Hey Everyone, Long time no post.... Anyhow, I finally had an engine that I was involved with put on a dyno. The engine is not mine but a friends. I cant believe how nervous I was when the day came to put this on the dyno. I was almost as bad as when I had my first girlfriend:grin: The cylinder heads on this engine were the best I have ever ported and flow close to 360 at high lifts. It is 523 CID with a solid flat tappet camshaft. The intake manifold is a Chrysler B1 with the flanges machined off and replaced with Buick flanges. The oiling system is custom designed. The oil pan is a REALLY CUSTOM SRE and the pump that SRE supplies (Peterson). I have attached a picture of the dyno sheet. Guys and Gals... Watching an engine on the dyno is CRAZY scary. After the first two pulls I could not stand and watch it. I know.. I am a wuss!!! For those who have had an engine on the dyno, is there anything on this dyno sheet that looks crazy? Thanks
Yes there alot ZERO's on the page! :grin: Sure looks like its a very strong engine! Hope mine will have such good torque numbers when it goes on the Dyno! :TU:
For a guy who doesn't like to spin his motors, you've got that one making power at some pretty high rpm! The number my 523" made were at lower rpms than what you've got there....740 lbs ft of Tq, peaking at 5500 rpm and 840 HP, which peaked at 6500 rpm. Your's really SCREAMS! :eek2: Nice power though! :TU:
Gary, Having never had an engine on the dyno I really didn't know what to expect for Tq or HP numbers. I was please with the flat torque curve and the HP numbers. We dont race dynos so it will be interesting to see what the car will ET. Opa, I agree with the zeros on the page. I am sure information could be had from those columns with the 0s. The column that we most looked at is BSFC lb/Hphr. They were concerned with numbers below 35. Doug, I used to be concerned with RPM. That was years ago when we were running 9.50s. Then I realized to go fast you have to rpm the engine. When we run the car at wide open throttle we usually go through the traps at 7300 rpms. I dont know if this engine makes power up that high because of the intake or the camshaft or the intake/camshaft combo. I know I could have made the lobe seperation tighter on this cam but I think it would have lowered max hp rpm. I say again.. we dont race dynos so lets see how it runs in the car. Take Care,
Whos carb is on that Dale cubic? .The bsfc looks nice and flat no weird peaks. Very nice power for a flat tappet.
Very nice Numbers. I like the rpm! Is this the type of B1 that you used on the Buick? http://www.popularhotrodding.com/en...em_big_block_mopar_wedge_engine/photo_09.html
Kevin, Dale is the man!!! So to answer your question.. Yes it is one of his carbs. Dale actually worked his tail off to have the carb ready for this dyno session. Can you explain the BSFC to an old timer who just uses an EGT meter? Rick, That is the intake that was used on this engine. Take Care,
Here ya' go http://en.wikipedia.org/wiki/Brake_specific_fuel_consumption A lot of friends and myself runt EGT's on our boats due to the possibility of running wide open for several miles under full throttle. If you see the temp getting up too high, 1300-1500 degrees, you better back her down. This combined with a good oil temp gauge keeps things alive to get you back to the dock! ou: Coming back on a tow rope is not good, especially when the wife was giving you the slow it down stare earlier when you were driving like a maniac!!!
It is a tad lean i'd like to see .39 to .41.Thats where it may want to be on the dyno but in the car it will need to be richer.Being the curve is nice and flat that tells you that all the circuits in the carb are well balanced.If the #'s where all over the place you would have issues.I've have seen a few Cubic carbs on the dyno and the bsfc where all dead flat.Bob Book builds a good carb also his are the same way.
Hi John, Nice motor, highest HP flat tappet Buick I can recall.. The sheet below has the air, fuel and bsfc numbers on it, so you can see the corrilation. Your motor there is definately lean. JW
Ya John when michael did my/ now garys 525 it scared me too I was waiting for parts to come flying out of the thing. If you've never seen one dynoed its worth seeing.
OK... I did an internet search on BSFC and this is what I found... What do dynamometer BSFC #'s tell me? Brake Specific Fuel Consumption (or BSFC) is the ratio between the engine's fuel mass consumption and the crankshaft power it is producing. This makes it both a valuable fuel efficiency indicator and one more useful tool in gauging an engine's state-of-tune. In the USA, the fuel flow for BSFC calculations is normally expressed in pounds per hour (lb/hr) while the output units, of course, are in horsepower (Hp). So, our standard formula for BSFC becomes: lb/Hp-hr . For an engine producing 200 horsepower, while guzzling 100 pounds of gasoline per hour, the equation would yield 100/200 = 0.50 BSFC. Unlike AFR (Air/Fuel ratio) readings which only reveal the mixture, BSFC data represents the power provided per fuel unit. AFR and BSFC are not equivalent! The beauty of BSFC #'s are that they remain similar over a wide range of engine sizes (assuming both are of similar mechanical design and compression ratio). For example, a tiny one cylinder 50cc four-stroke and a 454ci V8 might both have a BSFC ratio of 0.45 lb/Hp-hr (when optimally tuned) at their respective peak torque points. Thus, if either of these engine's were overly richened, its BSFC might climb into the 0.55 to 0.65 range (because the fuel flow in our equation will be going up as the power is going down. Consider the above example on a dyno that only displays horsepower. Without the BSFC data, it is harder to know that a rich mixture engine is the reason for sub-par output. But, when you also have the BSFC numbers in front of you, it aims you at the cause. BSFC values all follow a hooked curve. At idle they run much higher - due primarily to the closed throttle pumping losses and excessive camshaft overlap. Minimum BSFC #'s occur at about the peak torque operating rage - the most fuel efficient (per Hp) operating point for an engine. As RPM increases towards peak power, the BSFC rises again, since more fuel energy is consumed just overcoming the speed induced friction and breathing restrictions. Below are sample BSFC ranges for several typical engine types. Note, these are provided to illustrate relative BSFC behavior only. Realize that any change that improves the mechanical efficiency of the engine (e.g. a dry sump oil pan, electric water pump, low tension rings, lighter oil, etc.) will also reduce its BSFC values! -------------------------------------------------------------------------------- Engine @ 1,000 @ Peak @ Peak Type RPM Torque Hp 4-stroke (low compression, carburetor) 0.62 0.47 0.52 4-stroke (high compression, carburetor) 0.60 0.42 0.47 4-stroke (high compression, closed loop) 0.52 0.35 0.42 4-stroke (supercharged, carburetor) 0.75 0.50 0.55 4-stroke (turbocharged, closed loop) 0.57 0.45 0.50 2-stroke (low compression, carburetor) 0.85 0.55 0.60 2-stroke (high compression, carburetor) 0.80 0.50 0.55 Diesel 4-stroke 0.35 0.25 0.30 Diesel 2-stroke 0.40 0.29 0.34 To find the optimum fuel curve for an engine running on the dyno, you should experiment with richer and leaner air fuel mixtures at incremental steady state test points (e.g. every 250 RPM). Starting with a known safe AFR value (rich fuel map, jet, or mixture needle setting) record the Hp, temperature, and BSFC values. Lean down slightly and retest – you are looking for improved power. Keep in mind that you can easily go too far and end up sticking a piston, etc. This is why you must listen for knocking while monitoring the EGTs, AFR, and BSFC values. Experienced tuners will push the envelope a bit to get a flash Hp reading – but then back off for a cooling period - before the thermal heat sink protection is lost. Once the peak safe power mixture is determined for each RPM point you can plot a target BSFC curve for the engine combination. Actually duplicating that shape is easy with a mapped fuel injection system. For carburetor equipped applications you normally need to work out air emulsion tube air bleed sizes, tweak boost venturis, etc. and even then some compromises must be accepted. Back on the road, dynamometer optimized curves often prove to be a bit too lean for a good driving feel. This is because during transient conditions, like moving the throttle or accelerating, mixture requirements change. Since a slightly richer mixture only depresses power a tiny amount, whereas a slightly lean mixture can cause a very noticeable miss-fire and bog, the best drivability compromise is usually to richen up a tiny bit. That way, objectionable lean bogs are avoided at only a small expense of power and fuel economy. The overall dynamometer verified fuel curve is still valid; it’s just been made more tolerant with a little fattening. As you gain tuning experience with various engine and induction system combinations, you will be able to hit an acceptable derivability mixture with little or no road test time. Compare that with blindly flogging the engine to death on the track – trying to optimize the best power curve mixture.
After reading what I had posted in the last post, I would agree that the engine was running a bit lean. But the EGT meter that we had set up showed and EGT in the 1270s which would show a slightly rich condition. When the BSFC was .34 or lower the plug was a bit to white. The plug at .35 to .36 the color was OK. Things that make you go Hmmmmm.
Remember John what one motor likes may be different then another.Fuel brand also comes into play.Our ford motor liked the plugs to be white with a very slight fuel ring at the bottom of the insulator if we tried to put fuel into it we lost power overall (vp nos).We tuned it until we made the best overall power on the dyno not peak.We also looked for a nice flat bsfc.You can find other problems with bsfc. If you have a very unstable curve you may have a valvetrain stability issue choke point in the intake tract or exhaust.In 2007 when we were chasing the nsca Limited street points we were on the dyno 5 different times 100 plus pulls trying different cams valve springs and carbs in order to make our combo work.At the end of the season we found 38 average hp.We had a valve train issue early in the season that plagued us until the 2nd to last race.You could feel it or hear it but the bsfc was all over the place if I can find the dyno sheets I'll post them to show what was going on. All in all looking at what you have there is a very good motor fire it in the car and rip it lets hear what it does.
Disclaimer...from what I've read.... EGT's can fool you, think of it as a sloped curve, it gets slippery as you go more lean. You can have a cooler EGT due to: - Being too rich, more un-burned fuel to cool the exhaust runner - Being too lean due to less fuel to make heat A slight rich from optimum HP is where you want to be, it's more safe than slight lean. If you are running for top speed, good insurance is to go more rich, maybe 12.5 or so. Often times EGT readings are taken from only one or two cylinders or from only one side of the engine. You need to leave a safety factor for other more lean cylinder(s). My BSFC was .38 at peak torque with a AFR at 12.48. I've heard with engines with higher HP/Cu-in ratios like 1.5 (mine was only 1.14), a higher AFR can work like 13:1 or more. This is all cool, but the moral of the story is to tune for mph. Great numbers John, and good research!
I read an interesting article relating to airplane engine tuning yesterday. It discusses the advantages of altering AFR's for various situations. This "tuning on the fly" is cool; cruising with a lean mixture (for better ecomomy, light load) and using a full rich mixture for heavy load (take off). Here's a graph showing general trends for EGT, BSFC and % power. This kind of thing could really help when making changes on your combination.
