[flink69SS]

So after a morning at the speed shop I have my chasis dyno #'s.
Max TORQUE = 429.9 @ 4,500 RPM
Max HP = 394.3 between 5,200-5,800 RPM's.
HP wasn't falling off yet @ 5,800. This is with an M20/ 3.31 gears spinning the speedo @ 139mph.
Question: What is or IS there a single factor that is keeping my hp lower then I'd expected or is this combe built accordingly?

It's a Mark IV 468 with: Steel Crank, stock rods with ARP bolts, Keith Black Hypereutectic domed pistons @10.25:1 comp,1.7 Pro Magnum Roller Rockers, Hydrolic Roller Cam232/232 @.050/ 578*, Pro Magnum Hydrolic Roller Lifters. The heads are heavily Ported 99cc's, 702's with 2.19/1.88" Manley Valves, comp springs and Titanium Retainers. Wieand Team G Intake with a Quick Fuel 850 DP, HEI ignition and Hooker Comp. Headers with 1 7/8 pipes and a 3 1/2 collector.

Am I missing something or is this what it is?

 

[Tom Mobley]

394 x 1.2 = 473

might be a little light for what you've got there. what do the timing and A/F ratio numbers look like? Did the guys have a wideband O2 meter hooked up?

does the car pull hard thru the top of second and the top of third on the road? Or track, as it may be? Got any nose-over effect at all?

got a decent fuel pressure gauge hooked up where you can see it on the top end?

 

[flink69SS]

A/F mixture was 13 at WOT. Total advance is 36*. Pulls like a mad dog through the top of 2nd and 3rd. I do not know what nose over means.

 

[BillK]

Frank,

I think a lot of people read a lot of magazine articles and expect a lot more than they should out of thier engines. If yours is making almost 400 at the rear wheels, I figure like Tom that you are probably around 475-480 at the flywheel .... not bad in my opinion for your combination.

The cam is a little small, I am doing a 468 for one of my part time guys and we are using a .630 lift hydraulic roller. Edelbrock heads, otherwise about the same. 10.5 to 1. If we ever get it finished, it is going on the engine dyno, and then I will talk him into the chassis dyno and we will see what the difference is. I am going to be very happy if we see 525 or so at the flywheel.

Do you have mufflers on it ?

 

[flink69SS]

Bill- Yes, Flowmaster 40 series. It's a street car...

 

[Wolfplace]

I think a lot of people read a lot of magazine articles and expect a lot more than they should out of thier engines.

I could not agree more :thumbsup:


There could be a little more with some tweeking but these look like real world realistic numbers for a pretty mild build & depending on air cleaner, exhaust etc. could easily be 500 corrected on an HONEST ENGINE DYNO with a more optimum environment
Here is an older post with a few honest examples:

I like to call these GM crate engines my "reality check" engines,,,
http://www.chevelles.com/forums/showthread.php?t=139446&page=2


Now here is what can be done with a 454 without too much trouble & this is a street engine.
469, (4.320x4) 11.0 compression, Brodix RR Rect heads with CNC chamber, T&D 1.7/1.7 shaft rockers, Ede Victor with Pro System's Dominator, 2" dyno header w/3.5" collector to 6" exhaust, fuel was 50/50 91pump & Phillips 110
Custom Comp cam 254/262, .703 lift, 110 sep, 106 ICL (this cam rocks,,,,)
Here are the numbers
RPM CHP CTRQ
3300 275 438
3500 302 453.5
4000 385 506
4500 476 555
4800 512 560.4 PK TQ
5000 529 556
5500 585 559
6000 618 541
6500 656 530
6900 685 529 PK PWR
7000 682 522
==================
Here is something closer to yours except for the inches,

Pretty simple basic bolt together deal, 489, Ede 60459 roval heads, Ede 5062 cam .527/.553, 224/232, 114 lsa, 109 icl. I believe it's called the Torker Plus, RPM intake, 1413 800cfm Ede carb, Probe rotating assembly.
Carb was great at part throttle like hi 13's, low 14's & pig rich under power like 10.5 - 11.4 (AFR)
Timing was 36 degrees, 10.8 compression
numbers were:
2800 - 267 - 501
3000 - 306 - 519
3500 - 359 - 538
4000 - 427 - 547
4500 - 460 - 538
5000 - 480 - 514
5500 - 478 - 456
I can see an easy 20-40HP here with some basic tuning

The compression was higher than planned but the parts were as supplied & I just supplied the machine work & dyno time along with profiling the cam & flowing the heads etc.
Cam was advertised as 302/304 but measured a surprising 285/288 at .006. The rest of the numbers were right on.
=========
It was redynoed with the same Ede "Torker plus" cam & the Brodix RR, Brodix intake & HP 1000 carb after this & made about 520 HP.
Compression was a point less due to the head change (110 to 118cc)
==============
Again, redynoed with the addition of a "few" changes, this is the exact same engine as above again with almost a point less compression

489, 10.0 compression, 36 degrees timing, 91 octane.
Isky R582/R548, 284/294, 252/260, .680/.680
Brodix 290cc Rect RaceRites
Brodix 2016 modified dual plane intake
Holley HP 1000
2" dyno headers
RPM HP Torque
3100 315 533
3500 369 553
4000 440 577
4500 511 596
5000 561 589
5500 599 572
6000 613 536
6500 602 486

Peak power 614 @ 6200
Peak torque 597 @ 4600