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can someone give me a honest answer on if its better to buy a brand new 604 or buy a fastrak rebuilt 604 ??? im wanting to know how much power- torque do you guys see from stock to rebuilt i have heard both ways some guys say there is difference from night to day in a rebuitl one???
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i have heard of people buying a new 604 dynoing it and getting right at the 400-410hp mark then take it in to be "blue printed" and they squeeze 450 or more out of it will all OEM parts, but matched with tighter tolerances.
with that in mind pay attention to your rules, we are NOT fastrak sancitoned and our track requires us to have the original seal bolts, otherwise anything rebuilt has to have 40lbs in front of the motor plate with 20 on each side. another thing our track has done in the past is take motors once in a while from the top guys and run them on a dyno then tear them down and if they are more than 15hp out of tolerance from what the OEM dyno sheet was they keep your motor. If you are found legal, they give you and brand new motor to replace what you had(i think they gave away 3 or 4 motors doing this)
this year they are introducing a new rule that has something to do about the track swapping peoples motors, not sure how that is going to fly, but i guess we will see what happens. -
Just to let you know there is 30-40HP just in matching your carb and ignition system to the fuel you are running and that is 100% legal. I have been doing acceleration testing on my chassis dyno since for almost 20 years. Seems as though Circle-Track and others think it is something new???
There is no match out there to getting your carb and ignition matched to the burn curve of the fuel you are running along with the proper acceleration rate of the engine. That HP increase relates to an acceleration factor of .3-.4 sec on a 7 second dyno pull.
I have done back to back testing on a couple customer cars, 604 engine builders as well as getting data back from folks that have run the stuff on ChassisDYno's at their place. Results are pretty close to almost 1 sec per lap on the track.
Same thing works for 602 and makes a bigger impact there as they start off with a lot less out of a pretty decent engine package.Comment
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