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How to achieve 425 HP and 500 TQ from a 400 cubic in engine?

If all you want is a street/highway cruiser don't put a number on it.

That’s my take on it as well.

Build it appropriately for the job at hand, and it’ll just make what it makes.

Want more(seat of the pants) power without making it rowdier?
More cubes is the answer imo.
 
Sorry, that's just not true. I built a 383/438" 9.3:1 stroker for a friend with untouched "OOTB" Stealth heads that made around 450hp/475lb ft of torque with a relatively mild Hughes cam. Headers, Performer RPM intake, 750 DP carb. OK, it had Comp Magnum roller rockers... "Mineshaft" air that day, the dyno actually took away some power. Hydraulic roller would probably be another 25 hp...
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This engine went in a 100% street/highway cruiser C body and the guy loves it. It's the most power he's ever had under his right foot.
That's great, I don't guess numbers, I've always built engines that exceeded the intended goal.
I don't start with OOTB cylinder head in most cases and if I did I'd go straight to the Trick Flow.
I also see no sense running a dual plane intake on anything over 426 CI.
 
That's great, I don't guess numbers, I've always built engines that exceeded the intended goal.
I don't start with OOTB cylinder head in most cases and if I did I'd go straight to the Trick Flow.
I also see no sense running a dual plane intake on anything over 426 CI.
No rpm performer intake on a 440 in any use case?
 
That's great, I don't guess numbers, I've always built engines that exceeded the intended goal.
We actually were shooting for around 450 hp so we were happy with the numbers it put up. It's really only 1 hp/c.i. (438") which is a basic hot rod engine. We purposely kept it mild for low maintenance and drivability. Regardless, it sounds great, can do block-long burnouts and will break the tires loose when it kicks down from 40mph roll. It would have easily made better power with more compression and a bigger cam. If you think about it, 475 lb./ft. @ 4,100 rpm would certainly be at the top of the heap back in the muscle car days.

I don't start with OOTB cylinder head in most cases and if I did I'd go straight to the Trick Flow.
There was no need to mess with the heads on the engine I showed, it wouldn't have made a lick of difference - the camshaft was mild and the engine will spend the majority of it's life at part throttle. Plus, it simply wasn't in the budget. I can't do my own valve jobs and I'm dangerous with a grinder so those operations would have been an extra cost which was not in the cards. The beauty of Stealth heads is that they are a bolt-on, stock-replacement deal and relatively cheap. Sinking money or time into brand new heads 'just cause' would have made little sense. Trick Flows would have been overkill for that combo and would never be fully utilized.

I also see no sense running a dual plane intake on anything over 426 CI.
Intake choice is generally dependent on application rpm, not displacement. Again, the 438" I showed was a 100% street cruiser combo in a heavy car with highway gears - it needs low rpm torque which is the whole point of a dual plane. It would be pointless for an engine like that to only make power above 3,500 rpm when the car is mostly putting around crowded urban streets or on the highway.
 
I don't start with OOTB cylinder head in most cases and if I did I'd go straight to the Trick Flow.
I also see no sense running a dual plane intake on anything over 426 CI.

Pretty much agree, but you are painting with a pretty wide brush. Budget and intended purpose matter.

There is a pretty wide overlap in hp range where both the single and dual plane intakes work well.
 
A little food for thought on the Stealth heads…..

In the EM head shootout where they tested stock heads vs stealth vs rpm vs tf…….there was roughly a 20hp spread for each swap.

If you do a more performance oriented valve job and blend the bowls on the stealth heads, you would wipe out most of the flow difference between them vs the ootb rpm.
I doubt there’s more than 2-3cc’s of material removal involved for upwards of a 15-20cfm gain, at lifts within reach of a typical 500hp cam.
I think that 20hp spread the EM test showed between the ootb stealth vs the ootb rpm would be pretty much eliminated with that level of rework.
 
You could easily achieve your goal if you get rid of the thermoquad. Use a Holley and convert it to burn E85, you'll need a plastic fuel cell, rubber lines, and an alcohol pump/regulator to run it of course. Cut the stock heads to raise the compression, I'd probably go about 11:1, maybe higher. Maybe upgrade the pistons too. Any aluminum intake will work, I'd recommend a dual plane. A stock HP cam will work fine but you could go bigger if you can give up torque. I've done this to countless late 70s police 440s and they'll make about the power you want. Runs 7.50s in the 1/8 at 3600lbs. A 400 shouldn't be too far behind that.
 
Build a mild stroker. Also, call Bullet Cams for a custom grind. Avoid Comp Cams like the plague.
I've seen this comment a few times now, I believe all from you. I'm curious as to why you feel so negative about a brand that has served me and most of the gearheads I know, well for a whole lot of years. If you have a personal story I'd love to hear it...
 
I've seen this comment a few times now, I believe all from you. I'm curious as to why you feel so negative about a brand that has served me and most of the gearheads I know, well for a whole lot of years. If you have a personal story I'd love to hear it...
I haven’t had a Comp Cam fail since 1985, but there are tons of stories out there about them failing in recent years. I much prefer to buy a custom grind from a small cam grinder than from a giant company that is owned by a private equity firm.

You’ll get a better product from a small cam grinder than you will buying an off the shelf one from Comp.

You do you, but I’ll always go with Bullet as long as they are around.
 
Come, on, Comp Cams are fine. I'm not a shill for them and could care less about what brand anyone chooses but the reality is that they sell millions of camshafts a lot of which are spec'd by pro builders. If they were really poor quality they'd be out of business.

I'd bet that most Comp Cams "failures" you read about on the 'ol interwebs can be attributed to operator error. It's the same with a lot of brand names that get bad mouthed because someone screwed something up and it caused them a lot of grief and they're looking to blame something other than themselves. For example, read the blurb on the Holley website about their discounted refurbished parts. They actually say that 9 times out of 10 there is nothing wrong with the returned parts except for incorrect installation.

I'm sure the OP here would be fine with an off-the-shelf Comp cam. If it's installed and broken-in correctly it will live a long, happy life.
 
I haven’t had a Comp Cam fail since 1985, but there are tons of stories out there about them failing in recent years. I much prefer to buy a custom grind from a small cam grinder than from a giant company that is owned by a private equity firm.

You’ll get a better product from a small cam grinder than you will buying an off the shelf one from Comp.

You do you, but I’ll always go with Bullet as long as they are around.
So basically, you are repeating stories from individuals you don't know, not from personal experience with Comp products. I encourage you to take a walk through the pits of any major race, be it NHRA (my personal experience) or any other professional, organized event and look for Comp decals on the entrants. Then actually talk to the owners and drivers about their experiences with that brand. There is a reason they are picked to power so many professional and amateur vehicles, not to mention thousands of street vehicles. I'm not saying that Comp is the only cam/lifter brand to use. Everyone has their favorites that have worked well for them. What I'm saying is I don't think it is right to bad mouth a product based on somebody else's post without FIRST HAND knowledge of the build and break-in. And, btw, all cam companies offer contingency money if you actually use their product and win an event...
 
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I'm going with a comp xe275hl on a 395cid small block, aiming for 500lbft, so similar size with similar goals. I look at Blueprint Engines and see what head flows and cams sizes they use on ~400cid engines with the same power. If you can match the the part specs you there you should match the power level.

Biggest issue with your combination is probably the exhaust manifolds. You are going to have a hard time with restriction there without spending time and money porting those. Even then they will be worse than the budget basement headers.
 
My last slider cam was a Lunati voodoo solid lifter cam broke in fine never had any issues. Depends on the quality of the core. I will most like use another one, but a hydraulic.
 
Although Edelbrock owns Lunati, they use Comp Cams to actually make the Lunati cams. Now they're phasing them out, if you're on the Lunati website, they no longer have any cams listed in that section of their catalog.
 
So basically, you are repeating stories from individuals you don't know, not from personal experience with Comp products. I encourage you to take a walk through the pits of any major race, be it NHRA (my personal experience) or any other professional, organized event and look for Comp decals on the entrants. Then actually talk to the owners and drivers about their experiences with that brand. There is a reason they are picked to power so many professional and amateur vehicles, not to mention thousands of street vehicles. I'm not saying that Comp is the only cam/lifter brand to use. Everyone has their favorites that have worked well for them. What I'm saying is I don't think it is right to bad mouth a product based on somebody else's post without FIRST HAND knowledge of the build and break-in. And, btw, all cam companies offer contingency money if you actually use their product and win an event...
Most of the NHRA stockers required to run flat tappet cams are running billet cams with Trend tool steel lifters. The good cast cam cores that Comp and the others used are no longer being made or available.
 
I watched, heard, and saw TWO comp XE268 cams go flat on a run stand less that one month apart. Maybe the would made in the same lot. But sorry, burned twice.

I sold the engine builder a NOS one above stock (455" lift?) Mopar Performance cam and lifter set made in late 90's.

...Its been fine in that car for for about 5 years now.

Same guy was helping young guy build his first motor about 3 years ago. Had a Comp timing chain. timing slots were machined wrong. Got another chain set and all was fine.

I have a comp cam flat tappet solid made in 2010. It's been fine.
 
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