99 L29 454 build

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Scottm

I'm Awesome
Joined
Aug 24, 2021
Messages
287
Reaction score
220
Location
AZ
HP tuners has a great gen 3 tuning forum with knowledgeable folks in there for speed density tuning too:


I'm not going to worry about SD tuning right now, just wanna keep going on the L31/0411 program. Spark control seems to be an extra level of complication though. Can ignition output through the ecm just be turned off? I'm thinking of just running an Msd dist and 6AL.
 

Supercharged111

Truly Awesome
Joined
Aug 20, 2015
Messages
12,689
Reaction score
15,468
HP tuners has a great gen 3 tuning forum with knowledgeable folks in there for speed density tuning too:


I'm not going to worry about SD tuning right now, just wanna keep going on the L31/0411 program. Spark control seems to be an extra level of complication though. Can ignition output through the ecm just be turned off? I'm thinking of just running an Msd dist and 6AL.

You must be joking. . .
 

Scottm

I'm Awesome
Joined
Aug 24, 2021
Messages
287
Reaction score
220
Location
AZ
Besides the poor flow path, the stock intake is designed with no regard to air temp control. The first pic shows the runner that feeds cyls 2 and 4. Notice how it shares the wall with the damn coolant passage! That makes me sick. I'm going to try to reduce heat infiltration, first by making an oil deflector for the underside of the mani with thin stainless sheet metal. The thermally insulating 2 part epoxy coating arrived, which should add insulation to the manifold. I am going to build it up with several layers in the area of the coolant passage. Of course I want to document any changes, good or bad. I found this 12vdc thermocouple monitor on Omega, part number DP7005, and I happen to have a bunch of new and used thermocouples. I'm going to drill a 1/16" hole in the number 2 runner of the old engine for the tc, and find out exactly how hot the air is. Will there be any improvement with the new manifold? I hope to see a 40 deg reduction in air temp just above the injector.
 

Attachments

  • IMG_1670.JPG
    IMG_1670.JPG
    228.2 KB · Views: 37
  • IMG_1669.JPG
    IMG_1669.JPG
    260 KB · Views: 36

Scottm

I'm Awesome
Joined
Aug 24, 2021
Messages
287
Reaction score
220
Location
AZ
This has been an interesting day. I rigged up the thermocouple monitor to a type J thermocouple and to a 12v ni-mh battery with a small Dean's rc battery connector. I tested the calibration on my stove with a pan of boiling water. Water boils at 212 F at sea level. I'm at 1600 ft elevation, so 211 is probably dead on. If it had been within 3-4 degrees I would be happy. Then I drilled a 1/16" hole in the manifold on the runner to the number 2 cylinder, and siliconed and zip tied the tc in place. I taped the monitor on the dash and went driving. Once the engine was up to full temp, air temp in the runner was right there at engine temp - 175 to 185F. Driving around at light part-throttle lets the air move slowly through the manifold, giving it time to reach full engine temp. What about heavy throttle, when air should flow through quickly?

I hooked up my 12k lb flatbed trailer (3200 lb empty) and headed up I17 north of phoenix to the New River area. It was about 85f mid day, ac on, and going a steady 75 mph up the hill. Runner temp still hovered around 180. I slowly gave it throttle, expecting temps to drop, but it actually rose, to as high as 188f. Maybe low manifold vacuum told the egr valve to dump in exhaust gas, raising the runner air temp. Then I dropped it into 3rd gear (3200 rpm) and gave it full throttle. Finally I saw a drop in runner temp, but only to 153f, and after a few seconds it popped right back up to 180+.

There you have it. I don't think it matters if it's 65 or 115 outside, with a cold air intake system or not, light throttle or heavy. The cavernous L29 intake manifold will heat the intake charge to full engine temp no matter what. It's kind of disappointing, but hopefully the coatings and heat shield will help..
 

Attachments

  • IMG_1673.JPG
    IMG_1673.JPG
    165.5 KB · Views: 22
  • IMG_1674.JPG
    IMG_1674.JPG
    239.9 KB · Views: 21
  • IMG_1675.JPG
    IMG_1675.JPG
    294.2 KB · Views: 22
  • IMG_1677.JPG
    IMG_1677.JPG
    244.6 KB · Views: 22
  • IMG_1683.JPG
    IMG_1683.JPG
    186.3 KB · Views: 22

yevgenievich

I'm Awesome
Joined
Jan 21, 2021
Messages
935
Reaction score
1,509
Location
TX
I wonder on temps inside newer plastic manifolds. Might have to test one.
 

L31MaxExpress

I'm Awesome
Joined
Apr 21, 2018
Messages
5,973
Reaction score
7,679
Location
DFW, TX
Nice work, will be interesting to see the difference. I will say that I flushed out my cooling system on the Express the other day while working on the tuning. Without a radiator, cool water flowing into the heater return and hot water leaving the heater outlet fitting on the intake manifold while blowing air with a big fan into the engine compartment to keep the headers somewhat cool, the intake air temps and the whole engine compartment as well as the whole engine stayed very cool. The composite plastic intake and even the aluminum lower intake stayed extremely cool and I could easily rest my hand on them. Even with the factory van intake hat that sits on top of the throttle body the engine was pulling a ton of airflow without pulling much intake vacuum. I think there is some definate logic to the 120°F thermostat guys use on the marine engines when they tune them. Both the 454 and 8.1 EFI marine guys run the 120°F stats. At 5,200 rpm the 383 is pulling a peak of 390 gms/sec and staying above 93 KPA. With the stock MAF and 3.5" air ducting my 350 was pulling below 90 KPA above 5,000 rpm and about 330-340 gms/sec. Stock Vortec 350 MAF also used on the 454 is restricting a cammed 350 much less a 454.
You must be registered for see images attach
 
Last edited:

yevgenievich

I'm Awesome
Joined
Jan 21, 2021
Messages
935
Reaction score
1,509
Location
TX
What was the difference on temperature between stock iat sensor location and the measured temperature inside the intake manifold?
 
Top