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My 87 GT is powered by a 347 which was still Speed Density (till Nov/02) and ran
very strong. I was going to drop down to a 331 once this motor tired but I
ended up staying with this size motor and decided to just upgrade the lower end
a bit more and run a cam better suited for a 347 now that I'm mass air. Many
people think that Speed Density can't handle modifications such as heads, cam,
larger injectors, Intake, Blowers & Nitrous. This is simply NOT true. It's all
in the timing event's of the cam, fine tuning of fuel pressure, TPS & base
timing. I ran Eddy Alum Heads, a Custom cam, 24lb injectors, Cobra Intake &
Shorty Headers all on SD. (I now run a Edelbrock RPM & 30lb Inj's). With this latest cam I'm having
ground and the much lighter rotating assembly being put together, the cobra
intake just won't be enough and will hurt top end HP & TQ to much. As you can
see though virtually all of the same things that a MAF (Mass Air Flow) car use's
can be used with SD with NO ill effects at all. SD DOES have a limit though on how far
you can go in cam sizes.
The key issue's here are the Duration @.050. and LSA's. The cam should have no more than 216* (Intake) & 220*(Exhaust) MAX @.050. A LSA (Lobe Separation Angle) of 114-116 work's the best for a daily driven SD system and provides good vacuum and a clean burn. This is where a custom cam with the right timing events come into play). SD needs good manifold vacuum to run properly & strong. I was running a custom cam that spec'd at .520/535 Lift & 218*/224* Duration @.050 on a 114 LSA with 1.72 Roller Rockers and installed 4* advanced. I went with this size cam for max street performance (for an SD setup). My new cam will be designed around a MAF system with much more lift and much more aggressive ramp rates. I installed a ZEX Nitrous System using it's 125HP jet's. Now I'm stepping up to 150's since I have the fuel system upgraded to support to higher HP jets. For those who don't know, the ZEX system can support up to 200HP by using the "Iceman Solenoid" and jets can be used by any other N20 company such as NX, NW etc, just DO NOT use N.O.S brand jets as they will NOT work. You can also change the solenoid inside to which ever brand you prefer, so in essence, just about everything can be changed but the ZEX chip. I've seen them converted & painted and you would never know it was a ZEX system. I mounted the bottle this way on purpose so when I'm by myself or with my wife, I just lower the seat flat which makes it very easy to reach the bottle valve and the bottle sits at the proper angle. Then when I need extra room, I just raise it back up and it sits straight up and out of the way. I also Installed a nice ashtray switch panel (from AFM) for my N20 switches for a much cleaner look, easy access and they hide nicely when the lid is flipped over. This combo should satisfy my power needs. I always recommend a custom chip for SD when reaching the 350FWHP mark plus using 24lb injectors. Some people have used larger cams with SD (myself included), but low speed performance suffers and idle problems occur unless you use something like the TwEEcer. My old cam worked out very well, and idled very nice, healthy and stable at 975rpm with a mild lope to it, although it was a "hair" rich at an idle due to the 224* duration on the exhaust side. With regards to SD & blowers, Keene-Bell makes a nice setup for SD. All it takes is just a slight mod of the fish tank looking piece since it cannot bleed off the boost fast enough. Their are also other popular companies that make blowers for SD, but they just aren't advertised. You can always go DFI (Digital Fuel Injection) which happens to be SD or go with the TwEEcer R/T, then you can use much stouter cams, but for most daily driven street cars, DFI is usually overkill and a good DFI is very costly, but the TwEEcer R/T falls right into the perfect street/strip category and the cost is a little bit more than a new custom chip (approx $580). It uses the same cal edit software as a Speed Pro DFI system ( F.A.S.T) as it's called now, which stands for Fuel Air Spark Technology. Here's a little interesting fact. did you know that while Ford went from SD to MAF, that GM went from MAF to SD?. UPDATE 9/14/02 Due to California's VERY strict smog laws, I was forced to switch over to MAF to cure my hair rich problem at an idle. To pass smog here, my A/F ratio at an idle was 13.2 with SD and I needed 15.5 in order to pass. My cam had just a tad to much duration on the exhaust side to pass here in Calif. So far the benefit I've seen is my A/F at an idle is now tuned to 15.0 as it was 16.5 with no tuning. My top end power is a little better now with it leaner. Below is a pic of the completed conversion. I have the entire CAI tube wrapped with heat wrapping to keep the air as cool as possible and it has worked terrific, as before without the wrap the chrome tubing was so hot I could only touch it for a few seconds before burning my finger. Now that it's wrapped, I can put my hands on it and it's just mildly warm., so it is a big improvement towards keeping the air inside much cooler and the cost was just $15 for the special wrapping. UPDATE 12/10/02 I had an Autologic chip burned for it for best average HP, plus it's set up with 4 programs, 2 settings for diff N20 jet's, 1 for Peak N/A tune & 1 for smog. The factory rev limiter was raised to 6500 rpm, the EGR & Thermactor are turned off except for the smog setting, plus timing is retarded & fuel curve altered accordingly depending on which N20 jet I use. I was definitely impressed with the results the new chip made. Although my cam was made for an SD system, it worked just fine in a MAF system. UPDATE 5/12/03 I'm doing some big changes to the lower end and having a much better cam ground for it now that I'm MAF. My prior cam was designed around a speed density system. Now I can run a much better cam grind better suited for a 347 for more HP & TQ from 2300-6300 rpm with a broader & flatter TQ band and still pass Calif smog. Some of the changes will include 4340 forged ultra light rods & ultra light pistons, much stiffer valve springs to accommodate the more aggressive ramp rates of the new cam. This new rotating assembly will deffinatly spin up much quicker. I'm making these changes due to a noise in the lower end I didn't like at all and figured now would be a good time to put a much better cam in among other things. I won't be listing exact cam specs, but I will say that Ed Curtis from FTI will be grinding the cam. UPDATE 10/10/03 Fired up the new motor combo. Sounds very nice with a healthy idle at 900 rpm.. The motor ramps up much faster than before. Just need to do a little fine tuning, move a couple wires around, put some miles on it then hit the dyno (when time & money permits) to re-program my chip. I ended up spending TWICE as much than I had planned but isn't that the way it always goes? UPDATE 10/30/03 I did a little wire moving, fine tuned it as much as possible and the motor is running very nice. Idles rock steady at 900 rpm with no surging, no low end bucking down at 1800 rpm, fires right up when cold & runs nice & cool between 180*-185* with 12* initial timing. The MSD Distributor is in as are the Poly Trans & Motor mounts. I still need to get my UPR 3 way adjustable timing pointer in yet. Low end TQ is very impressive as is top end power. With approx 250 miles on it now, the motor revs past 6k very easy, but I'm keeping the RPM limit to 6000 till it's dyno tuned N/A & for the N20, till then, the N20 remains OFF. I'm sure glad the tires break loose very easy as that's the only thing keeping my tranny alive. The first picture below was my old combo, the second picture is my latest combo. You can see a much better & up close pic of the latest combo on the *Pictures Page*. UPDATE 1/10/04 I finally got 500 miles on the motor. I replaced my old tach with a new Ford Racing 5" monster tach with built in shift light. The old tach just didn't have enough lighting at night to read it clearly. I also am installing the dual 12" ram chargers electric fan setup so I can toss the flex fan. I'm also installing an adjustable timing pointer as my SFI Spec Power Bond balancer was little off on the timing marks. I've been running the motor several degrees retarded and didn't realize it right away, Now with it corrected, the HP & TQ picked up nicely. UPDATE 3/10/04 I now have approx 950 miles on the motor & it's running great and time to hook up the N20. Timing is now at 14* initial giving me 34* total by 2400 RPM. It's now running cooler at 175*-180* (in 80* ambient temps), I contribute the 10* cooler running temps to the motor loosening up a little. There's no unusual oil burning at all as many STILL believe the 347 is an oil burner. It's all about using the right parts and having it assembled correctly. I installed my UPR adjustable timing pointer, yanked out the A/C compressor & other parts as they were shot. The dual 12" electric fans & AC Delete kit should be done by this weekend as I want the cooling system maximized before the summer arrives, plus the few extra HP will be nice & the estimated 2-3 extra MPG (versus the flex fan) will help on the drive to AZ. NOTE, I just bought a new custom home in Surprise, AZ (Bout time I get out of this State). I will be out of this house before the end of April. Since the home won't be completed till Sept. From the people I've spoken too, it appears that *AZ Dyno Chip* is the place to go for Mustang dyno tuning, so once settled in that's where I'll get my chip re-tuned. With AZ's smog laws being a *tad* looser, hopefully I can alter the cam timing & a few other things for a little more power. UPDATE 9/19/04 Finally moved into the new home. so I thought I'd toss up a few pics of the car I had taken with my digital camera while watching the home being constructed. I have more to take as a couple pics show the construction going on around us. UPDATE 6/5/05 I finally got the car down to Keith at AZ Dyno chip for a new SCT custom chip. My A/F was very lean at 15 to 1 (which explains the very high MPG on the trip from Calif) After many dyno pulls Keith got the A/F nice & safe at 12.5-13.0 across the power band. I now average 18 city & 23 freeway MPG which is still real good. HP peaks at 5800 RPM while TQ peaks at just 3700 RPM with total timing set at just 28* (which is great for a stroker motor). The motor has a very broad & flat TQ which is just what I wanted. I wasn't looking for a high RPM motor as it's just my weekend driver that see's only 1000-1200 miles a year plus I still make plenty of HP & TQ to split this block so I keep my RPM's to 6200 max (even though it's still pulling real hard) Motor fires up instantly when cold, rev's up soo much smoother & faster now with the new SCT chip & tune & Idle's perfectly at 1000 RPM. The motor runs at 180-185* no matter how hot out, even in 115* plus heat. Those Ramcharger fans do a wonderful job out here, but with A/C being added, I didn't want to take the risk that they *Might* fall a tad short and not provide enough cooling for my special needs. UPDATE 7/16/05 I am upgrading my radiator & fan setup to the Mark VIII with the DCC unit built into the fan and a Ron Davis Alum radiator since I'm going to add a new upgraded A/C system back in the car with an upgraded condenser (33% more efficient than stock) & I wanted to make sure I have the best cooling & fan setup made so I won't have any worries about cooling when sitting in idle traffic when it's 115* plus outside with the A/C on full. I thought I could work around the heat here but it's just too hot for my illness to withstand while driving (110* inside the car). I also added new Diamond E2 Projector headlights with clear corners & silver star bulbs to improve lighting at night considerably, and what a nice difference they made compared to stock plus they look cleaner IMO and changed the entire front end look for the better. UPDATE 7/27/05 Installed CGC's new cowl gauge panel with molded in gauge cups. The gauges installed inside it are Auto Meter Ultra Lite series 2 5/8" Oil Pressure & Fuel Pressure. I'm very impressed with how well this gauge panel installed & cleans up the lines of the car plus giving me 2 more places to add gauges in a way that doesn't look gawky or interfere with the drivers line of sight, thus giving me much better visibility. Stop by CGC's web site at CGC Concepts I also changed out my Dynomax ST Mufflers for a pair of Magnaflows which have a much higher CFM flow rating, 1138 CFM for the Mag's versus 410 CFM for the Dynomax ST's. Mag's flow equally as well as Dynomax Ultraflo's but their much cheaper ($50 a piece). The car has a noticeable deeper tone at idle and a little bit louder & much louder at WOT. I went with them due to being a straight thru design rather than chambered. Now I have a complete Magnaflow exhaust system except for the LT's. **SPECIAL THANKS** to Ed Curtis of FTI. He assured me that the camshaft he made for me would pass *Calif* smog. I was still a tiny bit skeptical considering the 8* overlap I had, The ONLY change I had to do was add on my tail pipes so AZ's smog probe would work correctly. I left the FP up, Timing up and did no fancy tricks of any kind and the motor passed right thru on the first try with a tiny bit of room to spare. I was allowed 1.6 HC's at an idle and the motor delivered 1.1 The other 3 figures were so clean it's not worth talking about here, but it does explain why I averaged 27 MPG from Sac, Calif to Surprise, AZ (850 Mile Trip). Who say's a N/A 350+RWHP/385RWTQ 347 can't get good mileage on the freeway even with 3.73's?
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