Vortec L31 MARINE MANIFOLD project! Q&A

Tahoe.mkIII · Post by **Tahoe.mkIII** » Thu Apr 16, 2015 7:43 pm

greetings ladies and gents.got the intake powdercoated last week and getting ready for the install.couple questions first though.2000 tahoe.L31.whipple...
if im not using the egr, think i could use the egr port for a boost sensor?
any cons to placing an IAT sensor in the large boss in the center of the manifold and placing a 1/4npt x 3/8 hose in the small boss at the rear of the manifold which will go to a separate vacuum block/manifold mounted on the firewall for evap, pcv and brake booster.
any flaws in this logic? thanks

also.kudos to all you folks that have experimented, succeeded, created and compiled this ginormous chunk of data

Post by **James B.** » Fri Apr 17, 2015 11:14 pm

Hello, thank you, and Welcome!
If you don't need EGR then buy all means use the port for anything you like. A lot of these manifolds came with a small vacuum port adapter installed in that port. Some were plugged. I would think drilling and tapping the EGR port plug would work - it is steel.

Tahoe.mkIII · Post by **Tahoe.mkIII** » Wed Apr 22, 2015 6:58 pm

excellent.thanks james

Toclcl · Post by **Toclcl** » Wed Apr 29, 2015 12:51 pm

Still looking for a supplier on the west coast if possible. Thanks in advance
Todd

coco524 · Post by **coco524** » Mon Jun 08, 2015 7:55 pm

Well hello everyone. Iam new to the group.

Just picked up a marine intake but was wanting to know how bad is the
Coolant bypass to drill and tap??

Thanks james

Hog · Post by **Hog** » Tue Jun 09, 2015 7:21 am

coco524 wrote:Well hello everyone. Iam new to the group.

Just picked up a marine intake but was wanting to know how bad is the
Coolant bypass to drill and tap??

Thanks james

Welcome to the forums. Congrats on your new upgrade, the marine intake helps with many of the stock CSFI's intakes shortcomings.
I got my Marine Intake as part of the first group which came drilled and tapped by Pecos himself, sorry I cant help you with that. I was lucky enough to get one of Pecos' install kits as well.

Again welcome to the Pacific Performance Engineering truck site, and keep us updated on your progress.

peace
Hog

stroker97k1500 · Post by **stroker97k1500** » Tue Jun 09, 2015 8:58 am

coco524 wrote:Well hello everyone. Iam new to the group.

Just picked up a marine intake but was wanting to know how bad is the
Coolant bypass to drill and tap??

Thanks james

It's not that bad to do. Just guesstimate the angle (I made mine go from the center of the pad down into the center hole from memory) just purchase a bunch of drill bits and take your time and go up one size at a time. Then tap it. If you didn't make it into the center hole I done thing it will matter much either.

coco524 · Post by **coco524** » Tue Jun 09, 2015 9:04 am

And it needs to be tapped to 3/8 also?

What's the best way to make sure it is close to center?

pcking · Post by **pcking** » Thu Jul 09, 2015 12:05 pm

Greetings - newb to this forum but almost 30 years of wrenching and racing.

For my tow vehicle, I have a 406 SBC that I want to install - its a '99 Suburban who's stock 350 spun a bearing and even before that always struggled to pull my trailer up any sort of incline.

I feel that in order to feed the extra displacement (nearly a whole liter) that I need a better intake, better injectors, etc. but need to pass NYS emissions So, I want the Marine Intake but have had a tough time finding one. Someone just put a complete unit up on EBay, but they want $1199 for it and that seems a little steep and I am not totally convinced it od the correct part.

http://www.ebay.com/itm/400944647604?_t ... EBIDX%3AIT

The rest of the engine has had no expense spared including forged pistons, pink rods, line bore/hone, balanced reciprocating assembly, etc. I even added Edelbrock E-TEC heads which are higher performance version of the vortecs cast in aluminum, as well as a beefier cam and high-end valve train. I want to build something I can count on for the next 150-200K miles and be able to tow my trailer up Everest if needed...

Despite living on Long Island, I have not been able to find any decent deals - in fact, aside from the unit I found on EBay, I cannot find any L31 Marine Manifolds anywhere. A friend told me that maybe they were still too new and therefore not as many of them being junked and sold, but I must be doing something wrong here.

Any tips are welcome - I need to get this baby installed by the end of this month if at all possible. Rest of the engine is ready, so I can start the rip and replace the day after I get the intake.

If you are looking to sell one, know where once can be had for a reasonable price, etc - PLEASE PLEASE PLEASE hit me up ASAP.

Thanks in advance! -Phil

SunlitComet · Post by **SunlitComet** » Thu Aug 13, 2015 11:51 am

Looking at the corrosion on it i would not touch it and definitely the price is way to high. If in better condition i would maybe offer maybe $200 for it. It is just not that popular anymore. I would probably keep the original and search in the meantime for a used Whipple sc kit. I have seen them as high as $1500 for a complete kit but you are looking at an automatic 50%+ increase in power. The marine intake at $1200 can't do that at all. And it is all street legal in any state.

yukondad · Post by **yukondad** » Thu Oct 01, 2015 5:28 am

Hello- Long time lurker, first time poster. Let me say that this thread has been AWESOME to read through and there are some pretty sharp fella's on this board! I wish I knew half of what most of you have forgotten...

Anywho, I have a 1997 GMC Yukon that's pretty much stock that I daily drive. It's got 218k miles on it and runs pretty good for it's age. After reading though this entire thread over a number of days, I went search to find an L31 Vortec 350 Marine Manifold that you guys' talk about in here. Took me a while, but I did find a peach of a kit, as it was a new take-off from a Mercruiser engine from a local marina. I was stoked, but that was a year ago and my truck is still stock... I've come to the realization that what I want to do to my SUV exceeds my ability to do so and my time is at premium with a family and all... I.E.- I'll probably never get this done to my truck...

Does anyone have an interest for this for their project? I was going to post it on Ebay, but I figured I post it here first since you guys know more about this than most folks probably do. I've seen them go for over $1000 bucks, but I think that's a bit steep.. What is a fair price for this thing these days and is there anyone interested in it? I want to be fair to the seller, as well as, the buyer.

Hopefully someone can use it constructively and I guess I'll have to live vicariously though you guys' awesome builds until I gain some mechanical experience of sell off part of my family to afford me more time.. lol I have pictures and I can be reached on the phone if need be.

Cheers!
Jon

snapperpirate · Post by **snapperpirate** » Sun Nov 08, 2015 12:13 am

Does any one else have one for sale please let me know !

Hog · Post by **Hog** » Fri Jan 15, 2016 7:37 am

Brand new complete 3 bolt t-body upper plenum intakes for $1479.
http://www.michiganmotorz.com/cast-iron ... p-486.html

Brand new complete 4 bolt t-body upper plenum intakes for $1199
http://www.michiganmotorz.com/mercruise ... -4576.html

peace
Hog

Hog · Post by **Hog** » Mon Mar 21, 2016 8:26 am

Michigan Motorz now sells 3 types of intake manifolds, the newest one is only $799

This one uses the 4 bolt throttlebody, and its only $799, this manifold is USED

http://www.michiganmotorz.com/mercruise ... -9591.html

This one also uses the 4 bolt t-body for $1,199

http://www.michiganmotorz.com/mercruise ... -4576.html

This one uses the direct fit 3 bolt t-body.

http://www.michiganmotorz.com/cast-iron ... p-486.html

Let it be known that all 3 of these upper plenums are interchangeable between these intakes, meaning you can buy a 4 bolt t-nody upper/lower and swap out the upper plenum for a 3 bolt t-body upper plenum.

peace
Hog

Whipped383 · Post by **Whipped383** » Mon Mar 21, 2016 6:01 pm

The first one listed has fel lines pointing forward. Wonder if they flip around

Hog · Post by **Hog** » Mon Mar 21, 2016 6:48 pm

Whipped383 wrote:The first one listed has fel lines pointing forward. Wonder if they flip around

Looks like they just threw it on backwards for the pic.

peace
Hog

alsolek96 · Post by **alsolek96** » Tue Mar 29, 2016 7:24 am

Just a few questions. Can the truck manifold fuel pressure regulator be used in place of the marine? Also if anyone has the part number for the 2 bar map sensor if would be appreciated.

97VortecChevy · Post by **97VortecChevy** » Fri Apr 08, 2016 10:05 am

As many people that look for these or in need of these I sure would've thought someone would be buying these things up and making them ready for install and selling them!!

Speeder · Post by **Speeder** » Fri Apr 08, 2016 4:25 pm

That's been tried, but the demand wasn't there. Folks now are looking at putting LS engines in their Vortec trucks.

Hog · Post by **Hog** » Mon Apr 11, 2016 8:03 am

alsolek96 wrote:Just a few questions. Can the truck manifold fuel pressure regulator be used in place of the marine? Also if anyone has the part number for the 2 bar map sensor if would be appreciated.

Two BAR MAP sensors are from any GM V6 3.8 supercharged application. A 5 second look at Rock AUto turns up the US$47.99
09350899, 12580698, 12615136, 2131155, 9350899 for part numbers for a 2004 supercharged 3.8 V6 Impala

Not sure about the stock trucks FPR being used in place of the marine intakes 58psi unit. Not sure why you'd want to, unless you are trying to use some 23.4 lb/hr injectors.

peace
Hog

GM Performance

Vortec L31 MARINE MANIFOLD project! Q&A

Seems like these have dried up

snapperpirate needs one !