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.