Lightweight motor

[Wragie]

I know most guys don't pay much attention to engine weight but I'm hoping someone can help me out here. I'm new to the 660 so I won't have some specifics but here goes.

I was given a 91 2.8 (LL2-R) with a T5 out of a S-10. Complete was running and fairly low miles so just about perfect for my purpose. (The owner found out that staring fluid and fuel injection don't mix well.) That is putting it into a Locost or Stalker frame. That usually ends up about 1400 lbs by the time the dust settles. So to get more out of that I need to go with more power or lighter. If I can make the engine lighter it has plenty of power (for now)

I've been offered a Buick 3.1 don't know yet if it is G2 or 3. I've looked over the forums and from what I've found so far it looks like I have a few options. I do not have to be concerned about smog stuff and have a couple of megasquirts sitting on the self. So I'm inclined to use the HEI off of the 2.8 and the MS. I'm not too worried about intakes or exhausts at this point. I see there are some issues about the intakes matching up but I was planning on a mpfi controlled by the megasquirt using a custom manifold. Exhaust would be custom headers.

So I see two ways to use the 3.1. One is to hit it with a hammer until it runs in rwd configuration. I know about the starter and motor mount (not 100% sure about that one yet but looking still). I gather there a few things like making room for the hei to fit past manifolds? I assume it has the drive gear for it regardless. Or I could use the mega squirt and spark to do efi and ignition. Have I missed anything basic on that? One thing I haven't seen is if the 3.1 crank has the same flywheel bolt pattern as the rwd 2.8. I am assuming this is a manual/trans axle 3.1 not an auto box. But if it is an auto does it still work? I've been looking for a list of what I need from the car/engine but haven't seen a noob level list to know what to grab yet. This is sort of s sawp deal where he gets the bits I don't use on my or his engine (its a shop class engine)

Second option is to do the head swap. This seems a lot more straight forward to me. The only problem is the compression. Not being that familiar I wonder if there is enough meat in the head to open up the chamber enough to drop the compression down to where pump gas will work say 9.5-10.5 -1 Thick head gaskets? Used to do double gaskets on a few engines but have no idea if the gaskets design or the engine would let that work. It would be nice to do the heads without resorting to a rebuild to swap pistons.

So what other options do I have to get a lighter engine. And no I'm not going to buy the bow tie alum block (I'll wait for Santa) so I need to look at choosing the lightest combination of more or less stock parts. I would of course like to use that 3.1 as its free but am open to other options. If I can get 180-200hp with say efi, a cam and headers (mild mods) I'm more than happy. If I can drop the engine weight 50-60 lbs then it gets really interesting. Appreciate any and all info I can get.

Tnx!

Dave

[IsaacHayes]

1400 lbs!!! wow thats light!!!

You could go with a 3400 or a 3500 (185hp, 200hp). Modded would be even higher. That would haul!!

Anyway, if the buick engine is a gen2 or gen3, you'll need to go to DIS and fuel injection. MegaS can run it just fine this way. The ironhead intakes will not bolt up to the aluminum heads at all, and a distributor will not clear the intakes.

MS for spark and fuel is the way to go, or use an OBDI setup. There are plenty of tunes for OBDI out there, and several users running the gen3 on MS. You can even mod the MS 1 really easily to let it control spark without having to buy the MS 2.

Bellhousing/flywheel/flexplate bolt pattern is the same, but for a flywheel you'll need a 3.1/2.8 FWD one, as I believe the 2.8 RWD (depending on year I think) were external balance, and the FWD is neutral balance. Some RWD guys will have to chime in to see if that year 2.8 flywheel can be used or not.

Head swap will run into the same problems with using a dizzy/etc. For that don't mess with the heads (they don't leave extra meat on the castings, and you don't want to go into the quench areas), but you could swap FWD 2.8 pistons then the compression would be back down. You could swap the FWD crank and rods and pistons to stroke it to 3.1. Also you may have to drill a hole in the RWD block to put in the crank sensor or use an external one so that you can run DIS, as I'm not sure that year RWD block has a spot for a crank sensor since they were all dizzy, but you won't be running one with the aluminum head top end... Also you'll have to keep the flat tappet cam instead of roller hydrualic, and you'll need custom pushrods.

If you ask me it's easier to swap the whole FWD motor so you get all the benefits and deal with the starter issue. That way there is less problems.

If that 3.1 is a 3100 that's 160hp or so. If it's a 2000+ model, 175hp. Using a Gen3 motor is the most bang for the buck, and lighter than the iron head beasts.

Like I said at the start, a stock 3500 (LX9) is 200hp out of the box. With headers and good exhaust you'll be at 215-200 probably. A good tune is a must of course for any engine you swap. There are lots of people running the 3500 on OBD1, and Barry is running his on MS. Throw in a cam and your HP goes up even higher. I'm not sure if you've seen SuperDave's car, but its a 2nd gen cavalier, with a 3500 with headers, cam, port&polish, 75mm TB, and he put down 270 something HP to the wheels!!! He runs low 13's and is over 300 crank HP.

I say go Gen3, with your headers and cam and you'll have one fast beast!!!!!

[ForcedFirebird]

Since you are making your own motor mounts, I say just put the 3100 in as it is with some bolt-ons and cam. You will be pleased since most of you guys are happy with the iron head and carb, you will fly in your Stalker.

[Wragie]

Thanks for the responses.

It does sound like the best way to proceed is to just use the entire 3.1. The one question I still have about that is the engine mounts. I know one side is the same but the other side is different somehow? The standard boss is not drilled and instead uses different mount holes. Is that correct? And does anyone have a picture of what it looks like etc?

I stumbled across some pictures of the 3.1 head and I see what they meant about the heart shaped chamber. The first thing that came to mind is if a pocket or relief was machined out of the head to he bore size it would only have to be about 100 thou deep in order to make the chamber big enough to drop the cr down to a more livable level. Does anyone know how much material is there to play with? And does anyone want to try this out and let me know how it works out?

Cheers

Dave

[geoffinbc]

You don't want to change the combustion chamber. If you cut into it to reduce compression then you are going to move the quench pads so high into the cylinder head they wont be effective and that will kill your power.

IF your 3.1L is a 3100 then it is worth it to work with it and move the starter and make mounts. If it is just a 3.1L then I would use the 2.8L block and make it a 3.1L by using the components from your 3.1L then at least the starter and mounts will be a little easier to work with. Are you rebuilding the motor you are going to use?

A RWD transmission will bot to either and so will the flywheel and clutch.

An Iron head motor weights in around 400lbs take about 50 lbs off if your using aluminum heads.

[Wragie]

Was just thinking of using a rotary table and a mill to cut the heads. Not that big a job to do. Then blending the results. Bigger pain in the butt to do.
Would have been interesting to try. May not have been as good as the original but still would have worked. Probably would have screwed the emission's more than killed the power. Have done this before a few years ago.

I'm 99.9% sure about just grabbing the 3.1/3100. Should be interesting as it is the front end clip off of the Buick welded onto the front end on a Hyundai (Chundai?) and no he has yet to explain that one.

Better - Tnx fyi just over the hill in Kelowna.

Forced- had to go bbq dindin, will try later.

Thanks

Dave

[geoffinbc]

If you remove the quench pad you will ruin what GM calls its "Fast Burn" head. When the piston reached TDC the fuel and air sitting in the quench area (the flat parts of the combustion chamber) gets squished out over into the heart shaped chamber. This action creates a lot of turbulence and further mixes the air and fuel and making better, more efficient power. The fact that all the air and fuel is now concentrated in a smaller area means the flame has less distance to travel and so it burns up quicker. Thats is where the "Fast Burn" name comes from. The large flat spots also help remove heat from the chamber to help reduce detonation.

If you cut into the quench pads you essentially create an open chamber and now your back iron head technology.

You really have no reason to cut into the heads because with the piston choices and head gasket options you can create a lot of compression ratios. But the 3100 is pretty optimal for the street with a street mannered camshaft.

[Wragie]

I know that the cut isn't a nice way to do it. As you say has some unwanted results. It would blend into a shape that would be close to the pent something chamber. Trying to remember who did that one. Bit surprised no one had tried it before though. In a way I'm not as concerned with the efficiency as I am with the weight. The heads would still flow better than the iron heads and be lighter as well as being able to tweak the compression to a tolerable level.

Pretty sure I will end up just grabbing the 3100 and make it work.

Dave

[geoffinbc]

Well if you do get your hands on the 3100 then you wont have any compression worries. For weight, power and dollar ratio the 3100 and 3400 motors are the best

[Wragie]

Leaving the heads behind.

Does anyone know what the weight is of the intakes setup as well as the exhaust manifold? The intake looks like a rather heavy casting.

I won't need anything other than an alternator so any brackets etc will be long gone.That all adds up weight wise. Would be nice if I could get the engine installed and running under 300lbs.

Dave

[Superdave]

under 300lbs shouldn't be too bad. the blocks are around 80, crank is around 35 lbs. Agreed with the rest, the aluminum top end of the gen3 engines and the power output would be ideal.

you can put down about 200 to the wheels with a bone stock 3400, good exhaust/intake and tuning. With a good cam and headers 250 would be easy. I put down 275 WHP (316 crank) with a 3500, cam, headers and port work.


275 is fun at 2700 lbs.. i can't imagine what it would do at 1400 lbs.. lol

[geoffinbc]

Sorry but the block with caps weighs 101lbs according to the GM Power Manual. The RWD block is 5 lbs heavier. The 3X00 block are probably a bit more since the caps are more substantial and the block has more reinforcement.

[Wragie]

Any guess on what a very bare gen3 long block will weigh in at? Sans manifolds and any mount hardware etc.

Dave

[ForcedFirebird]

I weighed a 3500 minus the accy's, dry but dressed (including cast manifolds) and it was 340lbs. I would imagine the 3500 is a little heavier than the 3100 due to the crank weighing more...

http://60degreev6.com/forum/f98/official-lx9-weigh-in-t41003

[geoffinbc]

Any guess on what a very bare gen3 long block will weigh in at? Sans manifolds and any mount hardware etc.

Dave

Maybe 110 to 115 with main caps. But thats just a guess.