44o gts dart
Well-Known Member
That’s definitely a good idea
906 or 915 ?
- Thread starter 44o gts dart
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That's no comparison. Either porter to crap and back or stock. Either way, IMO, the 906s win. But who gives a crap about making an iron head flow when there are aluminum offerings?
A dinosaur is a dinosaur no matter what the number. If I'm using a dinosaur, I'm using the closed chamber and building for quench
GO for it!
MopaR&D
Nerd Member
Even if they're "better" they still flow like a drinking straw for feeding 440+ cubes. Once I started learning about heads for other brands, stock BBM heads are pretty sad in terms of both flow and combustion chamber design. Eric Weingartner on YT ported and flowed some BBM TrickFlow 240s and he was like "yeah they're a lot better than stock but about the same as a mid-range aftermarket SBC head..." He also reviewed a set of Stealths and noted the terrible (in his opinion) chamber design of the stock heads where the valve seats have no angled ridge continuing the top seat angle for helping low-lift flow, basically like every other aftermarket head has had for the past 15+ years or more.
With that said I have a pair of Stealths myself I'm gonna have a valve seat job done with some other hardware upgrades (10 degree locks etc). I don't hate them by any means but I'm not going to deny they (and all stock BBM heads) have flaws. Also not worth getting too caught up on flow numbers and Brand X comparisons when guys like @IQ52 are pushing 700 HP with "crappy" stock castings. There are other factors at play like is always the case with Chrysler stuff lol. Might have to do with the bottom end geometry with the high rod length:stroke ratio? Idk, still learning myself.
Wait... we were talking about a 450-hp street engine. These threads always end up like this LOL my bad...
I don't disagree. I wasn't the one who started talkin about iron heads. lol
33IMP
Well-Known Member
As I understood this thread, the o.p. has a set of stock 906s, in unknown condition, verses buying a running set of ported 915s off a running ten second car.
I also understood they were going in a factory M-code 440 A-body, so aluminum heads are OUT!
Given the choice of dumping a buttload of money in a 906, or buying ported 915s in running condition, .....it's like a 2024 ticket of biden/fetterman. A true no-brainer.
I also understood they were going in a factory M-code 440 A-body, so aluminum heads are OUT!
Given the choice of dumping a buttload of money in a 906, or buying ported 915s in running condition, .....it's like a 2024 ticket of biden/fetterman. A true no-brainer.
The OP says stock looking with under chassis headers. This isn't a concourse restoration. So it seems there is some leeway in what happens to this GTS. Stock looking would even allow a stroker kit.
One thing to remember if 'stock looking' includes a year correct stock factory cast iron intake manifold, that manifold will limit airflow to around 200 cfm even if your heads flow 320 cfm. Yes, I've personally made that test.
450 horsepower isn't mild in my opinion, that is more like ripping. This thing is going to be more than stock to go 450 HP, or a stock HP 440 wouldn't be only 375 HP. 450 is going to be dangerous in a Dart.
Ah, what the heck do I know.
One thing to remember if 'stock looking' includes a year correct stock factory cast iron intake manifold, that manifold will limit airflow to around 200 cfm even if your heads flow 320 cfm. Yes, I've personally made that test.
450 horsepower isn't mild in my opinion, that is more like ripping. This thing is going to be more than stock to go 450 HP, or a stock HP 440 wouldn't be only 375 HP. 450 is going to be dangerous in a Dart.
Ah, what the heck do I know.
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Yup and the Stealth heads fit the bill perfectly. That's a crappy flowin intake.
44o gts dart
Well-Known Member
True ,,,, my head is spinning ,,,, I may need to flow test my head.. lol,,,, I had just heard the stealths have crappy review’s
@IQ52 (Jim Laroy) has made lots of power with them.
They had some problems when they first came out, thus the bad reviews in the early years.
The problems were resolved, but as with any aftermarket head they should be checked.
As I recall, Jim has a thread around here on the Stealth, he seems to like them as a lower cost head.
44o gts dart
Well-Known Member
Do they come with the right locks and springs?
Take a look at Jim's thread.
Pretty sure weingartner only flowed the 240s out of the box. I watched the same video. But yeah Mopar wedge heads are small ports but with the power a 240 or 270 can make it the blocks capabilities of handling the power. I'd say at the point of looking at an aftermarket block because of power concerns trickflow heads aren't going to be first choice, probably Indy's bigger heads, B1 or predator heads.
They come with light hydraulic flat tappet springs and 7 degree locks and chincy seals . Very common stuff.
I've worked a few, all I had to do was better the valve job, ream 1 guide and surface them minimal to dial in the compression .
PRH
Well-Known Member
I’ve owned a flow bench for 30 years.
That’s back when there were hardly any aftermarket aluminum heads for BBM available.
Long before RPM heads, and all the Chinese copies.
Back then porting factory heads was pretty common.
Thru the years I had many people send me their “home ported”(or heads reworked by a shop that didn’t specialize in porting and had no flow bench) to flow test them.
A typical ootb Stealth head flows 260-265.
With the seats recut and a proper bowl blend they’ll flow 280.
The heads people sent me to test were often in the 230-240cfm range.
On the very rare occasion I’d see something touch 260.
None were even close to 280.
I can tell you one thing for certain........ how pretty the porting might be........ is really not a good indicator of what they’ll flow.
Also, since MP always preached “don’t touch the SSR”, and most people took that to heart...... with regards to the 906/915 intake port in particular........ if you don’t address the SSR....... you’re never going to see big flow numbers from those heads.
That’s a long way to say........ if you don’t have the 915’s tested........ you don’t really know what you’re getting.
That being said, even if they only flowed 230’s-240’s....... if the overall curve was decent....... they’d still be fine for a 450hp type combo.
I did what I would consider an actual “porting” job(not just the bowls) on a set of big valve 906’s in 1990. That was the first set I spent that much time on porting some heads.
They made 535hp on a 448 with a RB SSH-44 cam.
A couple years later after I had my first flow bench I had the heads off and flowed all the ports.
They looked pretty........ but the 8 cylinder average was only 239cfm.
Like with many skills......”once you know” how to do it, it gets much easier.
Nowadays, I can get 260-ish out of a nice bowl blend, bull nose the guide a bit, and a SSR tweak.
Those 239cfm ports had the whole port reworked, all polished up, etc.
A lot of time for 239cfm.
That’s back when there were hardly any aftermarket aluminum heads for BBM available.
Long before RPM heads, and all the Chinese copies.
Back then porting factory heads was pretty common.
Thru the years I had many people send me their “home ported”(or heads reworked by a shop that didn’t specialize in porting and had no flow bench) to flow test them.
A typical ootb Stealth head flows 260-265.
With the seats recut and a proper bowl blend they’ll flow 280.
The heads people sent me to test were often in the 230-240cfm range.
On the very rare occasion I’d see something touch 260.
None were even close to 280.
I can tell you one thing for certain........ how pretty the porting might be........ is really not a good indicator of what they’ll flow.
Also, since MP always preached “don’t touch the SSR”, and most people took that to heart...... with regards to the 906/915 intake port in particular........ if you don’t address the SSR....... you’re never going to see big flow numbers from those heads.
That’s a long way to say........ if you don’t have the 915’s tested........ you don’t really know what you’re getting.
That being said, even if they only flowed 230’s-240’s....... if the overall curve was decent....... they’d still be fine for a 450hp type combo.
I did what I would consider an actual “porting” job(not just the bowls) on a set of big valve 906’s in 1990. That was the first set I spent that much time on porting some heads.
They made 535hp on a 448 with a RB SSH-44 cam.
A couple years later after I had my first flow bench I had the heads off and flowed all the ports.
They looked pretty........ but the 8 cylinder average was only 239cfm.
Like with many skills......”once you know” how to do it, it gets much easier.
Nowadays, I can get 260-ish out of a nice bowl blend, bull nose the guide a bit, and a SSR tweak.
Those 239cfm ports had the whole port reworked, all polished up, etc.
A lot of time for 239cfm.
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PRH
Well-Known Member
Of course, what hasn’t been mentioned here is....... for the novice “DIY’er”, the 346/902/452 heads are easier to get into the 260cfm range.
Primarily because the SSR is much flatter and easier to rework.
Most of the 906/915 home reworked heads that suffered from lackluster higher lift flow is almost always because of a poor form on the SSR.
And those heads are pretty fussy about what the right shape is.
This spring I went thru a set of previously reworked 906’s.
Done at a shop with a flow bench and a dyno.
Bowls were opened up a bit more than I would have for std size valves, but almost nothing done to the SSR.
Peak flow of [email protected]
Primarily because the SSR is much flatter and easier to rework.
Most of the 906/915 home reworked heads that suffered from lackluster higher lift flow is almost always because of a poor form on the SSR.
And those heads are pretty fussy about what the right shape is.
This spring I went thru a set of previously reworked 906’s.
Done at a shop with a flow bench and a dyno.
Bowls were opened up a bit more than I would have for std size valves, but almost nothing done to the SSR.
Peak flow of [email protected]
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44o gts dart
Well-Known Member
Very nice,, very informative,,,, btw what ssr?
33IMP
Well-Known Member
Short side radius. The bottom of the port, just above the valve.
44o gts dart
Well-Known Member
44o gts dart
Well-Known Member
So if I just put bigger valves in the 906’s seats for unleaded fuel ???
44o gts dart
Well-Known Member
No,,,, probably just paint a nice dual plane orange,,,gotta have some flow
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