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Anders Dinsen
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YaBB God
Posts: 3188
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« Reply #19 on: January 21, 2008, 10:16:56 pm » |
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Yes, seems like turbo has potensiale, but also lots of work... Anders, how many hours work will it be to change the cam? How about changing carbs? from what i could tell, converting to injection doesnt give any boost in hp.
Sidedraughths (Weber or Dellorto's) won't give you much on the torque, but should give you something on the top - but is that what you need? I wouldn't start tuning on the standard cam, however. It's only 256 degrees period (inlet) so if you want increased volumetric efficiency (i.e. power/litre) with that, I think you will need to blow the air into the cylinder using a super charger or turbo. The S-cam has 279 degrees of inlet period. That's a decent tuning cam, but the Holbay is up to 296 and 76 degrees of overlap. This cam should have a lot of potential, but seen from the point of view of the DIY tuner on a budget, it's an excellent choice because it runs so well on the unmodified engine. Idle is rough of course, but not badly, and it works well even on the standard induction (single carb and standard manifold) and on an unported head. The exhaust is probably more important, as the rapidly moving exhaust gasses help start the induction early due to the overlap. A camshaft tuning book I have says that 290+ degrees are chosen when mid-range power is needed, which is just what we want on a road going Murena - and I can confirm that it does enhance the mid-range. The engine runs smoothly, but not aggressively at 1500-2500 rpm, but from 3000 it really starts to work, and at 3500 it's *very* torquey and revs freely past 6000+ rpm. If I need a really fast start, I have to rev it up to 4500 in 1st. Remember the Murena has a lot of weight on the rear wheels, and the grip will rapidly increase with acceleration - so it's just very difficult to spin the wheels. This is nothing like your daily front wheel driver!! Most of the time, however, I enjoy an easy start in 1st, but floor it when it reaches 3000 rpm in 2nd. The sound and acceleration usually causes my smile to extend all the way to my ears! Porting/changing inlet/oulet manifold without changing cam, does that improve anything?
Probably not, no. Too much winding roads if you ask me..... At least in the Opel stationwagon....
I have ONE thing to say: When you buy the Murena you will start LOVING the winding roads! Even those with speed limits. There's just SO much fun in that car.
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« Last Edit: January 21, 2008, 10:19:00 pm by Anders Dinsen »
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1982 Talbot Matra Murena 2.2 prep 142 2017 BMW i3 "Charged Professional" 94Ah
Used to own: 2001 Renault Matra Grand Espace "The Race" V6 24v 1997 Renault Matra Espace 2.0 8V 1987 Renault Matra Espace J11 2.2
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