CARBURETED HO 8.1L GEN 7 496 TEST. HOW TO RUN A CARB ON YOUR 8.1L EFI, GEN 7 BBC? WHAT IS IT WORTH?
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- čas přidán 8. 04. 2023
- CAN YOU RUN A CARBURETOR ON YOUR GEN 7 8.1L BIG BLOCK CHEVY? WHO MAKES A CARBURETED INTAKE FOR THE 8.1L? HOW MUCH POWER DOES A CARBURETOR MAKE? IS A CARBURETOR BETTER THAN EFI ON THE 8.1L? HOW MUCH POWER DOES A 425-HP HO 8.1L MAKE ON THE DYNO? CHECK OUT THIS VIDEO WHERE I FOLLOWED ALONG WHILE MY BUDDY ANDY MITCHEL AND STEVE BRULE RAN AN HO-VERSION OF THE 8.1L GEN 7 496. DESITINED FOR A 28-FOOT BOAT APPLICATION, THEY EQUIPPED THE MOTOR WITH A DART DUAL-PLANE INTAKE, EDELBROCK CARB AND MDS DISTRIBUTOR FOR A QUICK DYNO SET UP. HOW DID THE CARBED, HO-CAMMED 8.1L COMPRE TO MY STOCK AND ZZ502-CAMMED EFI 8.1L?
- Auta a dopravní prostředky
I’m a boat mechanic and many boats use these 496 engines. They are fantastic engines and easily push 18,000 pound boats. Diesel-like torque
Thank you Richard for the low RPM data. 😊
My pleasure!
Love seeing the mercruiser 496! I have two 8.1’s in my boats
How do you judge if you’re telling me on something that like that. It is it waves per gallon lol
@@jeremytalcott4161 Nautical miles? Lol
How big is the fuel tank?
@@Matp345 bet it’s not big enough lol
$1000+ in gas per day at lakeside/oceanside pumps with a big block, if you're actually running it up and down the lake. Of course, if you're just puttering around it's going to use less. There is a lakeside VP fuels gas station on Lake LBJ in Texas about an hour away from me, the high pot stuff is $7 per gallon. Even the 90 octane (lowest available) is about twice what pump midgrade is. At least it's all ethanol free.
Like Brule said, gaseous fuel (propane, nat gas, waste gas) is a different animal. That manifold may not be made for gasoline. That'd explain the distribution/misfiring issues.
I wonder if the generator that these are in is a 1,800 or a 3,600rpm unit? My Onans run at 1,800rpm. 4-pole gen end. A much more mellow sound than a 3,600rpm unit. But also half the horsepower. My air cooled twin-cylinder 1.0L Onan only makes a whopping 13HP. It'll run like that forever just as long as I keep an eye on the oil.
This is a great starting point for testing. I think the misfiring may have contributed, some not all, to the poor low RPM performance results. Also, with these guys running this versus your more comprehensive testing. It left some intresting questions in mind. Obviously, GM originally designed this engine with a lower to low-midrange power band in mind. With that being said, it has already been proven that this engine can be a strong performer at the high end as well. After you do more comprehensive side by side testing with carburetor vs fuel injection. It would be interesting to see a carburetor vs Sniper TBI test as well. Great stuff Richard! I am looking forward to more testing on this engine platform.
I for one can't wait to see more testing on a carbed 8.1.
Richard, you have the best engine dyno video s on CZcams, Thanks
Thanks, great information to have.
Thank you so much for these 8.1 tests!
Geez, that carb'd intake flattens & stretches the torque curve out nicely, it's the manual trans intake!
So interesting !
I just got one of these guys in my shop, never seen one before. Came out of a 28ft Checkmate. Yep they look like a big ole LS. Apparently they`re stroked 454`s...4.375 stroke x 4.25 bore. Looks like there`s potential in the heads. I think the pan is wider, its certainly deeper and its a box cast aluminum pan. I believe if the heads were ported, more compression and more cam 650HP+ is in reach on pump gas.
Very cool video... I've been considering a cam & intake swap in my 8.1 powered boat... (I already have a Dart 4150 intake) but thinking bigger... since I also have a couple 8.8 PSI (Power Solutions Intl) 535cube engines which are basically the 8.1 on steroids. 4.350bore x 4.500 stroke... Forged steel cranks, forged 10:1pistons (in LP version) better rods and much better heads and intakes. Heads use flatter valve angles and LS7 1.8 ratio rockers and beehive springs on all 16 valves. I have a few 496HO cams to try in them.
Very neat engines with a ton more potential than the 8.1. Would love to collaborate with R.H. to get one of these on the dyno... but Im on the opposite side of the US in GA. Not sure how to make that happen. Would make for some really good dyno time.
Quite a difference in midrange power but nearly identical peak. Can’t wait to see if your carb numbers follow the same curve. Interesting that Mercury rates this engine for Wide Open Throttle at 4700-5000 RPM, which is below the power peak. Anyone wanting to get the best top speed will definitely want to prop it to the higher end of, or over the recommended peak. The marine style exhaust manifolds vs headers might lower that peak too though, so who knows.
Love the shorter videos too.
Glad you like them!
I'd sure like to see Edelbrock make a Performer RPM Air Gap for the 8.1. Except that peak RPM on a stock short block should probably kept below 5800.
Carb intake vs EFI comes down to application, 8n my h7mble opinion. For my custom crawler build, I'm thinking keeping EFi and ZZ502 cam based on your video.
I have a supercharged lq9 in my escalade, and I would love a turbo 8.1!!!
Interesting video. Lots learned. Might have to change my build a bit. I took gen V 454 bored out to 496 and am currently building a stroker of it for my boat. Edelbrock, performer rpm airgap manifold, 1 inch spacer, quick fuel, M-850 carb, Elgin industries E1143p hydraulic roller cam - .576 lift 246 duration 108 degrees of lobe separation and finally AFR enforcer 335cc heads. Power band should be from 2000-6000rpm. Hoping for 650hp and 600ft/lbs
Your combo should be much stronger. I wouldn't change a thing.
492 at 1800! Holy smokes.
Remember the Stage 1 Buick 455s?
@@daytradescottie7253
510 ftlb.....
@@daytradescottie7253No I think I missed that 1 actually.
they didn't do 492 lb-ft at 1800
@@richardholdener1727
Nope.
Factory rated 510 at 2800.
I'd like to see one built to factory specs and see you tune it on the dyno. To see the true numbers.
Thats a crazy looking intake...long runners.
It would be cool to see the zZ502 cam vs this HO cam with the factory efi manifold, see if the firing order helps any power or torque
The firing order doesn’t change much.
@@hondatech5000 it changes intake manifold distribution, when two cylinders fire in sequence it draws from the adjacent runners
@@xozindustries7451 I understand. It changes what cylinders rob air from others. The thing is when you 4-7 swap you just trade what cylinders your robbing from. It will help if the manifold is being modified with that in mind and that the firing order swap now suits those mods. Without something trick in the intake it’s worth very very little if anything at all
With 8.1 irrigation engines I've swapped from stock intakes to Darts (on natural gas) and have seen zero performance differences....at a whopping 2,350 steady load rpm.
Modifying the intake might be worthwhile.
How do you measure "performance" on an irrigation pump??
@@jeffrykopis5468 vacuum (load). The more vacuum you pull loaded, the more hp you have.
The daily post of people looking for dart intakes should slow down 🤣
Not sure why these guys were having misfire issues, I have a dart intake with a bp202 cam and an 850 cfm carb in my c10 and I don’t have any of the issues these guys are experiencing here.
@Steve Kay I'm betting when Richard test it himself he will get it figured out .
I don't see the carb intake making the brute torque the factory intake does
Carbureted Very Good 💪💪💪🏆🏁👍
Richard, when you convert the late model LS and Gen 7 stuff to carb, how do you set the wide-open ignition timing curve? Is it similar to a conventional carburetor/distributor engine? Roughly 20 degrees at 2,000, 30 degrees at 3,000, topping out at 32-34 max?
Not sure why you guys were having misfire issues down low. I have the Dart intake on an 8.1 (with a bp202 cam) in my c10 and it runs fantastic. I also have a 1” carb spacer, but my motor runs fantastic in my truck
Could u helpnme with some pointers on my swap
Not sure why you don't run every mild engine down to 1800. Which is a very normal cruising rpm and it will tell people a lot of crucial info.
In the past when running 5.3 truck cams you start at like 2500-3000. I personally want to know how it makes power at the rpm I'm going to be spending 90% of the time which is less than 2500
Yeah if you start at 2500-3000, that really assumes a converter stall in that range also in order to make power when you give it the beans. Giving it the beans off idle with a stock converter and assuming the power is going to be there, is going to lead to disappointment.
please see the power curve started at 1800 rpm
@@richardholdener1727 Please read my entire post. If you had the time to write something snarky you could have at least read the whole thing. No kidding you posted at 1800 THIS TIME! My question was about all the other times.
@@ttank1994 Richard has said in the past they have a hard time getting the superflow dyno they use to load in smooth at low rpms. That dyno is really a racing dyno designed to be able to go to 10k. A dyno like mine made to pull smooth at 1k rpm is much larger diameter but then it can only go to 5k rpm because of inertia. My dyno would likely explode long before it spun to 10k. I have to use a speed reduction gearbox to run a high rpm motor.
@@bcbloc02 I've heard him say that too. More specifically he has said they have trouble with the Dyno holding the engine back at that low of rpm. In this case it was capable of holding back nearly 500 ft/lbs at 1800 so the explanation wasn't holding up. I'm likely missing something, but with rich's snark maybe not.
Hey Rich great video like usual. I reached out a while back and was trying to just get into communication with you about my 8.1 that I'm rebuilding and doing at the moment, obviously I'm not going carbureted ever going to stick with Factory fuel injection regardless of fuel supply in injectors but I'm just really interested because you are an absolute Master at this and I'm looking for your opinion between raylar which is one of the few out there available for this which I have one of their cams right now or different companies or what I can do to make the most power for a decent price and putting it together properly so it runs and breathes and work the best it can
have not tried Raylar
Thank you for replying. If you take a couple minutes and just look up rail or engineering. You'll see quickly or even on CZcams videos there's a lot out there they pretty much have their hands around the 8.1 and from what I was told back in the day from the partner Ray because it was Ray and Larry Ray isn't there anymore its just Larry now but supposedly they help GM design it back in 99 before it came out
Nice video Richard.
The LSA on the camshaft is a big deal.
The big block already loves camshaft, and a tighter LSA tends to make them make power down low and fall off rapidly up top.
So, for example, even on a 454, a 218/218/110 is done at 5500. So with the extra 3/8" stroke especially, a tight LSA is going to make power low, and fall off quickly on top. That ZZ502 cam is tight on LSA as well, compared to the cam in this marine engine.
Try the modified intake and big throttle body with a 234/242/112 in at 110° ICL, or even a 238/246/114 in at 110° ICL. That should carry the power out further, it will be interesting to see what it does to torque down low. The lobe design on the GM is mild, it's a soft Crane grind. If you get into the Extreme lobes from Comp (Billy Godbold designs) or the Voodoo lobes from Lunati (designed by the late, great Harold Brookshire) you'll probably find more power over all. However, if you use a tight LSA and the attending early ICL, you're likely to run into piston to valve clearance issues. That's another reason I suggest a wider LSA, and then a slightly later ICL. It's going to alleviate some of the piston to valve clearance problem, and at least extend the power band, if not move it up. 500-750 RPM.
Looking forward to more video.
WILL A 238 WITH A 114 EVEN FIT STOCK P-V?
@@richardholdener1727 the 8.8 heads from PSI will take alot of camshaft due to the changed valve angles. I have a TON of PTV clearance using a Merc HO cam on flat tops with NO valve relief at all. Would love to get this 8.8 I have on your dyno.
8.1 suburban owner funniest thing to drive everything is faster in stock form still a monster imma put intake,headers with 6psi turbo maybe 4-5psi she should live forever and that should put a stop to that 2nd place ❤❤
Kinda like a behind the scenes “engine masters” with Steve B at the dyno throttle of a problematic big block Chevy…
Well, "IF" I decide to build a project with a futuristic fuel-injected DYNOSAUR big-block I'm gonna have to go Avalanche huntin' for it then...I wonder what can I get out of it as a full-tilt boogie n/a street-strip combo???? & Will it be worth it or just build a LSX block for approximately the same amount???? ...p.s: I NEED THAT "DYNOSAUR" T-SHIRT IN ALL COLORS TOO, MONSIEUR MR. RICHARD🕺🏾😉🤩💪🏾
I have an 8.1 in a jet boat and love it. My cruising speed is around 30 at 3000 rpm. What people’s thoughts on prolonged use at higher rpm’s. Wot on mine is 4000 rpm at around 50 mph. In a 22ft river boat. How much is too much for too long. When I was a kid running old 2 ton trucks with big blocks it was no more than 3500 for more than a minute or two.
4000 RPM IS NOT HIGH RPM-IT WILL RUN LIKE THAT FOR A VERY LONG TIME IF THE TUNE IS CORRECT
Good place to source this engine is out of U-Haul Trucks 2005-2008 GMC 5500.
Andy hey man glad to see you around still.
If I understand it correctly, long runner EFI is decidedly better at everything under 5k rpm. That would be the way to go for boats and truck etc. Has anybody fabbed up a tunnel ram design with dual quads or two throttle bodies? Seems like a guy could take a couple of intake flanges and...
Could make a template of the ports which are cathedral shaped and make a sheet metal intake.
More 8.1L testing please!
You need to put the dart intake on the zz502 cammed 8.1L, or Raylar's bp I think it will make more peak horsepower than the stock intake. That "designed for generators" stuff is wrong.
You know this is an inverted and folded tunnel ram. Wished for grins, Richard, could you adapt a carb to the intake and see just how bad fuel distribution could be?
What about valve to piston clearance,you can't run much cam with stock pistons. Any idea what pistons to use to replace stock ones
It needs a tunnel ram😁
Are you planning on doing more videos for the carb 8.1 ?
yes
I'm currently working on the 8.8 liter version of this engine which came off a power generator.im stroking it to a 605 cid with a conventional BBC head.😊😊
they are cool
@@richardholdener1727 only had to relocate two bolts on each side and you got 1020deck block let you know how it turns out
It would be interesting to see the fuel flow in gallons per hour or per minute on these engines at maximum output, do you have any of these numbers available?
only on carb motors
Thanks fer translating to English(:
Hey buddy, what’s a good size carb to put on the 496 and the second question is is the roller lifters retained in this build.
depends on power output, but a 650/750 for stock/mild combos, then bigger as needed for higher hp
:Edit: The stationary generator would run at 1800 rpm to get 60 hrz.
Yes. I think dart tried to throw one together and didn’t really care about performance on them.
Could also be 1,800rpm. 4-pole gen end. That's what my Onans run at. So much easier on the ears.
No, they don't run any stationary engine at 3,600, 1,800 yes.
Andrew Wietzel you’re are correct they used 1800 rpm on generators but the dart intake was common on wells and they run higher.
@@amospgarcia9152we run irrigation wells at 2,150 to 2,350.
Awesome 👍👍
224 cam in 496 could hardly be considered a performance cam. Great for trucks etc., but I wouldn't think you were getting serious until 260 degrees or so on a 496.
I didn't know Dart made an 8.1 carb manifold. I thought only Raylar did.
Does this get rid of the need for the camshaft position sensor above the crankshaft pulley?
we run batch fire
I want to 8.1 swap my 02 Silverado 1500
Do you happen tp know if Dart will continue making these intakes? I'm needing 2 of them and they are nowhere to be bought
NO IDEA
Did GM run the same camshaft in the 8.1L whether it was in a Pickup vs RV vs Top Kick?
Yes, on road 8.1's were all the same internally besides oil pans and valve/seat material for propane/natural gas.
Hey rich do u know the deck height for this gen motor with a carb swap and wound it fit under a stock tri five chevy hood
These 8.1's and 8.8's are tall deck 10.2's.
Whats this individual coil AND distributor wizardry? Does the 8.1 have a place and gear for a distributor, they just block it off from the factory?
YOU CAN RUN A DIST WITH A CARB INTAKE
Yes but, i guess theres a gear to turn the distributor? I didnt realize that factory camshafts still came with distributor gears on engines that are factory distributorless. Mom, hes yelling at me.@@richardholdener1727
That's high performance. O' the block n the plugs. That's y. Think.
That motors is perfect for a 1966 Chevelle. Nasty, nice and nasty,
That's the way we like it.
Uh huh Uh huh- Smokey toasty
What oil pump are they running on that marine 8.1L? its making almost 90psi
I'll ask Andy
I heard that the firing order is different from the gen6 454 an gen 7 496 is that true
yes
Can you run a msd like 6014 ls to the 8.1 coils?
yes
I’m curious on the modified factory intake if you ran it with a stock throttle body instead of the 102mm how bad would it hurt the numbers? Basically if you did the intake baffle and floor mods but kept the 78mm or whatever it has how would it compare?
THE THROTTLE BODY MAY HAVE BEEN JUST A 92
That engine in a generator application would run 1800 RPM for a 60HZ output frequency.
or 3600
How much cam can you get away with in those?
Those cams sound very mild.
p-v limits cam size
@@richardholdener1727 yeah, i was curious if there was a general rule of thumb with stock ones of these.
I personally would rather just drop some earlier gen heads on this thing (assuming they are compatible) and that opens up a whole world of aftermarket intakes.
it takes a lot of work
@@richardholdener1727 Pretty sure it is a tall deck as well because they sell an extension for the distributor
Gen7 blocks are not compatible with older heads. They have 4 extra head bolts and are designed for the gen7 symmetrical port heads. There really needs to be better aftermarket support for the 8.1 and 8.8 platforms.
You have a celebrity there running your dyno at 6:00 in
Troy is awesome
@@richardholdener1727 I was talking about Steve. But I think you already know that
Can u use this set up for a caro or truck
yes
I'm looking for the passenger side fuel rail for 2005 496. Do you have one or know where I can find one ??
I only have the stock one
Can I get Andy's contact info?
Can it be configured to to run carb and coil pack?
Yes the same msd controllers that run standalone coils on an LS in a carb application will work for this
Msd 6014 runs the 8.1 fine.
Where is the oil fill 🤔
2.7 turbo 4 in the Silverado and New Colorado make as much hp and tq as the
8.1. Hp and tq curve almost the same . 310hp
430tq. Like to see one of
Engines on the dyno.
310 / 430 I'd far away from what the 8.1 did with the 502 cam and modded intake
@@randysullivan5723 stock
@@randysullivan5723But the ratings on the 2.7 are with all the accessories, full exhaust, etc. I figure a tune only on that 2.7 will bring it to 375hp and 500tq give or take. Still not going to have the instant response of a big block but just cruising around it’ll get a hell of a lot better mpg.
Won't last like a big block.
the dual plane is never going to match the plenum ram
🥝✔️Two plane 4bbl intake on a Cathedral port 496...Where did all the mid range torque go?
Taking the MIC out of the Mickey Mouse Electronics. Military Industrial Complex level 🎚️ parts be gone. No peanut, no oval ports...but Cathedral intakes. And now, Carb and MSD HEi! Like Steve B said, that's an intake distribution misfire.
Wow, that carbed intake is a let down honestly. It shows to go that despite its flaws the OE intake isn't terrible for what it is.
Wrong manifold should have used a Edelbrock performer rpm manifold would have got a better power and tq
When you find one for the gen 7, let us know....
Looks like everyone swapping to carb are missing out
How do I put a carb on my 8.1?
dart intake
Ok how do I do the firing order
496 will run all day on the water ford 460 you touch 4000 rpm’s one time on water and your done.
Those graphs with the same color get confusing .
I've run a lot of 8.1 liter motors and the LS series has them beat. You'd have to really do some stuff to the 8.1 to make them do any better than a cam swapped LS.
A couple of things to note though the 8.1 was made for trucks its definitely not designed to be a high performance motor, give it the heads cam intake treatment and your probably making over 700HP. 496 cubic inches is a lot of displacement it's practically begging for a giant cam and good head flow, and yeah a cammed LS will make more top end but comes no where close too the same low end power which is what a truck needs
Cam swapped 8.1 won't beat cam swapped 6.0?
Takes a lot of stuff to make it equal to or surpass a cam swapped LS. That was what I stated. Of course you spend a ton of money and it’ll make better power but if you’re on a budget forget about the 8.1.
@@chadsmith8779 if you only look at the hp curve .
Torque makes things move
NO LS WILL MAKE 492 LB-FT AT 1800 RPM
Had to turn the bass off. Rumble rumble rumble.
IT'S ALL ABOUT THAT BASS
Horrible looking Dual Plane, needs the big block carby twist to shorten those two long runners. 750 carb is small considering the cam and engine size.
Agreed. Should be 850-950cfm on there.
U-Haul trucks
I just think the dual plane is garbage 🤷♂️
Personally I blame squirrels.................
i need that 8.1 for my 03 yukon awd twin turbo i want to build
To me it sounded like a turd 😆& I'm a chevy guy 😜about 6200 pull would have just sounded better! wonder why they cant make head with 4 valve overhead cam ? Maybe they do & I don't know it ? Good show 👍
A test nobody wanted to see.
🤣💯💯💯
YOU SPELLED COMMENT WRONG
Oh, I'm glad to see this one. Now we know a hand built intake is in order.
HO’s came with a better crank. Kinda dumb looking at low torque for a boat motor. Most run 3000 and up, that’s where they live, any boat motor..
Mine spends most of its time at idle... or 3000-4600. From idle to 3000 is only used to dig out of the hole in the water. lol