Motor geeks only
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
you also might wanna shut off the fans for the dyno pull.. They are causing more resistance to the alternator. It's not as much resistence as the mechanical fan, but it still costs you HP...
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Originally Posted by Solid LT1
Dem is sum BIG AZZED size intake ports you have on your motor there! I wouldn't run those on a street/strip 406 let alone a 383. You should put a RPM air-gap intake on to compensate for going too large on your intake ports in my opinion. Then again what do I know, my 170cc intake runner 355 LT-1 only runs 12.28@117MPH with 371 RWHP on a Dyno-Jet.
I always thought that it was a great running motor for only 383 ci. I did use a smaller carb and single plane plenum than the poster.
You can't run an intake with smaller ports than the heads - You have to have ever decreasing port size clear to the valve.
Last edited by gkull; Jul 23, 2005 at 12:37 AM.
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
I sure am dying to see some ET's for some of these motors out there! Maybe I need to photo mine but it has run a best of 12.28@117MPH using a 650CFM #4777 Holley and "stock" LT-1 intake. I'm sure the experts will tell me I need at least a 750CFM carb but, when I tried my bigger Holley's (I have several) the 60ft times went to heck and besides, I autocross my LT-1 so bottom end pull/response is important to me. I know my combination works, I am lucky, my best friend owns an Automotive Machine Shop, and another friend is an engine builder for USAC Midgets and Silver Crown cars, his Mopar 4 cylinder motors are some of the nations fastest Midgets. 8 years ago when we dynoed my Vette's 355cu/in LT-1 on his Depac equipped dyno (Depac is the choice of most Nextel Cup shops that have to actually pay for their equipment) he complimented me on a job well done. You guys build your motors the way you want to and I'll do mine my way and maybe someday we will meet at the racetrack, to decide who is best, I'm happy with my combinations that I build and many people are impressed by their performance. 
Last edited by Solid LT1; Jul 22, 2005 at 11:01 PM.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,445
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
LT1 - I tried a 825 Race Demon with my setup and went back to the 750 Speed Demon. I really think like you a 650 speed demon would have really given better responce and still been within a few HP on top. Where you never drive anyway. 
That is another point of why i went with the Team-G smaller intake plenum size. I didn't need a Super Victor for 4500-8500. The Team -G's come in 7200 or 7800 rpm
That is another point of why i went with the Team-G smaller intake plenum size. I didn't need a Super Victor for 4500-8500. The Team -G's come in 7200 or 7800 rpm
