panachedk Posted January 19, 2008 Share Posted January 19, 2008 Alright, I've been doing lots and lots of reading on this site, and some others trying to figure out which cam would work best for me. This will be for my l28et with a p90a (converted to solid lifter) track car. I do mostly road racing (Road America twice a year, but mostly shorter tracks and occasional auto-x). I have a little larger turbo than i need (plan on getting a better sized for my needs within the next month or so. I would like to see around 350-400 hp. I have seen it said that the stock cam is good to these numbers, however I am curious if there is a better choice for my set up. Thanks for any help guys. I am truly lost here. Adam Quote Link to comment Share on other sites More sharing options...
tomz Posted January 26, 2008 Share Posted January 26, 2008 Unless you want to spend a lot of money for new springs, and head work, your about @ max lift with the stock cam. Lift is just about the only improvement you could make except for minor opening and closing events of the valves. The good news is that for your HP objective, the stock cam will work fine. Just shoot for 13-15LBS of boost, pick the right turbo, don't take short cuts and your there. On the other hand you could dump that motor, and put a real one in there and forget the turbo. Your HP would be there, and you could run pump gas. Quote Link to comment Share on other sites More sharing options...
Pyro Posted February 4, 2008 Share Posted February 4, 2008 77 to 80 z/zx NA has 8 more degrees on the intake than a stock turbo cam. And it will slide right into a P90 head. Check out the stock cam specs. You need a 77 or new model to fit the P90 head (internally oiled). Good for another 500 rpms, and rpms make hp. Quote Link to comment Share on other sites More sharing options...
Pyro Posted February 4, 2008 Share Posted February 4, 2008 check out this site http://www.atlanticz.ca/zclub/techtips/cam/index.htm NA (77 to 80) cam 248/248 (intake/exhaust) turbo cam 240/248 or 240/240 Quote Link to comment Share on other sites More sharing options...
datman Posted February 7, 2008 Share Posted February 7, 2008 I have the NA cam in my turbo l28....runs very well, pick up is great and puls hard all the way to 7k. Quote Link to comment Share on other sites More sharing options...
tomz Posted February 8, 2008 Share Posted February 8, 2008 check out this site http://www.atlanticz.ca/zclub/techtips/cam/index.htm NA (77 to 80) cam 248/248 (intake/exhaust) turbo cam 240/248 or 240/240 The extra 8% is before TDC. This is bad for a turbo, because if it opens early, you get back pressure, and extra heat. Nissan made this a turbo cam for a reason, cause it works good with boost. NA cams use overlap to scavenge the cylinder. Can't scavenge with forced induction, especially turbo,s. I've seen this head, cam combo make 500HP with intercooler. just crank-up the boost. Quote Link to comment Share on other sites More sharing options...
83zed owner Posted February 8, 2008 Share Posted February 8, 2008 so using the stock cam is good to 350 - 400 hp on a zx ?? can i use the n/a cam on a p90 head?because am recently rebuilding my n/a motor to a turbo with forged pistons custom made intake manifold and turbo header. Quote Link to comment Share on other sites More sharing options...
Pyro Posted February 8, 2008 Share Posted February 8, 2008 The extra 8% is before TDC. This is bad for a turbo, because if it opens early, you get back pressure, and extra heat. Nissan made this a turbo cam for a reason, cause it works good with boost. NA cams use overlap to scavenge the cylinder. Can't scavenge with forced induction, especially turbo,s. I've seen this head, cam combo make 500HP with intercooler. just crank-up the boost. Don't think only 8 degrees more duration is going to spoil the power. 248 degrees is so small that the overlap at 0.050" lift is still a negative number (no overlap, around -18). At advertise duration (248, and 109 lsa), the overlap is 30. My msa turbo stage 1 cam (260/250, 114 lsa) has 27 degrees overlap at advertised duration. So, not a big deal to have 30. Sure, turbos don't like overlap, but a small cam (like a stock na cam) doesn't have much overlap. And I have run the na cams before with a turbo is they run well and give another 500+ rpms of useable power. The turbo cam lays down around 5000 rpms. Quote Link to comment Share on other sites More sharing options...
tomz Posted February 9, 2008 Share Posted February 9, 2008 Don't think only 8 degrees more duration is going to spoil the power. 248 degrees is so small that the overlap at 0.050" lift is still a negative number (no overlap, around -18). At advertise duration (248, and 109 lsa), the overlap is 30. My msa turbo stage 1 cam (260/250, 114 lsa) has 27 degrees overlap at advertised duration. So, not a big deal to have 30. Sure, turbos don't like overlap, but a small cam (like a stock na cam) doesn't have much overlap. And I have run the na cams before with a turbo is they run well and give another 500+ rpms of useable power. The turbo cam lays down around 5000 rpms. The thing is that your msa cam has a 114% lobe ctr which would make it ok. The stock turbo cam runs on a 110% lobe ctr which makes a BIG diff. Had you rather make 500HP at 5000 RPM or 500HP at 5500 RPM. Quote Link to comment Share on other sites More sharing options...
Pyro Posted February 10, 2008 Share Posted February 10, 2008 The thing is that your msa cam has a 114% lobe ctr which would make it ok. The stock turbo cam runs on a 110% lobe ctr which makes a BIG diff. Had you rather make 500HP at 5000 RPM or 500HP at 5500 RPM. 248 degrees of duration is still a tiny cam with hardly any overlap to speak of even with 109 or 110 lsa. I know my msa cam is using 114 lsa. So that makes the overlap about the same with the msa stage 1 turbo cam as the stock na cam. Yes, I did the math. Both cams (msa stage 1 and the na) do have more overlap than a stock turbo cam that is for sure. However, my msa cam sure makes more power than a stock turbo cam. Do you want to make 500 hp with 30 psi of boost or 25 psi of boost? Quote Link to comment Share on other sites More sharing options...
tomz Posted February 10, 2008 Share Posted February 10, 2008 What I'm trying to say is said best here. http://www.turbochargedpower.com/Camshafts.htm. Now I'll shut-up and go work on my 331 sbf 90mm turbo "72Z. Quote Link to comment Share on other sites More sharing options...
Pyro Posted February 11, 2008 Share Posted February 11, 2008 nice link! Thanks, I'm always looking for cam tech papers. I agree with you 100%. overlap is not a good thing for a turbo engine (especially with a smallish turbo). However, the stock NA cam is so small that is doesn't have enough overlap to worry about. The link focuses on when the exhaust valve closes and when the intake valve opens (overlap). If you look at the spec specs there is hardly any difference when the Z turbo and NA cam There are 3 turbo cams and have exhaust closure at 14, 8, and 6 atc, the non turbo 75 to 80 cam exhaust valve closes at 14 The turbo cam intake valve opens at 12 or 16 btc and the na opens at 16 btc. so the turbo cam with the most overlap is 26 degrees, the 77 to 80 na cam has 30. hardly any difference. However 8 more degrees on the intake does make another 500+ rpms of useable power. Quote Link to comment Share on other sites More sharing options...
jeffp Posted February 14, 2008 Share Posted February 14, 2008 A cam will work well provided the application of the cam is realistic. You need to know what your power curve is to be 4K 5K and up. The falicy of a cam with overlap creates problems with the turbo engine is not all together true. My cam for example has 54 degrees of overlap. To much for a turbo engine right? Wrong! my cam is putting my power curve from 4000-past 7K so to say across the board that overlap and duration is bad for a turbo engine is just not correct. Realistically, to get the power inthe higher rpm levels, you are going to need duration and lift. Match the cam to the capabilities of the engine. The stock cam will work for you, but the power will be way down by 5500 rpm's, so if that is what you are looking for then use the stock cam. There really are not a specific application for a particular cam, the head flow is going to determine if you are under cammed or over cammed. A overcammed engine will be doggy at low rpm's, and a under cammed engine will be bad on the top end. just something to think about. Quote Link to comment Share on other sites More sharing options...
Pyro Posted February 14, 2008 Share Posted February 14, 2008 Yes, good point jeff. I should steer away from those "general rules". It seems the amount of overlap tolerated by a turbo engine depends on the pressure in the exhaust manifold. Therefore, high flow turbines and free flowing exhaust manifolds can handle more over lap. When using a stock turbine on a L28et, avoiding overlap would be a good thing, since the exhaust pressures can become much larger than the intake pressure. Quote Link to comment Share on other sites More sharing options...
tomz Posted February 14, 2008 Share Posted February 14, 2008 Just curious guys. Are we talking about a "bad to the bone" street car, or a "track only" car? What application are we talking about. I mean a $3000 motor or a $30000 motor. A 3ltr motor, or a 6ltr? Quote Link to comment Share on other sites More sharing options...
Pyro Posted February 15, 2008 Share Posted February 15, 2008 Could easily be a mild street car. Just install high flow components on the exhaust side to lower the exhaust side pressure. As your article says, "if the exhaust pressure is lowered than the intake pressure there will be no reversion" or something to that effect. Install a setup like this on a stock engine and it could handle more overlap. (T3 stage 5 turbine, high flow down-pipe, external wastegate, and a ported exhaust manifold). However, high flow exhaust components tend to make turbo lag. Quote Link to comment Share on other sites More sharing options...
OneSickZ Posted March 13, 2008 Share Posted March 13, 2008 I'm getting ready to test a 280/270 480/460 lift cam on a 109lsa on a V6SOHC 3L VG with 8:5 CR and a target boost of 30-35psi on a big ball bearing hairdryer. (61degree overlap) what are your guess of its manners? I've been told by 50 experienced ppl to use high lsa and another 50 highly experienced ppl told me low LSA. soo.. Its all in the air till you test it. I also read somewhere that a poor flowing exhaust manifold will benefit from a low lsa (I need to find that link again.) My last cam had 50degrees of overlap and was awesome! but it was on a 112lsa which doesn't matter as it was still at a 50degree overlap. Also the Cam Ron Isky reccomed i used showed a 56degree overlap. Quote Link to comment Share on other sites More sharing options...
tomz Posted March 19, 2008 Share Posted March 19, 2008 I'll put it this way. I'm running a ford boss block @ 5.4 ltrs,with a built to the hilt bottom end. Thumper turbo. The cam is a comp cams turbo cam, 580/580 lift on a 114LCA 246/236 @ 050. 624TRQ @ 3500, 984 HP @ 6500. At 20LBS Sounds like you might get quite a bit of lag, unless your going to spin this this thing into the stratosphere. I would suggest if nothing else, go with a bigger LCA. Good Luck, Tommy Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted March 19, 2008 Administrators Share Posted March 19, 2008 624TRQ @ 3500, 984 HP @ 6500. At 20LBS Tom, Something doesn't quite add up in those numbers... To make 984HP @ 6500, you'd have to be making 795 lb/ft, but you only report a max of 624. Is there a typo in there? Quote Link to comment Share on other sites More sharing options...
tomz Posted March 20, 2008 Share Posted March 20, 2008 Nowhere does it say max on either figure. This is just my power band. My power comes on at 35 annd I shift at 65. Your assuming these are peak figures. Quote Link to comment Share on other sites More sharing options...
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