Hello everyone! I haven't posted in a while but I still browse from time to time and my interest in my TGP is increasing now that my Syclone is done for the winter.
I noticed on W-Body.com that TGPilot owns two LG5 powered vehicles that both peak their HP and torque around 3700 RPM and I found that incredibly interesting, because my own vehicle seems to show the same results. I didn't dyno it but my datalogger has a feature called "Datamaster Dyno" that uses controlled acceleration over time on a flat plane, to calculate horsepower and torque. Basically you drag race your car on a flat road and it records the data, and then it does the math to figure out the amount of work it would take to accelerate a vehicle "x" heavy with each frame of recorded data. I have found the other calculators in Datamaster to be very useful, for instance the "Quarter Mile Calculator" is usually very close (within 1-2 tenths and MPH) when compared to actual dragstrip timeslips.
Anyways, I can't say if the Dyno calculator is accurate too, but the important part is the power curve and the RPM it occurs at, because that part I believe to be accurate since it is sensing when the vehicle is accelerating (increasing rate of speed) the hardest. Here is what a typical one of my Datamaster Dynos looks like (with zero drivetrain loss correction, or WHP/WTQ in other words). I had to ease into the throttle to avoid wheelspin, so the HP/TQ comes on a little later than it possibly could:
(http://s95370645.onlinehome.us/tgp/images/19102dyno.png)
Is this typical for all TGPs? Is it just me and Kenny's two cars? Mine has 170K original miles (motor runs solid) and I'm wondering if the valve springs are tired. I noticed the same thing in a post I made about 1.5 years ago: http://www.tgpforums.com/tgp/viewtopic.php?t=1881&highlight=
If it's not the valve springs, is it just that the tiny T25 exhaust housing is so restrictive, it actually chokes horsepower in a negative direction after 3700? Whatever the case, on my car I can certainly feel the huge pull (torque) somewhere between 3000-4000 and after that it's quite a bit weaker.
What chip are you running? 8)
i reached peak HP around 4400 RPM and peak TQ around 3200 RPM. the setup in my Cutlass is nearly identical to Kenny's red TGP IIRC, and my dyno #s were very close to his as well:
http://www.turbosedan.com/cutlass/dyno3.jpg
mods: TGP setup, 5-speed conversion, grainger valve MBC @ ~10psi, K&N cone directly on compressor inlet, TGP/5-speed chip by god910, test pipe + cheapo straight thru bullett style muffler (single outlet). 234,000 miles and counting on a never-been-rebuilt shortblock :)
Whoops - sorry I forgot to mention those. I've got a TopGun 160 chip that I lightly modified, a Jeff M crossover pipe, K&N on filter, and a Boostvalve.com ball and spring-style manual boost controller set at about 11 PSI.
TurboSedan - that's interesting and I've seen your dyno sheet before. Yours is what I'd expect mine (and Kennys') to look like. My car led a hard life with me winding it to 5200 RPM frequently in the recent half of its life. What about the possibility your valve springs have less wear than mine (easier life)? I don't really know how to replace them otherwise I'd have already done it just to find out if it improves the top end power, but I'll pay to get it done (or learn myself) if I can figure out if it's necessary..
When I dynoed mine stock it made peak torque low in the powerband (a little below 3k IIRC) and peak power was around 4600 or so. Now with the chip, cam, topend, ported exhaust manifolds, etc...., I would expect it to peak at around 5k or so, and torque in the 3500 range.
Shawn
Alright, why is it that when I try to use that HP calculator, I get garbage, it makes NO sense whatsoever. I think it's cause I have a manual maybe???
There's a real technique to using the Datamaster Dyno.. You've got to get a good gear sample to begin with, and then set the Start and End records properly, and the RPM should only increase between those two (you don't want any negative RPM dips). Then take a look at the rest of my screenshot for the settings. In a 4T60 tranny 1.57 is 2nd gear ratio, the car came with 3.33 gears, I weighed it on an industrial truck scale for the weight. The rest of the settings I came up with by deduction from various sources and I feel they are close enough. Finally, set the Output Filter Factor to 8 or it can skew the curve peaks from reality. Oh and the Drivetrain loss is up to you.. 0% = WHP/WTQ. I use 20% drivetrain loss when trying to figure Crank power.