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This +5/-5 all started when one "respected" forum member tried it and next thing you know almost everybody takes it as fact. People have to realized every engine is different and you have to figure out the cam timing for yourself. Cam timing is like ignition timing, it's different for everybody.
This +5/-5 all started when one "respected" forum member tried it and next thing you know almost everybody takes it as fact. People have to realized every engine is different and you have to figure out the cam timing for yourself. Cam timing is like ignition timing, it's different for everybody.
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take her to a dyno and test see what is the best set up for ur motor
Well, that's a given, but if someone says that +5/-5 isn't best in their experience for best top end, I'd love to hear what WAS. Give me a starting point or target at least.
Anyone can say X/Y is no good - go dyno to find what is. Not helpful though.
Well, the trend is more top end when you start moving the intake back toward 0. Generally, a tight lobe separation angle/LSA will give you a short peaky power band and wider LSA will give you a wide power band, where the peak power will carry further into the 8,000 rpm area. For those who are running +5/-5 on the N1, you will notice your peak power usually drop off after 7,500 - 7,800 rpm. There are exceptions to this trend, but that's because these people either have a custom header or a custom intake manifold.
Another thing people should consider is the sr20ve is different from the sr20de when it comes to overlap. The DE can't get enough overlap but with the VE there's a limit. When you reach it, power will be down everywhere. The limit is somewhere the intake lift at tdc is .180" and the exhaust lift of .170" at tdc. For the people running +5 intake, you are pretty close to .180" at tdc.
My statement comes from first hand experimentations and observations, and not from reading things on the internet. So far I've tried 11 lobe center combinations for the Franklin S4, 3 combinations for N1 intake with FS4 Exhaust, and currently trying out N1 intake with sr16 exhaust.
If I'm not forthcoming with all the info, that's because I believe in a give and take relationship. I will share with those who share their info with and me, and are willing to experiment.
Well, the trend is more top end when you start moving the intake back toward 0. Generally, a tight lobe separation angle/LSA will give you a short peaky power band and wider LSA will give you a wide power band, where the peak power will carry further into the 8,000 rpm area. For those who are running +5/-5 on the N1, you will notice your peak power usually drop off after 7,500 - 7,800 rpm. There are exceptions to this trend, but that's because these people either have a custom header or a custom intake manifold.
Another thing people should consider is the sr20ve is different from the sr20de when it comes to overlap. The DE can't get enough overlap but with the VE there's a limit. When you reach it, power will be down everywhere. The limit is somewhere the intake lift at tdc is .180" and the exhaust lift of .170" at tdc. For the people running +5 intake, you are pretty close to .180" at tdc.
My statement comes from first hand experimentations and observations, and not from reading things on the internet. So far I've tried 11 lobe center combinations for the Franklin S4, 3 combinations for N1 intake with FS4 Exhaust, and currently trying out N1 intake with sr16 exhaust.
If I'm not forthcoming with all the info, that's because I believe in a give and take relationship. I will share with those who share their info with and me, and are willing to experiment.
WOW!
That kind of information is PRICELESS!
It's golden for those at that stage of tuning, and will help anyone on their quest for increasing performance in the VE.
TY for the info, it is EXTREMELY helpfull.
