Lotus Elan

When is enough bhp enough?

PostPost by: 2cams70 » Thu Aug 24, 2017 12:03 am

The designers of the 997cc 105E Ford Anglia engine must have been really chuffed at what their humble creation morphed into. It surely is one of the most remarkable engines ever made. I don't think there is any other engine ever conceived that was as versatile or as significant to motorsport.

I wonder who they were? History records a lot about Duckworth, Chapman, et. al. but little about these guys.
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PostPost by: Sea Ranch » Thu Aug 24, 2017 12:16 am

Agreed! Would be interesting to read about those people and the development process.
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PostPost by: dunclentdr1 » Thu Aug 31, 2017 8:54 pm

I hope this graph and information may help.

Two S1 Elans:-

Red car - c125bhp, sprint cams

Yellow car - c150bhp, TTR fast road exhaust

If you look at the power and torque curves on the graph you will see:-

1 Pretty much the same until 4800rpm - more torque at lower revs in the yellow car
2 from there the yellow car just keeps going (for a while at least)

Insight? If you are only going to drive at 4500rpm or below stick with standard, unless you like some more torque. If you will be using revs, the upgraded engine is great - it feels and sounds very different, wow!!

Hope this helps.

David
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PostPost by: Certified Lotus » Fri Sep 01, 2017 11:47 am

Here is my dyno plot from my Twin Cam Weber head engine in my S1. I'm very happy with the HP and Torque curve. More than enough power for a street car. The only issue is a slight stumble below 2800 rpm. Above 3000 rpm and the car takes off like a bat out of hell with power curve all the way to the red line (and beyond but I don't go there). I have a large capacity air box so the engines breathes very well at high rpm's.

A friend of mine says the weber's need more tuning and others say with these cams they all do that. The only real solution is to take it to a rolling road dyno (4 hours away) with a tech who knows weber twin cams and have him play with the jets. Very expensive and time consuming with the outcome not guaranteed.
Lotus Elan Twin Cam Dyno Plot.pdf
Twin Cam weber dyno plot for Elan S1
(256.92 KiB) Downloaded 56 times

img_0740.jpg and
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PostPost by: rgh0 » Fri Sep 01, 2017 12:46 pm

Certified Lotus wrote:Here is my dyno plot from my Twin Cam Weber head engine in my S1. I'm very happy with the HP and Torque curve. More than enough power for a street car. The only issue is a slight stumble below 2800 rpm. Above 3000 rpm and the car takes off like a bat out of hell with power curve all the way to the red line (and beyond but I don't go there). I have a large capacity air box so the engines breathes very well at high rpm's.

A friend of mine says the weber's need more tuning and others say with these cams they all do that. The only real solution is to take it to a rolling road dyno (4 hours away) with a tech who knows weber twin cams and have him play with the jets. Very expensive and time consuming with the outcome not guaranteed.
Lotus Elan Twin Cam Dyno Plot.pdf

IMG_0740.JPG


What are the cam specifications? I cant find a listing for Kent Cams BLF48 that appears on the dyno sheet? it is hard to tune out the stumble for long duration cams over 300 degrees seat to seat as they all typically have a torque dip in the 3000 rpm area.

cheers
Rohan
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PostPost by: nmauduit » Fri Sep 01, 2017 12:59 pm

rgh0 wrote:What are the cam specifications? I cant find a listing for Kent Cams BLF48 that appears on the dyno sheet? it is hard to tune out the stumble for long duration cams over 300 degrees seat to seat as they all typically have a torque dip in the 3000 rpm area.

cheers
Rohan


Hi Rohan,

I suspect BLF46 is Burton's denomination of fast road camshaft (0.38" lift 280° duration, "in between CPL2 and L2") :

http://www.burtonpower.com/fast-road-ca ... 6-ltc.html
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PostPost by: Certified Lotus » Fri Sep 01, 2017 1:03 pm

nmauduit wrote:
rgh0 wrote:What are the cam specifications? I cant find a listing for Kent Cams BLF48 that appears on the dyno sheet? it is hard to tune out the stumble for long duration cams over 300 degrees seat to seat as they all typically have a torque dip in the 3000 rpm area.

cheers
Rohan


Hi Rohan,

I suspect BLF46 is Burton's denomination of fast road camshaft (0.38" lift 280° duration, "in between CPL2 and L2") :

http://www.burtonpower.com/fast-road-ca ... 6-ltc.html


That would be correct.
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PostPost by: rgh0 » Fri Sep 01, 2017 1:14 pm

I see I miss read the dyno sheet and its BLF46. Based on the low lift and 280 degree duration i would think a flywheel number is around 130 to 135 hp max at 6200 rpm in a 1600 twin cam with big valves is more realistic. The dyno result of 145 hp looks like a generous over estimate unless its a bigger capacity engine :D .

A 280 degree cam can be is tuned to remove any stumble at around 3000 rpm

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Rohan
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PostPost by: Certified Lotus » Fri Sep 01, 2017 1:21 pm

Engine built at Quick Silver Race Engines, one of the best race engine builders in the US with significant Twin cam experience. I think they would take offense to the comment of an over estimate from their dyno.

I had a 125hp engine in my elan prior, was nothing like what I have now.
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PostPost by: rgh0 » Fri Sep 01, 2017 11:00 pm

Certified Lotus wrote:Engine built at Quick Silver Race Engines, one of the best race engine builders in the US with significant Twin cam experience. I think they would take offense to the comment of an over estimate from their dyno.

I had a 125hp engine in my elan prior, was nothing like what I have now.


No offense meant to anyone ....just my observation on what I have found you can get in the real world in my experience with cams of this type, but without total build details I cannot say for certain what is possible or not. If it was done on a well calibrated engine dyno I am more inclined to believe it than if its estimated on a rolling road dyno which as you will see from some of the sheets people post tend to have significant over estimates of the losses.

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PostPost by: Certified Lotus » Sat Sep 02, 2017 11:41 am

Extremely well built and maintained engine dyno room. These guys build more race engines for just about every racing league than you can imagine. The ability to accurately measure the HP/torque on each built engine is an absolute must.

You are correct Rohan, without all the data on the specifics of the engine build its difficult to assess what the engine is capable of. Lets just say that Quicksilver knows what it is doing and the results show it (along with an open check book to achieve what I wanted). I was there during the dyno runs (A requirement of all my built engines) and watched them test to 7000 rpm on multiple runs (I know, that is break apart rpm on a stock crank. They told me not to worry as they are confident of their builds. I can attest that after 3000 miles on the engine I am not worried).

l1140629-1.jpg and


Quicksilver is building me another weber head twin cam engine for my 72 Europa that I am in the midst of doing a frame off restoration. Like my S1 Elan, it will have the right amount of HP/torque to ensure lively performance.

By the way, their machine shop facility in unlike anything you have ever seen. They do everything in house and it is so clean you could eat off the floor. This is no "local garage shop".
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PostPost by: prezoom » Sat Sep 02, 2017 3:04 pm

Sandy and company are a real deal.
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PostPost by: rgh0 » Sat Sep 02, 2017 10:38 pm

Certified Lotus wrote:Extremely well built and maintained engine dyno room. These guys build more race engines for just about every racing league than you can imagine. The ability to accurately measure the HP/torque on each built engine is an absolute must.

You are correct Rohan, without all the data on the specifics of the engine build its difficult to assess what the engine is capable of. Lets just say that Quicksilver knows what it is doing and the results show it (along with an open check book to achieve what I wanted). I was there during the dyno runs (A requirement of all my built engines) and watched them test to 7000 rpm on multiple runs (I know, that is break apart rpm on a stock crank. They told me not to worry as they are confident of their builds. I can attest that after 3000 miles on the engine I am not worried).

L1140629-1.jpg


Quicksilver is building me another weber head twin cam engine for my 72 Europa that I am in the midst of doing a frame off restoration. Like my S1 Elan, it will have the right amount of HP/torque to ensure lively performance.

By the way, their machine shop facility in unlike anything you have ever seen. They do everything in house and it is so clean you could eat off the floor. This is no "local garage shop".


Looks like a great engine build and test facility. I would sure like to know what else they did to get the 145HP out of a 0.38 inch lift 280 degree cam twink. But an open cheque book explains a lot :)

cheers
Rohan
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PostPost by: cudabenefast » Tue Sep 19, 2017 8:47 am

Rohan, I just found this thread and thought I would contribute the following as information. My engine is now running properly after a visit for a rolling road tune at Trevor Simken's in Shepparton on the recommendation of Elan Trik Bits (well worth a visit as the changes were very noticeable).

My engine is +30 thou, has standard valves but good valve springs, has steel crank and rods and QED pistons giving a CR of 10.5. The ports had previously had some work done and were not touched. It runs a standard flywheel.

My cams are Waggott 156 grind with 0.385 lift and 49/94 timing (interestingly when I asked Clive about this profile he said it should perform to around 8,000 rpm), the ignition is Lumenition, the carbs are standard (except for jetting) and it has the standard S4 airbox. The exhaust is a 4,2,1of not very generous proportions.

The "power" run (in fourth gear) with the airbox on yielded : max power was 76.6 kw at 5830rpm with a very gradual drop to 72.7 kw at 7420 rpm. Torque was essentially flat from 234 nm @ 2670 - 259 nm @ 5440 where it peaked. The torque values seem high relative to the power but the shape of the curve is more relevant to me and reflects how it drives.

On Sunday's EMR, our host who has Plus 2 with the full Spyder Zetec conversion and who followed us early, came up and "that car really goes, really goes!" I told him the above numbers and he said "well they are genuine horsepower".
Interestingly given earlier posts, we also did a run without the airbox and there was an increase in peak power (around the same revs!) of 3.5kw and an improvement throughout the range.

So once the Trik Bits sump/pick up are on (your sump will be home shortly :D ) I will for look a chance to run on a track without the airbox.

How much is enough? I would be very comfortable with my car as it is now with 170 - 180bhp. Resisting the urge to put my BDR into the Elan (for how long I can't say),the next steps with the TC will be a diff, bigger exhaust manifold, Jenvey weber throttle bodies and an oversize airbox.

I will see you soon.
Peter
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PostPost by: rgh0 » Tue Sep 19, 2017 10:53 am

Hi Peter

Glad you got the new baffled sump in and i will be interested to see how it works for you on the track, especially the right hander onto the back straight at Winton as that is the real test. I would be confident it will work well :D

Have a read of this web site to better understand the translation of rolling road test power to predicted engine power
http://www.pumaracing.co.uk/power3.htm

I get a maximum of around 100 to 105 kw (135 to 142hp) on my Group S Elan at around 7000 rpm on the rolling road at the wheels. This is around 170 hp to 180 hp with peak power at 7500 to 8000 rpm and is what I would expect from the fully developed high torque race engine in my Elan. My estimate is your engine with around 80 kw on the rollers without the airbox is putting out around 140 to 145hp which is about what I would expect from an engine with your specifications.

Note that on the rolling road the peak wheel HP occurs earlier than peak engine HP as near the top of the engine HP curve the engine power increase is tapering off but the losses are still increasing linearly so wheel HP starts to drop typically around 1000 rpm before peak engine power. With peak rolling road power at around 6000 rpm i would guess your peak engine power is around 7000 rpm which is what I would expect with a 310 degree .385 lift cam in a mildly ported head and pretty standard carbs and exhaust system and 10.5 comp ratio.

So lots of scope for more power in your engine before you need a BDA but that requires probably better porting and a higher lift cam and bigger valves and bigger carbs and exhaust and a few other more subtle changes to reduce engine losses :D

cheers
Rohan
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