Thread: 351W dyno rwhp
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Old 07-06-2012, 08:30 AM
tirod tirod is offline
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Just because no one else mentioned it -

170 heads on a 351? The consensus I get lately is minimum 185 -195 would pull another 35hp and leave the curve up against the rpm limiter. On the bottom end, it would still be able to keep the same hp and begin building sooner.

HP is a tricky game, we see a lot of magazine dyno tests where they claim gobs of additional hp, but what really happened right there in the charts is it was robbed from the lower end, and the engine is just more peaky. Since MOST of the engine rpm is less than 5,000 rpm, I'm no fan of making the engine weaker where it will be used the most. I've gotten a bit cynical when I read one of these churned and spun stories selling some new parts.

On the other hand, plenty of tests show the newer bigger heads aren't killing the low end, which is why they are worth the money. If you see increases starting at 1,800 rpm, then something right is happening.

Another factor is the LCA of the cam, and whether it's appropriate for the intake. This seems to be another of those finesse points finally coming up to the surface, and a lot of the discussion is about getting that detail of cam timing right to match what you run - not just taking whatever it ships with. People are talking improvements measured in multiple tens of horsepower, so it's significant. Sure, on a 300hp motor that might be just a 5-8% improvement - or another way of looking at it, up to 25 hp.

Add three or four of those little finesse points, and it adds up quick.
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