[engine_work] Xu9j4 Mi-16 Rebuild

[Henry 1.9GTi 36]

sorry for being a lazy reader but whats the rough spec of this engine?

[kyepan 291]

sorry for being a lazy reader but whats the rough spec of this engine?

spec - sandy said OK ish, it's a pretty basic engine, but the inlet/bodies and exhaust are the bizniz and mean i've got bags of torque everywhere.

 

Inlet is an 8 injector gen2 satchell and brown GSXR setup, exhaust is a super long primary 4-2-1 that sandy recommended.

 

 

I also feel the need to quantify what bags of torque means, and why i feel it has bags more of it than the average MI on bodies, so below is a graph i've been quietly keeping to myself for ages.

 

Kate's old mi with

 

• Catcam inlet
• Short puma bodies
• Short maniflow 4-2-1
• Mild porting head

 

Superimposed over my

 

• Peter t 260 inlet
• Long Satchel/brown bodies 8 injector
• long 4-2-1maniflow
• Mild porting head
• Standard ish compression
• Balanced

 

I took quite a bit of time and care to get the scales right so it should be pretty faithful, i left them on the right, hence it looks a bit messy.

 

 

 

Yellow lines are Kate's power, just look at the higher one

Purple dotted are Kate's torque, again just look at the higher one.

 

The dark blue line that crosses Kate's power line at 6750 is my power, as you can see it only makes more power over 6750...

 

The dark blue line that is generally tracking 10-30 ftlbs higher than Kate's torque is my torque.

 

Now - the reason for posting this is to point out that these engines are pretty identical on spec, even down to the cam, the only real difference is the long inlet and long exhaust and the 8 injectors, lets say for the sake of argument the mapping is identical (although i doubt it is).

 

And if you wanted any more evidence that the engines are similar, notice my old standard engine on standard inlet and standard exhaust tracking a near identical torque trace to Kate's

 

So, the point of this is, to shout from the rooftops about sandy and colin's ideas, because they clearly work, demonstrably. And secondly, point out that very similar spec engines with headline figures that point one way, 193 vs 185, can point the other way when you superimpose them.

 

Current spec, has a bit more cam, and a bit more compression but otherwise identical, I'll get the new cams rolling roaded at some point, see if it has affected the torque, and see if it breaks the 200 mark, because i'm sad like that.

Edited July 31, 2013 by kyepan

[Sandy 189]

Thanks for that Justin, sometimes I think i'm going mad trying to explain to people the difference between well developed inlet/exhaust designs and just bolting something on! Interesting that your personal inlet kit was rejected by a known Peugeot engine builder, blamed for their engine not making expectations; what did that customer ended up with on their own kit? A bit more power and alot less mid range...

 

Give them chips... chips is what they want.

[kyepan 291]

I guess this would have garnered a bit more interest if it had been it's own topic, but hey ho.

[Sandy 189]

Perhaps, but it is only of interest probably to people who appreciate the issues and hopefully they'll already see it. My chips remark is about giving people what they want. Most people are most interested in revving higher, more noise=more power=faster etc and the crescendo effect that follows a dip in the delivery is often exciting and subjectively seems fast, even if true performance comes better another way. I don't really want to try and say what's right for everybody, all I know is less revs means more reliable, better performance under the curve is faster in general and I feel like I've achieved something if I can find more punch, rather than more top end.

[DanteICE 72]

A racing driver once said, it's torque that wins races. Didn't quite get it at the time, but it makes sense now. You can see that it's all about torque in WRC because their engines pull all through the rev range, because they can't guarantee they'll take every corner properly and in some cases you just can't. (I might be totally off with that one, but it makes sense in my head.)

 

Kyepan, I find this very interesting and something I've always known about but never really seen the evidence, I just accepted it. But I've always thought road cars need less top end and more mid range, BECAUSE they are road cars. The honda engines make great power, but on the road I wouldn't say it was usable. I have a friend with a Civic Type R and he says it's fast, but it's not an easy drive because you got to wring its neck to get it to go anywhere and with his father in law in the car he feels it makes him look like a lunatic.

 

Geoff

[petert 549]

[kyepan 291]

right - surrey rolling road says... 160 hp at the flywheel...

 

something is clearly amiss, watch this space.

 

J

[welshpug 1,621]

at what RPM and what torque Justin?

[Sandy 189]

Does it feel broken, or is this another case of rolling road randomness?

[kyepan 291]

surrey is quite reputable, and where i took it last time to have the power read.

 

2012 mapping, 172 atw whilst mapping, 185 at the fly the next day at surrey

2013 mapping, 182 atw whilst mapping, 160 at the fly 3 months later.

a porsche that was on previous to my car made expected figures, if not a smidge more.

 

I'm going to plug in and check the sensors, then obvious stuff like plugs leads etc.

 

If i'll be honest sometimes it feels like a rocket, other times lacklustre, certainly doesn't feel broken, sounds fab.

[kyepan 291]

so far:

 

Air temp sensor: reads ambient temp

Water temp sensor: reads and climbs normally

Plugs: look almost new

Leads: are not arcing

Coil: was new a month ago

TPS: reads bang on where it was set, can get full throttle no problem.

Oil temp: no reading, but the gauge works.

 

Looked down the bores, they all look okay, plugs were in tight.

 

None of the vernier pulley bolts were loose

Cambelt tension seems fine.

 

will try an put up some photos of graphs.

[Batfink 201]

There's no way your car makes the same power as my old engine did.

[Sandy 189]

There's no ****ing way that engine's only 160bhp if it's as it was when I did it! Don't trust DD rollers too much, they do spit crap at times, even with other cars seemingly about right.

[kyepan 291]

here is the old plot against the new plot, old plot blue (higher) new plot red, lower. With AFR trace.

 

 

And new power and torque at the flywheel / wheels (i think)

 

J

[Sandy 189]

Almost looks like the Tx loss adjustment is missing! AFR is stable enough, maybe he didn't get the pedal properly to the floor? Possible collapsing exhaust?

Edited October 6, 2013 by Sandy

[kyepan 291]

I am most perplexed! to say the least Sandy. It just makes no sense.

it was the 4x4 rollers, had a porsche on before, using the rear set, then mine on straight after using the front set.

 

My inital thoughts were dying fuel pump, but wouldn't that show up on the AFR trace.

 

Exhaust wise, you mean one of the boxes? as it's got the maniflow SB spec manifold, and stainless "longlife" everything else.

Cheers

J

[Sandy 189]

A collapsing silencer, but the AFR would usually go richer with it, but if it's being read at the tailpipe, the readings are typically leaner. That area around 5k probably wouldn't look the same with the sensor in the system.

[kyepan 291]

Have bought a cheap endoscope with light, lets see how we get on.

Edited October 7, 2013 by kyepan

[Batfink 201]

i think you have to use the seat of your pants test. Does it feel slower? - answer: no = ignore the result

[kyepan 291]

right covering bases.

 

Got a new bosch pump on order, phase 2, for 91 plus vat, which is not much more than a wallbro, and a lot less hassle to fit

Also have a new set of the bcp7et tri electrode plugs that it was mapped on, rather than the cheap single electrode ones…that i fitted after.

Lets see if that makes a difference.

[kyepan 291]

i think you have to use the seat of your pants test. Does it feel slower? - answer: no = ignore the result

subjectively sometimes it feels off the boil.

[Anthony 1,000]

Given that the AFR's are staying in the low 13's at full revs/load I'm far from convinced that the fuel pump is at fault.

[welshpug 1,621]

Nothing wrong with cheap single electrode plugs.

[Rob Thomson 6]

Got a new bosch pump on order, phase 2, for 91 plus vat

 

Do you mind if I ask where from?

 

Cheers.