twisselman1968

iTrader: (1)

So I've noticed that I've got a lot of heat under my hood and after coming home Saturday night when I opened my hood my manifolds were glowing bright red. My setup is pretty basic, truck manifolds turned around with 2 1/2 inch union pipe to a t4 flange then thru a eBay 76mm then mandrel bent three inch down and out the side. The motor is a 4.8 with gapped rings fresh rebuild, Asa Cam and fresh heads with 918's. Running down the highway I'm turning about three thousand rpm's and usually between fifteen and twenty inches of vacuum while cruising down the road. So is glowing manifolds normal? If not where should I start?

coltboostin

Who tuned it? Sounds like your timing is a bit low in that part of the map.

twisselman1968

iTrader: (1)

I've got a friend in town doing my tuning, we're both pretty new to the turbo side of things and I now know that his turbo car does the same thing and our setups are almost identical other than cams. I'll get with him tomorrow and see where the timing is while cruising.

SUPERMAN_00TA

iTrader: (25)

It has to be extremely lean for that to happen.

twisselman1968

iTrader: (1)

I'm running in the low to mid thirties timing while running down the highway and I'm running in closed loop and the narrow band and wide band are dead on each other.

chiaj144

iTrader: (4)

Have you verified your timing? I saw this happen once and the cam was installed a couple of teeth out.

twisselman1968

iTrader: (1)

Yes The cam timing is good I can guarantee that, and the motor runs great other than the manifolds way hotter than I expected them to be for just driving around

Old Geezer

iTrader: (3)

How about your "tuner" friend and you, get together, and post up a couple data logs and the tune file??

redhotev1

iTrader: (5)

3000 rpms and ebay t4 turbo, yep. Get used to it.

Measure backpressure in exhaust stream during cruise, you'll be supprised.

Mine does it, I can see it at night.

twisselman1968

iTrader: (1)

I'll try to get him to post the tune on here and the last couple data logs

Tanus

if you a/f is good, and your pre turbo sized and configured properly you might wanna make sure the turbo is still spinning freely, also maybe the a/f meters are positioned in a spot giving you a false reading? oh you may just be lean at cruise rpms, but good under boost and idle. otherwise fatten it way up and see if it goes away, beware of boost, haha

just giving you some ideas

busta9876

iTrader: (3)

My car was doing same thing, still does to some extent, after all we do have insulation wrap over the entire hot side.

Attached is the tune from my car on dyno back in Feb, and the datalog is a few weeks prior when I was still doing some drive ability tuning. AFR on dyno was rock steady 11.4 to 11.8 to 1 entire pull. 443 rear wheel horse corrected. 9 psi 17 degrees timing, stock 5.3l. The setup on this log only shows narrow band sensor, no wide band was hooked up. Also, ignore Bank 2 fuel trims, all 8 injectors are set to fuel off bank 1. (single bank fuel control)

Power enrichment settings are set up based on throttle position (under 100kpa) and there is a boost enrichment that comes in at 100 kpa. My car starts to build boost around 27-30% Cruising down the highway was usually under 20%, so any tip in on throttle, climbing hills on highway, would result in power enrichment. (see cold power enrich tables)

timing on my log showed around 39-42 degrees cruising. I do have over drive on my car, so rpm is lower at cruise speed.

I am running a Precision PT6766 turbo, might be a bit small on the exhaust side, but very fun to drive (which is its primary purpose) It is daily driven...

busta9876

iTrader: (3)

And now the tune and log from John's truck (original poster of this thread)

we started out with same tune I was running and made changes to it. We have identical fuel systems, injectors, regulators, everything. He's 4.8, I'm 5.3L. He has an ASA cam, and I have a TU0 cam. He is TH350 3.73 gears, I have 4L80E with 4.10 gears.

His truck has a dakota digital speed sensor on the cable output of the th350, so the speed reading is kind of erratic. His wide band is hooked up and functional for data logging, but its in open loop in this log. Using same PE set points as my tune from before. There is NO LONG TERM fuel trim enabled, only short term, so it is completely OPEN LOOP in power enrichment with no long term correction applied.

for some reason the log on his truck, the histogram only shows the spark going to 0.52 gram/cyl I know the airflow was much higher at times...I see this time to time on HP tuners logs...don't know why it does not read right. The log from my car shows much higher airflows....odd...

Sarg

iTrader: (6)

Check timing at idle and IAC count while idling.

123quattro

A non-firing cylinder will also make things really hot really fast. Granted, you should see that in the wideband. And you'd need one on each side to get both manifolds glowing.

twisselman1968

iTrader: (1)

I don't think it has any misfires going on, it's smooth and throttle responsive at all times, I'm going to try to but a drive pressure gauge in it and see what the drive pressure is like