AFR 205's make big power
I went to ECS and did my final PE and timing tweaks but didn't have enough time to finish and thoroughly tweak the AFR and timing for peak torque and hp. However, I'm fairly close with about 10/10 on the table, maybe a scouche more?
I have to thank Doug, (Thanks Doug!
) for pulling an alternator out of his back pocket when I killed mine on the dyno.
And also to Mike for popping the old one out and the new one in so fast I didn't even know it was done! Tony Mamo came through again. Thanks again Tony.
Below are the numbers and the specs are in my sig. This is with a stock water pump, 4:10's, and Kooks cats (Magnaflows - I think). The car drives around town like stock, but runs like a 'scalded dog' or a 'raped ape' or whatever when I push the long thin pedal on the right side.
The AFR is very flat at 13.1:1 from the onset to the rev limit, hence the lower than optimum tq/hp levels.
Congrats on your results. Scalded dog comment is too funny.
Regarding a DynoJet and a DynaPack dyno, trust me the read very similar UNLESS you run heavy aftermarket rims and tires. With a Dynapack that variable is eliminated as the dyno bolts directly to the wheel hubs. With my reasonably light 10.5" Z06 rims and lighter Nitto DR's (tire/rim combo around 48 lbs) the two dyno's were virtually identical, but I have seen some combo's dyno 10 or so RWHP more on a Dynapack that ran heavy rim/tires combinations (which would cost you power on a DynoJet or any typical wheel dyno)....some of them over 60lbs each. Also, for anyone questioning these results, look at the torque which is what this dyno is actually measuring (like a flywheel dyno would)....its not unusually high at all for this combination. The key to the big power is that the optimized set-up related to its airflow and breathing ability allowed that torque curve to hang on much longer at higher RPM and thats how the big power came to be....purely a mathmatical function of the torque produced and the RPM turned. When you see a 346 make 400 RWTQ at 3000 RPM's and see an abnormally high power curve then you start to question things as it would border on impossible for an engine of that displacement to produce that much torque at that RPM.
Congrats Roger....it was a long time coming but worth the wait.
BTW, the best part about this combo is the insane throttle response, tip in power, and overall SOTP from the small heads. The car feels even faster than than the stout numbers you guys see at WOT because the part throttle of this combo would "feel" like a much larger engine was actually installed.
Good stuff....
Regards,
Tony
Last edited by Tony Mamo @ AFR; Jul 11, 2008 at 02:23 PM.
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Not questioning your judgement, more so just looking to learn a bit and understand why you went the direction you did, and the results of that decision.
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Not questioning your judgement, more so just looking to learn a bit and understand why you went the direction you did, and the results of that decision.
The specs on the motor and combo are as follows:
LPE 403 - forged with a Dragonslayer crank, Compstar Rods, and Mahle pistons. - tried to keep it lightweight. stock LS2 waterpump, LS2 timing chain and gear. Comp XER Grind 242/242 .610"/.610" 114LSA installed +2. Cadillac racing lifters, 7.375" Comp pushrods, Yella Terra UL rockers, installed with .080 shims (best wipe). .030" Cometic gaskets (slugs were .010" in) LPE high volume oil pump.
AFR heads worked by Tony Mamo, AFR 8019 springs shimmed. BTW, these heads were beat up from my previous build. One chamber was toast with the washer that fell in still in the head. So he had to reweld them and resurface them. I couldn't see where the damage was after I got them back. I could only detect a slight discoloration where the welds went in. This also brings me to the reason for going with 205's. I had them and didn't have to invest in a new set. Also, for less than the cost of buying a new set of 225's I got a great chamber rework and porting job from one of the best. Also I discussed with Tony the benefits of the 205's vs. the 225's, and what I wanted the car for. Since it isn't a drag car and I was planning on using it for fun and some HPDE's we agree'd that having nasty throttle response coming out of a corner or spanking some rice stoplight to stoplight was more important than absolute top end performance. Tony nailed it with these heads and cam combo.
VaraRam B2 - VaraRams typically make a little less power sitting still on the dyno as they are designed for pushing air, not pulling it. - This is also debateable.
Haltech Airbridge modified to mate between the VaraRam and a PowerMax 100mm MAF (uses the new Hitachi MAF element).
Nick Williams 90mm TB - I'm thinking of having Tony port this too. Problem is, he's so damned busy! Tony Mamo ported 90 mm FAST.
Kooks 1 7/8" into 3" xPipe with cats to 3" mid-section to Z06 Ti's.
The clutch and PP are a Textraila OZ700 and billet steel flywheel.
The rear is a built 4:10 from ECS.
So the power was made through cats, TI's, stock water pump, and 4:10's.
And as far as throttle response goes Tony is right, it's instantaneous. I cannot stab the throttle in 1st or 2nd or I hit the rev limiter almost instantly.
MY daughter works for Lamborgini and has been in the new LP560 a bit. When I took her out in my car she had to admit it was faster. Made me feel really good, since she's become a bit of an elitist
Not questioning your judgement, more so just looking to learn a bit and understand why you went the direction you did, and the results of that decision.
I went very heavily on Tony's recommendation. I believe that velocity is more important than volume when building NA power. So we talked about matching the heads with the cam. Also, Tony opened up the chambers for the 4" bore which also unshrouded the valves a bit. I've read you can use about 10 degrees more duration on a 402 than with a 347 so the cam really isn't that big. Also we went with a 114 LSA to keep the overlap down for a wider torque curve, again adds to the throttle response.
What I suggest to anybody contemplating building a new combo is to really be honest about what you want the car to do. Making big numbers is easy to do, but it costs a lot of money and why spend it twice? When I was forced into redoing my motor my head was spinning with possibilities. I had been doing a lot of research on these boards and learned a lot, but I've learned that a little knowledge can be dangerous. Also, you can't replace experience, so I contacted the guy I thought would be the best to redo my heads, Tony, since he designed them. I then learned he's been building motors for a long time and has thousands of hrs working on LS1's, etc. So I started asking questions and soon realised I was talking to an experienced engine builder. The outcome was a car that is pretty snotty for a budget build, it's reliable, and drives like stock around town, with no surge, etc. I can take my wife out to dinner in it, have a converstion with her while listening to the radio, and give the keys to the valet and he can drive it and park it. Then on the weekend I can put the CCW's on it and take it to the track and have a good showing.
How big are your combustion chambers bro ?? Mine were milled to 59cc.
What size valves you got in those heads ?? What compression are you running ??
I think the 3.42's will show ~12-15 more hp/tq than the 4:10's. Best of luck on meeting your goals.







