How To Get 500+ More RPM, Without Changing Cam |
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How To Get 500+ More RPM, Without Changing Cam |
motorvated |
Jan 15 2019, 05:50 PM
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#1
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Member Group: Members Posts: 279 Joined: 13-February 13 From: Colorado Member No.: 15,519 Region Association: Rocky Mountains |
2.0 Liter Four. Doing a top end refresh and not planning on splitting the cases or changing the cam. Would stiffer valve springs and beefier pushrods get me there. I'm a little confused when looking at aftermarket springs, as the European Motorworks Single HD springs are rated at 135 psi seat pressure, and stock springs are rated at about 175 psi. Also thinking that chromoly pushrods set at zero clearance cold don't let the valves open fully when hot due to the lower expansion of the pushrod, plus they are a lot heavier than aluminum pushrods. So what can I use to get those elusive extra 500+ rpm? My old stock 1.8 floated valves up near 6,000, which wasn't bad, but I'd like a little more with the 2.0 liter. I'm racing the car in Vintage. Any suggestions.
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Mark Henry |
Jan 15 2019, 09:13 PM
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#2
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that's what I do! Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada |
Heavier springs also take horsepower to run.
I agree the cam is over it torque curve at 5400-5600 rpm. The T4 has design limitations, The heavy pushrod valve train is a lot to be pushing around at high rpms. The dual springs stops float when using high lift cams with aggressive ramps and a full balanced rotating assembly. Springs have a lot to do with cam choice, if you put dual springs on an otherwize stock motor you'd lose HP. When I build a performance T4 I really don't give a shit about the final HP number, it's the torque curve I'm looking at. Then you have to get that torque to the pavement. |
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