2.8 tbi base with 4.3 tbi

[Blue89rs]

In my quest for more HP, I've looked into doing this swap. We all know that the MPFI intake on the RWD/FWD 2.8/3.1 is not good at producing HP, and all of the "custom" intakes mearly mimic this design and aren't that much better for the cost (Truelo). So, to minimize runner length I've opt'ed to go to the TBI setup.

Has anyone ever done a flow for this intake setup? I have all the parts to make the swap happen, but I can't find any information as to if it would flow higher numbers than the MPFI. I'm sure it will, but numbers would help.

Ref flow numbers: http://www.thirdgen.org/techboard/v6...ed-intake.html

[Blue89rs]

http://www.4x4wire.com/tech/60degreeV6/index.htm

These guys claim 40+HP from the base 125HP of the TBI 2.8L. That means it would be pushing 165HP from 160ftlbs. Does this sound feasible? The 4.3L TBI could support 300HP, so it would be possible to get over 200HP NA from a 3.1L.

I'm more convinced to do the swap. I'll let you know what numbers I can come up with for airflow or HP.

[Blue89rs]

Found a guy named Mabru on S10forum with the same setup and mild cam. Claims 170hp 180ftlbs at the wheels with a 3.4L. Thats 204/216 at the engine with 20% drivetrain loss. Is this close to what the 3x000 FI systems can push for power?

[geoffinbc]

It is a descent gain but there is NO WAY IN HELL you will gain 40HP. The only whay that will happen is if you do a cam swap with headers and a good exhaust couple that with the 4.3L TB and a chip tuned well and then maybe you might get 40HP on a 2.8L.

Or you could swap to a 3.4L

[Blue89rs]

The 40hp seemed a bit optimistic I'll agree. But do you think that it would flow more air than the MPFI setup? The 4.3/5.0/5.7 all use the same 1-11/16 (43mm) dual bore TB which sounds like it would out flow the stock MPFI single 53mm. Or should I find the dual 2" TB?

Could just anwer my basic question of, will a TBI intake outflow a MPFI intake?

[ignoreance]

On the 2" You may not be able to port the venture of the manifold out that big... I pulled my manifold to 1.78 and I'm not sure the other .2 is there on this manifold.On the TBI you can pull ever thing out and leave the butter fly in and port it down then polish it up on both sides giving you a bigger flow down.... Main thing is you can pull the center out of the manifold an open it up around the EGR area... there is alot of matieral there that can be removed... But if you have an extra manifold I say plow forward. I just didn't want to buy another TBI Manifold I would love to know for future that it can be pulled to the 2.0" mark. I pretty much knife edged the center of the manifold below the EGR opening and have mabye a two inch hole in the center between the two sides of the manifold so it will cross flow if they need more A/F to one side. Thats what I did..


I don't think anyone has done a MPFI VS TBI

[Blue89rs]

I may have a lead on the 2" TBI. My buddy might have one floating around his shop.

I've been wanting to dyno my V6 car to see where it is befor and after the manifold swap. Should be interesting.

[ezrollin]

Some of us have bored the throttle bores and installed a 4.3 with good results,would require some brackett fabbing for a f body.

[Blue89rs]

http://www.thirdgen.org/techboard/v6/393150-stock-vs-ported-intake.html

runner 1: 157.8cfm
runner 2: 143.6cfm
runner 3: 141.3cfm
runner 4: 149.3cfm
runner 5: 152.4cfm
runner 6: 143.1cfm
intake/TB assy: 418.7cfm

Since a 54mm should only flow 330cfm, I may benefit from going to the 4.3TBI setup.

[ezrollin]

You have a private message

[Ed_Mc.]

I have a 3.4 in my Trooper along with a Holley Big-Bore TBI (same throat bore size as an S-10 4.3 TBI) and bored-to-match intake manifold. The setup seems to be more than enough for the engine.

There's an S-10 Dude at the S-series.org 60 Deg V6 forum who dyno'd something like 187 RWHP on his similarly-equipped 3.4 in a 2WD S-10. It also had headers, free-flowing exhaust, hotter cam, and 1.6:1 roller-tipped rocker arms.

That should be the equivalent of something close to 200 HP at the crank, I'd expect!

[ezrollin]

Can't you port the mpfi and add a bigger tb?

[Blue89rs]

not really. the neck of the intake is too small. I've tried to put a little bigger TB on it, but it just doesn't work. The design of the manifold is poor and its difficult to port.

[geoffinbc]

Are you stuck with iron heads?