Mi16 Engine Lacking Power

[macaroni 17 1 Cars]

Hi all,

 

My mi16 engine feels too torquey down low and somewhat breathless up top.

 

I fitted a supposed PeterT stage 1 cam, bought from someone on here, and a PeterT ecu. I had to source a difference ecu box to fit his chip into.

 

Since fitting the cam myself (which is probably the problem!) it has seemed very torquey up to 3000 and although there is a kick about 5000, it is not as vicious as I remember.

 

I put it on a RR and it was down on power from before the cam fitting, so I suspected the cam timing, which proved to be a tooth out (retarted, I think. Not me, the cam timing).

 

After sorting that out it idles much better but still feels lacking at the top end.

 

I have a stage 2 cam on the way which I'll get professionally fitted with a thin MLS head gasket and possibly a rebuild with new rings etc.

 

However, in the meantime is there anything else I can check to ensure the engine is doing what it should?

 

Compression is good apart from no 2 which is slightly down, but the others are around 200psi.

New plugs, leads, dizzy cap, rotor arm, ignition module, CTS and replaced AFM (but not refurbed).

 

Any help gratefully received.

 

Cheers,

 

Antony

[petert 554]

If it's mine, it will be marked 426B on one end. It should have 0.065" lift @ TDC if installed correctly. Once verified, you can then do a compression test.

 

What's does "slightly down" mean?

[macaroni 17 1 Cars]

I can't remember what was stamped on it now and have no way, or idea, of measuring the lift.

When you say "installed correctly", how can I get it wrong?

 

All caps were torqued to the recommended rate, standard inlet pulley (no 4) and keyway was used and all the timing holes lined up. At the 2nd time of asking!

 

Slightly down is about 170 psi, as opposed to the other 3 being at around 200. Not disastrous, but anomalous.

They all go up by about 20psi when rechecked wet, by the way.

Edited October 9, 2012 by macaroni

[petert 554]

The #4 pulley will advance the cam a bit more than ideal, meaning less top end. There can be variations with engine builds, so only measuring the exact position of the cam will confirm whether it's in or near the right spot. A #3 pulley is ideal.

 

30 psi down is a lot. I wouldn't bother trying to instal the Stage II cam until you rectify the problem.

[Tom Fenton 1,526]

As Peter says there is no point going "up" a cam to try and restore power that isn't there in the first place.

 

With the uprated cams it isn't really good enough if you want the best possible power just to bolt them in on the standard pins, you need a DTI to accurately time them in and then potentially vernier pulleys to get them spot on.

[petert 554]

You will definitely need a DTI to dial in the Stage II cam.

[macaroni 17 1 Cars]

As Peter says there is no point going "up" a cam to try and restore power that isn't there in the first place.

 

I fully agree and have no intention of doing that, hence this thread.

 

The no 4 pulley was on the engine when I received it and it produced 145bhp at fly (please no long debates about this!), now its producing less.

I accept that the reduction in compression of no 2 cylinder might be partly responsible for the reduction in power from 160-ish, but why less power now?

 

With the stage 2 cam, as said, I will be getting it done properly, probably with a rebuild, but that won't be till next year.

 

I just want to find out what's going on now.

 

So if the no 4 pulley advances the inlet cam too much, should I try a no 2? I only ask this as I have a no 2 pulley handy, or should I get hold of a number 3?

 

The car also seems very rich, it certainly was on the recent power run before I corrected the cam timing, would the use of a no4 pulley have this effect or should I be asking the AFM some searching questions?

[welshpug 1,626]

1, get a dial gauge.

 

2, find why its down on compression.

 

3 fix rich running issues.

 

sticking on different pulleys without confirming the lift @ TDC is worthless, and wont fix your loss of compression, altering timing belt tension on these can throw out the timing, especially given they have the two tensioners.

 

my own 2.0 mi was rr'd before a belt change and it was massively down on power and up on torque, I don't remember the exact figures, something like 140 bhp, its now 160 bhp/180Nm.

Edited October 9, 2012 by welshpug

[macaroni 17 1 Cars]

OK, no quick fix here then I guess!

 

Thanks for your input and advice.

[Stu 18]

I do feel obligated to pipe up seeing as though it was me you bought the cam from.

 

There is no 'supposedly' about the legitimacy of the cam, myself and Peter had lengthy debates about my 'ideal' setup with regard to keyways and such and he supplied me with the cam after him providing a cam to grind to save me stripping my engine to ship a 'donor' cam across. He will happily confirm this i would imagine.

 

There is a build thread of mine knocking around somewhere, documenting that phase of the engine build showing the cam install.

 

Anyhoo, back to topic and off my soapbox.

 

As most have mentioned, i'd be interested to see what the valves were like if its been ran a tooth out, could explain the compression problem...

 

It it 'smells' rich then the first thing i would do would be change the CTS, its the most likely culprit.

 

It seems there are a number of 'minor' issues all contributing to your power loss, Mi's are very sensitive to compression changes, hence why Peters cam works so well with engines running slightly hotter than usual. I certainly had no issues with mine with it installed, though i did initially run it on verniers to dial it in exactly, then switched back to stock pulley after returning the engine back to standard.

 

For me, i'd swap the CTS, verify the cam timing then think long and hard about wether you can justify rebuilding it to sort the compression problems.

[macaroni 17 1 Cars]

Hi Stu thanks for your input,

sorry, I wasn't questioning the legitimacy of the cam, far from it, just inferring that I didn't buy it myself. Absolutely no offence meant at all!

 

I'll have a look for that build thread, should show me what I've done wrong.

 

The compression anomaly was there before the cam being fitted and there was no knocking with the timing out, so I don't think anything was touching. It does suggest that the head hasn't been skimmed much, or at all, in its life so I'm comfortable going for a thinner head gasket.

 

I have changed the CTS but I did replace the AFM, so I suspect that. I can try the CTS again, they're pretty cheap.

 

Interesting you say that about engines running hotter, as since the cam install the oil temp goes higher than before. Unless I've done something wrong, which I still suspect is the case.

 

Why do you say to think long and hard about rebuilding it?

[Stu 18]

My bad, i may have read that a little wrong then! No offence taken anyhow so we're all good..

 

When i said 'hotter' it was a poor choice of words tbh, i just meant running a little more compression...

 

If you've changed the CTS then unless its been a while ago it probably wont need doing again, they can be checked with a multimeter and a pan of water anyhow if in any doubt, i would always favour a 'tested=known good' sensor than a new one any day of the week!

 

When i say think carefully about rebuilding it, i just mean they can be expensive, my build probably cost knocking on for a grand once all was said and done, but that was everything including a BBM hose kit, all the sundries, paint and the like, funny how all the little bits add up over time!

[macaroni 17 1 Cars]

Ah, lots of mis-communication!

 

It was a new CTS, from Pug, so I kind of assumed it was a good one. I'll get the kettle on and check it.

 

Actually I had budgeted about a grand for the rebuild and am happy to pay that for a well-performing mi16 engine.

If that could include the cam, thinner MLS HG, head set, belt, rings, hone etc I'll be happy.

 

The main thrust of this thread was that acknowledging the issues with the compression, the car now produces less power than before I fitted the stage 1 cam and for suggestions as to what I have done wrong.

[Tom Fenton 1,526]

With the uprated cams it isn't really good enough if you want the best possible power just to bolt them in on the standard pins, you need a DTI to accurately time them in and then potentially vernier pulleys to get them spot on.

[wicked 103 3 Cars]

If the timing is not correct, you don't get enough air in the engine, but the amount of fuel that is injected remains the same; so it will run richer (or too rich).

 

Just get you hands on a '3' pulley as PeterT indicated... shouldn't be too hard to get one?

[welshpug 1,626]

suggestions as to what I have done wrong.

 

not checked the glaringly obvious, WHY HAS IT LOST COMPRESSION.

 

 

It will not be the cam timing given its one cylinder.

Edited October 10, 2012 by welshpug

[macaroni 17 1 Cars]

The compression issue was there before the cam install so I always intended to get that sorted at some point.

 

I'm not suggesting the cam is causing that at all.

 

The compressions increase by about 20psi per pot when checked wet so I think its a safe assumption that the rings are to blame.

Having said that, it doesn't smoke at all, or use any oil and they all increase by the same amount, so maybe its a head gasket thing.

 

It seems my issue is with timing. I'm pretty sure it is now timed correctly, so I'll work on the pulleys.

 

Then I'll be after someone to work on the engine next year.

[macaroni 17 1 Cars]

To resurrect this, I think I got the timing as good as I can; tight belt with finger tight locking pins.

 

I've also had a little fiddle with the AFM and it now seems to go very well; rock solid idle, good torque up to 4000rpm, then really flies above 5k.

 

Its definitely going as good as it ever had in my hands, so got it booked on my local RR tomorrow for an AFR check and power run.

With the engine in its current state I'm hoping for around 150bhp, then I'll have it rebuilt in the new year ready for my PeterT stage 2 cam.

 

I'll update with my graph over the weekend to give you all a good laugh...

[kyepan 291]

Speaking from my experience with the stage 1 Cam, going from a #2 pulley to a #4 pulley on this cam definitely enhances the power band a noticeable amount, and will result in it scrabbling past 3-4-5 then taking its time after that, before it was linear and then had a little scrabble towards top end. But it definitely works better on a vernier

 

Dialling it in on a vernier to it's specified reference lift ATDC will result in a bit more top end than a #4 but no where near as flat as a #2.

 

Just so you know from another person with this cam, it's a good road cam, and timing does make a difference, but it's not a screamer.

 

 

 

J

[macaroni 17 1 Cars]

That's exactly how it feels on the road Justin, with the stage 1 cam and no. 4 inlet pulley.

 

So just come back from the RR and...

 

first run, Aug 2011 - 144bhp @ 7050rpm (standard and with knackered AFM)

2nd run, about 6 months ago - 137bhp (replaced AFM, fitted stage 1 cam, but got timing out by 1 tooth on crank pulley)

3rd run, today - 161bhp @ 6717rpm (corrected cam timing, tweaked AFM; moved the sprung wheel anti-clockwise by 4 teeth)

 

This I am very pleased with and just goes to show, if you get things right, they work!

So thanks for all your help and advice guys.

 

 

Disclaimer: all figures are output from RR at flywheel, same rollers for all runs, usual caveats about rollers apply.

What I will say is that I had my Alfa 156 2.4 20v jtd on there and it made 181 (stock - 175), so they're quite close.

 

Next week, my 156 GTA has a go!

[welshpug 1,626]

I'd be a little disappointed given they're meant to be 160 with stock cams...

 

what was the torque like?

 

 

have you fixed the compression issue yet?

[RP1983 4]

It seems like you have got a good increase from getting everything closer to how it should be.

 

Do mi's usually make peak power that high up? I'm yet to put mine on rollers but to me it feels like my peak would be about 6k, I certainly never feel the need to rev past 6.5k which has got me thinking now seeing your results.

 

I had the same issue with mine when I first had it of it feeling immense bottom end and not much up top but after changing afm and sorting the cam timing I thought it was about right, maybe not though.

[kyepan 291]

pretty much what I got before the rebuild with a number 2 163bhp. After it was nearer 170 on a number 4.

 

how much torque?

[macaroni 17 1 Cars]

Welshpug, its a stage 1 cam and no other mods, so I'm very happy with 160!

Not got the compression issue fixed yet. I spoke to the guys at HTRacing, where the RR was, about a rebuild in the new year and they seemed happy to.

They usually do Ford engines, as Vulcan Engineering, but have done a few XU9 8vs apparently.

 

Torque was 130lb at 5930rpm. I will put up a pic of the graph later from home.

 

RP, getting things right certainly helps! mine does seem to be most aggressive the higher the engine is spinning, right up to the redline at above 7000rpm.

In 1st, 2nd and 3rd gear I often hit the limiter.

[macaroni 17 1 Cars]

Sorry Justin, didn't mean to ignore you. You posted while I was typing.

Not sure why it wasn't nearer 170, as I am using no. 4 pulley, but no matter, it feels great and fuels right.