Yep that's how you roll them.... the 15° get the extra 1° from moving the valve guide.

500rwhp I think is doable with what you are talking about in a motor with standard 23° head and a good intake to match..... actually one of the motors I am finishing up is basically this combination.

the 18X should be able to do 530-550rwhp.

Hell to me every "street" motor should go to 7,000rpm but they don't have to it's just nice.

Bret

 

Man this is killing me I need to get some cash flowing so I can get this motor together, lol


Bret, Why on Brodixs websight reccomond the 18x to have a compression of no lower than 13.5:1, that would be ruining the pump gas Idea right?



-john

 

Hey, glad I could help guys. The side-by-side really shows you the differences huh?

One thing I noticed that the 18x could use is real obvious in the chamber comparison. It needs a little deshrouding in the 3 o'clock - 6 o'clock position (intake side) and 6 o'clock - 9 o'clock (exhaust side).

Needs some profiling of the guide bosses. They're definitely beefy. And you can really see in the intake port comparo that the 18x still has quite a bit of doglegging, where as the 15º is a very straight shot... no compromise. But man... I think anyone with half a brain and a variable speed grinder could make the 18X into a mean flowing son of an 18º race head.

-Mindgame

 

Also from the Brodix website:

John it recommends that compression ratio to have some sort of low end, but honestly these heads are for a RACE CAR, hence the 4000-7500 powerband, and the "Oval Track / Drag Race / Pro Street" applications. I guess when the day ends it all comes down to who you want to believe, and who is building fast cars. You could believe Brodix or believe the theory master. I would honestly hate to see you waste your hard earned money being someone's guinea pig. Stick with a set of 23° heads more suited to your application

 

Wow ignorance is abundant..... You actually have to understand how engines work to get why this setup WILL work on a lower compression street motor. Hell single planes work awesome on street motors and they are all labeled for 4000-8000rpm. I must be dumb for using them on motors that only see 6500-7000rpm max; they should still allow the motor to pull to 8000rpm and completely die at anything below 4000rpm. Strange but that doesn't happen. Glad I didn't just go by the recommendations of Edelbrock.

Rule #2 applies here: "A little bit of knowledge can be a very dangerous thing." - My old man AKA OldSStroker

MG you think you can explain about your 15° street motor..... It’s not the only one out there but since you pulled it off and understand why it works then maybe you can explain it to the uniformed. Basically what I’m getting into next is one of the reasons why I feel you made a LT intake work with the port adaptors on your motor. The additional runner length in the heads and from the adaptor plates makes the overall runner length of your motor much better for performance.

Well the 13.5:1 recommendation is what would be in line with their RPM range recommendation.... RPM, Camshaft and Compression all play hand in hand. When you add cam duration to run a higher RPM you will lower the DCR so in turn you need to crank up the SCR. That's not a theory..... I have proven that time and time again but it's backed by an understanding of how things work, that's why I did what I did in the first place, it's not trial and error.

Hell they would work on a 9:1 restricted race motor as well..... If you have any doubts that shallow valve angle heads very close to these run 9:1 compression ratios just look up GM part numbers 24502569, 24502580 and 12370855. Those are actually the same castings (363) that MG has on his LT1.

BTW 13.5:1 can work on pump gas, DCR would be the first explaination of WHY it can. Hell the new 3.2L Audi V6 has 12.5:1 STATIC on 91 octane gas in a OEM application.

I could go into why the heads whoup all over the 23° CNC T1's and it's not just flow. I think that this says a lot:

23° CNC Track 1 227* 4700rpm, 588.1 Torque, 526.3 hp
Out-of-the-Box 18X** 4700rpm, 684.0 Torque, 599.0 hp

Yeah looks like that monster port is going to kill the low end. 100ft lbs! more at 4700! It's not 2500rpm but it is below TQ peak.

Let me explain one more time why these 18X heads are good street heads.... The ignorant don't read or understand my posts anyways so I might as well spell it out for everyone else to read. That's why I post here anyways so I can share what I know, and writing or verbalizing ones own knowledge actually helps ME understand things even better. Not like anyone who thinks I'm a moron would actually try anything I say out to disprove me.... They can always call BS but when it's time to **** or get off the pot well... shrinkage seems to happen.

The average port cross section comes into play here... and I've seen it cripple the Jeg's Kaase SBF heads as well in the eyes of the consumer. The average consumer is Joe Dumb ****... I hate to say that but it's true, hell that was a theory till we proved that in this thread as well. (Yes we all know I'm not talking about John here) Port volume is like LSA it's a dependant variable on other things that mean more in terms of what's actually going on but people like things to be simple when in reality they are far from it. Hell AFR knows this and that's why the AFR 215 RR is called a 215cc port when in reality it's a 230-235cc port, because it's LONGER! It just equates to a 215cc port if it was a standard 23deg head. Hell if the 18X can't be used on a street motor, the AFR 215's can't either.

The port length on the 18X is 5.7" long. This is the reason why the port volume looks so big.... To actually compare apples to oranges you need to convert the port volume to an average diameter or average cross sectional area. A 244cc runner that is 5.7" long has a 1.83" average diameter or 2.65 sq in average cross sectional area. In comparison the AFR 210 port that was lying on the table next to it was 5.125" long, 210cc and that equals a 1.78" average diameter and 2.5 sq in average cross sectional area. IMHO and from what I have proven 2.5 sq in is too small for an average cross sectional area on motors that will see 6500-7000rpm and are over 355 cubes. A 225cc port that is 5.125" long would actually work out about right on a 383 cube motor. BTW that works out to a 2.7 sq in average cross sectional area.

Now is that rule stead fast? No this is just a good rule for the average 23° casting out there.

The average cross sectional area is only part of it..... The next restriction in the port sizing is in the min cross sectional area which is in the pushrod pinch on a Chevy motor that doesn't use big offset rockers. Al la the 18X and most 23° heads. (AFR 215RR, AFR 227, All Pro 245RR are notable exceptions) Mindgame has posted the formulas for min cross sectional area requirements based on cubes and RPM for a motor... It's a good guideline but I have seen some really good heads do better than this rule so it's all in how you use it. You have to make sure your port is large enough in the small spots not to cause a restriction, the best way is to velocity probe the port there and get an effective min cross sectional area. That's a good term from Mr. Meaux. He finds good use in the effective area in porting heads for port volume limited classes.

After the MCA of the port is right for the application, usually you have to work on the Short Side Radius (SSR) of the head. A 23° STD port Chevy head is always going to have issues here because of the height of the short side, you can have way to high of velocity over it and it can actually be your choke point on the head. Raised Runner heads greatly help this, and it's another reason why the 18X is such a killer head. A nice SSR can actually help you run a smaller port than normal since you can control the velocity over the SSR better. So in actuality an 18X head can be made with a smaller average cross sectional area (ACSA) than a properly sized standard port 23° and gains in TQ and drivability will be found.

Makes sense now that someone can explain WHY something works and not just make unbacked regurgitated advice.

I wouldn't mention these heads if they were not going to work. I also doubt Brodix has seen lots of these heads on pump gas street motors. If you want to call Brodix John, lets do it in a confrence call so you can ask them whatever and I can ask the questions dealing with the application and you can hear both sides of this. The best thing is to have a head in hand to look at and measure.... been there done that.

Bret

 

Call it regurgitated, but honestly I don't want to see someone else spend thousands of dollar just to be disappointed in the end, and then land up parting it out because it didn't perform as promised

John call Brodix and talk with a tech guy there, they should be able to point you in the right direction

 

Jay you do fill in a good role here..... you act as a antagonist and that just gets me to post out why things work... You'll see Mindgames best posts are on one side of a arguement as well, and he always seems to be right as well.

Bret

 

Well I can tell you this much.... my buddy and I like to get together and play every now and then. He has a 97' Viper GTS with one of Roe's superchargers strapped on top... Ballenger headers, accufab tb's, mildly ported heads, Borla exhaust and enough torque to upset the rotation of the earth.

From down low I can take him all day long cause traction is a term this car knows nothing about... even with close to ~13" of sticky rubber on the road. My car is a little soft under 3k but guess what... that's not necessarily a bad thing on the street.
From under 3k I can roll on the throttle and overtake the GTS every time. If I want to get in the sweet spot real quick like, I take my 2200-2500 cruise rpm, drop it down a gear or two and roll on it to keep the traction. It'll pin you to your seat. Now that's not saying that the Vipe couldn't roll on and do the same, but the boost is just insane with this car.

So, I don't know how much more rwtq I'd really want with this thing. I'm running Nitto 315 DR's out back and they don't stand a chance under heavy throttle. Race head... or no race head... the car has more than you could ever use on the street. I don't doubt you could bolt a set of these 18x's on a street motor and do close to the same without a lot of cam. That's the beauty of it.
It's not for everyone but I guarantee you this... if you ever had doubts about building something like this it'd only take one short trip to change any preconvieved notions real quick. "Soggy bottom" is something for poorly matched combinations with low dynamic compression. Knowing that..... let's you build something of another caliber.

Superchargers and nitrous are too easy but people like them for the same reasons. Lotsa power when you mash the gas.

And yeah.... I don't mind a good arguement from time to time. Some people are thick headed (raises hand) but I want to know WHY you think I'm wrong and dad gummit, you'd better explain why. Why not? We ALL learn something that way.

Keep the peace (hippies).

-Mindgame

 

BTW John,
Not to rub salt in any wounds but... all that cool & expensive 18º stuff went for a dirt cheap $1575.

http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMEWA%3AIT

With deals like that.... who needs a stinkin 23º head?

-Mindgame

 

Mindgame/StrokerAce


Now what do you guys think of the slightly used Busch parts that are being sold through different vendors accross the nation? I have been doing alot of research on the Brodix 18X cylinder heads and the GM 18° cylinder heads lately, and this thread has become very valuable.

I have talked with a couple of engine shops down South, and I can supposedly buy a set of fully CNC ported GM 18° cylinder heads w/ titanium valves, fresh valve springs, Jesel or T & D shaft rocker system, 18° intake, basically a COMPLETE set of heads and intake for the price of around $23-2500.

Now would this be something to look into, or would it be easier to start with the Brodix 18°X heads? My main concern with the used older Nascar or Busch 18° stuff is that the port sizes and port cross sections wont be right for a 396ci, 12:1 compession motor (ie. some street/strip driving).

Thanks guys
Brian

 

Good thread!

Rich

 

Rich it's getting back to being a good thread!!!!

I'll like to see what MG writes but here is my take on it....

Most big time ports I see in 18° stuff have a MCA in the 2.7 sq in range.... If you plug that into what RPM that would work well on... then you are looking at a 7800-8000rpm 396. If you want to twist the thing then by all means its the way to fly. If you only want 7000rpm well then 2.4 sq in is a better number to look at. The Big 23° stuff is in this same MCA as well... and is for high RPM and big cubes. Something like this.... Jones All Pro 22° would be REALLY good on a 7000rpm 400 cube motor. (BTW Ron's Porting has something similar to that... and BTW I think this type of thing is where you will see Joe O going this year)

The hard thing with the normal 18° stuff is that they don't have a PR pinch point so they are not going to have a small MCA in that part of the port... it's either going to be very consistant cross section or the MCA is around the valve at that point.

The real deal here is that port cross sections in the proper range for what we are talking about here going to get you all about the same results. Most top of the line heads with cross sections in this range are all going to have about the same REAL flow numbers. Look at the Brodix 18X, HVH Brodix -10, Jones 242cc All Pro, Gen 230-10, Weld Tech Jones 240

They all are in the same flow range and MCA range... that says a lot. The 23° (and 18X) stuff is all raised runner and usually offset rocker shafts to get those numbers... Now take out the raised runner and the offset rockers and you are back to the 290-305cfm club... These 23° and 18° are the next progression if you want to get more numbers on the dyno. After that we are talking really about more RPM or some really exotic castings... My take is that the 18X is basically a street version of a 18° head. It will work better on bigger motors and you will want to turn some RPM with it, but if you go 18° and don't want a 7,000rpm SBC street motor, well then you are in the wrong game.

If you look at the heads MG linked they are BARE castings... Unless you are going BIG RPM and BIG Cubes (8,000rpm and 420 or more cubes) then this is the way to go, because then you can have a really good head casting needing not as much work and you can go pretty dam fast on it. That's the key get the castings BARE and go from there, even a GM 18° casting bare has lots of material for a street motor port.

We have a good thread about used Ti valves in here too.... They are much cheaper but in the end they might not be of the best use.

Bret

 

This thread has my head spinning.

 

Thank You, Mindgame, for stating so eloquently what i have been screaming for years.Not that i am in your league, but as a man putting 575+ fwhp to 245/50 16s;I say you speak the truth.Sure im a bit soggy down low[even with the girl grind i run now] but opposite lock at 55 is not the sort of thing i enjoy doing regularly, and more TQ wont help that.
I agree the cost is effective now for 18deg[thanks SB2], ive already got $1300 in my fast burns and if i cant find someone to max them with good #s im going 18. whats going to suck is the bill from Hogans for the custom piece to keep my flat hood. I dont give a hot damn on a cold wednesday if i give up power/tq anywhere under 3.5k, as i burn halfway through 2nd NA as it is, and if youre building anything other than an all stock or GM crate SBC, why should 7k revs be a problem for your hard parts on street motor?

I have thoroughly enjoyed the discussion/opinions on this thread[as many other topics in this forum], its the various opinions/facts/experiences/information that make this board a place of interest to a non-internet guy.


Oh, and Mindgame, Im on the hose BTW, its not my fault;i used to streetrace. But ive been to a few N.A. meetings [BAD pun] and am working on it.
Ill shutup now.

 

Man, I leave for 4 days and miss all the good stuff again!

All the cylinder head (and various rides/local shows) are posted here:
http://www.quarter-mile.net/rides/

Bonjour guys and keep up the good discussion.