The "Sneaky 500 HP" motor

Here is the 494 SA from when I first built it. Chris

 

Chris, PC decal came from Dwayne Heckmann. Jim may have soem though.

Everyone else, thanks for your comments. I am really looking forward to getting this thing on the road. Body is just about ready for color. Things go slow when you only work weekends on it.

 

Hey Jim,

Reading all this with interest.

Besides the obvious (extra work on the intake, different cam), how does this engine stack up against the one in the Electra? We never discussed things like static/dynamic compression; I am intrigued, and the board might also have interest in the comparison, as my engine also runs a whimpy ('70 Riviera)cam.

 

How is the torque down lower like at 2000 RPM?

 

Hey Chris..

Those are some excellent iron head numbers..

Funny you should mention Dwane's carb, that's it in the picture.. I finished it here last week, but hung onto it because I wanted to test a stock idle circuit on this engine.. it performed very well, and guided me as to how much to modify the one that goes with this engine. It shipped earlier today.

As John mentioned, he supplied me with that valve cover decal, only one is used on the LH valve cover, as pictured. You will have to get one from Duane.

Thx

JW

 

Steve,

Your motor is the polar opposite of this one, when it comes to cam and dynamic compression.. your cam specs are .380 lift/ 200*duration at .050. Your engine is a high cylinder pressure motor, designed for good low speed torque, and that perfect idle quality. Even with your 9.6 static compression, your Dynamic is up over 8-1. You have a very short duration, tight lobe center cam.. and the cylinder pressure it makes, while being useful in getting the big boat going (making torque just off idle) that cylinder pressure (and the 2.73 rear and 5600 lbs) is why we have had to play with the advance curve to resist that part throttle detonation. We experience very high engine loads with your build. Something you don't see with a 3800 lbs GS, with a 3200 stall converter and 3.42 gears.


It is possible that a variation of a cam along these lines could be used in your car, and is the reasonable alternative for a change to make, if and when you want more than the 420 HP you currently have.

As a point of review, here is Steve's buildup.

462 TRW Forged piston shortblock
Q-jet
Stock 70 SF engine cam (.380 lift, .200/210 duration@.050) 110 LC installed at 106*
TA SE STG 1 heads, 317/230@ .500
Performer intake- port matched
TA Shorty headers
OE Hei ignition
Here is Steve's dyno sheet..



9.6-1 compression, 8-1 Dyn Comp, Ported Perfmer/ 800 cfm Q-jet, TA SE Heads, headers
Small, tight lobe center cam- Perfect idle

And John's again



10.25-1 compression, 6.5-1 dyn comp, Ported iron/800 Q-jet/TA SE heads/headers
Moderate size wide lobe center cam- Very mild lope idle

And now let's reach back into the archives, and look at the prototype Level 2A motor, which has the same heads as Steve and John's engines. Same cam as John's but this is ground on the more traditional 112*LC version.



10.6-1 Comp, 7.8 dyn comp, Ported single plane Intake/1000 cfm carb/TA SE heads/headers

Moderate size tight lobe center cam- Max lope to run the brakes

Now, the last sheet is a no compromise airflow engine.. It has a very ported KB cool Runner intake, and a 1000 cfm carb. But the heads, cam (except for lobe center) and fundamentally the shortblocks are the same between this engine and John's. The 470 shortblock I have come up with is really about cost effectiveness in building the engine, resulting in a strong engine at a lower price, than was previously available with off the shelf parts. The 470 and 464 are about "a horse apiece" when it comes to power..

But the point here is that the first two engines that are very similar, when it comes to the shortblock, almost identical heads and headers, the variable is camshaft . In the last engine, airflow restrictions of a dual plane engine are eliminated, with the big single plane manifold, and the big carb. I included it, because it's an interesting study of the affects of cylinder pressure, due to DC and complete cylinder filling.

What conclusions can we draw?

First, the engine is fundamentally an air pump. The better the pump (as witnessed by the VE number) the stronger the engine, in it's optimal operating range. Last part of the statement is very important to understand.

Let's look at torque production between the first two.. At low rpm, they are nearly identical, although if we had 2000 rpm numbers, Steve's engine would be the star. Very short duration, very strong off idle engine, well suited to a big heavy car with hwy gears. Get's 16mpg. Lovely engine to drive every day.

But.. the small cam makes the motor no where near the air pump that John's is. Holding the valve open longer, and lifting it higher, results in an 80 HP increase. While not optimal due to dynamic compression compromise, this is a very nice engine to run with in a GS, on a daily basis. Better suited to the 3.42 gears and 3200 stall converter and 3800 lbs of a GS.

The comparison to from Steve's motor, to the Level 2A, is night and day difference.. The 2A is an excellent air pump, but it's constrained to a higher, narrower rpm range. It's considerably weaker at lower rpm. In a very hot, limited use street car, it's the hot ticket. The 3700 lbs, 3.9 geared 87 Regal that this motor went into has run in the mid 10's.

But wow, talk about idle quality difference. You pay dearly for that 160 HP. A 4 corner idle Holley and lots of initial advance are required to run vacuum brakes, and if you were to put a tight converter in behind a 2A engine, it would feel pretty lazy until you got up to about 3000 rpm.

And the 2A scares the little ol' ladies off the bus bench when it rolls up.. your not going to fool anyone with this engine. It's hot, and everyone that hears it, knows that.

Comparing John's to the 2A is less of a difference certainly, but the real difference doesn't really show up on the dyno sheet..while it gives up 80 HP and 50 ft/lbs, it's a more versatile engine overall, with a broad power range. The difference is also idle quality and sound of the engine, thru the exhaust. The 2A is hairy, there is no doubt about that, and it's a great piece with big exhaust on it, when your looking to impress your buddies, and intimidate the bow tie in the other lane.

John's engine is "Sneaky HP", hence the thread title. It really sounds like a STG 1 that needs a bit of a tune up. Idle up next to that bow tie, and he's gonna figure he's going to eat you alive..

until the light changes.. :laugh:


Performance Street BBB engine building is an ongoing evolution for me. I am getting closer every day to that 600 HP street engine, that runs on pump gas, looks stock, sounds mild, but tears your head off. And at the same time, it's easy to live with. I think in the future, the Big inch alum block motors, with the right roller cam and heads, are going to be the ultimate "sleeper" engines.

Along the way we will evaluate big inch true Stock appearing engines, and I am going to build a 11.5-1 compression version of John's engine for myself.. to prove that you can run that compression on pump gas, day in and day out. I believe that motor will make around 540 HP. But that's something I have to use myself for as the Guinea pig, as I try not to get too far "off the grid" with these customer engines.

JW

 

JW,

I love the fact that not only are you trying these things but you're into it!
I can't wait to start on my engine and see what we can come up with. I know the car is light so if we can make some good "stock appearing" power we'll be turning some heads at the track!!!

Keep up the good work. The more tricks you can figure out the better!!!!

 

JW,

VERY interesting! So if I'm keeping up, what's going on is that you're using a bigger cam with wider lobe centers (which if all else was equal would reduce overlap), but more duration and lift (which brings the overlap back where it was with the "smaller" cam), and this gives you:

1. More hp - due to better breathing and decent overlap
2. Good idle - due to the wide lobe centers
3. The ability to run lower octane fuel - due to the "bled-off" compression of the "bigger" cam.

Is that the basics?

 

Thank you John, we will get a couple ordered up. Have fun with your new engine, it looks great and made even better #s. Nice work Jim.....Chris

 

Jim, carb looks great. Can't wait to get it. I got a e-mail from Dwane a couple days ago and the heading was GONE FISHING! :laugh: so he is gone for 2 weeks. Did you send it to me or Dwane?
I'm interested to see more of these SA type builds on the dyno, thank you for the great thread.
Will John be using a stock fuel system with a pusher pump with this engine? I know on the SA 494 that I did the stage one pump with a good pusher pump fell very short of keeping the little fuel bowl full in the Q-jet. I would of loved to see the effects of ported exhaust manifolds compared to the headers on John's engine just for kicks. Have you tried playing with the secondary throttle plates on the dyno or do you stay with the factory spec's? I have more pics of the intake on this 494 but this is all I could find right now. I am also looking into getting the already ported intake and exhaust manifolds sent for some extrude honeing and I'm thinking of trying the place in the link. Do you having any input into extrude honeing? I love this SA stuff it would be nice to keep this thread going, and it looks to me that you do also. Thanks Jim......... Chris http://www.extrudehone.com/contract_service.php

 

Chris,
I was planning on just using the stock lines and Stage 1 mechanical fuel pump. Do you and Jim think I need more?
John

 

Depends on what your going to do with it John... If your just going to go street cruising, with the occassional 2-3 gear blast, it will be fine.. If you going racing a lot, then yes, you will need a pusher pump, to fully fuel the beast all the way down the track.

About 475 HP is the practical limit of the STG 1 fuel pump, to insure continuous delivery of fuel all the way down the track, or for extended street full throttle operation.



JW

PS. Chris, carb is on the way to you...

 

Yes, your correct, although I won't make assumption number 3 quite yet..

What I am seeing is a motor that builds power across a broader range, and to a higher level, than with the smaller camshaft. Yet retains the same, or better idle quality.

JW

 

I'm thinking a sumped pump would be an excellent choice for your ride John. This would help keep it quiet while giving the needed supply under all conditions.

Jim, I bet you've done this before?

The Mallory 140 is a quiet pump but not totally sneaky.

 

After re-reading this, I'm wondering how suited to a heavy car this setup would be. Seems like JW's comments comparing this to Steve's and the Level2 engines indicate that this engine wouldn't pull a heavy car off the line very well - or maybe as well as a 'smaller' cam. Is that correct?

 

Hello All,
This thread is really cool, and I'm amazed at the results of these different combos! Looking forward to see the upcoming builds, and I guess I should disclose that my engine is the 2nd or 3rd in the hopper-
(Unless some other knucklehead is talking JW into an Offy Dual Quad equipped, iron-headed motor with exhaust manifolds!!ou
I'll attached a few pics of the car it's going in-
From 1988 or so.....
The car has aged much better than the owner!
Thanks JW for the entertainment here and keep the updates coming as they materialize-
Jerry

 

Depends...

You certainly would not want a 2A motor for this application, for the normal cruise/light race big car.. way too hairy..

Steve's motor was built to be an everyday driver, in 4 door 75 Electra, with all the options, and a 2.73 gear, big 13" converter.. so off idle/mid range performance and mileage were the goals here.

This would be a good build for a full size car, used for light to moderate street action and the occasional strip blast, with the correct converter and 3 series rear gears.

JW

 

Yup, that would be you Jerry...

We will be talking next week about a cam for your combo.

JW

 

Interesting build. I think our 455 with the 52241 Crower and 8:1 cr might have some similar qualities though a little more static compression probably wouldn't hurt us any. Good to see this approach is working out!

Jim B

 

Jim, you never answered me when I asked how the torque was in the 2000 RPM range. I would assume that would be important for being able to cruise around without a ridiculously loose converter or a bunch of downshifting.