The Imp Site


Date: Fri, 7 Aug 1998 08:07:03 +0100 (WET DST)
Subject: Re: Love my imp do i !!

> I'm very interested in hearing details of you turbo conversion. What
> modifications were necessary?

well i lowered the compression ratio to 8:1 which was a bit low really for road use . fine for racing ... there was no torque until the turbo boost came up about 3000 rev/min ..
a big oil cooler too ...
crank tuftrided , never wears .. extended oil pump for greater capacity ..

> Do you feel that it is a more reliable/
> cheaper/ easier/ powerful way to go than modifying a naturally aspirated
> engine?

More economical , lots more mid range torque , quieter smoother the Sport Camshaft is used .
a normally tuned engine would go well of course , but you wouldn't have the economy or the quietness ..

> I read in a old Cars and Car Conversions mag that the bearings in an Imp
> engine were 'squashed' when they reached an output of 130hp. Can the
> block (what mk?) withstand 170hp?! Sounds interesting...

Yes ! the block is a normal MK II with a strengthening plate .. Powermax bearings are holding up .. the Imp Crank bearings are quite generous if you compare them to some of the low friction modern engines today ..
Some Finnish racers have used 180 bhp turbo imps !
No idea how long they last though .
My turbo is not flat out all the time , so lasts well ,

I am currently building a new version with different L4 head and 930 type block modded to 998 cc and 9.5:1 compression ratio , this should give greater mid range torque , with possibly less top end power ..

Nick ...

Date: Fri, 7 Aug 1998 09:41:38 +0100 (WET DST)
From: Dave Edge
Subject: Turbo My Stiletto

I am very interested in turbocharging my engine, I learnt to drive in a turbo diesel Citroen BX (Very similar engine design in the petrol versions to an imp) and find the driving more challenging than a normally aspirated engine. I am interested in pulling more power out of my engine without going bigger than 930cc so I would like to fit a mild turbo.

There seem to be three routes

Who knows what if any turbo will fit with least mods, I am due to spend the week with my parents where there are extensive engineering facilities, I just need to know the appropriate unit to butcher!

It seems a fairly archane idea but would it be easier to supercharge an imp engine, I would imagine that supercharging would release far more power from an imp engine than any front engined car given the lack of air pressure normally.

Make new rear side windows out of perspex and fit large ducting down into the engine bay and into the air filter unit. Then fit some kind of (removable!) air intake onto the window, the advantage of this being that if it works, I can duplicate it on the other side to naturally aid my electric fan.

Date: Fri, 7 Aug 1998 10:38:15 +0100 (WET DST)
From: Graham Miller
Subject: RE: Turbo My Stiletto

As regards option c, some time back I noticed that the vents from the back of a Nissan Bluebird would fit in an Imp between the wheelarch and the door pillar. I always considered turning them round so that they forced air into the engine cavity by the carbs and the radiator, but you get problems with air pressure and speed not being constant relative to engine speed. Also I'm not sure if you'd mess up the aerodynamics but you could try putting a sport engine lid on with the louvres.