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Old 07-14-2006, 06:43 PM   #11
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Sorry, my SSEi is a 2002, just trying to increase the value hehe. Mark L
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Old 07-14-2006, 08:43 PM   #12
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Quote:
Originally Posted by Dirthead Racing
I run modified 1.9'* with stock springs(231K miles...it'* a risk I know but at 231K miles everything is a risk ) and know of 3 other cars with the same setup without issues....but that is all the research I have done on it as well so take that statement with a grain of salt . I witnessed a 1mpg increase in fuel economy....but I changed pulley, ported things, and changed plugs all at that same time so I can't attest to just the 1.9'* increasing fuel economy. I would have to imagine going from a 3.8 to a 3.25 pulley negated a little of my fuel economy increase due to the parasitic loss of the supercharger.
Key word their... modified has more deflection.

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We spent a lot of time optimizing ratios and studying the market for rockers. Most people are in one of two categories. Those that don't want to change valve springs and those that do. We did extensive research to determine optimal ratios. We researched where valve float occurs with each ratio, what the difference there is between a used set of stock valve springs and a new set, and what RPM is optimal to spin your engine to vs. what rpm are people commonly running.

What we found is that even with stock shift points and the super light weight of our rockers, most people running higher mileage valve springs will still get valve float with our 1.9 ratio rockers. What we also discovered is that we could run very close to 1.9 if we kept the shift points stock (1.8. The problem is that there are gains to be had shifting higher. The second problem is that most people running rockers have an aftermarket PCM with raised shift points already. So to explain in basic terms: You are better off performance wise, running a 1.8 ratio with 6k shift points than you are running a 1.9 ratio with 5700rpm shift points.

Once we settled on an optimal shift point, we set out to pinpoint the optimum ratio roller rocker for use with stock valve springs. A ratio that would give the highest possible gains without the risk of valve float, even on higher mileage engines. We cam up with 1.84 and while this may seem a lot less than the 1.9'* you keep the benefits of the lower spring rate. That means less tensioner wear and slightly less rocker deflection.
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Old 07-15-2006, 04:24 PM   #13
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Anybody ever experience valves kissing after changing rockers yet? What type of pistons are used in our 3800 engines? What'* the stock ratio?
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Old 07-15-2006, 04:28 PM   #14
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Quote:
Originally Posted by Dirthead Racing
I would have to imagine going from a 3.8 to a 3.25 pulley negated a little of my fuel economy increase due to the parasitic loss of the supercharger.
The */C doesn't draw more power untill it is compressing the air & by the time is doing that your fuel economy is going to suffer reguardless.

The stock ratio is 1.60


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Old 07-15-2006, 08:21 PM   #15
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Old 07-16-2006, 12:27 PM   #16
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One last thought about a rocker swap. Did the bottom end torque suffer with the higher ratio rockers?
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Old 07-16-2006, 12:30 PM   #17
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It'* possible that it might if you only did the exhaust side, but you aren't. Your torque will increase, and I believe the peak RPM it'* delivered at may shift slightly higher, but not significantly. www.INTENSE-racing.com should have some dyno'* up to show this, or PM Rogue to this topic and he can provide some.
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