Mi16 On Cams & Bodies Finally Mapped - Results

[SweetBadger 94]

Had my MI16 mapped last week at Track-n-road.

 

Spec as follows:

 

- 1905cc standard alloy block MI16 engine
- Block & liners decked by 0.4mm (10.8:1 compression)

- Standard head, 3 angle valve seats, brand new pug hydraulic lifters

- Newman PH4 inlet cam, PH3 exhaust cam

- Inlet cam set to 2.1mm lift @ TDC, Exhaust cam set to 1.8mm lift @ TDC

- Lotus 45mm throttle bodies mounted on Satchell inlet manifold

- 330cc Injectors running @ 4 bar

- Generic looking unknown 4-2-1 exhaust manifold

- Pug Racing 2.25 inch exhaust.

 

Headline figures 187BHP @7700 rpm, 141.1 lbft @6444

 

 

Had a good day out at track-n-road, and they really seemed to know their stuff. Was pretty nervous about the car as I wasn't able to get it running on a base map and get it up to temp to check for issues, but they had it running and idling well within what seemed like a couple of minutes, and all seemed good. The top end is really quiet with the new lifters.

 

Steve wasn't impressed with my choice of Gti6 injectors, with them being old technology and possibly a little undersized. Then about 20 mins after the mapping was started while mapping steady state at 1500 rpm the engine wasn't behaving, and it became apparent that cyl 3 was running rich. One of the injectors was sticking open - bloody annoying as I'd had them cleaned and tested before installing them, maybe it didn't like running @ 4 bar.

 

I thought this might be the end of the day, but luckily they had a spare set of more modern plastic body 330cc injectors, so old injectors went in the bin, we installed the new injectors and the mapping had to pretty much start again as the fuel maps couldn't just be scaled for the new injector size.

 

Once that was sorted the rest of the mapping was uneventful, and the car behaved itself, phew!

 

Car set up on the rollers:

 

 

 

Power graph:

 

 

 

The rev limit was set to a soft 7600 rpm / hard 7800 rpm, with the shift light at 7100 rpm, which is nicely within the limits of the standard valve train / bottom end.

 

To be honest I was a little disappointed with the figures it made (was expecting around the 200bhp mark), but the guys reckoned the figures were what they'd expect, and that their rollers give pretty accurate figures. They often see lower figures on their rollers with customers arriving with expectations based on dyno runs from a different rolling road being disappointed with the final power figures.

 

So basically if I pick the right rolling road I may well get the shiny bit of paper with 200hp!

 

I was surprised that the cam timing wasn't moved around to see if it could be optimised, but I guess looking at the graph it peaks at the right point.

 

As soon as I went for a test drive the disappointment over the figures disappeared! The thing really does shift! The roads have been damp since I've had it mapped, and it just spins up the wheels in 2nd and 3rd gear as the mo! And the sound from those throttle bodies :D .

 

The engine is cammy with these cams installed - it will happily pull from 1500rpm, but it's a little lacklustre until above 3500rpm. This is fine for my car as it's only really be used on the track now, but if I was putting an engine together for a fast road car I'd be looking for a milder cam.

 

I think that it might also be worth changing the exhaust manifold - from reading kyepan's build thread it looks like the maniflow manifold he fitted gave good results, but that'll have to wait, as I need to focus on the suspension / handling next.

[rallyeash 155]

Nice one. Most important thing is how it drives.

[Simes 248 2 Cars]

Nice, good results.

Similar spec to mine, similar results.

Got to love an Mi!

 

262 cams

3 angle valve seats

Fuel running at 3bar

Gti-6 injectors

Mani flow 4-2-1 with oe exhaust.

Jenveys

Emerald ECU.

Mapped by Dave walker.

Limiter is set to 7400.

 

Mine comes on cam around 4500 and then it's off.

You'll be hunting out tunnels for WOT, you can hear mine from miles away; it's all about the induction sound!

[GilesW 41]

What figures did Dave give you Simes?

 

 

Interesting thread though as early in the new year I'll have a similar engine to go down TnR for mapping.

 

 

Only differences:

Sandy manifold

Manilfow exhaust manifold.

Kent cams - 1604 & 1603

Longman head

Jenvey 45's

 

 

 

The Steve's seem to always produce a nicely behaving car after a session.

Re your figures - I can understand your disappointment. My Tb'd vaux XE engine took another £3k to get from 240 to 267bhp which is where I thought/hoped I'd be on teh first engine build.

[Simes 248 2 Cars]

194bhp and 151 torque.

Graphs are similar and in my rebuild thread.

Daves rollers are slightly optimistic.

[petert 586]

Forget the flywheel figure, it's got 160hp (119kW) at the wheels, with +/- a bit, is right on the money for that spec. engine, with a good torque curve.

[SweetBadger 94]

Cheers for the comments, good to hear that it fits in with what others have seen with similar specs. Giles, I'll be interested in seeing how your engine gets on in the new year.

 

It does drive well, although it's a bit off / on at low speeds with the throttle bodies - reminds me a little of how it used to drive way back when it had the original 1.6 engine with jetronic! Plus the lotus bodies have a nasty habit of the butterflies twisting slightly when they get hot, so I need to get a stiffer spring on the left hand bodies so that the ecu reads zero throttle properly (when they're hot you have to snap the throttle shut to get it back to idle).

 

I ended up in the Rotherhithe tunnel under the Thames on the way home from getting it mapped and the soundtrack was great!

 

It has got me thinking about noise limits on track-days though - any experience with MIs on bodies and whether they sneak in under the drive by noise limits? I go to Bedford quite often and I think their drive by limit is 87db so might be pushing my luck there with just a ITG filter and no air box?

[petert 586]

87dB is tough. Fairly sure mine is over the limit. JeffR on here was banned for being over the limit with his 405 and had to remake the filter housing. His thread:

http://forum.205gtidrivers.com/index.php?showtopic=143279