CMF_Nissanmania
» CMF Member
This is the latest dyno run after changing from 4:2:1 manifold to 4:1 item from Impul.
Some explanatory notes first:
1. This dyno runs low so ignore absolute HP figures - can run 10-20% lower than other dynos. More interested in HP changes and the shape and area under the curve.
2. Previous dyno runs were in fourth gear which gave an abnormally low reading - just as the diameter of the wheels can change a reading etc. These runs are in 3rd gear which gives a more comparable output to other dynos.
My driving impressions of the new Impul 4:1 manifold - awesome! Doesn't look so dramatic on the chart but the dip at around 4000rpm with the old manifold has disappeared with a good solid gain all the way to 7000rpm where it dips (no amount of tuning changes this so probably a characteristic of the overall package). And it sounds fantastic too with an angry rasp as it barrels up the rev range (will post a video sometime soon). Was running lean through the whole map with the new manifold on so was obviously flowing alot better. There's probably a little more to be gained in the 4-7000rpm area with a bit more tuning. I'm not too worried about the fall off over 7000rpm as would only spend 5% of the time up there and not that noticeable. Likewise with the area between 2-3,000rpm. The significant gain is the increase in the area under the curve between 4000 and 7000rpm - the play zone!
A 4:1 manifold, especially with short primaries should theoretically work mainly in the upper rev range but this set up seems to offer a reasonably broad power band. I would add this motor has very aggressive high duration/lift Datrats sourced cams and quad throttles so would not expect the same results on a stockie.
Some explanatory notes first:
1. This dyno runs low so ignore absolute HP figures - can run 10-20% lower than other dynos. More interested in HP changes and the shape and area under the curve.
2. Previous dyno runs were in fourth gear which gave an abnormally low reading - just as the diameter of the wheels can change a reading etc. These runs are in 3rd gear which gives a more comparable output to other dynos.
My driving impressions of the new Impul 4:1 manifold - awesome! Doesn't look so dramatic on the chart but the dip at around 4000rpm with the old manifold has disappeared with a good solid gain all the way to 7000rpm where it dips (no amount of tuning changes this so probably a characteristic of the overall package). And it sounds fantastic too with an angry rasp as it barrels up the rev range (will post a video sometime soon). Was running lean through the whole map with the new manifold on so was obviously flowing alot better. There's probably a little more to be gained in the 4-7000rpm area with a bit more tuning. I'm not too worried about the fall off over 7000rpm as would only spend 5% of the time up there and not that noticeable. Likewise with the area between 2-3,000rpm. The significant gain is the increase in the area under the curve between 4000 and 7000rpm - the play zone!
A 4:1 manifold, especially with short primaries should theoretically work mainly in the upper rev range but this set up seems to offer a reasonably broad power band. I would add this motor has very aggressive high duration/lift Datrats sourced cams and quad throttles so would not expect the same results on a stockie.
