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MikieP

93SE CAM question - 104 intake cam with which gear 104 or 107?

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Finally got car out of the shop of the do nothing mechanic into a shop of maybe will do something but they do lack a bit of knowledge. Question I need answered is: I have the 104 intake cam from JAE. Do I leave the 107 Intake gear or try to find the 104 gear for it? Goal is looking for best torque. Or am I a dufus? TIA. MikieP

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If you bought another green dot 104 pulley, then move your green dot pulley from the oil pump to the intake or exhaust, and then put the new green dot on the opposite, so you'll have a green dot 104 on both, and move your red or blue pulley to the oil pump.

 

If you only have the one green dot from your oil pump, then put it on the intake, and leave the stock on on the exhaust.


Travis

Vulcan Grey 89SE

My Lotus Photo and Projects Album

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Thanks very much! Will tell shop when I talk to them next as I am not sure what is present anymore, as it has been 19 months since I last saw these parts. Here's hoping....

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Goal is looking for best torque. Or am I a dufus? TIA. MikieP

 

For what I know you gain nothing about torque using two 104 cams, you loose some mid-range torque with some high rpm benefits... at least on the NA cars but I don't know the 910 Turbo engines.

Giorgio

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Roger that, Travis, just do not know if previous mechanic actually got the second 104 cam from Jae as they have no record of any purchase in my name or his. Any thing I should be aware of if I choose to do the 107 to 104 cam and gear change-out? I do have the 104 Intake cam i was told by JAE. understand I can simply swap the 104 from the oil pump to both intake and exhaust, if not already there.

Giorgio, my previous mechanic said the 104's were the way to go for improvement in both low end torque etc. but i just took his word for it.

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my previous mechanic said the 104's were the way to go for improvement in both low end torque etc

 

uhmm, I think it's exactly the opposite but again on the NA cars...

Giorgio

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With the kind "free" permission of my friend Tim Engel ( :unworthy: ) this would be definitive?

 

The more a turbo engine relies on boost, the less compatible it is with more valve timing overlap... it's difficult to build boost in the cylinder while both the inlet and exhaust valves are open.

For the early Turbo Esprits, boost was limited to 0.55 bar (8.0 psi) for the carburetted models, and 0.65 bar for the Bosch injected cars. For those low-boost models, installing a single 104 cam on the intake, and retaining the 107 on the exhaust works well. You loose a little off-boost power at low rpm, but the engine comes on stronger above 3500-4000 rpm. Overall, it's a plus, and I recommend it for the early 910s.

Using a 104 cam on both the intake AND exhaust further increases the overlap, delays boost build up, and costs more in lost boost power than it makes up in timing power. It's best not to mess with the exhaust cam's timing. If you do anything to the exhaust cam, then go with Kemp's high-lift version of the 107. That will keep the timing as is (no additional overlap) but the greater lift will help the breathing.

The 104 cam requires the 104 MOP/ green dot pulley. If you don't plan to upgrade to the green dot pulley, then don't waste your money on the 104 cam.

The 104 cam's greater lift (0.415") may (probably will) cause the stock valve springs to go coil bound. The best solution is to install a set of thin-wire valve springs from Dave Bean. In the UK, the common solution seems to be to cut the spring pocket a little deeper into the head. That works, but the thin-wire springs are the better way to go. You pay either way (either machinist, or parts), and the thin-wire spring's vibration dynamics are superior at high rpm.

Older 910's (pre-1992?) used chilled cast iron tappets. If you go with a high lift cam like either the 104 or Kemps high-lift 107, then replace the tappets with the later steel parts. They also have a slightly longer skirt that Lotus recommends for use with high-lift cams. Or... what I think they said was that cast iron tappets should not be used with high-lift cams.

Note that the carburetted low compression engines used cast aluminum pistons. They're barely up to the task stock, and will fail with very little hotrodding. More power will over-stress the cast pistons, and it doesn't matter if that power came from cams or boost. If you're going to hotrod an older 910 with cast pistons, start by replacing the pistons with forged 8.5:1 compression units.

*~*~*
The SE onward models add ECU controlled over-boost, which means more boost than the wastegate's mechanical setting of 0.65 bar. From there on up, it's easier and more cost effective to build power with boost and chipping the ECU. And as you crank up the boost, add a BOV and a Boost Controller, the boost-power lost due to increased valve overlap at low rpm becomes more significant.

A 104 cam on the intake side will still show an advantage higher in the rev range, but IMHO, investing your cam budget in higher boost and better boost control will produce a better return on your investment.

If you install the big valves from the S4s (ignoring for the moment the additional port work that was also done in the S4s), the result will be a loss of low-end power, but a stronger top end. A hotter cam carries a similar penalty... a loss of low-end pays for better top end. Combine big valves and hotter cam, and the effect is additive.

If you want an engine that pulls like a train from down low, with great throttle response in traffic, then stick with the stock valves and 107 cams. Add a BOV and stand-alone Boost Controller to improve low-end power/ throttle response, and use more boost to make top end power.

If you want peak power, and a strong pull at the end of the long straight on track days, then go with the big valves and a 104 cam on the intake.

But it's not all gain either way. It's always a compromise, and you must decide which end of the compromise you play in most of the time.

Regards,
Tim Engel

 

Great as always....

Giorgio

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Yep, that's true for the cam profiles, MikieP was referring to the cam pulleys.

 

On the USA cars, in order to make sure they could meet emissions, Lots put the red dot and blue dot pulleys on the 910 engine to retard the timing.  The 104 pulleys are what should have been on the car, and were provided on the UK cars.


Travis

Vulcan Grey 89SE

My Lotus Photo and Projects Album

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Thanks to both of you. looks like I may have buggered things up then by listening to my old mechanic. now I am not sure what he has done. Will have to go to new shop and find out precisely what cams are present an what gears are there.... Here is the complete rundown on parts to go on the car;

 

Welch's latest turbo (March 2013), his matched primaries and secondaries, and his ECU.

HKS VI boost controller

was billed for cryo treating the transmission - not sure it was really done though - any idea how i could tell by looking at it?

was billed for cryo treating the valve springs - again, not sure.....

ported head

LSD installed in the tranny

Silicone Hose set

Blow Off valve

S4s clutch Kit from JAE

JAE Rod bearings

JAE Main bearings

JAE blue cam belt

K&N Air Filter

Alunox SS321 Headers

JAE ring set

mechanic states I now have Honed Cylinder liners

mechanic states I now have bushed connecting rods

Am I to understand that i should have the 107 exhaust cam, the 104 intake cam, and both 104 cam pulleys?

 

Advice for getting the most out of what i have, please? TIA

 

MikieP

Edited by MikieP

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More questions:

 

I am considering removing the EHBV i think it is called with a JAE insert. Should I consider the Alunox Stainless cat and exhaust currently being discussed here in, and if so, std size or up it to the 3" tubes?

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Hi Michael

From my experience it sounds you are going in the correct direction, But there are so many things

that influence the results you need to concentrate on keeping a tuning balance..

I have found using standard cams timed at 104 104 will give you low down torque and top end

capability when used as part of a tuning package.

To take out all the variants on an engine that has been worked on, I always fit vernier

pulley's, This will enable you to set the cam timing you require for your engine spot on, not to the

tolerance of the pulley and head skim...

With reference to the post turbo exhaust side, Bigger is better, I have posted in depth info on this 

 somewhere, outlining the reasons and advantages. 

I have seen and heard the post turbo Alunox system running on Mark Kassims Esprit, It looks and sounds

very nice with great fit quality...A good choice... 

Personally I run bespoke 3.5 inch with straight through box. This allows my turbo spec to breath freely..

 However as stated balance is important. VE, Overlap, MAT , Boost level and gain. induction geometry and

laminar,Exhaust all work as one, and influence each other,    So don't loose focus on the bigger picture when

concentrating on one area..  

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Hi changes,

 

Thank you for your insights! Should i return to JAE what I have been told is a 104 Intake cam then and just wait for the 104 intake pulley and continue to use the stock intake cam?

 

If i keep the stock cat and exhaust how much would i impact the totality since the ALunox piping is relatively small compared to the 3" and up. I am required to pass emissions testing yearly where i live...

Edited by MikieP

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I guess what I am asking is what do I need to determine I have in the way of parts listed, such as:

 

which cams I actually have on hand, actually unknown

which cam pulleys i have on hand, actually unknown

 

and then what i should have in hand to get a well performing coach at both mid and high rpm. looking to get about 325 to 375 whp out of what i now have in hand as a guess.

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Hi Michael.

I use the stock SE cams for both inlet and exhaust.. both timed to 104 with vernier pulley's..

The verniers are not that expensive and will enable you to get a very accurate 104 timing..

The standard 104 pulley's will be limited in accuracy to your head skim and gasket spec...

I can not comment on the JAE cam as i have not tested any, However what is achievable with

the standard cams is the reason why i have not changed them... 

 

The stock cat is history and will diminish power greatly.. If you need to run cat use sports high

flow only...I also have to pass emissions test each year and do so without a cat...But to be fair

other changes have assisted the burn quality.

 

Regarding what cams you have on hand,, refer to stamping on the pulley end circ.

Regarding what pulley's you have on hand,,, refer to the colour timing dots against EX or IN..

 

325--375 WHP will need a bit more investment in the injection, ignition, induction, and turbo area's.

You will not achieve the required sustained VE for that power without other changes.. 

325 bhp at the fly is achievable with the drive qualities you require and the parts you are using..

however you may need to look at the ECU.. and consider you will be entering the limit of your

gearbox after that..

Quite a few have reached the 350 bhp mark in short bursts, but under sustained aggressive driving

the power falls away with the turbo temp  and loss of VE.. This is usually due to elevated boost levels

and the incapacity of the ECU to control fuel.. The results are excessive heat in the combustion chamber

leading the failure..

My advise is not to look for a power figure, Just work the ingredients within your budget until it performs to

your requirement... Getting the top power figures and keeping it drivable throughout the range is expensive and

a very drawn out exercise...  

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"was billed for cryo treating the transmission - not sure it was really done though - any idea how i could tell by looking at it?"

 

You can never tell if your transmission was Cryo'd after it was done.  The problem with the whole industry (and I include heat treaters in this) is that they are in it for the money without ever investing in the science.  Cryo means -300DEG and below.  Then you have to figure that if your transmission wasn't taken apart did the entire ensemble reach those temperatures and THEN did they use the prescribed time for treatment (including ramp down and ramp up times that are crucial!)  Also, most self proclaimed Cryo processors use machines that spray LN2 into the cavity and create even more stresses they are trying to relieve in the first place.....

 

Oh and BTW...Listen to Dave...when I build my rig I hope he's willing to share his insights!


If the only thing constant is change, then why do we resist change the most?

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Nuts! Starting to wonder if i have done anything correctly... Thanks for the heads up and will at least perhaps stop the new shop from opening it up to look at it to see if anything could be seen... Again, Nuts! lol

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One other issue, I have been told the the new Welch Turbo kit from March 2013 includes the Welch ECU that supposedly handles the extra boost mapping. Dunno.

 

Given the parts I have listed earlier on hand, can anyone make a step by step process that I could follow, please? Off for the weekend to let all this settle in and try to formulate a reasonable process. Shop says they will start on the car sometime in late September as two other Esprits are ahead of me, so I have some time to come up with a scheme for them to follow. Cheers.

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Update.

 

Treasured Motors has built up engine with S4s clutch attached, less the head, which has leaks in every valve seat due to apparent poor machine shop work authorized by previous shop. Tears to eyes to see it even that far along. Turns out current Turbo is a race sized one and that may have to be down-sized perhaps. Been a long two years without this in my driveway. More later.

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JG,

 

Update is:

 

Received car back from second shop last Friday! Drove her home about 45 miles somewhat energetically - No A/C functioning although they said they replaced the Schrader valve to get it working. Engine ran quite strong though I could only get about .67 Bar boost on the AEM boost gauge (it has the S4s ECU chip in her + 3% extra fuel from WC Engineering). I was told it was getting 1.1 or so. Oil pressure seemed to be low and oil light flickered whilst at stop lights and always seemed to be lower than I remembered it while at speed but indicated above minimum range so I attributed it to the break in oil. So I decided to drive it down the road to our soon to be retirement house about 110 miles away, mostly on only 50-70 mph roadways. Almost there: alternator belt started screaming then broke. ABS light came on later, Fan Fail lit up. Cracked rear side light, both door gaskets torn along bottom edges, never before gas smell inside cockpit, Passenger side fuel door would no longer open though I could hear the plunger working, rattle in engine compartment during deceleration.....  Parked her in the garage and the shop came down Sunday to take her back to the shop. So much for my 2 1/4 year wait to drive her down the road and the $24K engine rebuild I did not ask the first mechanic to even do, effort so far.

 

As to the build: It appears I now have a 107 cam if I can believe the paperwork, green dot pulleys for both intake and exhaust. The turbo is a complete unknown but might be a race built one off the shelf of the first mechanic supposedly built up by WC Eng but he stated he did not recognize it as his. It is definitely bigger than stock without question and using V-Clamps now. Will think about removing the CAT after I register and get her inspected in my soon to be new home state (Delaware) once I finally move. EBPV now gone as well.

 

Still not sure what to do about the stolen aluminum gas tanks Jaime Goffaux stole from the car as the ones he put in where full of rust particles and had to be sucked clean couple of times to even get it to idle, and, just who's, and in what condition, transmission did he gave back to me in my proper case has yet to be determined. Found a company if Florida that has them for $750/set though not sure they are the correct ones for my car - but I can not currently afford to have the current shop install them.

 

But it did run much stronger than I remember her doing back in February, 2012, I suppose due to the SS Alunox header, a (non-)WC Engineering Turbo fraudulently sold to me by first mechanic (Jaime Goffaux) as John stated he never sold it to Jaime Goffaux; a very badly done and now correctly redone ported head, RC injectors I hope are a matched set and a real WC S4s +3% chip, etc.! And so the story goes on. At least the Cam belt did not crap out, yet.

 

Cheers!

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Wow... A mix of emotions and rightfully so... Congrats on the engine imporvemenfs and I'm also sorry to hear your eventful voyage with your "newly" worked beast... :/

At last she is home safe and sound and next you can do the final touches with the proper care that she deserves!

I also had to replace my gas tanks. I used the guy who you're talking and yes he is here in Florida (where I live). If it makes you feel better "yes" they are exact replicas of the OEM ones, but lighter and prettier. Definitely an upgrade from the old ones.

Good luck with your car and keep us posted!

PS: You prob have a t3/t4 hybrid turbo in your car.

JG

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Is this a t3/t4? Also, went back to shop and still there. Trying to determine why boost drops off erratically from 1.2 bar back to .67 and other niggles. Maybe another day, or year for the alloy tanks and the A/C repairs.

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