I have a 1991 Trooper 2.8l V6 LS I have put a hi-flow 2.5ö exhaust, a throttle body spacer, and put injectors in from a 4.3. Currently the engine is being rebuilt. Overview: three angle grind, bored out pistons, slight upgrade cam shaft w/ adjustable Edelbrock sprocket, roller (tip) rockers, bored out a few other things. IÆm also putting in a new clutch for good measure. Any suggestions about this, has anyone had luck re-mapping the ignition with a jet chip?

Question1:
Headers: I found a likely fit on Edelbrock's website part #'s 68972 & 68973 are for the same 2.8, but for s-10/s-15's, I wonder . . .

Question2:
K&N and airRaid do not make air intakes for this engine. Other than a custom job, anyone have any ideas on getting a cone filter in there? There is not much room after the throttle body spacer.

I welcome any suggestion or comments.

well, first I beg you to never, ever use a K&N or similar Dust Ingestion System or other gauze filter. Second, read this before blindly abandoning the factory style filter. http://www.bobistheoilguy.com/airfilter/airtest2.htm

Presumably you can avoid up to 0.018psi of power-robbing restriction!! That's like installing a 0.018psi supercharger! OMFGWTFBBQVCR!!!!ONEONE!!

"I've owned several K&Ns and they are easier to service. If you are buying a high performance filter for airflow, K&N is tops in this test." quote from the web link. It's a bit presumptuous to assert that I am going into this "blindly." That study was done with water, so he is making some assumptions when comparing H20 with air. I like the concept though, gets the ideas going. No air intake kit is made for this engine that I know of, so I may very likely keep things stock. thanks

Cool ..... I didn't know there was an adjustable spocket for 60* v6s. part number please <img src="/forums/images/graemlins/smile.gif" alt="" />

Googled, no luck, closest I found ....

http://www.edelbrock.com/automotive_new/mc/valvetrain/timing_chains.shtml

Recommendation: if you're putting the $$$$ into a 2.8 rebuild, including boring the block, why not also install a 3.1 crank? Minimal increase in cost, you're already going to have to buy new pistons and have the rods installed on them.

I used Sealed Power H562CP pistons for a RWD cast-iron-headed 3.1, along with a 3100 crankshaft. Any crank out of a 90's-era 3.1 or 3.4 will work, most common is the #981 casting and it doesn't matter if the reluctor ring on the crank is slotted, since the Trooper motor doesn't use a crank sensor thru the block.

The Sealed Power pistons are teflon coated and have very tight fit in the bores, for less piston slap and great cylinder sealing.

At any rate, it'll make for quite a bit stronger motor, especially with the power mods you're doing. The 2.8 has the same bore as a 3.1 and the heads are the same so all you really need to do the upgrade are the pistons and crank. Everything else including crank bearings would be identical to what you'd be using for a 2.8 rebuild.

Just a thought.

BTW I used a K&N on my old 2.8 hot-rodded Trooper motor, which is still running strong. That filter was transferred over to the 3.4 LS with no issues whatsoever.

P.S. the clutch that came with a Rodeo/P'up 3.1 4WD is larger in diameter and would be better in a performance application. The one I used for my 3.1 'stoker' project works great.

G'luck with the rebuild..........ed

The test was of airflow not water, he was using a water manometer, which is a pressure differential measuring device that uses a water column to indicate the pressure change before and after the filter.

In other words, no water was passed through the filters, the water is part of the instrument.

while my opinion is still to avoid "cone filters" as I don't believe they provide any realistic benefit...

you might want to look under the hood of an early 90's cadillac with the 4.9l engine. There might be your snorkus. <img src="/forums/images/graemlins/kewl.gif" alt="" />

I'm not positive either way wether using a presumably larger injector (as in the 4.3L) is going to be positiv negative or no effect on your engine buildup. The way I understand it is the computer dictates your fuel metering during closed loop operation via your MAP, coolant, 02, tps and rpm measuring. If you use a larger injector aren't you going to force the engine to run the injectors at a very low flowrate to adequately fuel the engine? Don't forget your engine mods won't require more fuel than a bone stock 2.8.

He's definitely going to be flowing more air thru the motor with all the mods planned. If you use 4.3 injectors with 2.8 TBI on a bone-stock 2.8 it'll run terribly rich. But maybe not so bad with a breathed-upon motor.

The Holley Big-Bore TBI I had on my old hot-rodded 2.8 worked fine. It did feel a tad 'over-carbureted' but not to a drastic degree. The airflow improvements were more noticable at the midrange-to-upper end.

The ECM should be able to meter OK with the larger injectors when in Closed Loop. However with a modded motor, fuel demand on cold starts is quite a bit higher and you can experience lean-surge until Closed Loop. The problem you have with a 3.4 conversion. Larger injectors or increased fuel pressure usually eliminates this problem. Again, the tendency to do this will most likely be less exagerrated using the smaller-bored TBI.

I experienced cold-start lean surging with my 3.1 buildup, had to break the spot weld on the adjustment collar of the stock 2.8 TBI and jack the fuel pressure up. Doesn't surge now and runs a lot better in Closed Loop, too.

Anyway, if it does run too rich with the 4.3 injectors he can always put the 2.8 ones back in. Lots of room to play with, you can use one set of injectors or the other and adjust fuel pressure to suit.

BTW, I wasn't paying close enough attention to the K&N discussion <img src="/forums/images/graemlins/sleeping.gif" alt="" /> My K&N is not the cone filter for a cold-air setup, but the standard drop-in replacement. To get more air in the stock air cleaner and not make a lot of noise, I spliced in another snorkel, chopped from an old S-10 air cleaner. The new snorkel has the hot-air-inlet side blocked off, and the stove tee'd into the stock heat stove vacuum line, such that after the engine warms up, both snorkels open. Makes a big diff in airflow and virtually as quiet as stock. Lots better than a flipped lid!

Hey just to throw something in, I got a flowed 4.3 TBI with guage and regulator built onto it. The place is R.V. Morse Machine out in California. The nice man's name is Vic, Mr. Morse, and they can be found at rvmorsemachine.com or call him at his number on the web site. This guy has forgotten more about injectors than most so called experts will ever know. Flowed TBI(15% over stock 4.3 TBI), gauge and regulator were $50 to $60 cheaper than the Holley. With my motor this T.B.I. should be just the ticket.And on top of everything else you can brag about having a custom built T.B.I. JMHO.