My 390 Dyno Run and Tune :D

[maston]

Just thought I'd share this, chuffed with the results.
The red line is after the ignition timing was adjusted to 21 degrees.
I have since installed a silicone AFM to Plenum hose so the throttle response is now better even still
Next on the list possibly are flared trumpets ???


Max bhp was 227
Max Torque 254 ftlb.

Edited by maston on Thursday 1st August 19:20

[adam quantrill]

Hi Ian - is that 21deg BTDC?

Why do you think you have to have it so high - is the mechanical advance not advancing very much?

If you take a look at the low end you've lost about as much torque as you gained at the top. My 350i was like this when I got it and it turned out that the advance mechanism was seized, so the low end bogged down a bit. The previous owner of dealer had advanced the dizzy quite a lot to compensate. Replacing with a spare dizzy opened up the rev range top and bottom.

[mrzigazaga]

Hi Ian..Not bad figures mate..Good torque..Im hoping to squeeze some more out of mine soon..Bit of advice though mate..Try and get that header fixed..Please..Sell the onion and garlic muncher and concerntrate on the wedge..You have a good car there that just needs some TLC...Seriously mate if your wise with around 3K you could have most of it sorted including the bonnet stay fitting re-glassed and possibly a blow over..Bonnet struts..New silicone hoses..A boot that locks..Doors that lock and un-lock properly..Manifold sorted..New petrol lines from tanks onwards..Cleaned interior and refreshed vinyl/Leather..Working headlights..Wipers that dont fly off..And whatever else is on that list!..As an incentive if you do i will come over and bling up some under bonnet alloy....."Hello Mr Bling bling".."Yes...I see..Ok..See you then..Oh my fee is cups of tea and a bacon sarnie..Thank you...Goodbye"....

[maston]

Cheers Mark, yes, all noted mate. Thank you for your offer too mate

Adam, if it makes more sense then I know it has a piper camshaft that coincidently kicks in at around 3500rpm just when the torque is on the decline ?????
Regarding the advance, do you think there is a problem ???
The first run (18 degrees BTDC) produced 220, the second run (25 degrees BTDC) produced 184 ??? (the tuner was a bit baffled, I guess the markings on the dizzy are wrong ???) and the final run (21 degrees BTDC) produced 227 ???
Any further help/advice appreciated.
PS If it matters I have a Mallory electronic dizzy set up ?????????
Many Thanks
Regards
Ian

[adam quantrill]

Ahh yes maybe the cam means it needs more advance overall.

However at low revs it obviously needs less advance (because when you had less advance - you had more torque). THis effect may be because of the cam too and it might get even more pronounced when the revs are around 1000-1500.

So maybe you could get a small improvement if you had more of a mechanical advance range - around 2 or 3 degrees extra and back off the timing at idle would give you back extra torque low down too.

Just a thought though if you want to make the most of it, you are getting good power as it is.

I don't know how you go about fiddling with the dizzy advance weights to get this effect (without breaking it) but maybe there are people on here who have done it?

[mrzigazaga]

Adam...I know this is good sound advice but in all fairness and i mean this in a kind sincere way..Ian is unfortunately a serial car fiddler..He is also a very nice dude with a heart of gold but he cant resist a fiddle..bless him..In the world of batman there is the "Riddler"...In the world of wedge there is the "Fiddler"..The only difference is that there is batman to stop the riddler..There is no man or beast that can stop the fiddler..Please dont give him reason to get out the screwdriver...FFS!!!...

Ian..You know i mean this in a respectful manner...And i class you as a good friend so i must say be happy with the power figures that you have as they are not bad at all...Concerntrate on other issues with the 390..Hopefully this time next year you will have one well sorted rare beastie..And an even bigger grin on your mooey... ..Speak soon mate...Cheers...Ziga

[Rockettvr]

Here's some inspiration for you Ian http://www.pistonheads.com/classifieds/used-cars/t... A little TLC and yours could be like this.... Cheap for a 390 don't you think ?

[Wedg1e]

Ian, did you get an air:fuel ratio curve to go with the power/torque figures?

I'm surprised that there aren't more than 227 ponies trying to break free...

[maston]

Wedg1e said:

Ian, did you get an air:fuel ratio curve to go with the power/torque figures?

I'm surprised that there aren't more than 227 ponies trying to break free...

Ian, no I didn't I'm afraid. Although straight after the initial run the tuner said "blimey, perfect air/fuel ratio so no worries there". Chris who was with me will back me up on that.
To be honest, given that TVR way way over exaggerated the claimed "275bhp" for a 390 (a marketing ploy and if I understand correctly they way over exaggerated nearly all TVR's claimed bhp's and specifically wedges ie a typical 350i should have about 160bhp rather than the claimed "195 bhp") and also the fact that the engine is 27 years old I am more than happy with 227 ponies. I really thought that the power would be around the 200 mark so naturally I was quite chuffed. I suppose I may have another 1 or 2 now that I have installed a silicone hose between the afm and plenum
Out of interest have you had your 390 on the rolling road and if so what were the results ?

PS You're more than welcome to come round and let the extra ponies escape

[Wedg1e]

maston said:

Out of interest have you had your 390 on the rolling road and if so what were the results ?

PS You're more than welcome to come round and let the extra ponies escape

Yes, at BBWF a couple of years ago my car was showing 256bhp and 280 lb.ft. running on 95RON Tesco unleaded. Granted it's a 3948cc engine, rebored from its original 3905, but it runs lower-compression pistons so it's more or less a 400SE engine running the 390's injection... or it would be if it was fitted. The NCK inlet manifold was replaced by a spare set-up on which I'd done some mild porting work so it's nothing like as drastic as the NCK manifold (some folk have said the NCK unit is actually over-ported).
It also has some mildly uprated injectors running at lower fuel rail pressure than standard. Other than that the ignition system is standard Lucas 35DLM8 distributor and ignition amp; I have no idea what the advance is as I jut twiddled until it seemed about right
On the day it was within a whisker of a 400SE running hotwire/ mapped injection, coil packs etc. (and I mean about 1bhp and half a lb.ft different)... highest on the day was over 330bhp but that was a 4.6L I think.
Don't get me wrong, I'm not saying your results are poor but I'm sure you could improve on your figure; 220 to 240 bhp is the usual for a fit 400SE but the higher compression, ported heads etc. of the 3905 motor should give you an edge.

Here's some of the work I did to my injection...

http://www.wedgeneering.co.uk/TVR%20390SE%20p3.htm