fixing the WORST ENGINE DESIGN I've ever encountered

I still don't know why GM designed this intake manifold the way they did, but today, we're gonna fix it permanently, and the right way. When we're done, we should have a bump of about 20 horsepower, and eliminate some problematic issues with the PCV system. However, there's a good chance we might ruin this intake manifold (inadvertently) as part of the process. In the name of power and speed, we're cutting apart a perfectly good intake manifold in hopes of making it even better, but if we can't weld it back together, we'll be out of luck.
my temporary PCV fix on this manifold last year
• this is the WORST ENGI...
Check out Raylar for 8.1 parts. he can do the same modify a stock intake or you can purchase the Gen7R intake as well.
www.raylarengi...

[@RAWRMotorsports]

Ive seen other ppl preheat cast with a prepo torch to help burn the impurities out b4 welding

[@TheTruthBeToId]

Yeah ive seen it done also especially in pipeline welding.

[@ClumsyCars]

You preheat cast and let it cool slowly to prevent cracking when welding on it

[@jmillshobbies6344]

Yes when i was at tech one of my instructors was telling us if you have to weld cast preheat and a trick to let it cool slowly you could bury it in some sand for a few hours

[@gibbeys]

Most of what is being discussed applies to welding cast iron. It really does not like the welding process and is prone to cracking if the heating and cooling is too sudden. The biggest issue with welding aluminum cast or otherwise is cleanliness and heat. Dirty aluminum is almost impossible to weld. Large/thick pieces dissipate heat quickly so without preheating it’s hard to get good welds. Conversely it’s really easy to burn through thinner aluminum with good heat control. Getting good welds ( on any material) requires practice. Just my experience.

[@MrTRAVELER96]

Great idea hopefully. I hope it works out. I will however suggest wearing a respirator while grinding aluminum. There is a lot or theories that ingesting aluminum by breathing it or ingesting it by using using aluminum cook wear causing alzheimer's disease. Also I noticed that he was not masked while spray painting. Please don't take it as criticism. just advice from an old man that is blessed with good health after doing this kind if work for 60 plus years. Please take care of your lungs.

[@scottg391]

I've done a few cut and gut and the easiest way is to chuck it up in the old Bridgeport and whack the bottom off of the entire unit from front to back roughly an inch from all sides. This gives you plenty of room to clean up the ports and plenty of room to weld on a new an improved bottom. I'd fabricate the bottom cover from 3/16 plate which has a 2"drop in the front with a sweeping radius that follows the intake runner and taper it to the back of the unit to smooth out the airflow. This mod with Stock heads a comp 46-422-9, shorty headers and high flow cats and exhaust, 42lb. injectors and a proper tune, makes 460 HP and 500Tq at the wheels. (4L80E trans) The stock manifold with all the other modifications would loose about 30 hp-tq and the engine would lay down around 4800. Time and money well spent over the Raylar bucks up unit. I don't care what anyone says about the Gen IIV, they respond very well to just a few modifications and are pretty much bulletproof. As you will attest to. Great content, always fun to watch another Gen IIV sucker working on this junk.

[@beetlebuilder5882]

When the intake is modified, does the engine lose any bottom end torque? I use my truck for towing and wouldn't want to lose power on the bottom.

[@madprops526]

I'm not a "welder" but maybe back purging with gas on the inside would help. I also saw something about preheating with a torch to warm up the surrounding metal and to burn off any impurities. Love what you do and so glad you moved to colorado. You inspire me and I'm sure many others.

[@deltaalphalima4759]

Typically you don’t back purge aluminum. Titanium and stainless need it though

[@noobFab]

Once you get the truck back together I would love to see a comparison between a stock intake, your modded intake, and the Raylar

[@sammontiforte7472]

Me too. I don't even know why he is messing with this one compared to the raylar?

[@BBCMONTE34]

It’d be cool to see an egt/afr on each cylinder with stock intake compared to the modified one.

[@Scandalous3pedals]

Man I wish you would wear PPE for your lungs LT. Especially with aluminum dust. Keep up the awsome work

[@joshuaelizabethfoster6276]

Glad to see you got around to this. I prefer brazing to welding cast aluminum. Heat guns are way more reliable on heat-sapping metals. Hope you get at least 15 of the maybe 20 horsepower this mod can net.

[@DTunedMotorsport]

My first cast repair job went the same way… turning up the “cleaning action” or AC balance ends up putting a lot more heat into the TIG torch. Fried the torch by welding for too long and ended up in the same boat. Do your welding in smaller spurts if you don’t have water cooling for your TIG setup.

[@imonaroll9502]

Harbor freight has a small cutoff wheel. Works great on getting in those small spaces.❤

[@Bacongrease00]

I think this is a pretty common mod on the intake. You got it! TFS has some good videos on doing this type of stuff. Seems like his technique was to bring the junk to the surface using the AC balance. Would be interested to see the street 8.1 motor get forged pistons and rods and head studs eventually

[@QMarais95]

Hello. I remember when I was a child, reading an used car advice magazine, with reports of many oil consumption issues on GM-made Opel models. I guess it was common in the period the Vortec 8100 appeared. Concerning the weird intake airflow design, I am sure the engineers who made it wanted to add some intake legnth to turn the engine torqueier at low-end range, as it was supposed to be put on utilitary vehicles. A shame the manifold looks like a pressure loss trap.

[@edlebrock3501]

im pretty sure the reason chevy design the intake that way was to help balance air pressure and displacement across all the runners from the center out instead of the front runners taking priority and making factory tuning easier. Good mod for Boost though!

[@gordowg1wg145]

Yes, you beat me to it. Having it underneath would also reduce fuel drop-out as the engine would heat the transfer passage, pre-heating the port air*, and it would aid bonnet (hood) clearance. * I expect they're still port injected, as DI would be a MAJOR redesign issue.

[@philbert006]

For being hesitant, it came out beautiful. Certainly it will balance cylinder availability of air and probably spool faster. Solid gold man!

[@abnpthfdr2934]

That was a ballsy move you did there with opening up that intake. I think it will pay out, big time!!! Can't wait to see the ugly truck running again!!!

[@roaddoglv]

Nothing wrong at all with that weld job.🔥 Looks like with all these big blocks time to buck up a couple of level from the HF stand. The 2x4 is a nice touch, good work around.

[@CS-oe8og]

LT, I know I didn’t examine that weld, but what I saw looked good. Great video.

[@seancollins9745]

that shelf is there to make the air distribution more even across the cylinders. this is what a limited plenum volume gets you. So you should make that underside plenum as big as will physically fit. make the plenum go deeper into the lifter valley and then build a tin oil splash shield to keep the oil off of it.

[@chevyfan82]

My experience is limited with cast aluminum but I've found that once the part starts getting hot porosity became more of a problem because the heat was releasing contaminates deep within. After dealing with that a few times I found that pre cooking it to help burn out the oils embedded deep into the casting. But still believe in letting it sit and cool down rather then burn it all in at once. Nice job 👍 looking forward to seeing what the 8.1 will do with the mods.

[@BLKMGK4]

Looks like Richard Holdener may be getting ready to delve into BBC intakes too!

[@ReshardsAutomotiveWorkshop]

You are teaching me what to do before I get started. 😊👍 I'm so glad you are doing this. I have an 8.1 that I am swapping into a square body Chevy.

[@Danno74Z]

Hi LT, Instead of welding the cast aluminum why not use JB Weld to cold weld the two pieces back together again. Plenty strong enough for your application after curing for a few days and no leaks. Heat it's and issue nor chemicals.

[@bluecollarhotrods9781]

What about the other end of the tube? Guessing that it didn't need to be sealed off?

[@tylerward9277]

I was thinking the same!

[@Beefdup]

Pretty sure he is going to use that tube as part of his PCV setup. I could be wrong, but it is convenient. That or he will blind off the original EGR port and not worry about it.

[@privatedata665]

The welds look great from my couch in Pennsylvania . Cool Content

[@mikeo5668]

Awesome job! I can't wait to see what these changes bring on the dyno!

[@erichildreth7562]

This looks great! Can't wait to see it running again!! Nice work LT!!

[@shemwhitehead9517]

A purchase I highly recommend: a Bridgeport mill. It doesn't have to be Bridgeport brand, but it will facilitate so many custom parts and parts modifications. And of course, make sure to get a good vise and clamp set. P.s. a digital readout is a must as well.

[@LawrenceTolman]

Agreed! My wish list absolutely has a 3 axis mill and a lathe at the top of it

[@yrboogiemn]

Reminds me of welding my Saturn's cast intake manifold for ITBs. Fun stuff and very stressful. But once you get it done right, it's a sigh of relief. Plus, yours won't ve visible. Function over form.

[@DaInfamous0ne]

Loving the builds. I want to make my S10 blazer a awd monster. I might have to bring it to Colorado from Tennessee. 😁

[@brian2359]

Looking good! Glad to see a busy shop!

[@LawrenceTolman]

Thanks 👍

[@Techangler65]

Looking forward to the grand Cherokee build. As with all your videos great job. Stay focused on the small things

[@petersouthernboy6327]

No, you NEED to get that involved, Tolman !

[@brucemitchell5637]

When i was building aluminum boats we used to refuse to weld on cast aluminum lower units on stern drives and outboard motors because of all the impurities and sand that were in the castings. It was about a 50/50 chance of getting a watertight decent weld and the custwould literally want us to warranty it for as long as they owned it!

[@414Chevy]

Disregard my last transmission. Should get you another 20-30 NA HP, probably 50 on boost. Good job!!!!!!!!!

[@justatim8143]

JB Weld will work if you can't weld the cast aluminum but preheat may help. Weld looks good and I can't see it from my house.

[@davidtappe5337]

love cutting stuff up. Good job LT, welds are nice.

[@noreastermike1621]

It might be time to invest in some welding curtains. The one guy in the background covering his eyes.

[@ValarAmstaffs]

Getting closer!!! Great video, LT!!

[@LawrenceTolman]

So close!

[@kona5853]

Just some extra ideas if you did this again. I’ve done this in manifold repairs Instead of welding cast you could mill each side flat. depending on the wall thickness to determine hardware drill and tap. use tapered cups machine hardware m4 m4.5 or m5 and use permatex. Under boost it could be questionable would require some extra hardware (to accomodate pressure) but na applications it would work pretty well.

[@theautoanswerman8063]

It would be awesome if you compiled a parts list and modifications done to get this engine to this level.

[@jackmagnium6115]

hi lawrence. ok so i have finally decided to draw your truck with all the suggestions that i had given you(not sure if you remember) and been a bit busy on other projects. i hope to god i have this done in 2 weeks or less

[@jaayg9262]

Almost there keep pushing LT💪💪

[@skuz34]

i still have my fingers crossed that the race chassis is going to get a denali body put on it, big block denali sounds sick as fuck to me! besides i think the 01-06 denali front end is one of the nicest GM has ever made

[@arthurrodesiler3109]

If you spray the cutter and the part with WD 40 really helps the cutter from clogging up. They may have better stuff now but thats what i used 30 years ago.

[@ThomasTT496Vega]

Sounds like the new project will be the same truck im building. Syclone-clone. Im using, Twin turbo 6.0. 4L80E, NV149, ford 8.8. 14 inch C6 brakes and 6C wheels on all 4 corners. Got the front diff out of a Bravada with the GT4 optional 3.73 gears that match the 8.8.

[@bobqzzi]

Love these videos GM: millions of dollars of R&D using multimillion dollars computers, CFD software, dynos, and other test equipment. Hotrodders: I have an angle grinder, sawzall and welder. Appreciate the fearlessness, but I'm doubtful you've improved airflow, and may have negatively affected distribution. Has someone done dyno tests on this?

[@LawrenceTolman]

According to his website, Raylar has verified this on the dyno. Plus, Richard Holdener has backed up these claims with a similarly modified intake on his channel.

[@bobqzzi]

@@LawrenceTolman Very cool then.Nice job on the welding BTW- factory cast aluminum is tough to do.

[@joesilvasr9733]

Come on now, that welding job turned out pretty darn good IMO.

[@TheTruthBeToId]

Weld looks great and no one is gonna see it anyways so you good. Btw that intake is crazy restrictive for such a big bore engine.

[@B4Ctom1]

I am literally giddy and cheering as you cut this thing up to make it useful.

[@jacobmonroe209]

Interested to see what the hp/tq numbers with be at the same boost levels the previous setup ran.

[@mvpolo2k3]

They did that design for even distribution to the cylinders, the air entering the center of the plenum made sure all cylinders got the most balanced amount of flow. same reason they have that big cylinder in the LS intakes.

[@BBCMONTE34]

I would think by removing the baffle, airflow will prefer to go to the front cylinders.

[@mrgmc6314]

That is a very large possibility ...

[@mewrongway]

Hit it on the nail head!! Unlike Ford when GM does something there is a good reason! 👍👍

[@mathieusynnott8915]

lovin your video minus the grinding leaving the sound😂

[@kevinschmidt9295]

Dont be so hard on ur self, ur learning and besides it looks good to me!! let her buck!

[@ThomasTT496Vega]

I like your work LT!

[@scotttimpany2845]

Nice work LT.

[@69JJV]

When are you testing the new Raylar 8.1 intake? I need to see some real world test other than theirs. Commented before I saw your Raylar Intake still would be nice to see this on this engine. Is it over kill for a stock engine. Would be great to see your modified on this engine to the Raylar.

[@gabriellindig]

I'm starting to get the feeling you don't like welding cast aluminum for some reason...🤣

[@LawrenceTolman]

Haha… truth

[@sammontiforte7472]

I hope you sale turbo and exhaust header kit when you done with it. I want turbo on my 8.1.

[@rustloversgarage]

This is good stuff!! Great video man!!!!!

[@Broadpaw_Fox]

At 13:18 - you showed that you sealed up the one end of that tube you cut out, but what about the other end? Does it connect into the intake plenum as well? IF you don't close that up, aren't you going to have a massive vacuum leak?

[@LawrenceTolman]

The other end just goes out toward the back of the intake where it passes outside with a block off plate. It’s no longer connected to a vacuum source (that got welded up), but could be used as part of the PCV a system if needed.

[@Broadpaw_Fox]

@LawrenceTolman - ah, got it. From the video we couldn't see what/where it connected, so it was worth asking. Thanks for answering!

[@henrybrundage7186]

Life happens have fun and don’t sweat the small stuff ( by the way it’s all small stuff!)

[@user-qy1tw8kc8e]

Is there a video of how you did the pcv? I would guess a catch can is in there somewhere.

[@teaguegearhart9851]

A lot of hard work to get it nice and clean. But hey gotta get it done the right way.

[@davidhorsley1149]

Just an opinion; by removing that "shelf", as you called it, I would think that you killed both air velocity and vacuum signal in the plenum. Though you did enable a greater volume of air to flow through, that increased volume would only be beneficial at sustained high RPM. Plus, by only removing the front "shelf", rather than opening the whole lower half of the intake as the other manifold, I would be concerned about air restriction to the back four cylinders. The two considerations that may cancel these concerns is, 1, your mentioned forced induction, and 2, the fact that it is a fuel injected engine, so you're only moving air through the plenum. It would be my assumption that unless you are reving north of 7-8000 rpm's, or have bored and stroked the engine off of the charts, that you may have killed that intake for streetability. I don't even know if that mod would be beneficial to a dedicated street/strip vehicle. Look forward to updates and the outcome of that mod on a street sleeper.

[@mrgmc6314]

So my father in law bought a 2500 avalanche about 10 years ago , this summer he was in a accident in the truck , so he bought 2 more one for parts and one for a temporary replacement for his original one , he is gifting me his temporary replacement and were going to pull the motor , transmission , transfer case , computer , drive shafts , and a few other odds and ends ,from the parts truck, thoes extra parts will either go to future repair or we will be building a ugly truck or car like you have to swap the extra 8.1 and a big turbo .... I also have a sierra 8.1 and a 5.3 tahoe , just all around awesome vehicles at the pinnacle of general motors before everything became over loaded with computer problems and active fuel management bs,,,,

[@mrgmc6314]

Wow that air flow was severely restricted ..

[@InnocentMiscreant]

The intake and heads on the 8.1 is not meant for high performance and they think the shelf would help air distributuon when really just makes it worse

[@vatechguy3]

When you cut the pipe out, why did you only weld a plug on one side and leave the other side open?

[@LawrenceTolman]

The other side has a block off plate on the outside of the manifold. No need to weld it shut

[@Bryan-FAA-certified]

LT, why didn't you just use the new Raylar intake? Instead of cutting on the old one 😮

[@LawrenceTolman]

Saving that for my “race” motor

[@jacobthornock317]

Color is pretty slick. Clean but not over the top. On the truck, those look like factory 18", but what tire size are you running. I have some for my 72 C-10, apart from swapping 70 6 bolt hubs and axels vs adapters, I am not sure to run a 50 or 55 series tire on them. 245-265 widths. Your thoughts?

[@autumnjeserich2689]

what welder settings did you use and what rod? I'm going to be attempting this today

[@davidjumara6558]

Why did you leave the rest of the pipe you cut out open

[@mandlebaum17]

It surprises me to see someone who claims to be a neat freak - constantly sweeping and vacuuming his home garage/shop - do things in his business shop like blowing aluminum chips and filings around with an air nozzle and spray painting out in the open near customer vehicles. You may say that those vehicles are far enough away that they wouldn't be affected and for a majority of the airborne debris you are right. But some of that stuff can and does fly farther than you think and it will inevitably, eventually land on and/or in customer vehicles. I think you would be very well served to get some dividing curtains to keep your personal fab area separated from customer pay bays

[@arthurrodesiler3109]

I think someone makes some special two part expoxy that is suppose to work good to.

[@414Chevy]

That looks like they made that reverse shelf thingy as a velocity chamber. If I'm right, it might cause it to feel doggy at low speed, from a stop. Might have turned your manifold from a long runner to a semi short runner. Nice work though, I can't weld to save my life.

[@dadgarage7966]

Yeah, it was likely a tuning element to improve torque and throttle response off idle and at low speeds.

[@b1g_ben-473]

Shows are awesome channel is awesome just need longer vids buddy either way I’m still a faithful fan always checkin to see when you upload .

[@ActionJackson2360]

Is that "unnecessary port" the pcv or egr port?

[@steve6992]

Just the tip when welding aluminum, try and avoid sanding discs or cutting wheels, it embeds trash into the aluminum and makes it difficult to weld

[@justfoundmy10mm]

What would you recommend to use?

[@anthonymason701]

​@@justfoundmy10mmin my experience, roughing it to size with a cut-off, shaping with the flap disc, then finishing off with a carbide burr on a die grinder works pretty well.

[@justfoundmy10mm]

@anthonymason701 that is what I figured. Thank you for the information.

[@raystevens687]

Hope your Idea 💡 will work. Here is something to consider what do you think about Edelbrock intake do you think it looks the same as a stock intake or do you think it might be different anyway I was thinking you might look into that before you even think about starting your engine. This is just an idea only hopefully you'll consider this.

[@manworksgarage]

Never seen an edelbrock intake for an 8.1

[@georgecerda7802]

I've had a similar experience but it turned out that my line was kinked and the argon was not flowing properly.

[@edgarparrish3457]

I need your opinion on this situation I want to swap out my Tbi 4.3 for a Tbi 5.3

[@kristoferpearson1537]

You can always braise it back together.

[@jakewade7388]

The ports on the intake look like cathedral. Does that era big block have cathedral port heads?

[@suelo_abuelo8066]

Why didn’t block off that other hole from the tube? 😳

[@shawncordeiroTerraceBC]

arc blow, why didnt you tack it then weld in the flat ? less of a challange i guess lol

[@CeeDubFX]

Are you going to install some headers? Maybe some short tube headers? Long tubes could give you more power?

[@LawrenceTolman]

Since this one is turbo’d it’s gonna keep its manifold based turbo setup, it a tubular header would likely help as well

[@t.l.robinson2162]

At the track the Ugly Truck is going to surprise a few people who do not know better than to judge a book by its cover.

[@danielbremner7805]

Does the other end of the "pipe" that you removed need to be sealed up, as well as the one you sealed up on the side already?

[@LawrenceTolman]

The other end of the tube goes up to the outside of the manifold where there is already a block off plate, so no need to weld that tube. Plus, if I wanted to integrate it into the PCV system that would be a great spot to pull dirty vapor out of the crank case.

[@damianellis3554]

They did it for sound deadening to make the motor or not loud sound

[@TheBeerBox80]

For the 8.1 you would have gotten another 75.6 Horsepower if you had painted the intake red.

[@LawrenceTolman]

Dang it! Missed opportunity there

[@invalidaccount2315]

@@LawrenceTolman a red stripe decal across the heads means moar faster 200% hp increase to the awd tourque blaster

[@craphittingthefan2360]

Hay LT are you not at power Nation anymore, I don't have cable anymore so I have no idea what's going on?

[@turboflush]

Looks to me oem was after equal distrobution and long runners.

[@mahdialsenussi3066]

Nice work ❤️ 👍

[@Silkmaster4200]

For porting etc. on intake manifold will it lose a lot torque? But gain hp instead? Probably a reason design it that way for build torque? Just saying.

[@LawrenceTolman]

According to the dyno chart on Raylar’s website, this mod will gain HP + Torque everywhere for what that’s worth

[@raystevens687]

Here is another idea 💡 look at the bottom of your Raylair. Intake manifold. Hope I didn't mess spelle the name of your new intake manifold

[@bradtodd3639]

What model of tig welder do you use?

[@swissroll71]

TolmanR Intake

[@PeterHatch-mx7zc]

You could do a build for PAUL at FaB Rats for his 4x4 tow truck ! We all out here in utube land would watch that !! How say us "utubers"

[@ralphjones7240]

Have you tried pre heating?