Will stock factory Chrysler 400 cast pistons hold up to 6-8 PSI of boost if driven responsibly? Thank you drive through.
Stock 400 Piston Boost
- Thread starter RustyRatRod
- Start date
If driven responsibly means avoiding detonation at all costs, then yes, no problem. That may require a target closer to 5 to 7 pounds of boost, depending on your cylinder heads, but really splitting hairs. Sounds like fun, BTW!
5-7.....whatever. I'm thinking about a 6-71 stickin through Vixen's hood. The 400 only has 7.7:1 static compression. I think a blower might be cool. The swap is not happening anytime soon, so I thought I might do something kinda cool.
Oh, definitely cool, and maybe way too much fun, ain't nothing like roots boost. Okay, I was thinking around maybe 8.5:1. with 7.7:1, 8 pounds of boost is no problem. Especially in something that light. Looking at what, around 3000 pounds with driver and a blown big block?
Maybe. I'm not sure it would tip the scales that heavy. It might. I ain't gettin no skinnier.
And yeah, I'm still gonna leave it three on the tree. I think the A-230 will hold up.
67Dart273
Well-Known Member
There's always water. Injection, that is. This is one place modern alky infested fuel would help
Here's a question..............could ya hack up a SB distributor so the vacuum advance RETARDS the timing?
Here's a question..............could ya hack up a SB distributor so the vacuum advance RETARDS the timing?
It may be old school, but locking the distributor and implementing some form of start retard helps keep detonation in check. My biggest concern would be cooling it in the Georgia heat and humidity. That in itself makes makes an excellent case for the snow performance blue washer fluid injection setup.
j par
Well-hung Member
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With 7.7 compression and 5 PSI boost, yall really think it's need boost retard?
j par
Well-hung Member
I hear you there'll be plenty of retard in the car already...
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j par
Well-hung Member
You don't think going from a slant 6 to a 400 going to be enough of a step?.
Sure, but it's not gonna happen anytime soon, plus, I've always wanted to build another blower motor.
famous bob
mopar misfit
Interesting , I remember u saying it was going to stay a stock driver , way back there . When u said it , I thot , yeah right !
Once a hot rodder , always a hot rodder !
RammerJammer75
Well-Known Member
I would. Or use some really good gas, like 114 or methanol/water injection. One good round of detonation on those cast pistons and they're gone.
About 36 degrees of static timing with the coldest plug it will reliably run with and 20 degrees of start retard and you’ll be fine. Somewhere in the 12-1/2 % under drive range should deliver around 7 pounds of boost. The water meth injection is a necessity, though.
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Rob, as far back as I can remember, the idea of adding boost required 2 things, and just these two items alone.
1: A good cylinder wall finish and a good ring to seal.
2: A wider gap, gapped larger for the amount of boost intended.
When Gramps went racing, this was the finished target goal. Of course you have this idea in your head about the cast pistons. Being to weak. There is some truth to that. Gramps would say, something like, when you get past two atmospheres’, call me.
I don’t have him around anymore. But I think you’ll find this guy very helpful.
https://www.youtube.com/channel/UC8uf_zVTV63l1-uRSx6XbnQ
1: A good cylinder wall finish and a good ring to seal.
2: A wider gap, gapped larger for the amount of boost intended.
When Gramps went racing, this was the finished target goal. Of course you have this idea in your head about the cast pistons. Being to weak. There is some truth to that. Gramps would say, something like, when you get past two atmospheres’, call me.
I don’t have him around anymore. But I think you’ll find this guy very helpful.
https://www.youtube.com/channel/UC8uf_zVTV63l1-uRSx6XbnQ
Curious as to what your carb preference is. If you could score a good rebuildable core, a single Dominator with progressive linkage might be your best friend here.
I bet two 1000 cfm ThermoQuads could be heard overtop of the blower whine!
I’d call it a symphony!
Well, I have LOTS of time now since I repaired the 170, so I can do pretty much anything. I have no qualms about tearing it back apart and going with some forged pistons and a forged 383 crank. None at all. That said, I'm still happy with the car as it is......so anything added will be icing on the cake.
Well, that link to Richard Holdner has many dyno tests that are pressurized engines. The big thing is the ring end gap. If the engine starts its life with you having a good leak down test, then it’s just ring gap issues to address.
Being a cast piston and low boost, a thing done over and over for decades, you’ll have no problem. The big power at low boost (5-7 or so) is the same as a well working NA engine. Easy breathing in, easy breathing out will make more power and possibly lower the boost pressure while your at it.
Being a cast piston and low boost, a thing done over and over for decades, you’ll have no problem. The big power at low boost (5-7 or so) is the same as a well working NA engine. Easy breathing in, easy breathing out will make more power and possibly lower the boost pressure while your at it.
TT5.9mag
Two atmospheres are better than one
The piston itself will hold up to the amount of cylinder pressure just fine. The reason NOT to use them in a boosted application is their tolerance to detonation. Has it been done? Yes of course. Can it be done? Yes of course. Should it be done? The Answer to that question comes in the form of another question. How good of a tuner are you? And can you keep the thing from rattling under boost. Any detonation at all will destroy a cast piston quickly where a forged piston would live. And yes at 6-8 psi from a roost (which is a giant heat pump) you should pull timing on pump gas. Start pulling 2 degrees per pound and tune from there.
Ive been running a stock cast piston 440,stock 452 heads with shims under the intake springs,stock 1976 new yorker cam since 1995. 6lbs boost,28 degs total timing no retard,eng cost me 5oo dol. Broke 1 cast crank balancer, makes a great cruiser .
