bfsnail Posted November 23, 2010 Share Posted November 23, 2010 I hate to be this guy, but I need some quick help or guidance. My head is at a machine shop and I'm kind of under the impression that I may need to replace my cam. My original plan was to keep the stock cam as I am only aiming for ~300hp, but since it may have to be replaced anyway, I am looking into a performance cam. I am under the impression right now that the stock cam becomes gutless around 4-5k rpm and I wouldnt mind an engine that was a slightly less street friendly and bumped the power band up to a higher rpm. Can anyone recommend a cam or grind that would get me what I'm looking for? Quote Link to comment Share on other sites More sharing options...
bfsnail Posted November 23, 2010 Author Share Posted November 23, 2010 Please confirm or deny... Duration is a huge player of where your powerband is. So if thats correct, a cam with a .460/.460 lift and 460/460 duration will push the power to higher rpms. Question is, is this a streetable configuration? The car is not going to be a daily driver, but it will pretty much be only driven on the street. Quote Link to comment Share on other sites More sharing options...
BLOZ UP Posted November 28, 2010 Share Posted November 28, 2010 460 duration? It's open more than 100% of the time? Quote Link to comment Share on other sites More sharing options...
Leon Posted November 29, 2010 Share Posted November 29, 2010 That cam would make negative horsepower, you'd have to push the car to move it. Quote Link to comment Share on other sites More sharing options...
pcakes55 Posted November 29, 2010 Share Posted November 29, 2010 You could probably save money and time if you just leave the camshaft and valves on the bench when you reassemble instead of using a cam like that. lol.. But really, stock cam is more than adequate for 300hp. If it all checks out good at the machine shop, stick with that. If you need to replace it, your wallet will probably be better off with buying another used stock cam for cheap than a performance cam; And then you'll have more money for other things. If your power goals were higher, it'd be a different story. If you really want to splurge though, there's plenty of cam choices. But the one you listed is not ideal Research. Quote Link to comment Share on other sites More sharing options...
Xnke Posted November 30, 2010 Share Posted November 30, 2010 I am not sure how these folks are getting along with that cam being so bad. No one here can tell you what that cam will do, based on the information you have given us. The lift and duration is not enough to figure anything out; you'd want to know the lift, duration, lobe centers, and lobe separation. With turbocharged engines, camshaft selection is a bit of black magic; in my opinion. supercharged, nitrous, naturally aspirated, all those engines are easier to choose a cam for; but I am not sure why. I know that for a naturally aspirated, you want some valve overlap, you want to choose a cam that is not too big for the induction, and one that is not too big for the exhaust. Long duration cams make more horsepower at higher CFM's, and high-lift cams tend to allow easier breathing, to a point. The key is matching the cam to the engine, and with a stock turbo intake manifold, a stock turbo head, and a stock turbo exhaust manifold, the factory turbo cam is fairly well suited for engines up to 250HP, and is adequate for engines up to 300HP, given that you have the fueling and engine management systems to support such. You say that you've read about the stock cam running out of steam at 5-6Krpm...did you know that the stock intake manifold runs out of flow at about that point, as well? I would call around to the cam regrinders, and talk to them. True, it's not needed for the power levels you are looking at, but you may get some tidbits of information that would help you better decide what you want. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted November 30, 2010 Share Posted November 30, 2010 (edited)  You can make more than 300hp (intercooled) with the stock cam, intake, and porting, just to clarify.  It just begins to get harder and harder (read inefficient) after that.  Not only because of the cam.  Free breathing exhaust, no fueling or timing limitations, decent intercooling, and boost, are the main ingredients needed in the 300-400hp range.  Stock cam and long block will do. Edited November 30, 2010 by cygnusx1 Quote Link to comment Share on other sites More sharing options...
Leon Posted November 30, 2010 Share Posted November 30, 2010 I am not sure how these folks are getting along with that cam being so bad. No one here can tell you what that cam will do, based on the information you have given us. The lift and duration is not enough to figure anything out; you'd want to know the lift, duration, lobe centers, and lobe separation. I can guarantee you that a cam with a duration long enough to open the intake valve through 64% of an engine cycle will make no horsepower. With turbocharged engines, camshaft selection is a bit of black magic; in my opinion. supercharged, nitrous, naturally aspirated, all those engines are easier to choose a cam for; but I am not sure why. I know that for a naturally aspirated, you want some valve overlap, you want to choose a cam that is not too big for the induction, and one that is not too big for the exhaust. Long duration cams make more horsepower at higher CFM's, and high-lift cams tend to allow easier breathing, to a point. No magic required. A turbocharged engine will make more power higher in the powerband with a longer duration cam, because of an improvement in high speed cylinder scavenging. This improvement comes at the expense of low end volumetric efficiency because of gas reversion and a higher percentage of unburned fuel. Higher lift equals higher flow, there is a point where increasing lift won't gain more power and that's when port area is overwhelmed by valve curtain area. And typically, the cam you choose doesn't depend on intake and exhaust sizes, it's the other way around. An experienced cam grinder will likely be able to head you into the right direction when choosing a cam as Xnke mentioned. Point is, the PO has much research to do, but the info is there (especially if you search the archives). A cam grinder will help, but some background goes a long way. Quote Link to comment Share on other sites More sharing options...
Pyro Posted November 30, 2010 Share Posted November 30, 2010 If you plan on using the stock turbine then you should not use a cam with any overlap. The stock turbine make lots of exhaust manifold back pressure and therefore doesn't tolerate overlap (intake and exhaust valve open at the same time). A good upgrade for a mild turbo build is to use a cam from a NA engine. The NA cam has 8 more degrees of duration and is good for another 500 rpms of usable power (5500 rpms) and doesn't have enough overlap to mess with the turbine. Quote Link to comment Share on other sites More sharing options...
bfsnail Posted November 30, 2010 Author Share Posted November 30, 2010 I fail at copying text apparantly... Lift(In/Ex): .460/.460 Duration(In/Ex): 270/260 (straight from the z store) But it turns out my original cam is going to be just fine. Thanks for the helpful replies, since posting in desperation last week I have talked to a few others and read a few things and basically came to the conclusion that was found here. With the power I'm looking to get, money would be better spent elsewhere if the original cam is still good. One step closer to a fun car... Quote Link to comment Share on other sites More sharing options...
bfsnail Posted November 30, 2010 Author Share Posted November 30, 2010 I fail at copying text apparantly... Lift(In/Ex): .460/.460 Duration(In/Ex): 270/260 (straight from the z store) But it turns out my original cam is going to be just fine. Thanks for the helpful replies, since posting in desperation last week I have talked to a few others and read a few things and basically came to the conclusion that was found here. With the power I'm looking to get, money would be better spent elsewhere if the original cam is still good. One step closer to a fun car... Quote Link to comment Share on other sites More sharing options...
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