Cam Pulleys

[Ren 0]

Having just changed the cambelt on my 1.9 Mi16 I noticed that the cam pulleys were no. 4 on the inlet and no.2 on the exhaust. I remember reading on here that different pulleys can be used for more power or torque but don't really understand that much about engines to be able to grasp how.

 

Anyway I found this topic http://forum.205gtidrivers.com/index.php?s...ey%202&st=0 and specifically this post

 

if anyone is still interested, here is the definitive finding on the #4 cam pulley:

 

1) it is fitted on late-ish BX16v with late D6C non-CAT engines (CR 10.4 : 1)

 

2) it is used ONLY on the Inlet cam

 

3) the Exhaust cams on these late 160 HP non-CAT engines use a #2 pulley

 

4) the Exhaust cams on ALL BX 16v engines are DIFFERENT themselves

(more duration)

 

5) the #4 pulley has a cca. 139 deg. "separation", which makes it WAY more retarded than #3 and #2. It is used for better top-end and better cylinder filling at high RPM. I guess that is one of the explanations why these late 160 HP BX16v are so unbelievably fast as a top-speed performance...

 

It can also make a dramatic improvement if used as an Exhaust pulley on, say, a hillclimb or rally engine, where a healthy mid-range is needed.

 

All I really want to know is if a 4 inlet and a 2 exhaust is good for a standard road car?

 

On a side note it says that these were out of a bx but my engine definitely came from a 405, although it was an ex unmarked cop car so do you think they would have put the no. 4 on?

 

Any help much appreciated.

 

Cheers, Ren.

[Anthony 1,000]

#4 inlet gives a better spread of power at the expense of a small loss at top end, or atleast that's how it subjectively feels from driving the same engine on a #2 and #4 inlet pulley.

 

Certainly based on that car, I'd go with a #4 inlet on a road-car that will inevitably spend alot of its life in the midrange.

[petert 550]

5) the #4 pulley has a cca. 139 deg. "separation", which makes it WAY more retarded than #3 and #2.

 

What you've said is mostly correct, except the lift at TDC results for the various pulleys on a standard cam go like this:

 

#2 - 0.032"

#3 - 0.045"

#4 - 0.060"

 

Therefore, a #4 must be more advanced than the other two and thus perfect for a road car.

Edited February 7, 2007 by petert

[Rik 0]

Could a #4 pulley be used on the exhaust cam?

 

I believe i must have one of these engines then! because i had a #2 inlet and #4 outlet on my engine when i took it apart!

 

Rik

[taylorspug 7]

Engines with a number 2 and 4 pulley would have come with the 2 on the inlet and the 4 on the exhaust as standard from the manufacturer (im guessing your engine is from a Citroen?).

 

Certainly the number 4 on the inlet gives impressive mid range torque, but after trying it for a bit i swapped back to 2 inlet 4 exhaust, as i felt it was robbing the top end a bit too much for my liking. Seeing as my motor spends 80% of its time at 4k plus (bloody 1.6 box!), and even more when its getting thrashed, the lack of low down torque wasnt an issue for me personally.

[petert 550]

Engines with a number 2 and 4 pulley would have come with the 2 on the inlet and the 4 on the exhaust as standard from the manufacturer (im guessing your engine is from a Citroen?).

 

I've seen a Pug. engine with #4 on the inlet. It was a late model 3 row ECU D6C.

[taylorspug 7]

Mines a late 3 row too. All the ones ive seen here have either been 2 inlet 2 exhaust, or 2 inlet 4 exhaust. Considering most people have no clue about the pulley differences i suppose its not inconcieveable numpty mechanics have taken them off in the past (maybe to do cam oil seals etc), and then put them back on wrong. So who knows what weird and wonderful combinations some people have...

 

Oh well, as long as my engine isnt down on power because of it!

[Rik 0]

Well mine is a D6C but cant remember if the engine was a Citroen or a Pug when i first bought it!

 

And the wiring loom i have is probably from a completely different engine!

 

It might be worth trying the #4 pulley on the exhaust if it has more lift, what difference could it make?

 

Rik

[Dazza 4]

How can you tell these numbered pully's ,do they actually have the numbers stamped into them ? ive 3x MI16 engines and i cant see any numbers on the wheels ....?

[Ren 0]

Yes, the numbers are stamped on the pulleys.

 

Just to clarify the above data is taken from the post mentioned not from myself.

 

So bearing in mind that my engine was from an unmarked police car do you think the pulleys were put as 4 inlet and 2 exhaust on purpose for this reason or that the mechanics put them back on wrong?

 

Ren

[Dazza 4]

Are they i must need those glasses or eye surgery , right iam going to look now .

[Martin@PRD 0]

Funny this thread to appear today, I have just switched the two cam pulleys around from 2 inlet and 4 exhaust on a customers car after someone originally recommended it on here for standard mi16.

 

Finding with the original cam timing of 4 exhaust 2 inlet

 

Engine was run in and then tuned with 1000 miles on the clock, rolling roaded by Mikanices. Peak power of 158 Bhp on the rev limiter 6750rpm limiter and peak torque of 124 lb/ft at 6.1k

 

Engine felt flat until 5.5k where it seamed to pick up a bit, Mike also commented on power output and asked if it had high lift cams as the standard MI16 output on his rollers were 154 Bhp, which I can confirm with customers, friends and my own MI16 over the last 6 years of using his services

 

I wasnt impressed at all with max power at Rev limit and the lack of low down torque, for the road it was useless, today I switched them round to 4 inlet 2 exhaust, wow what an improvement!!! Back to how the engine should run like (4k kick) it feels quicker all the way up the rev band, engine temp has lowered and fuel consumption far better.

 

The engine spec is

 

Fully rebuilt MI16 with new lifters (built myself)

Our Re-angled exhaust manifold

Our shortened Inlet manifold

Our Plug and play Motronic loom and 3 row Ecu

Mi16 gearbox

 

The guy (Martin) is having another rolling road session soon I hope, so we can compare the two power graphs,

 

Myself have seen the 2 exhaust 4 inlet on the 405 MI16 and the 4 inlet 4 exhaust on the BX, this where a think a lot of confusion about the BX being more powerful is due to the different spread of the power band.

 

Another example was my 205 totally standard BX MI16 on Carbs with 3D ignition system standard Gti exhaust system, pulleys were 4 inlet 4 exhausts made 171 Bhp at 6500 and 150 lb/ft as the exhaust cam was retarded

 

I will post the graphs as soon as I have them here to post

[James_m 0]

Why was the limiter coming it at 6750? i thought they are supposed to run round to 7200? or was it running jetronic?

My bad, should have read properly, its on motronic

Edited February 7, 2007 by James_m

[jackherer 543]

Myself have seen the 2 exhaust 4 inlet on the 405 MI16 and the 4 inlet 4 exhaust on the BX

 

I've had plenty of engines out of BXs and all but one have had 4 inlet 2 exhaust, the one exception had 4 inlet 4 exhaust and is the only one I'd ever heard of like that until your post... The one and only 405 engine I've ever had came with 2 inlet 2 exhaust.

 

The combinations I've tried myself are 4 inlet 2 exhaust, 4 inlet 4 exhaust and 2 inlet 2 exhaust. I'm most happy with 4 inlet 2 exhaust but thats only based on feel, I haven't compared on rolling roads at all, but I have tried the different combinations in quite a few different Mi16s.

[Martin@PRD 0]

I've had plenty of engines out of BXs and all but one have had 4 inlet 2 exhaust, the one exception had 4 inlet 4 exhaust and is the only one I'd ever heard of like that until your post... The one and only 405 engine I've ever had came with 2 inlet 2 exhaust.

 

The combinations I've tried myself are 4 inlet 2 exhaust, 4 inlet 4 exhaust and 2 inlet 2 exhaust. I'm most happy with 4 inlet 2 exhaust but thats only based on feel, I haven't compared on rolling roads at all, but I have tried the different combinations in quite a few different Mi16s.

 

Hmm.... Ive seen at least 3 or 4 engines like that, that were removed from bx's with a steel/tin sump, have seen a couple 4 inlet 2 exhaust but thought these had been tampered with, have seen a 2 inlet 2 exhaust on 405's before, I even got a number 3 and a one somewhere but not go a clue where they are from.

 

Will have a look what I have this weekend as there is at least 10-15 of these scattered about my workshop, garage, shed and house.

 

I have used specific cam pulleys in the past and then jumped a tooth between pulleys, though cant remember what they were until they are in front of me on a engine, using over and undersize tensioners can help play with the over lap too but it is recommended to use a dial test gauge on the cam lobes before

 

The v6s engines (ES9J4 and ES9j4S) all come with adjustable pulleys from factory to help correcting the timing with it being a long system with one Tensioner for two heads, I have all ready tinkered with it on both of the engines in my 205, engine in the front has increased over lap which weakens low down power but then increases top end this was to limit wheel spin on standing starts with being fwd and then better top end to dominate power out of corners, the rear engine was set up for low down torque as the weight on the car transmits to the rear on standing starts with slightly less top end as the front engine it should be then act submissive on the upper power band allowing fwd engine to correct the tail, not sure how these Cam timing will affect engine breaking yet but I hope rear engine does the most for entering corners and stability while breaking

[jackherer 543]

Hmm.... I've seen at least 3 or 4 engines like that, that were removed from bx's with a steel/tin sump, have seen a couple 4 inlet 2 exhaust but thought these had been tampered with, have seen a 2 inlet 2 exhaust on 405's before,

 

All the BX engines I've had have had alloy sumps as it happens so that probably explains it.

I even got a number 3 and a one somewhere but not go a clue where they are from.

 

I've never seen a three and I've not even heard of a one before! It seems the threes are more common outside the UK though.

The v6's engines (ES9J4 and ES9j4S) all come with adjustable pulleys from factory

 

I've had a good look at the pulleys on my ES9J4 but I've not played with them at all, its only going into a Xantia auto after all lol. I don't suppose theres any chance the V6 pulleys fit Mi16 cams and cambelts do they?

[Normski 1]

This is interesting. I myself have a Mi16 motor from a 405 and it has #2 pulleys on both cams.

 

I would like to know the general characteristics that each combination will give? To see if it's worth experimenting myself. (For my track car)

 

#2Inlet / #2Exhaust => (my current set-up) A bit lacking below 5K but a really noticeable change in character at 5K, pulls well from there up to the limiter.

 

#4Inlet / #2Exhaust => ?

 

#4Inlet / #4Exhaust => ?

 

#2Inlet / #4Exhaust => ? Moves the torque band up the rev range?

 

Fill in the blanks please.

 

One last thing. Where would I obtain a #4 pulley from?

[Anthony 1,000]

I've had a good look at the pulleys on my ES9J4 but I've not played with them at all, its only going into a Xantia auto after all lol. I don't suppose theres any chance the V6 pulleys fit Mi16 cams and cambelts do they?

Dunno about ES9 ones, but DW10 vernier pulleys certainly fit Mi cams

 

From a quick trial-fit I did with a DW10 pulley, it looks like they'll need spacing about 1-2mm to clear the inner cambelt cover and there's no chance of the outer cambelt cover still fitting on properly with them fitted (would need spacing about 4-5mm or cutting and modifying as the adjuster bolts foul the plastic)

[jackherer 543]

yeah it was the diesel ones that gave me some hope they might fit... I wish I had fewer important jobs to do so I could try some stuff like this out

[taylorspug 7]

This is interesting. I myself have a Mi16 motor from a 405 and it has #2 pulleys on both cams.

 

I would like to know the general characteristics that each combination will give? To see if it's worth experimenting myself. (For my track car)

 

#2Inlet / #2Exhaust => (my current set-up) A bit lacking below 5K but a really noticeable change in character at 5K, pulls well from there up to the limiter.

 

#4Inlet / #2Exhaust => ?

 

#4Inlet / #4Exhaust => ?

 

#2Inlet / #4Exhaust => ? Moves the torque band up the rev range?

 

Fill in the blanks please.

 

One last thing. Where would I obtain a #4 pulley from?

 

Well 2 inlet 4 exhaust moves alot of the torque and power to the upper part of the rev range. Means you have to abuse the motor to get the most out of it, but will reap the best results for a track motor which is singing all day long. 4 inlet 2 exhaust as has already been mentioned gives a wider spread of power and torque, but knocks a bit off the top end. On my engine (which has a set of regrinds in it) this was really noticeable, so much so that i reverted back to 2 inlet, 4 exhaust. Motor seemed far more willing to rev after that.

Im sure a few people have spare number 4 pulleys, so put a wanted post up and see what you get. Either that or get something like one of Peter Ts offset keys to turn a number 2 pulley to a number 4?

 

The number 3 pulleys seem to be most common on the overseas versions of the lower compression MI engine.

[Martin@PRD 0]

All the BX engines I've had have had alloy sumps as it happens so that probably explains it.

I've never seen a three and I've not even heard of a one before! It seems the threes are more common outside the UK though.

I've had a good look at the pulleys on my ES9J4 but I've not played with them at all, its only going into a Xantia auto after all lol. I don't suppose theres any chance the V6 pulleys fit Mi16 cams and cambelts do they?

 

 

All 405's have alloy sump while bxs has tin/steels unlees they have been changed previously

 

No unfortunately the v6 doesnt fit the Mi16 cams as the cam thickness is very similar to the Gti cam, does it fit?

 

This is interesting. I myself have a Mi16 motor from a 405 and it has #2 pulleys on both cams.

 

I would like to know the general characteristics that each combination will give? To see if it's worth experimenting myself. (For my track car)

 

#2Inlet / #2Exhaust => (my current set-up) A bit lacking below 5K but a really noticeable change in character at 5K, pulls well from there up to the limiter.

 

#4Inlet / #2Exhaust => ?

 

#4Inlet / #4Exhaust => ?

 

#2Inlet / #4Exhaust => ? Moves the torque band up the rev range?

 

Fill in the blanks please.

 

One last thing. Where would I obtain a #4 pulley from?

 

2 inlet and 4 exhaust Im not sure about it moving the peak torque further up the rev range if your going on my data in the my previous post, The shortened inlet manifold has a affect on peak torque as vacuum will act differently due to the lower volume between valve and throttle body which increases throttle response

 

Well 2 inlet 4 exhaust moves a lot of the torque and power to the upper part of the rev range. Means you have to abuse the motor to get the most out of it, but will reap the best results for a track motor which is singing all day long. 4 inlet 2 exhaust as has already been mentioned gives a wider spread of power and torque, but knocks a bit off the top end. On my engine (which has a set of regrinds in it) this was really noticeable, so much so that i reverted back to 2 inlet, 4 exhaust. Motor seemed far more willing to rev after that.

Im sure a few people have spare number 4 pulleys, so put a wanted post up and see what you get. Either that or get something like one of Peter Ts offset keys to turn a number 2 pulley to a number 4?

 

The number 3 pulleys seem to be most common on the overseas versions of the lower compression MI engine.

 

I concur with power moving up rev range with 2 inlet and 4 exhaust with the increased over lap, but I find its better with only the inlet cam as the standard engine feel breathless with a standard cr, a modified engine however with higher compression ratio, high lift cam bah bah bah would be more beneficial, but from experiencing the two on a standard mi16 4 inlet and 2 exhaust whether its road, track or sprints has it hands down unless rev limiter was removed but then again cam lift is to restrictive at this rpm

[taylorspug 7]

My engine came from a bx and has an alloy sump. It has the lugs on it to attach to one of the Hydraulic pumps (cant remember if its PAS or suspension though, its been a while since ive seen a BX now).

[Martin@PRD 0]

Hmm thats does make sense, as the 4x4 mi16 has hydraulic suspension, made it was only equiped for these models then?

[Normski 1]

OK, thanks for the characteristics info. I think I shall have a go with a #4 and see what it's like.

 

What about the last combination #4 / #4? How would that go?

[Guest Cartooner]

All 405's have alloy sump while bxs has tin/steels unlees they have been changed previously

 

Nope, mine is from a '89 BX with alloy sump and #2+#2. So far for logic.