625 HP with the torque of a stocker at 3000 rpm

Hi folks,

I do a lot of buildups that are very similar.. ie as much hp as possible with the upgraded STG 1/2 SE heads, with vacuum to run the brakes ect ect..

Occasionally, I run across someone willing to use a vacuum pump, or has manual brakes which opens up our cam choice a little more..

A while back we did a little testing on a STG 1 SE alum motor, with compression ratios vs camshafts... and went a little bit away from the "norm".. such as using a big solid on a 10 1/2 to 1 street motor, and we were surprised by the results.

That motor ended up making 598 HP with a 308 cam and a B4B dual plane manifold.

With that experience under out belt, I decided that we should go full tilt with the heavy breathing equipment on the next one and study the effects of long cam duration/relatively low compression ratio/big intake and carb.. and really see what it does to the torque numbers down low.

Let's challenge "conventional wisdom"..

A customer with a 4 speed GS w/ 4.10 gears came along, and I thought this to be the perfect candidate.

Here's the buildup:

76 Block w/TA gridle
SRE Oil pan
TA front cover assembly
Ported STG 2 SE heads - 320/260 cfm
Ported KB cool runner intake (TA SPX the same)
1.65 TA roller rockers
1000 cfm HP Holley
TA Conical Dish pistons/ Billet con rods
TA 308S cam, installed at 103* intake centerline- I purposely advanced the cam 5* to work with it's pump gas friendly 10.66-1 compression.

TA 2" STG 2 2014 headers (long tube)

One thing to note with the cam was that it had a bit of variation from the advertised specs- it was 270* on the intake duration @ .050, and only 266* on the exhaust.. but with great exhaust flow the the STG 2 heads, I was not the least bit worried about that. I have held for some time now, that there is no longer a need for the split duration of an alum head engine's camshaft, favoring the exhaust, and this is yet another example of why I believe that.

Now, I have tested many Stock 1970 STG 1 455's in the past, all of them have made between 370 and 385 HP, but not one of them has surpased 465 ft/lbs of torque. We always have attributed that difference from the factory rating as possibly just a difference in the dyno's of the 60's, vs the 2 year old Superflow 902 we use. And maybe yet I will see one actually surpass that number, but it has not happened yet.

Anyway, on the last pull on this engine, after it was all tuned up, we pulled it from 3000 rpm, to study the effects of what some would call a mis-match in components (too big a cam for the compression, too big of an intake and carb to make any low end torque ect..)

Keep in mind, the highest torque this dyno had measured on a stock 1970 455 STG 1 engine is 465 ft lbs at 2800 rpm.

And to boot, this motor would idle at 750 rpm.. Love those 1000 HP's..

JW

 

While it dips just a bit after 3000 rpm, we are still within 30 ft lbs of what I have seen a stocker make, and maybe only 2-500 rpm higher.

And anyone who has ever driven a modified GS knows that when your on it for power, the motor will never see the low side of 4000 rpm while your foot is in it, after it pulls thru it in first gear.

And in this car, with a rock crusher muncie and a 4.10 gear, it will never see it.

While I will advise my customer to pull the stick at 6500 rpm, I would have no problem running this motor to 7K thru the traps.. it's built for it, and it does not lay down.

Always more options out there, and I share this with you guys to illustrate the point.. don't be afraid to try something "unconventional" if you have the right car to put it in.


PS.. running cool water under the intake, and cooling it to around 90*, would pick up another 10 HP and Ft/bs.. we have tested that too.. :TU:

JW

 

Hi Jim,

Interesting dyno work!!! About 8 to 10 yrs ago Gary Kubisch ran a 308s in his 430 with semi ported Stg 1 iron heads and 10:1 compression with a cast intake. If my memory is correct the car ran into the 11s.

This kinda proves that if your going to pick a camshaft its better to have a camshaft that is too large vs. too small. I would be willing to bet that the cranking compression on this engine would be nice and low also which is much easier on the bearings.

Could the TQ numbers down low be effected by the 15:1 air fuel ratio?

Anyhow.. nice work!! I love to read these dyno result threads. Lots of great information. Thanks for sharing!!!


Take Care

 

what jets and pv's are in that 1000 carb??

thanx

 

John,

That first number on the sheet is influenced by the engine being in a static rpm state for several seconds before the test begins, so we always throw the first couple Air/Fuel numbers out.. come up a couple hundred rpm and your seeing what the carb really is doing in an acceleration test. It had leaned out a touch here due to the HVP spacer used in this test, and we could have probable coaxed a couple more numbers out of it with a couple jet sizes, but at some point you just get into dyno racing.. and I try not to go there.

If you have never seen an engine like this at full throttle, pulled tight on the water brake at 3000rpm, your missing out.. it's quite a sound to experience. This is by far the most strain the engine will ever endure, as there is absolutely no slippage, as the flywheel is bolted right to the water brake, with no torque converter to absorb energy, or tires to spin. I will generally only do this on an engine that has some saftey margin built into the hard parts, and this one with a real thick block, the girdle and billet rods has that at this HP level. I have built a couple of engines that far exceed the output of this motor, with basically the same hard parts in the bottom end. We pulled a 706 HP STG 1 TE/flat tappet Super Gas motor off the dyno a few months back, with the same stuff. Sweesy's 815 HP motor is the same, except of course he has a billet crank.

JW

 

Jim,

Box stock.. never even had a fuel bowl off it..

84 square with 6.5 valves

In actual use, no spacer will be used and you can see the box stock 1000 is right there with the A/F ratio.

 

Sheesh.....I did not know Mike at TA was making a gridle :laugh:

Is he trying to compete with the George Foreman Grille????? :Brow: :Brow:

Couldn't let that one slip JW...I needed a good laugh.......are you staying warm in the sub-freezing temps in Minne-snow-ta??? :Brow: :Brow:

 

Love to chat George, but I am out back frying pancakes on a girdle.. :grin:

 

Jim, thanks for building my motor, um, I mean one like it. I'm slowly building a 464 with identical parts except sportsman rods, the 304S cam which is 268/268 duration and I must use shorty headers for the lowered road race chassis. I also have a 1000 HP but on an SP1 and plan on a dry sump which is holding me up right now. Read money. How much do you think the shorty headers will hurt it? I,m hoping to use pump gas with the 10.6 cr. This is getting me fired up again!

 

Paul,

About 8-12 numbers less, HP and TQ, at the peak, and at the averages is what we have seen between the shorties and the full headers.

JW

 

Thanks Jim!!

Thanks for all of your hard work and expertise on this engine project. I'm really looking forward to getting the '70 Stage One back on the road. It's been in the garage less engine since 1997!
I'm suprised no one has goofed on the choice of the manual trans!
By the way, it won't be any old Muncie behind it....It will be a new Jericho DR4, same as Nascar & super stock drag cars use.
Thanks to everyone on this board who makes it such an awesome resource. The Buick guys are the best of the best out there. :3gears: :TU:

Jerry Shumard

 

lil more head lil less cam

I did a motor for Tod Miller in 2003 doing the same thing..to much of everythig 'cept compression.the result was 665 HP 615 Tq.

Cam was 260 / 266 @108 4deg adv.
TA T/E flowed 350/284 @ .600
2" headers 10.5 :1 pump gas

I believe Tod got his car in the 9s on pump gas with this motor
Dyno run with 1250 dominator...Tod ran a 950 hp holley which lost 9 hp/9 tq avg.

Sorry i coudn't attach the scanned dyno sheet copy, but here are the numbers


rpm tq hp corrected
3900 558 414
4000 569 433
4100 581 453
4200 590 472
4300 595 487
4400 603 505
4500 618 542
4700 616 551
4800 623 569
4900 621 579
5000 620 590
5100 617 599
5200 615 609
5300 611 616
5400 607 624
5500 602 631
5600 599 639
5700 592 643
5800 587 648
5900 579 640
6000 574 655
6100 568 660
6200 562 665
6300 554 665

:beer , Dan Hopkins

 

Jim, What was the manifold vacuum on this engine at idle???

 

jim how do you think a 76 455 with 68 430 heads, sp1 intake, and a ta288-92h cam would work the car is a 4 speed and i can change gears if needed but was wanting to run 3.55's the pistons are stock comp. but new. i know i really need to find some used higher comp. pistons. but im saving for the aluminum heads right now (and head gaskets for my duramax now)
Thanks
Ross

 

Andy,

A 308 cam makes about 5-7" of vacuum at idle.. so an auxilery vaccuum pump is required.

Ross,

That combo should work just fine, watch your deck height with the pistons, there is a full point of compression to be gained generally by going to zero deck.

And Dan's motor is a good study in what heads will do for you.. Dan had fully ported STG 2 TE's I believe on that motor, whereas the ones on this motor were mildy ported SE's. Dan was able to run a smaller cam, and the bigger SP-2 manifold, and make more power.. I was at that dyno session, and after Todd sold the car, that motor ended up here for a few changes to suit the needs of the new owner a bit, although it was a rush job, and we did not have a chance to dyno it again.

JW

 

What are the oiling mods done to this engine? I'm copying this build and there are too many options for oiling mods. o No: Also, is it safe to resurface the front of the block where the timing cover bolts on? If so, whats the max amount of material that can be removed?

 

Andy

Be careful surfacing the face of the block.. what's wrong with it?

Oil mods on all Level 1a and 2a motors are as follows

• 5/8 pickup and 5/8 oil passage on the suction side
• Oil pump and filter housing ported (or TA assembly)
• Oil feed hole from pump to block champhered and oblonged slightly
• Main feed from the pump to the LH galley drilled to 1/2"
• small passage from the oil feed hole to the RH main galley champhered and smoothed, front half of the RH galley smoothed and champhered
• #2,3,4 main bearing feeds drilled to 11/32
• All oil holes in main feed champhered for bearing oil hole alignment
• Main bearing clearance targeted at .0025 +- .0002
• Rod bearing clearance targeted at .0027 +- .0002
• TA adjustable oil pressure regulator, set to 65-75 psi at 5000 rpm
• Main galleys plugged with TA threaded teflon plugs (front)

 

Thanks a lot Jim. I read about oiling mods for hours on here but wasn't sure which ones applied to this particular build. I thought a lot about cutting grooves in the bearing saddles and the front to rear equalizer line.

I attached a pic of the area of concern on the front of the block. It's the small gouges to the right of the oil feed hole. I did this while removing the stubborn 37 year old timing cover. The gears had the nylon teeth so I'm pretty sure that cover was never taken off. I suppose I could just clean up that area and the cover will conform to it but I wanted to ask about resurfacing.

Also, there seems to be some pages missing on the TSP site in the Mains section.

 

im right on par with that (practically) all except the clearances.

Im expecting a bit more power too, my clearances are .002 on all except rear main is .0025 (front is measured at that too, but im going to recheck with a new bearing)

should i have had them bigger?

 

Hey Jim a little off thread when you dyno motors what is one point of comp in HP worth say 9.6to1 to 10.6to1 thanks for all the great info.