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Extracting performance out of 1108cc

RichardIRL

Enthusiast
Messages
329
Location
London
#1
Does anybody know a simple and cheap way of extracting slightly more power out of the 1108cc engine in the GTL. I know the same engine gives more power in the Renault 5.

Also does anybody know about switching gearboxes between R5 and R4
 
Messages
1,406
#2
Nice easy question Richard, as I've done both to my car.

Firstly, the power issue. Get a 1108 basic 5TL with the solex 32 carb. Swap carb, manifold, air filter, water pump and carb heater hoses and rocker cover. Fit these to your 4GTL and slightly modify your choke and throttle cables. Remove the 5 throttle return spring and make up a simple bracket and fit to a manifold nut using a weaker spring for the throttle return. Do the basic timing and adjust the mixture and take it out for a spin. If you get pinking, retard the distributor to zero degrees. If it still does it, try a 117.5 or 118 main jet in the carb and then adjust the timing to the pinking stage, then back off a little. You will also need to rig up a hot air intake for the winter. I grafted a Mini bi-metal air intake unit onto the filter housing with an intake pipe drawing hot air from the front exhaust pipe.

Make sure your car is properly converted to unleaded or you are using an additive.

From the same 5TL, remove the gearbox, remove the aluminium housing and the top cover/bolts and bin these. Remove the diff as per Haynes manual. Remove the spigot shaft (the 5 is about an inch longer than the 4GTL). Now fit the 4 spigot shaft, the diff and the aluminum housing from the 4. It's good practice to replace the spigot shaft oil seal, the half shaft oil seals and the 'o' rings in the diff bearing retainers at the same time. Then carefully fit the top plate/gear lever assembly (including bolts) from the 4 onto the box. Don't bin the 5 spigot shaft as this is useful for clutch plate aligning.

That's it :D

The carb conversion took me around 3 hours plus getting the settings right. The gearbox took me 2 hours to convert.

With my 4 I also fitted 155/70x13 tyres. Better round corners and cope well with the extra power.

Steve
 

malcolm

& Clementine the Cat
Staff member
Messages
4,118
Location
Bedford UK
#3
That's good information. I've been thinking of the same sort of modification. Renault strangled the 4's engine, and I had been wondering how much was down to the carb and how much the camshaft. Steve's experience suggests that the carb is by far the most important part.

Mk 1 Renault 5 spares are scarce these days, and I'd been thinking it would be a shame to break a whole car just for the carburettor. It's occurred to me it should be possible to fit the Renault 4 carb to the 5 and sell it on as a complete car.

Mk 2 (transverse engined) Renault 5s can still be found in scrapyards. It would be a much more difficult job to fit the inlet manifold from that car as the inlet and exhaust manifolds are made in one casting. Probably not impossible to cut the manifolds apart. If I give it a try I'll report back with details.

Steve, you've got a Mk2 Renault 5 - does the waterpump from that car look like it will fit the Renault 4? Or would I still need to look for the Mk1 waterpump?
 
Messages
1,406
#4
It's not worth messing around with the cam unless you've got the engine out and stripped. In that case you could have it re-profiled, but quite honestly, the lighter weight of the 4 compared to the 5 is more of a bonus than a hotter cam - ie the engine has less weight to pull.

Again, if the engine was out anyway and you just happened to have a 1300 Mk1 5 sitting there, pop that engine in with all the ancilliaries and mate it up with the 4 gearbox.

The 28IF downdraught carb originally fitted to the 4GTL will go straight onto the 5TL with it's manifold. You would also need to retro fit the 4's rocker cover and water pump etc. A problem would be encountered fitting the 4's air filter unit as the bonnet line on the 5 is lower than the 4. Again, cables would need to be modified.

All our (and the Mk2 5's) manifolds are in one casting anyway, so no need to waste money on hacksaw blades. Also the Mk2 5's exhaust outlet is in a different postion.

The Mk2 5 waterpump is completely different to the Mk1 5 and could not be used.

Following an interesting discussion the other day, it may be possible to increase the 1108's capacity to 1400cc by using the liner/piston/conrod assembly from the Mk2 5GTL in the 1108 block. I would need to do some further research into this.

Saying that, the carb mod I did on my 4 pushed the top speed up to 90mph with healthy acceleration to match, so before considering spending lots of money in making your 4 the fastest one on the road, ask yourselves whether it's really worth it. Sounds like fun though :D

Steve
 

RichardIRL

Enthusiast
Messages
329
Location
London
#5
I'm considering replacing the whole engine on my car so I wonder how much bother it would take just to throw the whole engine from the 5TL into the 4.

Maybe the 1397cc one instead of the 1108cc.
 

Anonymous

New Member
Messages
4
#6
If you're doing an engine swap from a 5 to a 4, you'll need to use the 4's engine mountings and brackets. Whether you're removing a 5 or a 4 engine, it's a five hour job. Remove engine and gearbox together as a unit.

Steve
 

malcolm

& Clementine the Cat
Staff member
Messages
4,118
Location
Bedford UK
#7
Out of interest - does anyone have a manual for the Renault 5 MK1? If so what cam timing (valve opening/closing degrees) does that car have? It would be interesting to compare that with the R4.

:D
 
Messages
1,406
#8
I finally managed to find my R4 and R5 manuals and the camshafts and cam timing are exactly the same for the 1108 engines as fitted in both cars. I.e. the engines are identical so the extra power is obtained purely by fitting the R5 carb set up to the R4GTL.

Steve
 

Mr Jelly

Enthusiast
Messages
57
#9
If you can get hold of the 1397cc engine then it's well worth it, however, it is older and was only fitted to the 5 TS until (about) 1979. After that it was a 14xx cc engine which whilst ok wasn't quite as quick and on GTL / Automatic R5's was fairly strangled in the name of economy. The 5 TX was much better with different carbs so would be good.

Don't know about on a 4, but on a R5 it's easier to split the engine and box to get them out but it's a fairly straight forward mornings work.

May I, at this point add that if anyone is interested, I have a engine and 'box from a 5 TX sat here complete with ECU. Was running fine when it came out of a very very rotten 65k 5TX that I scrapped last November. Should still be Ok and about £75 (ono) would buy the lot........ :wink:
 

malcolm

& Clementine the Cat
Staff member
Messages
4,118
Location
Bedford UK
#10
Thanks for digging out the cam timing Steve. It's shocking that they would strangle the R4 on the carb alone due to the efficiency issues. I guess that's why the 1.1 5s were just as economical as the 4s.

I've done my customary minimal research into the 5TX. Seems it's a late Mk1 1.4 which would make it compatable with the R4. Does it have the 5 speed gearbox? If so you might have a sale there. I've been considering tinkering with one of those. But what is it doing with an ECU? Makes me think I need to do more research.

:clementi:
 

Mr Jelly

Enthusiast
Messages
57
#11
Yes the R5 TX was a late, high spec R5. It's a 5 speed and was set up more for power than economy. The 'ECU' was just very basic and (if I remember rightly) was there becuase the car had electronic ignition. I would imagine that in a R4 would make it very interesting, probably better than those R4's fitted with Gordini / Turbo engines as it is considerably lighter.

Have a look at http://www.r5gordini.co.uk/site/My_Cars/Renault_5_TX for more info - this is a very good site by a friend of mine who knows a thing or two about R5's.
 

malcolm

& Clementine the Cat
Staff member
Messages
4,118
Location
Bedford UK
#12
I'll definitely have the engine and box off you then. It might well find itself into a Renault 4 if I can figure out the gearchange conversion. I'll contact you off-line to make arrangements.

I occasionally flip through Andrew's Renault 5 site. Actually that's where my Renault 5 research is done. He helped me out by E-mail when I first set up this site. Will have to send him my picture of the Renault 5 with a boot, as I don't see any on his site.

 

Mr Jelly

Enthusiast
Messages
57
#13
Renault 7's (5's with a boot) are rather cool. I believe there are only three in this country as they were only built for the Spanish market...

Sent you a PM with my mobile number, give me a ring about the engine when you get chance..
 
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