Lotus Europa Forums > The Paddock
807/TS DD, Auto-X, Hill-Climb build.
Richard48Y:
What I sent to Delta Cams as reference for my new grind.
This may be what I have now?
The 807-12 and the Euro 17TS-844 engine (cooking versions of ~125HP) used a valve timing of 40/72/72/40.
Valve lift: Inlet - 9.6mm; Ex. 9.5mm
This is off a photocopy from Franco-American Imports in the early 80's, it's was sourced out of the Renault racing manual for 12/15/17. picture below.
7701452043 - R12G
Inlet Valves
opens BTDC 40 deg
closes ABDC 72 deg
Exhaust Valve
opens BBDC 72 deg
closes ATDC 40 deg
There was also a more competition oriented cam that some guys are running on the street.
7700524884 - 1600cc Racing
Inlet Valves
opens BTDC 53 deg
closes ABDC 83 deg
Exhaust Valve
opens BBDC 83 deg
closes ATDC 53 deg
From the UK Renault engine expert, Salv Sacco.
A lobe profile that gives 290 – 296 duration somewhere close to these dimensions – (at cam lobe not at valve)
Total lobe height 0.285 – 0.290” lift
54 degrees from peak - .070” - .075”
If that can be ground at 108 LCA and using a theoretical rocker ratio of 1.52:1 and a valve clearance of .015” you should see something very close to these figures:-
Total valve lift = 0.425” Lift at TDC = 0.099”
Set cam timing to show either an equal lift on both inlet and exhaust at TDC, or with .005” - .010” more on inlet than exhaust.
I find this gives a smooth idle, really strong mid-range with a 7K peak.
Start line RPM I guess would be around 4500RPM
All the above is based on what I have used and it works for me!
Most of the folk I have conversed with feel this one is too much for the street.
http://www.catcams.com/products/camshafts/datasheet.aspx?ENGINE_id=194&CAMSETUP_id=752&Language=english
intake exhaust
camshaft data:
lash ramp: 0.40mm0 .40mm
duration @ 0.1mm: :280° :280°
duration @ 1.0mm : 236° :236°
valve lift : 10.00mm :10.00mm
cam lift : 6.25mm :6.25mm
lobe angle : 110° :110°
timing @ 1.0mm : 8° / 48° :48° / 8°
valve lift @ TDC : 2.15mm :2.15mm
jbcollier:
Sal knows these engines inside and out. I would always go with his recommendations.
Mecky:
Hi Richard,
I'm now building my second engine of this type, which you also have. I'm wondering that you are talking about small budget, but use forged Wössner pistons with Ø77,8 mm bore. They are high end. It's almost a pity that you want to machine them for lower compression ratio. There is also another set of competition pistons available for that bore. These were used by works-supported Renault Formula Renault Europe teams in the 70s. Renault supplied a tuning kit back in the day, which was called the 160 HP kit (SAE horsepower, but nonetheless). I used to have a set of those to spare (picture attached), but gave them away a week ago, because I want to take it one step further with my engine and go for the Wössner pistons with high compression. I'm aiming for 12:1, but my engine has the 318° cat cams shaft with adjustable chain wheel and double valve springs. So not at all driveable on the road.
I have also had good experience with the 310° cam shaft. This brings a huge torque from 4500 RPM onwoards, but not maximum HP at high revs. The 310° is still not useable on the road.
--- Quote from: Richard48Y on Thursday,November 24, 2022, 01:18:12 PM ---A bit of information not easily found for TS type heads.
Original thickness/height top to bottom.
Nominal height 93.5mm. (3.681102")
Minimum repair height 93mm. (3.661417")
This can be used to find out if the head has been milled in the past and how much.
Seems milling the head also throws off valve-train geometry.
So head milling is not a good means of raising compression.
--- End quote ---
Do you know, why the minimum repair height is set to 93 mm? My racing head is already well below that and supplies good power. Of course, the combustion chamber is machined in order to fit the high compression pistons. But if the crimp endge in the cylinder head chamber is adjusted to the piston height, it should be no problem to go below 93 mm or is there a danger of cutting into oil or water channels, when doing more plane milling? I have now four cylinder heads and want to modify a second one to full race spec. Maybe even further than the first one, which was a bit more towards safety with compression ratio of 11,5:1.
I love the cylindre head configuration, which is shown attached. It is very high compression, but for 1800 cc. Looks beautiful. Built by JL Engineering. I will take that as a role model for my build.
Richard48Y:
I had a lot of difficulty getting an intelligible response from the French companies regards piston specification. I really never did get a clear answer.
I would have been satisfied with the "160 HP" pistons if I had been able to determine the part number and availability.
The Wossner's I bought from Salv Sacco were still much less expensive than having a custom set made.
I am running them as supplied since I feel the undercut of the dome does not allow removing material from the top.
Since this is to be a "Hot" street driven car I may have to pay for race fuel, or mix in some AV100LL to prevent pinking.
As some on the site have said cutting the head does not alter the components which attach to it but can throw off the geometry of the push-rods/cam timing.
Since you have the adjustable cam wheel you should be able to correct your cam timing.
Cam cores are very difficult to obtain in the US so I have sent mine out to be reworked. One lobe was very porous at the nose.
Once it has been welded I will get it reground.
I am still trying to determine the profile but will probably go with Salv's recommendation.
I am also taking note of the cam-heel side interference issue.
This may not occur with the billet CAT cams.
GavinT:
--- Quote from: Mecky on Tuesday,December 06, 2022, 03:22:11 AM ---
Do you know, why the minimum repair height is set to 93 mm? My racing head is already well below that and supplies good power. Of course, the combustion chamber is machined in order to fit the high compression pistons. But if the crimp endge in the cylinder head chamber is adjusted to the piston height, it should be no problem to go below 93 mm or is there a danger of cutting into oil or water channels, when doing more plane milling? I have now four cylinder heads and want to modify a second one to full race spec. Maybe even further than the first one, which was a bit more towards safety with compression ratio of 11,5:1.
--- End quote ---
Hi Stefan,
The minimum head thickness is set by the factory and is intended as a reference point within a retail Renault service environment. It more relates to customer cars & warranties etc. I expect all manufacturers would have something similar.
Once you go beyond that, understandably, you're on your own as far as the factory is concerned – it's a statement as to the limitation of their liability.
On the other hand, I expect we've all seen some seriously shaved & modified heads. Motor engineers may find this acceptable but with some caveats, conditions and agreement from the customer.
For instance, there's the cam and lifter relationship. Also, it's possible the dizzy base may need to be shimmed as it gets closer to they drive gear. We know that removing material from the combustion chamber comes close to the water jacket - lots of things like this.
I once bought a Renault crossflow F2 engine and the owner said he'd blown it up more times than I'd had hot dinners. I laughed and thought that was a pretty funny anecdote but he wasn't looking to make some sort of warranty claim.
Incidentally, that head measures at 92.8mm.
That JL Engineering head is very pretty.
Interesting . . your Formula Renault Europe pistons are a very similar style to the Renault Sport pistons used in the 1800cc Alpine rally cars (pic below). We often see Gordini style pistons with a different pronounced bulbous hump in the middle.
Do yours also have the "FTV' marking? I'm not familiar with the brand so perhaps it is no more.
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