3.0 box plenum?

[Daytana]

In the junkyard not too long ago I seen a 1987 Voyager 3.0 that was similar to the later Chrysler used 6g72s but the plenum area was quite taller in comparison. Does this offer an upgrade compared to the later plenum? Thanks in advance.

[Sundance 6g72]

Typically a bigger plenum volume yields more power but noone has tested the early version of the intake... Its just a general rule. I say grab it, port it so its nice and flat on the inside and slap it on!

[Ondonti]

You arre supposed to mix and match new bottoms with old tops for a "big mouth" plenum. The old plenum has a weird tube inside. Very different.

[shackwrrr]

Wasn't 87-88 also 58mm tb

[RoadWarrior222]

52mm, they went down to ~48 sometime later, might have been 90 or 91 I forget.

---------- Post added at 10:30 AM ---------- Previous post was at 10:24 AM ----------

Oh, the injectors might be an "upgrade" in an '87 due to being rated the same pph but running lower pressure, ~27 psi... leave the regulator though, unless you wanna mod it.

[Sundance 6g72]

but then ask your self if you need more fuel... ?

[GLHNSLHT2]

87-88's were 52mm TB's. In 89 The TB went to the 46mm TB but the whole still is 52mm TB sized. I slapped a 52mm right on my mom's 3.0 V6. Matched perfectly.

[RoadWarrior222]

but then ask your self if you need more fuel... ?Well supposedly the stock fuelling is maxed around 170-180 HP and that's as far as the "bolt ons" have ever been supposed to take anyone... before cams porting or head work... The crossflow chambers in my Escort head are practically identical to the 3.0 chambers, so I'm figuring if I can replicate the work I did on that, where I got 40% gain with no supporting mods and hit the limit of fuellling, then I might wanna think about bigger injectors because even the conservative ricer math has me nudging 300... with the head work, plus classic bolt ons. If I really wanted to go balls out on development, it's not unreasonable to aim for 350 or so with 40lb injectors, cams and MS.

---------- Post added at 02:48 PM ---------- Previous post was at 02:40 PM ----------

Oh that's just the head, there's another 5% in higher compression pistons, 5% from capacity gain to 3200cc if I play with rod angle and stroke and get a potential 10% efficiency gain from that, plus 5% efficiency gains from crank scraper, and crank streamlining mods.... hmmm 400+ HP N/A... but I might be needing twin throttle bodies by then, and the intake needs severe airflow work to support that.

This is all benchracing, but suffice it to say, you won't get real far without more fuel at some point... and the +20ish of the '87 injectors should get you into the 200s without freaking out the SMEC too much.

[Ondonti]

Gotta get halfway there first RW and actually run out of fuel ;)

Be careful with the older TB's because the sensors will probably be wrong for your year 3.0. Swap party. sometimes you can just unscrew the pintle from the AIS and swap that (different sizes).

[Sundance 6g72]

i dont know of anyone besides reapers daytona that has made 170hp on the sbec without boost nos etc

[RoadWarrior222]

Be careful with the older TB's because the sensors will probably be wrong for your year 3.0. Swap party. sometimes you can just unscrew the pintle from the AIS and swap that (different sizes).Yeah, if you glance at one in the wreckers, you'll think "same" but then later realise one is male the other is female or vice versa.

[Daytana]

Ok cool. Sounds like this is a good mod and probably an even better one after some port work. I have a 52mm from one of my 3.3 projects so it all works out. Car is a 1994 Lebaron convertible btw. Picking it up tomorrow, can't wait! :bounce2:

[RoadWarrior222]

Oh, forget teh injectors for a '94 then it'll want high impedance if you get to where you need them, plenty of choices there off Fords etc, but 87 and pre 90 (?) is low impedance... we kind of get excited about finding upgrades, there's not a lot of choice.

[Ondonti]

i dont know of anyone besides reapers daytona that has made 170hp on the sbec without boost nos etc

The car had a haltech in it at some point and I don't know enough to say what system it was ever dyno'd on. That said, I don't know how much the ecu has had to do with the hp output. You would have to be running uncontrollably lean before really complaining.

[Daytana]

Picked up the Lebaron LX yesterday, the trip was a 2hr and 45 min one from Fayetteville to Yadkinville and then back. The 3.0 is screamed pretty good (even as is) and did not miss a beat on the trip. It had no problem moving the Lebaron around and would definitely eat up a stock 2.5 TI car and made my 3.3 look silly on revs. First things I am going to do is a fuel filter and minor tune up then, I will slap on my 52mm tb as well. After that it is on to the junkyard to find more bolt-on goodies such as the bigger plenum. :evil: I will post pictures soon.

[Murphy]

i dont know of anyone besides reapers daytona that has made 170hp on the sbec without boost nos etc

Josh Simon (93 sundance) ran a 14.2@97.6 in a gutted 93 sundance(est. 2600 lb), 3.0 N/A, stock fuel management

I've done a best of 15.0@91 N/A in my full weight 95 spirit

I would think mine would be around 170hp and Josh's would be a bit more.

[Sundance 6g72]

I know he ran a 14.2 but it dosnt mean he had that much power. I made 147whp with ported plenum, 52, exhaust, stock timing and thats it. Iirc, he didnt have much more than that

168peak tq

---------- Post added at 06:49 PM ---------- Previous post was at 06:48 PM ----------

Not saying its not doable... Just saying ove never heard of it done

[Daytana]

http://pic40.picturetrail.com/VOL294/1893736/23485827/400571524.jpg

Here it is, let the bolt-ons commence!

[RoadWarrior222]

I would think mine would be around 170hp and Josh's would be a bit more.


I know he ran a 14.2 but it dosnt mean he had that much power. I made 147whp with ported plenum, 52, exhaust, stock timing

Putting my vans weight a 3200 in some calcs with 0-60mph timings was telling me 165HP at the wheels with shift kit, 15* base timing and 2.5 rear mani and exhaust.... which was 52mm stock TB and big old '88 plenum... stock airbox paper filter etc... so maybe you get ~170HP with the 3* timing advance and nothing else works :D

[Ondonti]

HP calculators are not useful for finding exact numbers, just useful for comparing before and after or predicting changes. There are assumed tracting and hp dyno curve factors that make the numbers not perfectly representative of what you are getting in real life.

Its possible to move out well with less hp then you might think. I ran 15.4 and 14.8 on the same day with the same power in an n/a Spirit and the only thing that improved was me. I could have done worse then 15.4 and some drivers could have done better then 14.8.

[paduster]

If u plan on swapping intakes u will need to do the exhaust manifold in the rear cause of the egr valve

[Daytana]

If u plan on swapping intakes u will need to do the exhaust manifold in the rear cause of the egr valve

Even if it is just the upper plenum?

[RoadWarrior222]

No, but the vac hoses might be a lil different.

[Daytana]

Ah ok. I think they axed the egr after a certain year since the engine was efficient enough without it

[Sundance 6g72]

no egr here. I would just ditch it

[RoadWarrior222]

Oops, not sure if I was very clear, no you don't have to change to/from EGR to swap the plenum. But there's some difference in the vacuum connections I think.I'm a bit vague but I'm thinking there's 2 nipples on the neck of the older plenum, where there's one and a tee on the newer plenums. Though there's some differences between applications and years on the newer plenums so not sure whether you'll end up with an extra hole to plug, or need a tee to get all your lines connected.

[MC#4]

Ah ok. I think they axed the egr after a certain year since the engine was efficient enough without it

I thought the older ones were EGR-less? I have a 94 and a 96 plenum here and they both have EGR.

[Sundance 6g72]

think it depends on the state laws

[Ondonti]

older = egr free. You can just remove the pipe and put a piece of flat metal under the clamp for the pipe, then swap the plenum.

[Daytana]

Cool works for me.

[Murphy]

i covered the EGR on my manifold and plenum with a piece of 1/4" steel and some exhaust RTV.

if your swapping the plenum you should consider installing some plenum spacers.