454tbi

[alberta91crew]

So, i have a 91 Crew that has a stock 454 TBI and I am wondering what i should do to make it better? Headers, Air intake? What can I do and What SHOULD i do new to TBI so i dont know what the limitations are

Thanks

[SCOTI]

Air in, air out. Start w/an Edelbrock Performer TBI intake. Freshen up the peanut port heads w/a multi angle valve job & mill the heads slightly if possible to slightly bump compression. Then add a better cam & better exhaust (headers).

[pig rig]

like scotti said but if you dont want to spend the big money on heads and intake
cheep rout put an adjustable pressure regulater in the TBI and a fuel pressure gauge in so you can see what your doing. bring the pressure up on your injectors will help it atomize the fuel better.
put an MSD 6al box on it with a higher out put coil and open up the plugs to 40. and put an electric fan on it

if you go to ss454 site you'll find lots of info on the getting HP out of the TBI engines

if you want to swap out the intake dont buy the preformer Tbi you can use the std performer and then take your water donut to a machine shop and have it milled flat and it will give you a good seal that will save you a couple hundred that way

[SCOTI]

Originally Posted by pig rig

like scotti said but if you dont want to spend the big money on heads and intake
cheep rout put an adjustable pressure regulater in the TBI and a fuel pressure gauge in so you can see what your doing. bring the pressure up on your injectors will help it atomize the fuel better.
put an MSD 6al box on it with a higher out put coil and open up the plugs to 40. and put an electric fan on it

if you go to ss454 site you'll find lots of info on the getting HP out of the TBI engines

if you want to swap out the intake dont buy the preformer Tbi you can use the std performer and then take your water donut to a machine shop and have it milled flat and it will give you a good seal that will save you a couple hundred that way

What I didn't like about the standard cast-iron q-jet style intake I removed from mine was it had oval ports; not the slightly smaller peanut ports. That's an immediate disruption in the intake flow of air to the heads (if they're TBI/PP heads).

I'm using the Edel TBI intake w/the smaller peanut ports so that they match the heads intake port which should yield a smoother, better velocity transition. If I had true oval port heads, I would use the standard Performer intake & factory TBI adapter. I'm also by-passing the coolant loop on mine.

[alberta91crew]

Originally Posted by scoti

air in, air out. Start w/an edelbrock performer tbi intake. Freshen up the peanut port heads w/a multi angle valve job & mill the heads slightly if possible to slightly bump compression. Then add a better cam & better exhaust (headers).

where would one get the heads done? At an engine shop or just by new heads?
Did you do anything with the computer?
IS THAT 454SS.COM?

[SCOTI]

Originally Posted by alberta91crew

where would one get the heads done? At an engine shop or just by new heads?
Did you do anything with the computer?
IS THAT 454SS.COM?

A local 'high volume' type place did the machine work. My motor seized up so everything was gone through & I replaced my pistons w/flat-tops too (minimal change, but it should still help). No computer mods thus far but I haven't got it running again yet to 100% determine if it would benefit from some tuning.

Another thing I'm doing is switching to a heated O2 sensor vs. the stock unit.

[JCampbell]

Don't mind me...I'm just subscribing.

[pig rig]

Originally Posted by JCampbell

Don't mind me...I'm just subscribing.

your alive campy how you been


If you put headers on you'll need to put a preheated o2 senser in. because the exhaust is flowing past the o2 faster and its takes longer to heat up and it will stay in close loop longer. but I have therory about doing that a preheat o2 was made to preheat by the ecm now I've had a couple go bad on me so my therory is its not made to be hot all the time like it is when its add like what we would do 1 wire to the ecm 1 wire to switched power.not to the ecm to switch it on/off like it was designed to. so its on and hot all the time. thus burnning it self up so to speak. maybe someone that realy knows can shed some light on this

[JCampbell]

Originally Posted by pig rig

your alive campy how you been

I’m good. Livin’ the dream.

[jimbonice]

I wouldn't be too concerned about the cast iron oval port manifold disrupting the flow on the peanut ports. I've seen a number of dyno sheets in the hi-po magazines where it hasn't hurt performance, but actually increased the power levels in mild street builds. It might go against what we all believe to be common sense, but sometimes life is like that.

cheers,

[SCOTI]

Originally Posted by jimbonice

I wouldn't be too concerned about the cast iron oval port manifold disrupting the flow on the peanut ports. I've seen a number of dyno sheets in the hi-po magazines where it hasn't hurt performance, but actually increased the power levels in mild street builds. It might go against what we all believe to be common sense, but sometimes life is like that.

cheers,

Good discussion guys. I'll challenge the statement above..... Increased the power level vs. what alternative?

We could debate the theory of it does/doesn't work, but the point is moot. We know the 'mis-match' will function, but you would only maintain/improve the velocity by matching the ports (meaning you won't hurt it). I'm not saying you're killing the power w/the mis-match.

That being said, if you're spending the $$ for a new manifold & you have no plans to get a larger TB or do a carb swap, why not get the one w/matching ports?

[D.FENS]

Originally Posted by pig rig

but I have therory about doing that a preheat o2 was made to preheat by the ecm now I've had a couple go bad on me so my therory is its not made to be hot all the time like it is when its add like what we would do 1 wire to the ecm 1 wire to switched power.not to the ecm to switch it on/off like it was designed to. so its on and hot all the time. thus burnning it self up so to speak. maybe someone that realy knows can shed some light on this

Not sure if the element in a heated 02 stays on all the time or not. I know a guy who writes ECU code so I'll ask him.

You could do a relay in the circuit, triggered by a temp switch to turn off the heating element when the motor reaches xxx degrees.

BTW there's supposed to be an "upgrade" cam for the 454SS motor that is said to work really well with the TBi. I don't have the PN in front of me but the guys at 454ss.com should be all about it.

[SCOTI]

Originally Posted by D.FENS

Not sure if the element in a heated 02 stays on all the time or not. I know a guy who writes ECU code so I'll ask him.

You could do a relay in the circuit, triggered by a temp switch to turn off the heating element when the motor reaches xxx degrees.

BTW there's supposed to be an "upgrade" cam for the 454SS motor that is said to work really well with the TBi. I don't have the PN in front of me but the guys at 454ss.com should be all about it.

There are several. GM had one that's been discontinued but Lunati, Comp, & Edelbrock all have similar grinds.

[wyattglock]

I had my heads reworked at a local performance shop that has been around for over 20 years. My biggest piece of advice is to ask the shop if they try and press out the original steel guide, or if they use the tool to cut it for a bronze sleeves. The bronze guides will help your valves last much longer than if you dont have them. For a reference, my heads cost me $319 out the door. This included magnafluxing, hot tank clean up, .005" shaved off the heads, bronze guides, new seats, and a three angle valve grind. Price will obviously vary, but that is just what it cost here in Indiana.

[INSIDIOUS '86]

look through this article http://www.carcraft.com/techarticles...ild/index.html

[SCOTI]

Decent power but the cam wouldn't work w/TBI.

[BigBlocksRule]

Before you throw a bunch of cash at your stock peanut port heads, try to find some old 396 closed chamber heads. They'll flow a lot better, even with stock valve sizes, and you'll bump your compression by a full point. Clean up the bowls and short turns and get a good valve job.
As for bronze guides, I have several sets of big block heads in my shop with well in excess of 100K miles apiece, guides are still within spec. I don't dislike bronze, but if the factory guides are fine and still within spec, there's no reason not to run 'em. Roller rockers will help 'em live since the tip of the rocker doesn't "scrub" across the valve tip and push it back and forth in the guide.

[SCOTI]

Originally Posted by BigBlocksRule

Before you throw a bunch of cash at your stock peanut port heads, try to find some old 396 closed chamber heads. They'll flow a lot better, even with stock valve sizes, and you'll bump your compression by a full point. Clean up the bowls and short turns and get a good valve job.
As for bronze guides, I have several sets of big block heads in my shop with well in excess of 100K miles apiece, guides are still within spec. I don't dislike bronze, but if the factory guides are fine and still within spec, there's no reason not to run 'em. Roller rockers will help 'em live since the tip of the rocker doesn't "scrub" across the valve tip and push it back and forth in the guide.

396 heads.... The cast iron (affordable) version of Edelbrocks aluminimum 'hi-compression' performer heads. I was really surprised @ just how low the OE compression ratio is. Seems a mid 8's to 9:1 motor should still tug a load w/o detonating on pump gas.

[meter swinger]

Subscribed.
What about the stock exhaust? Go to duals and a better cat? Dont intend to hijack just im in the same boat.
Posted via Mobile Device

[SCOTI]

Originally Posted by meter swinger

Subscribed.
What about the stock exhaust? Go to duals and a better cat? Dont intend to hijack just im in the same boat.
Posted via Mobile Device

Air-in, air out. Anything that helps w/that, helps.

A larger single exhaust w/some headers & high-flow cat would be better than manifolds & smaller, restrictive OE converter, & small OE pipe size. Duals would work too (if you can).

[BigBlocksRule]

Headers, baby, headers...high flow cat, decent turbo mufflers and you're set.

[BigBlocksRule]

^ yeah, it used to be common for guys to use a rectangle intake with oval port heads. Mort mismatch is a nightmare but it works...somehow.

[FritzA]

For a lot of good TBI info, you should check out http://tbichips.com/

Follow the link on the left to Good TBI Mods and then to 454SS on the bottom. He mentions some specific cam grinds in there.

It's the basics as stated before: Air In and Air Out along with enough fuel and spark. Start with the low hanging fruit like open air cleaner, stronger coil and dual exhaust (even without headers). Oh yeah, make sure the fuel filter is fresh, an old filter is death to the tbi engines.

Then step up to a good cam (matched to your intended driving purpose), manifold and a better fuel pump. Are the valve springs as bad on the tbi BBC as they are on the SBC? Another good upgrade when you switch cams. Now is also the time for a modified chip (again matched to your intended driving purpose).

Finally I would go to a bored throttle body. If you come across a good deal on some heads the yes, jump on them.