I finally took my car to the dyno to see how much additional power I received from the circa 2005 AFR 205 heads my friend gave me last summer.

The results are in.

474/414 AFR 205 Heads
451/404 Stock heads
23/10 gains peak,
25+ torque gains under the curve

First some facts to consider in the interest of full disclosure for those pondering these numbers.

1. This was a different shop, same dyno. The last dyno shop I used has closed.
2. I am now running heavy repro 19x12 wheels with 345/30/19 tires vs. last time with stock wheels and non-runflat tires. Add'l weight of about 20 lbs per wheel.
3. Last time I had 3.90 gears vs 4.10's now, difference shouldn't matter much.
4. Weather was better last time, freakishly low 34% humidity for us and 30.34 baro 81 degrees vs 45% and 29.96 today and 77 degrees today. Correction factors should accomodate but I believe you make more power with higher baro and lower humidity despite correction factors. Uncorrected the results are 480/419 vs 463/414, note the smaller variance of 17/5. I picked a good day to dyno last time.

My biggest takeaway from this exercise was wow, dyno tuning is a lot more valuable than I'd thought. I've been tuning myself for years now and had the car pretty dialed in from tuning at the track, or so I thought.

But look at run 1 vs run 5 today - I gained over 20 ft lbs of torque nearly across the board from tuning on the dyno, taking out some timing and adding some fuel down low and adding a bit of timing up top! The dyno tuning gains are quite a surprise. Obviously I could likely get a few more hp if I leaned it beyond 12.5 AFR...but I have 61,000 trouble free miles on my daily driver and I'd like to keep it for another 61,000 miles at least!

I'll be eager to hit the track again. So far best run with the AFR's and the same tune as run 1 was a 10.95 @ 129 vs best previous in my signature.

A question arises as when my stock OE clutch with 61,000 miles and 462 runs to date will finally say uncle. Last event I had 3 runs, 1.57, 1.59 and 1.57 60's, still learning the new launch technique. So far haven't had the stones to do 100% throttle launches like last time, which was netting me 1.49, 1.51 & 1.53 60's.

Some graphs:

Uncorrected


Corrected

 

you should get some great 1/4 times

 

Glad you had successful results. I am sure you'll realize some solid gains at the track now that you picked up all that power under the curve. 10.8s are all but certain now

I'm still not sold on adding heads to these cars. The power increase doesn't seem worth it for the cost, in my opinion.

However, if you want to go as far as you can go N/A then it's a necessary modification to tackle

 

I hope so! But I think your and Andrew (DSP300C)'s records are safe. Andrew has 531/483 dyno results from his G6x3 and TF225 heads w/ electric water pump. That's 57/69 more rwhp/rwtq than me! I don't think I stand a chance with my OE clutch compared to that power to get lower than 10.58@131. Particularly down here in FL where it's 81 and sunny today, January 19th (good for top down cruising!).

You are correct. The heads are definitely up there on the "diminishing returns" category. But, as you note, as the power goes up the returns diminish and at some point they are the next mod to do. That's why I waited for a free set of heads to put them on! Well not exactly free, I had to buy him some little items as he got his car ready to sell.

 

"Free" heads are hard to beat

 

Well, I paid in sweat putting them on at least!

 

Joe those numbers aren't to bad for a 205cc head with a med sized cam.

 

So what mods would you suggest that would not include heads ?

I'm still throwing a bunch of ideas around on my 2005/A4 car...
I honestly just don't feel like pulling heads off.

I think I'd be happy with 450-480hp at the rear wheels with decent street manners. That is stock Z06 territory.
Then add a bottle of nitrous and call it good.

 

Looks like Florida weather/work to me!

Congrats! Get that sucker out to the track to take advantage of the "cooler" air we only get a few months of the year down here in the south next to the water.

 

Great numbers Joe, time to hit the track with some cooler weather to post 10.7x or 10.8x.

 

So when's the next big track day going to be?

Personally I'd always just go for a big cam-only car + nitrous or put some form of forced induction on.

 

If we ever get a cool snap I'll hit the track! It's 80 degrees today, January 20...just nuts! Normally we have several cooler days by now but this year there's only been one good track day and another fair one.

Dragracer Art, your goal of 450/480 is possible with a cam only...but be aware, really big cams have some drivability issues, particularly if you don't self tune and spend a ton of hours with it, with an automatic. Ask Theofel about that. At the lower end of your range you'll be really happy with your car. Ask Justasheet who has precisely what you want. Your power goals are good - if you shoot higher, you'll have no street traction unless you run drag radials all the time, and that keeps the car from cornering like a Corvette.

It's true that the last few rwhp/rwtq for a given displacement get more expensive as the first few go up, it's worth looking up in this thread at It's Stock's signature - we were pretty close to the same when we were cam only. But look at the gain he got from his big cam when he put some big heads on it!

Starting with our pretty equal baseline with stock head 451/404 and 440/417, I got 23/10 peak gain, he got 78/51!! That's pretty dramatic. EDIT he's on a Dynopack dyno so not sure how comparable our numbers are. Still his 131 trap speeds are stout!

 

You don't have to tell me...it's mid 70s in Houston

 

Awesome results!

The G5X3 loves those heads!

 

Thanks Anthony! Your cam has been a solid performer for years for me now...turning my docile daily driver into a 10 second machine (with supporting mods).

I also want to publicly thank you for support well after the sale. Even though it was 5 years after I bought the cam from you, you jumped in on my thread and answered my technical questions there, and again on the phone.

Something to be said for a vendor #1, in business for a long time, and #2, providing good service well after the sale. Actually the two go hand in hand. :yes nod:

Thanks again.

 

That's what we are here for!

Let me know if you ever need anything!

 

Very cool Joe. Good work on finally getting to the dyno.

I thought you'd be closer to 500whp but the dyno is just a tool and the dragstrip doesn't lie. Your 129mph trap is awesome, but I think you can do better than that I'd like to see a 10.75@13x when we finally have some good air roll through.

 

When you get a sec, can you email me 1 or 2 of your logs with the 100% throttle?

 

Hmmm... I'm at 420/420 unlocked with a 2006 C6 with AFR 205's and a 224/224 115 cam. I'm adding a Fast 102 intake (unported) and a 3600 converter that's sitting in my garage soon.

I have no track times yet due to the fact that I have not installed the parts mentioned above. I have been thinking of getting a larger cam for more HP but this 224 drives like stock but has a little more grunt.

 

Congrats on the gains Joe! Gotta also remember Andrews car is over 200lbs lighter than yours Looking forward to living vicariously through your faster track times as they've shut down Dallas Raceway
FWIW when I dynoed my 315/30r18 on heavy repros vs the 20lb lighter 275/40r18 on stock Magnesium wheels it was a difference of 10hp