/6 build

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gforcejunkie

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I am currently building a 71 duster with a 198 slant 6 and 3 on the tree. I am using the slant 6 as a learning project before i put the new engine in during the winter and just want to see what it can do and if it blows up oh well. What I have in mind so far is building a custom intake manifold running EFI from an 84 buick 3.8l. Installing a comp cams cam kit with the following specs:
P/N: K64-241-4

Cam Style Mechanical flat tappet
Basic Operating RPM Range 1,200-5,000
Intake Duration at 050 inch Lift 220
Exhaust Duration at 050 inch Lift 220
Duration at 050 inch Lift 220 int./220 exh.
Advertised Intake Duration 264
Advertised Exhaust Duration 264
Advertised Duration 264 int./264 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.440 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.440 in.
Valve Lift with Factory Rocker Arm Ratio 0.440 int./0.440 exh.
Lobe Separation (degrees) 110

I ordered an MSD 6AL-2 programmable and am going to be running an AEM data logger on the car to learn how different changes affect the car.
I am building a set of step-tubed race headers and am debating on tossing in a garrett GT3076 turbo with an air-air intercooler.

The next thing is should i put a 4 spd transmission in the car?

Does anyone think this is a good build? Any comments or suggestions would be greatly appreciated. Thanks. Also what kind of power would you expect from a build like this? I was thinking of running 8lbs of boost for a little while and then cranking it up slowly until she goes. I'm sure someone on here would be interested in how much boost a stock slant 6 can handle.
 
Do a quick search on this site that talks about installing efi on a slant 6 for common junkyard parts if i'm not mistaken
 
gforcejunkie said:
I am currently building a 71 duster with a 198 slant 6 and 3 on the tree. I am using the slant 6 as a learning project before i put the new engine in during the winter and just want to see what it can do and if it blows up oh well. What I have in mind so far is building a custom intake manifold running EFI from an 84 buick 3.8l. Installing a comp cams cam kit with the following specs:
P/N: K64-241-4

Cam Style Mechanical flat tappet
Basic Operating RPM Range 1,200-5,000
Intake Duration at 050 inch Lift 220
Exhaust Duration at 050 inch Lift 220
Duration at 050 inch Lift 220 int./220 exh.
Advertised Intake Duration 264
Advertised Exhaust Duration 264
Advertised Duration 264 int./264 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.440 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.440 in.
Valve Lift with Factory Rocker Arm Ratio 0.440 int./0.440 exh.
Lobe Separation (degrees) 110

I ordered an MSD 6AL-2 programmable and am going to be running an AEM data logger on the car to learn how different changes affect the car.
I am building a set of step-tubed race headers and am debating on tossing in a garrett GT3076 turbo with an air-air intercooler.

The next thing is should i put a 4 spd transmission in the car?

Does anyone think this is a good build? Any comments or suggestions would be greatly appreciated. Thanks. Also what kind of power would you expect from a build like this? I was thinking of running 8lbs of boost for a little while and then cranking it up slowly until she goes. I'm sure someone on here would be interested in how much boost a stock slant 6 can handle.
Click to expand...

What is your goal for this engine in terms of horsepower and what will your goal be in terms of elapsed time and mph for the Duster, once the engine is complete and in the car, running?

Please let us know what you are after with this project, because without a goal in mind, it's impossible to say whether what you have suggested is going to work for you or not.

Once we an idea of your desired finished product and its expected capabilities, it will be a lot easier to evaluate your progress, so far.

For example, is this going to be a low-budget exercise wherein you use a lot of used parts, and have a dollar figure for the engine in the $800-$1,000 range, or will it enjoy a $4,000 cap on parts and machine work?

Can you be happy with a Duster that will run 15-flat quarter miles, or would you rather spend the extra money that could produce 12-second timeslips?

You can build an engine with a 4-bbl carb (or, efi), that is normally-aspirated, with the cam you mentioned, headers, some 11:1 pistons, and big valves in a ported head without breaking the bank, but that engine will only run, probably mid-14-second e.t.'s at best.

But, it will be reasonably priced.

To run some 12 second times, (or quicker) you're probably gonna need some form of power-adder, like a super- or turbo-charger, or N20.

But, it can be done, and with normal, everyday parts that are not hard to find.

It's just more money, that's all..

But, how about letting us know your druthers; you have some good ideas and there are people here on FABO that will gladly help you achieve your goals, once we know what they are.

Just talk to us.... :D
 
Thanks Bill. I'm not putting any restrictions on the cost for this as i already have the majority of the parts that i listed. The only thing that i don't have is the custom intake the exhaust and the cam. I want to stay away from touching internals (other than a cam) as I am trying to figure out just how much power it can handle and use it as a learning experience. I would like to see this thing make at least 300hp. Does that sound possible running a turbo, cam, efi, intake and exhaust?
 
Sounds quite ambitious for an engine you plan on dumping later, especially the EFI part. Who knows, if you ever get there you may learn to love your slant. There are many straight sixes in past performance cars, like Datsun 280Z, BMW's, ...

Turbo is the ultimate in a slant, and much easier than with a V-8. You can find posts of a guy who runs 1/4 mile in the 10's with a turbo slant and few V-8's can do that, even high-end modern cars. Read Bill Dedman's posts (above) for much info. His build is beautiful, but I am guessing you are not retired like him, so life may get in the way.
 
I'll be watching this thread very closely. You have literally duplicated my parts for my future build. I do have oversize valves and plan on getting my head ported and polished.
 
gforcejunkie said:
Does anyone think this is a good build? .
Click to expand...

I don't.
Your parts are all wrong. That cam would probably work for a mild turbo build, but is way too mild for a NA slant. I wouldn't even use that cam for a turbo, unless I already had it on hand. If you need to buy a cam anyway, order the right cam for what you are doing. Step headers are only needed for a full tilt race motor, and certainly not for a turbo motor. For a NA motor, with a decent cam, you need compression, for a turbo, not as much.
Like Bill said, you need to determine what you want to do with the car/engine, then build to that goal.
As for the EFI, why the buick setup? It would probably be easier to get an aluminum intake manifold, weld in injector bungs, buy/make a fuel rail, and use a mega squirt or other after market ECU.
 
I forgot about the port and polishing, I will be doing that as well. I chose the buick setup because it was designed for a slightly larger engine and was also used on an engine with a turbo. It is quite easy to tune since it is a bash style efi system. I agree it would be easier to just buy an aluminum intake manifold and weld on injector bungs or purchase a clifford that already has the bungs and they just need to be tapped. I don't see the fun in doing something the easy way so why not build my own. I'm definitely thinking I will use the turbo. The compression on the stock slant six is nearly perfect for running a turbo. Obviously it is not the best for a naturally aspirated engine. Like I said the goal of the build is to learn as much as I can from it. I guess you could say while I have it running it will be used for pro-touring.
 
gforcejunkie said:
I forgot about the port and polishing, I will be doing that as well. I chose the buick setup because it was designed for a slightly larger engine and was also used on an engine with a turbo. It is quite easy to tune since it is a bash style efi system. I agree it would be easier to just buy an aluminum intake manifold and weld on injector bungs or purchase a clifford that already has the bungs and they just need to be tapped. I don't see the fun in doing something the easy way so why not build my own. I'm definitely thinking I will use the turbo. The compression on the stock slant six is nearly perfect for running a turbo. Obviously it is not the best for a naturally aspirated engine. Like I said the goal of the build is to learn as much as I can from it. I guess you could say while I have it running it will be used for pro-touring.
Click to expand...

Well, I am just an old codger who is easily intimidated by new technology, and avoids it whenever I can.

Having said that, I am going to go out on a limb and suggest that, as complicated as it is to get a well-working turbo setup is on a slant six, and considering that there is proof positive that you can, without resorting to heroic measures like a roller cam, exotic ignition and wild rpm, you could build a motor like the one you want, and simply use a blow-thru modified 4150 Holley 4bbl and forget all about adding to the considerable tuning issues (and, many more) of a dedicated, home-brew EFI system.

Both Tom Wolfe and Ryan Peterson manage to make about 500 HP with setups that rely on 1 4bbl carb, and what would be the advantage in switching from this to an EFI, unless you are well-versed in the nuts-and-bolts and tuning of such a system and it is easy for you.

I would RUN from the added complexity and "cut and try" problems that will undoubtedly arise, trying to get an EFI system to work well with a turbo application, but that's just the opinion of a guy who was well past his prime in the 1980s... older than dirt, and probably as dumb...

Three hundred horsepower was achieved by Tom Wolfe by running a stock slant 6 with one 4bbl added on, but he had to boost it to about 20 pounds to get that.

That is not a recipe for longivity, RE: piston life.

My guess is that stock, cast pistons won't live a very long life if asked to perform at much over 10 pounds of boost (15 with an alky injector.)

Ten pounds of boost won't get you 300 hp.

If you want an engine that will live under the boost conditions necessary to make 300 hp, I think you're gonna have to pony up for some forged pistons like the Wiseco ones in our car.

As a f'rinstance, I'd say that a 300 hp reliable turbocharged /6 would require maybe 16-17 pounds of boost, breathing thru a ported, big-valve head, using an alky injector and one 4bbl carb, that was maybe a 600cfm unit.

That is not a cheap engine (about $1,400 for the head, and $1,100 for pistons, rings and rods) but there's not much else to buy for it that's very expensive.

That engine would put a 3,000-pound car solidly in the mid 12's, and have excellent driveability, both on the highway and around town.

I think Charrlie's right, though... that cam you have is too mild for a normally-aspirated engine and has too much duration for a turbo /6. But, flat tappet cams are cheap for these motors. Listen to Charrlie; he's forgotten more about these engines than most of us will ever know...

We'll be watching your build with lots of interest and enthusiasm. Keep us posted!!!:blob:
 
The needs of a naturally aspirated engine and a pressurized one are different particularly in regards to pistons and valve timing. Charlie and Bill know whereof they speak.

The GM 3.8 EFI seems to be a good choice for the Slant Six. The link from SlantSix.Org below is fairly comprehensive and has pix for the shopping list.

http://www.slantsix.org/articles/dibiase_efi/efi-conversion.htm
 
Thanks Bill. I wasn't sure how much boost it would take to build a 300hp /6. I was trying to find some clear info on it. I will have to rethink my plan and get back to you guys on the new ideas.
 
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