Head porting - how far can you go?

R

Renault17

Active member
Fellow Frogger
Joined
May 11, 2001
Messages
314
Location
New Zealand
Hey,

who knows how far you can port the head on a 1565cc (807-10) motor on a Renault 17?

I don't want to take too much out of the exhaust or inlet ports and hit the water or oil galleries, but want to get somewhere towards round ports I guess. Anyone done this before? The head has already been reco'd , so I don't want to stuff that work up either...

Ben
 
Ben,

I'm not sure how far you can go with porting the Renault head, but keep in mind that any bigger than about 35mm diameter round ports on a 2 litre engine is too big (unless it's an 8000rpm+ race engine), so a 1.6 litre would probably like the ports to be even smaller. If you go too big, the airspeed will slow down too much causing alot of fuel to drop out of the airstream, making the engine inefficient in the bottom half of the rev range. Fuel injected cars can get away with bigger ports (because the fuel isn't injected until late in the airstream), but huge ports are still not a good idea.

The R16 head which I looked at looked like the standard ports were quite adequate sizewise for up to 40mm webers. It could probably benefit from a slight amount of porting, but not too much. But I guess engines over 150hp with 45mm carbs could use larger ports, especially at the outer face of the head. The main thing on most engines is to work on the shape of the port just before the valve and to remove the restrictions around the valve guide. If you want good tips on what port mods work and what doesn't, for engines in general, check out books by David Vizard. He knows his stuff. I have 2 of his books which are particulalry good:
"How to Modify Ford SOHC Engines"
"Performance with Economy"
I think he now has another book which focuses just on heads. He has alot of diagrams of examples of good and bad ports and how to improve them. The surprising thing is that alot of cars have ports which are too large, although this doesn't apply to the 1.6 litre Renault engines. The Renault engines seem to have very well designed ports, from what I've seen. The important thing on engines is to leave a large diameter short side radius in the port (the bottom turn of the port). If you grind much material out of this area it can wreck the flow because it makes the turn too tight.

There are alot of so called expert head modification companies which overdo things as far as porting goes and often make heads worse.

Dave
 
Thanks Dave,

I will check out those books you mentioned. I will just smooth things out I think- I have someone who knows what they are doing watching over me- don't panic. I had planned on 'opening up' the inlets by all of about 1mm all round, and a little bit of 'tidyingup' where there are burrs, bumps etc, nothing too dramatic in case I balls it up really. Cheers Ben

ps saw your pug in the members section- very nice. I forgot that you guys only got the twin headlight jobs in oz- looks b-y good I reckon. Never saw too many of those mags(yours) over here- mine had cheviots fitted as the orginal ones tended to fracture around the holes in the wheels- did you have similar problems?? Did you get the injected ones over there, the v6's you mentioned, are they out of 604's or the 505's. If you hot the injected ones up , can the mechanical fuel injection cope? I'm filing all this info away.....
 
Ben,

Sounds like you've got the right idea with the ports.

Regarding 504s:
Australia did get the Trapezoidal headlights. It wasn't until the end of 1972 or the beginning of 1973 that the round headlights came to Australia. I've replaced the sealed beam units, on my 504, with round lights with removeable 100 watt halogen globes (about $AUS80 worth). The lights are unreal now (although they were always alot better than alot of the latest cars which have really bad headlights), and they are still alot cheaper than the French style Trapezoidal lights.

That photo of my car is taken from the best angle, and takes advantage of the fact that the paint is quite shiny. It actually has quite alot of rough bodywork (pity a previous owner didn't fix it up properly before it was resprayed) and the chassis is slightly bent (from a previous owner), although it doesn't seem to have affected the handling. I didn't pay much for it ($1200 in 1995, although now you can buy a much better one for that price) and the body is ideal for me as I don't have a garage to park it in and I use it for Rallies, etc. When I get a garage I'll get a better body shell and swap everything over. At the moment it's a good distance car (it looks good from a distance).

My car originally had steel wheels. The Cheviots mostly come in two styles. The multi-spoked type which looks nice( but have been known to crack around the spokes) and the type which I have (which doesn't look as good, but they're really tough). I actually have 2 sets of these Cheviots. One set, which my Uncle bought for his 504 in 1979, and another set (the ones now on the car) which I got off a 505, which I bought for the 5 speed box (for $400, my friend payed another $400 dollars and took the engine and some other bits), and apparently they were the last set of those ever made. I've repainted them and they're not too bad.

The injected 504s were sold in Australia from 1971 until June 1976. The Injection system can handle hotting up, up until about 130hp. Beyond that the injection can't provide enough fuel. I've got 2 sets of injection gear (pumps, heads etc), but since they don't make spares for all the parts anymore and there are a few things which can go wrong, I don't feel like using the injection on an everyday road car. The injection is usually quite reliable, but once it's been fiddled around with, abused or worn it can give annoying troubles. I have heard of a modified 504 using the injection manifolding with an after market EFI system. I think that is probably the best way to go, to get good power figures out of these engines. It would be easy to mount a larger throttle body on the inlet manifold also, if EFI was used. I don't like the short side radius on the injection head ports. It is a much tighter curve than the carb head ports. You can modify the early carb heads to give them 4 normal ports (usually by welding or epoxy filler), which I think would flow better than the injection head.

Most of the 504 V6s which I've seen use the 604 2.7 litre engine and 604 engine mountings and gearbox (manual gearboxes were never oficially sold in 604s in Australia, so it is hard to find the correct V6 bell housing). If you look in the "past events" section, the white 504 V6 of Tom Subi, uses a 2.85 litre V6 from a Volvo. It is probably the nicest V6 504 sedan in Australia (if not the Universe). The 505 V6 was never sold in Australia.

If you want any more info on hot 504s in Australia, just ask. I think there are more hot 504s in Australia, than any other country. France or Argentina may have more, but if the internet is any indication, they don't.

What alloy wheels did you have which cracked. Were they Dunlops?

Regards,
Dave
 
Ben,

What brand are those alloy wheels on your R17? They look great! Are they 3 stud or did you have to convert the car to R18/Fuego 4 stud hubs, etc?

Dave
 
Ben,

I've just remembered something about the 504 Kugelfischer Injection. It uses a camshaft inside the injection pump to control the fuel injection. Some people used to grind a special camshaft for the pump to allow it to deliver more fuel. I've heard they worked quite well. I haven't heard of anyone doing this recently. They used to charge around $500, 20 years ago, for these cams. Nowadays, I think using an aftermarket EFI computer like a Haltech, Microtech or DDS would be much better value for money.

Dave
 
Dave,

thanks for the info re: the injected pug cam grind, there is a mint one of these locally, but it's an auto.... can't help but think of the possibilities

As for the mags that cracked they were the cheviots, the minilite - std Ti mags that they came with were even worse for cracking so I am told.

Probably didn't help things with the way I treated the car though- gave it a fairly hard time- blew the diff, ran the bearings etc etc -as you do in a first car (doesn't everyone?)

Anyway the wheels on my 17 are brand spankers- still with the 3 stud too, the beauty of which is that no bugger with a toyota will EVER try to steal them!!

My brother owns a tyre shop and got the wheels brought in as blanks and drilled to suit the stud pattern of the 17- easy as. I gather that he arranged for the correct offset then it was simply a matter of getting them drilled. The wheels I have on mine are 15*6" superlites from Performance Wheels, you should be able to get them in OZ too.

Cheers Ben
 
Ben,

I didn't know you could order the wheels as blanks. I think those wheels would look great on a 504 or for that matter, any car.
The three studs are a great anti theft feature. What are the wheels worth as blanks?

I've heard of people stealing 505 15" alloys to fit to Pre-Liberty Subarus, which are the only other cars which use the same stud pattern as 504s/505s/604s. I think this is a rare ocurrence though. No one wants 14" wheels these days, so I think my wheels are reasonably safe.

Dave
 
Hi guys, Ben thats very interesting about buying blank wheels, I've heard of that but everytime I've asked I keep getting told no way, maybe I'm asking the wrong people. We do 4 stud conversions at work, we have all the patterns to do it properly so that gives people a huge choice of wheel.

David.
 
Guys,

maybe it's a case of the wheel retailers not wanting to go to the trouble of getting blanks drilled to suit, I'd keep trying tho' as it obviously can be done.

On the note about Subarus David, over here with the multitude of imports we get,(dig dig, even bringing in stacks of Euro cars from Japan now too) the subaru leones had a minilite type of mag wheel- 14", if this was the right offset (I have no idea) then that could solve your problem too, no doubt a lot less than getting brand new wheels.

Just a thought,

Ben
 
Hi Renault 17
Where in NZ are you
I am in Auckland. I have just sold my last 17 and I have a whole lot of parts in my shed. Do you want them?
I am also interested in your discussion about wheels. I am trying to get hold of some alloy wheels to suit R8/R10 but without much luck. Finding the right offset seems to be the main problem.

Ross
 
<font face="Verdana, Arial" size="2">Originally posted by Ross:
Hi Renault 17
Where in NZ are you
I am in Auckland. I have just sold my last 17 and I have a whole lot of parts in my shed. Do you want them?
I am also interested in your discussion about wheels. I am trying to get hold of some alloy wheels to suit R8/R10 but without much luck. Finding the right offset seems to be the main problem.

Ross
Click to expand...
Hi Ross,

I've e-mailed you as well, but yes I could be interested in some 17 parts, just what do you have available? If you give me a ring I can put you in contact with my brother re: alloy wheels for your R8/10- he owns a tyre shop. I live in Palmerston North, my ph no. is 06 356 8043, give me a ring and we can have a yarn about things.

Cheers Ben
 
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