The Velocity Myth

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funmachines · #31 Post by **funmachines** » Thu Jun 14, 2007 2:42 pm

Does anyone have flow bench numbers and port volumes for stock and ported heads? It would be interesting to compare to other high performance heads out there.

I have a set of v8 race heads ready for flow bench testing right now and I was thinking about taking a stock Dale head down to get it flowed at the same time (unless someone already has data).

timbomoose · #32 Post by **timbomoose** » Sat Jun 16, 2007 3:57 pm

I'm glad you brought up the point about flowrate. Many people think that that's the exact # you go with and all is done. Not the case. Fuel pressure varies from machine to machine and also flow from the injectors. One example is I dynoed to 2 idententical 467's same day same dyno same pipes same airboxsetup porting ,etc. One ended up being a 2220 flowrate and the other 2050 flowrate and both were a 1.1 offset. Both motors had identical hp and tq curves within less than .3 hp difference. The afr's were almost identical with the same maps but with way different flowrates. I've also had motors that size ending up in in the upper 2300's with same hp tq results. I once had a ported 432 that ended up with a 1700 flowrate which is not normal. It ended up being a very week regulator and changed it and was within the normal ranges.This just shows how important it is to tune your motor and parameters supplied are just that, starting parameters. Different pipes,airbox setups,cam timings,porting,etc all affect the afr, sometimes drastically. The only way to get the true potential out of your motor is by doing some tuning. A D&M is a must when doing mods or might be really missing the boat on power. There is nothing wrong with different porting just different. Different porting will affect where the power hits where it falls off and where and how much fuel you need in the rpm range. The big importance is that the gains are made and where you can use it. Got some 50hp,55hp,60hp club stickers waiting for 2000ex. Eat up all other brands.

timbomoose · #33 Post by **timbomoose** » Sat Jun 16, 2007 4:10 pm

Another good thing 2000ex brought up is deceleration backfiring. Thats a sign of 2 things lean condition or leak in the exhaust. The maps I make are set lean in the lowend almost a point leaner on the afr. This makes it a little easier to tune. Got some backfiring going on, more gas to the map. A couple weeks ago I had some heavy backfiring going on on mine during deceleration and also no bottom end power and was just not running as strong. After I got home I unloaded it of the truck and heard the difference in sound(helmet off). Looked at the exhuast and the headpipe on one tube was cracked broken off and not connected anymore about 3 inches from the head. Ouch had to be my ti pipe. At least I found the cause.

2000ex · #34 Post by **2000ex** » Sat Jun 16, 2007 7:04 pm

Tim,

What is the difference between the terminator and the trinium map?

timbomoose · #35 Post by **timbomoose** » Sat Jun 16, 2007 8:53 pm

Grams of fuel in the map is the major difference. The trinium map came about from someone who dyno tuned the motor in wot and had problems in the low end running right. I tuned the low end in the map for the customer on with the quad and resent to him not changing his flowrate or offset and said it ran 100% better. The big difference is that the trinium is set to run in parameters around 1600-1900 flowrate and the terminator is set to run between parameters 2075-2375. The trinium must be set much richer on the flowrate.I have never seen the trinium on the dyno so could not tell how how rich or lean in all areas of the map everything is.Everything on the map accept for the top line was made by feel while riding,but again which map that would work best would depend upon porting,pipe,cam timing etc. Don't be afraid to try different maps and play with fuel settings. Every different ported head & pipe combo like its own map or different fuel settings. Only thing to stay away from is high rev limiters on a stroker crank,because of piston speed.I recommend a 10800 rev limiter and no higher than 11000.With the bigger stroke you are able to gear it much higher and pull harder. You'll never miss the extra rpms. I've been running 15-40 with 20"rears on my 467 and love that gearing for trail riding. It's just alittle tall in the really tight stuff but the stroker lets you lug the motor alot lower without stalling and very little shifting is required.