X180 IMPROVEMENTS - Page 5 - LotusTalk - The Lotus Cars Community
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post #81 of 493 (permalink) Old 12-10-2014, 09:46 AM
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The stock turbo exhaust valve stem diameter is 7.955 - 7.970 mm.
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post #82 of 493 (permalink) Old 12-10-2014, 02:14 PM
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thanks for the nice thread. Will probably implement the rubber boot heat shield ASAP
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post #83 of 493 (permalink) Old 12-14-2014, 06:12 AM Thread Starter
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post #84 of 493 (permalink) Old 12-24-2014, 06:59 AM Thread Starter
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FYI: In general, to maximize the flow of the head for turbo application, the exhaust valve should be ~90% of the intake.
The "early" (85-93) Lotus head (carry-over from N/A !) is at 86% (30.7mm Exh).
Installation of the 32mm exh valve, brings this ratio to 90.14%.

Last edited by MRDANGERUS; 12-24-2014 at 10:09 AM.
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post #85 of 493 (permalink) Old 12-24-2014, 07:39 AM
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Thats sort of true in general terms but you have to explain the details of the considerations and what needs to be done to go with mods. Else people may just run out and get big valves before realizing what they have to do.

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post #86 of 493 (permalink) Old 12-24-2014, 09:01 AM
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Quote:
Originally Posted by MRDANGERUS View Post
FYI: To maximize the head flow in turbo applications, the exhaust valve should be ~90% of the intake.
The "early" (85-93) head (carry-over from N/A !) is at 86% (30.7mm Exh). Installation of the "later" 32mm exh valve, brings the ratio to 90.14%.
According to the information Tim just posted to the Turboesprit mailing list, the exhaust valve diameter did not change with the introduction of the Zues head. Just the intake valve was enlarged along with opening up the intake ports. The exhaust valve and I assume the exhaust ports remained the same in the S4s and Sport300 cars.

Steven DuChene
1974 Jensen-Healey w/Lotus 2.0L 907 with EFI & crankfired Ignition conversion
1985 Jaguar XJS 4.0L w/Getrag 5spd
1990 Lotus Esprit SE w/AWI monoblock wheels (wrecked)
1988 Lotus Esprit Turbo w/SE bodywork and burnt pistons
1988 Lotus Esprit Anniversary Edition w/Megasquirt EFI (NO CIS!)
1974 Lotus Elite (12th USA car off line)
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post #87 of 493 (permalink) Old 12-24-2014, 09:56 AM Thread Starter
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Hmm, what is the Zeus head?

I assumed that on "later" cars exhaust valves were larger.
I was wrong, sorry.

You're right, I checked the 1994 Lotus Service notes, page4, section TDI:

Intake valve
- S4 35.5mm
- S4S 36.5mm
Exhaust valve S4,S4S 30.7mm

That makes the ratio to diminish to 84% for S4 and S4s

Last edited by MRDANGERUS; 12-24-2014 at 10:07 AM.
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post #88 of 493 (permalink) Old 12-24-2014, 10:21 AM
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Quote:
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Hmm, what is the Zeus head?
This is what Tim posted to the TurboEsprit mailing list this morning:

The Zeus head was introduced in Jan 1993, along with the upgraded head bolts and the composite Goetze head gasket.

The head to block face remained the same from the Jensen-Healey 907 through the Esprit S4s Zeus 910, so any 9XX head will bolt to any 9XX block.

The intake ports were enlarged and re-contoured. The back side of the valve head was contoured to compliment the tulip port design to enhance flow. Standard/ generic valves of the same diameter won't produce the same results as the Lotus-spec valves.

Manifolds will mechanically bolt on interchangeability, but the later intake manifolds are port matched to the larger Zeus port.

The Zeus head's inlet valve diameter was enlarged 1mm over the previous versions (it's the 'big valve' version). The exhaust valve diameter remained the same as before.

Valve Diameters:
Inlet, 907 thru S4, pre-Zeus 35.47 - 35.65 mm (1.396 - 1.404 inch) All, except S4s/ S300

Inlet, S4s & S300 36.37 - 36.63 mm (1.432 - 1.442 inch) S4s/ S300 Zeus head

Exhaust, All 30.73 - 30.91 mm (1.210 - 1.217 inch) ALL

Zeus is the name of the company that cast the parts. When Lotus switched casting vendors, they also re-tooled the head and the block, switching from die cast to sand cast. They took that opportunity to make some running design changes, but none that affected backwards compatibility... except...

The Goetze composite gasket has a compressed thickness that is 0.5mm (0.02") thicker than the previous steel-asbestos-steel gasket (which is no longer available). That affects the overall Zeus engine assembly, and you asked about the Zeus head alone. So the following is FYI, and not Zeus head specific.

All else being equal, that extra gasket thickness raises the cylinder head by that same amount, resulting in a larger combustion chamber. The Zeus engines were designed to work with the composite gasket, so the cylinder block's deck height was cut lower by that same 0.5mm (0.02") amount, and then the liner seats in the block were cut that much deeper in order to preserve the proper liner exposure above the block deck ('nip'). In the end, Zeus engines with the composite gasket end up with the cylinder head in the original design-position, and with the correct nominal compression ratio. However, using that composite gasket on any older 9XX engine results in about a half a point lower compression ratio (8.0:1 becomes 7.5::1). There are no factory alternative, it is what it is.

All the Zeus engine assembly's dimensional differences are in the cylinder block's machining, and the gasket's thickness. Nikasil liners will interchange between pre-Zeus and Zeus engines (GT3 2.0 liter engines are a different set of design options all by themselves).

Regards,
Tim Engel

Steven DuChene
1974 Jensen-Healey w/Lotus 2.0L 907 with EFI & crankfired Ignition conversion
1985 Jaguar XJS 4.0L w/Getrag 5spd
1990 Lotus Esprit SE w/AWI monoblock wheels (wrecked)
1988 Lotus Esprit Turbo w/SE bodywork and burnt pistons
1988 Lotus Esprit Anniversary Edition w/Megasquirt EFI (NO CIS!)
1974 Lotus Elite (12th USA car off line)
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post #89 of 493 (permalink) Old 12-24-2014, 10:50 AM
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The route I went with my head. Enlarged intakes with with recut seats, opening it up a bit and stock exhaust valves. The machine shop Tim recommended to work on my head and is exceptional in that he is personally into performance and speed as a hobby and as a driver. So he understands the expense/risks vs results 1st hand.

It is not just about the spec ratio of valve size, it is about flow. Larger valves by themselves can obstruct minimizing gains depending on how they are cut in and other factors. For exhaust valves, a technique used by very skilled machinist comfortable doing such a procedure is to enlarge the port opening, reduce the seat width by maybe 50% or more, and do the exact opposite of larger valves which is to remove material from the valve radius a touch merging the valve into the reduced seat. You will probably need reduced thickness cam followers to get the shim range back.

Thats some spooky stuff as the seats help cool the exhaust valves. But performance and racing is about risk and results. To rich for my blood and not willing to pay the price as I'm just going for robust street driving. It is my understanding that the exhaust valves have a lesser overall importance in the descending value in the greater scheme of things to tweek. Not saying it does not make a difference, just that it is lower on the list.

Being sensitive to my meager budget. Tim and I had a discussion on what would be the most cost effective with an descending order of elevated to moderate return according to the type of driving and Esprit use I have exhibited in the past.

Head flow and porting makes a larger difference in an NA car than a turbo car. Turbos are using brute force to do what is required.

Cal H
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post #90 of 493 (permalink) Old 12-25-2014, 07:35 AM Thread Starter
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post #91 of 493 (permalink) Old 12-25-2014, 09:38 AM
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Yes, that's the place in the middle of the corn fields.

Also there is another place somewhere in CA that Tim said specializes in precise porting and flow matching. Like I mentioned before porting and flow has a larger impact on NA cars more than forced induction cars. It appears more cost effective to increase boost and collateral mods for higher return for the dollars spent. In the end Aaron's provided cost effective services for what I needed to be done. If price was no object, wanted to squeeze every last HP out of the engine I would have sent the head to CA. Along with a whole slew of other options for the entire car. But I have to live with real world constraints and budgets.

Just remember the engine like other aspects of the car must be tailored to ones driving persona and use. I was looking at a really enhanced BBK, the performance numbers looked impressive but was persuaded out of it with pretty convincing banter due to way I intend drive the Esprit which is robust street and occasional/light track. Still going for revised custom calipers and 2 piece rotors. Just not as aggressive with a compromise for multi condition/role capabilities. So I with that in mind I have chosen to be consistent and tilt towards robust or aggressive street settings in all aspects of the car. Unfortunately there is no gauge or standard to what robust street driving is, so it can have different meanings to different people. LOL

Everyone has to make a choice as to what is best suited for their driving requirements.

BTW I like how you handled it when presented with contrary evidence about the exhaust valve. It is so much easier to say "ooops made a mistake" or something like that and move on. I do that a lot when talking car with the MN guys as they are very precise and detail oriented people.

Cal H
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post #92 of 493 (permalink) Old 12-29-2014, 08:28 AM Thread Starter
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Hey, I'm not a politician, if I make mistake-I admit it.
One thing I know absolutely positively and for sure: I don't know everything! LOL.

Here is another "McGiver fix" which may save you some time and expletives when the necessity arise to replace tail light bulbs.

At least on my car, the plastic covers were held in place with... wing nuts, leaving no room to turn them. Major PITA to un-do the nuts while bending down and watching the World in upside-down view.

Here is a 15 minutes/6 dollars solution:

Get eBay item: 4 Pcs Black 5mm Diameter Female Thread Thumbscrew Grip Knurled Knob

4 Pcs Black 5mm Diameter Female Thread Thumbscrew Grip Knurled Knob | eBay

Drill a 3-4mm pilot hole trough the plastic starting from the threaded side. Next, flip the part and drill 6mm hole trough the plastic only (don't hurt the threaded insert).
Easy does it!
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Last edited by MRDANGERUS; 01-09-2015 at 04:13 PM.
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post #93 of 493 (permalink) Old 01-09-2015, 04:28 PM Thread Starter
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Constant tension clamps help preventing leaks and hoses damage/deterioration.
Aluminum components of the cooling system expand and contract all the time. Add to this the hose material set and season changes and you may have a leak.
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post #94 of 493 (permalink) Old 01-12-2015, 04:22 PM
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what intake hose is that (size)? and clamps?

Who do I order from?
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post #95 of 493 (permalink) Old 01-12-2015, 06:50 PM Thread Starter
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Look for CT9424 Constant Torque Stainless Hose Clamp Min 1-1/6" Max 2"
on eBay. Can be used w/silicone hoses, which have much thinner walls, like
eBay item number: 261219208259
.
For thick wall OE rubber hoses you want to order CT9428 (MAX 2.25")

Last edited by MRDANGERUS; 01-14-2015 at 06:40 AM.
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post #96 of 493 (permalink) Old 01-14-2015, 06:59 AM Thread Starter
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Trouble with acid spills

Battery tray on our cars does not have a containment tub.
It has just a drain hole, which does more harm than benefit. Instead of dripping on the ground, the acid spill wicks in-between the bumper and the rr valance corroding fasteners on the right side. If you ever try to remove the valance-you're in a big trouble.
Simple 4 dollar fix: acid mat
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post #97 of 493 (permalink) Old 01-15-2015, 08:27 AM Thread Starter
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being on the battery topic...
Since I bought it in 2013, I found a CTEC Multi US 7002 charger very useful. In addition to charging, it has several nice features, like recondition, maintenance and a bat charge indicator.
It is not a "rapid" charging unit, only 7 amp, but adequate to regenerate even completely discharged battery overnight. The crappy alternator on our cars keeps the battery notoriously undercharged, so you can use CTEC as a bat maintainer.

NOTE: Never use CTEC "Recondition" (desulphation) mode with the battery connected to the ECU and other on-board electronics. It may fry the underrated electrolytic capacitors on the PC boards or "flash" the ECU.

Here's a good info:
http://www.batteryfaq.org/
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Last edited by MRDANGERUS; 01-15-2015 at 07:38 PM.
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post #98 of 493 (permalink) Old 01-15-2015, 09:21 AM Thread Starter
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BTW: I didn't waste money on any exotic battery; I have just regular Wall-Mart Size 65 Duracell, 1000 Amp and 220Amp alternator. No problems, so far.
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post #99 of 493 (permalink) Old 01-15-2015, 12:44 PM
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Good tip on the charger, as I use one myself. If I ever use the recondition Facility, I'll remember to disconnect the wires first. And then remember the learning of the ecu afterwards.

Thanks,
Redfox.
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post #100 of 493 (permalink) Old 01-18-2015, 06:02 AM Thread Starter
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Being on the battery issue:
It is only prudent to replace the underrated brown wire (that tells you something, LOL), connecting the alternator to the starter lug.
Perhaps OE wire is adequate with old 90A Valeo, but if you upgrade the alternator-you MUST upgrade this wire to 4GA. Safety first!
Add couple star washers at the lug for a good contact.
DON"T use any copper based grease at the electrical connections (pic shows before the clean up).
Copper grease forms CuSO4 residue due to a galvanic reaction. Nickel-based anti- seize grease is much better.

Last pic shows the "anti-blow back" strap reduced to the knife-edge strap (by grinding) for better MAF flow.
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Last edited by MRDANGERUS; 02-14-2015 at 06:32 AM.
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