0Tony Mamo @ AFR

While the recent trend of some cheerleaders seems to have looked the other way (with no hard data actually warranting most of it), don't discount the tried and true....still the original aftermarket LS offering....and still arguably the best. Especially if your interested in enhancing your entire driving experience as well as looking for the obvious gains in peak power and torque. No other aftermarket head will boost the bottom of your curve like the AFR 205, and few can match it upstairs although now obviously you guys have a handful of other choices that will still produce excellent results (TF, ETP, etc.). However, the AFR is still the only one to offer a direct replacement bolt on (accepts stock rockers, has OEM valvetrain geometry, stock height valve cover rails etc.) and is CARB legal which is a nice perk depending on local emissions laws.

Whats got me fired up? Besides the last couple of months of opinions and posts I just have to grin and bear (knowing most of them stem from comparing advertised flow data which is a topic I would really like to split wide open one day), I just got back from the dyno last night....late last night I might add, and once again a simple combo with AFR 205's (that any of you could copy) has put up numbers that IMO exceed anything I have seen remotely comparable based on displacement and the sum of its parts. Sure its an optimized combo I personally picked most of the components (and built the engine in this case), but it still represents an effort that doesn't cost cubic dollars and performs like it does.

Check out this dyno gragh....off the same dyno I have personally used for my testing over the last two years or so (Mike Haddad Performance) so before you guys call BS, note my car has ran the number to back the dyno results and most of you guys have seen video which clearly shows how explosive that package was.

This is a 91 octane 383 that has a smallish cam (hydraulic roller 234/238) one of my ported 90/90's, about 11.35 to 1 CR, and a set of 205's that I also did some moderate porting work still retaining the 205 cc inlet port (most of the grinding was focused in the combustion chambers). The head "only" flowed a legit 304 CFM with exhaust flow in the 245 range. Big area under the curve and a tremendous amount of airspeed which most of you still just casually glance over (that is what packs the cylinder with more air/fuel).

Here is the curve....it exceeded the 525/500 mark I was hoping for rather nicely....look at the low RPM torque figures and how long it carries over 500 RWTQ



Also note it was approaching midnight last evening when we wrapped this up and this is NOT a set on kill tune....in fact there is probably a few more ft/lbs and 5-7 HP in it if I was really looking to punch a number. The A/F ratio is safe in the mid/high 12's and this pull only had 26' of timing. Every LS engine I have built has liked 28-29 for best peak numbers but seeing as this is for a customer and not for me personally, I will probably leave it very safe which is the graph you guys are looking at right now. This car is also his daily driver which is one of the reasons I chose such a mild cam.

BTW, peak torque is a staggering 508 ft/lbs (that's very good for an engine 20 CID larger and decent for a 427 for that matter) and peak HP came in at 535 on the dot. In spite of the small heads and the small cam this package still peaked nicely at 6500 RPM's and when we get finished tuning it I will likely post another graph showing the full curve to the 7000 RPM point I anticipate will make the best shiftpoint.

Whats also very cool about this test is the fact it is in a VERY similar driveline to my own....a C5 with a lightweight clutch/flywheel combo (an RPS dual friction single disc with an aluminum flywheel) and this car had a slight advantage over mine because it still has the factory 3.42 ring and pinion which tends to dyno a little better than an aftermarket unit with steeper gears. This package also benefited from a smaller header (the LG pro's which are known to make big torque) versus my larger (and shorter) 1.875 primaries, and obviously my former package was a solid roller with larger 225 heads, once again both moves aimed at bolstering the top numbers at the expense of some bottom. In actual size, when you account for the lash, my 242/248 solid acted and idled extremely similar to the hydraulic grind in this test, but the smaller head with its higher velocity charge would actually reduce some of the negatives associated with the overlap of a performance cam. I cant wait to drive this...it should actually feel alot more explosive than my former package from off idle to 5500 RPM or so and honestly it doesn't give up a whole lot to mine upstairs. Not to mention this package has zero maintenance due to the fact it has a hydraulic valvetrain versus a solid.

Next time Im at the dyno I will try and get data that compares some of the even lower RPM points where obviously the gains from the current package would gap up even more. Check out the actual overlay of both my former 383 and the new engine (built around my former shortblock freshened up)



More to come....I will try and fill you guy in on the rest of the details as the weekend continues to unfold.

BTW, I'm sure a few of you will point out the fact that I also ported the 205's and I don't discount that it was likely worth 5-10 ft/lbs and 10-15 HP, but when the smoke clears if I tune this car like any other shop would before posting to get it to punch a big number, even if you subtract those figures to simulate the same combo with out of the box 205's the numbers still rock for a mild mannered 91 octane pump gas 383....

Cheers,
Tony

PS....A BIG thanks to Mike Haddad and crew who stayed very late on a Friday night getting the car finished up and hooked up on the dyno. I even gave him an out saying I would come back on Saturday but the guys there were as psyched as I was to see what it would make. While I provided the complete rebuilt engine, the guys at Mike's shop did the entire install and tune as well as some exhaust work and a few other upgrades as well (injectors, fuel pump, etc.)

PSS...Another big thanks and congrats to the owner Rick Duncan.....
(NO Rick....my car is now in pieces and you cant have yours back anytime soon!)

Here is a pic of Rick's used 205 heads that I freshened and went thru as well as a shot of the 383 longblock shortly before delivering the complete engine to Mike

Ikester

No question....I have quite a few members here that can attest to this after taking them for a ride. After learning that heads is a critical choice I knew I couldnt spare any expense. Then combining it with a well matched cam made my car a whole new animal.

Gray Ghost GS

Tony - I've been running your AFR 205 heads (shaved to 61cc) on my LS6-based 383 with outstanding results! Very strong numbers and a consistent performer on the road courses. Thanks for a great product! Mike

ajg1915

Nice numbers and power curve.

I wonder how much of the extra torque comes from being stroked vs stock ?

0Tony Mamo @ AFR

Thanks guys...

Torque is all about displacement (one of the largest contributors anyway), but high flowing efficient cylinder heads, the right cam, and the correct supporting cast if you will all come in to play. In fact most people think bigger motor equals more horsepower....thats actually not true....a bigger motor will only guarantee more torque, not more power (assuming the same heads, cam induction, exhaust, etc, the HP would actually be similar but happen at a lower RPM.....peak torque would be higher though as would AVERAGE power with a big boost to area under the curve)

This particular combo exceeds in the torque department however, producing the highest torque from a 383 pump gas engine I can ever recall seeing. As I mentioned in my thread....solid numbers for engines with a lot more displacement. This engine is producing around 1.39 ft/lbs per cubic inch (evaluating crankshaft numbers).....that is a big accomplishment.

-Tony

Cobra4B

One of these days I'm gonig to get a set of your heads to go with my G5-X2 cam... my cam really comes on at 3500 rpms so I'm hoping some nice 205s balance out the torque curve a little bit

vettenuts

Hmmmm, seems like my heads could grow into a larger block later

Can't wait to start my install next month.

ssmith512

Ahhh DUDE!! You're killing me by posting these killer numbers out of a 383!!!

These numbers are just simply amazing. I can only imagine the head snapping action this car produces when you stand on the gas pedal from low RPM's.

Fantastic, simply fantastic. I have too long of a wait, but it will be worth it!

WKMCD

Wait just a minute Tony...Are you saying that the flow and dyno numbers that get thrown around here and other LS forums are BS?

Say it ain't so..

Gray Ghost GS

Tony, what were these 205 heads decked to for this build to achieve your compression ratio? Having mine ported and polished may be a good winter project for me.

Mike94ZLT1

Tony- If I don't yank my 383 in favor of something different I will definitely be calling you for a new head and cam package, do you think we could do better than 525/500 at the wheels with a more aggressive cam than the 234/238 or would I be sacrificing too much driveability? I have a 6 speed with 4.10's, so the gears would help!

CTD

Tony
If I would have known what you were up to on Friday I would have never bothered you with my Cadillac Racing lifter delima, although a testament to you still willing to help even though being buried in another project.
Awesome results.
I'm going to order another set of CRL's (not from the original supplier) so should you ever hear of another problem like mine I will have 15 spares. Another reason is my cam timing is 1.5 degrees advance, so I need to order an adjustable timing set.
Tx's
Dale

AU N EGL

Kevin. You know that. When was the last time you saw an "SAE Corrected" dyno sheet on LS1 tech ?

phils C5 vette

I want one

402s are for white corvettes

WKMCD

Tom,

Even then, you're at the mercy of the integrity of the operator..That's as big a problem as the mechanical differences between dyno's. Back when I had my shop building GP bikes I had a dyno. When some customers came in and wanted a dyno session they would ask "What do you think it will do" Standard answer for the toady's was "What do you want it to read" It's not that difficult to "spin" a dyno.

WKMCD

Fixed it for you...

(Hijack off)

k-mart

Great results!

I'm interested in the timing you used because I recently moved to an area with 91 octane exclusively. I'm running 205's milled to 59cc with a GM MLS gasket. On 91, my car is pulling up to 9 degrees of timing at full tilt with the tune set to 28 degrees. Would it be beneficial for me to drop timing closer to 24-26 degrees as you did here?

Thanks,

Kevin

Switchbarrel

Funny you should say that, the recipient of this motor is also white.

-Rick

0Tony Mamo @ AFR

Every build is different based on desired compression ratio, piston dome or dish volume, head gasket thickness, deck height, etc. In this case it was a 63cc chamber after I ported them and milled them to my target (with a -7 cc dish yielding 11.3 ish to 1 CR). The porting work I do opens the chamber about two cc's which lowers the CR, but I can mill whatever I want off the head to completely offset that or even make the chamber smaller for more compression.


Other factors are involved in making the power this package produced....without the right clutch/flywheel, induction, headers, etc. you can build a similar combo and fall 30 RWHP short. In fact that is a very common phone call for me...."Hey Tony, I copied your package but I'm 35 RWHP off". My response....."Did you have one of my ported FAST intakes? (no)....."Do you have a lightweight clutch/flywheel combo? (no)...."Do you have the same headers?" (no)...."Were you running an EWP?" (no) You guys get the picture. If your going to copy a particular combination and expect the exact same results (or close), you have to copy that package completely or expecting the same results is not a very realistic outcome (Its funny hearing peoples reactions when I walk them thru the 30-40 HP they missed in all the small details).

Mike...To better answer your question in a fashion I know would be more accurate....sure, if we added 5-10 degree of duration to this particular package(which we have already quantified), peak torque would likely drop around 10 ft/lbs and peak HP would climb close to 550, BUT, the package wouldnt nearly be the killer all around performer it is now. That extra 20 compromised some of the insane low end torque and throttle response....its all going to be a trade off unless you build a bigger engine to get some of the lost bottom of the curve back.


Kevin, alot of things could cause what you are experiencing (related to the tune, the sensitivity of the knock sensors which you can address in the tune, too small a cam for a 59cc head, etc.)

In fact speaking of that, what cam are you running and did you fly cut your pistons or are you running aftermarket that have valve reliefs because a 59ccc head without valve reliefs gets you some pretty stout CR numbers.

Bottom line....need more details to help you out but would prefer not to derail this thread with them....use the PM feature or just call me at AFR


Rick....EVERY one of your vehicles is white.....LOL

AU N EGL

Oh I know.

and why my little 400 rwhp with a 224r cam can still take many bigger cam cars out of tight corners and up to 120 mph. Just those bigger cammed and cubed cars eat me alive over 120 mph on long straights. Then in braking zones and tight corners I come right back.

One day an new engine build. hopefully this winter. and YES I would put Tony's heads on. Maybe a LS2 402 with AFR 205 heads. Give me LOTS OF TORQUE to get out of corners and up to 150 mph ASAP.


Tony, I showed the pic of your heads to my wife, and she said they look like jewelry.

I said, They are