Patrick G

iTrader: (14)

Interesting gains on the flow bench and on the dyno. On the flow bench with a 3.900 bore, the AFR 225 small bore heads were identical in flow to the 205s from .100"-.400" lift.

Gains of the 225s over the 205s at higher lifts:
At .450" +11
At .500" +15
At .550" +23
At .600" +21
At .650" +31

Because I run a .650" lift cam, we felt my car would be a good candidate to take advantage of the killer increase in flow at higher lifts.

Here's the kicker though. My car has a razor sharp speed density tune I spent literally MONTHS perfecting. Now, I was bolting up a better flow set of heads and I couldn't rely on a MAF to compensate for the extra airflow.

For a baseline program, we added 5% to the VE tables at 90, 100kPa (figuring a 5% flow increase and power increase). When we hit the dyno, we were WAY lean. When it was all said and done, we wound up needing to add over 15% fuel to the top end numbers. The motor was flowing more air and definitely wanting lots more fuel. Surprisingly, we only got 5 rwhp gain and 5 rwtq gain from the initial pulls before we had to call it a day.

The 225s mirrored the 205s at every rpm to about 4000 rpm, then they started pulling away. Funny thing is, the motor now wants 15% more fuel, but was only making 1% more power. All we had time to adjust was fuel. We did not have time to mess with timing. Since the motor wants all that extra fuel, the power had to be there, I'm just going to have to make another trip to the chassis dyno to work the timing end. FWIW, I'm running 26 degrees of timing at peak torque and 29 degrees of timing at peak power. That's what the 205s liked. I'm not sure what the 225s are going to like. More timing? Less timing? Based on the increased airflow upstairs and the coinciding appetite for fuel, I feel the power once tuned, will exceed my prediction of 15 rwhp gain, but again, speed density tuning is such a balancing act. I picked up 10 extra rwhp by sharping up my 205 tune. I feel that with more time on the dyno and on the road, I will unleash all the BTUs that are hiding in all that extra airflow and fuel.

On a sidenote, my low rpm fueling was about 5% too rich, meaning the 225s don't want as much fuel downstairs (because of the lower airspeed I guess). Wierd: 5% less fuel at low rpm and 15% more fuel at high rpm. Needless to say, my VE tables are much more spread out than they used to be. I will report back after I have my tuning closer. Sorry we ran out of time.

So for those who look to the end of a post for the conclusion of a story, so far, I picked up 5 rwhp/5rwtq from 4500 rpm to redline over the 205s and lost 0 below that. With more tuning, we will find the rest of the hp. Looks very promising.

slt200mph

iTrader: (42)

Thanks for the post Patrick..I am very interested in the results of your experiment..can't wait to see what you get with a fine tune..

Drew778

iTrader: (2)

So, you gained 5 rwhp?

Patrick G

iTrader: (14)

So far, we've gained 5, but keep in mind, with speed density tuning, it's not as easy as bolting on a new head and watching the MAF account for the added airflow. Based on the demand for additional fuel at WOT, I expect to pick up much more than 5 rwhp. Remember, we had to bump my VE numbers over 15% at WOT to account for the added airflow at WOT. The power is there to be found. We just have to unlock it (with the spark and fuel the motor wants).

rosm187

looking to hit 500whp N/A 346? whats it run at the track, if u've run it yet

Patrick G

iTrader: (14)

500rwhp N/A with a medium size cam would be nice, but not my ultimate goal. I just want a super streetable package that makes strong power everywhere. I had it with the AFR 205s. I hope to have even more of it with the 225s.

calongo_SS

iTrader: (7)

Same compression with both heads?

Patrick G

iTrader: (14)

Yes, same compression. Just an A-B head swap.

zo6vetteman2003

iTrader: (1)

With the 225's there may be a drop in low end torque, according to what I have seen with a 346ci.

offaxis

iTrader: (19)

Great info patrick.. Keep it coming

Patrick G

iTrader: (14)

Maybe you missed it in my initial post. The low rpm torque and power curves are an exact overlay of the AFR 205s. In other words, there is no loss at any rpm anywhere...just gains.

SlickVert

iTrader: (5)

Patrick, sure sounds like there’s another 10 hp in it.
What lifters, rockers and valve springs are you running?
Is there any chance that you are getting valve float with the heavier 2.080 valves?
Did you rematch port the intake to the 225’s?
Good luck, you’ll find it!
Keep us posted.
Bob

Patrick G

iTrader: (14)

I'm running stock lifters and rockers. The springs are AFR 8019s. These springs are a little bit beefier than the awesome Comp 921s. AFR had these springs made for them exclusively and they rock. My valvetrain is actually quieter now. There is absolutely no valve float. I did not revise the FAST intake runners since the entry to the 205s vs the 225s are very close.

Louie83

iTrader: (3)

Interesting experiment, I'll keep an eye on this one.

The only problem I see is that your cam is matched to the 205's and I don't think that cam is capable of showing the full potential of 225's. I would think something in the mid 240's matched to the 225 would be more ideal, especially in the upper RPM's.

Patrick G

iTrader: (14)

I don't agree. My cam is .644 lift. Because of this, it will be able to better take advantage of the 225s superiority in the .450-.650" lift range vs. the 205s. A 245 cam with only .580-.600 lift wouldn't take any better advantage of these heads than my current cam (all this in my humble opinion of course).

badaSS346

iTrader: (4)

Where did you get those flow numbers? Tony M posted this.

These are not as dramatic gains as what you have and i just want to be sure that i am using accurate information to make a choice.

jrp

iTrader: (16)

i would assume that patrick flow tested his 205's vs the new 225's using the same testing apparatus and procedure. also, Tony err's on the conservative side with his numbers.

Patrick G

iTrader: (14)

JRP is right. Thunder Racing flowed my 205s before we bolted them up, then after we took them off. The flow comparison is of my old 205s vs. the new 225s on the same SF 1020 flowbench on the same day. FWIW, my 205s flowed within 2 cfm of what they did brand new on the same bench. Guess that's why they continued to make the big power.

badaSS346

iTrader: (4)

Even so, shouldnt tony's difference between the two still be about the same. For example at .600, patrick has a difference of +21 so lets say for arguements sake the 205's flow 300 and the 225's fow 321. Shouldn't tonys numebers still be about a +21 difference +-5? Im not trying to be a dick just want as accurate as info as possible before i would buy a 2500 set of heads.

Paul

Patrick G

iTrader: (14)

Two things to remember: Tony's flow numbers are of both heads unmilled. Both my 205s and 225s were milled .030". The milling affects the flow numbers perhaps more on the 205s than the 225s. Also, Thunder Racing uses a Superflow 1020 bench while AFR uses a SF 600. The numbers do vary from bench to bench. We wanted to see the delta from one head to another. That's what I posted.