Those are excellent results and congrats. It goes to show how improving your compression ratio can do good things.
My results are lower likely due to my compression ratio being stock, with stock cam and older rings.
What I do notice is your 4150 doesn't seem to be dialed in. 11 to 12/1 air/fuel ratio is generally seen to be ideal and your bottom end looks fat and your top end lean. I also see alot of unevenness in fuel the metering. I don't know why that is. Maybe your mechanical secondaries need setting up.
Below is my last dyno (before I changed the shooter). The dyno sheet is actually not accurate because the software was not adjusted for my final drive ratio. (.81 in 4th and 1.24 in 3rd). But, as you can see on my air/fuel ratio, I was too fat on the bottom and probably a little too lean at my top end. The shooter remained fat (with a horrible bog) until I put in a #21 shooter with the white cam.
Mine seemed to even out with less shooter and #512 jets on the primary with #52's on the secondaries. Your engine is making more power than mine so a #25 shooter may be more correct. What are your jets and shooter?
I am headed back to the dyno next week with some changes that should even out my carb setup and hopefully pick up the engine's response. Hopefully I'll get a more accurate hp reading so we can compare better.
Arn
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09:27 AM
Oreif Member
Posts: 16460 From: Schaumburg, IL Registered: Jan 2000
So is that driveline loss calculated into the graph? if so, I get 150.6 rwhp... Generally speaking it's ~25 hp loss so you are probably closer to 148 rwhp, still very impressive.
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10:11 AM
joeformula88 Member
Posts: 114 From: arnhem, the Netherlands Registered: Mar 2000
We only changed jets in the primary and secondary side. Shooters and cams are up next and were unchanged for these runs (still standard). I now have 54 in the primary and 42 in the secondary. I have continuous monitoring of the A/F ratio>hooked up a LEDdisplay to the O2 sensor. Under normal driving and steady load it's not rich, meaning primary jetting is about where it should be. Secondary was brought down to 42 to get from the red curve (initial) to the blue one (closer to ideal under full load) When you floor it, the engine responds better if you then slowly lift a bit. Anyone knows what that means in terms of acc.pump/shooter/secondarys, or is this a typical (holley?) carb thing?
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10:18 AM
Alex4mula Member
Posts: 7410 From: Canton, MI US Registered: Dec 1999
When you floor it, the accellerator pump is the first item to give you gas. The size and duration of the shot of gas is determined by the nozzle (shooter) and the duration by the cam. For instance a 17cc cam setting will run out of fuel before a 19cc cam setting. For most applications even up to V8's the stock 30cc diaphram works well.
If it is too rich the engine will start to jump and then bog when you first punch it and then it will recover. If you don't get an initial bog your shooter is generally ok. If it is too lean a shooter it will hesitate when you hit it. The stock shooter on mine was #25 with the white cam. I experimented with the orange cam (19cc position) and ended up with #21 shooter with white cam (17cc). You can see on my chart that the shooter was really affecting the engine for about 800 - 1000 rpm from start. Then things even out. Notice you can tell my secondaries come in around 3200 rpm.
You'rs looks like either you have a really long shot (more cam in it) or your primaries are just a little too fat. It also looks like your secondaries are coming in maybe 4250 rpm. The chart says to me that you need less primary jetting and maybe a tiny bit more secondary jetting plus earlier secondary actuation. Maybe have the secondaries coming on at 3500 rpm as a start. I'd try going down to a #52 primary. I'll bet your numbers will show the difference and you may make some gains you're looking for.
BTW, you now have me thinking I maybe should have upped my compression
Arn
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12:07 PM
ryan.hess Member
Posts: 20784 From: Orlando, FL Registered: Dec 2002
Arn, Thanks for all your advice, I will do some more experimenting with my jets and acc. pump settings as you suggested. I have also noticed quite a large influence in the four-corner idle mixture adjustment. if you make it richer it will also enrichen the mixture in above idle conditions! I need to figure out it's influence more precisely. Momentarily it's a bit rich when idling. Arn, I believe the cam probably did more than the compr.ratio? Also will I take Oreif's advice on going from 2 to 2.5 inch diameter on the exhaust pipe and change the stock mufler to a performance mufler. Cat is already out the window of course. Fie Ro: I'l be there for sure. I will also invite Mark from Hedel (fierofanaticfromholland), if he's not already aware. Thanks for inviting!
I set the idle with a vacuum guage. You unhook usually the PCV and plug in the vacuum guage to it. When you turn the idle screw in far enough the engine will begin to stumble. Back it out until it recovers and then about 1/4 turn and you should be there. Edit - you're looking for max vacuum and max idle speed.
I'm running the 4160 so my secondary side has no idle circuit.
Oreif is correct about the 2.5" pipe. There is something else. The headers used for S10 applications on the 2.8/3.1/3.4 are 1.5" pipe right from the flanges for 30" before collecting into a 3" pipe. If you have the facilities to make custom headers you might gain quite a bit. I've read a 3.4 can gain up to 17 hp with that change. I would do it, except I don't yet have the skills to do it myself and I don't have the coin to pay somebody.
I'll post what I get next week at the dyno so we can compare. BTW mine is measured at the wheels.
Arn
[This message has been edited by Arns85GT (edited 07-20-2006).]
