Exhaust Gains
 

What kind of gains have you seen by adding an exhaust? What kind of boat did you put it on and which engine. I am looking at adding an exhaust to a 29 V with a 496 HO and am wondering what I'm realistically going to see, maybe 2 or 3mph?

Changing only the exhaust won't change anything except your bank account. :(

An exhaust change should be made in conjunction with other changes, like supercharging. :)

As a basic rule of thumb, you should only pay for performance upgrades if you can get 1 mph for each $1000 spent. :eek:

Good luck! :cool:

The CMI's for the 496 HO's have shown pretty gains on the dyno over the stock system. They claim about 60hp, I think. Not sure if its true or not or the dyno numbers will transform into actual speed gains.

A guy with a 22 Donzi was saying he didn't gain much if anything with the 496/CMIs. I'd think 60 HP in that boat would yield at least 3 MPH.

i'd only upgrade an exhaust if the current one was shot.

I had a 454 mag 385 H/P changed from stock exhaust to imco power flo exhaust and gained 2 + mph on a 1997 22 foot scarab

Your gain was probably 1/2 and 1/2. With 1/2 of it coming from weight loss, and the other 1/2 from allowing it to breath a little better. I did say probably....:D

Or your dreammeter is not accurate:D :D

I have personally seen several boats pick up anywhere from 3-5mph with CMIs on HOs. I think a twin 496 cat picked up 9mph. One that comes to mind was a 26 Eliminator V that picked up 5mph and a prop size. Chances are you're going to pick up several mph and a really nice exhaust sound.

That was with a GPS

come to think of it my dreammeter needs to be re-calibrated this winter:D

I was thinking of changing my e-top CMIs to big tubes on my 540s, but after looking at the price I decided to wait until I really needed to change. After talking to CMI directly, even they said I probably wouldn't notice the difference.

What about Dana marine or EMI exhaust for the HO ?

First of all, the stock exhaust on a 496 isn't all that bad to begin with. Especially if you have the aluminum manifolds (as my 03 does). I picked up 2-3 mph with my Baja Hammer when I changed from stock to GIL, but the stock 7.4 exhaust is junk, so anything would have been an improvement. :D

I'll asnwer your question this way - I've modified everything from the block to the K&N intake filter and I'm running slightly ported stock manifolds.

Hey Clay, when are you going to "blow" these engines? :cool-smiley-011:

Most of the gains from switching 496 exhaust to aftermarket is from the removal of the "turbulators" that reduce the outlet about an inch. Supposed to be worth 10-12hp just for removing them. Do a search in the tech forum, there are a couple threads there. Doesn't cost anything to try.

Hey! I love a good supercharged engine. You just need to make sure that everything else will stay together, i.e. forward gear, full hydo-steering, etc.

I plan to leave my current Bullet alone. I spend most of my time with the key off anyway! :p

In the next couple of years I will step up to either a 35-foot Playboy or a 38-foot Topgun. I will have super-charged engines in my next Cig! :D

Removing the turbulators wont do anything for the feel of your boat. 8hp on the dyno, yes. Seat of the pants and GPS, no......i dont consider 1mph to be anything worth writing about. Would i go ahead and remove them? Of course. Its too easy. The aftermarket exhaust will get you mid twenty hp. Some of that from no turbulator and the rest from better flow. CMI's do sound great on the HO's, but I would go for the gusto and get the intake done too. Aluminum raylar cylinder heads, roller rockers, and cool gap intake for sure....those three with cmi's would be a nice little 500efi-like package. Dont waste money on just exhaust for these motors.

496 Exhaust
 

We are a lightning header dealer (Amongst other brands) and gave had good luck/worth while gains on the 496HO. With that said, good results/gains are 2-3MPH and a few hundred RPM.
Do they work better than stock? Yes
Do they sound better than stock? Yes
Do they add performance? Yes
Are they worth the investment? That's up to you...:D

Curtis @ Billet Marine

1 free mph sound good to me. They sound better too. I like the Raylar package, it's a well engineered kit, but combined with the price of cmi's you'll spend $10-12K per motor for 75hp. 525's are about 500pshp, and 496Ho is 425pshp. The 650 kit might be more worth it. I would lean toward whipple for the most bang for the buck. If you can make the motor live under boost. I've been hearing good things about that lately.

no....the 496ho is 425 crank hp.....even worse :(

There's alot of variables to this question, but the biggest thing to consider is the power to weight ratio.

We've installed and ran 15 exhaust kits within the last year during our testing. We've seen different results from different boats.

A 29V is a heavy boat and 43 HP is generally not enough of a power increase to have a big increase on the top end.

The reality is, it's just too heavy and 43 HP doesn't mean a whole lot. The 496 engines react very well to an exhaust upgrade on the bottom end and through the mid range, so top end isn't the only benefit.

We've spent an extensive amount of time on the dyno and on the water, and my response to customer's is that if we put their engine on a dyno, you'll have a 40-45 HP increase with you HO engine. How your boat will react to the power is a totally different question. The type of boat (cat or v-bottom), the size and weight of the boat, and the running surface of the boat all play an important role in speed increases.

One boat model we did extensive testing with is the new Eliminator 22 Daytona. We did two different installs, both with HO engines. One picked up 6 MPH and the other picked up 7 MPH. That was a light weight rocket ship that aired out very well and reacted very well to the additional power.

We just did an install yesterday on a 27ft Dana boat which is a narrow, low profile, well designed V-bottom boat for fast running. The boat went up two pitches of prop (24 to a 26 four blade), pulled the 26 four blade to 4900 rpm at 67 MPH. That boat picked up 3 mph.

I'd tell you that you'd see a difference on the take-off, mid-range, and a small increase on the top. The exhaust will become more beneficial if other things are being changed to make more power.

i hate to bring up an old post like this, but maybe some one can help here. im hearing good and bad about removing the turbulators. i want to do it as 1 mph is better then 0 mph gains. however im told do it and dont do it by many people. what is the down fall? i could care less about sound. loud pipes save lifes. lol
i keep the boat in salt water for 2-4 weeks at a time. i pull it out and flush it, clean it, spray it etc etc etc every 2-4 weeks. however i use the boat and run it pretty hard just about every night after work and every weekend so it doesnt sit in the water for long without use unless its raining etc.
id like to remove them and add some nice stainless rises for some added bling, i found a set that add's 8 hp over stock. (i know its claimed hp, like a K+N will add 20 hp. lol)
but i love the look of them as well.
any feed back would be great

ps, this is a 375 hp mag with the small cam. it is not an HO

THere is no noticable differance. Supposed to dyno an extra 8hp. I took them out of my HO in my fountain. They are there to catch water and boil it away b4 it hits the head and valves. I think put there for saltwater boats that are left in the water.....like yours. Just leave them in. Take you stock risers off and polish them or powder coat them a different color.

Don't waste your money on an aftermarket air cleaner. They literally lose power compared to the stock unit. You can hold your stock unit into sunlight and see directly through it. It has a larger flow surface area compared to any aftermarket air cleaner. It has a nice radiused venturi style air inlet into the throttle body, which speeds up air flow. Dyno test have shown power loss with aftermarket units, even on engines that have received Raylar upgrades.

What about 6.2's?

There is no cheap speed and performance in most performance boats!
 

If your boats a 375mag and you boat and stay in salt water a lot-DO NOT REMOVE YOUR TURBULATORS! Stock valves and seats will suffer (rust) and you will damage the motor! Same with 6.2L small blocks!
Stop trying to get 1-2 mph increases from minor engine modifications such as reprograms and air cleaners, they don't work! The next best alternative is exhaust upgrades with a good headers or exhaust manifold header(true header type like Dana) upgrade and work you can sometimes do to prop labbing and drive adjustments and on some boats hull bottom work. these kind of upgrades can add the 35-40hp for headers and 2-3 mph for some prop, drive and bottom work upgrades.
If you really want to add big power of 100 hp on 496HO and 150HP on a 496Mag call us at Raylar, our kits will get it done!

Best Regards,
Ray @ Raylar

thanks for the great info. im looking for cheep easy ways for a little more speed. 1-2 mph to some of us is allot, as is paying $4,000 for exhaust. if i could afford to spend thousands apon thousands on upgrades i would, but i cant so im searching the cheeper effective way to do things. im a pretty young guy trying to make a living and enjoy a sport i love and enjoy going fast. sure calling raylar would be great, paying raylar, not so great. lol
im searching for 1-2 mph the info above is saying a few things wont help, thats great info. if it wont help, i wont do it. if theres any tricks, i would love to know what i can do on a basic working mans pay check. if i had the $$$$ to spend huge coin on upgrades, i would have started off with something other then a 26 checkmate with low HP motor, but its what i could afford in the condition i want. just want to know some tips.

thanks. and if things turn around i will call raylar!! wish i could do it now

i was looking at props. i will 100% be doing that this year, any other tips to pic up some speed, top end, mid range etc etc for a lower budget?

thanks

ps, im asking these questions as i have been on boats all my life and know allot about them and the water. however i have grown up on different style boats. my dads first boat when i was born was a 22 nova 1978 i think, after theat it has been all cruzer boats. 32 st tropez, 36 tiara, and now a 37 riviera. im just getting into messing with the go fast, so im a newbie looking for info.
thanks.

Noyzee,
There is no cheap performance gains to be had. My 28 ft Silencer is in the process of getting Raylar's 103 kit installed as we speak. I had to pay an additional 30% due to the Canadian exchange so I Know its expensive. The boat better work with the 100 more hp!!!
What you are looking for could probably be achieved by running good engine oil, proper air flow, a good prop and alot of time spent on your back waxing and polishing the hull....theres 1 mph with the wax....
just my .02

I had an older 26 stinger with 350/375hp. I added the stainless marine exhaust, took the bottom paint off. I gained 6mph. On a GPS.

Not sure what got me the 6mph but I think a combo of both. I heard taking the bottom paint off adds 2-3 mph.. I think the exhaust definately lightened the load. ( From Merc cast to Stainless marine alluminum) I truly think I gained a few MPH with the exhaust too..

True, but you also need to add a lil disclaimer here about the increased dangers that come along with their removal.

sounds like a prop for this season and the rest will be the bling. i already wax the hull but it seems my boat runs the same no matter what. ive put it in the water, fresh waxed hull, clean as can be and smooth. 1/4 tank of fuel, nothing on the boat just driver and some basic stuff, cool air and perfect water. the boat runs 60mph on gps.

i have then taken it out, heat of the summer 3/4 gas, 2 people, a cooler with beer and 2 weeks of salt water growth on the bottom and the boat goes 59-60 on gps.

i then had 7 people, 90 beers, 3 coolers, food coming out my ears, cloths, an inflatable boat in the v-birth fully loaded, full fuel dirty bottom etc etc etc and the boat still did 58 every time and 59 running with the wind on the way home with a little less fuel and a tad cooler air. its strange, but the boat runs the same pretty much all the time. lol seems fully loaded i can trim it up more tho befor the prop starts to spin so maybe that is the key, getting the boat up more with a little more prop.
i'll find out, im going to be calling todd this week to place my order.

A new E-Top for the 496/GM Big Block
Released at the recent LA and Miami shows, replaces the stock height riser exhaust and fits to original tail system or silent choice Y pipe diverter. CMI system at competitive to cast aluminum pricing. Fits 34.5 centers.Attachment 378050