SpeedCrazy Posted July 4, 2016 Report Share Posted July 4, 2016 My Shelby don't have 22000 miles on at. I have started to do some pulley changes. I put a 15% crank pulley and a 2.70 and Metco aux and cai and took cats off. Took it to the dyno and the supercharger is doing crazy things. When dyno 4 gear pull supercharger builds boost then around 4000 rpm to 5500 starts drops to 13 pounds then goes back up 5300 rpm to 5400 rpm 16 then drops again. I'm thinking slipping. So I change the top pulley back to the stock pulley a new green belt and it does it again but the rpms moves now it 4000 to 5200 and goes back up builds boost then drops again. At prodyno Dan were its been dyno at is trying to help. I'm taking off the 15% this morning and putting the stock pulley back on and putting a 2.60 on this morning and going back to the dyno in the morning. Can somebody help. I about sure It's not slipping the belt. Dan is thinking the bypass. Link to comment Share on other sites More sharing options...
speedrx Posted July 4, 2016 Report Share Posted July 4, 2016 Did you get a tune with the upgrades or is it still running stock tune? Making these changes (CAI, pulley, exhaust, etc.) requires reprogramming. Link to comment Share on other sites More sharing options...
SpeedCrazy Posted July 4, 2016 Author Report Share Posted July 4, 2016 Tune Link to comment Share on other sites More sharing options...
SpeedCrazy Posted July 4, 2016 Author Report Share Posted July 4, 2016 Yes got tune. I'm using the sct x4 Link to comment Share on other sites More sharing options...
SpeedCrazy Posted July 4, 2016 Author Report Share Posted July 4, 2016 I have change my mine and going to put the 2.70 pulley back on and go tomorrow. I don't have any slipping problem. No belt dust. Link to comment Share on other sites More sharing options...
SpeedCrazy Posted July 4, 2016 Author Report Share Posted July 4, 2016 The 15% is key way so it can't slip and I wouldnt think the stock would slip. So I'm going to try the 2.70 with a new belt. Link to comment Share on other sites More sharing options...
SpeedCrazy Posted July 4, 2016 Author Report Share Posted July 4, 2016 I did pull the plug and they looked good checked the gap 7 of them were 44 one was 42. I move them to 38. Link to comment Share on other sites More sharing options...
Secondo Posted July 4, 2016 Report Share Posted July 4, 2016 I did pull the plug and they looked good checked the gap 7 of them were 44 one was 42. I move them to 38. Wow, they should be .030 h .032 due to the higher boost. Link to comment Share on other sites More sharing options...
Ford Fest Posted July 5, 2016 Report Share Posted July 5, 2016 Wow, they should be .030 h .032 due to the higher boost. This I would reachout to VMP or Revan Racing before testing again Link to comment Share on other sites More sharing options...
msb64 Posted July 5, 2016 Report Share Posted July 5, 2016 That combo should get you around 17lbs of boost, which is fairly significant. Secondo is right on, you need to reduce the gap on them at those boost levels. As per the VMP thread, the recommended plug gap is .032 for up to 15psi, .028 for 16-19 psi and .026 for 20+ psi. You should drop them to .028, and Ford Fest's recommendation would be a smart move. Link to comment Share on other sites More sharing options...
Secondo Posted July 5, 2016 Report Share Posted July 5, 2016 +1 even smaller gap .028 because of the 15% lower pulley. Link to comment Share on other sites More sharing options...
SpeedCrazy Posted July 5, 2016 Author Report Share Posted July 5, 2016 Wow !!!! Link to comment Share on other sites More sharing options...
SpeedCrazy Posted July 5, 2016 Author Report Share Posted July 5, 2016 I just got back from the dyno I gap the plugs to 32 late last night. That fixed the up down boost problem. But it wouldn't pull about 15.53 boost and the next time it pulled 14.35 Do I need to drop the gap down to 30 or 28. I'm going to pick up some new plugs what is the best denso nkg the plug in it now is Motorcraft platinum Link to comment Share on other sites More sharing options...
msb64 Posted July 6, 2016 Report Share Posted July 6, 2016 Short version, Motorcraft SP-471 AGSF12FM1 plugs are a good choice, they are one step colder than stock and you should gap them to .028. Some good reading on the subject is here: http://www.fordgt500.com/forums/64-vmp-performance/134690-spark-plugs-101-a.html I am running the Motorcraft 1 step colder plugs, gapped at .028, a 2.6" upper pulley and an ATI 10% over lower\dampener. I also stepped up to the FFRP 56lb injectors and am running dual VMP pump boosters, even so I am at the upper limit of those injectors. Link to comment Share on other sites More sharing options...
SpeedCrazy Posted July 6, 2016 Author Report Share Posted July 6, 2016 Thanks that is good information. Link to comment Share on other sites More sharing options...
SpeedCrazy Posted July 12, 2016 Author Report Share Posted July 12, 2016 Put the new plugs in and gap to 28 seem a lot better Link to comment Share on other sites More sharing options...
mavisky Posted July 12, 2016 Report Share Posted July 12, 2016 What are you using for a tensioner to make up for the belt slack? Link to comment Share on other sites More sharing options...
SpeedCrazy Posted July 13, 2016 Author Report Share Posted July 13, 2016 New belts and the Metco aux Link to comment Share on other sites More sharing options...
Secondo Posted July 13, 2016 Report Share Posted July 13, 2016 New belts and the Metco aux And the tensioner? Link to comment Share on other sites More sharing options...
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