500 efi with a 525 cam installed
 

Ok, I just recently had my 500 efi engines rebuilt. I had the engine builder install 525 cams. They dynoed out at 524 hp and 530 hp. Put them in boat, builder also checked tune while in boat, I also installed wide band air fuel guages for both motors and that was between 11.8 and 12.5. These engines are installed in a 36 foot baja. Last year the boat with 500 efi tired engines at 556 hrs went 71 mph at 5200 rpms. Now with the 500 efis with 525 cams runs 70 mph at 5000 rpm. I feel like I went backwards and the boat should run 73 to 74 mph at 5300 to 5400 rpm. Intakes and throttle bodies are stock. Just reaching out to see what the thought is on this. I'm thinking of buying bigger throttle bodies and tune it agian afterwards. What's your thoughts.

Yes, everything was on them. And we did six pulls on one and three on the other

even used my fuel pumps

5300 rpms 524.2 HP and 4,000 rpm 566.1 torque. Yes same pitch prop

I agree with you BAJA Rooster on the props I am only running a 26 pitch prop before and after engines were rebuilt. Also if I wasn't getting enough fuel wouldn't that show up in the wide ban. I have sensors in my tail pipes to make sure its not running lean or to rich.

Are e sure the tune is spot on ? Doesn't sound so with some AFR#s in the 11.5's.

ArcticFriends just got 40-50_hp on a customers set of engines doing more fine tuning. It happens ! Thread is a few away from this if you click on "New Posts"

Yes wide open there right around 12. Through the rpm range they bounce around a tiny bit 11.8 to 12.4. 12 is perfect.

12:1 is definitely rich at wide open.

They made 524/530hp @ 5300rpms. Your spinning them 5000 at WOT. What is the hp difference between rpms? I agree that 12:1 is rich, though safe. Realistically you maybe gained 25hp per engine with the 525 cam vs 500. Prop for 5300-5400 rpms and let us know the difference.

You would probably only gained about 15-20hp over stock with the cams and a correct tune.
You most likely could have just left the stock tune and then made some very small adjustments while in the boat.
I'm guessing its a combination of the correction factor on the dyno and tuning issue.

How much total timing are you running at 100 kpa/map from 5000 rpms up?

I am Louis good friend and neighbor, trying to help him get this figured out also. One thing that I think is important here, and I have already talked to him about, is props. He is running the same pitch props, however they are a different set, on my advise he is switching back to the old props. I think it very well could be props as he is running less RPM and going almost the same speed.

I 100% agree with this. At the very least that will give an accurate baseline for comparison.

How'd it run over the weekend with the old props back on?
Very interested in the 525 cam in the 500 EFI results!
You Jet it down too?

Yes. Down 4 jet sizes all the way around. :)

Psst: Just making a funny. :)

He had a grounding/coil issue and ran with the old props, performs better than ever now, gained RPM and a few MPH from last years tired motors. Lou will have to give the specifics

That's a relief!!

I recently rebuilt my 500 EFIs with 525 cams, it was my 2nd rebuild (did it in 2012 stock), dynod in 2012, 520HP and 567 tq at 4000 rpm, now 2020 build with 525 cams 559.6 HP and 628 tq at 4000. Required an engine tune which still needs a little work in the boat but my 38 fever is running stronger for sure. With 28P bravos, ran new in 2002 83, (Reggie run it himself) and now 85!!
just an interesting mild upgrade experience I wanted to share..