Superchargedfish67
Member
I have a 67 barracuda with a base 273. I was wondering how much boost it can handle stock. Also what would minimum amount of work so it could handle low boost
Supercharged 273
- Thread starter Superchargedfish67
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pishta
I know I'm right....
Keep it under 10psi and you'll be fine. Wonder how much the steel shim head gaskets can take?
cudavert
DARTAHOLIC
Gee, with their forged cranks and then maybe add a set of high quality rods/forged pistons.....you'd think quite a bit. You could make it like a 340 with a smaller bore.
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TT5.9mag
Two atmospheres are better than one
Welcome to the forum. The 273 will handle as much boost as any other engine really. It’s all in the tune up. Stock without touching the engine? My guess is you’ll push a head gasket out or break a ring land around 8-12psi. Built for boost, the sky is the limit.
Superchargedfish67
Member
Thanks but I know built for boost is unlimited. I have a small budget and making the most power for my money
65TerrorCuda
Well-Known Member
5psi if you don't take anything apart or do the rings like 273 said. Also don't rev it to the moon. Rings might already have a decent gap if it's got 100k on it or 200k. Either way you're gunna want more boost
Cheapest HP for the money... NO2
How power you hoping to get ?
14.7 psi basically doubles the air going into your engine making twice ish and 7.35 psi making 1.5 x the power problem is a 273 doesn’t make much stock power in the first place to multiply.
14.7 psi basically doubles the air going into your engine making twice ish and 7.35 psi making 1.5 x the power problem is a 273 doesn’t make much stock power in the first place to multiply.
Superchargedfish67
Member
Put on a set of open chamber 68 and newer heads and MLS gaskets. two size colder plugs Then let-er rip tat-er chip.
Is this a stock 2bbl engine ??
do you plan on some performance parts or all turbo for 400 hp ??
least to me you would want to do cam and 4bbl and intake maybe a little pocket porting to get NA 250 or so hp and add 7-10 psi of boost for the rest.
do you plan on some performance parts or all turbo for 400 hp ??
least to me you would want to do cam and 4bbl and intake maybe a little pocket porting to get NA 250 or so hp and add 7-10 psi of boost for the rest.
Superchargedfish67
Member
doogievlg
Well-Known Member
I don’t you would see 400 hp out of a blown 273 on 5 psi. With the money you put into the blower it would almost be more effective just to go with a NA 360. Folks like to throw around the 400 hp number a lot when talking about small blocks. Time slips don’t lie and it’s not really cheap anymore to get 400 out of any small block. Grab a 360 and another thousand dollars and you will be in the 300 hp range which really isn’t bad for a little street car. If you want 400 hp though you’re going to be closer to 4,000 in my opinion unless you do the heads yourself.
I'm not condemning it, but the reality AND dependability/longevity of 400 HP is damned near impossible.
The 273 BY FAR is one of the most costly mopar sb to increase HP on. What did the D-Dart get 275hp? Did it even get 300?? And that was a BUTTLOAD of engineers and $$.
Here is a great read from a very knowledgable guy from back in the day.
Paul Cessarine(chk spelling on that).
Oh and our 67 cuda is an S that came factory with Commando, just so you know I ain't slamming it. Just a reality check.
273 Camshaft Specifications
The 273 BY FAR is one of the most costly mopar sb to increase HP on. What did the D-Dart get 275hp? Did it even get 300?? And that was a BUTTLOAD of engineers and $$.
Here is a great read from a very knowledgable guy from back in the day.
Paul Cessarine(chk spelling on that).
Oh and our 67 cuda is an S that came factory with Commando, just so you know I ain't slamming it. Just a reality check.
273 Camshaft Specifications
TT5.9mag
Two atmospheres are better than one
Most of these reply’s are being made by people who have never had an engine in boost of any kind. You can tell. @Oldmanmopar is right on and @Scampin has been there. I’ll add one more thing that will help, head studs. So your list of MINIMUM mods should be;
1. Pull it down and gap the rings to .007/in of bore. Both top and 2nd.
2. MLS head gaskets
3. Head studs
4. Drop 2 heat ranges on the plugs
5. Some way to control timing for boost
6. Some type of boost reference for the carb power valve circuit.
7. A killer fuel system. (Do not cheap out here).
This would be the absolute minimum amount of work to get you in positive pressure and make it live a little while in my opinion.
Then it wouldn't be stock, would it? He asked about a STOCK motor.
Along those lines, I think 10psi would probably be about it. And no guarantees it would hold that, since technically it's not really made for it. But....you asked. lol
Superchargedfish67
Member
I did say what minimum amount of work to go into it to handle the boost. I am open to any mods that aren’t too expensive
I'm not sure the rods pose a weak point. Certainly good rod bolts. I'd run the stock rods and never blink. Course the cost to redo stock rods gets you into aftermarket rod territory....so there's THAT. A good forged piston. Course that means custom. I think it'd be a fun engine.
cudavert
DARTAHOLIC
Well, I think forged pistons and maybe some decent 340 rods wouldn't be breaking the bank too badly. And getting some kind of boost ignition retard unit and a water~methanol injection would probably allow you to run 15 psi safely.
And of course 15 psi needs a really good head gasket. Somebody needs to do this. OP, are you gonna do it? A "not too wild" blown 273 build. Sounds cool. What's the power goal? 400? 450?
D dart was just cam headers and Holley rest was just 273 commando, better intake and a modern cam could get there without being so wild. Especially if you improve the heads.
Superchargedfish67
Member
I may do this depending on price and availability. My power goal is at least 400
I don't think if you went much past 400....maybe 450 tops that you'd ever have a problem with it. Sounds like a super cool project.
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