speed density October 20, 2004, 03:56:57 AM Hello, I am new here but I have an oxford white xr-7 that I am building a 306 HO to run with an 1988 mustang manual speed density computer. How many of you have done an HO conversion with speed density? What kind of mods did you use such as cam, heads, intake etc.? I found a cam from Crane which they say was designed for speed density HO 5.0L, and I am having a set of e7's built with gt40 valves installed and will be using stock HO upper and lower intakes with 65 mm throttle body and egr plate. I have already purchased most of the parts and the 306 is on a stand ready to be built. I have decided to go speed density instead of mass air so I need to make sure this will run right before I assemble the car.From what I have learned these speed density computers require a certain amount of vacuum to run, is making the engine breathe a little better(except the stock intake which will probably be a bottleneck) going to make a difference? Quote Selected
Re: speed density Reply #1 – October 20, 2004, 10:43:04 AM Speed density severely limits you on mods you can do affecting airflow. Other guys will have better info on this. Since you say the cam is designed for it, it should be ok, but the heads I'm not sure about.Can I ask why speed density? Quote Selected
Re: speed density Reply #2 – October 20, 2004, 03:39:20 PM The only problem you're really gonna have with a speed density setup is finding a cam that doesn't upset that style computer. The trick is to keep the vacuum up because speed density thrives on it. Look around at http://WWW.50tech.com its an informational mecca for speed density. I've used that site alot as my setup is speed density as well and I eventually plan on throwing a Kenne bell on it while keepin speed density. Quote Selected
Re: speed density Reply #3 – October 20, 2004, 10:56:47 PM I ran speed density for a while with a stock HO bottom end, ported E7s, full exhaust,explorer intake, blah. The key with Speed density is that you must create enough vacuum to run the Map sensor, otherwise there will be a rich condition, especially at idle. Having said that, you must run a cam with a wide lsa to keep vacuum up and lift below .500. Stock cam is 115* lope separation. Im running a comp cams N20 grind with an lsa of 114, .512/.512 lift. Even with that cam, the car ran extremely rich at idle. I had to convert to maf when I installed 24lb injectors, they would not work speed density for me. What are the specs on the cam you plan on running? Quote Selected
Re: speed density Reply #4 – October 20, 2004, 10:56:47 PM Thanks for the info, I found 1 person so far on the 50tech forums who has used the crane cam I plan on using. The rest of them have used a crower such as the 15511. Quote Selected
Re: speed density Reply #5 – October 20, 2004, 11:04:55 PM The cam is the Crane 444211. It is a dual pattern with 530/530 lift, 262/270 int 208/216 exh and 112 degrees lobe seperation. I called Crane before I ordered it and they told me this cam and valvesprings were designed for speed density. I don't see many people using it though, I hope it will not give me driveability problems. If I have to get it tuned, Anderson Ford in Clinton IL would be where I would take it. Quote Selected
Re: speed density Reply #6 – October 21, 2004, 01:14:38 AM If anything you might have to have a custom chip burned for your setup. You would benefit from one anyway provided you keep the same setup for a while. Just stick with 19lb injectors. If its any encouragement, I ran 13.8s on SD before I had to switch due to driveability problems. LaterRonnie Quote Selected
Re: speed density Reply #7 – October 21, 2004, 01:47:08 AM hey chrome302jr, what kind of driveability problems did you have? Did they just develop over time? What cam did you use in yours? The reasons I am set on speed density is I know mass air stuff is not cheap, don't want to re-pin the computer for mass air, already have the cam and I have a speed density cold air kit just waiting to be installed. I may later on decide to switch, but I just want to get it running and see how it does.Thanks for the input, these forums are great! Quote Selected
Re: speed density Reply #8 – October 21, 2004, 04:01:17 PM Quote from: whitebeastxr7hey chrome302jr, what kind of driveability problems did you have? Did they just develop over time? What cam did you use in yours? The reasons I am set on speed density is I know mass air stuff is not cheap, don't want to re-pin the computer for mass air, already have the cam and I have a speed density cold air kit just waiting to be installed. I may later on decide to switch, but I just want to get it running and see how it does.Thanks for the input, these forums are great!I ran speed density for a while, basically, until I put on the 24lb injectors. Here was my experience: I put on the windsor jr heads, explorer intake, and comp NX264hr n20 cam(very speed density friendly). At that time I was afraid of going lean with my 19lb injectors because I was running n2o. If I had stayed NA I probably could have kept the 19lb injectors and stayed speed density. The car ran like a raped ape at WOt throttle but was slightly rich at idle, causing it to surge and hunt. You might not have these issues, some dont as seen on 50tech forums. Converting to mass air helped my gas mileage and overall driveability. I didnt really see a difference at WOT. Hope this helps. If you do decide to convert to mass air, the stangnet article helps. Later Ronnie Quote Selected
Topic: speed density (Read 3184 times)
previous topic - next topic
