250ci turbo questions

It would be better to use a little longer connecting rod than stock.
It reduces side loading and the piston can be a little shorter and lighter.

The aftermarket 6.00" longer Chevy 250 six rod can be made to work nicely with a custom piston.
http://www.summitracing.com/parts/sca-66000206.

The big end will need to be narrowed by .056" to fit the 250 crank.
Since the Ford rod journal is 2.123" and the Chevy six is 2.00" you have the option to offset grind the crank rod journal and increase the stroke.
Even if the crank needs to be tuned .020" to clean up the journal surface, the center can be offset .050" to gain .100" stroke

We use Diamond pistons in our racing engines and they will make you what you need.
 
pmuller9":1prl0ugg said:
blackbird64":1prl0ugg said:
right now like you were saying the cam intake and exhaust can be the same what is a good cam for max of 20lbs boost oh and im guessing other things take into play such as valve size ,springs, rockers, ignition etc
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The engine needs to produce just over 200 hp without boost to get 500 hp with 20 lbs of boost.
The OZ250-2v head should be able to make the power between 5000 and 5500 rpm using a cam with around a 232/232 .050" duration .500" lift on a 112* LSA.
I would go with Schneider cams.
For race application I would use a solid lifter cam with EDM oiling hole lifters.

blackbird64":1prl0ugg said:
and for fuel i have two vvc carbs about 1250cfm each
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If we go optimistic and look at the 250 six at 6000 rpm and don't adjust for VE and carburetor pressure drop, we get 434 cfm.
A 500 cfm carb will easily supply the air needed in a blow through set-up
1250 cfm is way too big for this application
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So what your saying is that make the engine have 200hp without boost and about 5000 rpm boost to 20lbs this setup will make me 500hp and use a 4v carb at about 500 cfm do i got this correct
 
blackbird64":b1y9domi said:
So what your saying is that make the engine have 200hp without boost and about 5000 rpm boost to 20lbs this setup will make me 500hp and use a 4v carb at about 500 cfm do i got this correct
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That is correct. The Carb needs to be modified for pressure and additional fuel flow.

I realize that I previously mention EFI but a "Blow Through" carb and an ignition system that controls timing with boost will work also and save you some money.
 
[/quote]I realize that I previously mention EFI but a "Blow Through" carb and an ignition system that controls timing with boost will work also and save you some money.[/quote]

What kind of efi set up does that ive actually never heard of that kinda setup sounds cool
 
A lot of users like to use the MegaSquirt system where you configure a lot of the system yourself.
It's one of the least expensive but can be a lot of work to get it running for a particular engine.

I recommend the Holley HP system where the fuel and ignition control and drive circuits are all in one and all wire harnesses and sensors are included.
Here is the universal system that will work with the straight six.
https://www.holley.com/products/fuel_sy ... s/550-605N
 
ill have to look into efi but you can have a turbo carb i like carbs because the only thing that goes wrong with them is a cable
 
If your car is fast how do you keep the fuel from sliding away from the carb suc points and running damaging lean!
and you can not control timing or log data with out more boxes.
 
drag-200stang":2f7jrqb2 said:
If your car is fast how do you keep the fuel from sliding away from the carb suc points and running damaging lean!
and you can not control timing or log data with out more boxes.
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We've used carbs well into the sevens without a problem.
But you do bring up a very important point and that is data logging. Never go racing without it!!

blackbird64
EFI systems do have internal data logging and it is very important to record the Air/fuel ratio, Boost, intake air temps, water temp, oil pressure, ect....
It is far less expensive to use an EFI with internal logging than to use a carb that needs a stand alone ignition system and a separate data logger like a Racepak unit with sensors.
Just something to consider.

I'd like to know how much engine building experience you have so we can better help you.
This is not an easy project.
 
As I said before check out the FI Tech fuel injection system, new out. Their prices range from $795 up . I checked with tech support and their answer is their system should work well with a 250 -6.
 
pmuller9":1qwn3ujj said:
drag-200stang":1qwn3ujj said:
If your car is fast how do you keep the fuel from sliding away from the carb suc points and running damaging lean!
and you can not control timing or log data with out more boxes.
Click to expand...
We've used carbs well into the sevens without a problem.
But you do bring up a very important point and that is data logging. Never go racing without it!!

blackbird64
EFI systems do have internal data logging and it is very important to record the Air/fuel ratio, Boost, intake air temps, water temp, oil pressure, ect....
It is far less expensive to use an EFI with internal logging than to use a carb that needs a stand alone ignition system and a separate data logger like a Racepak unit with sensors.
Just something to consider.

I'd like to know how much engine building experience you have so we can better help you.
This is not an easy project.
Click to expand...
I dont have any experience with any of this stuff so alot of the stuff you guys are talking about are totally new to me im only 17 so
 
I'd like to offer a suggestion.

Prior to building something as extreme as you've described with the fairly aggressive goals you've listed, you might want to first build up some experience with a more tame and proven combination that will have less variability and fewer opportunities for problems/failure.

I mean no disrespect. I believe you will very much benefit from something more easily accomplishable; at least initially.
 
blackbird64":2g63gocg said:
so you would get a simple project to start out
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I think he was implying you should tone your first build down to something less likely to go "bang" the first time you stomp the gas, and be more easily accomplished... To meet the goals you describe (10s 1/4mile) will cost many thousands of $, custom/un-obtainable parts, etc...

Since you have a 2V head, perhaps a mild Naturally Aspirated build, with low enough compression that you could add a mild (under 10psi) turbo setup to later. When you build an engine right at the edge, when any little thing goes wrong (like a ping), you get a hand grenade, whereas a mild engine might survive, and since this will be your first experience with tuning, it would suck to "blow the motor" before you even get it tuned correctly...
 
Me?

I would build a rock solid bottom end and initially run a naturally aspirated engine with a two barrel.

Later, once that was running like a swiss watch, I'd add a simple j-pipe and turbo and learn a whole lot on the process. I would start with something small and street-able.

While you can coax gobs of power out of most engines, it usually costs cubic $ unless you just throw in an enormous engine.

So, I would start off smallish - then add an intercooler and (later) a larger turbo and fuel injection.

You will maintain progress, in my opinion, if you set smaller goals that allow you to celebrate littler victories along the way.
 
You are getting good advice.

Build the 250 with the good rods and pistons along with the OZ250-2V head.
Run it without the turbo at first and take the time to sort out the rest of the car.
There are a lot of things that are needed on a drag race car that aren't needed on the street.

When the turbo is installed before you can run full boost the rest of the drive train will need to be modified to handle the torque.
At full boost you are looking at over 600 ft lbs of torque.

You will need a performance built manual C4 transmission that has a transbrake with a high stall speed torque converter.
The rear end will need to be changed to a performance unit, possibly a Ford 9".
Add wheels, tires and brakes, wheel well mods, suspension mods, ect...

As previously mentioned, as the horsepower goes up, so does the money outlay for the rest of the car to support the extra power.
You will also need to get the rule book for the track you will be running at and see what the requirements are for a 10 second car.

The other part to this is, the engine build requires a competent machine shop to do the machining on the engine parts.
Do you have a trusted performance engine shop in your area?

Question#2, do you have a starting budget for this project?
 
not really i was just going to buy parts as i had the money, second you guys keep mentioning rods and pistons where would you go for that stuff because classic inlines only has forged pistons
 
You no longer can order from Classic Inlines.
Does10s on this site has all the remaining inventory.

Here is the previous post (about 17 post up) where I mentioned one possibility for a connecting rod and piston.
viewtopic.php?p=576166#p576166.

You will need 3 rev limiters, the ability to map the timing with rpm and also be able to map the timing based on manifold pressure/vacuum.
The MSD 6530 programmable 6AL2 will do the job.

Like I said before, a vehicle set up for drag racing requires different equipment than for street use.
 
blackbird64":3hud0zvy said:
not really i was just going to buy parts as i had the money, second you guys keep mentioning rods and pistons where would you go for that stuff because classic inlines only has forged pistons
Click to expand...
Classic inlines is no more, do not order... money will be taken, no parts will ever ship...
 
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