Dyno vs Actual Exhaust
 

Since the complete rebuild of my 468 two years ago I have not been able to get much over 5000 RPM out of the engine in the boat. Had no problem on the dyno. Made great torque 700+ Ft. Lbs and up to 642 HP @ 5300 RPM.

The only difference between the set up in the dyno and the boat is the exhaust. The dyno used dry headers, the boat has Imco Powerflow Manifolds. Would the engine flow that much better with CMI or other headers vs the Imcos and could I lose that much HP with a wet exhaust vs dry?

My cam is the following:

Crane HR-214/325

[email protected] [email protected]
.059/104 Degree Intake
.034/114 Degree Exhaust
Gross Lift .553 with 1.7 Ratio Rockers

I'm running a Procharger at 5 PSI.

Engine runs great, just can't get the RPMs that I need on the top end.

Re: Dyno vs Actual Exhaust
 

If you remember the last thread I started about the exhaust mufflers and there claims of no power loss there were some things I didn't specify depending on the exhaust your running you may be giving up up to 8 mph which sounds crazy out of exhaust but it's true I have a very old friend in the boat business that now works at the leading performance manufacturer in Miami I can't say the brand but they have tested there own boats and confirmed the speed lost also. One good way to know if the system is holding you back check the plugs and if they are darker then they were on the dyno take the mufflers off and hang on.

Re: Dyno vs Actual Exhaust
 

Laz, what if there are no mufflers?
I got a set of Stainless Marine manifolds instead of headers.
Didn't want the risk of headers cracking and like the 5yr warranty they offer. But i will not be running mufflers. So would this pertain to your findings?
I dont think pantera28-650 has mufflers.

Re: Dyno vs Actual Exhaust
 

Have you tried any prop pitch changes to confirm the rpm loss?

Re: Dyno vs Actual Exhaust
 

What fuel system are you using and is it the same as on the dyno?

Re: Dyno vs Actual Exhaust
 

Storm I guess thats why I'm not supose to assume . Of corse I automatically thought the fuel and system were the same because thats how I run it here and also on the mufflers because they are enforced up north . I had thought after I answered many other questions such as x dimension how many blade props what pitch and so on but again assuming some things are constant with the dyno test . I also thought that was alot of power for a small engine but given the blower and boost he may be right. I still think the plug reading should give him a good indication as to if the exhaust is part of his problem. Good Luck Laz Mesa

Re: Dyno vs Actual Exhaust
 

What cam is that. Can you give duration at .050? A Procharger engine that stops making hp at 5300 is a little odd. Usually they keep making more power as you spin them faster.

Re: Dyno vs Actual Exhaust
 

Pantera
"My cam is the following:

Crane HR-214/325

[email protected] [email protected]
.059/104 Degree Intake
.034/114 Degree Exhaust
Gross Lift .553 with 1.7 Ratio Rockers"
.................................................. ..........
That is the Crane master for the intake lobe for the 721 cam, not the part or grind #. It's 276* seat (.004") and 214* @ .050
The 325 is lobe lift
The .059"/.034" is the valve lift at TDC on a 109* LSA.
Bob

Re: Dyno vs Actual Exhaust
 

Sorry, but that cam belongs in a pickup, not a boat.

Re: Dyno vs Actual Exhaust
 

I suspected it was a 721 cam. The 731 seems like a better choice for a hot 454.

Re: Dyno vs Actual Exhaust
 

No Mufflers.

The same fuel pump, filter, ignition, everything as on the dyno except the exhaust.

The cam is about the same or a little more than a stock 454 Mag.

Regardless, it perfromed on the dyno, yet not in the boat....

I need to figure this out as this is going on 3 seasons of running the motor and I still don't think its all there...

Re: Dyno vs Actual Exhaust
 

Where is your timing set?

Re: Dyno vs Actual Exhaust
 

Where is your dyno torque peak number and HP peak number?
What prop are you using?
You could be torque loading the drive which would hinder your RPM.

Re: Dyno vs Actual Exhaust
 

Las, I was wondering the same question as was posed here. Could we be losing considerable HP on my set up with those Gils over the headers you use on your Dyno ?? 50 hp loss could be costing me 1.5- 2 mph. and you know how I feel about those damned gils

Re: Dyno vs Actual Exhaust
 

Otis, I lost a motor in my Fountain because of internally leaking Gil manifolds.

I'd give Too Old a call and pick up a set of CMI's pronto! (he's got 'em in stock)

How would you feel if you ruined your new Mesa Balancing mills because of substandard exhaust?

...just my .10 :D

Re: Dyno vs Actual Exhaust
 

The cam has been installed at 110 Degree Intake Centerline.

Dyno Numbers:

RPM HP Torque

4000 542 711
4500 603 705
4800 625 684
5000 626 659
5300 642 635

It was putting aout good HP and torque at 5300 RPM on the dyno, yet won't get there in the boat. I've tried many different pitches of prop with minimal results.

Thanks for the help!!

Re: Dyno vs Actual Exhaust
 

Is your fuel system up to the task? Are you running a boost referenced fuel pressure regulator? What are you running for a fuel pump?

Re: Dyno vs Actual Exhaust
 

Is she getting enough fuel? Have you checked the fuel pressure? Does the fuel regulator add fuel pressure correctly as boost increases? What size is the pick-up in the fuel tank? Size of fuel line? Size of fuel tank vent line? What type fuel water sep. filter are you using?
Is the intercooler mounted in the same location with the same hoses and elbows as on the dyno?
I saw the pics of your install, nice job...but I noticed you have several bends in the air hose from the IC to the intake. You may be able to fit a single 180 hose or two 90's and you'll free up some power.

http://www.offshoreonly.com/forums/a...&stc=1&thumb=1

Like this M3 set up:


Do you get any belt dust after a run?

Re: Dyno vs Actual Exhaust
 

Your TQ curve peaks way too early and falls off. At 5000rpm you are off 50 lb-ft TQ and at 5300 you are off 75 lb-ft TQ! You need a bit bigger cam and a flatter TQ curve. With a centrifugal SC you should see almost a flat TQ curve and in your case around 700lb-fts. What does your boost curve look like at the different rpm's you posted above? You should be building boost with increasing rpm. If not, I would check the belt for slippage. Look at Tomcat's 500EFI dyno and boost graph. That is what I am talking about.

Re: Dyno vs Actual Exhaust
 

I just spent $2800.00 on Manifolds and it looks like my custom dry pipes are going to run another $3000.00...So, Im stuck with the **** Gils. I was against Gil, But Las insisted due to the situations we had while installing. I purchased the Danas and had them shipped to Mesa, but Las had them returned because he doubted they would work. He is the man holding the key to the 1 year warrenty on the 700's .. So I listen to him. Dont like the Gils though, because of the leaking

Re: Dyno vs Actual Exhaust
 

Bob the Gils we have are new and have the proper warranty we need for our packages I know there are other exhaust out there which out perform the gils though the Danas are not one no matter what anyone says the runner cross section will not allow for adequate flow for any n/a engine over 500-540 cubes. I personally don't know the manifolds you had were the subject of the damage of the previous engines because the pipes are also leaking. Something we also need to think about is we've found 7mph in props and exhaust we can be slightly down on power but I still think there is more to be found with a moderate chop I know we can go in the speed were looking for

Re: Dyno vs Actual Exhaust
 

Fuel System was (2) 3/8 lines to a 1/2" tee into the Wix Seperator then to the Aeromotive 1000 Red Pump then through a Peterson High flow Filter to the rail. Actual parts as on the dyno. Fuel pressure is monitored with a mechanical gauge next to a boost gauge...all is well with the system and boost reference.

Blower hose arrangement is on the engine, not changed from the dyno.

Bravo Drive 1.5 Ratio (verified)

Ran 25P, 27P, 29P Props.

Ran 82.8 with a 25P Mirage Plus @ 5400 RPM on the limiter

Ran 84.7 with a 29P Mirage @ 4700 RPM

GPS Batteries died while running the 27P

I really do not think its a prop/boat issue. As others are running the same boat in the low 90's with 600+ HP. The motor was in my 24 during this testing, not the 28 that it is in now.

Re: Dyno vs Actual Exhaust
 

How many RPM's with the 27? The differance between the 25 and 29 seems about right to me. The 27 is likely your correct prop. It takes some pretty healthy power to pull a 29 to 5400 RPM in a 24' vee. I wouldn't expect 650 to get it there. Probably not the answer you wanted to hear and I could be wrong. Good Luck!

Craig

Re: Dyno vs Actual Exhaust
 

well i am just getting into this powerboat thing, but for starters i know that with race car headers, you can print any number with different headers, some will be less hp and tq and some will be more hp and tq, but to truly find the best set you have to go test them out, because one that is down on power but will have faster mph and et times

now i know that is for cars, but im sure it could hold true with boats as well

it has to do with header length, and size, and trying to controll the gas pluses

my advance is to find out what other boats with the same engines are running and start there

Re: Dyno vs Actual Exhaust
 

If you take these #s and put them in the prop slip calc, the # seems very low. Just an observation.

prop slip calc.

Re: Dyno vs Actual Exhaust
 

Not to start a war - but I feel the need to post facts about our exhaust systems. Check the following dimensions, they are fact.
Surface area of primary at the head -
3.062" DMP Manifold
2.759" 1 7/8" tube header

Surface area of primary at collector
2.785" DMP manifold 4 ports collectively 11.14" area
8.9416" I.D. Tube header with a 3.5" I.D. pipe 4" O.D.
11.787" I.D. Tube header with a 4" I.D. pipe 4.5" O.D.

Normal tube header runner length is 15.5"
DMP exhaust have a 27" long runner length
Our primaries carry through the riser flange.

Exhaust scavenging is not well known in the marine industry. The team of nascar exhaust engineers who designed our risers would agree that alot of power is lost through exhaust. Our exhaust systems have been run successfully on several high horsepower applications, the most recent is a 920 HP blown motor in the new 27 foot Joker boat from Dana Boats. Westech dyno'd motor. We also have a boat going together with a 1200 HP PSI blower motor that was dyno'd by Paul Pfaff. That's just to name two. I have not one complaint about our manifolds losing HP.

Re: Dyno vs Actual Exhaust
 

Its my understanding that on blown applications the scavenging effect of the header is not nearly as important as it is in NA applications. Would you agree??????

Re: Dyno vs Actual Exhaust
 

Absolutely agreed, although it has no negative effect.

Re: Dyno vs Actual Exhaust
 

Ill use your phrase "not to start a war". But you really put a screwing to me on that exhaust. I called and talked to Dana himself and asked him if that exhaust was a dry setup and was assured by him that is was, I placed the order thru Trick, paid $350.00 for shipping only to recieve something that wasnt a dry set up and the finish on the manifold had scratches on it. Las and Fred were both given a difficult time when I went to return your product and to top it off I had to pay another $200.00 of my own money to ship back your mistake. Im out over $500.00 because you misrepresented your product and then gave me an attitude. I dont care how much HP loss you claim or dont claim, Im pissed off on how you handled this whole deal. This whole story and series of events can and will be backed by Fred and Las

I would absolutly love to hear back from you and see if you want to correct this problem.

Bob Scanlon
518 361-6521 24/7

Re: Dyno vs Actual Exhaust
 

The pipes are being made by Stainless Marine

$3200.00 I dont know much about nothing, but that price is real tough for me to swallow

Re: Dyno vs Actual Exhaust
 

Hey -

What about my situation?????

Re: Dyno vs Actual Exhaust
 

I'm sorry thats the way it's coming to the table. I spoke to you personally when you had the concerns about the tailpipes. Our discussion was peaceful and what I thought to be productive. After speaking with your builder we agreed to mach up one set and we were going to fabricate a set of tails to fit the boat. We agreed to exhange the tails and process the new ones as custom "S" pipe double wall jacketed pipes. We were going to charge you $300.00 more per engine. That would have put you at $1091.00 our retail price for the tails per engine. The order was placed as standard Bravo tails, which don't line up with your exhaust ports. The engines weren't even in the boat when the order was placed. An assumption was made on the tailpipe configuration. After my discussions with you and your builder I thought we had the situation handled with the new fabricated pipes. The next thing I know someone's secretary is calling me wanting to send them back. I personally tried to contact you to see why the scenario had changed. After several attemps I had no way of making contact with you or the builder. The systems came back and credit was issued to Trick. I would have been more than happy to do exactly what we spoke about and make you the dry tails to the dimensions that the boat required. Making enemies is in no ones best interest. We're not perfect, but I know how to address problems, and fix them properly. We had a problem, we addressed it, but unfortunatelty I wasn't given the opportunity to fix it.

Re: Dyno vs Actual Exhaust
 

Thiefs . . .

Re: Dyno vs Actual Exhaust
 

What kind of mufflers are you going to use? Choose Gibson's. Buy them from Fred, I'll work with Fred and he'll work with you. We'll make the deal right to pad your shipping issue.

Re: Dyno vs Actual Exhaust
 

just to comment on your comment about exhaust scavenging, you wont really see a differance at the lower rpm ranges that these boats run in most of the time

Re: Dyno vs Actual Exhaust
 

Thiefs as in thread poachers or something else?
Anyway....
How's the bottom of your hull? Any hook or deviations that could hinder performance?
What is your propshaft distance from the keel?

Re: Dyno vs Actual Exhaust
 

Ok, Ill work with Fred and take a look into the Gibsons.

Listen, I dont want to get into a pissing match at all with you or Las or anyone else for that matter. I was the middle man between your product and the builder and got stuck with the bill. I didnt understand all that you just mentioned, My understanding was that the exhaust just wouldnt work and that it was not a dry set up. I am sorry if I pissed you off. I just hate wasting money on something that was un neccesary

Re: Dyno vs Actual Exhaust
 

We're not upset. Communication is key, if we all stay on the same page, we'll get positive results. Problems happen, it's all about how they get fixed. Please do look at the Gibson line. You can view the entire line at www.danamarineproducts.com. I'm pretty sure Fred has some in stock, if not we'll do drop ships for him. We'll work it out and move forward. Your satisfaction is key in this situation.

Pantera - I think your problem is your prop. Some boats need more prop attention than others. If the 27 gets you close, you may need to modify it to dial it in. A motor performing on the dyno is good, but it doesn't mean a whole lot in the boat if the prop and X dimension aren't correct.

Re: Dyno vs Actual Exhaust
 

Fred -

I mean't thread thiefs or thieves...you know me better than that!!!

Re: Dyno vs Actual Exhaust
 

Kirk,

Regarding performance on the dyno, Angel said the same thing regarding your sexual prowess!