Gen 3 2.8L or not...

[sanjay]

As it turns out I like building frankenstien engines and when my 3400/3500 hybrid is done I'll have a ton of parts lying around. I'm looking at building another frankenstien engine but I don't know if any of this stuff will work together.

The idea is I want a short stroke high revving, high compression gen 3. At my disposal I have a 00+ 3400 top end. I have or will have soon a 00+ 3100 bottom end, a 3.1 bottom end and a 2.8 bottom end.

What combination of parts that i already have can I use to make a 2.8L Gen 3 engine with nothing higher than 11.5:1 CR??

Am I better off with just slapping the 3400 top end on the 2.8 gen 2 bottom end?? If this is anything like a 3X00 top end on a 3.1 and logically to me it should be then this combo will be 9.X:1 compression?? I'd prefer the gen 3 block but whatever gets it done reliably for the least money will win here.

The 2.8 bottom end interests me because performance cams are pretty inexpensive but if the full g3 2.8 can work I guess I could also do a regrind. If I do this it will be on an extreme tight budget so a WOT cam is not really an option (that's for my 3400/3500 motor)

So assuming that i either stick with a stock cam or something not too crazy what size tb should I be using?? I've got a nice little 62mm FDP here but if a stock 3X00 cam will be enough then so be it..

I'm thinking 7000 rpm should be the highest this thing revs. I'd do the lt1/ls1 lifter mod and i guess some ls6 valve springs.

I'm looking for something like 175 crank hp and he same for tq, if i can hit 200 well all the better but no more than that.

This will never get headers so gen 3 manifolds and 2.5" exhaust recycled form my other car.

In the end I guess if all else fails I can put the 3.1 pistons in the 3100 and have a high compression 3100 with a reground cam but the 2.8L displacement interests me so I'd like to continue.

As mentioned earlier this is only a a possibility. I'm just trying to figure out what is necessary and what I already have that I shouldn't sell or what i can trade for what i need.

Thanks..

Oh and I did search but I didn't find what I needed..

[Superdave]

3100 block, 2.8 crank, shotpeened rods and 2.8 pistons form a Camaro/S10 and the 3400 top end with a 3500 UIM.. high lift, long duration cam, 3500 "header" manifolds, 2" dumps into a 2.5" system.

That's all i can spit out right now.. i need another beer. :P

[LeftVentricle]

Stock cam is not where you wanna be. Power peaks at 4800.

[IsaacHayes]

Yeah, 3400 top end, 3100 block, with 2.8 crank and rods, with the camaro iron head 3.1L pistons would be high compression 2800 basically. That is assuming 3.1/2.8 pistons are the same then that would work. Not sure what the comp would be but it's over 11. I'd have to play with the comp calc.

Or do the 2.8 short block wiht 3400 top end and camaro pistons if you want to keep the flat tappet cam for a diff cam, but remember to check pushrod length.

Or if you really want to go all out on a short stroke, high comp, big bore motor....heheh
3400 block, 2.8 crank & rods, 3.4l iron camaro pistons, 3500 top end, hot cam... LOL that thing would breathe and rev like no tomorrow.


** not sure on the rod/piston combos with the 2.8 crank. I think the 2.8 crank and rods works with any of the other long stroke pistons, but I'm not sure. If not you could go with the 2.8 pistons but you'd loose the compression. Custom would work but costs lots of money.

Good thing about shorter stroke is it helps resist detonation with higher compression.

[Superdave]

2.8 and 3.1 pistons have a different pin height to make up for the stroke difference.

I built a few "2800" setups in desktop dyno based on what i posted before.. I based the head flow numbers on some from an unnamed source, and the 1393 cam from the store here. 243 crank HP @ 6K and 244 TQ @ 3500 RPM

It was still making 201 HP @ 7K and 115 HP @ 9K. It has a nice torque curve and hits about 96% VE around 5K RPM.

[ForcedFirebird]

Yep, Dav'es correct. The rods didn't change. The pistons have to match the crank, but was there any 2.8 crnks with the reluctor on them? Might have to use the external DIS wheel.

[IsaacHayes]

Ah, ok the pistons changed not the rods. I didn't think of the 2.8 IRON head rwd pistons. yeah that would do the compression. For got they had 2.8's.

FWD 2.8 had DIS. use the 2.8 FWD crank, 2.8 RWD iron head pistons.

All beretta's had DIS, and they had 2.8 FWD so yes, it has the reluctor. I think the gen1 2.8 FWD in the first cavy's had a dizzy though (and were iron head IIRC). The Gen2 FWD aluminum headed motor 2.8 FWDs will have it.


Dave: what does the simulation show with that same setup, only a 3400 with the 3.4L rwd pistons and 3500 top end instead? More stroke and bore with better heads hmmmm.

[sanjay]

3100 block, 2.8 crank, shotpeened rods and 2.8 pistons form a Camaro/S10 and the 3400 top end with a 3500 UIM.. high lift, long duration cam, 3500 "header" manifolds, 2" dumps into a 2.5" system.

That's all i can spit out right now.. i need another beer. :P

For now the 3500 UIM & Ex Manifolds are not an option. Maybe in the future but that stuff isn't exactly easy to come by here.

Damn it, I can't do multiple quotes??

So to give you an idea of where this came form well my van's transmission blew a few weeks ago and it's not worth fixing so I need to buy a car. As much as I want 4 X 4 I can't find one that I like and I don't have a choice but to get a car soon so I'm looking at and automatic '89 Z24. Yes yes, automatic..this is the little detail that makes all this an idea. I'm leaving the car stock for now but as soon as my other '89 Z24 is driveable the auto will get tossed for the more favorable 5 speed. I have all the parts here to pretty much do this for free so I was thinking, while the motor and tranny are out, why bother putting the gen 2 2.8 back in, espesially with all the other parts i have lying around here...

Ok as interesting as the short stroke 3400 sounds I want this to be as little displacement as possible. At least the 2.8 MPFI badges on the side of the car will still mean something..

So from the info collected so far the build will consist of this (Correct me if I'm wrong)
3100 Block
2.8L FWD Crank
2.8L Iron Head Pistons (Need To Buy)
60 Degree Rods (Shot Peened)
Fully Ported & Matched 3400 Top End
3400 Phenolic Spacers
Ported 3400 Ex Manifolds
LS1 Lifter Mod
LS6 Valvesprings
Possibly My Aluminum Flywheel (I think the other motor will be a little too abusive on it)
UDP
Still have to choose a cam grind. The 1393 grind looks amazing but I'm going to want a near stock idle. I also will need it to start with absolutely no issues in -104 degree F (Hope I did the conversion right - 40 degrees c). I want the power band to mimic that of a 2.8L VW VR6. As great as 243 crank HP sounds 200 will be more than enough for a car that will mostly be driven in snow and when the more powerful car is down. What would be really nice is a regrind of a stock cam that will NOT require me to use custom length pushrods or possibly let me use gen 2 pushrods. I also want to stay within a very safe lift range on the ls6 springs, let's say no more than .450 - .475" max lift (Need to buy or send out).
TB choice I guess will be directly related to the cam chosen. I can choose from a stock small port 3100 TB, Stock 3400 TB, FDP 62MM TB Or a 65mm Intrigue TB using the TCE Adaptor.

So will a stock timing chain be up to the task?? I'm not looking for perfection here and I don't mind if the chain stretches a little just as long as there are no piston to valve issues due to stretch or the chance of the chain snapping.

Looks like I'm gonna need a second engine stand. Damn winter is long...

Let me look at a gen 2 bottom end again for a sec. The benefits are 1) I don't have to bother with a custom front mount bracket 2) cams & timing chains are relatively inexpensive. The downside would be custom pushrods unless I retrofit the 3X00 heads to use guide plates and and adjustable rockers. I'm not 100% sure but I believe the deck height of the 3X00's and the gen 2's are the same so if I used a 3X00 top end on a gen 2 block with a 2.8L Fwd crank and some 2.8 rwd pistons wouldn't the net compression be the same as the above mentioned full gen 3 2.8 combo??

[Superdave]

the LS6 yellows are ok but you can't run more than .500 lift or so on them. Comp 26915's are good for almost .600 lift.

the spacers aren't needed so i'd save your money there. I'll be off work and bored tomorrow.. i'll plug in a few different cams to DD2K and see how the 2800 likes it.

the poor oiling of the Gen2 block should be enough to scrap that idea

-40c is -40F Use google, it's good for conversions. just enter: Convert -40c to -40f in the search bar.

[IsaacHayes]

Forget the ported 3400 manifolds, try to find some from a 3400 2005 Impala/etc (maybe 2004 had em too, not sure) as they are the same style with the crossover, but have much larger ports like 3500 manifold size. I'd skip the phenolic spacers for now and put that $ towards the other stuff.

Pushrods are not too costly. remember with a gen3 block in your old car you will need a front mount. Six Shooter isn't making them right now. you could use a 2.8/3.1 mpfi block though and do the hybrid with that and then use an off the shelf cam shaft. Pushrods I think are only $75 or so from pushrods.net

Yes net compression will be the same with gen2 block. It will be like 11.5:1 or more I think with camaro pistons and 3400 heads, but it has been done before on pump gas with a good tune (3400 with camaro 3.4 pistons). And since you'll have short stroke it will resist detonation even more.

With this you'll want a LX5 TB. With the cam and compression and gen3 heads a 65mm is perfect. I'm running one on a stock gen3 long block, with 3400 and 3500 intakes and it's great. Might as well put on the 3500 plenum then, it's not much work to do so at all really.

[sanjay]

the LS6 yellows are ok but you can't run more than .500 lift or so on them. Comp 26915's are good for almost .600 lift.

the spacers aren't needed so i'd save your money there. I'll be off work and bored tomorrow.. i'll plug in a few different cams to DD2K and see how the 2800 likes it.

the poor oiling of the Gen2 block should be enough to scrap that idea

-40c is -40F Use google, it's good for conversions. just enter: Convert -40c to -40f in the search bar.

Well considering the difference in price between the 26915's and the LS6 Yellows and the extra hardware needed Vs. the ease of installing the 26915's I'm gonna go with the Comp springs.

The spacers I already have on my current hybrid so I'll just re-use them.

3100 Block it is, the mount is not too much of an issue. I have one already for my summer car and I can just get it copied pretty easily or wait got SixShooter..Isn't he The Raven here??

I though the conversion was off. I have a built in unit converter in my nifty scientific calculator but it apparently doesn't work right.

Sounds like you guys want to see how far I can take this 2800 but after seeing Dave's cold weather startup video I'm going to be quite conservative in this build and leave the craziness for my other car.

I want to use as many part as I can that I currently have and the 3400 Ex Manis are also sitting on my hybrid so for now those will get used.

Ok newest list of parts. This time I'll list what I already have and what I'm willing to buy:
3100 Block (Already Have)
2.8L FWD Crank (Will have if I buy this car)
2.8L Iron Head Pistons (Need To Buy)
60 Degree Rods (Already have, need to get shot peened)
Fully Ported & Matched 3400 Top End (Alredy have, need to port)
3400 Phenolic Spacers (Aleady have)
Ported 3400 Ex Manifolds (Already have, need to port)
LS1 Lifter Mod (Need To Buy)
26915-12 Comp Springs (Need to buy)
Aluminum Flywheel (Already have, might use)
UDP (Already have)
Cam (Need To Buy, Let's see what Daves Sims come out with)
Pushrods (Will buy if nescessary)
65MM TB (Have the adaptor, need to find a dohc tb)

The 3500 UIM & Ex Manis or the larger port 3400 ex manis are possibly but highly unlikely option for the future but an un-required expense at the moment.

Please remember my goal is 175 to 200 crank hp. Obviously I'll take more if it just ends up being easier to do so but idle, drivebility, and cold weather starting are more important than all out power in this build. This car will probably see a lot of stop and go traffic when I go back to school.

I almost forgot the budget also extends to the clutch. I love my spec stage 3+ in my summer car so I'll be getting a spec again. I'm looking at a stage 1. I really don't want to spend any more than that so i don't want a motor that will make it slip when I get into it.

[IsaacHayes]

Ah, from what you have that looks to be pretty good. Cammed 2800 w/ high compression. It should do the HP goal you have set, considering a large port 3100 is 175hp. So you are loosing .3L but gaining a cam and compression. Should work out just how you want it. MPG should be very good with the small displacement, cam for more efficiency, and compression as well gives you efficiency and helps a lot with mileage. Nice build for a daily driver!!

[sanjay]

Ah, from what you have that looks to be pretty good. Cammed 2800 w/ high compression. It should do the HP goal you have set, considering a large port 3100 is 175hp. So you are loosing .3L but gaining a cam and compression. Should work out just how you want it. MPG should be very good with the small displacement, cam for more efficiency, and compression as well gives you efficiency and helps a lot with mileage. Nice build for a daily driver!!

And that's exactly what I want!!

Check Out what I found below..

http://cgi.ebay.com/ebaymotors/GM-GMC-CHEVY-S-10-2-8-173-PISTONS-PISTON-SET-224-2130_W0QQitemZ310003269938QQcmdZViewItemQQptZMotors_Car_Truck_Parts_Accessories?_trksid=p4506.m20.l1116

[IsaacHayes]

Hmm. Will they clear the 3400 valves and such with extra lift/duration? (just wondering I don't have a clue either way). Nice price if they will work!!

[Superdave]

Snag those quick! lol


I've seen a hybrid using 3.1 flattops and a H272 cam so i'd imagine it would be ok. Keep the cam duration resonable and you shouldn't have problems.

I could tune out my startup issues in the cold but since It's seen snow twice in 3 years it's really not needed. In the summer it fires right off and runs great.


for the timing chain, get a GM set for a 99 or older 3400.