Anyone installed SC Power's stepper motor restrictor?

[900T-R]

After cleaning my stepper motor (which was a bit slow to react on coastdown, inducing the odd stall) the rpm tend to hang at around 2000 rpm when coasting down every once in a while. Resetting the grub screw on the plenum didn't completely eleminate the problem, so I bought the restrictor kit shown here (painless ordering procedure & prompt delivery BTW - thanks David!) http://www.sc-power.co.uk/SC%20Power%20Engine%20Mo... first item after plenum spacer/bell mouth trumpets.

It comes with a length of straight silicone hose, presumably to replace the one coming from the plenum into the stepper motor that has a couple of kinks and bends in it to clear the throttle spindle et al - and I have trouble deciding how the straight hose should be routed in order not to foul anything. Any ideas/experience?

[stefan1200]

I didn't bother with a kit, I cut the original hose at an appropriate position, took a 20 mm length piece of round plastic with an 8 mm hole which I then used to connect both ends of the hose again. Started with 6 mm hole, however this was too small for cold starts so I drilled it out to 8 mm which is just fine for 1200 rpm on rollout, dropping to 950 after stopping.

Stefan

[trackcar]

I use a radiator bleed valve from wickes / b+q etc .. gives you an adjustable bleed valve and sits neatly into the right angle turn as the pipe comes down from the stepper to the throttle spindle. just turn the bleed valve to give you the desired airlfow and lock it off with some thread lock or silicone sealer. Nice to see sc power making something easy to fit if you dont want to go to the trouble of playing with something adjutable though

Edited by trackcar on Sunday 14th December 14:57

[GreenV8S]

Dunno, I would have thought you just shove the restrictor into the existing hose from the stepper motor end and if it's not a tight fit use a hose clamp to pull the hose down onto it. I suppose you could always ask the people who supplied it?

[TVR Horsepower]

I had the same problem,the rpm tended to hang at around 1800 rpm when coasting down every time. I made my own 8mm restrictor and fitted it in the said hose. Works a treat only slight prob is it starts at 600rpm but within a few sec ups to 1200rpm then slowy drops to 900rpm as it warms. Sorted.....

[f@-pots]

Stepper motors are a bit like tonsils , if they do the job they're supposed to do all well and good,But if they start to give you hassle 'WHIP EM OUT !!' Or disconnect them when they have achieved a good tickover. Mine will tickover ok at about 50 degrees on the temp gaugue so only about a minute or so ,I've had it like that for about a couple of thousand miles and so far no prob's.
Just an idea though, each to his(or her) own.:

Nick.................

[900T-R]

Right, quick call to David & Colin at SC Power confirmed that the silicone hose would sit neatly and clear any moving parts of the throttle assembly quite happily when routed under the bracket - which it did. Start up & idle from stone cold unaffected. Happy chappy here.

Edited by 900T-R on Monday 15th December 18:09

[im]

GreenV8S said:

Dunno, I would have thought you just shove the restrictor into the existing hose from the stepper motor end and if it's not a tight fit use a hose clamp to pull the hose down onto it. I suppose you could always ask the people who supplied it?

They used my car as a guide for sizing the holes diameter in the resistor as I was having the high idle problem and well known TVR mapper hadn't been able to "map it out".

The restrictor works fine.

[900T-R]

Thought I'd return with some quick feedback - on my engine at least, this seems to be a perfectly judged modification. Car went from 'almost perfectly behaved' to perfectly behaved, period. Well chuffed.