S16 head mods

P

Phasis

Guest
Ok, so im just throwing around potential mods willy nilly in this forum, but this one seems like it might actually be worth it.

After reading the whole of that Puma Racing tech site, and emailing them, I think the $800 odd that I was looking at putting into brakes would be better spent on performance.

I rang Advance Performance Center (thanks jr) who put me onto a bloke name John Hill I think. He specialises in engine engineering, much like Puma Racing. He has quoted me $770 for full porting and flow bench work which will give about 20-25% more power right away. This will take my est. 164hp up to over 200hp, the magic figure of 100hp/litre I am after.

John has done the head mods on the 405Mi16 Targa Tazmania car which was at UQ for the Grand Display, so at least he has seen one head like mine.

Furthermore, the 16v engine has large valve seats that will take 2mm larger valves, seeing a 10% increase in size and arounf 8% increase in power, but this would be about $600....diminishing returns.

Anyway, has anyone had any experience with head porting and flowing, either doing it or having it done (engine head that is
smile.gif
)?

Are these figures realistic and what downsides are there. I REALLY dont want to loose the low rev tactility of the as I rarely rev over 6000rpm. I am more interested in a better power curve rather than pure HP, although 200hp would be sweet.

Ta Much

Phasis

[This message has been edited by Phasis (edited 20 August 2001).]
 

peugeot

New member
Thanks Brad,

I have a quote here for you for brake upgrades and you are going to do performance?
I can get one of those for you too if you want?

Thanks Nick

------------------
Pug Action - French Styling in Australia.
http://drive.to/pugaction

President of Peugeot GTi Autosport Club of Australia.
http://www.peugeot-gti.com
 

davemcbean

Guru
1000+ Posts
Phasis,

Every naturally aspirated engine I've read about that has 100hp/litre, produces that power at over 6000rpm. If you rarely rev the engine over 6000rpm, then the 200hp conversion won't be much use to you. Those engines are strong, so you shouldn't be scared to rev them to 7000rpm often, because it can't possibly hurt them. It's usually only really old fashioned engines (mostly older than 40 years) which get damaged below 7000rpm. Almost all five main bearing overhead cam engines can rev beyond 7000rpm without damage, but usually the camshafts and valve sizes aren't optimised for efficiency at those revs, so there is no point in reving them that high.

Dave
 
P

Phasis

Guest
The 200hp figure is just a realistic goal. As I said in the first post, and as the Head mod guy said, they dont go for a HP figure, they go for greater acceleration. So i guess puttinjg a figure on it is not quite right. What I also might do is get the flywheel lightened, as in 1st gear, where I feel my car doesnt pull as hard as it should, taking 2kg off the outside of the fly wheel is equivelent to taking off about 100-150kg of body weight.
 

davemcbean

Guru
1000+ Posts
Phasis,

Yeah, I had approx 2kg taken off the outside of my 504 flywheel. It only cost $40, so it was worth it. I did a few other mods to the engine at the same time, so I'm not sure just how much the flywheel contributed to the better performance, but it certainly hasn't caused any bad side effects. It still idled well and the smoothness of the engine didn't seem to be affected at all. Actually it's one of the smoothest 504 engines I've driven, even though I never had the flywheel balanced. Having said that, though, it is a good idea to have them balanced anyway.

Dave
 

Murat

New member
Phasis,

Sorry to say but if 200hp was available under 6000rpm without loss of tractability peugeot's mechanical engineers would have designed such an engine combination.
To achieve 200hp you will need to rev past 7000rpm maybe 7500-7800.
Twin cam engines were designed to be reved thats what it was all about smaller lighter valvetrain.
In fact you would be better off with say an 8v engine if you r not going to rev past 6000rpm.
But it's your car you can do what you want just stating some facts.


Murat
 

Andreas

New member
not wanting to be sceptical but 25% from portiung!?!?
unless he's talking abotu major work that'll make the car undrivable i doubt it very much.
dont take it passed 6000rpm much?
you havent lived haha
 

Stuey

Member
1000+ Posts
Yeah, I agree. Even on really old fashioned engines (which generally benefit more from porting) I reckon you'd be struggling to get that benefit, at least without ruining your lower speed driveability.

I used to be into Mini Coopers (and had a Cooper S). I modded a Mini 998 motor in a second car, and followed David Vizard's methods in one of his books. However, I was a bit ambitious (I was only 18) and went for the 'full race' spec, with huge ports, valves etc. etc. and high compression.

Well that thing used to rev out like crazy, and topped over 170 k's (which was pretty fast for a Mini 998). Unfortunately, it was as gutless as hell down low...

My advice would be to make sure the head guy seems to want to give you exactly what you want (eg. driveability + some more power) and doesn't just bandy about big numbers).

Cheers!

Stuey
 
P

Phasis

Guest
Again, these were just round-a-bout figures. I wouldn't expect the 20% which he stated, hower even if 10-15% was achived, for $770 its alot cheaper then some other mods which get similar results. In all, again, I am after acceleration, and as the ECU cuts out the engine at 7000rpm, the tunning would have to be done to get the most out of the engine with the standard revs.

BTW...in saying i dont take it over 6000rpm, thats only in normal driving, if i want a blast, 6900rpm is the change up point...I like to blast.
 
P

Phasis

Guest
davemcbean -
How did it only cost $40 to machine the fly wheel? Did you have the engine and fly wheel out already?

What would be the cost to do it with the engine in place?

Murat -
The work involved (about 20 hours) to port the head to the quality that I am talking about would not be possible on a production line. There would need to be lesser tolerances to reduce risk of manufacture errors, and the shape and size of the ports would be limited by the machines beign used, costs and time.

Even if 40 hours manual porting could bring about 200hp without major loss of low end tractablity, no car company would be able to justify spending this time and money on an engine when I am sure the whole car could be built on the production line in less time.

In terms of loss of low end tractability, from what I have read on the subject, by simply porting and flowing the head, therefore decreasing restrictions and increasing the ammount of air able to flow into each cylinder, low end power won't decrease because no alterations are being made to the timing, valve lift or duration. The cylinders will just be able to fill with oxygen more efficiently at high revs.

All good arguments though. It has made me think about the questions I need to ask before doing this mod.

[This message has been edited by Phasis (edited 23 August 2001).]
 

Chipper

New member
Phasis,

From what I understand (admittedly, not a great deal) to much porting can drop the port airspeed and hurt your lower rpm power without increasing the total airflow at all.

Larger port = lower air velocity ??? (i am sure someone can correct me here)

I read this on a site, and it was for the 8V motor, may be different for the 16V.

Have asquiz @:

http://www.motorsport-developments.co.uk/peugeot_205_8v.htm

I believe they have info on the 16V there as well.

Just bung a supercharger on there mate, and hang on !!!

Chipper
smile.gif


[This message has been edited by Chipper (edited 23 August 2001).]
 

davemcbean

Guru
1000+ Posts
Phasis,

What Chipper said is correct. If the ports are too big it lowers the airspeed and can negate any useful inertial ram filling of the cylinders.

I think you will find that the Pug 16 valve heads are very well designed (I think they were designed for motorsport) and the port sizes would be well matched to the standard camshaft timing. If you had a wilder cam and longer inlet runners, then a slight enlargement may be of benefit, otherwise I wouldn't do it. You will benefit, though, from cleaning up the port within 10mm of the valve seat insert, and removing any excess alloy material around the valve guides. You will need to have the guides pressed out to do this properly. If the guides are not already tapered at their ends, its useful to have it done while they are out. Bigger valves should also be beneficial, providing the internal diameter of the seat insert is bored out, if not, what's the point in fitting large valves?

Regarding my flywheel, yeah, the engine and flywheel were sitting out in the open in my fathers garage at the time. I took the flywheel to a local machine shop in the morning, told them to "remove all this material in a nice smooth taper from here to here" and picked it up in the afternoon. I weighed it before and after. Before, it was approximately 10kg, after it was approx 8kg.
I guess if you paid someone to remove your flywheel from the car, the labour costs would be similar to replacing the clutch.

Regards,
Dave
 
P

Phasis

Guest
Dave, Smoothing and cleaning up the ports was really all I ever thought weas going to occur, + a little enlarging as a result of this. However, what increases would you see reasonable to expect when only doing the small port "clean-up" you were talking about, and not the valves?

Would it be better to spend the $800-900 on the bigger valves (which at $66 each custom made makes over $500 worth)and perhaps a different cam, like a fast road cam? However wouldn't this degrade bottom end more than porting?

Brad
 

davemcbean

Guru
1000+ Posts
Brad,

I'm not an expert, but either enlarging the ports or using cams with more overlap, will reduce the bottom end. By how much depends upon how big you make the ports or how wild you go with the cam.

Larger valves have the same effect as increasing the valve lift, which should not hurt bottom end torque (if it is done correctly).

Just cleaning the ports up, as you say, shouldn't enlargen them significantly, if it's done right. I think that is worthwhile providing the person you pay to do it knows what they're doing. The most important part of the port is the area within 10mm of the valve seat insert where the transition between the curve of the port meets the insert. Smoothing this small area up and cleaning up the top of the port where it meets the valve guide is beneficial. These are the areas where there is always room for improvement, because it requires hand finishing which manufacturers can't afford during production. Many people get carried away with the porting and make the short side radius curve too tight (the inner radius of the port as it sweeps onto the back of the valve).

I can't tell you which of either the big valves or cleaning up the ports will be more beneficial. That judgement requires experience with those particular engines. I would guess though, that these two together (without a diffent cam) would give you a very flexible engine with a very noticeable improvement in performance.

If you want to get good advice on modifying engines in anyway, you can't go past the books written by David Vizard. They are available through amazon.

Regards,
Dave
 

davemcbean

Guru
1000+ Posts
Brad,

Just to clarify something, when really large inlet valves are fitted, it can reduce bottom end torque. On engines where the valves are small to begin with, a slight increase often has no down side. 16 valve engines have smaller valves than 8 valve engines (because there's more of them). From what I've read, putting larger valves in the Mi16/S16 engine has no ill effects. The best idea is to talk to somebody with experience in modifying these engines.

Regards,
Dave
 
Top