Dyno Results
 

Hey All,

Posting the results here because this is where I usually see them. If it should be added to previous build thread instead let me know. Well, here are the results finally. I've had them for a bit as you can see the date but have been putting long hours in so not spending too much time on here. Engine static compression is: #1 9.1:1, #2 9.02:1. #2 was dynoed first which was a little disapointing with final power numbers. When #1 tested higher the shop switched fuel pump, carb, and distributor between #2 and #1 to see if #1 would fall and it didn't. after multiple pulls and long discussions we decided to leave as is.

2 tests on water so far. First time out flooded pretty bad and day was over after being towed in. Took carbs apart and they were dirty. After a good cleaning no more fuel dumping into carb.

Second trial just this past Sunday was better for the most part but still some issues. Get out of the no wake zone and pick it up to 3600rpm and hold for a few min then shut down to take a look in engine bay for any visual issues, saw none. Then decided to WOT but maxxed out at around 4300-4400 rpms, noted. I shut it down at our destination and we spent a few hours on the beach before deciding to run the boat for a while nonstop. took off and cruising at 3800rpms at 43mph (phone gps) until we smelled burning rubber. Shut down and opened hatch to see a hole at top #2 inner exhaust hose. I have exhaust tips a little lower to clear the swim platform and the inner gas tube of the 496 riser flares out, might have to grind out the flare to keep it away from the hose. Ended up limping back to marina on one engine for an hour. Haven't done anything since. Looking to test again on Sat. This time without the lady so it's not a test/fun day and taking all equip and checking/setting time while out on water instead of driveway and pulling plugs for readings. Forgot to mention that when we shut it down after the burnt hose there was a few seconds of "run on" or "dieseling".

Currently, carbs are Merc blue 800cfm that I bought from the classifieds. should be off a Merc blue motor, right, with the staggered jets and 6.5PV in primary? Well, both are 85 jests squared and no power valve. Could my low rpms be due to not enough fuel at WOT? I usually see people here running 92 jets in secondary.

[ATTACH=CONFIG]525620[/ATTACH][ATTACH=CONFIG]525621[/ATTACH]

At work so I'll post more later , but 85 jets squared with no power valve seems light .

The stock 420hp 454 used a 800 holley , with something like 80/90 jets with a 65 power valve in the front .

I bench setup a couple carbs for a buddy two years ago. 454' S with GM rect ports, 236/245 114 LSA cam, single plane intake, nothing crazy. I believe I installed 82 front with 6.5 pv, 92 rear. That was the baseline. I figured it would be a little rich but rather start rich and lean down from there. Upon installing in the boat, afr was around 12.2 at cruise. At wot it was low 11's. A bit rich for a N/A engine, but it was a warm day when we checked it, and he loves holding the throttles pegged for miles and miles. Left it that way. I do need to get with him though as I'd like to jet it down a tad for him.

Are these the same props you had last year, and If so how many rpm did u previously spin them to?

Since I have not PV should I leave the 85 jets in the primary? I will probably get some bigger jets, 90-95 tw swap out this weekend on the secondaries.

Same props. last year the motors were spinning 4600 WOT.

Just noticed the ''dieseling" at shutdown. Yikes. Thats not good.

Put some fuel in it before you hurt em. When you add up the jet diameters and PV channel diameters, of what merc used in your carbs on the 465HP 502, 420HP 454, etc, it comes out to be around .485''. Currently, with the power valve plugged and 85 jets front and rear, you only have an overall diameter of .394" when you add up the jet hole sizes.

This weekend, I'd start with this setup.

Install a 6.5PV in the primary. Leave 85 jets for now.

Install 92 Jets secondary. Leave PV plugged.

I'd be sure you have some sort of fuel PSI gauge, to make sure fuel pressure isnt dropping at wot.Then start pulling some plugs.

What are you running for fuel lines/pumps btw?

[ATTACH=CONFIG]525627[/ATTACH]

Here's a pic of motors installed. I've since added a fuel gauge at the carb on the port side as well. I was going out on Sat alone so may be a difficult to rubber neck at the gauges while at WOT, scary. I'll figure someting out.

Just talked to speed shop and i'll be getting some new gaskets, 6.5PV, and 92 jets tomorrow. Fuel lines are -8 and running the holley 110 mech fuel pumps. On dyno the fuel pumps held good pressure but now seeing the diffeences betwen dyno and actual.

The fact that you burned an exhaust hose also makes me wonder if you were running it lean. Exhaust can get pretty hot when that happens.

Question: Why didn't they get A/F readings during the dyno runs? That would have helped to get you in the ball park. Also, I had them run a steady state test on mine while it was on the dyno for several minutes from 3800 - 4500 RPM's. This revealed that it was leaning out under a fast cruise. Keep in mind that the big 50 cc accelerator pumps on the marine Holley's can mask a lean condition when they are doing a 300 RPM/second dyno pull to WOT. The engine is only running under load for 10-15 seconds when they do this.

OK, I see now that they did BSFC instead. Did they dyno it with headers or your wet exhaust?

They dynoed with their headers. They did do A/F reading I just don't have them in my folder, the shop has them though. That's my thought exactly with the hose burning which is why I'm now trying to figure this out. I will, however, still check the downward angle of the exhaust hose in relation to the flare on the risers. But i'm surprised that it didn't happen to any of the other hoses.

I just got off the phone with shop and letting him know all this and we went over some paperwork and the sh*t gets a little thicker.....my carbs don't have even a provision for the power valves so should I jump up the primary jets to near 90 withe 92 in the secondary?

Ugh....no pv circuitry....wth.

PFFT. Yea, I'd prob go 92 square then...maybe even a tad more to start....SMH. :cartman:

Can you post up the specifics of the build again for us? Whats the Timing set at again?

Yep, no PV. I got these carbs from here on classifieds, a little disapointed in that decision right now. I'll post the specifics in a bit, currently at work and need to get some stuff turned in.

Here are the build specs:


Brodix Race Rite Rect port alum heads
Stock 454mag gm aluminum intake
Marine Kinetics custom cam: 613in, 598ex on 114 LSA with 4-7, 2-3 swap

Let me know what else is needed to know.

How come that oil pressure is so high?

I noticed that too. That's going to put a lot of strain on the distributor gear.

I would think that you are losing a lot of your power with those old school manifolds. A set of Air Gaps or Dart / Victor Jr single planes would probably wake them up to the tune of 15-20 HP, especially with those heads.

I don't see where you listed the displacement of the engines.

Also, post up the list numbers from those carbs. Wondering if they are really HP500 carbs, or even 800's. If they are, and there are no provisions for a PV on the primary side, then someone has definitely fucqed with them.

My oil pressure was over 100psi on the dyno. However, I was not running thru the remote filter/lines and the oil was a little cold yet. In the boat I see about 75-80psi running, 50ish at idle. My oil pump was shimmed for a little more pressure. Prior to me going thru the engines, I only had about 50psi max with the old setup. Not enough psi at 5800-6000rpm imo. Pulled distributor gears this winter, gears still look new after 2 seasons on them.

I think Eddie Young runs similar pressure in his engines with no issues I know of.

Whats the total timing set at Ramos?

those are nice numbers trucker:picard1:

Roger that ...... :readinghelp:

Budman look at the bottom of the dyno sheets..one reads 467 and the other reads 460 cid..

intakes are hurting him,,cant flow the cfm he needs for his cams..

Just got back from movies.

460 and 467 are the displacements. Oil pressures in boat now are 85-90 running and idle around 70. Even before rebuild the oil pressures were high but without issues for the time I've had the boat. I'll get to the boat in the morning before work to get the carb list numbers.

I'm using the th 4 ignition so until it's set at 8 and total is 32. I have a new digital timing light coming so to recheck it all. Going to get new jets tomorrow to prepare for weekend. So 92 squared should be what I start with?

I'd probably be bumping that timing a bit. 9:1, aluminum heads, more agressive cam, short stroke, I'd prob be shooting for 34 at least, maybe 35-36. Did you guys play with the timing on the dyno?

Its common in the car world to pull timing back for a safety margin. In marine engines, doing so, can lead to high exhaust temps, tuliped valves, etc. I woulda been giving it some timing on the dyno to see what it likes after getting the AFR close to where I wanted it.

It almost kinda sounds like you didnt get your moneys worth on the dyno session. I think the whole reason to dyno, is to get a good tune, rather than power numbers. If he didnt give the engine the fuel it wanted, timing it wanted, etc, than its kinda a waste of time. Its not usual that you remove a properly tuned engine off the dyno, install it in a boat, and then have to ADD more fuel. Usually if anything, you'd need to remove a little fuel when in the boat. The BSFC numbers on your sheet look all over the place, I'd like to see what the 02's were reading. :(

I couldn't be there for both dyno sessions. I know he told me he did try spacers but they made things worse and he checked the jets to know what was in there. They switched out carbs, fp, distr to try and identify the power difference between the two engines but all still the same. Also due to lack of communication, they had the timing locked at 32. They didn't have my TB IV ignition module so they used their dyno stuff. When i went to check the timing i noticed it way up and had to bring it down due to the 24degree advance in the module.

Should i set initial timing at 10 and let the module do the rest or set to total of 34 at a certain rpm and let the initial fall where it may?

While on the dyno we discussed trying to simulate cruising speed but the dyno just can't do it. it's WOT or nothing, he tried but it wasn't worth it. From reading on OSO I've always seen that they way the motor reacts on dyno is usually different than what you see in actual boat due to cruising loads and actual resistance due to weight of boat. This leads me to believe that even thoughit dynoed ok with 85 jets it's no wonder I need to step up the jets due to the extra load present in the boat. I'm still trying to learn all this stuff and apply it so I appreciate all of you guys taking the time to give your thoughts on this.

Joe,

I know this isn't the same but I wonder why merc pulls timing on NA 350 MPI Mags at 3800 rpm's from 32 to 29 and at WOT it's 27. Most guys I talk to with NA dyno experience say the HP / Torque gain is minimal with more timing. But these are street NOT marine guys. Hard for me to believe that though. I know Vortec heads burn pretty quickly but saving the exhaust valves from unnecessary abuse and gaining some HP makes sense to me.

For entertainment purposes I've attached a tune screen shot video that is currently being edited by youtube. Info starts at 4:20 mark if the edit hasn't completed. Headed to the Lake to pull idle fuel and add top end fuel now. Cam change...

https://www.youtube.com/watch?v=8dPHaOpAFLI Andy

Im not too familiar with the SBC stuff andy, but its all relative in a way. The fast burn chambers simply dont require nor allow, as much timing as your typical open chamber head. When you get into reshaping the chamber and the way the whole burn process goes down, it alters the entire combustion process.

Sort of similar when you get into different piston shapes and dome sizes and what not. I wouldnt recommend 36* of lead with a fast burn chamber marine deal. It all pretty much boils down to having the most efficient combustion process inside the cylinder. Generally speaking, if you light the combustion off too early (more timing), you can see an increase in power from a higher cylinder pressure, but also, too early and you could get preignition, or detonation if the cylinder pressures exceed the octane level fuel being used, which we all know is not good. Light the combustion off too late, and you can get away with a little more, but the power will be reduced, and the exhaust temps can get hotter. Finding that happy median is the goal.

I see lots of guys on the street stuff, pulling a bunch of timing, so they can run more boost say on pump gas. Which works in their application. But, they arent holding the throttles down for 15 minutes either, let alone even 15 seconds. I'd like as much timing as my combo will allow (octane, boost, cam, compression, etc) , without getting into preignition.

There is an area of the RPM band, that timing can usually be pulled from, or should be pulled from. And that is at Peak Torque. For example. A BBC marine build, might like 35* at 6000RPM. But, around peak torque, 35* might get into trouble. So for years, before we had any fancy ignitions, guys simply lowered the timing all together. Now they have stuff out, even for carb'ed engines, that you can map the curve, so that maybe you'll have 36* at 3500, 30* at 5000, and back up to 36* at 6000. Generally speaking, i think of ignition lead, as more of a tuning episode for a healthy engine, more so than a power adder. Giving the engine more timing in a quest for power returns, usually results in meltdowns. Retarding it in a quest for "safety margins" can also result in tuliped exhaust valves, etc. Also why inconel, or ferrea super alloy exhaust valves are so popular in marine, even N/A marine stuff. Simply put, the exhaust valves get fukin hot.

Most of this stuff is better answered by guys like Eddie Young, Alex Haxby, Bob Madera, and other guys much more knowledgeable than me. Im just a truck driver!

I know I have been called out on this before by someone saying that BSFC doesn't matter, but everything I read is from 0.48-0.55 on a NA engine. (mine are 0.52) his look extremely high. What are the AFR #'s?
My 454's are 76 primaries and 82 secondaries with 6.5PV's at a 12.6-12.8 AFR's for reference.

Well with all this good advice, not to jack his thread but, I have a question myself! I just had a new motor built and don't want to see any problems down the road! My machine shop mainly does race car motors, and has done quite a few boat motors but does not special in boat motors! How ever we dyno'd it at a mild pull at 36* timing, 579 ft tq @4200 and 530 hp @5500 finial pull ended at 38* timing, 582 ft tq 550hp, @5500! All with a 800 cfm hp500 Holley 82 front 92 rear 6.5pv! Msd programmable box and msd dizzy! I've ran the boat twice but y'all kinda worrying me with all this timing stuff! So my Q? Is? I'm only running it at 36* right now and not sure I should put it where we dyno'd it at peak, bump it up or down are just leave it alone! Or pull a little out around the highest tq numbers and bring it back in after it starts to fall off! What do you guys think? It runs good just want it safe also!

Carb should have a provision for a PV. Check both just to see if other carb has two.

The possible ding dong who owned them before could have put two primary metering plates on one carb and two secondary plates on the other.

I have never seen a 4150/4160 carb without atleast one metering block with a PV provision. With one provision, it will be in the primary metering block.

Those Brake Specifics (BSFC) are horrible !!! Both sheets, #2 sheet being the worse.At some points your #2 sheet is looking like a 2 stroke is being dyno'd. IE: in the 9's.

Rookie is correct in where most BSFC's fall.

Remember, BSFC show's how much fuel is being used for each horsepower.

Sorry, but your's are junk. No effort was made to tune these engine(s).

Was tuning part of the agreement for the dybo test - some places don't get involved and some do. Some do for extra $$$ and some don't. This always needs to be discussed when setting up a dyno session.

That's what I was thinking. Washing those cylinders down.

I agree the bsfc numbers are awful. My assumption was that they were not true bsfc readings.

When you run a boat and go to shut it off and it "runs on " or "diesels" it's way hot in the chambers. If the fuel was that rich as the bsfc numbers show, I can't see that happening. It's all guessing without afr numbers or even plug readings at this point.

Rookie what size are your carbs ?

Fuel dribbling out of the boosters or vents when idling will cause run on. This would be caused by too high idle speed/throttles open too far or too high fuel level in bowls.

Got jets switched out today and yes, I do have provisions for power valves in all four blocks. Now that I know what to look for I can see they are blocked. Don't know what shop was talking about. Ran out of time to run it today, will get it tomorrow. Also, I'll try to get the afr readings from shop next week. Thanks all for all the advice.

I'm sorry I just gotta put this out there I've been following your post for the last few days but whoever dynoed your motors did absolutely nothing for you. I mean with the end product what was even the point of dyno ing them? Will the motor come off the dyno and be 100%...? No, but it should be alot closer than where you are at right now.

Black Bajax I'm starting to see that as well. This guy definitely can build them but it seems as if he rushed the dyno.

All, I understand that I should be adding more fuel by increasing secondary jets and adding per valves but wouldn't this also increase the BSFC numbers and make them even worse?

Generally i would never enter into a conversation of this nature...but soo much money and intelligence has been been shared...perhaps some thought is needed. First i have been rebuilding carb's since 1968 and gleefully thought they were things of the past....anyone who ever thought they were a godsend is mentally deranged. Get some new carbs and then jet...there was a reason they were on ebay or craig's list......Plz someone of high credibilty come in and post as to how all the circut's work and how one can be overlooked by the best...messing everything up...carb's are extremely complex.

It would be a lot of typing to get into the works of a Holley. For a good overview, go to Holley.com. Go to the technical page. They have a section called A Look Inside Your Carburetor. There is some other good info on the site as well.

There are some decent books for Holleys out there. One of them is by Dave Vizard, How to Tune and Modify Your Holley. This book was published in 2013, so it should get into the newer technology. I have an older version of a similar book and have from personal experience found that the basics are well explained, but the technology has changed drastically since the book I have was published.

I have yet to see a Holley book for Marine applications.

Once you learn to understand the functions of the circuits, Holley carbs are pretty simple to work on.

I got to the lake early yesterday to tune everything before "Sunday fun day" started. Idle is set to right around 800 pulling 13-14in vaccuum. Initial timing is 12 with total of 36 coming in at 3800. 32 degrees at 3000rpms. 85 jets in primary with 6.5 power valve and 92 secondaries. I found the power valves and a local Orielly's but I didn't check for jets. Here are #2 plugs from each motor. Think I'll step down the primaries to 80 and see if that cleans up the plugs some.

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Make sure you put in a new set of plugs and check. Doesn't take much to foul a plug and a fouled plug will give you a bad reading... What rpm were you at when you shut the motor down and pulled the plugs?

My carbs are old Barry Grant's that were built off Holley's. They do have "BG" cnc'd on them. If you go by Holley #'s they are 750's. But, my unscientific experiment says they are larger. http://www.offshoreonly.com/forums/g...-saturday.html

When Tom Earhart dyno'd my engines, that's when I learned about BSFC. I was originally in the 0.63 range and he was telling me I needed to pull some jetting out of it. These just came off my 420's. I guess with my new heads and cam upgrade the carb signal was greater and pulling harder on the jets at different throttle positions.

A friend of mine must have spent half the summer piddling with plug readings on his 502. With the oxygenated fuels we have to run in our area it is nearly impossible to get any color on the plugs. You have to make a full throttle run and then immediately pull the sticks back and shut her down. He even swerved around the opposite way to keep his own wake from inundating us. Letting it idle for any length of time will give you a false reading. This is one of the reason that so many have moved on to installing bungs and taking A/F readings with a wideband O2.