[Skippy597]

Sorry to use the forum as a sounding board but I really appreciate everyone's views here.

I'm building my 66 lemans with muncie m20 and 8.2 10 bolt posi with 3.36 gears.

I recently asked opinions on doing a budget cast crank stroker build but that was shot down and pushed me in the direction of a forged build. But now I'm wondering if I should just build a healthy 400. I already have speedmaster heads, voodoo 703 cam (was gonna use on another build), HLJ lifters, and some HS 1.65 rockers. I was looking earlier and saw that speed pro forged pistons are incredibly affordable and when paired with some new eagle I beam rods I think I'll have a pretty good build.

Looking to get at least 400hp but I figure with this build my drive train would.last a lot longer and I could probably drive it harder and have more fun with it while saving money.

What are your guys thoughts? Should I build a cheaper 400 or build the stroker and eventually upgrade as I break stuff?

[steve25]

When I see horse power want's / needs posted up as in your case 400, I always ask myself well does this person even know what a true solid 350 hp feels like under there right foot?

When I put myself in your shoes I find myself between a rock and a hard place because of the parts you have.

1). A 400 cid motor would sure help your 8.2 rear live longer then having a 461 with a 4 speed behind it.

2). A 461 would sure have far better throttle responce and everyday street manors with a 215 CC port volume of the aftermarket heads. But the 8.2 rear will be the cars undoing .

3) with either motor if your not running a T2 Intake or a similar Intake to a Perfromer rpm along with enough Cam lift (.550" minimum) then your not going to be making good use of those aftermarket heads.

In the end I think would build the 400 and get 2 years or so of fun out of it while saving up for a good stroker kit to up grade it with down the road so to speak

[besserspat]

Well the 400 can do about 86% of what a 461 will everbbe able to put out ...:-) its was too easy...but also true 😋

[PunchT37]

400’s are made for stick shift.

[JLMounce]

What do you want? This is a big undertaking building an engine. You're always going to be money ahead by doing it right and doing it once. You also have to take into account how the car will be used, the rest of its drivetrain etc.

We know you are currently power limited by your drivetrain. If you are never going to upgrade those pieces, you should take that into account with your engine build. If your plan is to replace them as needed, or when budget comes available, that should also be taken into account.

If you told me, I don't want to upgrade my trans and rear, I'd say build the 400. You'll have plenty of fun with it and you'll save a little bit of coin by being able to utilize your factory crankshaft. If you save $1500.00 on the build, how many miles of gas does that buy you to enjoy the car?

If you really want the stroker and you're not against upgrading the drivetrain as needed, get what you want and do it once. That's my advice anyway.

[BILL BOWMAN1]

Go bigger now… you don’t have to beat the snot out of it.. long as your not putting a sticky tire under it, that usually when stuff breaks .

[Skippy597]

I do have a performer rpm intake as well. Ya know I keep seeing guys say the 215cc runners are too big for anything under a 455 but yet the rest of the speed world would disagree. There are tons of SBC heads and ls1 heads with 215 cc runners and obviously not for a stock motor but they seem to run pretty well on a 350-400ci motor. I know your smarter than me on this Steve but I feel that while not optimized should still be just fine. Obviously it would like the higher rpm range but I think it will be OK.

And yes I've played with more than 350 hp in a few different builds, even my stock truck makes more than that.

[Skippy597]

Sounds like I should just go with the stroker now and upgrade as needed later. I suppose $2000 in the grand scheme of things isn't too bad, it's just easy to get a little overwhelmed with the cost of everything.

[b-man]

It’s not like a 400 can’t be an awesome street engine.

With a stick shift you’ll have a little more rpm and it won’t have so much bottom end torque that it blows the tires off so easily.

You can easily build a nice 450-475 hp 400 with what you have already and have a very satisfying street engine.

[Skippy597]

See if I could get an honest 425hp I think I'd be perfectly happy. I know I could still break the m20 or the 8.2 but with less torque should last longer I would think. What kills me is the lack of affordable headers for rd port heads. Probably would have been better off buying a set of ported d port heads off a member than buying the speedmasters

[b-man]

You’re going to need quality headers (expensive) no matter what heads you’re using so just get a set and git ‘er done.

Round port headers are so much easier to install compared to D-port, there’s really no comparison so they’re worth the extra expense.

[Skippy597]

Fair enough. Are there any members on here with speedmasters or edelbrock rd ports on a 400 engine?

[steve25]

Skippy here’s some important info that you and others need to 1) understand and 2) keep in mind.

To make higher VE numbers over 100% there’s two ways you can go .
In a full race motor with a optimized header and open exh with the needed length collector extension you can use the end of the overlap cycle to give a early start to the intake cycle even though the piston has not started it’s way down the bore.

The other thing a race motor can make use of is ram action to increase the VE percentage.

Now a none flat out race motor can really only attain a higher VE % by means of this ram tuning act.

With either motor you considering building you must maximize the Ram action, and also with either of these motors the average port velocity is just as important as the amount of air getting into each cylinder.

It just so happens that Ram action / kinetic energy increases with the square of its velocity.
Let’s go over that again because it’s so important, Kinetic energy increases with the square of it velocity.

So intake port and intake runner area that is not used to it’s full potential Is more detrimental to performance then having a bit too much port velocity.

Indy motors and cylinder head designers like Harry Weslake even over 15 years ago now started to design for intake port velocities of 400 to 450 fps while your 215 CC heads used on a 400 will be hard pressed to get to 350 fps at rpms under 5000.

How often and for how long do you think either of these motors will be above 5000 rpm?

If you like I can post up a dyno sheet of a 400 street build .
This 400 made 470 plus Hp with iron heads ported to 265 intake cfm, but with only an intake port volume of 180 CCs.

This 400 build used as big of a cam as most folks could tolerate in a street strip motor.and peak torque did not come in until 4600, so 4600 rpm with 180 CC intake ports.

At 3200 rpm torque was down to 411.


What kind of rear gears do you foresee needing to make use of a peak torque value coming in at 4600 rpm?

When you have a motor breathing thru heads that have more port area / volume than needed there are two ways to make things better.

1). You run lot of valve lift .

When you move more air thru a given amount of port area you in turn increase the port velocity once the motor is up to a rpm where it needs that level of air flow.

2) reving the motor higher will increase port velocity also.

You will find that a 400 with 215 CC intake ports will need to be built to go to a shift point of 6700 .

A 461 cid motor is only 13% bigger in CID so that will need to built to go to 5800 rpm to hit peak Hp with those same 215 CC ports.

I hope some of this helps.

[Skippy597]

Steve, as always I greatly appreciate your knowledge and input!

I see where the facts are pointing to and I do understand the theory just fine. I guess more of what I'm asking is while not ideal or optimized will it be a total dog on a 400 with these heads and does anyone have first hand experience? The 703 cam with 1.65 rockers will be in the .530/.550 lift range (can't remember the exact numbers) so.it won't have huge lift but not small either. But this is the type of info I appreciate as I don't want to waste money on a build.

Maybe I should try trading for a set of ported d port heads? Or maybe I should just build the stroker.

[i82much]

I find driving a bigger engine to be EASIER on the drivetrain in a street car. With a smaller engine you have to rev it up higher, tends to shock the clutch, trans, rear end. With a bigger engine you just kind of roll into the throttle, poop your pants a little bit, slow back down, find another straight stretch and do it again!

[jhein]

The Voodoo 703 will be pretty small for a stroker. Maybe even a little small for a 400 if you want 425+ hp.

From a driving perspective, the stroker will behave really different than a 400. There's so much more torque with a stroker. In my car it makes 1st gear almost useless. Well, not useless really but it takes a lot of finesse to not fry the tires. Even in 2nd gear it's touchy.

So if your not looking for something like 500 hp, then maybe a really healthy, snappy 400 will give you what you want and maybe more user friendly on the street than a stroker.

[Skippy597]

Originally Posted by i82much

I find driving a bigger engine to be EASIER on the drivetrain in a street car. With a smaller engine you have to rev it up higher, tends to shock the clutch, trans, rear end. With a bigger engine you just kind of roll into the throttle, poop your pants a little bit, slow back down, find another straight stretch and do it again!

This is the perfect answer. Lol

[Skippy597]

Originally Posted by jhein

The Voodoo 703 will be pretty small for a stroker. Maybe even a little small for a 400 if you want 425+ hp.

From a driving perspective, the stroker will behave really different than a 400. There's so much more torque with a stroker. In my car it makes 1st gear almost useless. Well, not useless really but it takes a lot of finesse to not fry the tires. Even in 2nd gear it's touchy.

So if your not looking for something like 500 hp, then maybe a really healthy, snappy 400 will give you what you want and maybe more user friendly on the street than a stroker.

I have an RAIV melling spc-8 for the stroker build. The 703 was for a different build ans has been sitting on my shelf.

[b-man]

The 703 cam would be good with the 3.36 gears in a 400.

If you had say 3.70 or 3.90 gears then the RAIV cam would be good.

You should easily reach your 425 hp goal, a stock RAIV 400 with heads that only flow 220 intake makes 425 hp although factory rated at 370 in the GTO.

Seriously who believes a RAIV makes only 4 more horsepower than the 366 hp D-port RAIII that has maybe 190 cfm heads with a smaller cam.

The Edelbrock power package that included the 280 cfm 72cc aluminum heads designed for a 400, a copy of the RAIV cam and the Performer RPM intake was advertised as making 425 hp if I’m not mistaken.

A 400 won’t be a slug, it will probably run away from most 455s while they’re sitting there hoping to get traction.

[Skip Fix]

When I swapped a 400 short block under my RAIV heads that I had on a 455(NMCA changed the rules no RAIV heads on a 455) same cam. intake etc with the 3.42 gears the 455 used the 400 was a dog. It took 4.56s a looser convertor to run the same and feel the same.