6.2L performance mods...again.
 

Just curious to see if anyone has had any luck with simple mods to stock 6.2 MPI engines. The most recent posts I have read are over a year old and express various opinions of cost vs. gain. The K&N issue seems to concern application...have they (K&N) come up with any arrestors that are made for the 6.2? Any other advice/info will be appreciated!

G-

We've added Stainless Marine exhaust to a stock engine and picked up 1, maybe 2 MPH and a good midrange improvement. The MPI is the same as a 350 Mag, so a 350 Mag flame arrestor will work. You could swap in a set of 1.6 rocker arms for another 5-10 HP. You can't do anything with the ECU programming if you have the Motorola ECU. You could add an adjustable fuel pressure regulator to richen it up just a tad after the mods. Beyond that you will have to go internal to the engine.

Thanks for the reply. I will visit your website to check pricing and availability. How would I know what ECU is installed on the engines? Also, will the addition of any of these mods effect the warranty?

G-

Gferdon, I had some 6.2's that I did a few things to. I Installed the 1.6 ratio rockers, Large oil pan, Change the ECU to a Mefi3 that we could re-map, Aluim. Heads, ARP Stud Kit on Mains, & Whipple Superchargers.

I assume that you are not looking to Add a Whipple but that is by far the best way to make HP with that motor.

The Higher ratio Rockers did work well but I had a problem braking Rocker Studs. I went to the Longer ARP's and I "think" that would have fixed it. (I forgot to tighten one of the Polly Locks and a rocker came loss resulting in a piston thru the side of my block, I was running at 15lbs of boost so I didn't have much room for error but thats another story) Anyway I still have two sets of Comp Red's in the 1.6 ratio if you are interested. Just make sure to have someone that knows what they are doing install them.

If you can get a MEFI3 then I would suggest changing heads and cam. That motor can take a ton of abuse.

Pyle

The Motorola ECU is a silver unit whereas the MEFI 3 is solid black. The exhaust shouldn't void the warranty. Changing rocker arms or fuel pressure most certainly would. I don't have a lot of info posted on my web site. It's still in progress. Give me a call if you'd like to talk.
830 6935591

Bob Lloyd

Cat & Mice, what aluminum heads did you use? Dustin was trying to talk me into the Edelbrock E-tec heads with his supercharger. What kind of HP are you getting? Naturally aspirated I believe the Vortec heads with porting and larger valves are as good as anything out there up to .525 lift. Aluminum is definitley the way to go with a supercharger.

Since the boat is only two weeks old, I am a bit reluctant to do anything that will void the warranty so the rockers are out for now...thanks anyway C&M. The exhaust and K&N sound like a very reasonable investment. I was unable to reach the TFM website only saw the testimonials from satisfied customers. I will give you a call to discuss the exhaust system. I went to the K&N website and found what they list as a small block, late model MPI with serpentine belt system flame arrestor kit. It consists of two units, an adapter and the arrestor itself...does that sound right?? I will check the ECU later today and see what I have. With the addition of the exhaust and intake, would you still increase the fuel pressure/volume?

Good weekend to all.

bobl, I don't think Dustin had a intake for the Vortec when I did mine, We used the Dart's.

I would agree that if you can use the Vortec style that would be great.

We Got just under 600hp out of my old setup. The new 406ci are making over 800hp. I still have both of the blocks from the old motors, one is still in great shape with pan to intake.

Pyle

I have a pair of 6.2s and I used the kn IA59-5001 air filters. I had to remove the stud extensions on the throttle body which is very easy to do. Dwight

Thpanks for the part number Dwight, I will give it a try. What type of boat do you have?

I have a 33 Challenger offshore. It has a DDC hull and a 9ft beam. I am impressed with these engines. What do you have? Dwight

I have a Fountain 29 Fever that I really wanted a single 525 EFI but I was made an offer I could not refuse! I must admit that I love the twins and hope to get just a bit more performance without too much investment...right!! Gary

Cat and Mice how much do you want for the rocker arms? and would it be any problem installing on the 6.2 vortech heads? What power do you have now? Thanks Dwight

You need self aligning rocker arms for the Vortec heads.

Will the rocker studs be ok with 1.6 rockers? Do you recommend a certain brand of rocker? thanks

Most mfgs. make rockers specifically for the Vortec heads. The stock studs are fine in my experience. Where you run into a problem is the retainer hitting the valve guide at maximum lift. The stock 6.2 cam has .465 lift. On the heads I've checked this is about the maximum lift before an interference problem. So, the 1.6 rockers may not work without machining the guides. The 6.2 cam has the same specs as the crane 2032 cam just for the record,.452/.465 lift, 214/220 @ .050 duration.

Thanks for the help. Do you have a brand of rocker you like over another?

TTT,,, I'll be back when I have more Time

Whitey,, On the K&N site, I found the Part #59-001 but not a IA59-5001. Is it the Same?

I have the 6.2's in a 32 Sunsation and LOVE them! I added IMCO exhaust but everything else is Stock!! I am "VERY" interested in any ADD-ON'S that any of you have tried and liked!!

mama tryed:

What type of improvment did you see with the Imco exhaust? Also, how much was each system and did you do the work yourself? Like to know what your setup is like, i.e. props, drives, drive ratio, etc. when you have time.

G-

Hey G, The Dealer that I bought the Boat from, installed the Imco Exhaust for me when I bought the Boat , so I can't give you a before and after scenario! I cant remember what they cost, I bought it in Jan.2002. I'll dig through my Files and try to find a reciept.

I'm turning Labbed 3blades , 23 pitch, WOT 5100 rpm,, Speedo 72, gps 69.3,MPH,,, Bravo 1,, 1.5,,

I know I have a few more RPM to play with, I'm hoping the K&N might help that a little.

How tight {rpm's} are you running yours at WOT?

Oh Yea,,, I've got everthing in mine I could get,,Air,TV,Microwave, Vac-u-flush Head, Fridge,etc,,,

I do not know if the chargers are the same or not. I got the #s off of the Box the cleaners came in. I did not notice a difference with the cleaners but, They look cool.

Most 6.2s have the 1.65 outdrive on them. I wonder if they changed the ratio in the later ones. I also like these engines and I turn mine about 5k. I run 2 different props I have a pair of 23s and a pair of 25s. My top speed is from 62-65 on gps. It depends on how the payload is. My boat is a big 33 so the speed is not to bad considering the size of my boat. Dwight

mama/dwight...

I have a new 29 Fountain Fever with the twin 6.2's. As you are probably aware, the Fever is fairly light and has little in the way of amenities, no stove, air, etc. In stock trim it runs 71 on the gps with the 20 hours I managed to use it after delivery in the fall. I have the 1.65 ratio standard Bravo drives and with stock 26" Bravo1 props and was hitting the rev limiter at 5350rpm (trimmed out, nearly full fuel, 2 souls on board).

I had the props labbed by Houston Propeller and they also pitched them up to 27"...I hope to gain 1-2 mph and bring down the rpm. Things are starting to warm up around here and I will give you an update when I splash the boat in (I hope!) a couple of weeks.

Whitey, alot of people agree with you that there is no increase in performance when changing to the Filterchargers...but they definitely do look cool! Do you know if there are any problems with Coast Guard safety checks?

G-

The filter is coast guard approved. It is on the box they came in. I also believe that I seen it on the charger itself

What Oil are you Guy's running? I have always used Mobil One , Synthetic..15- 40 I think it is,, but I bought a Case of Royal Purple this Week , straight 30 , that I'm going to use,, I freaked when he told me the Price of the Case:D :D :D and Ithought Mobile One was high!!!
I have always used the Wix Hi-perf Filter #51069
You guys have me curios on my Drive Ratio now, I'm going to lok a little bit closer today, when i'm changing my oil!!
5350 rpm is where you "bumped" ,,intresting ,, I may have to tell Julie I need a little more,, next time I have any prop work done......

I am a M1 fan but, I have found that I get the best oil pressure with a 40 wt. So I use castro 40 when possible. In case you have not noticed the oil pressure on the 6.2 is what I would consider on the low side but, I have heard it is to do with the oil pump and it is a drag reducing trick used by GM. It does not cause a problem but, it kinda makes you worry the first time out.
I have been using the wix filter also. Another thing you may want to consider is to add a oil cooler. I am not sure why but Merc did not add one to this engine. Dwight

Dwight.. so how you doin with yo motors? :D

Well they are coming along. I have a delima right now. I took my boat back to the plant to get some repairs done and someone saw it and are very interested in buying it. So I am on a holding patern until I hear back as to wether they want to buy or not. If I sell I am going back to a single. Dwight

cool.... :D I'll sell you a single 18' :D :D Adult driven :D and never abused :eek:

No you keep that boat, those are one of my favorites little boats. Yours is in awesome shape on top of it all.
What else would you buy?

I still owe in it till sep 2006.. Only paid $8750 and have put over $15,000 in motors in it :eek: Kinda getting tired of it..



and what else would I buy...... a dirtbike :D :D

Oh quit it....You need boat, boat need Travis.

if it was paid for it would be a different story. but all those motor parts are still on my credit card which is running WFO at $7500 last time I looked :( Up north at our lake house, I am just having trouble cruising around the lake. If i run this year, its just gonna be a handful of dealings with the damn sherriffs.. :mad:

Maybe you should come over to Hardy a few more times. You have to remember that the reason you have so much in the engines is because you wanted to push them. Now you could build a very stable 400-450 horse engine and run forever but, you do not want to do that do you?.... :D

being that I need the money and I know this hull won't go much faster. it weights in at 2950 lbs and with the very low X dimension I would have to find a alpha ss, and that would cost lots of mula. I am hitting a brick wall and thinkin about callin it quits. Sooner or later the drive will break and when it happens I won't have the money to fix it. hell with the last motor it was around 500 hp or a little more, and the damn boat would only do about 74-75 mph. If you know the speed formula run this for me... 1.5 gear, 5500 rpm, 24" pitch.

That comes to 83 mph. I figure you are at about 11% slip. You are gitting a bit to much slip. The highest preferred is about 12 according to BAMs website. What prop are you running?

When I calculate your weight and hp with the high slip #s I come up with around 90mph. I think you could use alot more prop.

running a labbed 24" mirage. it would only spin around 5000 with this prop non-labbed I have to trim so high to get the rpms and to get the boat out of the water I figured my slip#'s would be higher. i never had a gps on this motor.. the previous motor I had 70.1 on gps. So i figured this one was around 74-75. I need to find a prop that gives good bow lift and some stern lift.. but right now the prop is the last thing on my mind..

thanks for the #'s dwight

Have you tried to use a 4 blade? I also wonder if how it would run with a hydromotive? Well one step at a time.