That's great documentation Bob! Things like this are as good as gold! ...
thinking about mildly porting my 4.7L heads now ....
-- Canuck -------------------------------------------- Y2K, 4.7L, 2wd, 5spd, The Ultimate K&N HomeBrew, Flowmaster CatBack, Home Ported TB, Electric fan conversion, 180 therm., Redline synth., IAT adjuster, HO Cams, HO Intake http://www.twistedbits.net/WWWProfile/dakota/Vyikam1jjgNN6"Bob Tom" <tigers@bserv.com> wrote in message news:5.0.2.1.0.20021126231810.009f0e40@bserv.com... > > For all you 1/4-milers, > > Last winter I ported my heads with the MP porting templates. > My decision for going this route came down to money. > > My SAE corrected numbers with the stock heads: > Peak HP: 226.1 @ 5000 > Peak Torque: 257.2 @ 4500 > > My SAE corrected numbers with the ported heads: > Peak HP: 241.7 @ 5750 > Peak Torque: 254.1 @ 4250 > > Unfortunately, circumstances dictated that two dyno shops > using different software and hardware were used so that > comparing the numbers is not exactly like comparing > apples to apples. Also, the printout that I got for the > ported heads were for increments of 250 rpm and not > the normal increments of 100 rpm for the stock heads. > Nevertheless, it gives a close enough ballpark figure of what > to expect. > > With my drivetrain loss, there was a gain of about 20 hp at > the flywheel. I certainly was pleasantly surprised to see that > the peak torque rpm had actually dropped a couple of hundreds > of rpms. I also had expected the peak hp rpm to rise but not quite > so high. > > As for track performance, weather and track conditions did not > come close to those where I ran my bests last year. 14.313 @ 95.05. > My best this year was 14.42 and I did up my trap speed to 95.92. > At the end of Sept. this year, I began to experience intermittent bucking > and misfiring in the high rpm range. Initial data indicated that the > problem might be air-fuel related and I concentrated on this area. > > Last week, I discovered the problem was the cap and rotor. All the > contacts were coated with a hard, thick, 'calcium-like' deposit. > I have never seen a condition like this. Looked like it went through > Jon's mud pit :-) > > Also, when the air temps. began hitting the 40Fs and below, I noticed > that my coolant temp. was around 150F (city/highway) and barely cracking > 160 at the track. The 180F tstat turned out to be partially stuck open > and I was running quite rich. > > Just to show you how much the above problems affect performance, the > dyno numbers with them are: > Peak HP: 217.9 @ 5600 > Peak Torque: 245.3 @ 4300 > > Next week I'll be replacing the RT cam with one that is closer match > to my MPI 4bbl intake and ported heads. > > Have a great Thanksgiving, all you USAers. > > Bob, Burlington, Ontario. >
This archive was generated by hypermail 2b29 : Fri Feb 06 2004 - 11:47:29 EST