ls six

I was thinking of swapping the complete top end vortech heads and all and running it off the TPI computer and most of the stock harness.


The IM is an aluminum base with composit top.




It uses a single large TB and the injectors are internal.

The Injectors and various sensors should be interchangable with the 90+ TPI bit's.

I'm looking for an affordable way to get past the TPI's top end limitations.



Heres some info .

http://images.search.yahoo.com/image...sigb=12u1st2ro

Pocket

iTrader: (24)

You contradict yourself

Stock vortec uses a 2 piece intake:
Aluminum lower and plastic upper

Marine vortec uses 2 piece alum intake

All of the benefits you want sound more like the marine version, but even that has limitations

Exerpt from an article on them
Regardless if you agree with his opinions, the fact remians that the intake-much like TPI- is a restriction. You can confirm this by going on any chevy truck/SUV forum and searching "vortec powerband."

Next, wiring
All sensors will NOT interchange with any TPI, infact very few of them will
A closer match would be 90-92 V6 wiring as they used the newer GM ends, but why not use the vortec wiring since you're already taking the intake

A better solution
http://store.summitracing.com/partde...5&autoview=sku
http://store.summitracing.com/partde...5&autoview=sku
Something along these lines
Port injection is retained, power band is whatever intake you buy and there are multiple options, wiring can remain stock TPI if you want it to based on which TB you use and sensor arrangement, and lastly, they are cost effective with proven results

I would suggest you research ALL of the common intake swaps in this forum

ls six

Your right about the ultimate restriction of course.

I was having computer issues so I didnt go in to detail with my thoughts on the truck vs marine IM's.

What do people use for the TB on those IM's?

The late model vortec TB looks nice and proabably out flows our stock one.

I have thought about the TBI throttle body but it looks worse than ours as far as flow area.

I have seen adaptor plates as part of EFI conversion kits that attach TBI TB's to square bore IM's but nothing for what I want to do.

1989GTATransAm

iTrader: (3)

Last year I did an upgrade on my 2000 Tahoe with the L31 motor. I replaced the 350 motor with a 383. There is an upgraded fuel injector assembly available that uses real fuel injectors versus the poppets valves on the factory unit. I used it.

There is also an aluminum plenum spacer available that goes between the aluminum lower intake manifold and the composite upper manifold. Gives much more plenum area and allows the air to move around much more freely. I used it.

There is a guy locally here in SoCal that opens up the throttle body and installs a new blade. He also eliminates the "flow restrictor" that is attached to the factory throttle blade. Helps things quite abit. I did that.

For my Tahoe I also went the K&N cold air intake route, cam, smog legal headers and some stealth upgrades to the exhaust system. Runs great with much more power and gets the same or better gas milage. Passes California smog to boot.

Regarding using a TPI computer and harness I guess you could but you would have to get/make wiring adaptors for the sensors and the fuel injectors. Also use a TPI distributor.

What is your goal for doing this?

sol_searcher

Go here lots of info on l31 marine im conversion

http://www.pacificp.com/forum/viewtopic.php?t=317

Fast355

iTrader: (2)

The stock L31 intake, cam, and heads fell over on its face by 4,500 rpm in my Express van. With a ported L.I.M., ported heads, lightweight LT4 retainers and springs, and Production LT4 cam, I motored on to 5,800 rpm and could have gone higher had it not been for the black boxes 5,800 rpm restriction.

FWIW, I actually test fit a Vortec intake with a TBI distributor and it fit fine and had plenty of adjustment. I even ran the setup on a TBI ecm and modified wiring harness, on a test stand. It would run better with the TPI ecm though.

ls six

Wow thanks for all the interest. I looked around the forum and didnt see any refferences to this IM.

I'm just looking for a cost effective way to get past the TPI's top end limit's.

Even ported and with all the aftermarket bit's available the TPI manifold is limited by the extreme runner legnth and settups like the stealth ram seem expensive.

I have thought about using a carb type mani setup for EFI using the TPI ecu and harness but I dont know what TB to use.

A TBI throttle body will work if you drop the injectors and the TPS and IAC should work since they are all contemporary with the TPI parts. They will also have the TV linkage needed for the auto trans but they dont look they'll flow as well as the L31 TB.


Thanks I'll read up tomorow.

Very good stuff there. I figured the stock IM was limited RPM wise but figured that a plenum spacer would help. It's nice to know I wont have to fab one.

I like the short runners though. Some work on the base section should give good results. Raised radiuses or even horns inside a larger plenum and relocated injectors are top of the list.