Marine Intake

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HotWheelsBurban

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We gassed up before leaving Conroe yesterday, and the needle shows an eighth of a tank down. I didn't fill it(the gas there was pretty expensive) but was close to F when I stopped. The gauge is past the F when it's actually full. That in mind, I didn't want to come home on a quarter tank...at night...even though it's only about 50 miles going the way we went. This truck gets around 10 mpg in town, so we'll see how long this lasts. I didn't unload today, so I'll do it tomorrow between stores....just too tired today.
 

L31MaxExpress

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Yes it does. Adding some open loop fueling really made mine a lot happier. The 454 doesn't even act the way the marine intake does on the 350.

Nearest I can tell I have the Marine manifold completely tamed. Once I discovered my P59 has about 10 different Transient fuel tables and started adding to both the Impact and Boil times as well as added a big chunk to the throttle stomp and decayed out the throttle stomp fuel more slowly. Basically adjusted it to give more transition fuel for a longer period of time. It works in reverse as well though and really cut down on the rich spike letting off the throttle as well. I also made the EOIT Boundary coincide with BDC using a value of 6.5 with a Normal and Makeup table value of 6.3 all across the board. That really helped the lean idle and lean running right after a cold start because it is no longer sucking a large chunk of the warmup fuel directly into the exhaust during the overlap period. Seems that GM used retarded ignition timing and advanced injector timing during warmup to pull raw fuel into the exhaust create a blow torch effect on the cats to warm them up. Having wideband data in the datalog really helped dial all that in.
 

Supercharged111

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Nearest I can tell I have the Marine manifold completely tamed. Once I discovered my P59 has about 10 different Transient fuel tables and started adding to both the Impact and Boil times as well as added a big chunk to the throttle stomp and decayed out the throttle stomp fuel more slowly. Basically adjusted it to give more transition fuel for a longer period of time. It works in reverse as well though and really cut down on the rich spike letting off the throttle as well. I also made the EOIT Boundary coincide with BDC using a value of 6.5 with a Normal and Makeup table value of 6.3 all across the board. That really helped the lean idle and lean running right after a cold start. Having wideband data in the datalog really helped dial all that in.

Yeah I've been wanting to give your thread another read for all the stuff you did to it. I just added flex-fuel to the P59 on my Z06, just need to add a sensor and turn it on. While it won't do much of anything for the car as it sits, it does give me a big reason to P59 swap a truck. I'd love to see how they respond to E85 even though it would be really hard on fuel.
 

L31MaxExpress

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Yeah I've been wanting to give your thread another read for all the stuff you did to it. I just added flex-fuel to the P59 on my Z06, just need to add a sensor and turn it on. While it won't do much of anything for the car as it sits, it does give me a big reason to P59 swap a truck. I'd love to see how they respond to E85 even though it would be really hard on fuel.
Mine is really not that much worse on E85 while I am just cruising around, WOT is a different story. It happily eats another 5-10* of timing under load on E85 than it likes on 93. E85 will also seems to combust at a leaner Lambda than Gasoline. Where gasoline starts to misfire around 1.20 lambda, E85 happily cruises at 1.30 lambda. Station 5 minutes from the house carries E85 at $2.94/gal. 93 is $3.79/gal. It seems a little cheaper to run it on E85 and it makes alot more torque. On E85 I am cruising along at about 12.5:1 air/fuel. 93 octane about 16:1, but with the extra torque I am not in the throttle as much to get rolling and stay rolling. I think your truck would really love it when the IATs are hotter than hades with the whipple.
 
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Supercharged111

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That was my thought, intercooling options are pretty limited and I've gone from non to intercooled before. It makes a big difference, this would be similar.
 

Singlecab

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Hello all. I have sort of caught up on this thread, but a lot of it is focused on tuning, and I’m still a ways from that point. Unfortunately I’m getting unmarried, and took a beating so funds are just not what they once were. I still need coils, headers, and coil mounting stuff, and would rather wait vs throw it all together. My question for today may have already been touched on. I feel like I’ve seen it somewhere but can’t find it. Can I use the 3/8 pipe port on top of the marine intake as my bypass? I had the machine shop drill and tap the factory location of the temp sending unit, but he grimaced at the prospect of drilling through that seemingly huge chunk of iron for the factory bypass location.
 

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L31MaxExpress

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Hello all. I have sort of caught up on this thread, but a lot of it is focused on tuning, and I’m still a ways from that point. Unfortunately I’m getting unmarried, and took a beating so funds are just not what they once were. I still need coils, headers, and coil mounting stuff, and would rather wait vs throw it all together. My question for today may have already been touched on. I feel like I’ve seen it somewhere but can’t find it. Can I use the 3/8 pipe port on top of the marine intake as my bypass? I had the machine shop drill and tap the factory location of the temp sending unit, but he grimaced at the prospect of drilling through that seemingly huge chunk of iron for the factory bypass location.
That cast iron drilled and tapped like butter once I found the nerve to attempt it on my manifold. You could delete the bypass entirely, pop a couple 1/8" holes in the thermostat and have more consistent cooling. Honestly what I should have done in my climate.
 

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So after all this, my 383 is coming apart yet again. SMH. I am not happy at all with the 218/228 on a 108 LSA cam in it after removing the Rhoads lifters. Its gutless down low, idles rough, and is not happy at all much under 2,000 rpm. My fuel mileage is also off about 3-4 mpg from what it was even at 70-75 mph on the highway. It is an overcammed slug without the rhoads lifters taming the cam. Then I had a GM LS7 lifter decide it wants to randomly collapse on cold starts when it is under ~40F. That sealed the deal. I am either going with Howards HRC91174 , Morel 7177s or Summit rebranded Morel 7177s lifters. After playing around with DD2003 and the Pat Kelley DCR calculator I have decided on a different cam. I am going with the Summit Racing 8800. It is a 257/267 @ 0.006, 204/214 @ 0.050, 0.480 lift with 1.6s and 112 LSA on a 111 ICL. It keeps my IVC at 61* compared to my current 61.5* but only has 38* of overlap compared to 61.5*. DD2003 was pretty close on the old setup as a overall power curve. The 8800 should give me 30-40 ft/lbs more down low in the RPM range and make more power all the way to 5,000 rpm with only a 9 hp loss at 5,500. Summit claims it has an Idle-5,800 rpm powerband. Currently DD2003 shows my 383 making 436 ft/lbs @ 2,000, 497 @ 3,000 and 513 ft/lbs @ 4,000. The 8800 shows 480 ft/lbs @ 2,000. 500 ft/lbs @ 2,500. 520 ft/lbs @ 3,000. Then up to 538 ft/lbs at 3,500. If the 8800 smooths out the idle, allows me to smoothly load the engine under 2,000 rpm without misfiring like the current cam, I would settle for the same torque I have now. I know the engine can run smoothly at low rpm and offer much more torque as it ran that way with the Rhoads V-Max lifters in it. 61.5* of overlap has a cool sounding idle but the internal EGR really kills off the low speed performance and mileage. I tried adding a couple degrees of timing to try to compensate for the slower burn of the EGR diluted mixture only to make the PCM pull it right back out as knock retard. Currently I am not even locking the torque converter until 68 mph in 4th gear and unlock it under 65 mph and have my shifts at 4,000+ rpm by 50% throttle and the shifts are at 5,500 rpm from 75% throttle to WOT. The current cam makes the engine want to spin up to make decent power. It currently reminds me of the way the stock 350 felt choking on EGR off-idle on the stock tune that opened the EGR valve nearly wide open just off-idle. EGR valve would open and the 350 would fall on its face with a horrible hesitation trying to pull the weight of the van against the stock torque converter and 3.42 rear gear. I would have to spin the EGR choking 350 almost 1,000 rpm higher to get the same torque, which only ate fuel.
 
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