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Eh?
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Awesome thread, one question about exhaust though.
Eventually I will be running long tube headers, 2 magnaflow high flow cats and 2.25" tubing.
I am either considering to run an x-pipe and 2 magnaflow mufflers with tips or a single dynomax DI/DO muffler into a dual rear side exit.
Which will give me the best low end torque and overall power?
 

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Im walking on sunshine!
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5,647 Posts
Discussion Starter #102
Awesome thread, one question about exhaust though.
Eventually I will be running long tube headers, 2 magnaflow high flow cats and 2.25" tubing.
I am either considering to run an x-pipe and 2 magnaflow mufflers with tips or a single dynomax DI/DO muffler into a dual rear side exit.
Which will give me the best low end torque and overall power?
Headmens are just fine for the money.
 

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GMFS Senior Member
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3,237 Posts
Every combination imaginable has been tried and eventually thrown in the trash. The biggest problem with the tbi setup is fueling. To oversimplify the issue, in order to have enough fuel at high rpm you need injectors too large for the engine at low rpm.
 

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I got a big block tbi that sets on a factory adaptor that has a spreed bore,the same as a quadra jet carb. Im wanting to use it on another adaptor that go from a spreed bore to a holly type set up and put this on a weiand high rise intake. I have a 89 350 stock, I know the heads arnt good but the intake systems are not worth a grap either so untill i can get a better set of heads im just woundering what wound i have to do beside a little wiring to the tbi, i know these motors and computor rely on temp,vacume and a oxy sensor, but they dont seem to know the air fuel mixture like a sfi system thats in my 94 lt1 camaro I hope some can help me with this just wanting to try some thing new the ultimate tbi set up really seemed to help but my motor still seems to be needing more air to run a little better and i also have the big block 80-90 lbs injector but i may stick to the 50 lbs injector due to not having the upgraded fuel pump. serious minded help only no sarcastic idiots....Thank you my bow tie friends
 

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AllOffTopic.com FTW!
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I got a big block tbi that sets on a factory adaptor that has a spreed bore
Can you provide more details about your truck? I'm going to need one of those adaptors for replacing my quadrajet with TBI and I'd love to get it from a junkyard, but I'll need to know what year, model, and engine to look for.
 

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The tbi i got came off a 7.4 454. 1988 i think it was. the the adaptor that im going to buy is a mister gasget and then bolt the two together. what other info do u need of truck the motors all stock except i do have shoty headers with flow masters, taylor plug wires,tbi modifiation
 

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AllOffTopic.com FTW!
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:shake: Thanks, I think that's all I need...I just wanted to know where I could find a factory spread bore intake -> TBI adapter in a junkyard.
 

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is there a good tbi to lsx manual out there?
 

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Don't have a reply, have a question. I need a prom for a modified 95 C1500. It has a 97 Vortec engine with 9.8-1 compression, comp cams 218/224 duration .495/.503 lift cam, comp cams 1.6 roller tip rocker arms, GMPP tbi-to-vortec intake bored to match a big block tbi, big block injectors, 18 psi fuel pressure regulator, 60 psi fuel pump, pocket ported vortec heads with 1.6 exhaust valves, and edelbrock shorty headers with correct egr tube. I can't be the only person to have used this combination. Someone else must have the ultimate prom that makes it all work right or knows where to get it.
 

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Multiple GMFS owner
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2,098 Posts
I got a free block and rotating assembly with about 24,000 miles and a pair of head with about 20,000 miles. I want to build a decent engine for my 88 Sierra. I am going to go through and spec everything out and see if it needs to be bored or if I can hone it and reasemble with new rings, bearings, gaskets and so on. I will need a cam, intake and fuel delivery system. I know its old technology but I would like to stick with TBI to see what I can get out of it. I plan to do a stock bottom end rebuild but would like to get some decent power and torque out of this because eventually the truck will end up being lifted 6" with 35"s on 20"s, nice light weight combo. I am thinking of this cam package http://www.summitracing.com/parts/CCA-K08-413-8/?rtype=10 because it comes with the cam, springs, lifter, timing set, seals, locks and retainers. I would just need a valve job done, can get seats and valves ground free, and to get push rods. I was thinking of the GMPP intake for TBI but has the Vortec intake bolt pattern, http://www.summitracing.com/parts/NAL-12496821/. For the throtle body its self I was going to find a 454 TB, rebuild it, put in an injector pod spacer and a TB spacer also. Exhaust I'm thinking Doug Thorley Tri-y's to a single 3" pipe to the back of the cab, a Cherry Bomb Extreme, a 3" pipe dumped over the axle with a 4" tip. Probably email TBI chips for the tune. The transmission has been rebuilt with the TCI race master overhaul kit and a B&M shift kit anout 2,000 miles ago, I'm going to add a Vette servo also.

I have no idea for ignition system, I know that Accel has a direct plug in box/coil set for TBI trucks, but would I just be fine with an upgraded factory style ignition system?

The headers come with a y-pipe, does it work on lifted trucks? What size is the y-pipe outlet? Single exhaust doesn't bother me because it will be dumped under the truck. A single 3" exhaust should be plenty correct?

Overall I wondered if anyone could help me decide on differant parts or more upgrades to help the plans I have already.

This is a copy of my post in my thread I made, if any one can help that would be great
 

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Just got my serial data plug and monitored my 94 full size blazer 355 cu in, comp cam 12-249-4 and on a 1/2 mile drive it showed 252 knock sensor counts and retarded timing.. I'm new to the monitoring. Is that Bad? True dual exhaust flows, fresh rebuilt tbi, rebuilt trans 2 years ago, new distributor, and sensors. Fresh motor just built and installed this year...
 

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Can y'all please enlighten me on what to tune on my 99 5.7l 350 Tahoe? I'm about to purchase some 33.12.50x18 cooper stte and some rims. And a 4" rcx lift. Everything else stock except true dual straights and a CAI. Thanks for yalls help
 
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