RowJ

Time it from cruise...50 or 60 mph to max temp at WOT. Let others compare how many seconds it takes and compare. This should tell you if average or worse!

RJ

HOHN

Yes, until July

You want to see smoke, you should come to Cheyenne when it's pushing 100°! Density altitude gets over 10K feet easily. Those conditions would make even a STOCK truck a piston-melting, smoke-belching pig.

Let me tell you, I had some CRAZY SOP power when I was back in Cheyenne in the colder weather with the M4s. Even the high altitude wasn't enough to offset the benefit of 20° air


Another observation is that the turbo just "feels" way too small. Hard to describe, but it seems that large increases in boost do NOT produce large increases in acceleration. The pedal is linked to the boost gauge more than the speedo, if that makes sense.

I can barely tell any perceptible change in SOP acceleration from 15-20psi.

I'm tempted to go the the opposite extreme via large single, but I hate big smoke on the bottom.


Maybe we'll both just end up with some nice smallish twins. That's about 4 yrs down the road for me

BigBlue

IIRC, John Rodriguez replaced his probe with a very high end autometer (I think it was like $200) race probe and noticed a big difference in how fast it reacted. It went up a lot faster and a lot higher. His old probe was so slow to react it would never show him how hot it was really getting.

HOHN

The problem with this new Autometer NV pyro is that the probe is part of an integrated harness that plugs into the back of the guage. It's NOT like the Ultra-lite I had before where you can swap probes without touching anything else. (the two little screws on the yellow wire pair).

I wonder if this probe is cheaper than the one I had before??

My old AM probe used the braided stainless leads, and is what most of us are familiar with.

The new NV series pyro I have now came with a different probe: it's "L" shaped and uses a slip fit in the bung with a set screw on the side.


I wonder if my older probe was quicker to react?

Looking at Autometer's site, there's no pic of the "street" series probe to compare it to the "competition" probes for the NV series.

With my luck, the NV series FORCES you to have the street probe and no other.

jh

signature600

My old Autometer Pyro moves a lot faster than my Stewart Warner does now!!

Also, my SW shows ~100-200* cooler EGT that what the X-monitor does...I still can't decide whether it's cooler from being in the wastegated side of the turbo, or from something else?

Sounds like you need more air, HOHN!
Chris

HOHN

NO doubt--

which AM probe did you have on your old pyro?

signature600

"NO doubt--" what, because of the twins? The pyro moves faster and farther than it ever did with a single On the Dyno, I peaked at 57.6psi and 1729* EGT I've seen 1850* on the street

It should act right when I finally get the timing back where it should be, I'm at an anemic 13*, and should be at 17*

As far as I know, I had an Autometer Street Probe. I have a SW Street Probe now, too.

Chris

HOHN

No doubt I need more air

Obviously not as badly as YOU do, lol!


I just got off the phone with Autometer. According to the tech rep I spoke to, the NV series probes (same as Cobalt and C2) are better than the old Ultralite, and not as good as the Competition series probes.


Still, he said even the NV series probe I have is accurate to 2% between 400° and 1600°.

2% at 1000° is only 20°, so I'm pumped.

When asked about response time, he said that the probe can go from 400 to 1600 in less than a second. That's plenty good enough for me.


Maybe my rig is NOT too good to be true!

Why is it that we only trust our guages when the tell us bad news??

RowJ

Assume your refering to the 1100* max egt's in the hot weather with 36 psi boost, mentioned up top?
What SW# is Smarty set on?
Will try mine with TST off, for comparison. Just curious.

The comparison between high altitude, thin but cool, dry air.... vs hot, muggy, sea level air is interesting to me, as to how it affects our trucks.

I remember from my flying days.... the term "density altitude". Basically plug in temp and barometric pressure and it gives you a "performance altitude". Under those specific conditions, the plane will feel like, and perform, as if it were at XXXX ft above sea level.

Maybe "Density Altitude" is all we need to compute for comparing different performance caracteristics between Cheyene and Tampa (for example).

Just thinking out loud.

RJ

HOHN

Yeah, the 1100° is at WOT at 36psi, but only 70mph or so. I have to back out of it for traffic. If I could SUSTAIN wot for a while, I know that it would go a lot higher.

Fact is, when I back out of it, the gauge is like the Jeffersons (movin' on up)-- it's not levelled off at 1100 by any means.

I'll try to find a quick way to convert temp and pressure to density altitude, because I think it's the most meaningful measurement of atmosphere as it relates to boost and EGT.

Smarty's on #9-- ever since clutch went in.

HOHN

Oh, and I found a good density altitude calculator:
http://wahiduddin.net/calc/calc_da.htm

Putting in my Florida conditions gives me a density altitude of 1977 feet (assuming 29.92 altimeter as constant).

In my WY conditions (cold, dry, thinner air), I get 6200+ feet, even in cold winter air.


A very useful metric from that calculator is absolute pressure: I'm only 24in HG in Wyoming, but I'm 29.86in HG here in FL.

By all "scientific" indicators, I should have a lot higher EGT in Wyoming, which I did.

Perhaps the low altitude and high flow filter account for a big drop in EGTs?\

Interestingly enough, low altitude and colder temps HELP density, but high humidity actually makes it worse. I guess that makes sense-- every molecule of water vapor is NOT a molecule of air..

justin

signature600

More air, yes! More timing, definately. Problem is, until I get o-rings, I can't have both. I could probably get about 70psi with the fuel I have, maybe more with higher timing...but the headgasket won't like both, probably not even with studs

Chris

RowJ

FWIW - I get 30 psi boost! Smarty and MAch 4's only.

RJ