Tuning the R4

[Niels Svane]

So, after a TON (!) of adaption and modification, the new manifold is now bolted on the car. Then modification of the accelerator mounting plate and carb. mount aaand replacement of the exhaust system with the new, and we'll se how it goes

 

[Jnr-Renospeed]

I've heard new Autobleu manifolds need a bit of 'fettling' to actually fit, looking nice and sporty though !

 

[Niels Svane]

"A bit" ... At least the sidepipe and muffler is just a question of cutting the inner wing and bolting the #%&@ on!
But for now it's the accelerator-lever mounting plate I have to somehow lower 5 cm.

 

[JdeW]

Again I see a 4-1 exhaust manifold, and again why a 4-1?
Normally the 4-1 is for high refs and race performance when calculations, pipe lengths and diameters are properly executed.
For normal road performance I would choose a 4-2-1 system, done my calculations on that kind a system all ready, now it comes to execution.

 

[harbourseal]

Again I see a 4-1 exhaust manifold, and again why a 4-1?
Normally the 4-1 is for high refs and race performance when calculations, pipe lengths and diameters are properly executed.
For normal road performance I would choose a 4-2-1 system, done my calculations on that kind a system all ready, now it comes to execution.

If you can point out some other options Joop please share them with us. There is simply nothing else available off the shelf.

 

[JdeW]

If you can point out some other options Joop please share them with us. There is simply nothing else available off the shelf.

I know the market is scarce for our cars Robert, and what is offered is in my opinion not quit right when it comes to a R4 "tuning" aspect.
The older R4 engines (680 and 800 series) do run at high refs, therefore the 4-1 system is suiteable, but the primairy pipes should be longer and about an inch in diameter before they join the collector.

As for the GTL engines, they run more mid range so a 4-2-1 could be right, but isn't available, so I will build my own. It will be a nice challenge, but a like a DIY challenge as most of us are very capable DIY'rs.
The materials, stainless steel bends and pipes, isn't the problem as we are expanding our brewery for the third time and there are enough leftovers.

For manifold and exhaust calculation I found this site were suitable http://www.mezporting.com/exhaust_length.html
It just uses the very basics of parameters and that's enougn for our small engines. For real tuning one needs a lot more parameters.

Further more the exhaust manifold should be wrapped or applied with a ceramic coat.

 

[harbourseal]

Interesting read Joop. In your comment I find that Niels isn’t so bad off with his Autobleu Manifold. He has a high rev engine.
And I must get another tunable 123 to keep my racecamper at bay. That will be a fun convoy down to Thenay next year. With me running loops around everyone. Because everyone gets left behind. Idd better get the race wheels and TRX tires out then.

 

[Niels Svane]

For now I'll leave the manifold off until I get the possibility to design some custom brackets for the carb in the university workshop.
But now the sidepipe, sports exhaust and connecting pipe is on the car, and after a good clean of the carb, a check up on ignition parts, setting etc. I'll fire him up and put him to good use once again

 

[Niels Svane]

It had some erratic idling/running before all this fiddling about, and it still has it even with a clean carb. All electrical seems fine, so I'm suspecting the fuel pump. Can this "stick"? It sounds/feels like it's running on three cylinders, but it fires on all.
If it might be the pump I'll just replace it tomorrow.

It sounds epic btw

 

[malcolm]

I think the fine details of exhaust manifolding come in to play when you have more horsepower than we do.

Have you checked the compressions @Niels Svane ? It's sometimes been a bad valve when I've had 3 cylinder idling in the past. Ignition leads are a culprit as often as not.

 

[Niels Svane]

Yep, not long ago and it was spot on on all cylinders, and the erratic idling/running (it's also happening in speed) has been on and off.
All exhaust exits get warm and all plugs are firing.

 

[harbourseal]

Hi Niels, Has she been standing stil for a long time?
Then you might have water in your tank. That gives erratic idling and running. Wynns has a doping to take care of condens and water In the fuel tank. I forgot it‘s name.

 

[Niels Svane]

Nope, and it doesn't suit water that well, plus I'm using isopropylebutanol mix.
Now it ran fine again (with the rowdy new exhaust) for about 5 mins. Then it again begun struggling above 1/2 throttle in all gears.
I'm changing the ignition parts stepwise now, but now it nearly didn't start at all, and is running really roughly, so I might not have cleaned the new contact breakers enough.

 

[Jnr-Renospeed]

Might be sludge in the fuel filter, we had that causing irregular poor running in one of our cars, all because of a thin dirty film on the filter paper.

 

[mojobaby]

Maybe its the fuel that you're using. I have no idea what it is, I can't even pronounce it, but it sounds like jet fuel for a high performance race car

 

[André4Renaults]

How old is the condenser? Sometimes it's called a capacitor, but they're the same thing. They do break down internally and cause poor starting & uneven running. There's a way of testing them, using a decent multi-meter, if you want to know how, just ask!

 

[jjad]

Ooh, Andrew, I'd like to know please. I've had one fail on me and assumed it was something else as I'd replaced it only about a year or so before. The old one was probably fine

I've got a multimeter (and an oscilloscope somewhere).

 

[AdamWilkes]

Don't forget the vacuum advance unit screwed to the dizzy - rubber diaphragm that leaks, introducing random air into the carb and not changing timing when needed.

 

[André4Renaults]

If you have a multi-meter that measures resistance (OHMS) then you can do a basic test on a capacitor. Select the highest reading the meter will allow (this is normally 2M) and use the probes to connect one to each side of the capacitor; one is usually the capacitor's boot itself & the other is the metal terminal at the end of the wire. The reading should start at a low level and climb to an infinite resistance after a few seconds. If the meter immediately shows an infinite resistance ("1") then the capacitor is not working. It it's working correctly it should start at "0" and rise up to the "1" reading after a few seconds. Try not to touch any metal parts of the capacitor when carrying out the test, as this can affect the readings (no, really!) Any more questions, just ask!

Another thing you could check (again, your multi-meter might help here) is the distributor's dwell angle. If you can measure it and the number jumps around, it could be caused by wear in the distributor shaft. If the number is a steady reading compare it to the appropriate number it the technical specification for the car, and adjust as necessary. Again, if you're stuck-ask!

 

[jjad]

Thanks Andrew, makes sense