MILD THUNDER

iTrader: (3)

Having a conversation with a buddy. He is running a 522CI, Intercooled M4 prochargers. On the dyno, with dyno headers, the engines made 1298HP at 6500, 15lbs of boost. AFR was on the lean side on dyno.

He then installed his Imco Powerflo plus manifolds, and installed in the boat. Jetting was way fat, and they pulled out like 8-10 jet sizes, getting the afr in the low 11 range.

Personally, I would not have chosen those manifolds for a 1300HP engine. However, he's on board with going to a true header, or maybe a stainless marine gen III setup, if its worth some power. I just cant see the standard imco stuff with probably a 3.5" gas tube being near a true header, with 4" gas tubes, or even 4.5" Gen III stuff, on a 1300hp engine.

My thoughts are upgrade the exhaust, which may lower boost psi, and still make more power. Curious what you guys who have played with big power have seen as a result in this situation. Im sure these imco's are just fine on a 800hp blower engine, but 1300hp imo needs a real exhaust. Maybe I'm wrong. Dyno numbers are cool, but I don't feel the engines are truly making 1300hp in the boat. I think quite a bit less.

TunnelVision3100

Also to add to the above, the boat also went from drive ratio's 1:5 to 1:36 and I removed the -3 shortie and installed a -1in shortie... Im also thinking I loaded the engines quite a bit by doing those two things as well because I also had to change the 6/5 power valve and installed a 2/5 power valve because the boat was way too rich on the lower end

mike tkach

iTrader: (3)

Young Performance

I would agree that they are costing some power. I have had excellent luck with Hardin's Hurricane headers. They are 2.25 inch primaries, likely the same size as the dyno headers. They are made from 316 SS and are heat treated. I have used quite a few sets so far and have not had a lick of trouble.

What did the boost go to in the boat? Did it go higher than the 15 psi seen on the dyno?
Eddie

MILD THUNDER

iTrader: (3)

Glad you chimed in Eddie . Your input is highly regarded amongst our little group. Hard to say about the boost. In the boat I don't think he saw 6500rpm, but I suppose he can compare it whatever his top rpm is in boat then look at dyno sheet.

He's not happy with the acceleration of the boat. A couple guys have told him to advance the cam 4 deg and go with a 750 carb instead of the 900. He's like 252/262 .630 114 now.

Young Performance

Do you have a copy of the dyno sheet you could post? I would like to see the torque curve before making any suggestions about the cam, or anything else for that matter. If he doesn't want it posted, I can understand. Maybe you could just email it to me. If not, I can understand that as well.Some people don't want their stuff all over the place. Let me know.
Thanks,
Eddie

mike tkach

iTrader: (3)

joe b,i have the dyno sheets,imo,i think if eddie is willing to offer his advice he should get the sheets,probibally the best advice you will get.let me know if thats ok with you and il get them to eddie.

mike tkach

iTrader: (3)

for those who dont know,joe b is TUNNELVISION 3100.

MILD THUNDER

iTrader: (3)

here ya go.

Mild Thunder on the left, and Tunnelvision on the right.

HaxbySpeed

Procharged engines are very sensitive to overly rich conditions and will simply not accelerate if too fat. Because the boost curve is more exponential then linear if you can't accelerate you can't build more boost and the engine will get stuck or be really, really sluggish gaining rpm. It's very difficult to get a blow thru carb deal tuned throughout the entire curve. There's so much signal to the boosters because of the velocity that you'll often have an overly rich condition when cruising, or too lean on top if you get your cruise nice and clean. I would highly recommend to anyone running a procharged deal over 1000hp to go with EFI. Not only will it perform waay better it gives you a ton more safety. To make a true 1300hp in a procharged 522 @ 15lbs you're gonna be turning about 7000rpm and burning enough fuel to support around 1600hp. That's a chit ton of fuel to pass through a needle and seat. If you're gonna run hard at that power level you need bigger bowls with dual needle and seats and even then there's a risk of starvation or other issues when you start pounding through the waves. I've converted a few carb'd to EFI and there is absolutely no comparison! We went up four prop sizes on one with no other changes. Save yourself a bunch of money, time, wear on your engine, and frustration and just switch to EFI now. You'll have better dock manners, performance, and you can throw in some knock sensors and other safety measures to help protect your investment.