Discussion in ''Da Nailhead' started by ahhh65riv, Nov 15, 2006.
Erik what is your comp ratio and whats your cam specs. and thank you for all your hard work. Joe
Your welcome. My compression is around 9-1/4:1. I have A Felpro Composite gasket. I have posted this and my Cam card data in this tread.
As a reminder I am still yet to post my Dyno results from Toms Roller Tip Rockers, and the Sanderson Headers. :Brow: I will have to scan them tonight and post more!
Anxiously awaiting those, should be very valuable information!
How much does the lower compression (9:1 vs. Stock 10:1) reduce the HP results?
Are you implying that the TT roller rockers were not used in the previous posted results using the various 2x4 carb/intake set-ups? I thought you already had the TT roller rockers in the motor; were you using the stock rockers?
Yes. Toms rockers have been in the whole time... up to now.
Yes. I know I dropped maybe a couple of horsepower because I dropped the compression a fraction. There are some that will say more, and some that will say compression is overrated. I know I won't have to worry about detonation when I run pump gas. I COULD change all of that if I put in a different head gasket.
After I was finnished testing the intakes, the remaining pulls were all done with the Eelco intake manifold. In this process of putting it back on, we removed the valley pan, rocker covers, the Telesco rockers, and pushrods and install a set of factory rocker arms and used adjustable pushrods to take up the lash for the remaining tests. Here are the dyno pull sheets...
Max torque: 459.9 @ 3600 RPM
Max HP: 352.4 @ 4400 RPM
So that means to me on my engine Toms rockrs are worth roughly (max) 8 Ft-lbs of torque and 13 HP! :3gears:
For the next test I left everything as it was and we installed an air meter over the front carburetor, then we repeated the test with the meter on the rear carb. Preferably we would have had an air box to cover BOTH carbs at once to get a true air volume reading.
Now if I'm not mistaken you could theorteticaly add them both together to get your A/F ratio, CFM, calculate volumetric efficiency, etc. Obviously this method is not entirely accurate, but close.
Lastly, we pulled the Sanderson Headers off and installed the original factory 65 Riviera exhaust manifolds. The choke heat tube was removed and plugged. The manifolds were open (Blew the dyno water all over the place!ou:
I found this test very interesting, as this moved the torque lower and HP higher in the RPM range!
455.3 @ 3000 RPM (already peaked!)
347.1 HP at 4800RPM
This means the Sanderson headers are worth roughly (peak) 5 HP on my engine (with stock rockers), and up to 5 (possible) ft-lbs of torque.
This concludes my testing. I hope all of this information I have shared becomes a launching pad for inspiration for anyone considering building their nailhead. I also hope this gives some insight for so many POSSIBILITIES of new products that are yet to be developed!
Oh, and THANK YOU Joe for your recent donation!
"How much does the lower compression (9:1 vs. Stock 10:1) reduce the HP results?"
If it is like most engines a factory rating of 10 to 1 compression was never 10 to 1 in fact. It would likely have been somehere in the mid 9's. Someone like Tom may have measured this amd can nail down the figure. Generally the rule of thumb is 4% per point of compression. So if if it was 9.5 to 1 in fact from the factory, the loss on a 350hp engine being 9 to 1 is about 7 hp. With his being 9.25 in fact you are talking 3.5 hp loss on the same assumptions.
If I had known Erik, We have one here I could have loaned you. It was set up on an Offy with 2 Demons but I think it would have been close. The hat would have fit the Superflow intake.
Nice work. Thanks
Well, to tell you the truth, he did have a pretty slick box for dual carbs that was adjustable to fit different carb spacings, but unfortunately it didn't come together close enough to work on the spacing I have. Had I thought of it at the time, I would have used it on the Weiand intake as that spacing is farther apart. Then again I'm not sure how much value there would be in that now knowing the limited performance it has and the rarity of it. It would have taken a bit of fussing with it to modify it to get it to work. Craig wasn't into that.
BTW- How did you get the Demons to work on the Offy? They wouldn't fit on the Eelco.
buick said stock was 10.25:1. the two engines I had apart came out about 9.9:1. 129cc head,.015 stock head gasket and pistons were about 57 thousands in the whole.
Buick engineers were big fat liars!!!!!!!!!!:moonu:
The top of the piston has a dome that extends into the combustion chamber. How did you account for the dome volume in the calculation above?
I used 53cc which some one said on the site here.
I doubt it was the engineers- the marketing dept usually had the say about these ratings!!:laugh:
O K ; Here goes,
When engines, any engine, any company, is made there is ''manufacturing tolerances'' involved. I havent seen any engine that has perfect specs when compared to the ''blue print'' specs.
None of them will have the advertised numbers. That is what ''Blue printing'' engines was all about in the mid sixties.
You took your engine and carefully examined it and corrected the machine work to make it conform to the ''blueprint''. This resulted in an engine living a long time and putting out a bunch of horsepower. As for as Buick lying, I noticed that , for instance, the rated taxable hp for a wild cat 310 was 45, and the rated taxable hp for the wildcat 355 [the engine with a 4bbl. + 11;1 compression + dual exhausts ] was 45 hp. Putting the 64 and 65 skylarks right at the top of their drag racing class. Yup, they lied. And created a class winner.
I didn't know about taxable horsepower until you mentioned that it is in the shop manual. Thanks for the tip! I still did not know what it meant, so I looked up the definition, which explained that the concept was started in England and Europe in order to tax larger vehicle engines. By the 1960's it was an archaic concept that had almost zero relevance to engine HP performance. Here is how you calculate it:
TaxHP = Bore^2 x # cyl/2.5
for the 401NH, using 4.1875 bore, TaxHP = 56.11
for the 425NH, using 4.3125 bore, TaxHP = 59.51
These are the exact values listed in the manual.
As to why the advertised values were not in line with reality, wikipedia lists several reasons:
1) SAE standards on Gross HP ratings were very generous with pressure and temp corrections. The SAE Net HP ratings almost never met the Gross.
2) Tests were performed with blueprinted test engines under idealized conditions not meant to translate to production cars.
3) Marketing, Sales, and Production managers usually altered the test results for their own purposes.
Ok, Funk, [I wish I knew your name] Let me ''splane'' myself. When I went thru Ford School back in the 60s, they taught us that the taxable hp was the hp that was actually available to be used in moving a vehicle. IE. from the rear wheel axel flange to the ground thru the wheel. After all the running friction and power robbing accessories bled off what they used.
We were shocked at the small amount available to actually use. We were also shocked at the performance that came out of so little amount of actual usable hp.
Now, I aint no mathimitician [ heck, I cant even spell it] and I dont doubt what you say at all, but at the time that is what fomoco said that they called taxable hp, and that was their definition of it.
Either way you guys explain it, Someone was still a "Big Fat Liar" and I bet they had coodies too!!!!!p :bla:
Yeah, Yaccy, they probably did.