|
SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Wiseco CR - The Facts /cgi-bin/YaBB.pl?num=1588580303 Message started by DragBikeMike on 05/04/20 at 01:18:23 |
|
Title: Wiseco CR - The Facts Post by DragBikeMike on 05/04/20 at 01:18:23 One of the performance options available to a Savage owner is the Wiseco High Compression forged piston. I have seen some advertisements for the Wiseco that state a compression ratio (CR) of 10.5:1. The stock engine has an advertised CR of 8.5:1. So the Wiseco is supposed to increase compression by two points. Given the Wiseco’s modest .060” pop-top, a two-point increase seems a little optimistic. I decided to take a good look at the Wiseco to figure out exactly what the real compression ratio is. I opted to use the on-line calculator at RB Racing. It has inputs for the deck height along with the valve reliefs. All I would have to manually calculate was the volume of the pop-top. Here is a link to the RB calculator. It is a good tool, save it. They also have a bunch of other calculators on their site. https://www.rbracing-rsr.com/compstaticcalc.html |
|
Title: Re: Wiseco CR - The Facts Post by DragBikeMike on 05/04/20 at 01:19:52 I started with the stock CR. I wanted to see exactly where we are starting from. I measured the combustion chamber volume on my box-stock head. It is from a 2016 LS650. This is the third LS head I have measured. All three were around 56cc. Lay a piece of clear plastic on the head. Seal the periphery around the combustion chamber with grease. There must be a hole in the plastic to allow filling the combustion chamber with oil, and the head positioned at an angle so that the hole is at the highest point. Fill it up with oil from a graduated burette. Here is the head ready to fill. |
|
Title: Re: Wiseco CR - The Facts Post by DragBikeMike on 05/04/20 at 01:20:33 The burette. I'm just using the hole in the cylinder to stow the burette while I'm getting ready to fill the combustion chamber. |
|
Title: Re: Wiseco CR - The Facts Post by DragBikeMike on 05/04/20 at 01:22:44 The oil level in the burette started at the 30 cc mark and once the combustion chamber was full the oil level was at the 86 cc mark, so the chamber took 56 cc to fill. |
|
Title: Re: Wiseco CR - The Facts Post by DragBikeMike on 05/04/20 at 01:23:39 Here is what a full combustion chamber looks like. There is just a tiny bit of trapped air. Not enough to be concerned about for this drill. |
|
Title: Re: Wiseco CR - The Facts Post by DragBikeMike on 05/04/20 at 01:24:17 So now we know the combustion chamber has a volume of 56cc. Next, we need to know what the deck height is. I have previously measured the deck height on both the stock piston and the Wiseco. Deck height is the distance from the head gasket surface to the top of the piston (when the piston is at top dead center). The deck height with the stock piston is exactly .162”. |
|
Title: Re: Wiseco CR - The Facts Post by DragBikeMike on 05/04/20 at 01:24:59 Next, we need to know the head gasket compressed thickness. I have previously measured the stock head gasket thickness. It's .028” fully compressed. |
|
Title: Re: Wiseco CR - The Facts Post by DragBikeMike on 05/04/20 at 01:26:27 We need the bore diameter. For a stock engine, the bore diameter is 94 mm (3.701”). I add .002” for clearance and end up wit 3.703”. We need to know the stroke. The LS650 has a stroke of 94 mm (3.701”). We also need to know the piston top volume. That would be the volume of any dish or valve reliefs. The stock LS piston has no dish or valve reliefs, so the piston top volume is zero. Plug in the following numbers and run the calculator. Bore: 3.703” Stroke: 3.701” Head Gasket: .028” Deck Height: .162” Piston top volume: 0 Combustion Chamber: 56 cc Using the actual no-bull numbers, you get a CR of 8.3:1. That is a bit shy of the advertised 8.5:1, but hey, it’s pretty close. Suzuki fudged a couple of tenths. |
|
Title: Re: Wiseco CR - The Facts Post by DragBikeMike on 05/04/20 at 01:27:08 Now let’s look at the Wiseco. The pop-top is not a full circle. It’s .060” tall and it has a couple of circular segments lobbed off. There are a couple of valve reliefs too. A little more complicated. |
|
Title: Re: Wiseco CR - The Facts Post by DragBikeMike on 05/04/20 at 01:28:00 Start by taking some dimensions on the pop-top and calculate the volume. I won’t go into all the gory details. I will just attach a picture of my measurements and calculations. The result is about 6.5 cc. |
|
Title: Re: Wiseco CR - The Facts Post by DragBikeMike on 05/04/20 at 01:28:47 We need to figure out the volume of the valve reliefs. I decided to see if I could use plumber’s putty. |
|
Title: Re: Wiseco CR - The Facts Post by DragBikeMike on 05/04/20 at 01:29:30 The putty must be heavier than oil so that it will fully displace oil in a graduated beaker. If I drop a cubic centimeter of putty into a beaker full of oil, the oil level should rise exactly one graduation (1 cc). First, test to see that the putty will work. It sinks, good to go. |
|
Title: Re: Wiseco CR - The Facts Post by DragBikeMike on 05/04/20 at 01:30:11 Now, fill each valve relief with plumber’s putty and neatly slice off so that the putty is the same volume as the valve relief. A little oil on the scale works great. |
|
Title: Re: Wiseco CR - The Facts Post by DragBikeMike on 05/04/20 at 01:30:48 You end up with this. |
|
Title: Re: Wiseco CR - The Facts Post by DragBikeMike on 05/04/20 at 01:31:32 Now carefully scoop out the putty from each valve relief. I use a little brass spatula. |
|
Title: Re: Wiseco CR - The Facts Post by DragBikeMike on 05/04/20 at 01:32:11 Then drop the putty into a graduated beaker filled to a known level with oil. When I dropped the two pieces of putty into my beaker the oil level rose about 1 cc. So, each valve relief has a volume of 0.5 cc for a total of 1 cc. |
|
Title: Re: Wiseco CR - The Facts Post by DragBikeMike on 05/04/20 at 01:33:36 The volume of the pop-top sticks up and reduces the volume of the combustion area, while the volumes of the valve reliefs increase the volume of the combustion area. One offsets the other. So, adjust the volume of the pop-top by 1 cc. The pop-top volume of 6.5 cc minus the valve relief volume of 1 cc leaves 5.5 cc. The high compression piston should reduce the combustion area by 5.5 cc. We could use negative 5.5 cc in the calculator for piston top volume, but I wanted to make sure. I wanted to cross check my calculations, so I set up the 97 mm Wiseco exactly .095” from the top of the cylinder. That .095” is measured from the flat top surface (red check), NOT the top of the dome (red X). |
|
Title: Re: Wiseco CR - The Facts Post by DragBikeMike on 05/04/20 at 01:34:34 The volume of the cylinder above the flat top is easy to calculate. The bore is 3.819” and the height of the area is .095”. Pi x the radius squared x height = volume. That works out to 1.088 cubic inches (17.829 cc). Subtract the piston top volume of 5.5 cc and we should have a final volume of about 12.3 cc. So, with the piston locked in place at .095” below the top of the cylinder, I sealed all around the top with grease. Then I installed the clear plastic and filled the area with oil. |
|
Title: Re: Wiseco CR - The Facts Post by DragBikeMike on 05/04/20 at 01:35:28 It took 11.5 cc of oil to fill the area. That indicates that the piston top volume is 6.3 cc (17.8-11.5=6.3). I opt to use the 6.3 cc value. Since it reduces the volume of the combustion area it must be expressed as a negative value. |
|
Title: Re: Wiseco CR - The Facts Post by DragBikeMike on 05/04/20 at 01:40:33 We are now ready to use the calculator. The pop-top for the 94 mm Wiseco is identical to the pop-top for the 97 mm Wiseco, so we can use the same piston top volume (negative 6.3 cc) for either piston. Use the following values in the RB calculator: Bore: 3.703” for 94 mm, 3.819” for 97 mm Stroke: 3.701” Head Gasket: .028” Deck Height: .143” (Wiseco is a bit taller than stock) Piston top volume: -6.3 cc Combustion Chamber: 56 cc With the Wiseco 94 mm piston you end up with a compression ratio of 9.2:1 With the Wiseco 97 mm piston you end up with a compression ratio of 9.5:1 These values fall well short of 10.5:1, but keep in mind that the Wiseco we are using was intended for the DR650. I assume that the DR engine brings the piston much closer to the top of the cylinder, which in turn results in less negative deck and a higher static compression ratio. I am currently running a 94 mm Wiseco. The cranking pressure is about 30 to 40 psi higher than stock, and it runs a lot better than it did with the stock CR. Now I have a better idea where I stand and what I must do to bring the CR up to an honest 10:1. I hope this report serves as a useful reference. Knowledge is power. Mike |
|
Title: Re: Wiseco CR - The Facts Post by Gary_in_NJ on 05/04/20 at 05:39:11 Excellent work Mike. |
|
Title: Re: Wiseco CR - The Facts Post by batman on 05/04/20 at 06:40:03 DMB, If you're still using the head where you modified the intake passage ,you may have a higher compression due to higher VE, maybe somewhere between 9.5 to 10:1, how much compression are you really willing to try considering that you said your oil temp had been running 340F. While on that subject , rather than running 20w50 , I would think that you might try Rotella 5w40 instead, decreased pressure = increased flow which carries away more heat and the SAE Conference stated that if you can decrease oil temp by 20 degrees in a motor that the oil would act as the next higher grade (50w) . It seems worth investigation . |
|
Title: Re: Wiseco CR - The Facts Post by justin_o_guy2 on 05/04/20 at 06:56:02 Here NOW!,, Not everyone following this knows the cool abbreviations,, VE? Just figuring out HOW to establish the volume of places is cool.. Of Course it makes perfect sense,, fill it with putty,, remove the putty, measure the isplacement of the putty,, Violas,, Volume is discovered! Dang nifty lab toys Mike,, |
|
Title: Re: Wiseco CR - The Facts Post by Armen on 05/04/20 at 07:07:05 Once again, well researched and documented! I've always just assembled the top end with a bit of grease around the top ring land and filled oil in thru the spark plug hole til it hit the bottom of the plug threads. I get it that with an engine in the frame, this is often impossible. Any reason not to do it that way with the Savage? Were you really seeing 340F oil temps?!?! thanks |
|
Title: Re: Wiseco CR - The Facts Post by Fast 650 on 05/04/20 at 10:46:32 3C2325223F3809390931232F64560 wrote:
VE=Volumetric Efficiency. Just because you have 652cc of space to fill does not mean that you filled that space to full capacity. 100% VE would mean that you have 652cc of fuel/air mix in that cylinder. At higher RPM there isn't enough time for the intake charge to completely fill the cylinder before the valve closes, and VE starts going down at that point. That is why you see torque and horsepower climb then begin to drop past a certain RPM on a dyno graph. |
|
Title: Re: Wiseco CR - The Facts Post by Armen on 05/04/20 at 11:28:59 Actually, Fast, on a well tuned motor the intake doesn't close til ABDC and the incoming charge continues to some in. You can actually get more than 650ccs of mix into a 650cc motor. |
|
Title: Re: Wiseco CR - The Facts Post by Fast 650 on 05/04/20 at 17:53:39 I know, but it is easier for the average person to visualize a drop in efficiency than to understand how you can get more than 100 percent efficiency. They start thinking that you are selling high grade bovine fertilizer then. :) |
|
Title: Re: Wiseco CR - The Facts Post by DragBikeMike on 05/04/20 at 19:48:26 Batman, that's a good point regarding dynamic compression ratio. The RB Racing website also has a calculator for that. You need connecting rod length (6.573") and intake valve closing point (depends on cam). I haven't had much success with that particular calculator. Wallace Racing also has one. I get different values depending on which calculator I use. This particular exercise is geared toward gathering the data needed to determine static CR. Based on my personal experience with the LS650, I'm gonna shoot for 10:1 static CR for my next project. BTW, that 340F was cylinder head temp not oil temp. I'm fiddling around with some ideas for an oil cooler so I'm planning on doing some testing on the two oils (10W-40 & 20W-50) to get some baseline data. Versy's report of 50 psi at the crankcase port threw a monkey wrench in my plan so I'm back to the drawing board. I think I have some good ideas. Just need to turn them into hardware. Hey Armen, I've used your technique a time or two. It's kinda messy when it's time to get the oil out, but it certainly gives you a good number. One of those fancy engine stands like you have would come in handy for that. Measuring the different volumes gives more flexibility but also can introduce errors. Now I know the volume of each key part in the mix. I have more choices when it's time to adjust the squeeze. I can also figure out the weight of the pop-top so I can get a feel for how much it will affect vibration if I lob the top off to make a tight-quench setup. It's all good. 8-) |
|
Title: Re: Wiseco CR - The Facts Post by Armen on 05/05/20 at 05:47:35 Hey Mike, Maybe I'm being slow to think, but it seems like a lot of work. With the new piston, if you measure down from the top of the cylinder to the edge of the squish band (is that the .143" measurement you have?), and figure that into the basic volume of a cylinder formula and call that "X", then put on the plate and fill with oil and call that "Y", can't you just subtract Y from X and have the change in volume caused by the difference in dome shape? It's just that I'm way too lazy to do the math. Even if you had a pop top that stuck above the surface of the cylinder, you could drop the piston down a set amount (say 10mm) and do those measurements. |
|
Title: Re: Wiseco CR - The Facts Post by justin_o_guy2 on 05/05/20 at 06:19:14 Thsanks both of you,, and yeah,, the General explanation first probably was better. I do understand a column of air moving, too,, but IM glad we didnt start there |
|
Title: Re: Wiseco CR - The Facts Post by LANCER on 05/05/20 at 14:14:48 Easy to follow & good info. Thanks |
|
Title: Re: Wiseco CR - The Facts Post by DragBikeMike on 05/05/20 at 14:42:29 Armen, that is exactly what I did. I calculated the volume of a cylinder 3.819" diameter, .095" tall. Then I compared that to the measured volume of oil. That measured volume included one additional cc of valve relief volume. Then I compared one value to another. The geometric calculation of the pop-top was 6.5 cc while the direct oil measurement showed 7.3 cc. It was an 0.8 cc difference. Since the pop-top has beveled edges I felt that the geometric calculation was less accurate so I used the direct measurement with oil. Subtract the volume of the reliefs (1 cc) and you end up with 6.3 cc. |
|
Title: Re: Wiseco CR - The Facts Post by srinath on 05/06/20 at 16:22:51 082F3D3A787B7E4E0 wrote:
Long intakes with a long column of air moving at a good steady velocity accomplishes this rather well. Moving the carbs away works better than making them bigger for this aspect in many cases. Cool. Srinath. |
|
SuzukiSavage.com » Powered by YaBB 2.2! YaBB © 2000-2007. All Rights Reserved. |