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| The late model head bolts are stronger and have a higher torque for a harder clamping load. |
We used the head bolts and main girdle bolts from a 2007 and later QR25DE as they are stronger and have a higher torque. We also used the intake manifold from a Rogue. The Rogue manifold has a larger plenum than the old style intake manifold. It is made of plastic so we are a little worried about how it will hold up to boost but we will try it. We had to slightly modify the head mating surface as the bolt pattern is slightly different.
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| The late model main girdle bed plate bolts were also used, these are stronger as well. |
When the engine went together we replaced the heavy front pulley with a lightweight billet aluminum one from Unorthodox Racing which takes about 3 lbs of rotating weight off of the front of the engine. We also used an idler pulley and bracket from a non air conditioned 2003 and later Altima so we could eliminate the air conditioning in a sano way.
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| The Unorthodox Racing pulley is machined out of billet aluminum and is 3 lbs lighter than the heavy stock steel part. |
Since the long stroke QR25DE does not like high rpm, we have chosen to limit its maximum revs to 7000 rpm and make power by adding turbo boost. In our experience, it is difficult to get front wheel drive cars with more than 350 wheel hp to be able to use the power without excessive wheel spin under road racing conditions. In a front wheel drive car, lots of wheelspin quickly overheats the front tires and leads to severe understeer, a condition to be avoided at all costs. To win will take a lot of horsepower. We are going to target 500 whp with boost mapping to keep wheelspin down in the lower gears.
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| An idler pulley from an Altima without air conditioning allowed us to remove the air conditioner compressor. |
After these mods, most of which were designed to help reliability, our attention is now turned to the turbo system. Stay tuned, for our next installment.
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