Holy Temperature Batman!!!

[roadhawg]

I drilled and tapped my exaust manifold this morning.

I've been running with my piro mounted post turbo for 5 1/2 years.

Everthing was fine untill I took it for a spin. The first time I had some space in front of me I rolled into the throttle in 5TH gear It pegged the needle at 1500

:--)

I slowed down again, checked the radar detector and nailed the throttle again.

1. boost goes right to 40+

2. speed climbs to 90 maybe 3 seconds

3. as speed climbs near 90 piro peggs at 1500 and stays there while decellerating back down from 100MPH!

I had no idea the temp was ever getting that high. Thats over 550 degrees differential between pre and post turbo mounted piro locations!

Whats worse is that I just finished installing a ford intercooler to help get rid of some of the smoke. No telling what kind of temps the old truck saw before the swap

I think twins are in my future

 

[Dieselman359]

Fun Run

Here's one ya'll 'ought to get a kick out of. Ever since I got my GV in I run down the highway @ 75-80. At that speed the temp stays around 600-900. So I thought that if I adjusted the timing like all of the recent talk suggests, I would perhaps lower the EGT's a little. I moved the pump a little, but not much and went for a spin. I didn't notice much of a difference, I guess that I'll move it some more, time permitting.

Anyway, enough of my ramblin' and on to the story I passed a newer Mustang at about 80mph, and noticed him gaining some speed, so naturally I hammered down Anyone from Missour knows about Antire hill on I-44, I don't know the exacts, but its steep. Anyway I looked down and saw 100mph on the speedo 1100 EGT and about 28psi, not to mention a little smoke out the pipe (I'm working on that Power Wagon)

Well I had a smile on my face when I saw the Mustang tryin' to catch up

 

[BushWakr - RIP]

... "It pegged the needle at 1500 "







Informative aint it !!!!!!! That about explains how I felt after I moved my pyro too.

Piers didn't help when he said..... " 1250*F all day long no problem..... 1350*F 1 minute out of 5... ..... 1500*F 30 seconds to Chernobyl time... . "

Timing will help a bit, but don't expect miracles.



Regards, Bob.

 

[paccool]

OUCH!! Sounds like I better move mine to the pre turbo location as well. I don't see anything over about 950 post turbo even going up hill pulling the travel trailer and felt I was ok but I'm not so sure now.

 

[roadhawg]

Hey Bob,

What do you do to the timing to help with temperature?

Eric

 

[BushWakr - RIP]

As I understand it advancing the timing helps with smoke, EGT's, and improved throttle response. If advanced alot, it can reduce a bit of power on the low end in exchange for better mid/high power. I saw a small reduction on the low end, but nothing I'm really missing to be honest.

The more common timing being run in our trucks seems to be between 14*advance and 15. 5*advance with some fellows (nascar mark for example) running as high as 17*advance. (about 1. 5mm)

Increasing advance over stock settings (usually around 1. 25mm lift or 11*?) is applicable especially if you've installed larger injectors like the 180's, PW's or POD's (Lucas) nozzles.

Those injectors have a higher "pop-off" pressure and as a result, have the effect of retarding timing.

If you advance timing you will raise cylinder pressures.



paccool,



I know what you mean too... . I was using that formula to "do the math" when my pyro was post-turbo. To be honest I mostly got tired of adding and multiplying so I had it moved. Damn glad I did.

I did see proof of something Piers told me, and that was that as the boost #'s go over about 20psi the formula goes "in the can" as far as accuracy.

If you look at roadhawg's numbers, you'll see that he quotes ... " 550*F difference between post and pre-turbo readings.

1500* - 550* = 950*F

The formula generalizes that for every 1 lb of boost you add 10*F to your post-turbo reading.

Based on that formula, in order for roadhawg to hit 1500*F pegged he would have to be running 50psi boost or more to see that reading. :--)





Right now I'm getting about 25/26psi out of mine. When I lean on it real hard in OD, up a grade (about 9/10%) for 1/4 mi. I'll hit around 1100*F.

Post-turbo is great for cool-down readings though, since the the inlet side of the housing will cool quicker than the exhaust side.

So... . let the pyro drop well below 300* before shutdown (pre-turbo) since the other side stays warmer longer.



Ps: if anyone see's errors in this PLEASE post corrections for all of us to learn from.

 

[paccool]

This is a good topic guys. Lets keep it going and see what else comes out of it. Does anyone have dual pyros with one before and one after? 550 degrees difference in a distance of 6" or so sure seems like a lot! Hard to vision what would make it change that fast. Is it because the exiting air is allowed to expand after the turbo?



Does anyone know what the air velocity is going thru the turbo area? CFM is one thing, velocity is another. I don't know the area in the turbo so converting CFM to velocity would be hard to do.



Stan

 

[roadhawg]

I think the reason for the wide range is my fault! I'm a MOPOWER kind of guy, so when we put the 4" exaust on I insisted on making the transition as close to the turbo as possible so when it came time to weld the bunghole for the piro it was in the 4" elbow only about 2 1/2" from the turbo but the hot air had lots of room to expand. So in my attempt to have as little backpressure as possible I could have cost myself the engine and the only reason that didnt happen is LUCKOo. Oo. Oo.

I advanced the timing and still peg 1500 so I'm probibly going to do something drastic like twins.

I've got a big turbo off a johndeer tractor sitting here.

Happy bombing! Eric

 

[BushWakr - RIP]

In a post-turbo mount situation, the closer to the turbo outlet you are the better in terms of accuracy. The further from the housing outlet you get, the wider the variance you'll see, IF I understand it correctly.

The reason there is a wide range of temps is that the exhaust is hottest as it enters the turbo. That heat energy is dissipated (transferred to the housing) somewhat in it's effort to spin the pinwheel. So you see higher temps at entry, and lower temps at exit.

On shut down, once again, the exhaust is now cooler going into the housing since there is no more "load" generating hot exhaust.



(did you notice the speed with which the pyro responds on a pre-turbo mount compared to post-turbo???... the delay is much less. On a post-turbo mount it takes more time since the heat is being taken by the housing before getting to the probe)



This "cooler" gas shows up on the pyro almost right away.

It does not show up so quickly on the outlet side since the exhaust flow through the housing is now having to carry away the accumulated heat in that heavy casting.

In order to make sure you don't "coke" the turbo bearing you need to let it cool a little longer so the built up heat is reduced.

If you go by the pre-turbo pyro on cooldown, you'll see say..... 300*F but post-turbo you might actaully have 350* - 400*F or whatever.

Again, thats how I understand it and I'm willing to be corrected.

I never shut down with any temps higher than about 250* pre-turbo.