318 willrun has your answers, he's been working with a low compression 360, step by step he's at 12.8 et in the 1/4, it's not 400 hp but it's pretty respectable and very tame.
400 horsepower low compression 360
- Thread starter ike61
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I had two different name-brand builders recently talk me out of building a 904 for my 408 project. They both said the issue comes down to the ability of the pressure to hold the bands/clutches so the trans don't last. One of them said they don't build the 904's anymore because of that. He said the 727's can handle the grunt much better and are less expensive to build. If just a mild street car the 904 should be fine with quality innards. It is when they are pushed hard that problems start happening.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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Ok hold the phone;
I have a 367 that by it's trapspeed is making 430 hp. I also run a manual trans but with 3.55s.
I know exactly what it takes to run 400hp. and I know,
yur gunna be sorry, unless you swap to 4.30s.
Here's why;
Your starter gear is 2.66 x 3.23= 8.59
Your rear tires are likely to be ~24.5 tall.
To make the 400 out of that combo, with the factory heads, my guess is that you'll need a cam of about 248@050.
The lowest rpm that your 400hp engine will sustain, with that cam/cylinder pressure, in gear, is gunna be ~650 and it will take a helluva tune to achieve that. Thus, the slowest speed you can ever drive is 5.5 mph; And with 400hp on tap, yur gunna need to be a hevckuva tuner, again, to not have the engine get jumpy on you down there.
So, forget parading. and you will be forever slipping the clutch, to drive any slower. And from every light and stopsign, you will be easing it out. Then, when you get to Second, the split is 72%, so say you are just driving "normally", like I do, lol, and you take First out to 2800....... cuz you know, you don't want to sound like a Mustang.
Ok so on the 1-2 Shift, the Rs will drop to 2000rpm........ and your big cam/low-compression/750/Torquer engine, is so far off the torque-peak, it will labor to get back up out of that hole, unless you give it lots of ignition advance, and then you get into detonation.
So then, IMO, you need to rethink the entire combo, else you are gunna end up like me with thousands of dollars worth of parts on the shelf, that did not work.
So again, IMO, you need to ask, a different question, such as,
"what would work with the parts I already have," or
state your budget and let the guys put it together for you.
But above all, state what rear gear you will not consider going bigger than; cuz those 3.23s with a 2.66low A833, are gunna be your limiting factors, for NON-WOT, First gear performance......... and every time the car stops, you are looking to drag yur azz thru first gear again which won't wake up until 3500@ 30 stinking mph, unless the tires are spinning, and that ain't gunna happen unless yur mean to the clutch.
IMHO
a good STREET build for the parts you have, and for your light-weight Valiant would be around 300/330hp.
300 for Iron heads, and 8/1 Scr
330 for alloy heads, new pistons at 10.5 or more, and maybe one size smaller cam.
I made 330hp with a 223/230/110 cam, and that was enough to take my 3650 pound Barracuda to 106 in the quarter, on street tires. Scr was 11.1 with those alloy heads.
I'm still not liking the 3.23s but I'd at least give them a chance. You better have a posi.
Happy HotRodding.
This will have enough grunt to pull that 8.59 starter gear;
100% you should build the powerband to where you want it to work best but if the engine not gonna be able to make the hp/performance you want in that powerband you need lager cid and or add rpm and or power adders.
ir3333
Well-Known Member
These posts always end up in the big hp, big cam, aluminum head quarter mile file.
Op is only driving on the street and the car will likely never see anything above 4000 rpm. 4500 rpm is 100 mph with his 3.23 gears. He may kiss 4800 briefly in first or second gear. Slam in a comp xe 250 and you will boil the rear tires at will and pin your passengers in their seats 'til well past highway speeds. Should produce 350 plus torque at 2000rpm and 400 at 2800 rpm. I'll bet it would be respectable in the quarter mile too!
I can hear the murmurs...
Op is only driving on the street and the car will likely never see anything above 4000 rpm. 4500 rpm is 100 mph with his 3.23 gears. He may kiss 4800 briefly in first or second gear. Slam in a comp xe 250 and you will boil the rear tires at will and pin your passengers in their seats 'til well past highway speeds. Should produce 350 plus torque at 2000rpm and 400 at 2800 rpm. I'll bet it would be respectable in the quarter mile too!
I can hear the murmurs...
100%, some have it in their brains stock has most down low torque which a stock 2bbl 360 has 325-335 lbs-ft between 2,000-3,000 rpm and down hill after that I've yet to see a reasonably built engine do far worst than that.
Here's the results of that low cr 360 video above, 360 heads with 2.02 and mild pocket port, xe250h and xe268h plus other mods, vs stock 360.
It would take a lot more cam to do worse than stock but by then you should be running a 3,000 + rpm stall anyways.
ir3333
Well-Known Member
OP has a 4 sp. When i see street only i think stock converter. I've used a 9" Dynamic converter, the novelty wears off, and i grew to hate driving through the thing on hills or sharp corners at highway speeds. Those TV/you tube guys builds don't seem realistic to me...maybe i'm wrong?
Say that's true how do make the most power there ? torque of course so peak torque at 4,000-5,000 rpm gonna give the most under 5,000 rpm power plus the most 5,500-6,500 rpm power for the few seconds your there.
You may never go above 4,800 rpm, but I do get and agree with what your saying, build it so it works best with how you drive and how you want to play with that power. Everyone is different and wants different things it's up to the OP to figure out what he truly wants.
Drives fine and gets some rpms out of her now and then
"Kansas City Streets GoPro Ride Along 976 HP Brett Miller 434” W9 R3 Small Block Mopar 1968"
MopaR&D
Nerd Member
I put heavily ported Edelbrock heads, RPM intake and custom-grind (.550" lift, 222° intake duration @ .050", 110 LSA) hyd roller cam on a stock bottom end 5.9 Magnum (9:1 compression) and it makes a verified 400+ HP (closer to 420). Might break 450 once I put Doug's headers on, better carb (750 DP instead of street demon) and upgrade the fuel system. It's very streetable, I drive it all the time.
What's my point? You won't make true 400 HP on a 360 with stock low-comp pistons unless you put good-flowing aftermarket heads (or heavily ported iron heads) and a high-lift (over .500") cam. Even with 10:1 it won't be easy if you're sticking with a street-oriented flat-tappet hydraulic cam and factory iron heads.
Shoot for 350 HP, that's much more realistic and plenty of power to have a lot of fun in an A-body.
What's my point? You won't make true 400 HP on a 360 with stock low-comp pistons unless you put good-flowing aftermarket heads (or heavily ported iron heads) and a high-lift (over .500") cam. Even with 10:1 it won't be easy if you're sticking with a street-oriented flat-tappet hydraulic cam and factory iron heads.
Shoot for 350 HP, that's much more realistic and plenty of power to have a lot of fun in an A-body.
He's asking which cam and heads to run, so my guess he's open to aftermarket heads.
That's the guy that got banned from here. lol
I've had 4200+ converters that drove like a stock unit for the most part. Not all converters are created equal and if it drives like stepping on a marshmellow, you need a different piece.
OP has a 4 spd, the auto trans talk is irrelevant. You can do a bunch more with the cam and a 4 speed not having to deal with in gear drag down.
I have a Dart 340 with a 528 mechanical, ld340, 4 speed and 3.23's, 26" tall rear tires. It's fine to drive and responds really nice.
As far as calling the pros, PRH, OU812, Sean NCengine, RAMM sure. There are a bunch of really sharp people in here that have done this stuff a LONG time as well, TT5.9, JYH, Justin, 1wild, I'm forgetting a few others. Better than calling the desk jockeys at some cam companies that never built a thing unless you got to talk with Billy when at comp.
OP has a 4 spd, the auto trans talk is irrelevant. You can do a bunch more with the cam and a 4 speed not having to deal with in gear drag down.
I have a Dart 340 with a 528 mechanical, ld340, 4 speed and 3.23's, 26" tall rear tires. It's fine to drive and responds really nice.
As far as calling the pros, PRH, OU812, Sean NCengine, RAMM sure. There are a bunch of really sharp people in here that have done this stuff a LONG time as well, TT5.9, JYH, Justin, 1wild, I'm forgetting a few others. Better than calling the desk jockeys at some cam companies that never built a thing unless you got to talk with Billy when at comp.
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that's Mr. Brainy Pantaloons to you, sir.
Where did the OP say stock heads, he's asking for cam and head advice.
i love how the exercise was: 400hp with low compression, is it possible?
and here we are talking about gearing... and stall (when the dude doesn't even have an auto), and 1/4 mile times.
it's like OP asked for the weekend weather forecast and y'all are giving him recipes for cookies.
and here we are talking about gearing... and stall (when the dude doesn't even have an auto), and 1/4 mile times.
it's like OP asked for the weekend weather forecast and y'all are giving him recipes for cookies.
You expect anything less?
Cause some think everyone should build a car how they would and can’t see things from other’s perspective.
Some people just want a full throttle blip burnout machine
Others not so much.
today's 400 hp is yesterday's 300. lol
Every dog claims they have, 400, 500 hp when in reality they are barely making 375. lol
low compression is a major hinderance in making 400 hp N/A
well, duh. inflation!
that's just a different version of inflation...
oh i fully agree! but it can be done with the right combo of parts, some shrewd exploitation of bits, seeking areas for small advantages, and throwing preconceived notions out the door.
I don’t think it’s a major hindrance build the 360 like you would for 420-430 hp with 10.5:1 cr and with 8.5:1 it will probably make around 400 hp and a torque and powerband similar to a 400 hp high cr 340.
1WildRT
Well-Known Member
Got banned,,really !
That was the most boring video I have ever watched !
What a let down .
Tommy
Yea, he had a bad ego problem.
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