gmc 4-1 manifold or a 4-2-1?

1. air121005 Newbie Joined: Feb 2006 Bromsgrove United Kingdom (England) Posts: 20

   #1 4th December 2006, 23:21

   i have a gmc 4-1 manifold but want to know what would be a good 4-2-1 manifold to replace it with to get better torque output?
2. S34MER East Midlands Joined: Jun 2006 Derby Posts: 8305 Skoda Fabia VRS

   #2 4th December 2006, 23:23

   read this thread mate and you will find the answer!!
3. Sean Saxperience Post Whore Joined: Feb 2005 St Andrews United Kingdom (Scotland) Posts: 7384 Green mk1 vtr/s and Focus zetec

   #3 4th December 2006, 23:31

   would help if you said which model you had? although saying that i wouldn't bother swapping, i'd keep the gmc 4-1. the vtr has decent low down torque so the 4-1 would help it out mid-range and top end where the standard manifold is restrictive. on the vts the low down standard torque curve is quite similar to the vtr and with the vts the peak torque and power kicks in after 4k which again is where a 4-1 would increase it. no point increasing low down torque on the vts imo as how often do you go below 3-4k when driving quickly (which is after all why you fit 'performance' parts)
4. air121005 Newbie Joined: Feb 2006 Bromsgrove United Kingdom (England) Posts: 20

   #4 4th December 2006, 23:45

   sounds like i should stick with the gmc!
5. KamRacing Saxperience Addict Joined: Nov 2006 A farm shed in Aylesbury Posts: 14916 Corolla AE86 Peugeot 205 B18C (in bits)

   #5 5th December 2006, 05:53

   I would stick with what you have. You'd probably not notice so much of a difference between the two to make it worthwhile especially as i presume you are running standard cams
6. air121005 Newbie Joined: Feb 2006 Bromsgrove United Kingdom (England) Posts: 20

   #6 6th December 2006, 22:11

   Quote:

   Originally Posted by KamRacing I would stick with what you have. You'd probably not notice so much of a difference between the two to make it worthwhile especially as i presume you are running standard cams

   running a kent cam, timed vernier, up'd compression, up'd fuel pressure, ported.
   
   just wondered where would be poss to squeeze a tiny bit more from?!
7. air121005 Newbie Joined: Feb 2006 Bromsgrove United Kingdom (England) Posts: 20

   #7 6th December 2006, 22:14

   forgot to say, got a mk.1 vtr.
8. Sean Saxperience Post Whore Joined: Feb 2005 St Andrews United Kingdom (Scotland) Posts: 7384 Green mk1 vtr/s and Focus zetec

   #8 6th December 2006, 22:18

   you need the ecu remapped to get the best out of the cam, that should make it run better and also free up a few more horsepower.
9. KamRacing Saxperience Addict Joined: Nov 2006 A farm shed in Aylesbury Posts: 14916 Corolla AE86 Peugeot 205 B18C (in bits)

   #9 6th December 2006, 22:23

   Quote:

   Originally Posted by air121005 running a kent cam, timed vernier, up'd compression, up'd fuel pressure, ported. just wondered where would be poss to squeeze a tiny bit more from?!

   Whats the power band like on your current cams?
   
   Do you know the spec of them?
10. air121005 Newbie Joined: Feb 2006 Bromsgrove United Kingdom (England) Posts: 20

    #10 6th December 2006, 22:51

    kent pt11, spec from the kent catalogue is:
    276 duration
    timing 28/68 68/28
    power band 2000 - 6000
    
    low end torque has been greatly improved and acceleration is now a lot quicker!
    completely changed the car!
    tick over is smooth, was actually quite suprised it wasn't a lot lumpier being of 276 duration!
    
    very impressed with it to be honest!