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557" AFR 300's Street build 750+ HP @ 6,100

32K views 45 replies 11 participants last post by  nedceifus 
#1 · (Edited)
This is our long awaited AFR 300 bullitt headed stroker build. We will be using the heads and intake as delivered for a baseline.

557 for Project 12.99 LTD (750+ HP @ 6,100)
By design this build was meant to have the same power-band and peaks as the current 460 as well as the same DCR.


4 bolt CJ D0VE-A block bored and deck plate honed.
Main line honed.
Scat 9000 4.5" crank
Scat 6.7" H beams with 8740 bolts.
Autotec custom AFR pistons 22 cc dish
11.7 to 1 static c/r 9.2 to 1 DCR. Pump gas 92/93 friendly.
External balance due to 6,000 rpm peak.

Canton 15-764 road race pan
Canton 15-763 pick up for M84 D HFD (paul kane) oil pump.

AFR Bullitt 300 cylinder heads
Comp Ultra pro magnum XD rockers 1.80
AFR Dominator flange intake
Comp carbs 1050 3 circuit street dominator.

Engine pro billet timing set with thrust bearing.
Custom comp roller 3 pattern HR cam 252-254 / 266 @ .050" 110 Lsa 106 Icl
Comp 936 16 solid roller lifters

Smith brothers push rods. 3/8" Length TBD.
Comp cams Ultra Pro Magnum 1.8 rockers.

New Engine quest timing cover
Performance Quotient Aluminum Water pump.

80008 Professional products Damper
OEM hatchet

D/S distributor with bronze gear.

Blue thunder CJ valve covers

Targeted output.

700 Tq
680 to 700 HP at a street friendly 6000 rpm


Actual output

736 TQ
755 HP @ 6,100 rpm with 2 1/4" dyno headers

733 Tq
744 HP @ 5,900 rpm with 2" dyno headers


I felt that the dyno correction factor was 2% too high so I corrected to what I feel are more realistic numbers based on weather conditions.

The combo made a best pull of 729.7 HP UNCORRECTED.

See our FB link in signature line for more pics and dyno vids.



S :D
 

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#2 ·
Thank you for the effort!

It certainly looks like a very very strong pump gas build.
The added intake duration (2 degrees ) was on the long intake runner cylinders?

Any intake manifold work? or OTB?

I havent seen what the intake port openings look like. I know the Victor 460 needs alot of work.

Cheers.
 
#3 ·
Yes the additional duration is on the corner cylinders.
I was surprised at the power given the relatively short duration numbers.

Hit the FB link in my signature for pics documenting the build.



S
 
#7 ·
#6 · (Edited)
This is first and foremost a street engine so keeping lift and spring pressures reasonable for longevity was part of the build criteria. Hydraulic roller lobes and the open spring pressure of 487# will live on the street with solid roller lifters. The spring pressures required even with the EX street solid roller lobes is really hard on lifters.

Given that the 2.25" primaries showed better power only above 5,600 leads me to believe that a 2" to 2.125" step might be the ticket. Unfortunately I only have 3 sets of BBF dyno headers.


S
 
#10 ·
The water pump is a nice piece with proper flange location. Time will tell with regard to longevity.

I tried 28, 30 and 32 degrees. 30 was best.

I have dyno'd a very similar p-51 headed combo with out of the box castings, D port matched dommy victor, HVH super sucker, 1050 Comp carbs dominator, 260 / 266 EX street roller (XR298R) and 10.3 to 1 c/r. 704 TQ and 699 HP. In all fairness matching static c/r would add about 30 HP. I feel a more direct comparison would be to a ported pair of P-51's with a 2.300" intake valve.

This combo beat expectations handily vs my experiece with our ported SCJ's and P-51's. Take that as you will.
I bought two pair of P-51's for my personal builds. They are still on the shelf as I wanted to try the AFR's.

We will dyno more crate combos with the AFR heads which will give better insight into how well they perform. I always provide cam specs, hp / tq peaks as well as dyno stp correction factor to give context to the build and its capabilities.




S
 
#12 · (Edited)
Given the flat hp plateau after peak I'd suspect shifting at 6500 rpm, which is what I used for minimum intake port cross section computations, will be perfectly safe.

Solid roller lifters on a hydraulic roller cam provide for a remarkably stable valve train without extreme open spring pressures. I saw no issues with loss of valvetrain stability in the dyno numbers to that point. Lash is .005" hot.

To be frank I will know more when engine is installed.

At the track I shift the currect 460 (6K hp peak) in the LTD at 6,600. Same type of valve train set up.




S
 
#15 ·
Retaining the current convertor which flashes to 3,450. I fully expect it to increase.
Keeping the 3.50 ratio but need to get a better locker, axels etc.
Wider steel wheels and more tire TBD...


To be frank this is more engine than I was looking for :D.


The engine is back on a stand. I have been contemplating a Torker 2 since the beginning however getting reliable numbers out with the AFR pieces was my primary goal with this build.




S
 
#17 ·
Did you have to do anything to the (I think) Blue Thunder valve covers as far as clearance goes inside of them?

As noted in the FB album the BT cast valve covers have to be clearanced just as with the SCJ and P-51 castings.
Using a 1643 felpro (thicker) helps. The baffling has to be clearanced for poly locks as well. Kind of a pain in the ***.

The motorsports tall valve covers fit with no mods.



S
 
#19 ·
Pad heights are similar though I would have to actually measure.
Yes I saw the post and the link to this post in that thread. Straub has offered no build specs as of yet.

With HYDRAULIC ROLLER LOBES and only 487# open spring pressure a rocker stud girdle and 7/16" pushrods (especially) are overkill. .083" wall 3/8" are fine. If I were to step up to the next largest hydraulic roller I have in my catalog I might opt for .120" wall 3/8" pushrods. If you look at the pushrod holes in the AFR castings... a 7/16" push rod is going to be a tough fit I promise you.

Would a stud girdle help stabilize the rocker studs and maybe make a few hp? Yes however I do not have clearance in the LTD for tall valve covers...


This is a simple hydraulic roller lobe street build that just happens to make really good power. The RPM and spring pressures are street friendly and not hard on parts. No need to complicate things. My build philosophy does not sanction the use of .750" lift solid rollers in street engines like has been argued for by a reader on our FB page. :eek::eek::eek::eek::eek:




S
 
#20 · (Edited)
I like the KISS rule aswell, thanks for sharing, not many go indepth like you do and show details with pics,

Here is a basic rundown from the other build......i was surprised at the timing!!

BBF 512 with 11 to 1 Compression
Box stock AFR300 heads
AFR Intake
1050 Carb
Straub Solid Roller custom 260 duration
Morel Needle bearing lifter
7/16" Pushrods
Goal was 700HP

Torque
3600 699.3#/ft
5000 738#/ft Peak Torque
5700 698#/ft

HP
5000 rpm 703HP (Breaks 700)
6500/6600 773.2

36 degrees of timing
Mix of 91 octane and 110
 
#21 · (Edited)
I go into depth to allow for context and comparison.

I am following the other thread as well as it has a link to this thread.

The early evidence more than suggests the castings are capable performers.



S
 
#22 ·
Scott,

If you where to compare the off-idle torque and throttle response in comparison to a 460 with stock ported heads, Performer intake, 750 Holley, headers, 10 to 1 compression and a 220-ish@0.050 cam, would this build with a single plane intake have equal or better performance down at the low-end?

Thanks,

Dave
 
#27 · (Edited)
Dave,

Given that the engine was designed to duplicate the 460 currently in the LTD its off idle and tip in characteristics are similar to this engine. The additional duration and resultent overlap keeps this engine kind of snarkey until about 1,500 rpm. Throttle response on the dyno was excellent.

To your question.

The comparison you reference is almost exactly like our 460 HP crate engine with a HP peak of 5000 rpm with a torque peak of 3,400 rpm. This type of combo will be a bit better with regard to low speed manners than either the LTD's current 460 or the 557.

The whole point with this combo is to have a street friendly RPM range and reasonably good driveability with the comp carbs 3 circuit street dominator. With the 3450+ stall convertor and 3.50 gears I expect after some tuning with a wideband that the 557 will be a blast bordering on off the hook to drive.

I intentionally left the engine a bit LEAN on the dyno to do final A/F tuning in the vehicle which IMO is more accurate. I believe there are a few more HP hiding in the combo.




S
 
#25 ·
Yes this will be added to our current list of crate engine options. I have the pieces to duplicate this combo including the 4 bolt main CJ D0VE block.

Telephone me at the contact number in my signature line or email me at: Scott@Reincarnation-automotive.com



S
 
#30 ·
#38 ·
Bob,

When using the milder ramp rates of the HR lobes and the attendant spring pressures the SR lifters have a very good service life. I've been running the comp pin oiled roller lifters in my LTD now for over 5 years and 12k miles with NO issues. It sees 6500 to 6700 rpm when needed to put the puddle jumpers and camaros in their places. lol

Keeping lash tight is critical. If the engine is not picking up lash just do regular service and keep an eye out for the unusual.

In the higher HP combos that we do for the street (700 to 850) I recommend inspection every 2 years just to be safe.


SJ
 
#39 ·
Thanks MP

I found a build on the chevelle site 496ci 10.2 comp iron heads, using hydraulic roller 243/249 .617 lift...........using solid lifters, BUT spring pressure was 220 seat and 550 open..............made 698 at 6300rpm.

He said to swap out lifters at 10-15k.

Just found it interesting on the spring pressure compared to this build.

Cheers, Bob
 
#40 ·
With the Extreme marine lobes I've been using 160 to 175 seat and 460 open. That is fine for 6000 to 6500 rpm. Pac 1940 spring on the AFR heads. Remember the 557 made 830 @ only 6,200 rpm and pulls hard to 6,500.

The springs on the 460 referenced are more like the solid roller springs for the comp EX street roller lobes. More than needed unless he is really twisting it.


SJ
 
#45 ·
Not likely as I've run .012" hot on my car. Given that the HR lobes do not have the lash ramps that a solid roller does it is best to keep lash very tight.



SJ
 
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