L-35 heads.

[It's just a six]

Re: L-35 heads.

http://www.syty.net/forums/showthread.php?t=79029&highlight=lb4+heads

Thanks for that.:tup:

The heart shaped chambers are supposed to decrease the tendency of detonation, by having more of a quench area, but if your pistons are down the hole, that does not help much.
Not sure what our engines pistons deck heights are, most likely they are down the hole as a guess .010-.020"?
Anyone?
When Josh, A.K.A Tooky installed his 96 & newer Vortec heads, he did not think they suppressed detonation any better than his stock heads.

The LS series engines have positive deck height & part of the reason they can run higher compression.

I'm having my ported L35s drilled out for bronze guides and if the vains are solid I'm going to remove them and re flow the heads

Thanks for the pics. :tup:

As to your question, I have been wanting for someone to find a junk L-35 head & see if the vanes are solid, if they are I would definitely remove them, it is an obstruction, they (the vane) were made for low speed torque, not for high RPM.

As far as your bowls look, they look like any typical SBC head not a flat wall as a member hear posted they are.

What P.N. are you heads? 181's?

 

[proptop]

Re: L-35 heads.

Just a six,
PM me contact number so I can call you. As I do not want to get in a debate about porting heads on line. But the other fellow is right, taking out the vane is a waste of time on these low rpm (stock motors). I am going to use l-35 heads on my motor also. I should have taken pictures of them before the motor was put together.
Thanks,
Bob

 

[It's just a six]

Re: L-35 heads.

proptop,
thanks for the offer, but if there is proof that taking the vane out does not help, I think as a group we should talk about it here & discus the reasons it works or does not work.

I am not talking about a non turbocharged engine here. I have heard from my friend that owns a cylinder head shop that a customer removed this vane & it helped him tremendously & that was on a N/A engine. He raced his truck with the vanes removed, some spec class racing, not just a daily driver ride.
No proof mind you, just a rumor sort to speak.
But why would a guy lie about that? He was not trying to sell his heads, just passed on info of what worked for him. Gear heads talking about cars, engines etc.

So if you could point us in the right direction as to where we can get some more info, great.

Also, if you have before and after flow numbers when the vanes were removed, that would be great info also..

Thank you.

 

[It's just a six]

Re: L-35 heads.

Just thinking out loud, it's not as if GM designed these heads for turbocharged applications.

They are basic heads designed for low engine speed to help improve off idle acceleration & provide low RPM torque, they do just that, very well.

They are just Astro van heads if you will, not designed for any real HP.

Then the 96 & newer Vortec heads were produced, there is no high swirl vane intruding/bottle necking the intake port, why?, mainly they opened up the port volume, vastly improved the short turn radius's & most likely changed the valve angles & throat angles, just me thinking out loud, could be wrong about the 96 & newer Vortec heads, I have not studied/ dissected them or read up how the heads have changed, this is just my observation of looking at the 96 & newer heads comparing to the old school SBC heads. The V-8 Vortec heads are the same design as the V-6 heads , 96 & newer.

If any of you guys have ever driven the 1988 -1995 Chevy/GMC V-8's you guys know what I am talking about when I say those do not make any upper RPM power, the heads are the same as our LB4 heads, junk.

I stated before, since we have turbocharged engines, basically making as much torque as we need to blow up out 700R4's, we can afford to increase the airflow of our cylinder heads & gain more upper RPM power.

I have not seen a back to back comparison, when a Sy/Ty was running stock LB4 heads & installed a set of stock 96 & newer Vortec heads.

Both combos been tuned as best as possible & see the ET's differences. Anyone seen this?

It is obvious the 96 & newer Vortec heads are better designed heads, they have no high swirl vane in them, yet they produce the same or more power for our applications.

I am hoping we can prove that by removing this bottle neck vane will greatly improve our HP & ET's.

I know the 95 350/5.7 SBC made 200 hp IN 1995, crappy head, plain hyd tappet cam, throttle body injection (2 big injectors)

In 1996, the Vortec engine came out, more compression, multi port FI, hyd roller camshaft
& of course the vastly improved Vortec heads.
This engine made 255 HP w/all these changes. I currently own a 1997 Silverado truck same engine 5.7 250 HP.

My truck is no hotrod by any means , but it is much quicker than the older 1988-1995 Chevy trucks.

Good reference posts http://www.syty.net/forums/showthread.php?t=95956

I'm done for now.:roll:

 

[Snoman002]

Re: L-35 heads.

I too am interested in a back-to-back stock head vs. Vortec head dyno comparison. I hear about vortec heads as being THE head mod, but couldn't find any comparisons showing the difference (same truck, just a head swap).

BUT, the 95-96 head difference... Yes, the 96+ make more HP, but its a minor improvement and mostly a trade off, IMO. Just like the 3.5l Colorado motor makes more HP than the 92 TBI motor, but the TBI more made insane torque just off idle, try and say that about the 3.5l. Its realitivly easy to move power around, but to truely make more everywhere is much more difficult. Heck, TBI to CPI, the TBI was a 160hp stump puller, and the CPI was a 200hp rever, yes it made more HP by moving the torque curve up, but it just moved the torque curve, it didn't really MAKE much more power.

So the question is, torque or HP? HP is fun, and can be a benifit in drag racing, but the rest of the truck has to be tuned to truely use it (high stall, low gears, etc). Street use, well you have a hard time convincing me the loss of low end torque to make high end HP is worth it.

 

[It's just a six]

Re: L-35 heads.

All those comparisons are with N/A engines. We are turbocharged.

On a N/A engine, you port the head too much, or install a much larger cyl heads, you lose port velocity, meaning you lose low end torque, but gain more in the upper RPMs.

I do not believe enlarging the intake port is really going to hurt our turbocharged engines, after all, they are just GM production heads w/an intake port volume of what 160-170 CC's ? then we are enlarging the intake port volume to 230 CC's (the size of some larger aftermarket heads) because we are thinking about removing this vane, no, the intake port volume is only going to increase the cc's very little.

As far as comparing the older TBI to CPI, the TBI was a 160hp stump puller, I do not know the history of there 1/4 miles times, but I am pretty sure the 96 & newer 4.3 Votec headed trucks were faster, all things being equal 3:42 gears etc, ,, but like I said, I did not follow the 1/4 mile time on those vehicles, so if that is the case, the newer Vortec 96 & up heads has to be a major role as to why they are faster?
Are the 96 & newer 4.3 trucks finely tuned, so that's why they are faster?
Is there combo perfect, w/gearing, torque converters, headers, bigger exhaust etc, etc.? No, it's just a basic truck for anyone to jump in & go faster in than the older trucks.
HP does not break the drive train, torque does.

The Vortec 96 & newer heads, are much better heads than any stock production GM ever produced,, there was not any SBC head that would outflow them, nothing from the 60's 70's 80's or 90's standard style heads I am talking here, maybe some reverse coolant flowing LT1's were close, (not including LS heads) but I do not think so.

I would like to get my hands on a L-35 head, see if in fact the vanes are solid & take/grind it out port it & bench flow it. (mind you, grinding the vane out is a lot of work)
So if anyone hear has a junk L-35 head they would like to donate to the cause that would be great.
I know how to port, they would not the prettyiest, but they will flow much better than a stock head.
All the polishing as in port & polishing, the polishing is just for cosmetics for the most part.

I also have friends that do port heads for a living, so I can always get help, get hands on good reference cylinder heads.

Or, if someone here wants to grind out this vane, & post pictures showing it can be done, that would be great also & a start to possibly get an L-35 head to flow much better.

As far as thinking we would be giving up torque over HP, I just do not see it that way, if we need more torque, turn -up the boost some.

I, as well as most stock Sy/Ty's are a bit afraid to race from a roll, why, well because we do not make the HP the later model cars do, our MPH are almost always down compared to higher HP cars. I know all wheel drive, frictional HP loss etc. I would just like to MPH better than my current combo has to offer.
I know I can get there (more MPH) with more torque, but I am pushing the limits pretty high right now as far as torque is concerned. I am all stock 100%, stock long block & drivetrain.

I have only lost a raced on the street to GSXR 1000, beat the hell out of him out of the hole, but it passed me about the 1/8 mile. Surprised, no, disappointed no, it takes a great rider on the street to beat my truck out of the hole. Most street riders do not know how to launch hard or they just can't, they spin the rear tire, or wheelie,, both bad for quick launches.

BTW, These are just my views & thoughts. I do not take it personal if you disagree w/me, this is just a topic here so hopefully we can all learn from it. Weather your views are different, that's fine. post away.

 

[It's just a six]

Re: L-35 heads.

Just an update about my friends stock LB4 heads.

He said I can have them & cut them/port then as I please.

So I could work on those & see if there is any potential/truth about those heads being able to flow good.
Note: This is not going to happen over night though, I have a family & takes up most of my time. Just an heads up.

 

[proptop]

Re: L-35 heads.

Just a six,
Count me in I will donate a 064 head for our little test (by no means is it junk). What are the board members wanting to see? I would suggest one chamber pocket ported, one chamber full port with vane intact, and one with vane removed. Also what valve size would you want to use. If my heads were not on the motor ready to be installed . I would have one flowed and taken apart for pics. PM me your contact info and we can work out the details.
Thanks,
Bob

 

[It's just a six]

Re: L-35 heads.

proptop ,

rewind here for a second, did you say this on a previous post? " But the other fellow is right, taking out the vane is a waste of time on these low rpm (stock motors"

Not trying to sound harsh, but why the change of interest? Was it something I posted? I hope some of the things I said made some sort of sense?


Just curious.

 

[It's just a six]

Re: L-35 heads.

Just a six,
Count me in I will donate a 064 head for our little test (by no means is it junk). What are the board members wanting to see? I would suggest one chamber pocket ported, one chamber full port with vane intact, and one with vane removed. Also what valve size would you want to use. If my heads were not on the motor ready to be installed . I would have one flowed and taken apart for pics. PM me your contact info and we can work out the details.
Thanks,
Bob

Bob,
First off, thanks for stepping up.:tup:

when you say chamber pocket ported, are you meaning un-shrouding the valves in the chamber? or?

Or are you meaning bowl porting?

As far as valve sizes, a 1.94" stock size & up to 2.00" You really are not going to get much more flow running a 2.02" valve, but you will more likely have cracking in the chamber between the valves, there just is not enough meat/material when using 2.02 & 1.60" valves.:2cents:

Exhaust 1.60". if we are going to do that port also?

Can you post some pics of your 064 head? If possible.

The possible problem using your head is that removing the vane, you might ruin the head if the vane is hollow. We do not know if it is hollow or solid. That is the big question.

I am going to use my friends stock original Syclone LB4 heads & see if those are hollow or solid vanes first off.
BTW, these heads I am getting from my friend have been seasoning in his backyard for several years.:rotf:
So they will have a lot of rust. That's OK, educational poses right?

 

[Snoman002]

Re: L-35 heads.

All those comparisons are with N/A engines. We are turbocharged.

They work the same, there is just a higher pressure differential in a turbo motor. In a N/A motor the air isn't being "pulled" into the motor, it is being pushed in just like in a turbo motor. the only difference is the pressure differential is higher on the turbo motor, that does not mean the air will act totally different though.

On a N/A engine, you port the head too much, or install a much larger cyl heads, you lose port velocity, meaning you lose low end torque, but gain more in the upper RPMs.

I do not believe enlarging the intake port is really going to hurt our turbocharged engines, after all, they are just GM production heads w/an intake port volume of what 160-170 CC's ? then we are enlarging the intake port volume to 230 CC's (the size of some larger aftermarket heads) because we are thinking about removing this vane, no, the intake port volume is only going to increase the cc's very little.

That is not the whole story. Making the port larger likely will cause a loss in torque, but it doesn't guarantee an increase in HP. Point being, vortec head design (starting in 1987, it was in 1996 that it was marketed as "Vortec" and printed on valve covers) tricked the airflow to the outside of the valve, this caused the air to enter the valve at a slight angle, increasing flow across the valve instead of running dead straight into it, and caused greater airflow towards the unshrouded side of the valve, this provided better flow while still retaining high velocity.

As far as comparing the older TBI to CPI, the TBI was a 160hp stump puller, I do not know the history of there 1/4 miles times, but I am pretty sure the 96 & newer 4.3 Votec headed trucks were faster, all things being equal 3:42 gears etc, ,, but like I said, I did not follow the 1/4 mile time on those vehicles, so if that is the case, the newer Vortec 96 & up heads has to be a major role as to why they are faster?
Are the 96 & newer 4.3 trucks finely tuned, so that's why they are faster?
Is there combo perfect, w/gearing, torque converters, headers, bigger exhaust etc, etc.? No, it's just a basic truck for anyone to jump in & go faster in than the older trucks.
HP does not break the drive train, torque does.

You missed my point, it wasn't about TBI (LB-4) vs CPI (L-35) in the 1/4 mile it was about power delivery. The CPI itself didn't make that much more torque than the TBI, but its peak torque was much higher (260 at 3400 RPM vs 235 at 2000 RPM). The CPI motor couldn't really PULL any harder than the TBI motor (torque is the only force applied, HP is not a force) but because it was at a higher RPM it made more horsepower. In the end, all else the same, the CPI would win the 1/4 mile (by a bunch) but the TBI would take it off the line. In the end I was trying to make two points, one HP or 1/4 mile times doesn't equal driveability and that although technically the CPI motor made more HP it didn't make (much) more power over the TBI, it just moved it around to give it more HP. One last thought though, if you take two motors, with XX torque, one with torque at the bottom and one with the same amount of torque at the top (area under the curve being the same) and both can run to the same RPM, they will be identically as fast even though one makes more horsepower. Torque is the only thing that moves a vehicle, and is the only thing a motor produces.

Now, I apologize, the above comments are a bunch of jumbled ideas and knowledge that I cannot put to writing. Bottom line, making more power is truely hard to do, moving the same power around to different RPM's is much easier. By porting the L-35's you may not make more power, just move it up some, that means your truck will be slower on the bottom end and faster at the top.

The Vortec 96 & newer heads, are much better heads than any stock production GM ever produced,, there was not any SBC head that would outflow them, nothing from the 60's 70's 80's or 90's standard style heads I am talking here, maybe some reverse coolant flowing LT1's were close, (not including LS heads) but I do not think so.

I agree, I think the "Vortec" heads are great, I'm especially keen of the kidney shaped combustion chambers!

I would like to get my hands on a L-35 head, see if in fact the vanes are solid & take/grind it out port it & bench flow it. (mind you, grinding the vane out is a lot of work)
So if anyone hear has a junk L-35 head they would like to donate to the cause that would be great.
I know how to port, they would not the prettyiest, but they will flow much better than a stock head.
All the polishing as in port & polishing, the polishing is just for cosmetics for the most part.

I also have friends that do port heads for a living, so I can always get help, get hands on good reference cylinder heads.

Or, if someone here wants to grind out this vane, & post pictures showing it can be done, that would be great also & a start to possibly get an L-35 head to flow much better.

Please don't get me wrong, I would love to see this and wish you the best of luck! I'm not trying to poo-poo anybodies plans or ideas. If I had a set of heads to give you I would, at the very least just for the community knowledge gained.

As far as thinking we would be giving up torque over HP, I just do not see it that way, if we need more torque, turn -up the boost some.

Can you control boost by RPM? Because if your at max boost at high RPM's, you can't just crank in another 2-3 PSI at low RPM's to get back the torque you lost.

I, as well as most stock Sy/Ty's are a bit afraid to race from a roll, why, well because we do not make the HP the later model cars do, our MPH are almost always down compared to higher HP cars. I know all wheel drive, frictional HP loss etc. I would just like to MPH better than my current combo has to offer.
I know I can get there (more MPH) with more torque, but I am pushing the limits pretty high right now as far as torque is concerned. I am all stock 100%, stock long block & drivetrain.

Just remember, HP is a fictional number, you only gain HP by making MORE torque, or by applying what torque you have for more RPM. Plus, your driving a brick, air resistance is exponential, so 100 MPH takes 4x as much force to overcome as 50mph, 16x more than 25mph. Don't discount low end torque here either, racing from a slow roll is all about low end torque, not HP. In this the AWD and the automatic is your friend as well, most cars just can't get moving the way a SyTy can so it takes them a bunch to make up the gain you made in the first 60ft, but thats just traction. Sloppy converters can help too, but thats just because it puts your motor closer to peak torque. Tight converter and high low end torque or loose converter and higher torque, its all the same as the wheel speed and torque are matched with either. But tight converter and high end torque and your dead, or sloppy converter and low end torque and you just gave up your best acceleration.

I have only lost a raced on the street to GSXR 1000, beat the hell out of him out of the hole, but it passed me about the 1/8 mile. Surprised, no, disappointed no, it takes a great rider on the street to beat my truck out of the hole. Most street riders do not know how to launch hard or they just can't, they spin the rear tire, or wheelie,, both bad for quick launches.

Perfect example of torque moved high into the RPM range to get high HP, and giving up high torque numbers for high HP. I ride sport bikes and the torque is pitiful, but because I can apply a little bit for a LONG RPM range I get super high HP. Why does that make them fast if torque is they only thing that moves a vehicle forward? Because they can apply a little bit for a LONG time, and that means they get the advantage of low gearing for a LONG time too. I personally ran my SV1000 at 11.6 and 128 mph, but I was still in 3rd gear, thus I still had torque multiplication due to my gear reduction at the end of the 1/4. The end effect, I'm slow out of the hole but I can keep that acceleration rate up for a LONG time.

BTW, These are just my views & thoughts. I do not take it personal if you disagree w/me, this is just a topic here so hopefully we can all learn from it. Weather your views are different, that's fine. post away.

Well said!

 

[It's just a six]

Re: L-35 heads.

The main thing I am trying to point out about these high swirl vane heads, is that there is a bottle neck in the intake ports, it is these high swirl vanes.

Now, if you can remove this restriction, thus opening up the intake port window, it is going to allow more fuel & air into the chambers.

If you can allow the engine to take in more air & fuel, it is going to make more power across the board, not just higher RPM.

Think of your engine trying to breath from a small air filter, it will not breath well & will not make much power anywhere in the RPM band.
Take the same engine & give it a big air filter (no restriction) it is going to make more power everywhere in the entire RPM band.

Picture the intake port with the vane as a small straw of 1 square inch, the engine is not going to be able to breath well with only a port of 1 square inch, now , remove the vane, now the intake port is 1.5 square inches, the engine is going to breath a lot better.

Point is, I see the vane as a restriction, others seem to see it as creating more torque, which it does, but @ the cost of making more HP through out our minimal RPM band.

Here is an example of how our engines are limited by the stock high swirl LB4 heads.

First dyno I did I had a 20G turbo w/a 12 CM turbine housing. It made 386 HP @ 21 PSi of boost. 450-500 ft lbs of torque. Going from memory.

Last dyno I did, same 20G turbo, but w/a 60-1 compressor wheel & running 25 psi of boost. It made 396 HP & 600 peak ft lbs of torque.

The peak high torque figures are from the torque converter multiplication factor.

I see a big restriction going on here, by adding 4 more PSI it only gained 10 HP, torque went up a bunch more though.

 

[Icarus-54]

Re: L-35 heads.

Alright I'll try to enlighten you again.The roof of the intake port(lb-4--l-35)is flat,so there is no short side drop.Which means that the air -fuel goes over the valve head flat and only flows out the back of the valve so it saturates the back of the combustion chamber,thats the reason for the ramp.L-35's can be opened up to about 190+ cc's(carefully).Major gains can be had in front of the valve guide and cutting the diameter of the guide boss itself.You keep saying that we have turbo motors,yeah,but do you run in boost all the time?I think not.I've been doing heads since the mid 60's and have probably done over 15 sets of l-35's and god know how many lb-4's.The ramp is a good thing if treated right,you get really get good fuel distribution in the combustion chamber with it.And since its obvious that you've never worked on or looked at a set of those heads you might want to take some advice.L-35's make probably the best street and strip head because of that design,however as I've said they can be radically improved with a little common sense.

 

[It's just a six]

Re: L-35 heads.

Alright I'll try to enlighten you again.The roof of the intake port(lb-4--l-35)is flat,so there is no short side drop.Which means that the air -fuel goes over the valve head flat and only flows out the back of the valve so it saturates the back of the combustion chamber,thats the reason for the ramp.L-35's can be opened up to about 190+ cc's(carefully).Major gains can be had in front of the valve guide and cutting the diameter of the guide boss itself.You keep saying that we have turbo motors,yeah,but do you run in boost all the time?I think not.I've been doing heads since the mid 60's and have probably done over 15 sets of l-35's and god know how many lb-4's.The ramp is a good thing if treated right,you get really get good fuel distribution in the combustion chamber with it.And since its obvious that you've never worked on or looked at a set of those heads you might want to take some advice.L-35's make probably the best street and strip head because of that design,however as I've said they can be radically improved with a little common sense.

Thanks again for this info.
Questions, have you removed the vane completely? Are they hollow or solid?

It sounds like you have only done flow testing on these heads & have not offered any customer feedback for us to learn from.

Just because a head can flow great on a flow bench machine, does not mean it will work great in a street of drag racing application, correct?

If you have removed this vane? (big question) have you had them on a turbocharged engine & did direct comparisons, back to back test, 1/4 mile, 60 ft , anything et wise , between your massaged L-35 heads with & with out the high swirl vanes?

If you have flowed tested these L-35's in question, what did your massaged L-35 heads flow with & with out the high swirl vanes?

These are some of the questions that are not answered here.

As far as being in boost all the time? no, we are not in boost all the time, but when we are in boost, are we making more power with or with out these high swirl vanes?
These "Q's" need to be found out.

As far as been porting heads since the 60's , if your ideas about porting has not evolved then we are only having a limited point of view.

If you look @ how heads were ported in the 80s' they are different then how they are porting now a days.
The short turn radius's used to be sharp & not a large gentle radius. Better for higher RPM engines, but not good for an everyday street car.


I get most all my info from my friends head shop, & I do not all the answers & they do not either, but it gives me some good basic knowledge of what works & what does not.

 

[Snoman002]

Re: L-35 heads.

I'll try and keep this post short (sheesh that last one was a diatribe).

I know what your saying with the straw, but that's not the only part of it. I can guarantee that with a proper opening shape and a proper exit shape I can get MORE flow out of a smaller tube than an unaltered straight cut larger tube. And that smaller tube is going to have higher flow AND a higher velocity, this in the world of intake ports the best of both worlds. doesAir crazy thing, and quite frequently small things can make big differences just by tricking air into not getting into its own way.

My guess is that ramp is part of what makes a vortec head a vortec (again, introduced in 87, not 96). By pushing air to the outside of the port it gives it a better shot at the valve (not straight on) which improves flow through the valve and improves swirl in the combustion chamber.

 

[It's just a six]

Re: L-35 heads.

So, what you are saying is that you can get an smaller port L-35 head to outflow a not high swirl vane 96 & newer Vortec head? There is no obstruction in the 96 & newer Vortec head.

The Vortec head I am talking about is 96 & newer not an 87 Vortec head.

A little notch near the seat of the intake port is needed to improve the airflow on some LS style heads, IIRC, as much as 10 CFM increase from a little notch.
Maybe something like that would help our L-35 heads?

One of the main reasons why the 96 & newer Vortec heads flow more is because of the large short turn radius's. The L-35, LB4's old SBC heads have crap for a short turn radius. They are also larger in volume larger intake ports.

Keep it coming guys, this is good!:tup::tup:

 

[Snoman002]

Re: L-35 heads.

Picture the intake port with the vane as a small straw of 1 square inch, the engine is not going to be able to breath well with only a port of 1 square inch, now , remove the vane, now the intake port is 1.5 square inches, the engine is going to breath a lot better.

My point was that with a proper shape a smaller 'straw' can outflow a larger 'straw'. Air does funny things and often times tricking it one way, stalling it on one place, leading it in another can get it to do what you want, more so than just making the opening or cross.section bigger. Unfortunately air has to make a nasty turn to get into the cylinder and tweaks and tricks can make that happen more efficiently. Its not about the area or cross.section but also about how it makes the turn Not to mention that how it enters the cylinder can have a big effect on how it ignites and burns. Heck, theoretically less air in a cylinder can make more power (to a very limited extent mind you).

I'm not trying to poo-poo your idea, but your description just seems overly simplistic. It sounds more like you saying that this thing is in your way, cutting it out will make it better. We are just saying that its more complicated than that. GM didn't design that vane into the port, and then take it out and end up with the Vortec heads.

 

[It's just a six]

Re: L-35 heads.

My point is, by cutting out this restriction, increasing the cross sectional area, it should be able to to pack more air/fuel into the chamber. Maybe over simplistic, but maybe you are making it more complicated than it is?

GM's design are all designed for a naturally aspirated engine, not a turbocharged engine. I believe there is a difference, you believe there is no difference on cyl head design. Lets agree to disagree.

Why did GM take out the vane in the 96 & newer Vortec heads? Why do we not see this vane anymore in any GM heads?
I believe Nascar where producing high swirl cyl heads (in the 80's) & GM tried to do something similar, not sure though.?

 

[Icarus-54]

Re: L-35 heads.

What you're talking about is what's called "Drainpipe mentality",the bigger-the better.That doesn't al
ways work.The 2 most important things about porting heads are volume and velocity(pressure).The quest is to find the right balance between the 2.First of all is that heads only flow on a flow bench,in a running motor they pulse.Every time the valve opens and closes the pressure changes in the port and that's the same if you're in boost or not.When the back pressure and intake pressure equalize is when you will get sheeting or puddleing.The determining factors to intake size are bore,stroke,valve size and cam,both lift and duration.What you're attempting to do is drainpipe your heads,put a set of Brodix -10's on a completely stock motor and see how good that works.I really don't know what else to tell ya,but since you're so determined to be right,go ahead and do it.

 

[jeepruby04]

Re: L-35 heads.

Vortec

Pics of my L-35's. These are off an SGT. I'm having them pocket ported. My engine guy said he doesn't like the vane but has never completely removed one. HUGE difference between these and Vortecs. If I was going for all out power then it's a clear choice for Vortecs, but I'm just looking for a little increase and still want to keep the EGR.