fbird92

I have a '92 firebird with a 305 tbi motor. Edelborck has come out with a multi port kit to convert 350 tbi motors in trucks and SUV's into multi point. I was looking at getting a 350 crate motor putting in a mild cam and roller rockers other wise keep it basically stock. Get the multi point kit that is said to add 80 horse and 80 lbs of torgue. I would get a computer from a like a '92 truck for it. I was looking to keep it EFI and stay away from carb. I think this would be pretty cool. Just wondering what other people opinions are out there and if anyone has already done it.

ACCLR8N

iTrader: (8)

Thats not a bad idea at all. It should be fairly simple to install following their directions. The only negatives are price and I think the Edelbrock system is batchfire. Still going to perform better than a 305 TBI motor.
A TPI convertion would probably be a few hundred dollars cheaper (and I think look cooler when you open the hood), but aquiring all the necessary used parts, wiring and installation would be harder.

five7kid

iTrader: (14)

Make sure your crate 350 has better heads than the TBI engines had (not hard to do, but you need to watch what you're getting).

five7kid

iTrader: (14)

Out of curosity I went to the TBI forum and seached on "edelbrock multi-port". I got about 25 hits. Only one person (of the posts I read - sorry, I didn't read them all) said they had it (that particular person has a van, not a 3rd gen) and said he wouldn't recommend it. When asked to elaborate, he didn't respond.

I then remembered that I drove a truck that had that conversion done. The owner was very proud of it and bragged on all the power it had gained with the system (and Edelbrock headers, and other supposedly performance-enhancing mods). I thought the truck was a dog, but I may just be spoiled by what I've got. Of course I had never driven the truck before the conversion, either.

I have driven my brother's '93 C1500 with factory TBI on basically a rebuilt L98 engine. I thought it was the better running of the two. But, again, I hadn't driven my brother's truck when it had the stock LO5 in it, either.

fbird92

I didnt know if anyone else has seen this system and what they thougth about it. It sounds good in writing, more power and improved gas mileage so why not. But i have not seen it personally in a vehicle before just seen the guys on horse power tv install it in a truck. so i have kinda been curious as to if it would work with an install of a 350 truck motor and computer.

five7kid

iTrader: (14)

I wouldn't go out and look specifically for a 350 truck motor. Actually, I'd look to avoid them. See the "better heads" comment above.

I can provide the link to the rebuilt L98 that my brother got if you're interested.

It appears you will need the truck ECM and TB in order to use the Edelbrock kit. I would think you could also go with the TPI ECM, for that matter.

If you do it, be sure to post back here (and the TBI forum) to let us know how it goes.

fbird92

Oh ill deff be posting my results once i have it done. yea if i could get a link for that rebuild motor that would be awesome. Im trying to get this motor over 300 horse. Would any 350 small block work? i know there are some crate motors i can get around 3k that have over 300 horse.

Fast355

iTrader: (2)

Weird, don't recall being asked to elaborate and not doing it, but it is possible. I tend to be a busy person, read a post, then forget to reply.

There are several problems with the edelbrock MPFI kit.

For one the factory 19 lb/hr injectors are a severe limitation for 300+ FWHP. They are only good for about 260 FWHP. Stock TBI injectors are good for around 230 FWHP at the stock 12 psi fuel pressure. Drop a 30 PSI regulator on it and you are set fuel wise to 325 FWHP with the stock injectors.

The idle in Edelbrock's chip is set for around 625 RPM and tends to be very rough. They even state that the rough idle is normal for their kit and it will improve when in Drive. It does slightly. It quivers so bad at idle you would think that their was a non-balance shaft 4.3 under the hood. I have since read the Edelbrock chip with my prom burner and found that only relatively minor changes have been made from the GM prom. It is FAR from ideal the way it comes from them.

Here is further proof. These are ENGINE dyno numbers from OffRoad supplied by Edelbrock using a 1992 Chevy Suburban 350 TBI and their kit, up to and including their performer TBI cam and aluminum heads.

Dyno Data
RPM-----1: HP/TQ------2: HP/TQ------3: HP/TQ------4: HP/TQ
2,000---114.1/299.5---120.0/315.0---120.3/316.0---123.4/324.0
2,500---142.0/298.4---144.5/303.6---147.5/309.9---151.1/317.4
3,000---166.5/291.5---171.4/300.1---177.4/310.6---180.3/315.7
3,500---182.6/274.0---197.7/296.6---204.7/307.2---215.9/324.0
4,000---189.9/249.3---214.5/281.7---223.8/293.8---246.8/324.0
4,500---193.5/225.8---213.6/249.3---224.6/262.1---263.1/307.1
5,000---186.1/195.5---202.9/213.1---213.6/224.4---266.5/279.9
Legend
1: Bone-stock '92 TBI 350 with exhaust manifolds, catalytic converter, and muffler
2: Edelbrock MPFI conversion (PN 3502), no other changes
3: Add Edelbrock TES headers (PN 6660), no other changes
4: Add emissions-legal Edelbrock Power Package: Performer Centerbolt heads (PN 6085), Performer Plus cam kit 0.398/0.442 lift, 244/264 advertised duration (PN 3702), TES Exhaust System (PN 6824)



I built a 10:1 355 out of a 4 bolt main Vortec 350(ZZ4 forged crank, Vortec PM rods, and Flattop Hyper pistons), Dart 180s, PRODUCTION LT4 cam, 2" bored edelbrock 3704, BBC TBI with 68# injectors at 30 PSI, 1 3/4" x 3" headers, 2 1/2" duals, X-pipe, 2 1/2" cats, 2 1/2" duals with flowmaster 40 series mufflers and custom prom tuning using the $0D PCM code.

Here is what happened, I played with the transmission shift points to do a full 2nd gear pull from low speeds. Just under 300 RWHP through the exhaust. Better than 325 RWHP with open cut-outs. This engine IS going into a F-car, just need to find one. Keep in mind these are REAR WHEEL numbers, not Flywheel like theirs. Take my numbers and divide them by .85 at peak HP and .90 at peak torque, to get somewhat close for the comparison. (Roughly 380 FWHP(15% loss at peak HP)/340 FWTQ(10% loss @ peak torque)0




Here is the source for their dyno numbers
Edelbrock Performer Multipoint EFI - Off-Road Magzine


READ through this post. You WILL get MORE for LESS.

https://www.thirdgen.org/forums/tbi/...i-buildup.html

five7kid

iTrader: (14)

I posted the link & details here https://www.thirdgen.org/forums/engi...an-i-find.html
Pretty much, yes. But, not with just any 350 head.
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Ah, but we got you to now, didn't we!
That makes a lot more sense to me than the Edelbrock multi-port. Certainly with their PROM.

robertfrank

iTrader: (27)

I still have one question reguarding the multiport set up.Instead of using the prom that came with the edlebrock would using the EBL with the extra injector upgrade be a better choice? I think with some 24lb injectors,the EBL,vortec's and a 50mm tbi unit it would be a pretty strong setup,with the right tuning of course.