1/4 Mile Issues

clement · Nov 17, 2013

i wasn't trying to insult you with the world is flat comment. so im sorry about that.

A5literMan · Nov 17, 2013

Very interesting discussion.

NIKwoaC · Nov 18, 2013

clement said:
ive seen people with over 580rwhp at 3400lbs only go mid 11s if you want to talk about under achievers.

336 to the tire and I've barely cracked 12s.

Because street car...?

clement · Nov 18, 2013

with your car I would expect to see 115+ mph with that kind of power assuming its 3200lbs or so. could be something as simple as how the valvesprings are setup. a couple little simple things can kill an NA car. its tough to shake it down away from the track. 110mph is good for 12.20s though.

JD1964 · Nov 18, 2013

clement said:
i wasn't trying to insult you with the world is flat comment. so im sorry about that.

I took the "world is flat" comment as playful banter. There is no need to apologize. It's all good.

NIKwoaC · Nov 18, 2013

clement said:
with your car I would expect to see 115+ mph with that kind of power assuming its 3200lbs or so. could be something as simple as how the valvesprings are setup. a couple little simple things can kill an NA car. its tough to shake it down away from the track. 110mph is good for 12.20s though.

Yea, I think there is a lot that I’m leaving on the table with the car. The car should be getting a new transmission this winter that will better handle the power, and if money permits, new lightweight wheels to replace the 28 lb replica Mach 1s. Then I’m going to track the crap out of the car next season and see if I can’t post some better times/speeds.

84Ttop · Nov 18, 2013

No useful input, Just going to eat my popcorn and watch the show

A5literMan · Nov 19, 2013

NIKwoaC said:
Yea, I think there is a lot that I’m leaving on the table with the car. The car should be getting a new transmission this winter that will better handle the power, and if money permits, new lightweight wheels to replace the 28 lb replica Mach 1s. Then I’m going to track the crap out of the car next season and see if I can’t post some better times/speeds.

Looking forward to seeing that!! You definitely have the power for better times.

sharp2377 · Nov 28, 2013

clement said:
its all about booster signal. that combo would probably run fine with a dominator, it has so much signal its crazy. if it were mine I would put a vic jr and a good 750 4150 like a quickfuel or AED and watch it go 11s. we had issues with three holley 4150s with a 10:1 358" Cleveland headed Windsor with a decent restrictor intake and a decent sized flat tappet cam. it wouldn't even run right with a new 650HP. the 650HP, a good known 750 HP, and an 830 that ran good on a 347 with small heads all had a stumble out of the hole on the secondary side. all these carbs went 7.30s@95 in the 1/8th. then we unhooked the secondaries on the 830 and the stumble went away. the car went 7.20s@93 like that. then we bolted on my AED 750 HO modified, adjusted the idle and made sure everything was adjusted correctly. the car went a 6.88@98mph with it setup the same as it came out of the box from summit. so there is a little more to carbs than just having the 'right' cfm rating.

im gonna have to disagree with ya. its about finding the right size based on displacement, induction cross section, compression, camshaft, vehicle weight, gearing, and converter.

http://www.aedperformance.com/tuning-tips.html

I think a vic jr I

sharp2377 · Nov 28, 2013

I think a vic jr is a bit much on a mild 351w, don't you think? I actually just ordered a rpm air gap and worried about that being too much. I was told by summit that a 600cfm carb was more than enough for my setup and that a 750 could actually make less power for me and should only be used on big hp motors. I haven't tried other brands of carbs on this motor but I really like the summit carb. I just touch the ignition and it fires right up, no hesitation, plugs read perfectly, and idles good. I eould hate to switch gor a couple of HPs and then have nothing but problems. Thank you all for the input!

Bullitt347 · Nov 30, 2013

You can never have too big of a carb. If adjusted correctly you could put a 1100 cfm Dominator on that 351 with no issues. It is like saying you can't put a 90mm throttle body on a 90' 5.0 and get it to run right. Hell diesel engines do not even have a throttle body, just a big open plenum, and they typically do not spin over 4,000 rpm, and spend most of the time under 2,500 rpm. I can get a stock 302 to idle and drive great with a 1bbl carb, or with a 1100 cfm Dominator, it is all about proper adjustments, and BTW the 1100 cfm equipped engine adjusted correctly will ALWAYS make more power over any other smaller carb, period. Personally I would get a Quick Fuel 780 SS series carb and watch that thing fly. Dominators cost to much for this application.

JD1964 · Nov 30, 2013

Fuel atomization begins at the point where the air enters the throttle bore on the carbureted engines. That's why velocity is important. On the diesel and fuel injected examples you give, the atomization happens way down in the intake where the runners neck down and there is increased velocity at that point. Comparing carburetors to your examples is apples to oranges.

I disagree that a bigger carb will always make more power. It's about getting the fuel mixture correct. If a carb is big enough to pass the amount of air an engine can pull in, it's big enough. From that point, it's a matter of getting the fuel mixture correct.

Again, a larger opening will not enable an engine to increase it's fixed ability. So long as a bore is big enough, putting a larger one on will not bring in more air volume. No way, no how.

mikestang63 · Nov 30, 2013

Doesn't matter IMO how big a carb or TB on a motor. It's only going to flow as much as the intake/heads are going to allow it. You can slap on a dominator carb on a stock 302 with E7s and it is not going to make more power than a 600 holley, just as if you put a 90MM tb vs. a 65MM.

A5literMan · Nov 30, 2013

And I thought this debate was over

NIKwoaC · Nov 30, 2013

mikestang63 said:
Doesn't matter IMO how big a carb or TB on a motor. It's only going to flow as much as the intake/heads are going to allow it. You can slap on a dominator carb on a stock 302 with E7s and it is not going to make more power than a 600 holley, just as if you put a 90MM tb vs. a 65MM.

Agreed, but there is also flawed logic in "good enough" parts sizing. Some stuff, like TBs, there is no harm on being a little on the big side. If you set out to make 300 RWHP and you buy a "400 RWHP" TB and you end up making 310 RWHP, are you or anyone else going to complain?

Carbs on the other hand... I have no idea about those caveman things. That's voodoo magic to me.

JD1964 · Dec 1, 2013

It's not complicated really. Its basic physics. It all comes down to air / fuel mixture. Remember, the thread was started about a carburated naturally aspirated engine. The engine is a basic air pump. It can pump in a certain amount of air. The amount is limited by the engine displacement and the max rpm the engine is expected to run. The CFM requirement can be calculated and a carburetor size selected. If the equation says x cubic inches at x rpm will draw 550CFM, then a 600CFM carb is a good choice. From that point, tailoring the amount of fuel delivered can optimize the package.

Adjusting A/F mixture can affect any setup with any size carb. But to believe that a larger carb will always make more power is misguided in my opinion.

I'm sure there has been cases where a 600CFM was not properly adjusted, although it was actually big enough. Then, a 750CFM was slapped on that was closer to the mark in overall adjustment and an improvement was noticed. The conclusion then might be made that the 750 was better. In reality, the 600 was never properly adjusted or jetted and not given a chance to show what it can do.

Remember, stupid air pump. Fixed amount of air required. Add the correct amount of fuel......done.

1/4 Mile Issues

clement

A5literMan

At least it is lumpy...

NIKwoaC

中國製造

clement

JD1964

there is enough sticking out to grab on to

NIKwoaC

中國製造

84Ttop

They make new pistons every day, so why worry?

A5literMan

At least it is lumpy...

sharp2377

Member

sharp2377

Member

Bullitt347

I have been doing it wrong this whole time

JD1964

there is enough sticking out to grab on to

mikestang63

A5literMan

At least it is lumpy...

NIKwoaC

中國製造

JD1964

there is enough sticking out to grab on to

Similar threads

1/4 Mile Issues

At least it is lumpy...

中國製造

there is enough sticking out to grab on to

中國製造

They make new pistons every day, so why worry?

At least it is lumpy...

Member

Member

I have been doing it wrong this whole time

there is enough sticking out to grab on to

At least it is lumpy...

中國製造

there is enough sticking out to grab on to

Similar threads

Privacy & Transparency

Privacy & Transparency