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gatorguy
09-13-2011, 04:01 PM
Ok, before the flames start a little disclaimer: I am not Hooligan, nor am I related, nor have I ever met him. That being said, I am interested in doing a little engine work on my 97 PS205 with the 275hp, EFI, 350 chev.


My reasoning for wanting to do some mods are as follows:

1. I have 4 boys and would like to teach them how to work on stuff.
2. Winter is coming and we need a project.
3. I have never done any internal engine work and would like to learn.
4. While 275hp pulls up all 195lbs of me pretty darn quick here in Oklahoma where the elevation is 1100ft, when we took the boat to Lake Powell which was about 3700 ft, it felt like it took about twice as long to get up.
5. With a few more HP I could turn a bigger prop which would help the boat hold a more consistent speed when loaded down with 1500lbs ballast plus people when we are boarding and surfing.
6. Bigger is always better right?

Why I should just leave it alone:

1. I have never done any internal engine work and would like to learn. (#2 above)
2. It works fine now and the biggest enemy of good is better.

joniron1
09-13-2011, 04:15 PM
Kind of on board with leave it alone. Maybe a different prop? That being said bigger is often better!

mig
09-13-2011, 04:47 PM
Is that a TBI engine?

KnoxX2
09-13-2011, 04:48 PM
Leave it alone and get a cheap old car or truck to work on. Then let the boys drive it in HS. They would have the experience of working on it and have time invested in it. Just a thought.

LYNRDSKYNRD
09-13-2011, 05:01 PM
Leave it alone and get a cheap old car or truck to work on. Then let the boys drive it in HS. They would have the experience of working on it and have time invested in it. Just a thought.

If you got this route get an old jeep....but I am not against working on the boat either.

gatorguy
09-13-2011, 06:25 PM
Leave it alone and get a cheap old car or truck to work on. Then let the boys drive it in HS. They would have the experience of working on it and have time invested in it. Just a thought.

Yea, we've thought about this too. We've been looking for a mid 70's F250 4x4. I would love to do a frame off Jeep build with my son, but when I started telling my wife about it and got to the part about a lift and 35" tires she got all worried about the boys driving it and outlawed any lift. A jeep without a lift is like America without apple pie. Also thought about getting a 5.0 mustang and bolting a few things on to make it fast, but I don't think any young boy, or old one for that matter, can resist all that power, and I'm not to intrested in peeling my kid off a telephone pole. I figure with a truck they can put a lot of sweat into it, and then they will take better care of it.

This still doesn't help me with desire for more power. I already talked with Erik at OJ and he said I'm running the right prop, so I'm back to either leaving it alone, or messing with it.

gatorguy
09-13-2011, 06:26 PM
Is that a TBI engine?

Yep .

tommcat
09-13-2011, 07:07 PM
dont "learn" engine repairs on your boat unless you have a spare

j.mccreight@hotmail.com
09-13-2011, 07:33 PM
I say go for it, you'll never "learn" if you don't do it. I wish my dad had done projects like this with me, I started "learning" when I was 14 on a 69 dodge charger. You can do a top end kit for around $2000 and it would be a nice performer. The only thing that might be an issue is the mefi controller b/c its a speed density system but their are parts out there that are designed to work with stock computers. And you might have to research to see if the tbi intakes are the same as in the cars, if they are then you could have a screamer not a hooligan.8p

JimN
09-13-2011, 08:20 PM
I say go for it, you'll never "learn" if you don't do it. I wish my dad had done projects like this with me, I started "learning" when I was 14 on a 69 dodge charger. You can do a top end kit for around $2000 and it would be a nice performer. The only thing might an issue is the mefi controller b/c its a speed density system but their are parts out there that are designed to work stock computers. And you might have to research to see if the tbi intakes are the same as in the cars, if they are then you could have a screamer not a hooligan.8p

If I had this boat, I would look for a Vortec marine engine, like they used starting in '98. That's rated at 310HP. If I wanted to go for a less expensive solution, I would go with roller rockers/lifters/cam and a more efficient intake manifold. However, the ECM calibration still won't be "correct" unless the replacement engine is just like the newer TBI and the ECM is recalibrated for something closer, which will be tough considering the fact that the '99 Prostar hull is different from the '98.

MIskier
09-13-2011, 08:28 PM
Ok, before the flames start a little disclaimer: I am not Hooligan, nor am I related, nor have I ever met him. That being said, I am interested in doing a little engine work on my 97 PS205 with the 275hp, EFI, 350 chev.


My reasoning for wanting to do some mods are as follows:

1. I have 4 boys and would like to teach them how to work on stuff.
2. Winter is coming and we need a project.
3. I have never done any internal engine work and would like to learn.
4. While 275hp pulls up all 195lbs of me pretty darn quick here in Oklahoma where the elevation is 1100ft, when we took the boat to Lake Powell which was about 3700 ft, it felt like it took about twice as long to get up.
5. With a few more HP I could turn a bigger prop which would help the boat hold a more consistent speed when loaded down with 1500lbs ballast plus people when we are boarding and surfing.
6. Bigger is always better right?

Why I should just leave it alone:

1. I have never done any internal engine work and would like to learn. (#2 above)
2. It works fine now and the biggest enemy of good is better.

You will not be able to run a larger diameter prop than what is on the boat, max prop diameter is a function of tip clearance with the hull among other things. You would be better off buying a prop suited for high elevations if you want a better hole shot at altitude.

tommcat
09-13-2011, 08:36 PM
jim, in what way is a 99 205 hull different than a 98? to my knowledge the hull is identical from 96 to 2000 with the only changes being above the hull in 99 i think?

JimN
09-13-2011, 08:52 PM
jim, in what way is a 99 205 hull different than a 98? to my knowledge the hull is identical from 96 to 2000 with the only changes being above the hull in 99 i think?

The '98 needed hydrorails in order to leave a better wake. The hull and deck were new and the old hull was used for the SportStar.

ahhudgins
09-13-2011, 09:32 PM
I agree with other repsonses: Find something else to tinker with. If youíve never been inside an engine you can mess up a lot of things by trying to fix something that isnít broke or by trying to ďbolt onĒ more horsepower. Iím a pretty good shade tree mechanic and Iíve tried to include my 2 sons in several of my projects but they lose interest very quickly. Apparently itís not as interesting as texting or Facebook.

My son brought home some software and cable to hook up to his street bike and heís going to make some ďadjustmentsĒ. Iím going to just sit back and watch the carnage. He tore into his 4 wheeler and it hasn't ran since. Don't want you to end up in the same situation.

MissileMech
09-13-2011, 10:02 PM
It took a lot to keep my boys interested in a simple engine R&R. Once the hard detail work starts they will probably lose interest and leave you to finish. They will be more motivated to work on something they drive regularly and have to rely on for daily transport. But only you know your boys and how engaged they would be.

1redTA
09-13-2011, 10:14 PM
edelbrock TBI manifold, 1.6 roller rockers and some of those sexy marine headers

Jorski
09-13-2011, 10:27 PM
You will not be able to run a larger diameter prop than what is on the boat, max prop diameter is a function of tip clearance with the hull among other things.

By "larger", I think that he means higher pitch, not diameter. With more power he could run a higher pitched prop.

tommcat
09-13-2011, 10:33 PM
The '98 needed hydrorails in order to leave a better wake. The hull and deck were new and the old hull was used for the SportStar.

interesting. so that means everything i've ever read is wrong:mad:
do you have any links to that info? i'd like to check it out, never even heard of hydrorails

gatorguy
09-13-2011, 10:35 PM
I've pulled the head on an old DOHC escort, and changed water pumps and alternators etc on cars and trucks. I've worked a ton on small 2 and 4 stroke engines like bikes snowmobiles and yard equipment. Things that I had to fix if I wanted to keep using it. I'm not afraid of tearing into something bigger, and I think I have enough guys on speed dial that can get me out of a bind.

1redTA has about the right idea. I just don't know what will work together, vs. what is just a waste of money, vs. what is going to screw me up. I'm not very intrested in sitting with a laptop trying to remap the computer or whatever it is you see guys trying to do. I am more intrested in a "works first time" off the shelf, grab and go type of project. Maybe there isn't one, and if not I'll look for something else to work on. But I have got a boat already, some spare time, some money I can put towards the project and some willing helping hands.

dmminfla
09-14-2011, 07:43 AM
The '98 needed hydrorails in order to leave a better wake. The hull and deck were new and the old hull was used for the SportStar.

The boat in question is the 97 PS205 I think JimN is refering to the 190

CantRepeat
09-14-2011, 07:57 AM
I've pulled the head on an old DOHC escort, and changed water pumps and alternators etc on cars and trucks. I've worked a ton on small 2 and 4 stroke engines like bikes snowmobiles and yard equipment. Things that I had to fix if I wanted to keep using it. I'm not afraid of tearing into something bigger, and I think I have enough guys on speed dial that can get me out of a bind.

1redTA has about the right idea. I just don't know what will work together, vs. what is just a waste of money, vs. what is going to screw me up. I'm not very intrested in sitting with a laptop trying to remap the computer or whatever it is you see guys trying to do. I am more intrested in a "works first time" off the shelf, grab and go type of project. Maybe there isn't one, and if not I'll look for something else to work on. But I have got a boat already, some spare time, some money I can put towards the project and some willing helping hands.

Well, that's a problem with computer controlled EFI systems. If you change stuff and do not tune the computer you're not going to get everything you could from those parts.

Tuning the spark curve(both cold and warm), VE tables, BLM min and max values, fuel mapping/pressure so you stay at 14.7 AFR is going to be a must.

wtrskr
09-14-2011, 10:41 AM
Didn't Mastercraft keep the chevy 350 tbi but get more than 275 HP in later years with a different intake manifold (Vortec) and possibly other changes? Is it possible to make those same changes then have a Mastercraft dealer upgrade his ECM settings to the same as those later years? I know little about these things, just throwing a thought.

mig
09-14-2011, 10:56 AM
Last winter I modifed the 310HP 5.7 in our boat with aluminum vortec heads, aluminum exhaust, cam change. I was able to add a little fuel with out changing jets by turning up the pressure bypass in the TBI and got normal idle after resetting idle on the TBI. TBI seems able to make some compensation for parts changes w/o a lot of work. I did not have to mess with the engine management and have enjoyed the power increase. Going aluminum shed some lbs. so I have convinced myself the wake is improved too :) I don't know the difference between the 310HP and yours - you may need to get a BB TBI, but I doubt the timing curve/injector control is much different. You could check the part numbers on the ecm for each engine to see if they are the same.

tommcat
09-14-2011, 11:07 AM
The boat in question is the 97 PS205 I think JimN is refering to the 190

ah, that makes more sense.

CantRepeat
09-14-2011, 11:09 AM
Last winter I modifed the 310HP 5.7 in our boat with aluminum vortec heads, aluminum exhaust, cam change. I was able to add a little fuel with out changing jets by turning up the pressure bypass in the TBI and got normal idle after resetting idle on the TBI. TBI seems able to make some compensation for parts changes w/o a lot of work. I did not have to mess with the engine management and have enjoyed the power increase. Going aluminum shed some lbs. so I have convinced myself the wake is improved too :) I don't know the difference between the 310HP and yours - you may need to get a BB TBI, but I doubt the timing curve/injector control is much different. You could check the part numbers on the ecm for each engine to see if they are the same.

You might be making more power, but I'm sure tuning would make your setup a lot better. The only issue with marine datalogging is there are so few programs out there and the hardware seems to be a lot more then what is needed for a car.

TBH: I'm very supprised you were able to overcome the idle issue of a new cam, not sure how much the profile changed, with just adding more fuel pressure.

As far as spark curve goes I'd bet they are not the same from engine to engine. Hotter(an 80s trem) cams are going to need more spark sooner to get maximum results.

gr82bgreen
09-14-2011, 11:23 AM
You might be making more power, but I'm sure tuning would make your setup a lot better. The only issue with marine datalogging is there are so few programs out there and the hardware seems to be a lot more then what is needed for a car.

TBH: I'm very supprised you were able to overcome the idle issue of a new cam, not sure how much the profile changed, with just adding more fuel pressure.

As far as spark curve goes I'd bet they are not the same from engine to engine. Hotter(an 80s trem) cams are going to need more spark sooner to get maximum results.

What if you left the cam alone and installed vortec heads and intake.

j.mccreight@hotmail.com
09-14-2011, 12:04 PM
Ive done his swap on tbi trucks, a simple head and intake swap will not need to tune ecm, these tbi ecm are able to adjust a small amout, if your a little lean you can install an adjustable map sensor to trick the ecm into adding more fuel. When you start changing cams and t-bodys thats when the ecm needs to been tuned. Just with a good set of edelbrock or trick flow heads nothing to wild just idle-5500 rpm with matching intake your looking at about a 50 hp increase. My last swap was for my parts guy and is his daily driver for 5 years now. Those who say it can't been done can raz me if they want but ive done it and its works without ecm calibrations. Albiet a truck not a boat.

tommcat
09-14-2011, 12:34 PM
Ive done his swap on tbi trucks, a simple head and intake swap will not need to tune ecm, these tbi ecm are able to adjust a small amout, if your a little lean you can install an adjustable map sensor to trick the ecm into adding more fuel. When you start changing cams and t-bodys thats when the ecm needs to been tuned. Just with a good set of edelbrock or trick flow heads nothing to wild just idle-5500 rpm with matching intake your looking at about a 50 hp increase. My last swap was for my parts guy and is his daily driver for 5 years now. Those who say it can't been done can raz me if they want but ive done it and its works without ecm calibrations. Albiet a truck not a boat.

you need to remember that in a car or truck it is closed loop and the ECU has the ability to a certain extent to see what changes were made and can compensate to a degree. boats have no O2 or MAF sensors and do not see any of the changes you made. so if it was programmed to have a certain fuel pulse width at a given load/rpm and you make some changes, it will still have the original fuel and spark curves at that given range. even if it is way wrong for the head, cam or intake.

JimN
09-14-2011, 01:21 PM
Didn't Mastercraft keep the chevy 350 tbi but get more than 275 HP in later years with a different intake manifold (Vortec) and possibly other changes? Is it possible to make those same changes then have a Mastercraft dealer upgrade his ECM settings to the same as those later years? I know little about these things, just throwing a thought.

They stopped using Ford when Ford got out of the marine business. The Vortrec engines have different heads, intake, rockers/lifters and calibration. The problem with just going to a dealer for the recal is that MC calibrates the ECM based on the overall boat, not just a known weight. If they were to use one program and had hulls of different efficiencies, the boats with an inefficient hull would have no chance to perform as well as the more efficient hulls. The program is identified by its checksum but there's no easy way to know what differences are involved in the programs. I'm not saying it's impossible, though. It would be possible to use a program for a similar model and have decent performance but it couldn't be guaranteed unless the existing boat is made to be exactly like the one that the program is intended for.

CantRepeat
09-14-2011, 05:11 PM
Ive done his swap on tbi trucks, a simple head and intake swap will not need to tune ecm, these tbi ecm are able to adjust a small amout, if your a little lean you can install an adjustable map sensor to trick the ecm into adding more fuel. When you start changing cams and t-bodys thats when the ecm needs to been tuned. Just with a good set of edelbrock or trick flow heads nothing to wild just idle-5500 rpm with matching intake your looking at about a 50 hp increase. My last swap was for my parts guy and is his daily driver for 5 years now. Those who say it can't been done can raz me if they want but ive done it and its works without ecm calibrations. Albiet a truck not a boat.

I think vehicle ECMs need more tuning then boats would. There's probably 2000 lines of hex in a single .bin file and hundereds of scalars, flags, and tables used. Sure you could get away with not tuning but you are not getting all the performance, mileage, and could even be doing harm to components.

The software and hardware used to tune GMs as well as a lot of other ECM/EFI packages are pretty easy to get and don't cost that much. The definition and bin files are pretty easy to get. The trouble is learning what the tables are and how they affect other parts of the tune.

gatorguy
09-14-2011, 05:20 PM
They stopped using Ford when Ford got out of the marine business. The Vortrec engines have different heads, intake, rockers/lifters and calibration. The problem with just going to a dealer for the recal is that MC calibrates the ECM based on the overall boat, not just a known weight. If they were to use one program and had hulls of different efficiencies, the boats with an inefficient hull would have no chance to perform as well as the more efficient hulls. The program is identified by its checksum but there's no easy way to know what differences are involved in the programs. I'm not saying it's impossible, though. It would be possible to use a program for a similar model and have decent performance but it couldn't be guaranteed unless the existing boat is made to be exactly like the one that the program is intended for.

So how do I make changes? Is that what the guys are doing with the lap top? A bunch of trial and error until you get a good power curve? I said I'm not interested in doing that, but I guess what I really should have said is that I don't have a clue when it comes to that stuff and I'm a little intimidated by it, and don't what to blow up my motor.

CantRepeat
09-14-2011, 05:22 PM
What if you left the cam alone and installed vortec heads and intake.

Well, I would say you are not getting all you could from the heads and intake. The main thing about engine design or upgrades is parts that are designed to work together are more efficient.

Engineers are making far more horsepower and torque these days because of better design.

IE a 400 sbc back in the day made 275hp while a 376ci sbc today makes near 600hp.

On a side note: The LS6 is 10.5 motor and requires premium unleaded so when the new MV8 only needs 87 I'm pretty impressed with the tuning. I bet that knock attack and recovery table is a trade secret. ;)

tommcat
09-14-2011, 06:57 PM
So how do I make changes? Is that what the guys are doing with the lap top? A bunch of trial and error until you get a good power curve? I said I'm not interested in doing that, but I guess what I really should have said is that I don't have a clue when it comes to that stuff and I'm a little intimidated by it, and don't what to blow up my motor.

yes that is what guys are doing when you see them tuning with a laptop. with a car you either go to the dyno or the track and make small adjustments and see what the results are. did it gain or lose power, did the A/F ratio go rich or lean, did the engine detect any detonation and so on. i would think even with a laptop it would be pretty hard to make those small adjustments in a boat. you may be able to detect gains in acceleration or driveability but A/F would be much tougher. not impossible, just much harder than with a car or truck.

1redTA
09-14-2011, 09:12 PM
most GM engines run a little extra fuel in the curve, adding some more air to the engne will help lean you out a little, making more power safely, in my opinion. When I first added some go fast parts to my LT1 in my TA, I had it tuned by PCM4Less with a bolt-on tune, when I added the LT4 HotCam and 1.6 rockers I left it the same, Alvin (programmer for PCM4Less) told me it would run just fine with out another tune. Unless you add cubic inches, heads or a cam you can get by with quite a lot on the stock tune

gatorguy
09-15-2011, 10:54 AM
So where would I be able to look for help with tuning it if I go ahead and add some stuff. I'm thinking headers, intake, a cam, and a new prop. Also Kyle suggested a TBI spacer. Would that still be useful/needed if I change out the intake?

Also where is a good place to start doing research on what I want to buy so that it all works together?

j.mccreight@hotmail.com
09-15-2011, 11:45 AM
Imo if your going to change out your stuff buy a complete top end kit from one manufacturer that you you know all the parts were designed to work together. Summitracing or jegs is a good place to look at parts and do your start research.

tommcat
09-15-2011, 11:58 AM
It's your boat, time and money so obviously you should do what you want with it, but just let me add one more thing. i work on vehicles for a living, can rebuild an engine in my sleep, have built plenty of performance engines and specialize in electronic engine controls and yet i still opted not to do anything with my engine simply due to the time and cost involved in getting it tuned correctly in a boat. impossible? no but costly and time consuming and i dont want to spend my summer trying to tune the engine in my boat that previously ran great.

JimN
09-15-2011, 12:21 PM
So where would I be able to look for help with tuning it if I go ahead and add some stuff. I'm thinking headers, intake, a cam, and a new prop. Also Kyle suggested a TBI spacer. Would that still be useful/needed if I change out the intake?

Also where is a good place to start doing research on what I want to buy so that it all works together?

With a good intake, cam, maybe rocker arms, a spacer won't add much. If you have the Vortec engine, you won't find an intake that will add much of anything, either and that already has roller rockers/lifters. That's a very good intake manifold and it's not a GM part- it was designed by someone else who's no longer with us, unfortunately.

If they disassemble the engine (unlikely, since Jasper wants the core to be intact), the cam may have a part number that can be researched to get the lift/duration/valve timing specs.

gatorguy
09-15-2011, 12:22 PM
It's your boat, time and money so obviously you should do what you want with it, but just let me add one more thing. i work on vehicles for a living, can rebuild an engine in my sleep, have built plenty of performance engines and specialize in electronic engine controls and yet i still opted not to do anything with my engine simply due to the time and cost involved in getting it tuned correctly in a boat. impossible? no but costly and time consuming and i dont want to spend my summer trying to tune the engine in my boat that previously ran great.

I know exactly what you are saying. My next boat project is actually redo the vinyl, carpet, and buff the gelcoat. I'm just thinking out loud about future projects, and about something to do with my kids. Likely I will get an old truck to do any real engine work on with the kids. But if I opt to keep this old beauty vs buy a new X7/X14 I would like a little more power, and want to know how hard it is going to be to get it.

JimN
09-15-2011, 12:25 PM
So how do I make changes? Is that what the guys are doing with the lap top? A bunch of trial and error until you get a good power curve? I said I'm not interested in doing that, but I guess what I really should have said is that I don't have a clue when it comes to that stuff and I'm a little intimidated by it, and don't what to blow up my motor.

Tuning is trial and error but to do it right, all kinds of other info is needed. Exhaust gas temperatures are important and although the engine may seem to run fine, it may be too lean and a catastrophic failure would be on the horizon. The initial tuning is usually done on a dynamometer and then in the vehicle, so the fine tuning can be performed.

gatorguy
09-15-2011, 12:30 PM
Thanks for all the input guys. I'll do some more research and reading, and probably leave it alone in the end, but there is always dreaming.

JimN
09-15-2011, 03:08 PM
Thanks for all the input guys. I'll do some more research and reading, and probably leave it alone in the end, but there is always dreaming.

Do you have a speed shop nearby? They may have some ideas, too. Bottom line- an engine is an air pump and if you make it breathe better, it will perform better (assuming the air/fuel ratio is correct).

gatorguy
09-15-2011, 03:20 PM
Do you have a speed shop nearby? They may have some ideas, too. Bottom line- an engine is an air pump and if you make it breathe better, it will perform better (assuming the air/fuel ratio is correct).

Not that I know of, but I do have a friend that builds motors for dragsters that are in the low 5-6sec (don't quote me on the time, but he and his son compete with the pros, or so he claims. He has a huge garage and all kinds of fancy equipment. I figure I can pick his brain for help with what to bolt on, and I bet he could even help with the tune. His name is Fred Brewer and I guess he even makes some heads that are available commercially.

Well if nothing else, this discussion has helped me to identify my available recourses. I donít know why I didnít just talk to Fred in the first place.

CantRepeat
09-15-2011, 03:31 PM
Arizona Speed and Marine does tuning on boats.

http://www.azspeed-marine.com/index.html

But here is a case in point.

This software for tuning MEFI4 ECUs (http://www.azspeed-marine.com/inmaso.html) cost $1500 while the same type of software for OBD1 and OBD2 ECUs can be purchase for as little as $39 or even free depending on what package you want.

1redTA
09-15-2011, 04:10 PM
Try using TunerPro, it's free and works for the automotive LT1. I used it on my car the trick for tuning is to back up the current tune and to alter one thing at a time

CantRepeat
09-15-2011, 04:24 PM
Try using TunerPro, it's free and works for the automotive LT1. I used it on my car the trick for tuning is to back up the current tune and to alter one thing at a time

The trick to tuning is know what your changing and more importantly why you are changing it.

TurnerPro doesn't have an interface for Marine MEFI and I do not think your are going to find a DEF file. With out a DEF file you wont be able to edit tables. Moreover, the hardware need to interface with the Marine OBD is costly as well. Motes' autoprom will not work with Marine MEFI so again using TurnerPro isn't an option.

There are other Marine MEFI tools, hardware and software but they are very costly.

gatorguy
09-15-2011, 05:28 PM
Not that I know of, but I do have a friend that builds motors for dragsters that are in the low 5-6sec (don't quote me on the time, but he and his son compete with the pros, or so he claims. He has a huge garage and all kinds of fancy equipment. I figure I can pick his brain for help with what to bolt on, and I bet he could even help with the tune. His name is Fred Brewer and I guess he even makes some heads that are available commercially.

Well if nothing else, this discussion has helped me to identify my available recourses. I donít know why I didnít just talk to Fred in the first place.

I just got back from talking with my friend and he said their car will do about 3.7 sec in the 1/8 mile. He also said that he would think about how to tune my boat. He's pretty sure he can help me.

mig
09-17-2011, 11:35 AM
gatorgy, I had 70+ hours on my 383 tbi combo before wrecking my leg in July and it has been great, I think copying the Predator 310HP recipe would be easy and effective for your engine. I think you can easily turn your engine into the 310hp configuration without resorting to tuning the ecm. The O.E. style cam is available cheap on ebay, BB throttle bodies and the same injectors O.E. to the 310HP are plentiful and not that expensive. BB TBI intakes are not expensive, your exhaust is probably the same already as the Predator engines. If the ECM is different, you should be able to purchase one from an MC dealer. Just my opinion, but I am sure you could make a noticeable, reliable power difference for $600 (and maybe the cost of the 310HP ECM) and your time.

gatorguy
09-17-2011, 09:14 PM
gatorgy, I had 70+ hours on my 383 tbi combo before wrecking my leg in July and it has been great, I think copying the Predator 310HP recipe would be easy and effective for your engine. I think you can easily turn your engine into the 310hp configuration without resorting to tuning the ecm. The O.E. style cam is available cheap on ebay, BB throttle bodies and the same injectors O.E. to the 310HP are plentiful and not that expensive. BB TBI intakes are not expensive, your exhaust is probably the same already as the Predator engines. If the ECM is different, you should be able to purchase one from an MC dealer. Just my opinion, but I am sure you could make a noticeable, reliable power difference for $600 (and maybe the cost of the 310HP ECM) and your time.

JimN and CantRepeat, and anyone else smarter than me, what do you think of mig's idea. It sounds good to me if it would really work.

j.mccreight@hotmail.com
09-17-2011, 09:57 PM
Assuming that would work, a new t-body is gonna cost at least $450, another $200 for camshaft, a new tbi intake $265, you can figure a couple hundred more for gaskets and misc. stuff, and the ecm will be at least $980, with the ecm, you would need to get a known good delhi number for a predator ecm, when the ecm is ordered they might need the serial numbers to match the calibrations, would the ecm even plug in directly or would you have to rewire it? Are the cylinder heads the same on your engine and the predator?, IIRC the predator had high flow cyl heads. Vortec vs non-vortec , I think this blows this $600 out the window. Don't get me wrong I'm all for more power but this is not the way. my :twocents:

one resource for ecm's http://www.bakesonline.com/searchresult.aspx?CategoryID=883

JimN
09-17-2011, 10:57 PM
JimN and CantRepeat, and anyone else smarter than me, what do you think of mig's idea. It sounds good to me if it would really work.

The throttle body on the Vortec and non-Vortec engines are the same. The power increase is due to lower frictional losses due to the roller lifters, rockers and heads and possibly the intake manifold. The ECM would need to be re-programmed, not replaced.

1redTA
09-18-2011, 06:36 AM
the marine vortec intake manifold is an upgrade over the automotive one, there is not all the poppet injectors and fuel lines inside the manifold limiting flow. Another positive for the marine intake is that you can change the injectors. Putting a marine intake on an automotive L31 usually is a $800 performance mod.

As far as the throttle body you can knife edge the blade and shave the shaft it rides on.