thanks Timmy,
the curve is unknown....
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| Dynotune tomorrow https://www.ausmini.com/forums/viewtopic.php?f=2&t=93400 |
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| Author: | deluxe67 [ Tue Aug 09, 2016 7:22 pm ] |
| Post subject: | Dynotune tomorrow |
Hi all, Tomorrow the restoration project climaxes with a dynotune at a Mini friendly garage in Moorabbin, Melbourne. If people have any pearls of wisdom to offer I'd much appreciate it, it's a first for me. Specs of the car are as follows... 1967 Mini De Luxe albeit a bit souped up. 1293cc with 45mm Weber (34mm chokes fitted at the moment but have 38mm chokes spare if useful?) and LCB extractors and free flow sports muffler. 11:1 compression ratio, seriously modified cylinder head. The head was put together (lot of money spent 15? years ago) with the brief "build me a race head". It sat at the bottom of my waldrobe until about 5000km ago so it's basically fresh. Its been cruising from Melbourne to Bali via East Timor and thats all... The distributor is standard Cooper S with points. Dry suspension with all the good bits (as when I bought it) and the gearbox is custom made with close ratios. The car has disc brakes. The camshaft is the same as the one the Doctor has in his car, the Russell Engineering RE 282 (Hi Doc, your description of the camshaft convinced me..). The car goes well now but has never been tuned other than my efforts. It does not detonate or overheat (got one of those Chinese alloy radiators which has been great, the car didn't come close to overheating in 2 years in the tropics...). On paper, I'm thinking the car should have the potential to be a seriously quick car but I would very much appreciate any advice on how it should be tuned or if there are things I need to consider. Thanks very much, Michael |
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| Author: | timmy201 [ Tue Aug 09, 2016 8:23 pm ] |
| Post subject: | Re: Dynotune tomorrow |
All sounds pretty good. Only thing I'd think about is the distributor. Who knows how well a standard 50 year old distributor curve will be matched to modern fuel and your engine modifications? |
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| Author: | deluxe67 [ Tue Aug 09, 2016 8:29 pm ] |
| Post subject: | Re: Dynotune tomorrow |
thanks Timmy, the curve is unknown....
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| Author: | gtogreen1969 [ Tue Aug 09, 2016 8:50 pm ] |
| Post subject: | Re: Dynotune tomorrow |
This is supposed to be the Cooper S advance curve. A very slow curve. The experts say the max advance should be all done by 3000-3500 rpm on a worked engine. Engine rpm = Deg BTDC 650 rpm = 0 - 2 deg 830 rpm = 4 - 8 deg 1000 rpm = 8 - 12 deg 4000 rpm = 18 - 22 deg 7000 rpm = 28 - 32 deg |
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| Author: | deluxe67 [ Tue Aug 09, 2016 9:02 pm ] |
| Post subject: | Re: Dynotune tomorrow |
thanks gtgreen, very useful info, sure in will come in handy.. |
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| Author: | drmini in aust [ Tue Aug 09, 2016 10:22 pm ] |
| Post subject: | Re: Dynotune tomorrow |
IMO, 34 chokes will be too small for good power, and the 38s too big for drivability. 36s are the sweet spot. I had 34s and then 38s in my 45 Dellorto, have been using 36s for 4 years now, they are just right. |
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| Author: | gtogreen1969 [ Wed Aug 10, 2016 5:51 pm ] |
| Post subject: | Re: Dynotune tomorrow |
Did you crack 80hp? |
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| Author: | deluxe67 [ Thu Aug 11, 2016 10:18 am ] |
| Post subject: | Re: Dynotune tomorrow |
Didn't get a meaningful figure for power output, the dyno produced just a number that I guess is relative to power and that's it. Adjustments were made to ensure the fuel/ air ratio was correct throughout the rev range and the power output number was maximised. i.e. there wasn't a calibrated/ precise figure for the output. Is this typical of dyno's/ dyno tuning? This was my 1st experience so I don't know. Hearing the engine "screaming" at 7000 rpm was painful and not an enjoyable experience.... |
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| Author: | deluxe67 [ Thu Aug 11, 2016 2:42 pm ] |
| Post subject: | Re: Dynotune tomorrow |
Update... Went to drive the car today and it was undrivable. Backfiring and farting all over the place. Took it back to the tuner to have another go. Depressingly his comments are all negative. He is convinced something is wrong and is skeptical good results are not possible with the car as it's set up. "Running like a bag of crap" is the technical term. He cannot get a satisfactory idle, his comment being it idles on 2 1/2 cylinders. Disconnecting plug leads 1 and 4 in turn have minimal effect on idle speed. He also believes it's low on power for the engine specs. The camshaft is correctly set up, though 135 psi cylinder pressures (all the same) doesn't seem right for a 11:1 comp. ratio cylinder head. He believes the carburettor/ manifold/ camshaft combination fundamentally "is not working" and is not behaving at all like a cammy engine. This I know can't be typical because other people have good results with this setup and similar cam/ weber setups have been used with success on Mini's since the year dot. He wants me to toss the Weber and source a set of twin SU's and get the dizzy curve regraphed to give 12 degrees static at idle with 30 total @ 3500. To say I'm despondent is an understatement. I don't know what I should do from here. To date I've only gone backwards, at expense Your comments/ advice/ suggestions is much appreciated, I'm all ears. Is it possible I have a dog of an engine or could there be a fundamental screwup somewhere? The basics seem to be all there. Fuel/air ratios correct throughout the rev range, camshaft setup checks out, cylinder head checks out. Doc, are you able to tell me what compression pressures you are getting with your RE282 setup? I thought 135 psi is lowish but due to the large valve overlap? Help! |
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| Author: | winabbey [ Thu Aug 11, 2016 3:18 pm ] |
| Post subject: | Re: Dynotune tomorrow |
Maybe get some advice from David Walker at Link Automotive, Mitcham. |
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| Author: | gtogreen1969 [ Thu Aug 11, 2016 3:19 pm ] |
| Post subject: | Re: Dynotune tomorrow |
Can you confirm the procedure used for testing the compression. Warm engine, all spark plugs out, throttle wide open, battery fully charged, turn over for approx 8 to 10 seconds or until the pressure stops rising. Yes you can get lower compression using a large overlap cam. If there is less than 5% difference between the cylinders then i wouldnt be worried about the 135psi with a big cam. |
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| Author: | deluxe67 [ Thu Aug 11, 2016 5:57 pm ] |
| Post subject: | Re: Dynotune tomorrow |
Engine was warm, wide open throttle, all 135 psi.. |
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| Author: | gtogreen1969 [ Thu Aug 11, 2016 6:07 pm ] |
| Post subject: | Re: Dynotune tomorrow |
You would hope that having a dynotune the car would come back better then when it started. What were the readings from the sniffer? |
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| Author: | deluxe67 [ Thu Aug 11, 2016 6:18 pm ] |
| Post subject: | Re: Dynotune tomorrow |
The sniffer said fuel/ air ratios were correct from idle to 7000 rpm... |
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| Author: | slide [ Thu Aug 11, 2016 6:29 pm ] |
| Post subject: | Re: Dynotune tomorrow |
The car went ok before you took it in for a tune didn't it? Any vacuum leaks? On the ignition side are the plugs, leads, coil and points all 100% ok after the dyno work out? I doubt the advance curve would make a ton of difference, may make it sluggish until you get the timing spot on but not back fire and carry on as you describe. Surely a dyno operator should have all the right test equipment on site to identify precisely where the problem lays. |
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