500 EFI Power Increase
 

I have figured out what I am doing to get the boat to run faster. I have a 35 flame, (Gary's ex boat) and want to get a little more speed increase. I would like to get it to 95 on the GPS. I currently get 88 on any day and saw 91 on a fall day.

I set some criteria for the modification to adhere to.

1. I want to use the EFI system as is.
2. I want to be able to get back to stock without a lot of work if the mod's do not work.
3. I am looking to make a 75-100HP increase.
4. I want the engines to look totally stock.
5. I do not want to loose any reliability of the engines.
6. I do not want to spend a ton of $ to get there.

I thought of all the ways of getting a 75HP increase and figured I needed to.
1. Get a little larger cam
2. Get more compression
3. Get better head flow.

Remember, the engines have almost 350 hours so they needed lifters, springs, head gaskets, and inspection at least. All 502 short block I have taken apart usually do not need to come apart. I decided to keep into the criteria, the short block needed to be left alone.

I got new cams from crane that are used in the 525 EFI. I do not think they will help the HP increase to much, but they will sound better.
I am going to install Dart Iron Eagle heads that will be milled enough to get the stock 8.75 compression to 9.5. I plan on porting and flowing these heads next week. Then I will port match the EFI unit to the heads and see what happens.

I think the EFI ECU will come to me with this mod and not need any calibration. My thinking is, they are set up rich, adding compression will cause it to lean out. I checked the engines before removing and the ECU's did not have any error codes. After I run it I will check again to see if I see any error codes appear. If so they will go to Mark at Precision Marine to do the work.

We will see soon what happens

Re: 500 EFI Power Increase
 

Sorry to cancel Thursday, but I'm soooooooo glad that boat is inside right now!!! I was at the unit from 4:40 til 5:00 then had to leave for 20 minutes. Ended up with just enough people to move it over.
What motors are you starting with???? ( :confused: read the header) Sounds like the same thing I'd like to do with mine (502's with 380 hrs.) I'll be looking for an update!!!
Russ C.

Re: 500 EFI Power Increase
 

Put a Procharger On it, it will run over 100

Re: 500 EFI Power Increase
 

My last maintenace nightmare was a blower motor. Not again if I do not have to. I stopped at every gas station and was constantly needing to work on it for some reason or another. 95 is fine for me. I have had two other people blow up there blower motors chasing me so far with 500 EFI's. See my buddies post in the Hustler section. He won the battle but lost the war.

Re: 500 EFI Power Increase
 

You go Linnie, sounds like you have the engines apart....how did they look?

Re: 500 EFI Power Increase
 

I have 100 of care free hours on this setup. I had a Checkmate with a 502 satge II and had no problems with the one either must be the people that put them together :D

Re: 500 EFI Power Increase
 

Gary,

Not got them out yet. Doing that hopefully this weekend. Have started on the new heads. First set should be ready first of next week. I'll be on the road today, I try to give you a call.

Dwayne,

I 'm glad you have has success with a blower. I probably did not say exactly what I mean. I always used the root style blowers. Everyone in my area uses either B&M or Blower Shop blowers. Most people set them up how they are suppose to and run fine, but consume a lot of gas. After they get tempted, a little more boost is just a pulley away. Then things get on the ragged edge, and maintenance issues begin.

I looked at the Procharger & the Whipple a lot. I did not like the way the Procharger looked on a Motor. I think it is probably the safest style blower to install on a engine. I have gotten to where there are so many boats in my area that run well over 100 and the people just constantly dump money into drives from large blower power. I have gone through a couple of broke drives but have had good luck with the motors staying together. Not any problem with my engine assembly. Drives generally break when they are being pushed the least. Lighter boats can get away with larger power. I wish you more continued success with your blower setup.

Linnie

Re: 500 EFI Power Increase
 

Linnie, your right I should'nt say care free I broke a drive on the Checkmate, and both drives last year on the Nordic. I replaced the drives on the Nordic with IMCO's so everything should be ok. (I would like to think)

Re: 500 EFI Power Increase
 

Dwayne

Good luck. I talked to Gary tonight & he tells me you have a 35. I upgraded both drives to XR's last year. I am having them checked now. The first passed with flying colors. Hope to keep this way. Being 30 miles out in the bay, sucks to be broken down.

Please eamil some pictures of your boat.

Linnie

Re: 500 EFI Power Increase
 

Here's some pictures of the exhaust port evolving. The chamber will needs some work to un-shroud the valves. I got the flow numbers from the first flow that were very impressive. Dart tells me to leave the intake port alone. It probably will just get some sanding. The center picture is at an slight angle.

Re: 500 EFI Power Increase
 

Picture of ported chamber. Man, winter is boring!!!

Picture before starting.

Re: 500 EFI Power Increase
 

Linne,


Are your engines apart yet?

Re: 500 EFI Power Increase
 

Gary,

Got them both out of the boat Saturday morning. Have the valve covers off the first one now. All looks well. No broken springs, but they did have the 929 springs. Will post a picture later today. I could not mess with it yesterday.

Re: 500 EFI Power Increase
 

Linnie, here are a few pictures

Re: 500 EFI Power Increase
 

Dwayne,

Is that your boat? Are the Pro Chargers a new upgrade? If not what speed did you get? I hear with that setup, the boat should run well over 100.

These EFI motors are a mess with the rigging of the accessories. About got one stripped. Took some time to figure out the best way to get them undressed.

Re: 500 EFI Power Increase
 

Linnie, I bought the boat new in 2002 from Unlimited Marine, I put 20 hours on it and then I put the prochargers on. I was going to do the IMCO drives at the same time but I didn’t. I have two young boys and don’t get to run it as much as I would like so I thought I could get by. The XZ drives lasted about 15 hours. Like I said I don’t get much time to play and work with it. I have 36 Bravo I and still hit the rev limiters and yes I have seen over 100 with four people and 100 gallons of fuel.

Re: 500 EFI Power Increase
 

That's great!!!, over 100!!! Yea!!1. I hope to get over 95 with my setup coming. I hope to get it on the water in a couple weeks.

Linnie

Re: 500 EFI Power Increase
 

Just in time, both head gaskets were getting ready to let go. #1 was in bad shape. Everthing else was in good shape. No broke springs or lifters. The lifters have some stress markings on the sides by the axles.

I was disappointed in the head gaskets. For what these engines cost, they should be better. Some minor pinging was starting.

Re: 500 EFI Power Increase
 

I decided to do new bearings and rings. After rotating the short blocks the rings were quite. No drag at all. I am putting in the speed pro standard tension rings, I just pulled off the old rings, they were brittle and were breaking as I took them off. Block just got back from the machine shop today. Honed and ready to go.

Re: 500 EFI Power Increase
 

Linnie your motor is looking good. I wonder if your knock sensor was working with the head gaskets going?

Was the deck straight and the heads flat?

Keep us posted :drink:

Rob

Re: 500 EFI Power Increase
 

Knock sensor looked OK. Well, it was there. I plugged the computer in to the Diacom software and did not see any error codes. I think I will just replace it for as hard is it is to get to.

First motor is complete other than I had to order longer push rods.

After porting the heads the chambers cc at 122. I milled the heads .050 to get to 112cc. I used a .027 Cometic head gasket that got the final compression to 9.38. That should keep the pump gas in good check.

I was thinking after milling that much off the heads and a thin head gasket, I would have to cut off the side of the heads to get the intake to line up. These 500EFI intakes are like some of the blower intakes, They seem to be setting way down on the heads and were border line needing a 1/8" gasket. The intake lined up with the 121 gaskets without any reaming.

The lifting lugs can not be used because they use the bolt hole over the intake ports that Dart and other aftermarket heads do not provide.

I had to get .100 longer intake pushrods and .150 longer exhaust push rods to get the rocker back in the center of the valve tip.

I got Mark @ Precision to recalibrate the ECU's. Also I will be getting the second motor dyno'd the end of next week or the first following by MDG in Maryland. He is set up for Marine dyno work. That will tell me if I what I got from the mod's made.

Re: 500 EFI Power Increase
 

It is amazing how much we got done without the (Saturday Crew) Keep me informed on when you are going to dyno the motor I really want to go.

James

Re: 500 EFI Power Increase
 

Linnie Whats your deck height .Did you figure out what might caused the head gasket prob?Are you changing enything else ?


I think I am going to have to cut the the intake face on mine with the blower intake ?Mine is moving real slow :(

Rob

Re: 500 EFI Power Increase
 

Rob,
The deck is about -.020, which is standard for a 502 from the factory. I do not knot know for sure why the head gaskets did what they did. I assume it was from being just too old. When I pulled off the gaskets they were mush. I think water had been leaking into the cylinders very slightly. The GM head gaskets are really not that good for too long in a boat. Everything else was good.

Push rods fit perfect today. Just finished porting the second set of heads tonight, going to the shop tomorrow. First motor will be back in on Saturday and will fire it up. I will be tearing down the second tomorrow night to get the block honed. Will try to get more pictures.

Lets see some more posts of yours. You had a lot more to fix than me.

Later

Re: 500 EFI Power Increase
 

That reminds me I have to get a push rod length checker for the BBC.Post some picks when ya get a chance .

Linnie your moving real fast. I am kinda of slow ,but been waiting on parts and just started back on it.The blowers just showed up after being paid for for 2 months. It should come along now.I have been taking a bunch of picks and will start back to posting soon.

Let us know how the first motor does and good luck

Rob :D

Re: 500 EFI Power Increase
 

First Motor installed

Pictures of the Igloo.

Same Head gasket problem on second motor

Re: 500 EFI Power Increase
 

Notice the other head on the second engine Two valves look real white, abnormal for a EFI motor.

Pictures of parts,

Pictures of new heads assembled.

Re: 500 EFI Power Increase
 

hey linnie you know where a guy could get a nordic flame trailer for the weekend????

Re: 500 EFI Power Increase
 

Linnie that one head looks like it was blowing inbetween all the chambers? I wonder if head temp might of gotten them ,do you have a water presure gage?I am guessing :eek:


You said you were going to dyno them?

Rob

Re: 500 EFI Power Increase
 

No water pressure gauge. I do not have any water temperture problems. I have nose cones with low water pickups right under the point. I installed 120 thermostats per Marks request.

Both engines were in the same shape. They probally would have gone futher with better head gaskets. The rings in both engines seemed to be not buring oil bad but seemed wore out. When rolling the motor over, you could not hear them drag at all. I installed the Speed Pro standard tension moly file fit rings.

I want to start the first one this Wednesday afternoon if weather permits.

Second motor will be completed this weekend. Hope to get to the dyno on next Tuesday or Wednesday. 7-8 days. I decided to dyno the second motor since he was backed up a little. We head to Sarasota on March 26 for a week. Time is getting short so I have to keep moving.

Re: 500 EFI Power Increase
 

Let us know what it does . Good luck :D

Rob

Re: 500 EFI Power Increase
 

Dyno tied up next week, Maybe the week following.

Re: 500 EFI Power Increase
 

Firing up first motor tommorow night. Hope all goes well. Dyno test not looking good on the second motor. 2 weeks to Sarasota.

Re: 500 EFI Power Increase
 

What time do you plan on starting up? Can plan my day around it.

Re: 500 EFI Power Increase
 

hold out for the dyno amd try to get the ecu reprogramed . you will need it!!!
let us know :D

Linnie what kind of #'s ya looking for ????


Robster :evilb:

Re: 500 EFI Power Increase
 

JUst fired the first motor. All is good but very rich. Idled at 700RPM, but seemes it trying to stall. The ECU's are going to Mark @ Precision Today!

Re: 500 EFI Power Increase
 

Dyno guy can not get to into a couple weeks. Second motor has to go in on Saturday. They will sound good.

Re: 500 EFI Power Increase
 

Both engines are in and running. Will have to get the ECU adjusted. Thay are rich at cold idle. They seem to clear up a little at warm idle but the soot is allready there. They sound much better. Very crisp sounding. Water testing this Tuesday night. Have to buy two new injectors for the lean cylinders as they are not getting fuel. Hopefully they will be here soon.

After that I will send off the ECU's to Mark. Getting the computer hooked up with Diacom software tommorrow for Tuesday testing.

Re: 500 EFI Power Increase
 

Good luck with the test run on Tuesday. Call me and let me know how they due.

Terry

Re: 500 EFI Power Increase
 

Hey Linnie, was in VB today weather was good looks like tomorrow's even better.

Rock on!!