Need More Power!
Thread Starter
Racer
Joined: Mar 2006
Posts: 349
Likes: 0
Need More Power!
Just looking for tips, or ideas to get all the power to the ground.
My car pulls hard from a dead stop but from a rolling start huge lack of power.
Crate 383 came with 400hp and 450torque I did some work to it after words no idea what it puts out now ( I do plain on twin turboing it in the future, but for now motor is done.)
I have Hooker side pipes with glass back mufflers. ( Will i gain more low end power by switching to reverse flow mufflers? )
I have stock TH350 trans with shift kit. ( any better trans setup to go with? )
Stock rear end ( heres my biggest issue what do i need? 4.11's? )
Car runs High 12's on a good day, I need to catch up with my friends mustang next to me :P
My car pulls hard from a dead stop but from a rolling start huge lack of power.
Crate 383 came with 400hp and 450torque I did some work to it after words no idea what it puts out now ( I do plain on twin turboing it in the future, but for now motor is done.)
I have Hooker side pipes with glass back mufflers. ( Will i gain more low end power by switching to reverse flow mufflers? )
I have stock TH350 trans with shift kit. ( any better trans setup to go with? )
Stock rear end ( heres my biggest issue what do i need? 4.11's? )
Car runs High 12's on a good day, I need to catch up with my friends mustang next to me :P
Last edited by Enersis; May 11, 2008 at 02:05 AM.
Melting Slicks
Joined: Oct 2002
Posts: 2,317
Likes: 111
From: St Louis MO
Need More Power!
You might look for your solution elsewhere. I have 3.08 gears in my '78 (not lightened at all) and ran 12.30 with 2 1/2 inch under car exhaust and DynoMax Ultraflow mufflers. With open exhaust, I ran a 12.10 uncorked. I have a TH-350 trans with a 10 inch Continental converter, which stalls at 2,800 rpm with my 406 which uses AFR 210 heads, a street roller cam, and Hooker super comp headers. Intake is a Performer RPM Q-Jet with a 800cfm Quadrajet. Short times are 1.79s and 1.80s very consistently.
I have heard from trusted sources that side exhaust will show a loss compared to free flowing under car exhaust.
I'm still thinking that your exhaust is restrictive and your torque converter is too tight.
I have heard from trusted sources that side exhaust will show a loss compared to free flowing under car exhaust.
I'm still thinking that your exhaust is restrictive and your torque converter is too tight.
Safety Car
Joined: Jun 2005
Posts: 3,841
Likes: 0
From: Inver Grove Minnesota
I think side pipes in general are restrictive for some reason. That carb seems a little small for a 383 with that much power. Did you get you numbers off of a dyno or just a estimate?
Thread Starter
Racer
Joined: Mar 2006
Posts: 349
Likes: 0
Le Mans Master
Joined: Apr 2005
Posts: 6,350
Likes: 423
From: Seattle Area WA
Glass pack inserts have plenty of pressure drop, check out the spiral inserts. The 383 will work with a 3.08, however a 3.55 is much better. I think your stall is too low as well. I had a 3.08 in my old '78 and used to run an Art Carr 3,000 with a 383. I had very similar time slips as larrywalk posted. The 3.55 swap decreased those times. Your carb seems too small as well, a 750 cfm is minimum for a 383.
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Thread Starter
Racer
Joined: Mar 2006
Posts: 349
Likes: 0
Glass pack inserts have plenty of pressure drop, check out the spiral inserts. The 383 will work with a 3.08, however a 3.55 is much better. I think your stall is too low as well. I had a 3.08 in my old '78 and used to run an Art Carr 3,000 with a 383. I had very similar time slips as larrywalk posted. The 3.55 swap decreased those times. Your carb seems too small as well, a 750 cfm is minimum for a 383.
Burning Brakes
Joined: Dec 2003
Posts: 1,004
Likes: 7
From: Adelaide South Australia
If exhaust drone isn't an issue, then go for it.
I had a very good custom stainless system system built up with an X-pipe and twin 2.5" pipes leading to a pair of free flowing magnaflows... but it droned from 1200 to 2500 rpm. Went good and hard, but drove me nuts! Couldn't live with it. (but I am an ol' grey haired fart
)removed entire system, and installed twin 2.5" system with a pair of reverse flows mufflers. Lost a few horses, but now it's a fantastic cross country cruiser.
Don't lose track of what your priorities are with your mods!
More power is great, but be aware there are tradeoffs.
Drifting
Joined: Feb 2008
Posts: 1,560
Likes: 4
From: Arlington texas
If you're happy with acceleration from a dead stop, when rolling what speed are you rolling at when you accelerate and what gear is your transmission in? The motor wasn't dynoed with that same carb was it?
Gearing would help. I'd make sure that the carb is set up properly and the tranny is dropping to a proper gear when you floor it.
Gearing would help. I'd make sure that the carb is set up properly and the tranny is dropping to a proper gear when you floor it.
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
If you run 12's on a good day and aren't happy with the performance from a rolling stop, I would definitely get the carb and trans dialed in. If you find the carb is too small/can't tune further after you are satisfied with the trans setup (if still dissatisfied after verifying proper kick-down and increased stall in converter), I'd defintely step up the CFM; 670 seems awfully low for a good breathing 383. I run a 750-cfm Q-jet on my 350 and it is built for mild performance (224hp/289tq at rear wheels). As others mentioned, your exhaust may be restrictive but if you can pull 12's on a good day, doesn't seem so restrictive to me 
Best of luck and ping us back with results!
Best of luck and ping us back with results!
Thread Starter
Racer
Joined: Mar 2006
Posts: 349
Likes: 0
not sure what carb they dynoed motor with.
but it felt like when i took off the demon 750 and switched to a 670 i gained allot of power at the start
edit: i wonder if i just tuned the demon poorly
but it felt like when i took off the demon 750 and switched to a 670 i gained allot of power at the start
edit: i wonder if i just tuned the demon poorly
Last edited by Enersis; May 14, 2008 at 06:40 PM.
Le Mans Master
Joined: Oct 2006
Posts: 7,123
Likes: 433
From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
I saw you have an auto- is the kickdown operating correctly? When you jump on the go pedal cruising down the hiway the trans drops back to 2nd gear?
Burning Brakes
Joined: May 2007
Posts: 945
Likes: 0
From: Ventura California
I run a 383 as well with a 750 cfm. I agree with others that the carb is a bit on the small side. I think I would start with a good going over on the timing, distributor curve, carb tune (follow the Lars Paper). Just my humble opinion.