240Z Turbo Posted May 30, 2001 Share Posted May 30, 2001 After painful research in the area of cam selection for a turbo L motor I have finalized my decision. Man, talk about both ends of the spectrum on what is recommended to be run. I have to admit I am no expert in this area and without personally seeing what works I can only go by what other say. Anyway, here it is: .488" lift @ valve 230 duration @ .050" valve lift 110.5 lobe centers This is basically the 155 grind from Web Cams, but I had then push the lobe center further apart. Ultimately I would probably like a cam with lift in the .510" range for my particular setup, but this is a good starting point. It is a slight step up from TimZ's cam, Isky Stage I, that has the following specs: .474" lift @ valve 222 duration @ .050" valve lift 109 degree lobe centers If this cam works well I will probably have Crower make me an identical cam, but with the .510" lift. Quote Link to comment Share on other sites More sharing options...
pparaska Posted May 30, 2001 Share Posted May 30, 2001 For a motor of that size, isn't 230 @0.050" valve lift pretty big? Hell, that's on the edge of what many think is streetable on a 5.7 liter motor. (Of course, street may be of no concern here.) This is assuming that the "smaller engine, less duration" rule of thumb holds. 8 degrees is not a small amount (230 vs. 222) on a 5.7L motor, and it's even more significant on one half as big, I'd think. If it were a normally aspirated motor, I'd think this cam would be peaky, up above 4000+ rpm being the bottom of the powerband. Will the Turbos negate the large duration effect? Sorry, I'm pretty clueless about camming a turbo motor, but I thought that less duration (on the intake at least) is needed for a turbo motor, and overlap should be avoided at all costs. Would more lobe separation be better, if you were concerned with low and mid range? Note, the above are more questions than answers. That cam ought to be a monster on the top end with two big turbos! Quote Link to comment Share on other sites More sharing options...
240Z Turbo Posted May 31, 2001 Author Share Posted May 31, 2001 You know what? I don't have a clue how this thing will react, but I think I will be happy. I am as much in the dark as most are, but have gained some knowledge in this area. The 8 degrees duration should be a 500rpm improvement for peak power over TimZs cam. The lobe centers are the overlap and by going from 109-110.5 lobe centers I have decreased the valve overlap 2 degrees on this cam. Only time will tell. Quote Link to comment Share on other sites More sharing options...
pparaska Posted May 31, 2001 Share Posted May 31, 2001 I agree the lobe center opening up by 1.5 degrees helps, but it doesn't offset the added duration (8 degrees wider on the intake and exhaust both) and your overlap goes up by 5 degrees (according to Desktop Dyno's Cam tool). That'll raise the power band a bit. I can't imagine what that thing is going to feel like when the cam comes on and the turbos hit! I hope you have one hell of a drivetrain and tires behind it? (Or maybe let the tires be the safety valve!) You probably already need to have your head against the seatback in preparation for the boost hitting! I'd love a ride in that thing! Quote Link to comment Share on other sites More sharing options...
randy 77zt Posted June 1, 2001 Share Posted June 1, 2001 way back in early 80s bmw had a 1500cc f1 motor that made a little over 1000 hp-proof if you feed enough fuel and air the hp keeps climbing.the problem with something built like this is that it doesnt make power untill 4000 or 5000 rpm and then it switches on like the powerband on a 125cc dirt bike.by then that high torque v8 got 3 car lengths on you.but it is nice to hear of some body that has the courage and creativity + money to experiment.good luck with the turbo motor-maybe all the turbo guys should kick in a contribution and share in the newly gained info. Quote Link to comment Share on other sites More sharing options...
clint78z Posted June 1, 2001 Share Posted June 1, 2001 Alot of people scratch their heads when it come to small engines making big HP. What exactly do they do to make a 1.5 put out 800HP. The first big secret is they switch to alcohol, you can run way more igition advance, boost and is much more stable. The entire motor is balanced and the usuable rpm is shifted way up. This cuts down on engine life considerably. I heard that BMW's engine pegged there 1500hp dyno, it was dialed back for reliabilty. On the last lap they would up the boost and run full out. Quote Link to comment Share on other sites More sharing options...
pparaska Posted June 1, 2001 Share Posted June 1, 2001 quote: Originally posted by clint78z: Alot of people scratch their heads when it come to small engines making big HP. What exactly do they do to make a 1.5 put out 800HP. That'd be me . quote: The entire motor is balanced and the usuable rpm is shifted way up. This cuts down on engine life considerably. Sounds like a fine drag race engine, a horrible autocross engine, and a good road race engine (if you can keep it in the power band). Sounds like a TERRIBLE street engine. I guess that's why I like the idea of high 3 liter and bigger engines for turbo use on the street, with low spool rpm. I gotta get a ride in Scottie's car! Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted June 2, 2001 Share Posted June 2, 2001 Hey Mike, got rained out last night so will try again next Wed if the weather holds up. Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted June 3, 2001 Share Posted June 3, 2001 I had the good fortune to go for a ride in Scottie's car on Memorial Day!! It was exhilirating to say the least for me, but just a walk in the park for Scottie. That pickup we went around on the straight away must have heard the SONIC BOOM left behind after the acceleration!! Better than Disney World! Quote Link to comment Share on other sites More sharing options...
Z-Gad Posted June 4, 2001 Share Posted June 4, 2001 Hey scottie, I figured you got rained out...I'll make every effort to go Wednesday as well. Mike Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.