3.4l rwd in a fwd car

[donk_316]

Buddy, Instead of just saying "From the one I worked on I do not think a RWD block world work." Tell us why. What problems did you see?

[sharkey]

yes we are talking j bodies. my car is an 86 z24, it has an ironhead 2.8 with distributor. its the same engine bay as any 82-94 j body.

ok guys, since this doesnt look like it will work, id like to find out about some of my other options. keep in mind im not doing just a motor swap, im looking at building a motor up, just looking for a base

what about the lumina apv 3.1l ironhead/tbi motor. i read something about an mpfi intake not working because of webbing in the lifter valley. is this something i could mod to work, or is this motor completly out of the question???

fiero 2.8l ho: now im getting confused here, is the fiero a fwd or rwd block design??? will it bolt into a j body??? will i be able to use a 3.1l crank and 3.1l ironhead pistons to have a "stroker" motor???

i would like to get a bit more displacment when i build this motor. i find the 2.8l seriously less torque when compared to a 3.1l. granted the 2.8l reves a bit higher, but i find that the heads dont flow enough to keep it pulling.

[geoffinbc]

Ok On a J-Body there is a prop shaft support on the passenger side and a mount to the chassis. It supports the long extension shaft that goes from the tranny to the prop shaft on the right wheel. It uses the 4 bolt bosses on the side of the block which the RWD block lacks.

See the picture It is the aluminum block and will show you the comparison of the mounts. The Aluminum block supports all mounting positions but on a RWD block you will be missing the front 2 of the bosses labled "FWD bosses" so I do not know how you are going to make a RWD block work if you are missing the holes in these locations. Furthermore the mounts on the other side (which I do not have a picture for) differ as well is memory serves me correctally.

[sharkey]

ok, so unless i was to make custom motor mounts, it wouldnt work. if i had to do all that, i just go with a 3400 bottom end.

ok so back to my other post, what about the lumina 3.1l, or the fiero 2.8l, and fiero 2.8l with 3.1 crank rods and pistons??? (see my last post).

[geoffinbc]

Well a lumina 3.1L and a Fiero 2.8L with a 3.1L crank will be identical as far as engine design goes. If your comparing Gen I to Gen I

For the money though you cannot beat a 3400... You get bigger displacement, priority main feed oil system, intergral oil pan, high volume oil pump, roller valvetrain, and 4 bolt (well 2 vertical and 2 horizontal) center main caps.

Now your concern was that your ECM will not be able to run a 3400 correct? Well if you were to run 3.4L (or even 3.1L) injectors you should not have a problem supporting a full 3400 engine. Granted some minor tuning would be involved. However you distributor may be a concern I am not sure if it can be made to work.

But if you are more set on an iron head motor and running your intake that will not be a problem on a 3400 block (dont forget pistons are different so you will need iron head pistons, or have really low compression). All that should need to be adjusted would be the fuel pressure or perhaps jumping up to larger injectors. I went from a 2.8L to a 3.4L on my S-10 (yes I know it is TBI) but all I had to do was run larger injectors and I was fine. If you could ever find a lumina APV motor then you would be able to use that. There will be no concern with the webing in the lifter valley. There is not problem, ALL FWD motors with MPFI have the webing. It will be of no concern to you.

[sharkey]

i have no problem beleving that my computer will run a 3400, except for the distributor. without a referance pulse, the ecm goes into limp mode. im not going to rewire the car (to change the ecm, harness, i have to rip the dash out and replace everything). THIS IS WHY IM STICKING WITH A GEN 1 TOP END (im not "yelling", just making sure everyone gets the message that im not going to a gen 3 top end)

i have looked into a 3400 bottom end, and a gen 1 top end, but my option seems to be 3.4l DOHC pistons. pushrods are another issue, id have to get custom made. there is the other issue, the front mount. (i know i can get one, but seeems a bit pricey) it seems for the amount of work, it wont make a big enough power differance over a 3.1l.

if the 3.1l apv motor will work with an mpfi intake, then it look like ill be going that route then. i will likely still use a fiero intake on it. just a quick question on the ironheads: are there any castings that are better to use??? are the 2.8l ho heads the best choice to use, or should i just use the apv heads??? keep in mind these heads will go under the grinder for many hours of porting.

[TurboGTU]

Well I learn something new every day. (engine mounting bosses)

How about a 3400 block...with 3.4 bottom end...makes sence...then use your iron heads...after that...get a aftermarket roller cam to your needs with costom pushrods (if needed) and crane roller rockers. Though still a lot of money.


Anyway...on the heads. The GM powermanual says that H.O. and fuel injected heads have the larger valves. Just stay away from carburated (Verajet) heads. Iron heads also have 4 angle valve seats...so don't machine them for 3 angles...get 4. To my understaning...all iron head intakes interchange from iron head to iron head...unlike aluminum heads.

[sharkey]

there actualy is no aftermarket cam for the 3400, unless something has com out in the last few days.

so would the 2.8 ho heads be the same as any other injected head??? is there a better cating to get??? for an example of what i mean, i know chrysler big block stuff, and 904 castings are the ones to have.

[bszopi]

The 2.8HO heads are the same as the 3.1 iron heads.

[geoffinbc]

You can use any 60* V6 roller cam in a 3400 engine. Only SFI users have the problem with aftermarket cams because they need the cam sync ring.

A 3.1L may be your only choice for bottom ends then. Since you need the FWD block you will have no 3.4L FWD (excluding 3400) to choose from. But that is ok. Dont forget though if you transplant heads proper pistons must follow.

[sharkey]

did some more looking, and im leaning towards a 3.1l lumina apv motor. i can get one cheap at my local junkyard (they have a ton and being they are a vehicle specific motor, they never sell them).

[TurboGTU]

I've heard that the FWD vans have hardened cranks like the Turbo Grand Prixs do. Not too sure. On the heads...They should be all the same from the fuel injected versions. It's stated that iron heads were designed for production perposes and no extra metirial was included in the port walls for enlagemet. The chambers seem the same to me also. Theres a vane in the intake runner...which should be kept unless you want to deminish airflow.

The aluminum heads are the only ones that have their "favorate" castings. The lower compression 89-90 model are the favorates...for me....many will argue that the 3rd gen roller are the best.

[geoffinbc]

Acording to a previous post on this site the turbo motors had the exact same crank as the normal ones. The only ting that differed was the compression on the pistons.

[TurboGTU]

Well I know its a 981 crank...but I think it had chemicly harded bearing surface. The lower compression is because of the heads. The pistons are the better quality Mahle.

[Guest]

I haven't read every post in this thread in full, but I did scan through them, pretty well.

IF I was in the same situation, having an '86 Z24, and looking for an engine upgrade, I would drop in a genII (at minimum) 60*, it bolts in VERY easily, and the wiring swap is even easier, you swap the entire harness from a donor vehicle that has an ECM that supports DIS, any V6 harness from an '87 to '91 J-body will drop in, with maybe a couple pin changes at the passenger side dash connector. '87 to '90 L-body harnesses will work (What I used), but some components are located in different locations in the engine bay than the J-body and will require minimal modification to the harness. Now using these harnesses I suggested will give you MPFI (not SFI), but as you know many of us that do these swaps opt for the MPFI ECM anyway, and have few to no issues.

I know wiring can be intimidating at first, but it's not that hard, once you learn the basics and you have the proper diagrams to show you the path.

I'd just hate to see you put all this time effort and money into a genI 660 just to be disapointed, as 99% of people who do are in the end. The genII or genIII designs are far superior in potential than the genI design, well at least where the top end is concerned.

I have a genIII top end and genII internals in my genI block, I used a genI block this time due to ease of swap into my Jimmy, being a daily driver, next time I will opt for a genIII block and make the custom mount on the drivers side to do it, along with relocating the starter, due to the better oiling system and ability to easily support an hydralic roller cam, where the genI or genII design will only support a solid roller cam, without issues.

Take a good look at swapping to the genII ECM and wiring harness, it's not as hard as it may look at first.

I swapped a 3.1/5-speed into my 2.0L/auto 1985 Skyhawk in a just a little more than a weekend, this is going from a 4 cyl genI design to the V6 genII where the entire wiring harness was swapped, in fact it was never disconnected from the engine, I disconnected it at the firewall, ECM and dash harness and layed it in the engine, during the swap. Easiest way to do it IMO.

I think you'll be happier with a 3400 in the end, over any genI build-up.