377 SBC build

[HQM383]

It will not get anywhere even close to 500 bhp until the heads are ported generously.

What's the mcsa of those heads?

[F-BIRD'88]

It will not get anywhere even close to 500 bhp until the heads are ported generously.

What's the mcsa of those heads?

Somebody smart may know this.
Irreguardless these as cast heads will need generous porting to get the intake and exhaust port flow up enough to make a real deal 500bhp.
260 cfm in. 200 ish ex. or more.

Its up to you the end user to finish the job Flotek started.
As cast typical sbc aluminum heads are a start point.
They all need porting.

[skinny z]

From the Flotek website.

sbc_200_flow_png.png

What's with the 4.3" fixture bore?
That's even sillier than RHS and the 4.2" bore they used to sell their old line of iron heads.

[F-BIRD'88]

From the Flotek website.


sbc_200_flow_png.png


What's with the 4.3" fixture bore?
That's even sillier than RHS and the 4.2" bore they used to sell their old line of iron heads.

This is after porting. No as cast out of the box.
I bet they are not more than 245cfm in.

[skinny z]

From the Flotek website.


sbc_200_flow_png.png


What's with the 4.3" fixture bore?
That's even sillier than RHS and the 4.2" bore they used to sell their old line of iron heads.

This is after porting. No as cast out of the box.
I bet they are not more than 245cfm in.

While I believe it's the as cast version (although I can't say I can verify that) the fact that they're tested on a (to me) ridiculous 4.3" fixture bore only serves to inflate the results.
I was in a discussion here on ST to assess the results of my RHS heads which RHS advertised as tested on a 4.2" fixture. This obviously skewed the results to the large side and I was looking for some data to correlate 4.2" testing vs a more conventional 4.03". None was really provided although going through Stan Weiss' data base for head flow, one could draw conclusions.

That said, I understand the significance of using flow bench to determine the viability of a cylinder head. As HMQ pointed out by way of asking...

What's the mcsa of those heads?

...there are other values of importance that would also serve to determine any heads given potential.

[HQM383]

What's the mcsa of those heads?

...there are other values of importance that would also serve to determine any heads given potential.

Correct. That was highlighting mcsa as a segway to discuss what other elements of a port have to be assessed to determine their potential output capabilities. As you pointed out the flow figures should be taken with a grain of salt from Flotek as there maybe a fudge factor there. The mcsa can’t be fudged so there is one fixed factor that can indicate potential. 200cc means nothing in the way of potential either and I’m sure you will agree. So for the OP where I was going with the mcsa is “take your heads to a professional to be assessed if they are capable of your requirements, if not then what needs to be done”. They may need no more than a quality valve job and some tidying up. The old “get ‘em fully ported” doesn’t really give the OP much direction, which I'm sure he has come to ST to find.

[skinny z]

An interesting observation from an enthusiast such as myself (and by definition I'll say enthusiast is one who does this racing thing recreationally) is that when putting all of these pieces together regarding cylinder heads, or more specifically my cylinder heads, is that knowing the MCSA, port volume, CFM, throat diameter, etc. and also having addressed a few of the basic porting fundamentals that for my build ( I can't stress that my enough) is that it all comes to a fairly defined point. That point would be realizing the potential, not hoping to exceed it, but using all that's there.

My new cam went into production today (Or will be once funds are transferred. Thanks Mr. Jones) and the cam designer wanted CFM specs. OK.
Others here have discussed the MCSA and how it relates to potential output. OK.
Still others have published papers suggesting that for a given CFM, the smaller the port the better so as to enhance velocity. Also OK.
Then there are those in that rarified air that can examine these parameters in minutiae and have there opinions based on analysis. (Witness the latest CFD thread!)
Then there's the intake manifold, carb, et all.
Headers and exhaust arrangement via PipeMax etc.
(I've been slapped around for it but dammit, I find sims useful and informative.)

None of this has taken into consideration how the chassis figures into all of this but that's a tale for another time. It's the lump that's the topic of conversation here.

Anyway, after having all of that sorted out: heads, cam, intake, exhaust, (even the oil pan and windage) the hope is to reap the rewards of having all of the bits working together.

If the OP wishes to make 500 HP, it'll pay dividends to examine all of those parameters so as to ensure success in achieving the goal.

[steve cowan]

We can even take a step back and look at valve size to bore ratio.
4.165" bore with a 2.08" intake valve.
With a 2.02" valve it is similar to my 383 - 4.030 " with 1.94" intake valve, they can be made to run ok with a smaller valve.

[levisnteeshirt]

I've never heard anyone say that built a 377 ,, " I hated how that motor ran " ,, usually people like em.

I did a budget 383 for a dirt racer ,, 13.5-1 ,, 220 RHS heads ,, 633 gear ,, 3400 lbs ,, I asked him if he would rather change the gear or the cam ,, he said gear ,,, so I put the Isky 304 mega cam of old in it similar to yours ,, he said it was pulling hard to 7500 and still felt good at 8000 ,, anti pump lifters zero lashed valves ,,, so that's a healthy stick you have in that 377 ,, needs RPM/gear and at least a 4500 stall IMO ,, especially with that low of compression

[af2]

With that cam and it’s .600” lift and those out of the box 200 Cc heads I can’t for the life of me see why you can’t make 500 Hp.

3 months ago I did a old set of Trick flows getting them to 260@ .500” for use on a 364 purly street SBC going in a fully loaded 65 B body.

With 10.25 comp and a cam of 218/226 , 462”/ .470 on a 112 the motor made these numbers well below 6000 rpm.

The intake was a Victor jr 2 bbl that I modded to take a 4 bbl.

Apples to cherries comparison..

[Tom68]

I've never heard anyone say that built a 377 ,, " I hated how that motor ran " ,, usually people like em.

I did a budget 383 for a dirt racer ,, 13.5-1 ,, 220 RHS heads ,, 633 gear ,, 3400 lbs ,, I asked him if he would rather change the gear or the cam ,, he said gear ,,, so I put the Isky 304 mega cam of old in it similar to yours ,, he said it was pulling hard to 7500 and still felt good at 8000 ,, anti pump lifters zero lashed valves ,,, so that's a healthy stick you have in that 377 ,, needs RPM/gear and at least a 4500 stall IMO ,, especially with that low of compression

Only down side to a 377 is keeping the bores round.

[levisnteeshirt]

I've never heard anyone say that built a 377 ,, " I hated how that motor ran " ,, usually people like em.

I did a budget 383 for a dirt racer ,, 13.5-1 ,, 220 RHS heads ,, 633 gear ,, 3400 lbs ,, I asked him if he would rather change the gear or the cam ,, he said gear ,,, so I put the Isky 304 mega cam of old in it similar to yours ,, he said it was pulling hard to 7500 and still felt good at 8000 ,, anti pump lifters zero lashed valves ,,, so that's a healthy stick you have in that 377 ,, needs RPM/gear and at least a 4500 stall IMO ,, especially with that low of compression

Only down side to a 377 is keeping the bores round.

No different than a 406 etc etc ,, I've saw some 18 degree 406s back in the day with a production block run good for a couple years without problems ,, some people are lucky,, some people aren't,, I had a 406 that got hot 1 time and it smoked and used oil afterwards,, I didn't think it got that hot ,, theory was the cylinders egg shaped and wore the rings uneven,, just a mild street motor in a Vega around 1982

[skinny z]

I've never heard anyone say that built a 377 ,, " I hated how that motor ran " ,, usually people like em.

I did a budget 383 for a dirt racer ,, 13.5-1 ,, 220 RHS heads ,, 633 gear ,, 3400 lbs ,, I asked him if he would rather change the gear or the cam ,, he said gear ,,, so I put the Isky 304 mega cam of old in it similar to yours ,, he said it was pulling hard to 7500 and still felt good at 8000 ,, anti pump lifters zero lashed valves ,,, so that's a healthy stick you have in that 377 ,, needs RPM/gear and at least a 4500 stall IMO ,, especially with that low of compression

Only down side to a 377 is keeping the bores round.

No different than a 406 etc etc ,, I've saw some 18 degree 406s back in the day with a production block run good for a couple years without problems ,, some people are lucky,, some people aren't,, I had a 406 that got hot 1 time and it smoked and used oil afterwards,, I didn't think it got that hot ,, theory was the cylinders egg shaped and wore the rings uneven,, just a mild street motor in a Vega around 1982

Many years back my machinist advised against using an over-bored 400 production block. In a pile in the corner of his shop were two or three blocks that had cracked from one of the head bolt holes to the cylinder. Not sure what the cause was other than, as stated above, some people are lucky, some aren't. Sonic testing I would think would have revealed any potential weakness but my discussions with him never went much further than that. I did my first of many 350's after that in my second go round of hot rodding.
On a similar note, speaking of luck, one of my earliest SBCs (first go round 45 years previous) was a 400 I sourced from a scrapyard office floor. Standard bore that was refitted with rings and bearings and off I went as a happy teenager racing that thing every chance I got. A dropped valve ended that one though.
Such is luck.

[prairiehotrodder]

my rule of thumb with 400 blocks is try and go .020 instead of .030 as a starting bore size when using an old factory block. My 377 i mentioned earlier eventually cracked a cylinder after about 5 years of a kids abuse.

[rgalajda]

Good points about those heads.
That cam doesn't belong in a street driven vehicle ,period. In fact, it's too much cam for those heads/engine even for a strictly strip car.
Cam should be about 290/235 max, not 314/252