[engine_work] Xu9j4 Mi-16 Rebuild

[cheesegrater 43 1 Cars]

BEST RESULTS EVAR!!!!11!

[welshpug 1,666]

moar vids ! maybe some in gear timing to see how quick it actually is ?

[DrSarty 90 1 Cars]

I'm impressed Justin...but not overly surprised.

 

What I mean is, your efforts (along with 'your gang') have paid off handsomely. And I completely agree with Anthony's summary of how peak BHP is not a true reflection of either performance, work done, or tractability (usability) of the power plant. You should be proud.

 

The discussion which looms - if you require it to, formally or in social circles - is where do you go next, if anywhere at all, as the latter is possibly the hardest choice?

 

What I mean is, for the benefit of all interested in motorsport tuning at a consumer level, what would you 'have' to do next to increase performance/figures, focussing purely on the engine itself?

 

(At last....my chance to don the flamesuit!)

[kyepan 291]

Well there is some more to the story - so i don't want to get ahead of myself but....

 

I missed a trick during the build, i had the block and liners faced to get the liner protruderance correct, i could have had it decked at the time to get an 11:1 compression ratio, Paul Gardias even asked me at the time.. and was suprised when i turned him down on the offer. Had that happened, at this point i would be looking at matching that compression ratio to a suitably lumpy duration cam. However, I missed the trick. I could still run a 275-280 cam, and get 200+ bhp, but the question is what it would do to my nice mid range.

 

For the time being though, i have some other things to sort out.

 

1) Fuel rail bodge, and other fuel supply related changes -i'll update on this later today, as it was only ever temporary... despite having been perfectly leak free.

 

2) Taco - rev counter, we tried soldering it using the method listed on here, even went through the pcb trying to figure out how bypassing those capacitors worked, but allas i have to rely upon the shift light sandy added to the loom.

 

3) Modify the cam belt cover so i can keep the weather and ambient moisture off the cam belt area.

[DrSarty 90 1 Cars]

On that basis then, anyone could assume that a block and appropriate liner height reduction (or 'decking'), perhaps at a cost of £200 or so, would net an extra 15bhp! (Hence the flamesuit).

 

I'm merely speculating on the cost per horsepower, which as we (hopefully) know, is a law of diminishing returns, i.e. an extra 5bhp once you've added 10bhp may cost twice as much and so on.

 

Naturally I'm only focussing on peak bhp, however with the approach you've applied throughout, it's inevitable that you will achieve gains across the rev range.

 

So in short, and being more specific, what would one/you have to do - and at what cost - to make the next step up in output?

[kyepan 291]

I don't know is the short answer.

 

 

Long answer is to do with camshafts because the twin injector bike body setup I have matched to the exhaust manifold is as optimised as it can be.

 

Theoretically we know what will happen with longer duration cams that "peak" later. And how that will affect the torque curve. I know the heads been skimmed a couple of times, and the block has been faced (we're taking about 3-5 thou), so i can't really calculate the compression ratio accurately, or the dynamic compression with any given set of cams.

 

In an ideal world it's got enough compression to take more cam without affecting low and mid torque. Ideally it could continue to make that much torque until later in the rev range, (with the resulting higher headline figure) and perhaps as kates engine showed, even more torque... 12ftlbs more IIRC.

 

PeterT's stage 1 cam (what i have), advertised as 260 duration, If we assume that it's inlet closes 60 deg ABDC, and my compression ratio is 10.6:1 (also assumes rod length is 159mm)

 

Static compression ratio of 10.6:1.

Effective stroke is 68.92 mm.

dynamic compression ratio is 8.69:1 .

dynamic cranking pressure is 176.90 PSI.

Your dynamic boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0 PSI is 8.69 :1.

V/P (Volume to Pressure Index) is 849,866

 

then on a 270 deg cam same compression ratio and 65 ABDC inlet close(general figure according to my book on camshafts).

Static compression ratio of 10.6:1.

Effective stroke is 66.02 inches.

Your dynamic compression ratio is 8.37:1 .

Your dynamic cranking pressure is 168.55 PSI.

Your dynamic boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0 PSI is 8.37 :1.

V/P (Volume to Pressure Index) is 775,683

 

and then finally, 280 deg cam, same compression inlet closes 68 deg ABDC..(general figure according to my book on camshafts)

 

Static compression ratio of 10.6:1.

Effective stroke is 64.19 inches.

Your dynamic compression ratio is 8.17:1 .

Your dynamic cranking pressure is 163.37 PSI.

Your dynamic boost compression ratio, reflecting static c.r., cam timing, altitude, and boost of 0 PSI is 8.17 :1.

V/P (Volume to Pressure Index) is 730,968

 

Summary -

DC 260 8.69:1

DC 270 8.37:1

DC 280 8.17:1

 

and I still don't know.

 

cheers

J

Edited July 19, 2012 by kyepan

[DrSarty 90 1 Cars]

Interesting stuff.

 

I suppose what I'm really querying is myself and my own logic, as to how your engine or any engine for that matter could be 'improved' once you've ticked the boxes you have. Being even more blunt, have you basically got close to maximum, healthy output for a N/A 1905cc D6C engine?

 

By healthy I mean your decent match of torque and power, where any further tuning is a relative gain not at the cost of a large loss somewhere. (Forced induction is left out of this)

 

My mind therefore is only thinking the following, with total guesses on cost in brackets:

 

- swap cam & tweak timing / possible shift to right of delivery giving higher peak bhp but flatter mid-range (£150 cam + £150 RR = £300)

- headwork & change to solid lifters (also with above cam) (£600)

- block & liner decking to increase CR (plus above) (£200) perhaps done in addition to below

- forged pistons & other bits (crank work or swap) to permit higher RPM (£1000)

 

This is purely hypothetical J, and I'm not suggesting for 1 minute that you're going to do anything else to your engine.

 

I'm merely pontificating as to how engine tuning works, even in general beyond what you've done now, how much it might cost for what gain(s), and ultimately - my main point - how soon before you reach the practical and financial sense limits of this engine before one/you has to consider a different power plant and/or increased displacement?

 

Final question then really is, is there the 'best' Mi16 1905cc N/A engine out there somewhere?

[kyepan 291]

Anthony said I should just enjoy it. So this evening thats exactly what I did..Baz is only a short drive up the m11 so I popped in and we went for a spin, he showed me how to drive a 205 on its door handles and upside down, car control skills worthy of respect. Then I took bat for a run, and struggled to reach the peddles. Then Baz had a go in my car to give have a feel of how it handles, he also gave the engine a thorough spank..

Edited July 19, 2012 by kyepan

[petert 600]

Going above 10.8:1 with the Stage I cam would have been too much CR. You could have retarded the cam timing a tad to give a more impressive hp figure, but you'd loose the fat mid range. The cam position I advise gives an LCL of 109º. Most cam suppliers suggest around 112º for similar sized cams, but I think the results speak for themselves.

 

Yes, you can still go bigger on the inlet cam timing with 10.8:1. Also, rod length is 143mm for the XU9's.

[kyepan 291]

Think mine is probably nearer 10.6:1 though Peter

[petert 600]

What hp at the wheels was it?

[petert 600]

Still good for the camshaft choice however. As said, just enjoy it and be pleased with your efforts. Else you'll always be chasing rainbows. What cwp are you running?

[kyepan 291]

You mean good output for the stage 1?

It was 153.7 at the wheels, and 128ftlbs of torque, sorry what is cwp?

[TT205 42]

Crown wheel/pinion

 

Is it from a 1.6, 1.9, Mi16 etc

[kyepan 291]

Crown wheel/pinion

 

Is it from a 1.6, 1.9, Mi16 etc

ahh thanks! 1.6 with an ATB diff.

[petert 600]

Being an aussie made DynoDynamics dyno, it's more plausible to compare notes with. We only talk in hp at the wheels over here. Your value of 154hp (114kW) is on the upper limit of what I've seen from similar spec'd 1905cc engines on TB's. I've certainly seen worse. eg 107kW with Stage II inlet/Stage I exhaust cams. Also, a big valve engine I know of also made 114kW with a Stage II inlet. So yes, I think your efforts are excellent.

 

It should be great to drive with the 1.6 cwp. Enjoy!

[Baz 421]

It is great to drive, mid-range torque is fantastic, just feels like it's begging to be 'unleashed' even when cruising along at relatively low rpm, characteristics of what is almost the opposite of a generic Mi, to be expected from the long inlet length but more than i expected!

 

As a result though, and this isn't meant to criticise at all, just some perspective for others, it still has power up top, but it just feels un-Mi like, it doesn't need to be revved right out, certainly isn't worth taking to the limiter as you can feel it tail-off a fair whack earlier.

For me personally, not disputing the pure tractability of it and don't see this the wrong way as i think Justin knows what i mean, it almost feels a little underwhelming.

It isn't though, far from it, - hard to explain what i mean, but i know it's because i'm not only used to, but love the peaky nature of 1.6's & Mi's etc, begging to be thrashed to, and feeling as if they want to go beyond the limiter, so for me at least, i can see it might get that way after getting used to it, but that's like anything. It certainly doesn't 'feel' as quick as my previous Stage1 inlet or even standard Mi's on bodies, but in realistic terms i think that has more to do with the car itself being quite refined, so no i'm not saying it's slow! It's quick, & i think it would actually be on equal terms with them, at least because you don't have to ring it's neck as much!

 

What Justin's done is built a bloody good Mi here, i think that alone deserves respect these days, sticking with the original daddy 16v and persevering, hat off for that! If it was mine, i'd be damn chuffed with it and echoing the already said, would just enjoy for now, but if i'm honest thoughts of a bigger cam would be in my mind... It's rekindled an old plan i've had for years as it is!

 

Last night was a pleasant evening gifting some of Hertfordshire's finest by-passes & country lanes with a glorious induction-hammer laced Mi soundtrack. Thoroughly enjoyable and exactly what 205's are about! -Thanks J.

[SweetBadger 94]

Well there is some more to the story - so i don't want to get ahead of myself but....

 

I missed a trick during the build, i had the block and liners faced to get the liner protruderance correct, i could have had it decked at the time to get an 11:1 compression ratio, Paul Gardias even asked me at the time.. and was suprised when i turned him down on the offer. Had that happened, at this point i would be looking at matching that compression ratio to a suitably lumpy duration cam. However, I missed the trick. I could still run a 275-280 cam, and get 200+ bhp, but the question is what it would do to my nice mid range.

 

For the time being though, i have some other things to sort out.

 

1) Fuel rail bodge, and other fuel supply related changes -i'll update on this later today, as it was only ever temporary... despite having been perfectly leak free.

 

2) Taco - rev counter, we tried soldering it using the method listed on here, even went through the pcb trying to figure out how bypassing those capacitors worked, but allas i have to rely upon the shift light sandy added to the loom.

 

3) Modify the cam belt cover so i can keep the weather and ambient moisture off the cam belt area.

 

Hi not been on here in a while as my pug is currently sitting unloved in a garage as I deal with now having a mortgage, but thought i'd post as there's a cheap and easy way to get around the compression. Fit a cometic 0.7mm thick MLS head gasket - costs about £90 (special order takes about 4 wks to arrive). I know some people don't think mls + open block mix, but I've been running one on mine for about a year inc about 6 trackdays and it's been fine.

[kyepan 291]

Finally been able to give the car a good outing and find out what it's really made of. The slightly iffy feeling rear turned out to be a very dead rear wheel bearing so it felt solid suspension wise for the first time in ages.

 

My route from london to beccles where we were competing in the Club 100 endurance series (100cc 2 stroke karts) was M11, A11, A14, A143 (the 143 is a fab road, lots of long sweepers and great big expansive straights).

 

Basically i'm pleased as punch, the car quite happily and safely took me past two or three cars at a time, sponk loads of torque everywhere, and after learning to shift a little bit shorter it's just a super effective A road car. I've got to record the noise, as it sounds unlike most ITB cars, less bark and more muted gargle.. i'll get a video, as i'm sure that doesn't make sense

 

I'm going to leave it alone for now and enjoy, then perhaps next year think about some cams with a bit more lift and some duration.

 

Thanks to Paul_13, Anthony for their help on the engine, Paul Gardias for the machining, and Sandy for the advice on exhaust, the bodies and mapping.

 

Ps we came third in the race, slightly too larger gap to the leaders for me to close in the last double stint, and a longer brake pedal than earlier in the day meant it took me a few too many laps to get on the pace.

 

J

 

 

Hi not been on here in a while as my pug is currently sitting unloved in a garage as I deal with now having a mortgage, but thought i'd post as there's a cheap and easy way to get around the compression. Fit a cometic 0.7mm thick MLS head gasket - costs about £90 (special order takes about 4 wks to arrive). I know some people don't think mls + open block mix, but I've been running one on mine for about a year inc about 6 trackdays and it's been fine.

thanks for that!

I did consider it at the time, but decided against it in the end.

[Sandy 191]

When I said to you Justin, that I thought it was like a "super 1.9", I meant an amplified version of the 1.9 8v delivery, by no means a peaky delivery; lots of eager grunt, responsive and meaningful thrust without having to wring it out all the time. I've often had comments along Baz's lines about my engines and when the mid range is good, you do lose the sense of crescendo that you get when mid range is weaker, which makes the top end seem better in relative terms. I always take that on board obviously, all subjective feedback is relevant; but for most people, most of the time, mid range performance makes the car easier to drive briskly and (although not strictly relevant here) in competition we've prove continuously, it is quicker like that and less thrashing makes the engine more durable and reliable.

[Batfink 201]

pub talk figures say you can get 200bhp with your spec, yet to date i've never seen one make it. Yours is one of the most powerful i've seen. It sounds and feels fast in the passenger seat!

I'll hunt out my rr graph from when I owned the engine all be it fitted with Jenveys and a standard off the shelf maniflow. That made 176bhp at fly off the top of my head.

[Anthony 1,003]

You could almost certainly increase the peak hp figures on Justin's engine merely by retarding the inlet cam a few degrees, but whilst that would be good for pub bragging rights, it would almost certainly make the car slower overall.

 

A good example that you would know would be Kate's final Mi16 - that made 196hp from memory with TB's, maniblow and a Catcam 526 inlet, but the cam timing was a little retarded on it and whilst it screamed if you kept it on the boil over 5k, it certainly lacked the mid-range grunt that Justin's has.

[petert 600]

Vrrooooom!

[kyepan 291]

The car has developed a rather impressive oil leak. I have yet to discover its source. All down the front of the sump in between the flywheel and box. Going to get it on the ramps tomorrow and clean it off. One of the breather joins looks suspect. I fingers crossed its not crank shaft deal related.

[GLPoomobile 958]

Guess it was about time for your car to remind you how much it hates you Ungrateful bastard