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what is the diff. between a crate carb and a reg. carb? i have a 650 demon carb and wondering if it will work?
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crate carb is calibrated properly for the application
every engine has different air/fuel requirements throughout the power band
a simple carb size (650) is only the begining of the equation
Brad
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We still chassis dyno carbs for FREE on our 604 Chassis DYno mule. We run it a couple times and see how it does on a fuel like you run, or if it is one of the 20+ we have on hand we run the same stuff. If you want the carb back as is all you pay is return shipping. If you want it updated to run a better fuel curve for the application, we can get that done also. Costs run $125-$250 if the carb is in good shape. Baseline rebuild on junkers is $125. Shipping with insurance is about $35-$50. Tkaes 2 weeks, sometimes more depending on how much we do...
We have done well over 200 carbs in the last 3 years.
This is the single biggest gain you can make on your engine.
Other areas of big improvement is matching the burn curve of your fuel the the acceleration curve of the engine, and the ignition curve is critical in that area. Locked out distributors is 60's technology and just taking the easy way out. A well built and maintained distributor will not throw a spring or weight. On average a curved distributor is an easy 5-10hp gain.
One thing I have found over the last 25 years, tuning on the engine dyno is one thing but using the acceleration curve of the engine with race gearing is quite a bit different. Just ask anybody who has done both, engine dynos like a lot of ignition timing and lean running carbs. The same engine fresh off the engine dyno and tuned properly on a chassis dyno can result in +20-30HP.
After comparing same engine runs on both engine and chassis dynos it is obvious which one is closer to the on track engine performance. My personal opinion is that both tools are necessary to properly break-in and tune a racing crate engine. We have seen a difference in +20hp just in break-in procedures on out of the box new crates.
Like everything else in racing, attention to detail is the difference between the winner and all the rest.Comment
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So if i send u my carb, you can do what you do and give me back a carb as good if not better than a willeys or stealth. For less than roughly $400.00Comment
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As much as I hate to agree with dynoman, he's right about this. The carb is the single most important area you can get LEGAL HP gains on a crate motor.Originally posted by steelkiwi75 View Post
His pricing is also about right for the market. You don't have to buy a $1200 carb to be in the game. If you've already got a 650 or 750 sitting around, most good carb guys can get you running for well under $500 and that carb will be just as good (if not better) as the $1200 one from brand X.Comment
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One of the problems with Dyno is he will not send out a single part if it is going to be tested b someone else and if he thinks you are going to have them tested he will not sell them to you BUT! He is willing to test everybody elses carbs for free, that way he can see what everyone is doing and if it works or not and then if it is better than his it is easy to change the numbers on the dyno runs to make his stuff look better and talk someone into sending him $$$$.
As far as the best carb, there are MANY engine builders that are using Willys carbs.Comment
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We used a Willy's 750 for our Super Stock, great carb, and then we had them go through our 1,000 cfm Braswell for the DLM. Never had any complaints when it comes to Willys...Comment
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i am going to give david smith a call to see what he can do on my race demon. any other carb guys names and numbers would be appreciated. thanks dennisComment
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carb
call john at jdr performance, he just sent mine back and it works great,,, 4178592353Originally posted by steelkiwi75 View PostComment
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Carburetor testing and other fuel thoughts
Kiwi,
I get hammered a lot on here because I don't do things like everybody else does.
John @ JDR does good work and his carbs are smooth and make good power.
Willy's stuff runs good, the adjusta jet can be finicky to make the most power as they have a couple little mods that really help them +15hp pretty easy. I spent a week at his shop a while back and ran his stuff and my stuff on 3 of my engines and the results were pretty amazing according to him and his folks.
David Smiths' stuff is really good, he used to dyno his carbs on my chassis dyno and one of the first Reality TV shows was shot at my shop, with his car and drive along with Kenny Harriss. There were 3 shows that aired and they were "Grassroots of Dirt". They shot an additional 3 shows at my shop that were more "hi-tech" mostly chassis dyno & only available on DVD and 5000 copies sold out immediately after they aired and we not re-produced.
As far as looking at other folks stuff, there is not that much out there that people are doing. I have never copied another carb as there is not anything out there that runs similar to my stuff, just ask someone who has one.
I run on the fat end of the fuel curve with very low engine timing, I run matching timing advance curves to take advantage of the fuel distillation curve ( I run your fuel to tune carb and dizzy ) and I use the inertia of the drivetrain system to coil the rubber band and launch the car in my inertia acceleration system.
If you watched F-1 with Steve Matchett this year you saw Petronas testing fuel for each team probably 3-4 times a day. The distillation curve of fuel varies from batch to batch and they want to make sure that teams don't burn up engines as even the best fuel in the world varies 1-2% batch to batch. Ever wonder why your engine runs better every time you get new fuel??? Ever wonder why the power varies a lot week to week. Until you have precision control of your fuel supply you will never get a true handle running your engine to consistent performance.
Over the winter while I crawled out of my little hole and went to Italy, I was able to do 4 weeks & 2 weeks of testing with my in-vehicle "real time" dyno system and positive results were verified on 250mph rolling road wind tunnel with both 2-wheel and 4-wheel dyno systems with both F-1 and Moto-GP drivetrains.
Needless to say you will see marked improvement from the teams running Red paint schemes.
Just one quick thing for all of you folks that want to do the test on your own.
Run your timing @ 38 and turn the starter over...
Run your timing @ 28 ......
Run your timing @ 18 .....
When engines get hot 10 laps into a race, most race cars won't start, and have to be pushed off...ever wonder why???
You are dragging your engine around the track 100% of the time and it is compression braking under acceleration and deceleration in excess of 25+RWHP just for 10* of timing.
Imagine what you could do if you could make equivalent power with 10* less timing.
Imagine what kind of power you could make if you matched the burn curve of your fuel to the burn curve the engine wanted, and then once you found that...you matched the acceleration of the engine to the burn rate by working with the ignition system. You won't see many folks talk about it because they don't have the tools, time or motivation to test it.
In this world today folks don't want to put the work in they just want to "buy it done".
That is the future of racing and some folks have been working on it for a while.Comment
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