OK....

I'm going to "peacemeal" all the test results as I will never have enough time to type all the info in one sitting, not to mention the post would be ridiculous in length.

First off, these are numbers at the crankshaft, NOT the tire, so for reference, the motor that was previously in my car (the stock short AFR 224/228 combination you guys have read tons of info on) on the very same dyno I recently completed testing the 383 on, put down 550 HP / 482 Ft/lbs.

Also, I think we should talk about the test parameters quickly and how they compare to having either (346 versus 383) engine actually installed in my vehicle.

First off, the results on the engine dyno (SuperFlo 902) were thru "typical" 1.75 inch long tube headers (approx. 32" primary length / 3' collectors) and 3" Flowmasters (not open exhaust). What's also importatnt to note is that installed in my C5, the 346 combination described above routinely put down 475 RWHP and 435 Ft/lbs to the tire (chassis dyno #'s), and I saw a handful of runs in the 480/440 territory, but we will call it 475/435 just to be conservative. The major differences I would note when trying to compare flywheel #'s and chassis dyno results would be the Corvette not "optimally" shaped long intake plastic airbridge and MAF with a small conical, slightly restrictive K&N filter (a negative factor for power output in the vehicle), and another large variable would be the different syle exhaust when we try to compare flywheel and chassis numbers (unfortunately the header I run in the car would not fit the engine dyno stand). I run the LG longtubes in the car which has VERY long primary pipes and a merge collecter, both of which are usually a positive factor in increasing TQ output, although on a more powerful, higher revving larger displacement such as the 383, the jury is out on whether those loooong primary pipes (almost 40") and the merge collector might start looking like a restriction at high RPM's. Although I would have much preferred to present you guys with ALL the data (chassis as well as flywheel #'s) at the same time, that would have meant you would be waiting awhile for any of this info, so for now, we can all benchrace and speculate what the final 383 combination will put to the ground actually installed in my Vette....I have my "air dyno" chassis numbers which I will share with you at the end of this thread, and I have tried to touch on most of the larger variables (that I could think of) which could effect the final numbers for everyone else's benefit that might want to take a stab at it. One thing is for sure, its going to either be a stout 383, or a VERY stout 383....I am certainly looking foward to the final results when installed in the vehicle.


QUICK RUNDOWN OF 383 COMPONENTS

Shafiroff 383 LS1 Shortblock kit (Balanced rotating assembly, race prepped fully machined block, blueprint and assembly done by myself)
Brand new 5.3 aluminum block
Eagle 4" 4340 Crank
Callies Comp Star Rods
Mahle -7cc pistons with slight inverted dome (only 10.93 Final CR)
Cometic .030 MLS gaskets (pistons were .002 in the hole)
Total Seal gapless rings (gapless top style)
Clevite "H" style bearings (un-coated)
ATI Super Dampner (only 10% under-drive)
AFR 205 / 225 Heads (both milled to 65 cc's)
Comp Camshafts (custom grinds, hyd. and solid....specs to be disclosed later)
QTP Billet Timing cover (2 piece....a godsend for quick camswaps)
QTP High Volume pump (ported by myself)
Crane Hyd. Lifters / Crower Solid Lifters
Crane Aluminum 1.7 Studmount Rockers (*new* 1.7 Shaftmount tested later)
FAST 90mm intake (ported by myself)
FAST 90 mm TB used for Dyno testing
36 Lb. FAST injectors

----------------------------------------------------

FIRST ROUND OF TESTING

Essentially the exact same combination as the 346 in my car and whose flywheel dyno results I shared with you above (550 HP/ 482 TQ), the ONLY difference being the larger 383 displacement shortblock.

Also, before I go any farther I just want to highlight the fact that the new 383 combination has almost four tenths of a point less compression than the 346 combination we are comparing it to. While that wouldn't make a huge difference, its quite obvious the delta between the two would have been slightly greater had the CR been exactly the same (I would approximate about 6 ft/lbs and perhaps a slightly better gain in HP).

TEST 1

383 Short
AFR 205 heads (65 cc chambers)
AFR 6016 cam (224/228 .581/.588 114 LSA)
Crane 1.7 Stud mount
FAST 90

Final Results 552 HP / 522 TQ (16.2" Idle vacuum....Smooth!)

TQ output @ 3000 RPM's 447 Ft/Lbs

(NOTE: The 346 generated 15" of idle vacuum in the exact same configuration.)

Summary:

KILLER street piece for a conservative guy....total sleeper, very street friendly with a stockish idle. As expected, area under the curve was impressive compared to the smaller 346 with the same induction, and a big increase in TQ was noted immediatly. The results were inline with what I expected...I was questioning whether the larger engine with the same induction/small cam might make less peak power and was glad to see it came in exactly the same. Big increase in TQ was a no-brainer. Peak power occured around 62-6300. Peak TQ was flat around 5000-5200
Note that as low as 3000 RPM's, the engine was still producing almost 450 ft/lbs of TQ (447 to be exact).

-------------------------------------------------

TEST 2

Installation of larger Hydraulic 234/238 (.598 / .605 114 LSA)

Everything else exactly the same as Test 1

Once again, while we certainly could have featured a much larger grind (especially on the larger displacement shortblock), to me it's more impressive to put up big power numbers thru conservatively cammed engines that have properly matched components and tend to be better "all around" performers. While it's certainly fun to have the nasty burger stand idle, the flip side of the coin is that same combination will protest at lower RPM's in top gear, the additional cam overlap obliterates fuel economy, and if your doing any serious amount of driving the downsides of the big cammed stuff becomes all too apparent. I will share with you the results of a slightly larger Hyd. grind shortly, but the average power of the smaller 234 stick had it all over the bigger cam (I think the engine would have responded better to the larger grind with a higher static compression ratio).

Final Results 578 HP / 520 Ft/Lbs (11.7-12" of idle vacuum)

TQ output @ 3000 RPM's : 440 Ft/Lbs.

Summary:

This cam proved to be excellent in overall power....while there was now a noticable slight chop @ 900 RPM's, the engine still had excellent throttle response and lost practically nothing in low speed AND peak TQ output (only down 7 ft/lbs. @ 3K, down 2 ft/lbs. peak). It's obvious we were starving the 383 for air with the smaller cam, as there was barely a trade-off in the lower and middle part of the power curve while finding an extra 26 HP across the top. We were hoping for a 20+ gain on power output and was very pleased with the results this cam provided. Unless you were looking for a very stealthy package and a little more fuel economy from the reduced overlap (as well as some additional snap in part throttle), the 234/238 would definately be a better choice in this particular application....with a handful of guys on this board probably opting for a little more but that's where the trade-offs start to creep in as you will certainly see later. Whether those trade-offs are worth the extra peak power is certainly individual and application sensitive.

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NOTE: Continue to scroll down this thread for PART II and the rest of the 383 test results....

Tony M.

 

Cool! Need to try bigger cams and see what happens

 

Is it later yet?
600hp 383...maybe one day, until then

 

Nice numbers, everyone wants a 408 or a 402, but it is nice to see a 383 making good power

 

Tony,
Thanks for listing the vacuum @ idle numbers. That is a first!

 

pretty stout numbers dude Seems like its got alot more potential too

 

Yupper... That is what I am waiting for....

 

Man I would like to see what that 383 would make with like a G5X3/205 heads and a bump in compression up to 11.25. Please Tony try a bigger stick for us guys with the 205's!

 

How much for all this as in a crate motor. Also how much RWHP would you say this would be?

 

Guys...

I have already done most of the testing you would like to see....needed to get access to the computer disc to provide you with additional info from the 60 something pulls I completed spanning over four days on the dyno (in 100+ degree heat I might add.... LOL)

Should have time to hopefully post the rest of the results later...

Tony M.

PS....(Note to self) No more heavy dyno scheduling @ Westech during the hottest months in CA !!!

 

got a pic of that massive under the curve torque?

 

Awesome numbers.

 

More test results updated in my first post....I will continue to add and edit information as time permits....Should have all the info and possibly a gragh or two (with a little help) by the tail end of the weekend.

Tony M.

 

Tony what was the installed centerline of the cams?

 

Id like to see a dyno with the ls2 6L with afr 225 heads, ms3 cam, and fast intake. I think the 4" bore might be worth more than the 4" stroke.

 

To keep all the cams on a somewhat even playing field I decided to grind them ALL on a 114 LSA and install all of them straight up to enhance higher RPM power knowing I would be running somewhat conservative cam timing. I checked every cam's installed position while doing all the testing. I prefer a 114 LSA for drivability and a cleaner idle and I have not seen many instances where actual "peak" power figures are much compromised (versus say a 112 or 110 LSA). I also like the way the wider LSA carries power past peak. Of course this is subjective to whom ever you speak with and different engine builders will always have different opinions.

Tony M.

 

awesome to see you doing testing like this. nice numbers.

 

Seems I ran out of room to edit and add information in my initial post (THAT'S a first....LOL), so the test results will have to be broken in half and continued here....

------------------------------------------------------------------

TEST 3

Installation of 225 heads (65 cc chamber....same CR)

Once again, every other aspect of Test 2 remains the same....essentially this is a test featuring the 225's versus the 205's with the same 234 / 238 Hyd. roller cam.

Final Results 585 HP / 523 Ft/Lbs. (Same Idle Vacuum as Test 2)

TQ output @ 3500 RPM's : 449 Ft/ Lbs.

Summary:

This test was interesting, and really enforces just how effective the smaller, high velocity 205 head actually is (much like you guys have witnessed over the last 12 months or so). While I had gone into this test hoping for 10-12 more HP upstairs, the more time I spent afterward thinking about how the 225's were actually being tested, the more I realized this engine wasn't ideal to try and show off their attributes. The first thing is that when I think of the 225's, I usually find myself "benchracing" the flow numbers they provide on a 4" or larger bore (where they are much more effective). The reality is that on the 3.900 bore, the larger 225 flows about 10 CFM better than its smaller brother....not the 15-20 CFM disparity you would see on a larger bore combination. The other situation in this test which I feel somewhat compromised their potential was the fact I was forced to mill them to 65 cc's (below my own guideline I have been preaching to you guys which is 66 cc's). I was trying to get as close to 11 to 1 as possible, not to mention I didn't want the 205's to have a compression advantage. Last but not least, I have personally documented that alot of the larger flowing heads potential is lost thru the typical plastic intakes we are currently forced to run, and even my ported FAST is restrictive enough to "lop off" some of the extra flow the 225's actually provide. All things considered, the gains seen in this test (as well as the slight loss of low end TQ) make alot more sense when you carefully analyze all the facts.

I feel a larger bore, larger displacement engine would be a better way to showcase the larger heads true potential, but none the less they got the job done by increasing the "ante", ultimately getting me closer to the 600 HP goal I was trying to attain.

-------------------------------------------------------

TEST 4

Same 225 heads....Swap to larger 239 / 243 Hyd. roller. (.650 / .660)

NO other changes versus Test 3

Final Results 594 HP / 505 Ft/Lbs. (10-10.5" of idle vacuum)

TQ output @ 3500 RPM's : 432 Ft/Lbs.

Note: TQ peak occured @ 5600 RPM's....Power Peak @ 6500 RPM's

Summary:

Before you guys start cheering about the extra power, make sure you take a look at the area under the curve. While this camshaft certainly showed its stuff upstairs (it was still making 590 @ 6700 RPM's), the lower part of the curve took a good hit, and even the peak TQ figure was almost down 20 Ft/Lbs. If you were purely concerned with drag racing and sidestepped the clutch at close to 6K or better, this cam would perform well, but as I was trying to feature a more balanced package here, this cam would not be the cam of choice. I think it also would have worked better with a little more static compression, but for that matter, so would all the other combinations I featured as well. This was a good test in the sense it shows clearly that there is a point you reach when you have chosen a cam that's just a bit too big. The smaller 234/238 made close to the same power and was simply far more efficient on average which was also clearly evident by the better V/E #'s and stonger TQ for the better part of the power curve. I will do my best to try and get some actual curves in this thread when I have some time.

--------------------------------------------------------

TEST 5

Solid Roller time.....(accurate valve motion is a good thing!)

Same test as above with the insertion of a mechanical 242/248 street roller (.646/.653 Lift....114 LSA) and a set of Crower solid roller lifters with their "HIPPO" option....stands for high pressure pin oiler....a great move for reliability on the street.

The moment of truce.....would the semi-conservative solid roller get me to the 600 mark I had my sights on. Considering it was technically smaller than the big hydraulic and probably closer to the 234/238 when you account for the lash (also evident by similar idle vacuum), I was confident I would be close but I wouldn't have bet lunch on it....LOL

After seven pulls between 597 and 599.4 HP (literally!), the 8th time was a charm putting up exactly 600.0 HP and 519 TQ....thought I couldn't buy a 600 number for a little while there....it was actually pretty funny at the time.

Final Results 600 HP / 519 Ft/Lbs. (11-11.5" of Idle vacuum)

TQ output @ 3500 RPM's : 444 Ft/Lbs.

Summary:

I was extremely pleased to nip the 600 mark with a reasonably docile, mild compression 383 street build-up. Not to long ago hitting those kinds of numbers with the same cubic inch, high compression, and a big race cam would have been an accomplishment. Technology marches foward and affords all of us the opportunity to build a VERY dual purpose vehicle...one capable of comfortably cruising the streets as well as putting down some serious numbers at the track. While it is also obvious a slightly larger mechanical cam would have put up even more, much like the comparisons of the larger hydraulic grinds, a larger mechanical would have more than likely become a debatable compromise if your goals were to build a powerful well-rounded engine.

---------------------------------------------------------------

TEST 6

(Bonus Test which turned out to be a nice surprise)

Installed a prototype set of Crane's 1.7 Shaftrockers for the LS1 which have a completely "needleless" bearing/trunion design built into the rockers. They have a proprietary composite bearing material that rides on a thin film of pressurized oil much like the principle that lubricate all your rod and main bearings. Crane claims the friction benefits alone are worth a reasonable gain in power coupled with the added rigidity of a shaft mount design which eliminates rocker stud flex completely. These are NOT a "bolt-on" and require cylinder head machining, some clearancing of the cylinder head and stands, as well as valve cover spacers to clear the rocker/shaft assembly but the results are worth the time and price of admission if your looking for all the money out of your combination.

With NO other changes to Test 5 except for swapping out the Crane studmount 1.7's to their new 1.7 ratio shaftmount design we witnessed the following results:

FINAL RESULTS 611 HP / 523 Ft/Lbs (Same idle vacuum as Test 5)

TQ output @ 3500 RPM's : 444 Ft/Lbs

Peak TQ @ 5600 RPM / Peak HP @ 6700 RPM

Summary:

Impressive....10-11 more HP with no loss of bottom or midrange TQ whatsoever. In fact, the curves were essentially "layovers" from 3000-5400 RPM's....after 5400 the new shaftmount design just started slowly pulling away from it's studmount brother showing a clean 10 HP advantage from 6600 all the way to the end of the dyno test (7200 RPM's) where the engine was still generating 597 HP! In fact, I was more blown away by the solid roller's curve than I was at the shear peak numbers. With the shaft system in place, the engine generated 600+ from 6200-7100 RPM's barely showing signs of quitting going higher. I will probably shift this combination at 74-7500 in my vehicle when I'm looking to "ride the power crest" trying to achieve my optimum ET at the track.

Can't wait to see what she does in the car....Give me some time and I will work on possibly getting some graghs up here.

I'm all typed out!!!

Regards,
Tony Mamo
AFR Sales / Product Design
(818)890-0616 Ext. 109

 

Alll damn good info....

Hey did I miss what kind of water pump you used???

 

Very good info. Great for me sence i still have stokc heads and a 224cam on my 383 right now.

Tony, will AFR maybee be offrering a heads cam package lets say some 205's along with a cam of choice from yall considering you have done lots of testing on this. just woundering but if not i will be picking up a set of 205's within the next 4-5 months and a cam from somewhere