Two 427s
 

Engine 1.

Blue printed .060 over L72 427, 12.2 compression, 242/242 520/520 solid lifter cam, stamped LS-6 rocker arms, stock GM 840 rectangle port heads, 2.190/1.720 valves, factory 163 intake, 4 quart factory oil pan.

Engine 2.

.060 over 427 10.3 compression, 264/264 560/560 solid lifter cam, roller rockers, ported GM oval port 781 heads, 2.190/1.880 valves, Performer RPM air gap intake, 1 inch open spacer, Moroso oil pan.


Both engines will be tested with the same Holley carb, 2 inch headers with mufflers, which one will make more power?
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Re: Two 427s
 

I will vote for the oval port motor...wilma

Re: Two 427s
 

The one with the best VOLUMETRIC EFFICIENTCY. Probably square port engine. IMO

Re: Two 427s
 

Engine 1

Re: Two 427s
 

Engine#2

Well the 870 Square port has two points more compression could add about 30HP.
The 781 Oval port has 20 degrees more duration could add about 30HP. But the oil pan is +10HP
If the 781 larger valves were machined correct. about 1.900 Bowl area and chambers deshrouded.
The Oval port Engine should take the win by about 30+ HP.

I built a 049 Oval port 454 8.5to1 compression Q jet Super Stock engine in the early 1990s and it make 660HP. The Ovals can really work, these were 2.08 1.7 255ccs.

Re: Two 427s
 

Engine #2 by 75+ HP

Re: Two 427s
 

Thanks for the replies. Engine number 1. has been tested and made 575 HP @ 6500 RPM, very impressive when you consider the factory cam specs, I could see the vacuum coming in at 16 inches at idle. I ran the the engine to 6600 and was down 1 HP, I really like the way the 427 carries the power out, this is very important to me. Engine number 2. will be tested this week, I will post the results. Its interesting todays 236 headed flattop piston Super Stock 454 makes right at 720 HP, with the 049 headed version making 740. Ken, I would be interested in where your S/S 454 peaked?

Re: Two 427s
 

Eric, you might be a little optimistic there.

Re: Two 427s
 

I was figuring on ~550 HP for engine #1 and 625+ for #2. Seeing engine #1 already made 575, I'll revise that to 50 HP. I still think #2 will make 625+. I know your 467" version makes 660+ HP and over 600 lb.ft. I'd think the 427 should be close to those HP figures with a little less torque.

Re: Two 427s
 

Idle to 6500 RPM ... #2
6500 RPM+ ... #1

SOOOOO ... #2 gets my vote for what its worth ... TAZ

Re: Two 427s
 

The carb spacer can be worth 20hp +/-.

Re: Two 427s
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Vortecpro</div><div class="ubbcode-body">
Thanks for the replies. Engine number 1. has been tested and made 575 HP @ 6500 RPM, very impressive when you consider the factory cam specs, I could see the vacuum coming in at 16 inches at idle. I ran the the engine to 6600 and was down 1 HP, I really like the way the 427 carries the power out, this is very important to me. Engine number 2. will be tested this week, I will post the results. Its interesting todays 236 headed flattop piston Super Stock 454 makes right at 720 HP, with the 049 headed version making 740. Ken, I would be interested in where your S/S 454 peaked?</div></div>

If my memory serves me right, I believe it was 6700 RPMs This was with a Comp 280 284 [email protected] 748 748 110 in@ 108 Lash IN..040 EX. .025

Re: Two 427s
 

I'd like to see the torque numbers on both engines.

Re: Two 427s
 

Here you go, not the best pull but a good average one. Engine 1.

Re: Two 427s
 

Something tells me that engine 2 will have quite a bit more area under the curve... [img]<<GRAEMLIN_URL>>/smile.gif[/img]

Re: Two 427s
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Vortecpro</div><div class="ubbcode-body">Engine 1.

Blue printed .060 over L72 427, 12.2 compression, 242/242 520/520 solid lifter cam, stamped LS-6 rocker arms, stock GM 840 rectangle port heads, 2.190/1.720 valves, factory 163 intake, 4 quart factory oil pan.

Engine 2.

.060 over 427 10.3 compression, 264/264 560/560 solid lifter cam, roller rockers, ported GM oval port 781 heads, 2.190/1.880 valves, Performer RPM air gap intake, 1 inch open spacer, Moroso oil pan.


Both engines will be tested with the same Holley carb, 2 inch headers with mufflers, which one will make more power?
__________________ </div></div>

Mark, you and I both know better. We have talked a few times and not sure if these guys realize WHO is posting!! Motor 2 has a very unfair advantage as it was out together by <span style="font-weight: bold">one of the BEST oval port engine builders in North America</span>. I just wish you were close and not over that &quot;imaginary&quot; line called A BOARDER.

What you should have done is post motor 1 against Wilson 496? That would have opened some eyes on these guys.

John (or you would know me as NPS NOVA on our &quot;other&quot; site, lol)

Re: Two 427s
 

I know who he is and what he's capable of. (That's why I picked engine #2)

Mark builds some impressive stuff. [img]<<GRAEMLIN_URL>>/biggthumpup.gif[/img]

Another bad-fast build

Like I told him over on the Chevelle forum--if I owned my own dyno, you'd likely never get me away from the damned thing.

Re: Two 427s
 

Thanks for the nice comments guys! I made a big mistake on this engine #2, I used a Icon 988 piston on this build and its a disaster, heavy, 1/16 3/16 ring pack, you need two men and a boy to turn the thing over, I really screwed up. I used that piston to get me right at 10.5 compression, I hope I don't let you down on this one, its really got me worried, I test it Friday, I will let you know then, wish me luck.

Re: Two 427s
 

Just run a step test or tweak the vapor pressure a little! LOL.

Re: Two 427s
 

Mark get up. It's Friday already, go hit the dyno. lol

John

Re: Two 427s
 

John, engine number 2 made 608 HP @ 6500 RPM, I made some mistakes on this build, and would like to try it again some time.

Re: Two 427s
 

Aside from the heavy pistons &amp; rings, what else do you think held it back?

Re: Two 427s
 

Interesting question Eric. I've been told you don't usually see gains from lightweight cranks, rods and pistons on the dyno. They do help acceleration, but are just hard to measure on the dyno. My gut feeling is there should be some freed up hp, but I don't have much experience with dynos.

My Dad's 302 sure did well with a good set of rings- so i trust there could be a couple percent gain right there. I look forward to the evaluations.

Thanks for sharing!

Re: Two 427s
 

I have seen nothing on the Dyno with light parts. But they do help in the car. They rev faster between gear changes. I think your numbers sound right. Both Very strong engines. Great job on both!

Re: Two 427s
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: KenMaisano</div><div class="ubbcode-body">Engine#2

Well the 870 Square port has two points more compression could add about 30HP.
The 781 Oval port has 20 degrees more duration could add about 30HP. But the oil pan is +10HP
If the 781 larger valves were machined correct. about 1.900 Bowl area and chambers deshrouded.
The Oval port Engine should take the win by about 30+ HP.

I built a 049 Oval port 454 8.5to1 compression Q jet Super Stock engine in the early 1990s and it make 660HP. The Ovals can really work, these were 2.08 1.7 255ccs.

</div></div>

Looks like you called it Kenny, although you were off by 3 HP [img]<<GRAEMLIN_URL>>/smile.gif[/img]

Re: Two 427s
 

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Vortecpro</div><div class="ubbcode-body">

John, engine number 2 made 608 HP @ 6500 RPM, I made some mistakes on this build, and would like to try it again some time. </div></div>

Ya Mark, your right. It's down a tad from where I thought it would be, 620/630 range, RPM is right though lol.

We have found that in some cases, the light weight &quot;rotating assembly&quot; can actually HURT a cars performance. More in these heavy streetcar type of deals. We believe the especially on the street when you not fully into it, the heavy rotating help on shift recovery??? Inertia???? i don't know for sure, but found on cars that are 3700+ this seems to happen, yet track ET's seems consistent within less then a tenth?

Funny, guys are looking at motor 2, but overlooking the fact that a stock style L72 in motor 1 made 570??????? I see a few places on that build as we know and you could easily be 630Hp, just not sure exactly how the motor went together.

Mark, good work as always.

Re: Two 427s
 

Here you go Mark:

http://i33.photobucket.com/albums/d7...ps3jlipnog.jpg

MJ horsepower with a Vintage carb, not a bad combination. [img]<<GRAEMLIN_URL>>/biggthumpup.gif[/img]

Re: Two 427s
 

Thanks Eric, thats some kind of carb!

Re: Two 427s
 

Thanks Mark. [img]<<GRAEMLIN_URL>>/beers.gif[/img]

I heard a little hiccup at the hit to WOT, might need a little heavier secondary spring.

Test, tweak, test again, tweak some more...all in a days work. [img]<<GRAEMLIN_URL>>/biggthumpup.gif[/img]

Re: Two 427s
 

`wdj<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: VintageMusclecar</div><div class="ubbcode-body">

Like I told him over on the Chevelle forum--if I owned my own dyno, you'd likely never get me away from the damned thing. </div></div>
I can't dream up a better circumstance... well if you want to throw in even a 1/4 scale Wind tunnel I'd take that as well. [img]<<GRAEMLIN_URL>>/3gears.gif[/img]

Re: Two 427s
 

is engine 1 with rectangular port a closed chamber at 108cc chamber.If the chamber was 122cc like the oval ports do you think power levels would be any different on that comparison. Thanks marc.