marine intake gains

[basschevy]

how much power will a marine intake gain on a stock 350 vortec? is it worth the $750 to swap it out or do you need to do upgrades such as cam,heads,headers,ect to benefit from it. im planning on doing exhaust and a custom tune thinking maybe the marine intake would go good with the exhaust upgrade and a custom tune. any thaughts, comments? thanks

[ArrivalSS]

I was reading a bit on it last night. There's some good stuff about it. Not sure of big power gains initially, but it utilizes regular EFI injectors, so you can put what ever size injector you need. The power potential is much, much greater. Search vortec intake on this site, and it'll bring it up.

[Pauly]

I dont have hard numbers but power is up from 3800-5800rpm, with no loss of torque anywhere. The stock powerdropoff at 4800+ rpm is gone as well.

Is the $1000 ($750 just gets you the intake, then you need tuning, fuel lines etc)for the swap worth it?? By itself, prolly not, but you cant go very far with the stock 19pph injectors. 340 rwhp is about the max or just north of 400 crank hp.

If you plan to do a cam swap, I really cant suggest it without some sort of aftermarket intake manifold. The stock intake simply wont support the airflow needed for decent power gains. There are lots of guys who ave doine cams and havent beedn happy with teh results.
It just shows that you have to look at engine perfoamncxe as a package deal, no single component will give you huge NA power gains.

peace
PAuly

[Aloicious]

Originally Posted by Pauly

I dont have hard numbers but power is up from 3800-5800rpm, with no loss of torque anywhere. The stock powerdropoff at 4800+ rpm is gone as well.

Is the $1000 ($750 just gets you the intake, then you need tuning, fuel lines etc)for the swap worth it?? By itself, prolly not, but you cant go very far with the stock 19pph injectors. 340 rwhp is about the max or just north of 400 crank hp.

If you plan to do a cam swap, I really cant suggest it without some sort of aftermarket intake manifold. The stock intake simply wont support the airflow needed for decent power gains. There are lots of guys who ave doine cams and havent beedn happy with teh results.
It just shows that you have to look at engine perfoamncxe as a package deal, no single component will give you huge NA power gains.

peace
PAuly

Hey Pauly, in your sig it says you've got 29# injectors, did you change from the 24# ones you were running for any particular reason? also have you noticed any reliability/driveability issues since you've had the intake for a while? did you ever figure out that possible puddling in very cold weather issue that you mentioned in the marine thread over at PPE?

I ended up getting 350SS's aluminum MPFI setup from over at the PPE forums, and I'm just interested in anything people have run into since doing any MPFI swaps.

Thanks Bro!

[Pauly]

I have the same 24 pph at 43.5 psi or 29pph at the vortecs 60 psi of fuel pressure EV6 injector with teh USCar connectors. I just say they are 29 pph injectors because that is indeed what they flow at 60 psi of rail pressure. I dont ever run 43.5 psi of pressure.

I still have the puddling issues when the engine is stone cold in teh winter time and only at low TPS and engine revs. I need to adjust my VE tables slightly. I beleive it to be a tuning issue. en the engines warm all is good.
And since I have an iron intake on iron heads, I havent had to do a set of intake gaskets.

OH wow, that intake you have is an awesome peice, you will LOVE that.
peace
PAuly

[Aloicious]

Originally Posted by Pauly

I have the same 24 pph at 43.5 psi or 29pph at the vortecs 60 psi of fuel pressure EV6 injector with teh USCar connectors. I just say they are 29 pph injectors because that is indeed what they flow at 60 psi of rail pressure. I dont ever run 43.5 psi of pressure.

I still have the puddling issues when the engine is stone cold in teh winter time and only at low TPS and engine revs. I need to adjust my VE tables slightly. I beleive it to be a tuning issue. en the engines warm all is good.
And since I have an iron intake on iron heads, I havent had to do a set of intake gaskets.

OH wow, that intake you have is an awesome peice, you will LOVE that.
peace
PAuly

Ah, the fuel pressure, gotcha...so is there any pros that you've seen in running the EV6 injectors over the regular EV1? I know the marine injectors are stock EV6 and they have a different connector, but aside from that I didn't know if there was a reason to run one over the other...

yeah I'm pretty stoked about the intake and Max has been a big help with all my questions. but I'm sure there's more to come. I'm going to try and do the 411 swap and the newer 26918 springs in the next couple weeks depending on the weather, and then I'll do the intake in March along with a ZZ4 cam with a couple other things. With the Adjustable FPR on mine, I'm thinking about running the 24# injectors at like 50psi or close, slightly less than stock vortec pressure, I would hope it would help ease a little stress and lengthen the longevity of the fuel pump, since I just had it replaced like 1-2 years ago.

So I know some folks were thinking the puddling you were referring to was actually the motor running lean due to better airflow of the marine intake. did you ever try enrichen it a little for a few days in the cold and see if that helps?

anyways, you're posts have been a big help in my research on all this, so thanks for the help!

[ArrivalSS]

Edelbrock had a system that would convert TBI to MPFI, and I thought they had a setup for the Vortec engines. Maybe not. Would a setup like that work, as opposed to the marine intake?

[Pauly]

Originally Posted by Aloicious

Ah, the fuel pressure, gotcha...so is there any pros that you've seen in running the EV6 injectors over the regular EV1? I know the marine injectors are stock EV6 and they have a different connector, but aside from that I didn't know if there was a reason to run one over the other...

yeah I'm pretty stoked about the intake and Max has been a big help with all my questions. but I'm sure there's more to come. I'm going to try and do the 411 swap and the newer 26918 springs in the next couple weeks depending on the weather, and then I'll do the intake in March along with a ZZ4 cam with a couple other things. With the Adjustable FPR on mine, I'm thinking about running the 24# injectors at like 50psi or close, slightly less than stock vortec pressure, I would hope it would help ease a little stress and lengthen the longevity of the fuel pump, since I just had it replaced like 1-2 years ago.

So I know some folks were thinking the puddling you were referring to was actually the motor running lean due to better airflow of the marine intake. did you ever try enrichen it a little for a few days in the cold and see if that helps?

anyways, you're posts have been a big help in my research on all this, so thanks for the help!

The EV6 injectors have tighter tolerances than the older design EV1 injectors. I have seen blueprints for each injector type.

the stock Marine FPR runs at 60 psi with low engine vacuum(WOT) and 50 psi at high engine vacuum (idle, cruise).

The pumps were designed to run at that high of a pressure, but I'm not going to say that pump life wouldntnt be lengthened, I just dont know. I also dont know if its worth the cost of an adjustable FPR that will be needed to run the 50 psi, an AFPR from a 97-98 will work, although I have heard that they will result in a 43 psi rail pressure, but that would still work.

With headers and high flow exhaust I wonder if the huge split that the ZZ4 cam has is really needed. 208/221 is a big split. I really like the Lingenfelter 213/219 cam on a 112 LSA with .493/.502" lift (1.6 rockers)which will work awesome with your 26918 springs and 787-16 (non GEN3 valve diameter) retainers that will allow the Beehive or LS6 spring usage.
http://www.lingenfelter.com/store/lpe-74216.html
I just figure I might as well take advantage of teh higher flowing intake with a slightly more agressive cam tahn the ZZ4. If I had a Vortec 305, the ZZ4 cam would be more of an option in my book. Not to say that the ZZ4 cam wouldnt work well, but I just hate doing things twice.

I think that with some VE tuning I would eliminate my cold idle issues. Whether its lean or rich I dont know, it feels like its rich. ANd I know the marine intakes injector placement isnt as perfect as the stock truck intakes, simply because the stock poppet hoses can be aimed much easier than a normal fuel injector simply due to the fact that the normal injector must use a fuel rail, the stock poppets do not. he marine injectors point toward the floor of the intake runners moreso than the stock truck injection.

I havent tried messing with my VE tables yet, havent had time lately.

Good luck with your swap.
peace
Pauly

[Pauly]

Originally Posted by ArrivalSS

Edelbrock had a system that would convert TBI to MPFI, and I thought they had a setup for the Vortec engines. Maybe not. Would a setup like that work, as opposed to the marine intake?

They dont not make a CSFI to MPFI conversion kit for teh Vortec trucks.

peace
Pauly

[Aloicious]

Originally Posted by Pauly

The EV6 injectors have tighter tolerances than the older design EV1 injectors. I have seen blueprints for each injector type.

the stock Marine FPR runs at 60 psi with low engine vacuum(WOT) and 50 psi at high engine vacuum (idle, cruise).

The pumps were designed to run at that high of a pressure, but I'm not going to say that pump life wouldntnt be lengthened, I just dont know. I also dont know if its worth the cost of an adjustable FPR that will be needed to run the 50 psi, an AFPR from a 97-98 will work, although I have heard that they will result in a 43 psi rail pressure, but that would still work.

With headers and high flow exhaust I wonder if the huge split that the ZZ4 cam has is really needed. 208/221 is a big split. I really like the Lingenfelter 213/219 cam on a 112 LSA with .493/.502" lift (1.6 rockers)which will work awesome with your 26918 springs and 787-16 (non GEN3 valve diameter) retainers that will allow the Beehive or LS6 spring usage.
http://www.lingenfelter.com/store/lpe-74216.html
I just figure I might as well take advantage of teh higher flowing intake with a slightly more agressive cam tahn the ZZ4. If I had a Vortec 305, the ZZ4 cam would be more of an option in my book. Not to say that the ZZ4 cam wouldnt work well, but I just hate doing things twice.

I think that with some VE tuning I would eliminate my cold idle issues. Whether its lean or rich I dont know, it feels like its rich. ANd I know the marine intakes injector placement isnt as perfect as the stock truck intakes, simply because the stock poppet hoses can be aimed much easier than a normal fuel injector simply due to the fact that the normal injector must use a fuel rail, the stock poppets do not. he marine injectors point toward the floor of the intake runners moreso than the stock truck injection.

I havent tried messing with my VE tables yet, havent had time lately.

Good luck with your swap.
peace
Pauly

Hmm, I might have to try some EV6's someday and see how they compare. as for the AFPR, 350SS actually included the aeromotive vaccum referenced fully adjustable fuel regulator with the intake, so I'm set to go. I figure I'll run it at 50ish and if it looks like I need more fuel, I'll up the pressure to 60 or so, but I'm not boosted or anything so I think I'll be okay.

Despite my headers and catback, I've just got stock heads (never been off since the truck was made :) ) so there's no porting or polishing going on there, and I still think my exhaust could use the help, I'm only running shorty headers, so they are better than the stock manifolds, but nothing like LT's, and I still have the stock cats in place, the slightly larger diameter catback does help, but I think it will like the larger duration of the ZZ4, but I'll have to look into that ligenfelter cam though, it sounds like a good setup as well and I didn't find that one while I was doing most of my research for the swap, that may be a good option as well.
EDIT:I'm still running the stock TQ converter as well and will be for a little while.

I'm sure you'll be able to get the VE down right at some point. Its probably just a little bit harder to pinpoint it using TC than having the help of AutoVE with EFILive. but it sounds like you're still running well with the marine.

[Aloicious]

Originally Posted by Pauly

They dont not make a CSFI to MPFI conversion kit for teh Vortec trucks.

peace
Pauly

So, sorry for derailing this thread. there are other options besides the marine intake to convert the L31 to MPFI, such as the ramjet 350, or custom modified carb-to-vortec heads intakes like the Edelbrock Victor Vortec intake (I think that's its name)
here is the intake that I have been talking to Pauly about, I am preparing to put it on my '96 L31, along with several other mods:

(the pic is actually from the fellow I bought it from who had it on his 383, hope he doesn't mind me using this picture of it.)

It is basically a GMPP TBI intake that mates up with Vortec heads, it was modified for MPFI and to accept the stock Vortec Throttle body and all regular emissions stuff like EGR and EVAP.

although, if the one I got wasn't already modified and setup to go on a L31 prior to me getting it, I would have gone with the Marine intake, because if starting from scratch, it would cost more to modify and make it work, than it would be to do the Marine setup with its modifications.

So there are other alternatives to the Marine intake, but despite its somewhat large cost, it is actually one of the more affordable options out there for curing the L31's fueling problems.

In answer to your original question, the stock intake will probably do just fine for you if you're only planning on a custom tune and exhaust setup (that is somewhat my setup at the current time) but even with just minor things such as a tune and exhaust, the marine will still help, I just don't know if it's worth the price at that point....however if you plan on doing mods like a cam, heads, boost, whatever, at any time in the future, a MPFI intake WILL be able to let the engine breathe better and be able to fuel it correctly, where as the stock 19# poppets, and poorly flowing stock intake, will not be able to do it very well, and in turn your HP and TQ will suffer, and possibly the driveability and longevity of the engine (a larger need for fuel + limitations of stock intake = lean conditions).

EDIT: spelling

[the_husk]

Originally Posted by Aloicious

So, sorry for derailing this thread. there are other options besides the marine intake to convert the L31 to MPFI, such as the ramjet 350, or custom modified carb-to-vortec heads intakes like the Edelbrock Victor Vortec intake (I think that's its name)
here is the intake that I have been talking to Pauly about, I am preparing to put it on my '96 L31, along with several other mods:

(the pic is actually from the fellow I bought it from who had it on his 383, hope he doesn't mind me using this picture of it.)

It is basically a GMPP TBI intake that mates up with Vortec heads, it was modified for MPFI and to accept the stock Vortec Throttle body and all regular emissions stuff like EGR and EVAP.

although, if the one I got wasn't already modified and setup to go on a L31 prior to me getting it, I would have gone with the Marine intake, because if starting from scratch, it would cost more to modify and make it work, than it would be to do the Marine setup with its modifications.

So there are other alternatives to the Marine intake, but despite its somewhat large cost, it is actually one of the more affordable options out there for curing the L31's fueling problems.

In answer to your original question, the stock intake will probably do just fine for you if you're only planning on a custom tune and exhaust setup (that is somewhat my setup at the current time) but even with just minor things such as a tune and exhaust, the marine will still help, I just don't know if it's worth the price at that point....however if you plan on doing mods like a cam, heads, boost, whatever, at any time in the future, a MPFI intake WILL be able to let the engine breathe better and be able to fuel it correctly, where as the stock 19# poppets, and poorly flowing stock intake, will not be able to do it very well, and in turn your HP and TQ will suffer, and possibly the driveability and longevity of the engine (a larger need for fuel + limitations of stock intake = lean conditions).

EDIT: spelling

Just how do you modify the other intake, tap it for injectors? How do you get the vortec throttle body to fit?

[Aloicious]

Originally Posted by the_husk

Just how do you modify the other intake, tap it for injectors? How do you get the vortec throttle body to fit?

well, I didn't do the modifications. the guy I bought it from had it done by Hotrod Solutions. they can be seen here:
http://www.hotrodsolutions.net/IntakesEFI.html

from the looks of it, he drilled and welded in some inserts into the manifold to accept the injectors, bored out the area that the TBI TB bolts to, welded on a brick of aluminum and drilled it to accept the Vortec TB, plus several other welds and various modifications to accept things like the throttle cable bracket and other pieces. then there is a 1" TB spacer that is mounted which has been drilled/tapped to accept the PCV inlet and EVAP stuff. but again, I didn't do all this so I'm not sure how he went about it and all the little things that were done. Here are some pics I have from the modification process of it.





This is why I say if all this wasn't done prior to me getting it, I probably would have gone with the marine setup. It needs less modifications and is less expensive (when you factor in the cost of modifying the aluminum manifold and everything). But the aluminum manifold is significantly lighter than the cast iron marine intake, and by using the GMPP manifold, like mine, it retains the stock EGR setup, whereas the marine needs to use a divorced EGR which takes a little more to get going. But either route you go will get a great flowing MPFI manifold that will be able to fuel any needs the engine has.

incase people don't know, here is a link to the marine intake thread that goes over all the details of it:
http://www.pacificp.com/forum/viewtopic.php?t=317

[the_husk]

Ok, what are you having to do to your computer if anything for the conversion?

[Aloicious]

Originally Posted by the_husk

Ok, what are you having to do to your computer if anything for the conversion?

Computer definantly needs to be tuned if you're going to use bigger injectors, I'm going with 24# injectors and probably going to run them at 50psi, which will raise them to like 27# or close. the manifolds also have much better airflow, and to get everything running optimally, then the VE (volumetric efficiency) tables in the tuning need to be adjusted a little bit. which is what Pauly and I have been discussing a little.

In my case I am also swapping out my blackbox PCM for a 12200411 PCM, then I am going to tune it myself with a program called EFILive to get it just how I want. here is a link to a thread detailing the swap of the stock blackbox PCM with the newer LSx style 411:
http://www.pacificp.com/forum/viewtopic.php?t=3240

The computer swap is not a necissity though. Pauly still uses the stock blackbox computer with his Marine intake and originally had it tuned by Ed Wright I believe (I don't know if he just had it as a mail order tune or not). He now tunes it himself with a program called Tunercats. so if you want to keep your stock computer, you could get a custom mail order tune to have the injector flow changed and any other changes you want. or you could tune it yourself. however the only programs that I'm aware of that support the '96-'97 blackbox PCM's are Tunercats (which sold its rights to JET, although it is still available only with the purchase of a roadrunner from Moates, Pauly can provide more info on TC than I can if you're interested), or JET DST.

I opted for the 411 PCM swap due to the fact that it has more tuning options and abilities than the stock blackbox as well as more support from tuning suites. plus the 411 swap is relatively cheap, with all the parts running only around $100-120 total.

[acethedragon]

i actually did the conversion on my '96 tahoe using the edelbrock tbi to mpi vortec kit. had an elbow to adapt stock tb to the intake made by a friend. everything else was pretty easy. ran great. will go holley stealth ram next time around.