Torque & HP Open Discussion |
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Hollywood
Moderator Group Joined: February-04-2004 Location: Twin Lakes, WI Status: Offline Points: 13512 |
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Alan, what has gotten into you? You can still ski, plenty of "golden" years to do all that engine stuff.
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81nautique
Grand Poobah Joined: September-03-2005 Location: Big Rock, Il Status: Offline Points: 5772 |
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Thinking about this exhaust a little more, without scavenging, the engine is relying solely on the exhaust stroke of the piston to push the gases out of the cylinder. This also has an impact on the engines ability to refill the cylinder with a fresh charge of intake mix. Scavenging in combination with valve overlap could be the biggest factor in get air/fuel and spent gases through our engines. Scavenging creates the pulse and overlap allows the intake and exhaust valves to be open at teh same time using the pressure of the outflowing gasses to draw in fresh air/fuel mix. If that effect is being limited then the focus should still be on the exhaust.
Seems to me we need water jackets headers for a ski boat. |
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You can’t change the wind but you can adjust your sails
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81nautique
Grand Poobah Joined: September-03-2005 Location: Big Rock, Il Status: Offline Points: 5772 |
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While flow of the exhaust system is one concern another major factor that will not be overcome with stock manifolds is that they are considered a Non Tuned design meaning no pulse or suction waves are produced so there is absolutely no scavenging effects to help evacuate exhaust gases from the cylinder. You would need to get into a header/collector design and I don't believe even the hiteks fall into this catagory as they are not long enough. So restriction may not be as big a detriment as overall design. Let's not forget about the water in those 3" pipes and the effect it may have as well. |
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You can’t change the wind but you can adjust your sails
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41040 |
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Joel, Very good point!! With some CFM figures, it's very easy to look on the graphs or calculate the restriction with different lengths and diameters of "tail" pipe. My graphs will show restriction in inches of water (manometer reading). I'll take a look to get a rough idea. The major unknown however will be the effect of the water in our wet exhausts.
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M3Fan
Grand Poobah Joined: October-22-2005 Location: United States Status: Offline Points: 3185 |
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Although the riser area is a bit restrictive doesn't the length of the restriction become a factor as well? For example, an automotive header may be less restrictive at the collector but then you've got 2" exhaust going all the way back to the rear of the car with twists and turns, cats, mufflers, resonators, etc. With a lot of these boats you've just got 10 feet or so of 3" hose and nothing else to restrict flow after the riser.
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2000 SN GT40 w/99 Graphics/Gel
2016 SN 200 OB 5.3L DI https://forum.fifteenoff.com |
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81nautique
Grand Poobah Joined: September-03-2005 Location: Big Rock, Il Status: Offline Points: 5772 |
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Cool, I'm really interested to see how these things are shaped. Please send both halves if you can. I have a neighbor at my shop that does hydraulic flow testing for nuclear power plant cooling systems and started a conversation with him yesterday about the manifolds and he said once I remove mine for the upgrades he could help me set up a flow test on them. When I was in the window industry I had to take a sampling of each of our products to a test lab annually so we could have water and air infiltration tests performed for certification so I have a pretty good idea of whats going to be needed to do it. Should be fun putting the rig together. |
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You can’t change the wind but you can adjust your sails
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Waterdog
Grand Poobah Joined: April-27-2006 Location: United States Status: Offline Points: 2020 |
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Alan
I pulled the manifolds out of the barn last night. Need to remove the risers and throw them in the trunk. We have a 20 in cut off saw at work for sectioning aircraft parts during engineering investagations. Maybe over the weekend I'll come in and cut them up. |
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Sabre002
Groupie Joined: July-18-2007 Location: United States Status: Offline Points: 53 |
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This program is great I showed it to Reid a few years ago I have sense got a new version and you would not belive the thing it will let you toy with.
I have used it to build my LS1 and it was right were it said it would be. |
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So what winks and f**k's like a tiger?
www.facebook.com/sabre002 |
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81nautique
Grand Poobah Joined: September-03-2005 Location: Big Rock, Il Status: Offline Points: 5772 |
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That will work Andy, do you have a bandsaw at your disposal? I wasn't really looking forward to tackling this with just a sawzall. |
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You can’t change the wind but you can adjust your sails
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Waterdog
Grand Poobah Joined: April-27-2006 Location: United States Status: Offline Points: 2020 |
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Alan
I'll get those exhaust manifolds out of the barn & put them in my work car. I'll cut 1 if I like it I'll cut the other the same and ship it to you. Probably just the inboard half to cut down on weight. Could you donate the cost of shipping to the club ( CCFan)? |
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GottaSki
Grand Poobah Joined: April-21-2005 Location: NE CT Status: Offline Points: 3335 |
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most excellent. look forward to it. Likely those heads will like more cam lift than you are used to seeing. Most windsors reach deminishing returns above .45", but it appears the canted valves really open up and get away from the cyllinder wall from .45" on up and the flow continues to climb in earnest. |
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole |
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81nautique
Grand Poobah Joined: September-03-2005 Location: Big Rock, Il Status: Offline Points: 5772 |
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That's what I was thinking of doing so we could get a look at the runners up to the riser. I also plan to port match mine when I get my heads in so I wanted to see how much material there is to work with. |
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You can’t change the wind but you can adjust your sails
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Waterdog
Grand Poobah Joined: April-27-2006 Location: United States Status: Offline Points: 2020 |
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Alan
I've been holding on to a set of cracked exhaust manifolds, to cut open. Would you cut it front to back, thru the center of the pipe plug holes on each end ? Just wondering what would be "best". |
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81nautique
Grand Poobah Joined: September-03-2005 Location: Big Rock, Il Status: Offline Points: 5772 |
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GottaSki, I'll play around with that in the next few days but I'm sure I'll have some questions so stay tuned.
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You can’t change the wind but you can adjust your sails
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81nautique
Grand Poobah Joined: September-03-2005 Location: Big Rock, Il Status: Offline Points: 5772 |
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AFR185/RHS180 flow comparison
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You can’t change the wind but you can adjust your sails
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GottaSki
Grand Poobah Joined: April-21-2005 Location: NE CT Status: Offline Points: 3335 |
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Now If someone were to comit to both fancy heads and hi-teks, that begs the question - "why stay with the hindrance of Windsor-style heads"
Quest for speed opens the door to make a clevor. The sb Hi-teks are the same price no matter the port arrangement, so its a chance to start fresh. Please use your calculator to see the potential in using CHI 3V heads. They are available in Alloy and Iron, and three different port volumes so the low end won't suffer as much as you think and the canted valves really boost breathing. Yes, different pistons are in order to optimize the whole package but that could be rationalized. I think its a worthy exercise. I predict you will be able to exceed the performance above and be able to keep the CR in a more practical range for pump gas. |
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole |
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81nautique
Grand Poobah Joined: September-03-2005 Location: Big Rock, Il Status: Offline Points: 5772 |
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Mark,
Here are some graphs for engine both current and with the mods you mentioned, I also added one with the RHS heads I'm going to use. Without having the exact cam specs what I did was put together a stock 351 and then make your changes to it like CR and intake. There are no provisions in the program for marine exhaust so the reports I will email you are going to show stock exhaust with mufflers but the only other selections are open headers. All of the models so far have used the same exhaust options. There are no provisions in the program to add the underdrive pulleys. MM's 351 as it is currently, 9.7CR,stock cam, 1.7 rockers, stealth: MM's 351 with the AFR185,10.5 CR, .470 cam, 1.7 rockers, stealth: MM's 351 with the RHS180,10.5CR, .470 cam, 1.7 rockers, stealth: This one is a side by side: If you want anything changed just let me know, you might want to really take a good look at the RHS180 heads. I found that out of the box they flow better than the AFR and are less expensive although you'ld have to decide iron over aluminum. I think the real answer to your question is will a cam and head change add 75-100hp and it appears that it will. Better install some grab rails in that machine. |
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You can’t change the wind but you can adjust your sails
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reidp
Platinum Member Joined: December-06-2003 Location: Mooresville, NC Status: Offline Points: 1804 |
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Sorry I'm late. Couple of things from well up above. In regards to me thinking the risers could be a bottleneck, my thoughts were from this: My aluminum Barr manifolds on my blue '69 302 have 3-1/2" risers, and they perform very well comparitively. Port openings on the manifolds were enlarged by me, but mainly the outlets on the risers are larger, falling in line with what Matt above suggests as critical. On the PCMs, the outlets, just like the manifold-to-riser passage are significantly cut down.
These are some good and thought-provoking points above which will make for some really interesting conversation. Alan, I'd like to feed you some cam/head combo info for a good solid 302 build-up also. I'll try to do a PCM/HM/Hitek comparison some time in the not too distant future. |
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Ben#155
Senior Member Joined: June-24-2008 Status: Offline Points: 228 |
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[QUOTE=81nautique] Matt, Here's a graph based on your specs. Some of the input is guesswork but I think it's fairly close. Seems to match up pretty closely to a gt40 280 hp motor. Do you have flow data on the heads? Shoot me your email address and I'll send you a pdf of the report, if you want to change anything just let me know.
[/QUOTE I tryed 3 inch headers but there was not much difference! I think stock manifolds has much torque and that is what you need. |
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81nautique
Grand Poobah Joined: September-03-2005 Location: Big Rock, Il Status: Offline Points: 5772 |
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Joe, A final note before I get to work today. A while back I set up a simple spread sheet to calculate prop, slip% based on known data including RPM, MPH, prop pitch, & trans ratio.
My boat currently runs 52.6 on GPS at 5300 rpm, with my 540 prop with the added cup that calculates out to 16.16% slip. If the slip percentage holds true and I could possibly turn the motor at 5700 the speed comes out at 56.5 mph. Several unknowns there such as will ssip stay the same and will the engine actually turn 5700. I think 5700 may be a stretch. If I change props to the 13x13 the spreadsheet shows it should only need to turn 5500 to get to 56.5 mph. Experience to date still leads me to believe that will be a challenge also. I firmly believe I will need exhaust work to do that and possibly a taller cam. |
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You can’t change the wind but you can adjust your sails
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81nautique
Grand Poobah Joined: September-03-2005 Location: Big Rock, Il Status: Offline Points: 5772 |
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Mark, are you saying you have 9.7:1 CR now or after the head change? Your stock heads probably have 65CC Chambers and the AFR185 will have 58CC. If thats the case it's going to push your 9.7 CR to 10.5:1 which the aluminum heads will like better than iron. You're going to be in the same situation as me with those big valves and will need to check for piston to valve clearance before bolting everything up. Do you have more detail on the cam? What I really need to do this right is the following info from the cam card: intake valve open=_____ intake valve closed=_____ exhaust valve open=______ exhaust valve closed=_____ specify if the above is at seat to seat or .o50 timing. Advertised duration and/or .050 duration(just specify which it is.) Those numbers are as important as the lift for the program to work. If you don't have actual cam info I'll substitute data from a few known cams like mine or trbenj's. Later AA |
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You can’t change the wind but you can adjust your sails
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SNobsessed
Grand Poobah Joined: October-21-2007 Location: IA Status: Offline Points: 7102 |
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I know this will get a chuckle out out you speed freaks, but I am wondering if an upgrade to GT40P heads would give any fuel
efficiency gain at 2500-3000 RPM range. It looks like the torque went up a little, as opposed to stock. Is it correct to assume that is with same fuel usage? We run at this midrange 95% of the time & I have all the power I need. |
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“Beer is proof that God loves us and wants us to be happy.”
Ben Franklin |
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81nautique
Grand Poobah Joined: September-03-2005 Location: Big Rock, Il Status: Offline Points: 5772 |
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Mark,
I can run one based on assumed CR but we could get a better report if you have all the details on the pistons and cam. Later today I'll post all the detailed info required to do a proper test but in the meantime we'll use some assumed numbers. Crazy busy day today so if I don't get to you til tomorrow hang in there I didn't forget you. |
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You can’t change the wind but you can adjust your sails
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MaddMarxx
Platinum Member Joined: June-29-2006 Location: United States Status: Offline Points: 1741 |
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Alan..Do you think you could run that program on my motor with what i have now plus the upgrades I am going to add soon, I think the CR is close to 9.75 now, its has 30 over with flat tops, 1.7 rockers, block is decked with a wiend stelth intake, with stock heads now but i am going to add a set of alum AFR 185s, and a cam with around 470 lift and a holly 715 cfm and a set of edelbrock manifolds and alum under drive pullys with a fluid dampner, my Brother has been telling me the heads and cam could add 75 to 100HP, I would like to see if your program agrees...thank you.
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Gary S
Grand Poobah Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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Interesting thing to me is "the worlds fastest Mustang" my quotes,is that he's running basically stock exhausts with just some port matching.Maybe that accounts for why H&M's sound different.I would guess that the PCM's were not built for performance but for a way to get the exhaust out of the boat,fishing or skiing it didn't matter. Hiteks and to a lesser extent the H&M's I would guess,were made with performance 1st. I have to go now,I have to start locking my boat up
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Brktracer
Senior Member Joined: December-20-2007 Location: South Carolina Status: Offline Points: 387 |
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I just pulled a spare riser gasket from my tool box and it measures 1 1/4" X 3". That's only 3.75 in^2. Usually on a similar engine in a car we run a 3" collector - 7.065 in^2! It's fairly common to run a 2 1/2 exhaust system on similar engines which is 4.90 in^2.
The car that had an exhaust restriction I mentioned earlier picked up almost .5 sec in the 1/4 mile due to a 2 1/2" exhaust system with a pipe the installer shrunk to slip fit and weld together. No other changes except removing the restriction picked up almost .5 sec! Maybe we're on to something! Unfortunately, I don't have any flow data on the heads. Shoot me the report when you have a chance. brktracer@hotmail.com |
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81nautique
Grand Poobah Joined: September-03-2005 Location: Big Rock, Il Status: Offline Points: 5772 |
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Matt, Here's a graph based on your specs. Some of the input is guesswork but I think it's fairly close. Seems to match up pretty closely to a gt40 280 hp motor. Do you have flow data on the heads? Shoot me your email address and I'll send you a pdf of the report, if you want to change anything just let me know.
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You can’t change the wind but you can adjust your sails
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Brktracer
Senior Member Joined: December-20-2007 Location: South Carolina Status: Offline Points: 387 |
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Alan,
I'd be interested in borrowing your adapter when you're done. I have an Innovate LM-1 and Innovate LMA-2 for tuning my race car and would love to try it on the boat but never had a way to install it. I totally agree it would be interesting to cut the PCM manifolds and risers apart to see the inside. I chunked mine years ago when they were replaced. I was just thinking the other day that I'd love to have one back to cut open! The risers have a very small inlet and outlet. In fact, I'm betting the inlet is only about the same area as a couple exhaust ports. If I recall correctly the outlet is only about 2" diameter (inside). If the riser is the restriction that would be nice as it wouldn't be that difficult to fab a replacement. Anybody have an old manifold or riser for Alan or me to cut open? Maybe pictures of one cut open? Matt |
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81nautique
Grand Poobah Joined: September-03-2005 Location: Big Rock, Il Status: Offline Points: 5772 |
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Lastly I will be the first to admit that I am a rookie engine tuner, I've never felt experinced enough to interpret a plug chop confidently. Fully knowing my shortcomings there I am making an adapter that will sit between the manifold and the riser that will accept an air/fuel sensor. I've purchased an digital meter that will monitor A/F ratio at any rpm range and load so I can fully tune the engine in the spring. There's a good chance without it I will never get the engine tuned to perform near it's potential anyway. This will be a temporary meter so once dialed in it will be removed and I plan to make it available for anyone with PCM manifolds to borrow if they like.
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You can’t change the wind but you can adjust your sails
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81nautique
Grand Poobah Joined: September-03-2005 Location: Big Rock, Il Status: Offline Points: 5772 |
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Matt,
Several of us have had discussions about the PCM manifolds and the concensus is they may not be as constricting as they appear. Based on the results of those that have installed hiteks there seems to be a little disappointment to the performance improvements with that bolt on, not to say they're not worth it but the return may not have been as much as expected. With that said Reid seems adamant that the PCM risers are more of a problem than the manifolds themselves. I have a few ideas on that but need to do some more homework on alternatives first. Also if anyone replaces a set of PCM manifolds this winter because of rustout I would gladly pay to have them shipped to me so I could cut them open and get a cross section of them, I would expecially like to do that to a riser as well. |
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You can’t change the wind but you can adjust your sails
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