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My concerns is with the rod bolts ... JWT will tell you that this is the weak point in a race motor above ~7800rpm
If I was running to 8000rpm on a track I'd life the rod-bolts to 40 hours. |
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Then you have to worry about the crank and oil pump. The motors JWT prepared were dry sumped due to this issue and had Bryant cranks. It's not just the valve float you have to worry about.
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Suckerpunch alone claims their pump set-up is race proven up to 8600. |
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Doren Racing was changing the OEM crank after every race because of breakage. It took them 2 years for them to have the rules changed to run a billet crank. Broken cranks have cost them some race wins. The OEM crank is not good for over 8K for racing.
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Good memory - I remember Doran was having problems. But even after the rules were changed I thought they were still running into issues at times. Couldn't remember all the details :tiphat:
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I'm not looking for trade secrets but generalized information without ambiguity or apparent speculation is more helpful to the community I would imagine. Helping a common guy plan a build is often vastly different then a race team trying to get their car ready for a season. The whole point of this forum, I thought, was for the common enthusiasts to share information and grow. I know more vetted members can get frustrated with what may seem like ridiculous new blood questions but it's sharing information like what was learned from race teams and from our own experience that can help everyone grow; at least that's my thoughts and experience from being apart of these types of forums over the years.
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I had my 370Z at 7900 rpm and had no issues beating on it for over a year. I needed the extra rpm as it really helps in 1/4 mile time, but other than that there's no reason to go higher on a car that's just a daily.
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I have my redline set at 8,000. My shift light at 7,500. I shift at 7,500. The only time I hit 8,000 is at the end of the straight to save an up shift, down shift condition.
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The data is not always out there sometimes. Sometimes you have to wear on people's nerves to get information that they themselves might think is out there. |
Mate, I have been involved in motorsport for over 40 years, and I learned a long time ago that "engineering" solutions to avoid problems is a lot cheaper than engine rebuilds.
You are talking to a guy who broke 3 engines in a single season back in the 80's and they were 8-10k each in $'s of the day - maybe 2.5 times that now. IMHO, it is well worth investing in components to eliminate sources of failure and lifing components appropriately. That said - this is feedback from a hard-core racer - and for anyone beating on rtheir daily for 15 seconds at a time - maybe you can ignore it. If you are regularly tracking your car and it spends more than 20 seconds per minute at WoT, then maybe you can benefit from my experience. Doran racing and JWT (their engine builders) will both tell you that OEM cranks crack quickly at 8000+rpm and rod-bolts are a weak point in the OEM engine - do they fail - no, BUT if there is a crack - it will fail in an unpredictable time. The engineers solution is to change it once a crack shows I'm more than happy to be ignored - but feel bound to put my hard-won knowledge out there if it can help others which I think is the purpsoe of a forum like this one. Happy for the dissenters to dissent but am perfectly comfortable with my views. |
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