412 BHP...THAT WILL DO NICELY......

[Bentzion]

I feel like a one man posting machine...But i had to share this with you Dave... and the rest of you lot!

 

https://www.facebook.com/APSMotorsports 

 

The Jenvey's are what I was thinking in the posts above..Although you are sticking with the original layout for now.  These will supposedly bolt right up to a 900 engine.

 

Awesome to see the work being done with this engine! 

[MrDangerUS]

Bentzion,

 

Linky -no worky!

?

[MrDangerUS]

Another good place to get a full "fat lip" velocity stacks of a suitable size is here:

 

http://stackinjection.com.au/main-group-1/velocity-stacks/45mm-diameter/45mm-id-x-50mm-long-89mm-bellmouth.html

 

They are 45mm ID @ rear and 76mm OD @ front (the listing shows 89mm, but it is a typo error).

 

76mm stacks may package easier in the confines of the plenum cover, providing you add the plenum spacer.

 

1.5", even 2" thick spacer could be  fitted on the SE and later cars, but on pre-SE only max= 1" is feasible.

Edited November 9, 2014 by MrDangerUS

[Bentzion]

https://www.facebook.com/APSMotorsports

Edited November 9, 2014 by Bentzion

[CHANGES]

10k miles Problems Encountered…!!!

Is that the sound of the old death rattle?

 

There are a lot of interesting developments still to be tried on these 910 engines, the

plenum being one.  Those recent illustrations show how much the flow dynamics can

still be improved, increasing quality and potential. I have undertaken some more

changes of my own which I will test and be covering later..

However I did say at the beginning of this thread some years ago that I would keep

everyone informed on the positive and negative side of developments..

 

Time for some negative.  Although this was originally built for reliability rather than

out and out performance, I found that as things developed the boundaries got pushed

and the original focus got clouded. I found myself exploring more what improvements

could be made rather than consolidating the original 412… As a result just prior to the

10k miles mark I encountered an oil temp issue after yet another spirited run, this lead

to pressure drop and sick sounding donkey. There had been a strange unexplained

anomaly for the last 3k miles which now seems can be answered.  To cap it off at the

same time a clutch thrust bearing issue (disintegration) joined in…  I decided it was

time for a full strip inspection.  What I found was I suppose not surprising considering

the hammering it had, but still needed properly explaining.… I reframed from posting

details until now, so I could confirm all the possible reasons and explore the best solutions.

 

 

As you see from the pics above the big end bearings have broken as well as worn out..

 

What we must not lose sight of is that although this engine eventually produced 425 bhp

it was still mechanically a stock engine, same as all SE’s out there, built very carefully to

Lotus specification using stock parts only . The fact it took the abuse it did for so long just

proves how good they are and can be..

On examination other components that suffered structural failure were the con rod’s.

These had slightly stretched big end section and the crank had some deformation. All

unfortunately now scrap.!!!

 

 

The con rod above shows the heat generated was enough to blue the steel.

The rest of the engine was spot on as build spec. virtually no ware at all.

 

Conclusions based on investigations  

 

It seems it was a combination of factors that when drawn together resulted in the

failure. Some of these factors were inherent others introduced by me as part of

the dynamic air flow tuning. Component weight (reciprocating mass) was a major

factor. That with the higher final compression ratio and available oil pressure at the

big ends were its death knell.  In short the stresses introduced by the power produced

exceeded the stock unit design limits.

 

Apart from the component weight issues, oil pressure at the ends also came into play. 

The standard static clearance on the mains can get over-sized or at least generous

when the block is at working temp. Studies have shown that the main bearing housings

can expand by at least 0.003” at 82 degrees. This allows oil to escape at the mains

causing a flow and pressure drop down stream….at the big ends!!!  On its own this is

not an issue, but when the loading on the crank pin has been increased the chances of

failure become greater. As the gauge reads the pressure up stream of the mains it may

not be apparent what is happening..  That was where my anomaly came in, I now see it

was a clue.

 

 So if we take a lower oil pressure than the gauge indicated, introduce extreme loading

from final C/R I was running, along with the stock reciprocating weight mass, add that to

regular rpm’s over 7k, along with 85 dyno runs and testing sessions (As demonstrated in

the Alunox video),  then the outcome I suppose was Inevitable.

 

Which way to go from here?

 

Although £ sign’s were flashing at me I could not help but see this as an opportunity to

develop changes within the mechanical components and explore the wider possibilities.

These would have the primary focus on rectifying the load and oil issues that caused

the premature failure.

 

 The second and overlapping developments would be to study and implement changes

to reduce parasitic loses within the unit itself.  The catalyst for the Inspiration on these

developments came from data forwarded to me by member MR ‘D’. So credit to him for

that, ‘’Thanks John’’.

 

The third area for development consideration would be to capitalize on all the positive

points within the 412 project. Using all this and the plethora of information gained during

the endless testing.  This can now be used to implement more technical changes

integrating the flow dynamics with a new combustion format.

 

The fourth area is the clutch. The latest bearing disintegration was accompanied by a

fried drive plate. This all due in main to the tall 1^st gear ratio on the GTO box.  The

ceramitalic paddle plate was not designed for road use with that sort of ratio, so only

lasted 3.5K miles. The thrust bearing failed due to extra clamp loading needed, along

with heat from slip needed with 1^st         

 A lot of changes needed here to find a system to take the projected torque that has a

road drivability and lasts at least 20k miles.. In depth consultations with AP Racing have

been invaluable.

 

The final area to be looked at is the driving stability under load. The Esprit was starting

to twist and squirm, brake traction in high gears, especially in damp conditions. I still

believe the factory geo is spot on for these cars, but the changes made to the power

train in this case seemed to have tested the original design limits. So some changes

are being made to re-stabilize along with traction aids.

 

When completed hopefully all the deficiencies should will have been addressed,

improvements made, but still staying within the spirit of the Esprit and the 910 engine..

 

I have spent the last twelve months developing all these concepts and now in the testing

stages before finalizing. When completed I will post details to cover each section over a

period of time or when questions attaining to an area are brought up..

 

Dave

 

[Bibs]

Ouch! Have you seen these rods that Garry Kemp uses on his engines? Much lighter so less inertia...

 

[PaulEspritGT3]

Excellent article Dave (and all your work on the car) – I’m sorry about the damage and its cost but I find what you are doing very interesting.

 

My GT3 is still going better than ever since the work you did on it last year.

 

Paul.

[CHANGES]

Hi Bibs,

 

Yep looks familiar, 

 

 

The weight savings on the whole reciprocating set up were massive, Total across

all cylinders came to just under 4lbs..!!!!

This was the major part of the primary focus to reduce the mass loading..

The dyno testing and  performance figures, as far as it can go at the moment, are done.

I will pick it up tomorrow and be able to post some figures over the weekend for those interested.

 

Paul, pleased things are working well, I hope to be out and arranging again meets soon..

 

[Vulcan Grey]

Dave,

 

Did you do Gary Kemp's recommended mod of restricting the oil feed to cam towers?

 

[CHANGES]

Hi Travis,

 

Yes,  I chose to go with the 2.5 mm option this time ,   what size did you settle on ?

 

 

[CHANGES]

After 3 weeks I retrieved the Esprit from NMS today completing the initial set up and testing .

Unfortunately it was not all plain sailing, but that is just the nature of the beast..

The lower maps were fine although we were having trouble turning the boost down enough.

This was a problem I had before but it did not affect the drivability so ignored, however as the

new mods kick in it has gone a bit higher, I think it will be fine as it comes in more gradually, I will

know more after road testing..

The real downer was when we went for the  higher boost settings for the build spec.

The torque exceeded expectations and went beyond the capability of the new Cosworth spec

clutch I installed from AP Racing. 

This was a major disappointment as so much work/cost went into getting it to fit, but that is an 

area to cover later.. This does not mean it can not be used, just that we have had to turn down

the engine power to the capability of the clutch.. I have spoken to AP and they are looking into

what options are open..

What this does mean however is we can not get the full potential out of the engine and fully test

all the changes I have made.

We have had to settle for 461 BHP with 450 ft lbs torque for now..    (436 WHP )

 

 

This is a step up in power / torque level , using slightly less boost than before.

In the new engine spec I have made changes to the compression ratio, lowering it. This means 

that even though the power figures are higher the final C/R / lb of boost is lower than we had previous .This is one area i was hoping to exploit which may have to wait..

 

 

Graph 2 gives the comparison between specifications. The black line is the old figures.

You can see we are bringing in the boost more gradually but the power comes on stronger

from 3500rpm.. 

 

 

Graph 3 gives the torque comparisons, along with the Lamba. The black Lamba line is showing

we have it a bit richer higher up the rev range. This will be changed after a break in period for the engine.. when done it should help flatten the torque curve a bit after 5000 rpm 

 

So for now i will reassemble the rest of the Esprit and get some road testing miles in, whilst

waiting for feedback on the clutch options.. 

 

  

   

 

 

 

[Barrykearley]

Now that is what I call hardcore......

Love it - I bet you enjoy that round a track - keep up the fine work

[Vulcan Grey]

Hi Travis,

 

Yes,  I chose to go with the 2.5 mm option this time ,   what size did you settle on ?

 

 

 

I think I did 0.125" or 3.2mm

[CHANGES]

Now that is what I call hardcore......

Love it - I bet you enjoy that round a track - keep up the fine work

 

Thanks for the acknowledgement Barry,  But its not built as track car its a daily driver, which is why

we have the clutch problem..' track power road clutch'..  I moved back to an organic drive plate, for

drivability and hopefully longer life.. but it seems I need a re-think there if i want to use all the torque

on the road..Uhmmm..  

[paulob1]

I have only just popped into this thread, fascinating.

 

I rebuilt three Ford racing puma 1.7l four pot engines....first one was with 320 bhp, superb.

second was with 230 bhp n/a and 100 bhp with nitrous oxide, what a chore that one was,...

third is just a mild 300 bhp.  very similar to a lotus engine...

 

the 320 bhp engine was very close to perfect but i wanted a bit more power...so we headed for bigger turbos and larger manifold, just going for dyno next week...hoping for 350-360, 

 

but what interests me about your curve is with our turbo we have aimed to reach max power just under 7000 rpm, max revs are 7200, so we have a continuous smoothish climb to max power over the full rev range...yours is very much geared to mid range and tails off at higher revs, so that means you have to up shift much earlier, it must make it very tricky to drive, or does it...

 

I know you have changed the gearing and perhaps its because of this unusual power curve that you have had to do this.

 

on my frp's wheel spin in first second third  fourth and fifth is possible if i see any moisture, front wheel drive, I have destroyed the bearings in one box, being rebuilt...in the dry i basically take it easy in gears 1 and 2.  My plan this time is to have the gearing the same again but to beef up the bearings so I can hit the power a bit quicker in first...she will always slip her wheels in first..

 

however as my gearbox is set for 7000 rpm and 140 mph that is all I get but gosh it gets there rather quickly and that is with 320 bhp...personally if i ha d a car that could get to 160 or 200 as fast i would likely be walking everywhere in double quick time...

 

given your knowledge why did you go for such an unusual power curve...

[paulob1]

ah stupid me I did not read it properly...now i understand...thats as i would have expected....I should have read it more...

[Barrykearley]

Dave

I can't believe you really want more power for the road. My gosh that is hard core

The wife came out in mine yesterday - and now refuses to go back in it - too much whooshing and the acceleration makes her feel sick!!!!

Gonna have to order another woman for passenger seat use!!!

Good luck with the rebuild

[CHANGES]

Hi Barry,

Its not that i want more power for the road, there is plenty for that, Its more about completing the

task... I altered the specification to provided new abilities for boost and flow while fixing the

component weight issue. Because of the 450 ft lbs limitation on the clutch the targeted 1.75 bar

boost and 8000 rpm can not be tested.  A bit like having a great HI FI but the speakers crap out

at 75% volume..  

All of that aside, drivability and smoothness is still a major factor, without that it might as well be a

track car, which is not the objective..

 So road testing and consolidation at this level will be priority for now...

 

Sorry to hear the wife not so keen, I think we all get a bit of that, Its just a man thing..      

[CHANGES]

Development details    part 1..

The dyno data shows that we have produced more power with slightly lower boost and

lower final C/R than before. In fact we produced over 400 bhp with a fraction over 1 bar

boost on the low map..  There’s food for thought..  How was it achieved..?  What was changed..?

 

 

My initial aim was to overcome the reciprocating weigh problem and make the rest of

what had already been developed as efficient as possible..  I had previously established

that contrary to some opinion flow management on a turbo engine can have major gains..

So maximising this along with other changes would explore the wider possibilities.   

Firstly the reciprocating weight issue. To insure reliability and prevent a repeat of what

transpired, new pistons, con- rod’s and crankshaft were going to be needed.. Whilst

replacing these components there was a few design changes I wanted to introduce,these

would allow me to alter the combustion format with rod length ratio, deck height and C/R.

 

 

 

The new custom made pistons would have a larger bowl with deeper valve recesses. The compression height was reduced and a smaller wrist pin used. The piston height and skirt

length has also been reduced and treated with HSC3 low friction coating, (as part of the

parasitic loss reduction exercise). The crown has a ceramic coating for extra heat protection..

plus a major reduction in the overall weight compared with std.

 

 

The rods as we said earlier are now the H section, these will better handle the reciprocating

forces. This design was chosen based on the projected HP and RPM requirements. I have

also increased the overall length but still been able to make major weight savings. The

length change had two elements to it, one was to change the combustion format, the other

to change the rod angle reducing the friction loading between the cylinder wall and piston..

(This again as part of the parasitic loss reduction exercise).

 

 

 

The crankshaft is now a billet steel EN40B Nitrided unit X drilled. Manufacture for an explicit requirement with larger than std mains journals. The big end journals drilled through to

lighten them.. This is a much stiffer unit designed to take stresses my engine produces.

Slightly heavier static weight than the std unit but balanced with the reciprocating parts.

The larger journals are to tighten up the clearances and improve the flow to the big ends.

The tight clearance could cause premature ware on cold start, so I have also installed an

oil primer system to generate 2 bar oil pressure before initiating starter motor.

All of the above along with the fly, clutch and pulley’s etc have been super dynamically

balanced to a tolerance of 1/10^th of a gram..  This includes all the fixing bolts which are

now position sensitive, so numbered.

Some may say this is all a bit extreme, but I say the devil is in the detail.

 

 

So what are the effects and how does this all actually work..?

The weight reduction will reduce the mass loading on the crank well within new spec limits.

This will not generate more HP, but will improve throttle response.  The ratio

between the rod length and stroke will affect how it performs. Point one is the

friction, this is straight forward the longer rod reduced the angle and places less stress

on the thrust surfaces. Point two is far more technical and has to be calculated while

accounting for all the flow data.  (In brief) By using the longer rod we increase the dwell

time at TDC. This is all part of the new dynamics where the piston will move slower in the

upper part of the stroke cycle. This will maintain a longer state of compression, keeping

the chamber volume small longer thus providing better combustion with higher cylinder

pressure in the early stages of the down stroke. When we combined this with a lower

static C/R and the new flow volume / velocities of my induction system it allows it to

become far more efficient than previous.. 

[paulob1]

love it all so can you build me one...

[Barrykearley]

Hardcore - really is - love to see we do still have some engineers in England

Keep up the hard work - and spending!!! Will be looking forward to the updates

[paulob1]

but still seems a lot of work when you can get a zetec ford engine these days running 500 plus brake horse without all these tricks...and I can get 350 bhp out of 1.7litres of ford engine without much bother...

[Barrykearley]

Yeah - but that has been done........

Think dave likes a challenge more than I do.......

Wonder what a zetec in an esprit would give 0-60 ??

[molemot]

You've missed the point, Paul....Dave is into treading where nobody else has trod....that's where the fun is!!

[CHANGES]

Development details part 2

 

Carrying on from the main bearing mod to better control the oil, draws me into oil

management as a whole.  Whilst studying the oil post big end, it was apparent the

crank case contained a major oil cloud with excessive splashing from the moving

parts. This dense cloud is constantly whipped aerating the oil droplets generating

heat and drag.

(A major parasitic loss)

 

 Within the standard engine most of the oil returning to the sump does so by dropping

down past the crank and on the inner walls of the block, whilst doing this it is slapped

around and agitated by the rotary parts as is the surface of the oil in the sump from

spray and windage.  All of this creates excessive aeration of the oil.  I also noted that

all the oil returned to the centre of the sump with no actual circulation of the volume

contained behind the baffle plates, in fact it appears that 50% of the oil volume is

relatively stagnant serving only to maintain a level not actually circulate.  This gives

less time for the oil to de-aerate fully before entering the cycle again..

 

 

Pic 1 shows the area within the block where oil drops back

 

Pic2 shows in yellow box’s the relatively stagnant area , red the active within the sump

 

 

Pic 3 shows the same but on the standard baffle plate

.          

Most modern engine designs have considered these factors and incorporated windage

trays and some form of crank scrapper to minimise the negative effects. The 910 has

none of this which opened the door for me to explore the possibilities.

The first area to address was the crank scrappers. There are several designs used to

achieve the same objective, but the closer they are to the crank the better they work.

I chose to go with the more extreme version which are designed with partial interference

fit. This is possible as the edge of the blade is Teflon. When the engine starts running,

the rotating components will shape the Teflon to the perfect profile giving the minimum

clearance

 

 

These scrappers will have a dual action. 1. Is to remove excessive oil from the periphery

of the con rod and crank. This will reduce the excessive amount of oil splayed around the

inner crank case, also removing an unnecessary film from the surface.   2. Is to create a

wind break within the crank case. This will reduce the massive turbulence and help

manage the windage.

Whilst installing these an opportunity to redirect the oil and open up the baffled area to

full circulation became possible.  Instead of letting all the oil drain back into the center 

sump as before, a large percentage will travel through the wall of the main bearing

housing into a previously unused cavity within the housing itself, as shown above.  

From there it will pass over flat surfaces and through de-aeration tubes into the wings

of the sump. At the same time the oil return from the turbo was directed into the wing

instead of the center. 

All of this will allow me to use the full oil capacity creating a slower circulation cycle time

and better management of the oil system. It is not designed to remove the oil from

splashing around to do it much needed job, but to remove the excesses and calm the

windage effects thus reduce drag.    

To further enhance, I designed a fully baffled sump to prevent slopping under braking,

acceleration and cornering.

pic 1 shows new baffle tray inverted.

 

 

pic 2 shows it in position within the sump

 

 

This does however create a continuance of the flat surface from the front of the sump

where agitation from the cranks rotational windage on the returning oil in that location

could be a problem. To resolve this I also designed a windage tray to go between the two.

Pic 1 show how it sits within the baffle tray

 

 

pic 2 shows how it attaches to the block.

 

 

With the extra volume in circulation the oil temperature will now need a better control to

reach and maintain the working temp. To do this I fitted a thermostat sandwich plate to

the coolers and a restrictor for engine RPM below pre-set temp.  To tidy things further a

remote filter was also fitted, this gives easy access for changing and also generates a bit

more room where needed.

 

By creating a form of barrier with the crank scrappers to control windage I also technically

divided the crank case into two sections. This could create a problem with the crank case

breathing which is controlled by a vent in the lower section of 3-4.  It is very important that

crank case pressure is kept to a minimum. This is more difficult when not using the induction

system as a vacuum as in std. set up. To get around this I tapped into a facility already

available but no longer used, 4 holes, one under each cylinder in the upper crank case area.  

By opening these up and venting into a catch tank I can restore any imbalance created with

the changes made.

 

 

Finally the oil primer system. As said before this is to protect the tight tolerances on cold

start by introducing oil pressure first.. I have installed an electric pump capable of 4.75 bar

flowing at 11.5 ltr/min. This is fed directly from the sump through one way valves and its

own filter system into the main oil gallery on the block.  When the ignition is activated the

pump first primes the engine up to 2 bar pressure which takes about 5 seconds, then

automatically switches over to the starter motor in one action. Once the engine is running

the ignition system remains switched to the starter motor until oil pressure drops below 2 bar.

At this point it will reset to a prime cycle for start-up.

    

None of these processes listed above are new, just the application and format within the 910 engine.