107 exhaust + 104 intake combo for the best of both worlds in a high compression or turbo Esprit for a fast street car.

107 cam, A912E0107F, 252 deg duration, 0.378" lift
- used on a stock 2 liter or a 2.2 liter with great results. Will pull up to 7,000 rpm, but will loose its edge over 5,500 rpm. Good idle and around-town driveability. You can use the stock drive train, special springs are not required, but as always, check for binding.

104 cam, A912E0104Z, 272 deg duration, 0.410" lift, - used on a high compression 2 liter or a 2.2 liter Excel for performance edge. Strong power curve all the way to 8,000 rpm, but also enough torque for lower RPM-s. Good idle and around-town driveability. Requires smaller diameter/stiffer springs and steel cam followers with longer skirt length as recommended on high RPM motors.

Some of you went this way, thus I'm wondering if anyone could quantify this upgrade.

Ideally, the stock 910 T engine, if retrofitted with 104 int cam, should be dyno-ed to find the HP&TQ increases.

Your thoughts?

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post #2 of 38 (permalink) Old 08-26-2017, 03:19 PM
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Of course, be aware that you are messing with an emissons sensitive setting. Depending upon local emissions requirements and inspection procedures, the engine may not pass inspection after the change. Be prepared to make timing the cams an annual event at inspection time. In that case, the expense of adjustable cam pulleys may be warranted.
Be aware that as in many counties in California, a visual inspection will not allow adjustable pulleys.
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post #3 of 38 (permalink) Old 08-26-2017, 04:22 PM
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Look at "Dermot's Lotus Esprit engine modification section" under cam timing, then look to Tim Engel's Excel work sheet for tables.
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post #4 of 38 (permalink) Old 08-26-2017, 08:03 PM Thread Starter
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I have looked at all data you suggested. Excellent information, it has been emulated by many Esprit owners before.
Thank you for the remainder.
Perhaps, it is a pure academic discussion, but an application of 104/107 cam combo results were never mentioned.
http://users.ox.ac.uk/~ohare/engine.htm

I'm still curious if anyone dyno-ed 104/107 combo and what were the gains.

In most States inspections are not as stringent as in CA. Some States have no inspection at all.
P.S. Perhaps it's time to move out or register car in Nevada! LOL.

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post #5 of 38 (permalink) Old 09-02-2017, 02:53 PM Thread Starter
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FYI: Lobe spacing (phasing cams), VVT

LSA /LCA spacing (ACCORDING TO David Vizard)

LCA=107° or 108° is the best for Esprit ‘107’ cams with 35.5mm inlet valves. The same engine, but w/36.8mm inlets needs LCA=111°

Comparing to any two-valver, four valve heads exhibit a huge low-lift flow.
Rule ONE
*The greater the low-lift flow is in the relation of the displacement of the cylinder being fed, the wider LCA needs to be.
*If you bore and stroke your engine, the LCA has to be tighter.
*Increasing the CR requires the optimal LCA to spread, and decreasing CR tightens it. For every CR above 10.5 add 0.75° to LCA
*The faster the intake valve is accelerated off its seat (high lift lobes), the wider the LCA needs to be.

Dyno testing reveals two factors are evident:
1. There is a narrow range of LCAs over which the engine delivers its best.
2. It is better to err on the tight side rather than the wide side. Lower LCA [-1° or -2° from optimal] delivers better torque at the lower rpm, but TOO TIGHT an LCA produces overall negative characteristics, like choppy idle and diminished low speed output. Just how much of a low-speed manners have been lost ultimately depends on the overlap used.

~~~~
Turbo engines don't like big overlap values. It is difficult to build boost while the back door is open (I.E. overlap, when both valves remain open).
Before the boost onset, the engine acts as N/A and large overlap is beneficial for scavenging.
When the turbo comes in, the large overlap hurts your performance.

Ideally, it would take two LSA settings to cover the whole rpm range. On DHOC engines, one can achieve it by phasing the intake cam.
VVT technology was developed for this purpose.


~~~~~~~Simple cam tuning rules for BOOSTED engines:
Advance intake and exhaust => more low-RPM power, less high-RPM power
Retard intake and exhaust => more high-RPM power, less low-RPM power
Less overlap => lower EGTs, faster turbo spool, less fuel consumption
More overlap => higher EGTs, slower turbo spool, more fuel consumption


*The more retarded in relation to the crank the whole event, the more top end,
*the more advanced = the more bottom and mid range power
So actually you'd end up better off taking the cams in unison either 2* each "towards each other" or "away from each other" (depending on what you want to do with the overlap) and depending on if you're widening to allow a more aggressive tune and if you want more top or mid-range with fast spool...
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post #6 of 38 (permalink) Old 09-02-2017, 04:12 PM
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List of states that require emissions testing:

Arizona: Certain Areas (Phoenix and Tucson)
California: All Areas
Colorado: Some Areas (Denver and Boulder)
Connecticut: All Areas
Delaware: All Areas
Georgia: Certain Areas (all 13 Atlanta Metro Counties)
Idaho: Certain Areas (City of Boise and Ada County)
Illinois: Certain Areas (Chicago and East St. Louis)
Indiana: Certain Areas (Gary Metro Area)
Maine: Certain Areas (Cumberland County, and the Portland Metro Area)
Maryland: Certain Areas (all DC Metro and the City of Baltimore)
Massachusetts: All Areas
Missouri: Certain Areas (Jefferson County and Franklin County)
Nevada: Certain Areas (Cities of Reno and Las Vegas)
New Hampshire: All Areas
New Jersey: All Areas
New Mexico: Certain Areas (Albuquerque Metro Area)
New York: All Areas
North Carolina: Certain Areas (48 Counties ? See the NC DMV site for more info).
Ohio: Certain Areas (Cities of Akron and Cleveland)
Oregon: Certain Areas (Cities of Medford and Portland)
Pennsylvania: Certain Areas (Cities of Pittsburgh and Philadelphia)
Tennessee: Certain Areas (Cities of Nashville and Memphis)
Texas: Certain Areas (Cities of Austin, Houston, Dallas/Fort Worth and El Paso)
Utah: Certain Areas (Cities of Ogden, Provo and Salt Lake)
Vermont: All Areas (1996 or Newer Vehicles Only)
Virginia: certain Areas (all DC Metro and Arlington)
Washington: Certain Areas (Cities of Seattle, Spokane, Tacoma and Vancouver)
Washington DC: All Areas
Wisconsin: Certain Areas (all of SE Wisconsin and the City of Milwaukee)

And growing.
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post #7 of 38 (permalink) Old 09-02-2017, 04:22 PM
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UPDATE: Since 2016, NJ does not require any emissions testing (or safety testing, for that matter) on passenger cars that are not OBDII compliant. So, there is no inspection on any four cylinder Esprits.

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post #8 of 38 (permalink) Old 09-03-2017, 05:56 AM Thread Starter
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Only 30 states require testing, and not in all areas.
https://en.wikipedia.org/wiki/Vehicl..._United_States

If anyone is interested in emissions testing topic, I suggest creating a new thread in the legal section.

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post #9 of 38 (permalink) Old 09-03-2017, 11:03 AM
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IMHO it is important to make aware, as did Tim Engel's paragraph that I quoted earlier, that doing internal mods that are not easily reversed and affect the resale and emission compliance in the majority of the country does apply to this post (and frankly many other modification posts).
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post #10 of 38 (permalink) Old 09-03-2017, 02:24 PM
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Quote:
Originally Posted by Loren View Post
IMHO it is important to make aware, as did Tim Engel's paragraph that I quoted earlier, that doing internal mods that are not easily reversed and affect the resale and emission compliance in the majority of the country does apply to this post (and frankly many other modification posts).
The EPA regulations are nothing more than a bunch of lobbyist's wrangling horse sh...it! How is converting one type of pollutant in to sulfuric acid (acid rain) better for the environment and us?
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post #11 of 38 (permalink) Old 09-03-2017, 03:10 PM Thread Starter
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Originally Posted by Loren View Post
IMHO it is important to make aware, as did Tim Engel's paragraph that I quoted earlier, that doing internal mods that are not easily reversed and affect the resale and emission compliance in the majority of the country does apply to this post (and frankly many other modification posts).
Yep, living in California has its drawbacks.
.

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post #12 of 38 (permalink) Old 09-04-2017, 01:22 PM
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Quote:
Originally Posted by Loren View Post
List of states that require emissions testing:

Illinois: Certain Areas (Chicago and East St. Louis)
Pre-OBD-II (i.e. pre-1996, therefore all 4-cylinder Esprit) cars are no longer tested anywhere in Illinois, assuming they passed their last test back in 2007.
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post #13 of 38 (permalink) Old 09-04-2017, 10:24 PM
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Fair number of states (and counties w/in states) waive the emission testing on cars older than 25 years old. This now includes much of the Esprit production at this point.

Where not waived, if you can pass the sniff testing you don't have to worry about the visual test with a cam change obviously....so that's pretty workable.

Affect the resale? So your $20K Esprit will be worth $500 bucks less? Seems like small change. Just my $.02.
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post #14 of 38 (permalink) Old 09-05-2017, 04:50 AM
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Acid rain! How did you made that up?
Frankly; I am quit happy that someone actually implemented, and reinforce, emmission control.
Have you ever been in a major city in a third world contry without emmission control? Can you imagine?
Remember years way back, a very hot summer in Pittsburgh! No way I will trade for that.
I can still make plenty of power regardless of emmission control. As long as I know what I am dealing with.

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post #15 of 38 (permalink) Old 09-05-2017, 11:32 AM
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As a former resident of Los Angeles I can speak first hand to the benefits of smog controls. It's truly a case of seeing being believing - they do work and in some parts of the world (mostly major cities) they're necessary. Those here old enough will remember the 60's and 70's when it wasn't uncommon to be stuck behind a poorly maintained car that gassed you while you waited for the light to change or traffic to clear. I don't miss that at all! While members of this forum and ones like it don't create much pollution (either do to limited use or well executed mods) we all at least tend to maintain our cars - which most regular cars owners would not do unless forced to. Add to that the fact that there are way more cars on the road now than 20-30 years ago and it's obvious that we have no choice but to endure some pollution controls on cars. I don't particularly like having to deal with CA's smog rules but I do like to breath clean air.

Now back to your regularly scheduled program......

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post #16 of 38 (permalink) Old 09-05-2017, 11:46 AM
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Colorado had a 25 year rule, no emissions after the car was 25... the year before my 89Esprit turned 25, they changed the rule to all cars made after 1975 had to have emissions tested every 2 years...!

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post #17 of 38 (permalink) Old 09-05-2017, 06:58 PM
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Incidentally to all offended by the notion of "smog testing", the vast majority of automobiles are now so compliant with emissions testing, that our collective air quality in the US is better than it has been in decades past. The small number of vehicles that meet emissions ommission(see what I did there?) is shrinking, and typically are not daily driven commuter vehicles. So their combined emission footprint is nearly negligible in comparison to the rest of the vehicles on the road. If you want to keep your Esprit Emissions compliant, by all means, do so. The point of the original post was support for modification to the camshaft profile and its overall impact on performance enhancement and power improvement.
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post #18 of 38 (permalink) Old 09-06-2017, 05:33 AM
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Originally Posted by 2Many Cars View Post
we all at least tend to maintain our cars - which most regular cars owners would not do unless forced to.
That was something that stuck in my memory from a couple trips to LA a few years ago: While CA emissions regulations and testing always seemed Draconian, there were frequently an abundance of old beaters driving around that would be running with misfiring engines...I always wondered 'What's up with that?"

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post #19 of 38 (permalink) Old 09-06-2017, 12:18 PM
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The topic:
X180 Cams,MOP,SLA & related issues
Now if making modifications internally that effects the passing of emission standards in many states isn't a related issue, I'm sorry.
Tim Engel's disclaimer is totally correct and needs to be acknowledged.
When I stated resale, I wasn't talking resale value, although that plays a big part in the equation, I was commenting on the resale from a non compliant state to a state that requires compliance in order to licence and register a vehicle.
Imagine buying a vehicle from an out of state previous owner that decided camming was a good idea only to find out you can't register the car in your state.
I haven't looked up the full history of my car but its recent registrations are Washington State, New York State and to me in California.
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post #20 of 38 (permalink) Old 09-07-2017, 08:57 AM Thread Starter
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This is just a discussion...

I thought, this forum has "Talk" in the title?

In addition, all members here are well past the drinking age and pretty smart not to do any dumb things.

Last edited by MRDANGERUS; 09-21-2017 at 06:27 AM.
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