This wasnt the final result but the only one i had on my hard drive (added another degree of timing after this). Does this curve look right to you guys? See attachment. Feels like its dropping off on the top end even after the blower cams...... Time for the eaton to go!
Dyno Graph
- Thread starter Modular2v
- Start date
-
Sponsors (?)
sneaky98gt
10 Year Member
It seems like the power may be falling off just a bit, but I don't think the Eaton is all of the problem. Looks like your peak power is just barely above 6000 rpm. On my last dyno, with an unported blower, stock heads, stock exhaust manifolds, and the blower cams I'm running, I think peak power was at about 6200 (I'll have to dig up the dyno sheet to be sure). That's on a blower manifold MUCH less efficient than the setup you have. And I'm not spinning the blower a whole lot either (3.3 pulley on stock GT crank pulley). That would lead me to conclude that the blower isn't all of your problem, and that the heads are likely just as much a restriction. A bigger, better blower would surely net more power across the band, but I suspect the curve will still look close to the same.
How fast are you spinning the blower? What upper and lower pulley combo?
Also, how much timing are you running? What's the timing curve look like? It's also possible that your tune has the max timing at XX degrees with a really aggressive ramp in, which means that it may reach max timing at an earlier RPM than redline, say like 4500 rpm. Without methanol, that's exactly how my car's tune is, and it falls on its face after 5000ish rpm, but still makes good torque down low. But with the methanol, it continues the ramp up with the RPM all the way to 6000 rpm (unless the IATs are too high, at which the tune backs off the max timing and the curve will plateau out at that point). If your timing curve is plateau-ing, or even decreasing if the blower is making a lot of heat, that could cause the power to back off up top.
How fast are you spinning the blower? What upper and lower pulley combo?
Also, how much timing are you running? What's the timing curve look like? It's also possible that your tune has the max timing at XX degrees with a really aggressive ramp in, which means that it may reach max timing at an earlier RPM than redline, say like 4500 rpm. Without methanol, that's exactly how my car's tune is, and it falls on its face after 5000ish rpm, but still makes good torque down low. But with the methanol, it continues the ramp up with the RPM all the way to 6000 rpm (unless the IATs are too high, at which the tune backs off the max timing and the curve will plateau out at that point). If your timing curve is plateau-ing, or even decreasing if the blower is making a lot of heat, that could cause the power to back off up top.
I really believe the heat soak has a lot to do with it..... this tune was done without meth. There is 16 degrees of timing in the car right now. The runs AMAZING when i pull it out of the garage in the morning and pulls until 6500rpm and wants more but 10 miles down the road it feels like it loses 50hp above 5000rpm. Im not sure what the timing curve looks like but i could find out. Many said the IAT's were up there! The blower has a 2.76 upper pulley and whatever the standard lower torktech is. Its making 10-11lbs of boost
sneaky98gt
10 Year Member
Yea, if the IATs are going up a lot towards the end of a run, then a good tune would pull timing according to keep it from knocking. Consequently, the peak power would be lower in the RPM band.
16 degrees isn't a ton of timing (I run about 13 across the board with no methanol), and I suspect that it gets to that 16 pretty quick, and then levels off. All other variables the same, this would create good torque down low with the torque falling off more quickly up top than if the timing ramp kept going up.
For reference, on my non-intercooled meth setup, with the meth spraying, my street tune runs about a max of 20 degrees at redline, and the track tune about 24 degrees at redline (6200ish RPM). If the IATs are REALLY cool (cold ambient air, cool motor, and lots of methanol), then it may reach that max number before redline (sometimes as low as 5000 rpm) and plateau from there. This is good, because it means I make more torque in the low and mid-range, but still keep it safe up top at redline.
Your's probably has a max number higher than 16, a ramped function that the tune would default to if everything was perfect (cool IATs, cool engine temp, etc.), but since the IATs are going up, it pulls it back to 16 to keep it safe, and thus the torque laying over up top a bit. This would also explain how much more power it has when there is no heat soak at all.
16 degrees isn't a ton of timing (I run about 13 across the board with no methanol), and I suspect that it gets to that 16 pretty quick, and then levels off. All other variables the same, this would create good torque down low with the torque falling off more quickly up top than if the timing ramp kept going up.
For reference, on my non-intercooled meth setup, with the meth spraying, my street tune runs about a max of 20 degrees at redline, and the track tune about 24 degrees at redline (6200ish RPM). If the IATs are REALLY cool (cold ambient air, cool motor, and lots of methanol), then it may reach that max number before redline (sometimes as low as 5000 rpm) and plateau from there. This is good, because it means I make more torque in the low and mid-range, but still keep it safe up top at redline.
Your's probably has a max number higher than 16, a ramped function that the tune would default to if everything was perfect (cool IATs, cool engine temp, etc.), but since the IATs are going up, it pulls it back to 16 to keep it safe, and thus the torque laying over up top a bit. This would also explain how much more power it has when there is no heat soak at all.
i also didnt have the cams in the graph directly above this post
exactly what im thinking. did you see how the old graphs kinda followed the same trend?
Similar threads
