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Old 01-08-2011, 10:27 PM
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what performance heads for sbc to make around 450 hp

Hi everyone, I have a questions for and about my motor in which heads i should use. first of all I have 91 silverado with a 350 tbi its been bored .060 over, a crane cam 114132 with a .440/.454 lift, edelbrock shorty headers, jet performance stage 2 chip, electric water pump, dual electric fans, throttle body spacer and a edelbrock air cleaner. I also have a edelbrock torker intake to use and adapter to use carb intake to tbi. the truck also has 3:73 gears. also approx. how much hp and torque do i have now thanks.

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Old 01-09-2011, 03:01 AM
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Welcome to the site . This needs to be in the engine section.


Cole
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Old 01-09-2011, 05:42 AM
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without some serious help, a TBI engine really can't get over 250 hp.. and with the mods you have listed, like the electric water pump and throttle body spacer, suggest somthing used with higher RPM operation, not what you would expect with a truck especially the electric water pump... the best you could do is a set of Vortech 5.7 heads, with a Vortech TBI intake, and that will be about as good as you can get. depending on how well your truck is running now, it might net 225-250 HP. could touch 300 hp with tuning, but the TBI really can't suport more than that

my guess is right now, it's probably at 200hp, depending on the type of pistons used for the rebuild

post the question in the correct ( engine ) section and you will get others insight
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Old 01-09-2011, 01:54 PM
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Nowhere near 450 hp with that cam. Do a search on the engine forum and punch in 450 hp smal block and see what comes up. Been beaten to death.
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Old 01-09-2011, 04:54 PM
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Not an expert but you'll need a lot more air moving through that engine to get to 450HP.

1. ditch the electric water Pump. to much worry to gain a legitimate savings in HP unless you plan to run at 5K+++ RPMS and with a TBI you'll never get enough Air.

2. Bigger TB. What I remember is the stock injectors and TB can only flow enough to get you into the mid 200's Not to mention the heads stock lacked a good intake path (again memory) which is partly why the intake CFM could get away with being so low.

You are far better off looking at building for torque 1200k-3500k where the engine will be driven and can survive the low CFM intake.

I''ll make an assumption here.

Start with a perceived Vortec 350 at 290hp add, tb spacer 10hp, ad headers 15hp, bump compression must good for 25hp add a stage 2 chip and I get 340HP right???

Stop Magazine racing.... all that only adds 10HP.

The motor stock 87-95 TBI 350 made I believe 205 or 210HP
305 made 185HP

Couple things to do in your situation

1. Increase Throttle body size - IE, 454 TB (much more flow) or Send your current TB out to be hogged out and bigger injectors added or buy the Holley system which gets you to 670CFM from summit. Still limits you to about 335HP - 385HP tops. You will need to tune this thing very well no plug in chip will handle this.

2. True Vortec heads (these are the 96+ 350 only heads) Can be had cheap i bought my last pair for 50.00 included a usable block. 200 got them fully rebuilt.
These bolt on match your intake design and will add around 15-20HP out of the box compared to the early 90's design.

3. Roller Lifters worth about 10 real parasitic HP. (about 175.00 for an average set)

Now cam I am assuming you are running a roller cam (block should have had that in it factory) you should try to mimic the ZZ fast burn 350 from GM use their cam and with a set of mildly tweaked 062 vortec heads you should be fine.


Next step will be to ditch your FI (fuel injection) so you can get air through the motor. just my .02 I mean no ill regard I have been and met many people with huge hopes only to find reality hurts. Just take where you are and move to the next step.
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Old 01-09-2011, 05:59 PM
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whew, i have a 91'Z/71 i read somewhere the tbi 350 put out no more than 200hp, the swirl port heads are NOT hp getters, and doing the vortec heads and vortec tbi intake i looked in too, it wouldv run me around 600 bucks just to get my hands on them, then to bulid the heads bc they came from the junk yard 200-300 bucks there, i looked at it this way, going from 200hp to 225-250hp for 900-1000 bucks does not sound good, i thought about going carb when i rebulid mine, rv,towing,4x4 cam, flattops, headers, diff heads like vortecs, for this i could do for alil over 1000 bucks and get 300hp or mayb a touch more hopefuly.....good luck
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Old 01-10-2011, 10:42 PM
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very helpful

okay should I go with the 454 tbi or some good heads first. also if i went with the 454tbi what would i have to change. and if im not mistaken the tbi thats on mine they also used it on the 4.3 "that sucks" as far as cfm. how much would the 454 tbi increase my hp and torque. also how do i move the forum to the engine forum. thanks everyone.
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Old 01-10-2011, 11:55 PM
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Budget????

Well those numbers can be achieved but the big catch is BUDGET? There are
alot of options out there for the 350sbc, but your going to have to ditch the TBI seriously. If your looking for a daily driver you will have to look into a torque beast. Now if you want to get more serious than that, there are other options. You can of course stroke the sucker!! (383) Since the 383 is so popular, they are now WAY MORE AFFORDABLE. I build these alot for my customers. If you go all out on that 383sbc you can get 475HP easy. If you want more radical you can build a 350sbc with higher RPM range and then you will feel the cost go up like crazy. You will have to do a stall, vacum pump, single plane intake, different cam, Bigger better heads, long tube headers, good carb, go full roller motor, high volume oil pump, bigger oil pan, very good set of piston rings with forged internals. And trust me that's not the end of it yet. Your truck's drive train will feel the pain. You will have to invest into HFI flex plate, stronger U-Joints, Rear end gears, and bearings. I built one of these for my Nova and I broke just about everything under there. I had some CHEAP 3.52 gears and they didn't hold up. There really is alot involved into building a serious motor. Just all depends on YOU. My .02 for a budget build a stroker and you will love it. Get some vortecs like the other guys suggested. This is another topic that has been beat to death LOL
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Old 01-11-2011, 07:45 AM
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The stock the TBI you have flows 400CFM, good for about 225 HP.

If you buy a 454 TBI you'll need to rebuild it $$$. You are better off buying a Holley 670CFM. That will get you up to about 350 400HP.

Vortec Heads and a roller cam will be the best money you can spend, Rollers are expensive but are worth it 20-30HP over flat tappet

and keep moving forward, and buy a programmer or dyno time.
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Old 01-11-2011, 09:23 AM
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even the stock 454tbi from the 89-91 454 SS trucks only made around 250-275hp, what made it decent is the fact that it made around 400tq. i dont think that the 454tbi woud be a good idea, it might be able to get you to 300hp. your best bet is to get rid of the swirl port heads (said to be one of the worst production heads GM ever produced) and find a set of vortecs or better yet at set of RHS pro torkers, and switch to a carb
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Old 01-11-2011, 09:34 AM
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450hp! That's doable, but it will be pretty radical street engine, and not really a daily driver. I've got a lot more engine, cam, and carburetion on my .040" over 327, and I doubt I'm hitting that 450 hp mark.
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Old 01-11-2011, 11:15 AM
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A roller cam with the same specs as a flat won't net you an automatic 20 to 30 HP by virtue of being a roller, it's in the grind. There are benefits and some gains you realize with rollers, don't get me wrong, but that much gain is too much to expect.
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Old 01-11-2011, 11:50 AM
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Cheapesrt way I can think to get there with TBI- get the 454 TBI and have it reworked, ported, and smothed out. Flat top pistons with vortec head that have a god valve job and some bowl work. 224/224 roller cam with about .570" net lift. 1 3/4" long tube headers. RPM airgap maniold with your adapter welded and matched to it. You'll need a good tuner too.

If you spend the time to get perfect fit and finish when assembling this engine it can make your power goals. You're looking at about 1-2 grand in parts depending on what deals you can score.
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Old 01-11-2011, 11:56 AM
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I agree its in the grind but on a block that came factory with a roller cam and is setup for it. Its counter productive IMO to use flat tappet.

On my Ddyno, I tried a few options and it always read 20ish HP and tqft more with a equal lift over a flat. Granted they had different overal specs but with a roller you get away with a lot more.

My fault for poor wording of the entire thing.
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Old 01-11-2011, 12:24 PM
How fast is fast enough?
 
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Computer dynos are worth less than a guess by someone who has ran a few races IMO. Roller cams are worth power but your "evidence" carries little merit, don't rely on a computer simulation. There is plenty of real data to support your claim.
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