5.7GLI non-vortec repower to a Vortec 5.7L and possibly a 383 stroker.

[Bigdave196]

Currently installed in my 1997 Blue Water Monte Carlo is the following 5.7L 250hp TBI Non-Vortec Volvo motor, SX Drive.
5.7GLI PLKDCE
4110145128
3868732

ECU - 57TBI/97L001 Then something on the side of the TBI reads BCTU 16184069.

Drive unit- SX-C1 1.51 - running a 19* 4 blade Solas Aluminum prop.
4112031506
3868393


I want to do a Vortec re-power and possibly stroke the motor to a 383, and still maintain the TBI. I can replace the TBI with a carb if necessary, but if I do will the Distributor and ignition system work? I understand that I will have to re-flash the ECM for the TBI if I build a stroker motor, but either way I go I will need a new block. Here is why....

Issues are as follows, when I bought the boat 5 years ago, I was unaware of the "Quick-steel/jb welded" repairs done to the external part of the short block on both sides of the block. I took the advise of, "It's not leaking, don't worry about it", and it has yet to fail. The cracks were external and not internal from the previous owner not properly winterizing the block at one point. When the head gasket failed this summer I started plan a re-power because of the hours on this motor which has almost 1100hrs and this boat spends its days pulling tubes, Sea-Sleds, and wake boarding and all the full throttle abuse that comes from it.

With the heads rebuilt and re-installed the motor achieved 4800-5300rpm easily with a 19* 4 blade Solas propellar, before I noticed that there was the water leak from the same side that the head gasket failed. Thats when I noticed that there was a slight water leak between the #3&5 cyl where the head gasket failed. The machine shop says that there is a very good chance that the block has a small crack and that it's very common for that to happen on marine engines. I was the one who tore down the motor and

This is where I need advise/help.

Do I find a new Short block and attempt a 300hp repower and use the same heads that were rebuilt?

Do I re-power with a new block and Vortec heads and find a different intake manifold to use the same TBI, and possibly re-flash the system?

Do I re-power with a Vortec motor, ditch the TBI and use a 600-650 cfm marine carb to achieve 300-350hp? If so, will the ignition/distributor work with out the TBI?

Do I build a 383 stroker, ditch the TBI or Keep the TBI?

ANY and all options and ideas are welcome. Experience goes to the top of the list. Thank you in advance.

Dave.

 

[Scott Danforth]

brand new distributor for a carb'd motor is $250. since your 97 is not a vortec headed motor, its a carry over, from 1995, as the vortec heads were on all new motors built for the GM 1996 model year. that being said, the difference between your non vortec headed motor and a vortec motor is simply the heads and the intake. your 95 block is no differnt than a 97 block

the easiest thing you can do is simply swap the short block with your existing heads and intake, or swap out the long block for a different long block (vortec or non vortec), the ECM will not care

I suggest the following:
Build the 383 stroker with proper pistons and quench
switch to vortec heads and intake
contact one of the many many people out there and reprogram your ECM since you seamed inclined to keep the TBI

 

[Bigdave196]

So, what if I go to a Vortec headed block and change the cam and internal valve train of the motor? Will the ECM notice the minor differences or will I need to re-flash it because of the new cam? If I can save the $600 for the ECM programming software and cable that would make this decision a lot easier.

The current the heads are the 217 Cast 64cc Iron heads, are the vortec heads that much better?

 

[Scott Danforth]

yes, you will need to remap for a different cam.

yes, the combustion chamber on the Vortec heads is good for 30-40hp alone by the increased flow rate, and better combustion shape. if you are building a motor for vortec heads, get the right kidney shaped piston bowls and shoot for 0.041" quench

 

[Tail_Gunner]

You be far ahead of the game using a carb...tbi's are so old there beconing obsolete and you need to check the tbi to make sure its a 454 tbi and not a 5.7....454 throtlle body's have 2 inch bore's do a google parts search for parts you will see for yourself what's left to support that thing..I have one and know all aobut it.

 

[onegreatsteak]

Your old TBI intake will not work on the vortech heads but you can get an adapter for a 4 Barrel intake for the Vortech heads. Just the Vortechs alone will be 30 more Hp if the TBI is re-tuned. There is a lot of stuff on the internet about TBI units. Some problems are lack of fuel injector size but you can up the fuel injection pressure go get the volume for a higher Hp motor. ECU will probably not need retuning with higher fuel pressure compensating for increased air flow. But there is a limit before injectors stick open.

Carburetor will be easier, but the TBI has so much more torque.

Don't use the 454 throttle body it needs more to get it to work than the one you have. You can even get yours bored to the larger size at pretty low cost, still better than the 454 unit.

If you go to 383 watch out for your compression, even with the 350 if you don't have dished pistons already. the vortech heads have small combustion chambers need dished pistons or you will have a 11 to 1 compression ratio needing race fuel.

 

[keith2k455]

Even though I am OK with a carb, I would love tbi and if I had it I would not go back. I understand TBI may have it's own challenges, but the biggest challenge with a carb is that I can't be sure the Admiral will get the motor started every time she needs to.

 

[Bigdave196]

is there an external way to check the TBI to see if it is the 454's unit? From what it is looking like, the best way so far is to do a Vortec head re-power and go to a carb.

 

[onegreatsteak]

If you have all the tbi stuff and it was working you have the correct unit moveing it should not be much trouble. A little extra pressure on the fule should make up for incresed air flow. There is a web site that rebuilds tbi units also modifies them for more flow, just search for them. Try your unit as is on the 383, if it works good see if you can try the mods and make better. Yuo will have to get another intake but the vortech are worth it. If not, plop a carb on it.

​

 

[Tail_Gunner]

Your old TBI intake will not work on the vortech heads but you can get an adapter for a 4 Barrel intake for the Vortech heads. Just the Vortechs alone will be 30 more Hp if the TBI is re-tuned. There is a lot of stuff on the internet about TBI units. Some problems are lack of fuel injector size but you can up the fuel injection pressure go get the volume for a higher Hp motor. ECU will probably not need retuning with higher fuel pressure compensating for increased air flow. But there is a limit before injectors stick open.

Carburetor will be easier, but the TBI has so much more torque.

Don't use the 454 throttle body it needs more to get it to work than the one you have. You can even get yours bored to the larger size at pretty low cost, still better than the 454 unit.

If you go to 383 watch out for your compression, even with the 350 if you don't have dished pistons already. the vortech heads have small combustion chambers need dished pistons or you will have a 11 to 1 compression ratio needing race fuel.

In the marine industry 454 tbi's were used on engine's from 4.3 to 7.4 both merc and volvo they work quite well but parts are hard to come by these day's and will be worse in the future.

 

[Tail_Gunner]

is there an external way to check the TBI to see if it is the 454's unit? From what it is looking like, the best way so far is to do a Vortec head re-power and go to a carb.

Yes measure the venturi's if there 2" across then its a 454 TB.

 

[Bigdave196]

Yes measure the venturi's if there 2" across then its a 454 TB.

Tail_Gunner: I know the pro's and con's of ditching the TBI. Is it worth the swap over to a 600+ cfm carb since the TBI is becoming so obsolete? I have no intentions of replacing this vessel anytime in the next 5-10 years.

 

[Tail_Gunner]

Tail_Gunner: I know the pro's and con's of ditching the TBI. Is it worth the swap over to a 600+ cfm carb since the TBI is becoming so obsolete? I have no intentions of replacing this vessel anytime in the next 5-10 years.

I would say yes i will be pulling my tbi off this winter just to many issue's with alcohol fuel pumps injectors etc..below is a ink of a 383 build think 750 cfm

http://forums.iboats.com/forum/engin...-a-383-stroker

http://forums.iboats.com/forum/engi...383-stroker-winter-project?t=524489&p=5507909

 

[alldodge]

The cfm calculator indicates 646 cfm at 5300 rpm, 609 cfm at 5000 rpm.

 

[Bigdave196]

The cfm calculator indicates 646 cfm at 5300 rpm, 609 cfm at 5000 rpm.

So get a 650 cfm carb.

 

[alldodge]

So get a 650 cfm carb.

Only if you plan on balancing the engine so you can turn it at 5300 rpm. This along with having an intake, and heads which can flow that much. The cfm calculator only tells us what the engine can do with an unrestricted air flow. Every intake, carb and head has variables which can be modified to achieve the flow, that said this max cfm can only be done running at WOT and max rpm.

My thought would be in the 600 range unless your going to do the full Monty (so to speak)

 

[Bigdave196]

My thought would be in the 600 range unless your going to do the full Monty (so to speak)

Is there a good carb that you would rec? I remember Carter AFB's were a 625 cfm unit. I don't want to over carb, but there are those times when i have to let it all hang out and see where I am at with other boats .

I plan on going up to either a 21* or 23* prop with the rebuild depending on how the boat handles the new motor. Should I just re-prop and control my rpm's that way and keep it at 5100 max?

 

[Tail_Gunner]

http://forum.grumpysperformance.com/viewtopic.php?f=55&t=109
http://forum.grumpysperformance.com/viewtopic.php?f=55&t=58

Have a read...maybe more than you wanted to know but it will give you a good foundation.

 

[Bigdave196]

http://forum.grumpysperformance.com/viewtopic.php?f=55&t=109
http://forum.grumpysperformance.com/viewtopic.php?f=55&t=58

Have a read...maybe more than you wanted to know but it will give you a good foundation.

Thank you.

 

[alldodge]

Is there a good carb that you would rec? I remember Carter AFB's were a 625 cfm unit. I don't want to over carb, but there are those times when i have to let it all hang out and see where I am at with other boats .

I plan on going up to either a 21* or 23* prop with the rebuild depending on how the boat handles the new motor. Should I just re-prop and control my rpm's that way and keep it at 5100 max?

My comment came from the posting of turning 5300 rpm. You don't want to build an engine that would turn 5300 and prop it so it only turns 5100, you would have wasted money and put more strain on your motor. So if you build a 383 and keep it in the 5000 to 5100 range, you don't need the higher cfm carb. My guess would be a good 600 cfm carb would work. Others here are better at determining which carb is better for your over all build then I, so I'll let them advise