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RICHARD MANN'S CROSS FLOW RENAULT ENGINES

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Lotus 47:
I'm not sure where to start!

Maybe from the beginning!

I purchased my ratty 1970 S2 Europa in Sept 1987. 7004100119Q - an Australian delivered car that was originally fitted with a 1470cc 697-04 engine. When I got the car it was fitted with a standard 1565cc 807-01 R16TS engine. These engines were plentiful in the 1970's, 80's & 90's because Renault had an assembly plant in my home town of Melbourne.

The installation in my car used a stock R16TS cast iron exhaust manifold and twin throat down draught Weber. The chassis top flange was bent out of the way to clear the exhaust manifold, and a very crude air cleaner sat atop the Weber

On paper there seems little point in swapping the engines. The Europa engine is 82hp, the R16TS is 83hp. However the 16TS engine is the basis of the A110 1600S engine (138hp) that was a huge success in rallying, and also power the R17TS and R12 Gordini engines that were rated at 125hp.

All this horsepower came from a fabulous  cross flow head reputedly designed by Monsieur Amedee Gordini. The bottom end was unburstable, and the lightweight alloy block is a lesson in simplicity.

I've built a few Alfa 105 engines over the years and while their heads are fab (if you can get them off!), the bottom ends and front timing chain area is overly complex and an absolute prick to work on when it is installed in the car. Removing the water pump is a classic example. And don't get me started on removing the engine. Almost as frustrating as an Elan!

So my starting point was a standard R16TS engine.

While I talk in horsepower I measure in millimeters. After all it is a French engine, and in Australia we converted to the metric system in 1974

COMPONENT                           697-04          807-01

Cylinder head                   Non Cross-flow   Cross-flow
Power                                       82hp           83hp
Capacity                                   1470cc       1565cc
Compression ratio                    10.25          8.6
Bore                                         76mm         77mm       
Stroke                                      84mm         84mm
Bore spacing                            89mm         89mm
Bore sleeve step size (early)    82mm          82.5mm
Bore sleeve step size (late)      82.5mm      82.5mm
Inlet valve size                         37.5            40mm
Exhaust vlave size                   31                35mm
Piston top                                raised          flat - notch for inlet valve
Gudgeon pin size                     20mm         20mm
Sump                                      deep            deep


My first iteration of this engine took the normal path - Carbs for breathing, exhaust for breathing, camshaft for breathing
If an R17TS can get 125hp, so can I!

Lotus 47:
BASIC CROSS FLOW UPGRADE.

The first engine I built with a decent amount of poke used the standard R16TS that was fitted to my car.

EXHAUST
I built a crude set of tubular headers, with unmatched lengths. primary pipes were 38mm diameter (OK actually 1.5"), with 1.6mm (1/16th") wall thickness. I bought 90 degree mandrel bends and gas welded them. I hand cut a 6mm steel plate to bolt to the head. Hand cutting is a crap job. The ports are oval AND angled, so hand cutting really was the only alternative I had back around 1990.

I bought a muffler (silencer) with 2 inlets and a single outlet, so my 4 tubular "headers" merged into 2, then went straight into the muffler. There is zero room for much else in a straight thru  system.

INTAKE
Twin 45DCOE Webers on R12 Gordini replica inlet manifolds. These manifolds were produced locally for some years, but are no longer available. Steve Veris can help out. Or Mecaparts, for which you will pay Mega dollars - photo below.

The Webers had 36mm chokes. No idea what jets were fitted! The Webers were mounted to the rigid R12 manifolds with a  rubber seal in between and cushion  absorbers under the heads of the nuts securing the carbs to the manifold. I have run these type of rubber seals for years without issues - see photo below


I fitted FOAM intake socks for a short time, until the car backfired one cold morning and set the foam on fire. I was at a service station about to fill up with petrol and I got out to see flames licking up thru the holes in the engine lid. I ran inside the store (it was a 7/11) but they didn't have an extinguisher! I ran out, throwing a couple of buckets of water on the car and extinguished the flames, I will NEVER use foam as a filter again. After that experience I set about fitting a nice steel canister around the Weber trumpets, and fitted a remote air filter. I used an R16TS filter housing and cut it down. This proved effect and during dyno testing we removed the canister lid and ran straight trumpets. Not power change occurred, which showed the air filter and trunking design was effective and did not restrict air flow - very important!

COMPRESSION
Nothing changed here. I used the standard flat top R16TS psitons with a lightly skimmed head, so it was probably under 9:1 compression ratio

HEAD
On the advice of those that know better, I sent my head to a specialist in Sydney - Colliers. He fitted large 42mm inlet valves, stiffer outer valve springs, and ported the head slightly.

The 42mm valves were fitted to the R17TS and R12 Gordini engines, plus the A110 1600S. They were available from my local Renault specialist back then. The head also had a little bit of work around the inlet valve to improve gas flow.

CAMSHAFT
The R16TS figures I don't have in front of me but they are far from "racy". Lotus had learned a bit from the Twin Cam and the Europas 35/65/65/35 cam timing gave a healthy boost in power with 280 degrees duration. I don't know what lift they used.
Knowing nothing about what alternatives to try, I asked around and the common grind seemed to be an A6 Cosworth profile used in Ford based performance engines. This was something like 46/78/78/46 with 304 degrees duration and about 10mm (0.4") lift. I was warned it would be a bit peaky for road use, but would work better in the Renault engine because it was a long stroke engine.

RESULT
It worked!
The carby jetting was far from perfect, but as a young-ish lad it provided all the go I needed for a traffic light racer. it was also effective on hill climbs and circuit lap/dash events.
I clocked 14.9 seconds on the 1/4 mile.

One club night we put my car on a dyno and it produced 75kW (100hp) at the rear wheels. And we limited engine rpm to 6000. It pulled sweetly to 8000, so there was more in it. Taking into account driveline losses I figured my engine easily met my 125hp target. the dyno man stated it was the best 1600 he'd ever tested! I put in all down to the head design. It really is VERY good

The major costs were the head mods, and the twin 45DCOE. No pistons, rods or other major mechanical changes. The cam regrind was about A$80. The distributor was modified by Colliers as well. They restricted the advance and fitted a different spring to one of the counter balance weights, plus fitted "heavy duty" points. I still run the same distributor today after 25 years! As the engine was sourced in Australia, it ran locally produced Bosch electrics - dizzy and starter.

More to come and of course some photos to keep you all happy
 

Lotus 47:
RENAULT ENGINE BLOCKS

Today's lesson is all about the Renault blocks and what you might find.

The an important feature is the engine mounts. Below is a bunch of pictures showing the engine mounting holes you need, plus a version you might want to avoid.

The block casting will suit a cross flow AND non-cross flow head.

All these blocks below use the 84mm stroke crank.

These blocks fall into two distinct categories

The Type 801 and 821 engines use 77mm bore liners with a stepped section at the bottom on the liners that measures 82.5mm. These seat on a square step, and use paper style shims/seals between the liner and the block. Capacity 1565cc

The Type 841 and 843 engines use 79mm bore liners with a stepped section at the bottom on the liners that measures 84mm (I need to check that dimension!).  These seat on a square step WITH A CHAMFER, and use a rubber O-ring seal between the liner and the block. 1647cc

The Type 821 comes from the later Federal S2 Europas. It has a non cross-flow head
The Type 841 comes from the Renault 18 sedan. It has a non cross-flow head
The Type 807 comes from the Renault 16TS sedan and R15/17 coupe. It has a cross-flow head
The Type 843 comes from the Renault 16TX sedan and maybe the Fuego and R20. It has a cross-flow head
 
I think the 697-04 block, which has 76mm bores, will accept the slightly larger 77mm bores. The crank is 81mm stroke, v's 84mm for the other engines.  I am 99% sure you can fit a 84mm stroke crank in the 697-04 block without any mods to the  block.

If you have a block that has Europa compatible set of engine mounts, then you are on your way to start building an engine any where from 80hp to 160hp.

The 84mm stroke cranks are good for revving, and generally have very hard journals that may not have worn and may not need to be re-ground.

The case or cover that goes on the front of the engine (in a Europa) has two basic variants. With and without a hole for a front crankshaft pulley.

The front cover hole pattern varied but basically the covers can be interchangeable with any block (some had dowels replacing 2 of the bolts)

The sump bolt pattern never changed.

The cranks fit any block.

One flywheel fits all.

The flywheel and crank have an offset hole pattern, so the flywheel can only be bolted-on in one specific position. It has a timing mark machined into it.

The timing chain never changed and I think the timing chain tensioner never changed.

This is one tough and light bottom end, with a huge amount of commonality. This commonality leads to relatively inexpensive parts like main bearing shells and conrod big end shells.

I gather cross flow Renault engines are relatively rare in the US, so if you find one, carefully inspect the block for the mounting points, but don't worry if they are different! If they are wrong, you can always substitute your 697-04 block or 821-30 block.

If you have a decent machinist at you disposal, you can modify the block to accept the larger liners with 79mm bores.

Too easy mate!

old racer:
Richard, thanks for putting this up, you are a fountain of knowledge!

I'm in Sydney and have chassis 7005130185Q, 66 cars later than yours. Also Australian delivered and still with original 1470cc engine. Over the years I have collected a couple of R18 engines and 5 speed boxes and three R16TS motors with the intention of building a cross flow engine using Mecaparts high compression pistons. From your advice maybe these rather expensive pistons are not necessary. I guess any increased horsepower will also require drive shaft mods.

I have held off doing any modifications as the car is highly original and only used to buy the paper on a Sunday morning, but should that 1470cc engine spit the dummy I'll be following your instructions.

Cheers

John

Lotus 47:
Hi John,

An Australian Europa with the original 1470cc engine is a rare beast indeed! If the car hasn't been modified, I'd advise to keep it that way. However, I like to think all the mods I have done over the years are reversible, so if you attack it with the right mind set - modify away!

Fitting a 5 speed is a big job. Can you justify it if you are simply using the car to buy the Sunday paper and smash out a few Sudoku and the daily cross word?

If you want to build a 130hp+ engine, then special pistons will be required to raise the compression. There are many ways to approach this, and I'll cover some of them in one of my lessons.

I'm only a phone call away if you would like to discuss a modification in more detail 0419 565 959

Cheers!!

Richard Mann
26/4101
460047
47-GT-3
7004100119Q
A110 1300VC15899

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