experts: converted brodix 18x on LT1

I want an 18 degree head and from what I can see the 18x is the way to go. Easy 500+ rwhp got my attention, and from the sound of it it wont take a huge cam to get there on motor. I'm aware that there is obvious machine work involved to convert these heads to work on the LT1. I have a few questions about the conversion though.

1.) where can I get my pistons flycut for 18x heads?
2.) I realize the ports are higher in the 18x head than on a regular LT1 head. I have a complete accel superram for an LT1 that I want to use, that's getting extrude honed. Anyway I can adapt this so it fits/ fits better on the heads, maybe with some intake spacers? If I do that, how do you seal the gap on the front and rear walls of the lifter valley? How much of a raise are we looking at (cowl clearance is an issue with the LT1 SR)
3.) Any problems you can see with coolant passages in the head when drilling and tapping for the steam line? Do we know the size of it?
4.) Just confirming, all the LT1 valvetrain components (except the pushrods I guess) will work? I know the website says that they do, just want to make sure.

I found a few old posts regarding the 18x, but they didn't have exactly the answers I was looking for. I was going to convert and install a stroked 400 in my car and put these on it but I dont have the engine done yet, and I wont for awhile. U can see what I mean in some posts that I have made regarding a 434 with a custom LT1 timing cover, electric pump with spacers and other conversion work. I was going to have my 3.8" stroke crank lengthened to 4.0", but for the money, I think it's better spent on a 400 instead instead of messing up a perfectly good engine.

I'm planning on upgrading to 42# SVO's from my 30's, portmatching, retuning, upgrading to a 58MM TB (from my 52), and adding splayed main caps to my stroker while it's out in preparation for the 18x's. Is there anything I'm missing here?

I want an 18 degree head and from what I can see the 18x is the way to go. Easy 500+ rwhp got my attention, and from the sound of it it wont take a huge cam to get there on motor. I'm aware that there is obvious machine work involved to convert these heads to work on the LT1. I have a few questions about the conversion though.

1.) where can I get my pistons flycut for 18x heads?
2.) I realize the ports are higher in the 18x head than on a regular LT1 head. I have a complete accel superram for an LT1 that I want to use, that's getting extrude honed. Anyway I can adapt this so it fits/ fits better on the heads, maybe with some intake spacers? If I do that, how do you seal the gap on the front and rear walls of the lifter valley? How much of a raise are we looking at (cowl clearance is an issue with the LT1 SR)
3.) Any problems you can see with coolant passages in the head when drilling and tapping for the steam line? Do we know the size of it?
4.) Just confirming, all the LT1 valvetrain components (except the pushrods I guess) will work? I know the website says that they do, just want to make sure.

I found a few old posts regarding the 18x, but they didn't have exactly the answers I was looking for. I was going to convert and install a stroked 400 in my car and put these on it but I dont have the engine done yet, and I wont for awhile. U can see what I mean in some posts that I have made regarding a 434 with a custom LT1 timing cover, electric pump with spacers and other conversion work. I was going to have my 3.8" stroke crank lengthened to 4.0", but for the money, I think it's better spent on a 400 instead instead of messing up a perfectly good engine.

I'm planning on upgrading to 42# SVO's from my 30's, portmatching, retuning, upgrading to a 58MM TB (from my 52), and adding splayed main caps to my stroker while it's out in preparation for the 18x's. Is there anything I'm missing here?


1. Any compotent engine builder can handle the pockets

2. Yeah, you'd need spacers to correct the port alignment. You'll need end rail spacers to get the proper gap.

3. The coolant line? I used -6AN with a 1/2" threaded fitting.

What kind of rpm will you be turning? Are you planning to use the stock PCM?

-Mindgame

If ya use a 400 SBC ya won't need to convert them.
I am confused about the steam holes(400SBC in the head gasket area) and the conversion. A 400 SBC is not reverse cooled and the heads don't need converting and to my knowledge ya can't run the LT1 water pump. The timing cover might fit with mods but why-- when ya can run a dual sync dist and still retain the computer and EFI.

Are you talking a stroked LT1 here? or a 400SBC?
Ya can't take the 400 block and run it in place of the LT1 block and bolt the LT1 stuff to it and try to run it as an LT1 it ain't reverse flow cooled. Haven't heard of anyone converting the 400 block to reverse flow either or if it can be done.

I've done it. lots of little custom stuff though. I did it ona 406. Haven't hadany time to invest in that little project lately though.

Looking to spin up to 6500 rpm as my shift point. Im looking for power to kick inaround 2000 though. I want some brutal power over around 4000 or so, so I dont mind having to spin the thing a little higher to get it if I need it.

Biggest thing is I need to do is figure out how to put the superram on the 18 degree heads. Lingenfelter has done it, but they stopped developing on the LT1, and nobody there remembers what parts were used or how it was done. But they got close to 600 rwhp and tq with a SR equipped 18 degree headed sbc and thats close to what I'm looking for out of it.

And yeah, I'm looking to use the stock PCM... at least until I can afford to get a good DFI unit anyway.

SuperRam with 18 degree heads?

Kinda like sauerkraut and chocolate. Just doesn't seem right to me.

Everything I've ever seen from Lingenfelter (magazines, books and shows)... he would use an 18 degree head and build a custom intake with a front mount LT5 throttle body. I honestly don't believe a SR could be opened up enough to fully compliment a halfway decent 18 degree head.

-Mindgame

That's what I was thinking...but I asked some questions about abrasive media porting the superram, and I was told to expect around 270cfm or more per runner through a superram. Kinda makes me wonder if it's worth it since the heads I flow now run up to 277 on the intake side. I've also been debating just going with the single plane too, I just dont want to give up the midrange grunt.

MG,
Good analogy.

irocz,
If you are worried about midrange grunt...maybe you should purchase a peanut port big block? Or maybe this is the time to quit the car thing and pickup a hobby like needle point?

I don't mean to be abusive, but if you want results compromises must be made. If everything is correct, revs don't matter. Like I tell my sportsman racers, the tach is the most evil thing in the world it will make you worry about things that don't exist.

Remember: Torque = energy displaced. Horsepower = energy displaced over time (work). I like motors that work!

If it was all about midrange and low RPM displacement, we would be racing 9" stroke diesel motors.

Concerning the conversion of the 18x, the brodix stuff is some of the worst cast aluminum in the industry. Make sure you have someone very experienced in welding these heads. If you are going through all of the trouble, I don't know why the 18x is even a contender.

I have much info on the subject. I have converted a couple heads here and there :p

if you would like, PM me or call me in the shop. Oh, and like MG said - the superam is great for holding small marine objects in place for long periods of time.

torque wins races too. Torque makes a car more fun to drive. What's your point? With horsepower comes torque and vice versa, but I'm not racing...I'm trying to enjoy my car.

The 18X head will take most of my valvetrain stuff and flows well and comes in plenty of different configurations and is closer to aa street friendly head. Not too concerned about the alloy being 'worst cast' if it doesn't fatigue, crack or fall apart easily, which I haven't heard of.

I had a SR on an old TPI motor once. That intake kicks ass. Far better than the LT1. Just a PITA to work on. I'm not sure if I want to take the plunge with a single plane just yet, looks kinda pricey to do it right. Not to mention with 18 degree heads the thing is going to want to pop out of my engine compartment so I'm going to need a cowl hood. I'll probably port the SR and stick with the LE3's until I get around to having money to do the whole thing at once.

Not too concerned about the alloy being 'worst cast' if it doesn't fatigue, crack or fall apart easily, which I haven't heard of.


The guy doing the welding for the conversion probably will be concerned w/ the quality of the casting..

torque wins races too. Torque makes a car more fun to drive. What's your point? With horsepower comes torque and vice versa, but I'm not racing...I'm trying to enjoy my car.
I believe it's w/ torque come's HP.. Not Vice Versa.. :D If you gear the car correctly you'll have what you want where you want it.. I dont' know to many people who race even stock car's as low as 2Krpm dyno pull's don't start till 3-4K.. So get a plan, talk to those that have built what your looking for.. and then go from there.. :)

The guy doing the welding for the conversion probably will be concerned w/ the quality of the casting..


I believe it's w/ torque come's HP.. Not Vice Versa.. :D If you gear the car correctly you'll have what you want where you want it.. I dont' know to many people who race even stock car's as low as 2Krpm dyno pull's don't start till 3-4K.. So get a plan, talk to those that have built what your looking for.. and then go from there.. :)


Very nicely said, Steve.

I am :D It's not HP that I'm looking for, though alot of it would be nice. I can't speak of what other people do when they race because like I said, I'm not looking to race for the most part, I'm looking for more torque. I'm thinking that because of the large valves I may hold back on the 18x heads until I get a bigger engine to replace the 383 now so I'll be more in the sweet spot. What I like about them is even though they're 245cc's, the runners are also longer, so it's kinda like having a 210cc head so I dont loose as much torque, especially with a bigger engine.

I dont want to have to rev the car just to make driving it a gratifying experience. Not looking for just low end tq either or I'd build a TPI motor, looking for midrange. I know HP comes with RPM, and I know that 18 degree heads have been used in conjunction with a superram, so I'm trying to explore all my options before doing one thing or another. Problem is, how many people have you seen on the board use anything other than a single plane with 18 degree heads? Much less a miniram or a superram?

...and by saying torque comes with HP and vice versa, I meant you can't have one without the other. Just depends on how you build the engine as to where and how much you have of each :cool:

Torque by definition: moment of a force, force required to break the absence of rotation.

So, My question is how are we winning all of these races when we are not moving? Horsepower is the measurement of rotational torque .. per say. The freak magazine editors have so much of the population brainwashed into creating new definitions for words that have been around long before cars!

How many times have you read "tire boiling torque!". This torque must have a burns-o-matic...because I have never seen a tire, while sitting still, start to erupt into a molten boiling mass, unless heat was applied.

for the displacement you are talking, you are already out of the ballpark as far as the induction system is concerned. How your posts are worded, it sounds like you want these components, even if the car makes less power than it did stock!

I'm not here to sell you anything but information. What you do with it is up to you. I just hate to see you build the worlds most expensive turd known to man. each to his own though.

Good Luck

I just hate to see you build the worlds most expensive turd known to man. each to his own though.

Hey!!! That's my job...:D

Problem is, how many people have you seen on the board use anything other than a single plane with 18 degree heads? Much less a miniram or a superram?
Are you just out to put somthing together that nobody else has? If so i can sorta understand your idea.. Original, non-bandwagon or run of the mill setup's.. Am i correct?

But on the other hand you don't have the avg joe blow lt1 guy trying to guide you.. Most the old timer's on here such as SStroker,Oldssstroker,Airflowdevelop,Mindgame these are all folk's that know what they're talking about.. They are not trying to push you one way or the other nor are they pushing any one brand of heads. They just give you the info and let you run w/ it.. maybe i just reitterated what dennis already said.. But there is no need to go on defensive.. Especially in this post where other's can learn due to the common ?'s most have about converting any set of Gen 1 sbc head's to be used on a LTx.. Just learn.. :)

MG,
If you are going through all of the trouble, I don't know why the 18x is even a contender.




I always thought it was a good head?! :confused:

I always thought it was a good head?! :confused:


heh. You said "good head". :D

Ask MG about his TORQUE to go along with his 760-780FWHP. Bet it's in the HIGH 6's maybe low 7's.
OBW what ya gonna do with THAT much torque on the street without 17 x 33's. 400RWHP is uncontrolable on the street without DR's anyway.

I know--- ya can put a 2.50 gear in it with a glide with a 1.76 first gear.:shrug:

Ya could get a set of 227's or convert a set of Pro Action heads and have ALL ya want. Except for a trailer queen or ya are MG(MG got toy's) 600FWHP and 550 ft lbs of torque from a 383 will get the job done on the street. After ya learn how to drive that,put a 300 shot of hose on it and really run up the tire bill. This can be done under 7000RPM's with Noooo problem.
That much torque will pull your 30'ChrisCraft anywhere.

True. Good points. I'm not looking for so much torque that I can burn out on the interstate...and I am looking 'outside the box' for solutions to things I would like to improve on (IRS and 400+ci for example). Like I said, for the most part I spend 95+% of my driving time down low in the powerband, so when I replace my intake and bump up the compression (it's at 10:1 right now :eek: ), I'll put in a smaller cam too to compliment the SR.

For the 18X heads, I think I'll wait until I get a bigger engine in there than the 383. I'd love to put the 18 degree heads on it now, but dont have the time or money to go with a single plane, and the reduction in cam, SR, and increase in compression should take care of the low end problem. I'll probably put in a set of 3.73's from the 3.42's, but since I have an M28 T-56 I'm not trying to go too low on the gearing either.

I like what I see in the 18X's because of the price, 23* compatability and specs on the heads (not being outrageous or racey). Anything I'm not seeing here?

True. Good points. I'm not looking for so much torque that I can burn out on the interstate...and I am looking 'outside the box' for solutions to things I would like to improve on (IRS and 400+ci for example). Like I said, for the most part I spend 95+% of my driving time down low in the powerband, so when I replace my intake and bump up the compression (it's at 10:1 right now :eek: ), I'll put in a smaller cam too to compliment the SR.

For the 18X heads, I think I'll wait until I get a bigger engine in there than the 383. I'd love to put the 18 degree heads on it now, but dont have the time or money to go with a single plane, and the reduction in cam, SR, and increase in compression should take care of the low end problem. I'll probably put in a set of 3.73's from the 3.42's, but since I have an M28 T-56 I'm not trying to go too low on the gearing either.

I like what I see in the 18X's because of the price, 23* compatability and specs on the heads (not being outrageous or racey). Anything I'm not seeing here?


A set of Pro Actions can flow in the 330/340 range. Convert them and ya GOT 600fwhp IF the rest of the engine is done right.
They will cost ya about $3200.00 ported and sprung up and ya "could" run an LT4 intake (not the best ,but).A set of offset shaft rockers and a good mechanical roller with Crower or Isky pressure oiled lifters with no offset will get the job done.
Put some hose on top of that and--- well it would be fast and pretty driveable.Ya wouldn't want to go to California in it but it would be fine for short trips.

heh. You said "good head". :D

I have a way with words! ;)


There's nothing like it, is there?!:D

.

So, My question is how are we winning all of these races when we are not moving? Horsepower is the measurement of rotational torque .. per say. The freak magazine editors have so much of the population brainwashed into creating new definitions for words that have been around long before cars!

Good Luck

This torque vs hp stuff has been around for years. To settle this in my mind, I went to web pages of professional engine builders/racers like Reheer Morrison looking for dyno sheets and also studied dyno sheets of cars that I know that for some reason are particularly fast for their combo or peak hp rating.

In my mind anyway (subject to change) it all about gearing, converters and average hp within the intended rpm range. Gearing multiplies torque.

This torque vs hp stuff has been around for years. To settle this in my mind, I went to web pages of professional engine builders/racers like Reheer Morrison looking for dyno sheets and also studied dyno sheets of cars that I know that for some reason are particularly fast for their combo or peak hp rating.

In my mind anyway (subject to change) it's all about gearing, converters and average hp within the intended rpm range. Gearing multiplies torque.......but it doesn't multiply horsepower.

Your mind is right, DM.

I've never built a max effort street car that I thought needed more "low end torque". However, I do know a number of people who have a problem with too much. They have to be very creative with the throttle to accelerate quickly on a ~12" wide radial tire. ;)

And forget launching from a dead stop cause it isn't going to happen unless you're in Fast & the Furious dimension, where cars wheelie with no burnout AND spin the rear tires. :)

Cruising around at 2k rpm... it's no problem getting into the sweet-spot. That's what they made downshifting for.

A SR and an 18 degree head would be the perfect example of a mismatched combination if ever there was one. Put a single plane on there (preferably a model with enough plenum volume for your big cid) and go have fun.

-Mindgame

...but it doesn't multiply horsepower.

Your mind is right, DM.


Don't confuse me or I'll change my mind.

Don't confuse me or I'll change my mind.

"Indecision...the key to flexibility."--Anon.

i don't think a motor with strong low end that runs out of breath at top end is fun, but to each his own.

Happy reading :)

http://web.camaross.com/forums/showthread.php?t=282514&highlight=18x
http://web.camaross.com/forums/showthread.php?t=188680&highlight=18x
http://web.camaross.com/forums/showthread.php?t=333037&highlight=18x
http://web.camaross.com/forums/showthread.php?t=369346&highlight=18x
http://web.camaross.com/forums/showthread.php?t=359678&highlight=18x