Big Power exhaust systems
 

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.

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

:food-smiley-007::food-smiley-007::hitfan:

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

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.

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

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.

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

here ya go.

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

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.

He did have to step up to the dual needle and seat bowls. On the dyno, it would suck the standard bowls dry right at top end of the pull. His regulator is referenced. His idle quality around the docks sucks, and being a staggard boat isnt helping docking.

What you say makes total sense about the EFI!! Ive always been a cheerleader for carbs, mainly on roots stuff, and N/A, just because its simple, and Im stupid! However, there really isnt anything simple about a blow thru carb setup, learning that pretty fast!

At this point, maybe he needs to look into EFI, rather than spending the dough on some new exhaust. Maybe a little less cam duration. It probably be sooooo much more user friendly, and safer.

joe.are the inner cooles force fed from lwp or from the engine? also 2 idle if the carbs are too cool the idle will suck..

BTW if he ic comparing his boat to mikes then it will never accelerate....tell him to put # 6's on his boat and then take it for a ride..

fixx,the innercooler is fed from engine cooling water,if its running,cooler is getting fed.btw,3.13 am,dont you ever sleep?

fixx
 

theirs part of his problem,,if he lets the coolers warm up a little by using low water pick up feeding the coolers they will warn up a bit so the holleys are not so cool when docking..you knoe how cold harted holleys are lol...Btw ill get plenty of sleep when im 6'under..:lolhit:

i think efi will cure all the problems.

Plus with that big chiller plumbed in, that thing is friggin ice cold to the touch!

I think I mentioned trying disconnecting the water supply from the chiller and plugging it just to see if it helps at idle. I dont believe Tunnelvision tried that. I know it didnt seem to make a difference at idle on the dyno when turning the water off, but the motor also wasnt loaded at idle on the dyno, like when in gear in the boat.

I agree, I think EFI would be money well spent on this setup.

it would be easy to plumb in a checkvalve for the innercooler,i have some in the shop,but i dont think it will make much of a difference.

are you sure they are not leaking and its drowning the engine with water?? First thing i would do is pressure test the coolers who knows maybe thats why the afr's were off also..

Joe,then have the crank and charger pully notched abd add the extra support on the brack so it dont bend whyle in boost mode and drill the plate and add the pullys we talked about..

I have to agree with Haxor. He pretty much nailed it on the head. If that engine had a 5L Whipple, it would be making about 12 psi of boost at 3500 when loaded that hard on the dyno. Plus, it would have had about 300 more ft lbs of torque at that rpm.

I spoke with Mike today for quite a while. While we were on the phone, I pulled out a dyno sheet from the 598's w/ 5 L Whipples to compare the numbers. Mine made 1291 hp at 6100 rpm with 10.9 psi boost. They made almost 9 psi boost at 3500 when the pull started. They made over 1100 ft lbs the entire pull, from 3500-6100. At no point did it go below 1100 ft lbs. Peak torque was at 4500 at almost 1200 ft lbs.

I mention all of this because it all goes back to the root problem. The engine isn't making any torque down low, primarily because it isn't making any boost. Add an overly rich condition, a cam that may or may not be correct for a Procharged app and you end up with a lazy bottom end. I would bet that the smaller exhaust is probably helping a little with the bottom end right now. If you were to put larger, better flowing exhaust on it now, the getting on plane issue would be worse.

I am by no means an expert at blow through carb setups. As a matter of fact, if someone would have come to me wanting that exact engine, I don't think I would do it. I would only do it in efi at that power level. Converting it to efi would be the best move to make at this point. I don't know that it will solve all of the problems, but it sure will help.

The X dim. sounds like it's pretty low. After Mike gave me the rundown of the height changes, I think it is also a big part of the problem. When the boat was built in '96, they were pretty conservative with drive placement. The boat would probably really take to a set of SCX -4's. It only money:lolhit:

It was really good talking with you Mike. Give me a shout if I can help.
Eddie

eddie,you spoke with joe today[tunnelvision3100],he was going to call me and put the 3 of us on a conference call,but i guess he forgot about me.

i put the xtra idler pullys on last year,can you explain the notching of the pullys.

Yes, I spoke with him for probably an hour. You, or both of ya'll, can call back anytime. I would be glad to help in any way I can.
Eddie

fixx
 

check this pic out to give you a idea...http://www.454ss.com/cgi-bin/forum/Y...num=1123264006

sounds like he really needs a cog set up like what on the f4 set up..http://shop.brutespeed.com/ProCharge...lleys_c695.htm

if mike really wants faster acceleration he will need to limit the rpm he is spinning his engine and drop to a smaller crank pully so the blower will spool up faster..changing the blower pully will only cause the belt to slip more..

my buddy has a f3 on his wifes prostreet mustang,,we were at a race in bradinton fl and she complained that the car was not leaving that hard so i put a smaller pully on the charger,,well when she let go of the trans brake the car stood on its back bumper..now thats acceleration...

BTW prochargers really dont like huge cam lift or duration so what eddie is saying is vary true..

i have not done this ''yet'' but on gina's mustang i am going to remove the bracket and install another tensioner on the lower side of the belt..