Horsepower Show

[bigmanjbmopar]

Today I watched them do a hemi build from Arrington Performance company with a 871 and on the dyno it only pulled 590 and 600 plus torque, the first pull was 600ho but it all seems very low, I would expect a motor like that to pull 800 easy what happened?

Watching what they did to the block and heads was about twice what I did to my 440/493. I would have thought that it would have been more hp total.

http://www.powerblocktv.com/player/show_player.php?ep_num=HP2012-05&ep_show=HP

 

[5.7 hemi]

I'm sorry, but those guys dont/shouldn't dyno any mopar engine...EVER!!!!!!!

 

[shag766]

wow, your not kidding. they had 1900 total cfm carb. my 572 build at westech performance was as close to bolt together featuring dart products on pump gas with 1250 cfm as you can get and it dynod 823hp- 737tq. where is all that fuel going they are dumping in? 40 hrs shop time on the heads and block, wowser. go figure.:confused5:

 

[bigmanjbmopar]

yeah see I'm not crazy I don't understand how or why they did? Even with the dished pistons for 9:1 it should still be in the 800 range.

They seemed happy to get barely 600 like wow this is great?! wtf? typical cheby guys I guess

 

[70rr-brian]

my 383 b block pulls those kinda numbers...

 

[Budnicks]

No boost in the blower, look at the size of the upper pulley, compared to the lower pulley, it's more than likely under-driven, probably only making 5-7 lbs. of boost "max at best", to make it last & that's only about a 150-200hp improvement over N/A on almost any combo, swap the larger size pulley to the bottom/crank & smaller to the top/blower & build some real boost, the blower probably isn't Teflon stripped either making it not as efficient as it could be, swap the camshaft to a real blower/racing app. type camshaft, but it won't be a pump gas motor any longer, but the #'s will/should raise dramatically for sure, Boosted positive displacement Roots Blower/Screw Blower engines require allot of fuel & allot of CFM to flow & work properly, {For example one of my old Blown Injected Gas engine in my old 23 Altered, old style 426 Super Stock Max Wedge with a Bird Catcher Enderle Hat on a 8:71 Mert Littlefied High Helix Roots Blower uses in the neighborhood of 3700-4000 CFM at 6800rpm (a larger Buzzard Catcher Hat is 5500-6000 CFM for larger engines or bigger blowers) & 270pgm Waternman fuel pump with 3 high speed bypasses, it could have used even more fuel, if I wanted to push it harder (6.90 @ 190mph was good at the time) & add more boost, add more High speed bypasses, different pulleys/overdrive & alter the ignition timing to retard even more under high boost or go to a much larger 10:71-12:71 Blower which I eventually did}... Also I think it was actually 690 peak HP & 650 peak TQ with a 520 HP average "through out the RPM range" & near 550-600 TQ from 2500 RPM average through out the range or something along those lines... That's my 2 cents

 

[shag766]

gas??

No boost in the blower, look at the size of the upper pulley, compared to the lower pulley, it's more than likely under-driven, probably only making 5-7 lbs. of boost "max at best", that's only about a 150-200hp improvement on almost any combo, swap the larger size pulley to the bottom/crank & smaller to the top/blower & build some real boost, swap the camshaft to a real blower/racing app. type camshaft, but it won't be a pump gas motor any longer, but the #'s will/should raise dramatically for sure... That's my 2 cents

i agree but where is 1900 cfm of gas going now.

 

[Budnicks]

i agree but where is 1900 cfm of gas going now.

Probably out the exhaust pipes, a very wet exhaust is very common on boosted engines...