USSCaprice

I am planning the following motor

Cheap: goodwrech 350, L05 TBI system what would I need to hook it up?

Stroker: 1350$ speedomotive 383 stroker short block, vortech heads 500$, cam and lifters 200$, intake 200, 200 for roller rockers and springs, and for 2450 I have a 400hp engine I can get a complete L05 TBI system with the computer, harness and injectors from someone. What would I need to do to support 400 hp with TBI?

Can the stock pump take it?

What injectors should I use?

What would I need to do to the computer?

Has anyone on this forum made 400hp with a TBI?

The 200hp goodwrech engine would be $2000, The 400 hp stroker would be 3000$ but no warranty/ may guzzle gas and how do you pass emissions with a 400hp stroker? I could claim it was my 'tweaked" L05 and as long as I keep cats and air pump all the emission would be in place and the engine is newer than the car... could it pass a tail pipe test?

BillD91RS

No one that I know of has made 400 HP with a TBI system. Read the post about what Car Craft and you will see what they had to do to get to 395 I think it was. Basically you need the biggest TBI unit and Injectors you can find.

Bill

Chuck!

The Lo5 tbi is the same as the 305 LO3 tbi. Both have 1 11/16" bores. If you want to come close to that and stay under some sort of budget you'll need a Holley 670 tbi or a GM 454 SS tbi, both of which have 2" bores. Plus you'll need 80 pph injectors. At that point you'll definatlly (without a doubt) need a custom burned chip. Id pick up that hobby if I were going to drop that much money on a block.

Why buy a crate 350 when you're going to junk everything on it? If you are going to go the 383 route Id just get a junk yard block, have a good shop check it then do the work on it. Check around, the shop may have a good 383 setup they do. I know where I got my machine work done they have a very solid street/strip setup thats about $1500 I believe.

Stock Vortec heads will not flow enough for 400 hp, you might look at the Fastburns though. $850 assembled and they're aluminium. You'll need a pretty mean cam, I'd call comp and tell them your plans including the fact that you'll need to pass emissions. Any engine with a good cat that's running in good tune should pass a sniffer test.

That'd be a hell of a battle to build but it'd be very rewarding when you're done if you get it.

Brent

iTrader: (1)

Cheap: goodwrech 350, L05 TBI system what would I need to hook it up?

Don't bother with the $1250 fits all goodwrench 350. Its got dish pistons, 8.5:1 compression and mediocre cylinder heads. If performance isn't your goal and lowest price is, ignore what I said.

Stroker: 1350$ speedomotive 383 stroker short block, vortech heads 500$, cam and lifters 200$, intake 200, 200 for roller rockers and springs, and for 2450 I have a 400hp engine I can get a complete L05 TBI system with the computer, harness and injectors from someone. What would I need to do to support 400 hp with TBI?

You'll be the first to document 400hp with 2bbl TBI. You'll need the biggest injectors, a new fuel pump, a 454SS TB and roughly double the fuel pressure.

Can the stock pump take it?

Not a chance.

What injectors should I use?

17112560 and a vacuum reference FPR capable of atleast 25psi

What would I need to do to the computer?

Major custom tuning.

Has anyone on this forum made 400hp with a TBI?

no

could it pass a tail pipe test?

Yes


Its gonna be some work to get the factory TBI to drive and play nice. Still interested?

Brent

iTrader: (1)

Didn't one of the rags do a hot cam/vortec 350 that made 420hp for $2500.

Chevyman69

I was kinda thinking along the lines of Brent with a set of AFR 180 heads and keeping it a 350, maybe put in the stroker crank and whatnot but I would like to stay with 350 cubes. So you guys are basically saying there is no one that can build 400 horse and similar torque from a TBI system( the GM 2 bbl system anyways). I would love to have something like that in my truck but the way it sounds this system can't handle it. I have heard that the computers in these vehicles cannot really be mapped accurately for a fuel curve extending above 4600-4700 rpm, is this true. And of course 350 horse naturally aspirated is the limit or somewhere in there relatively. An engine with 400 horsepower and a torque can be built with a 650 cfm carb and a cam that won't kill everyday driving by any means so you are I assume its not the cfm that is lacking( 675 from a 2" bore TBI), its the tuning that won't allow it. I would like to hear from someone who can honestly answer this question and has a truth to back it up. If the TBI system will not allow it I will eventually change my system, probably a manifold with an open large throttle body and 8 injectors but would still like to keep this thing TBI.

Brent

iTrader: (1)

Chevyman69: You have a 88-92 truck? If you haul/tow anything and you don't want to change you axle ratios you might consider a 383 with 330-350hp. That's as much hp as the current GM big block offering and it won't be as hard to tune. That will be approx 130hp over you current status. Nothing to sneeze at.

Trans mods will probably be required too as the 383 will be able to climb grades without downshifting.

AJ_92RS

Many a magazine has proven they will. You have to add better valve springs and to do that you have to enlarge the spring pockets, grind down the height of the valve, as well as grind down the OD of the guide. I suppose after that's done you COULD say they're not "stock".

A 670 cfm TB is flowed at 3.0"/Hg since it's along the same lines as a 2 barrel carb. 4 barrel carbs are flowed at 1.5"/Hg. If you convert the 670 cfm @ 3.0"/Hg to 1.5"/Hg then the 2" TB only flows ~475cfm @ 1.5"/Hg.

I'd say that's enough of a variation to loose some upper RPM HP.

AJ

Chevyman69

So ok lets say now since we are dealing with a 2 bbl TBI versus a 4 bbl carb there is a difference( I agree with that). So that is to say then with the GM TBI system the only reason for the lack of horsepower or torque is due the lack of CFM and the fact the computer will not handle it either. The reason I keep asking is yeah i can build a 330 horse 383, big deal, I can buy a 330 horse 350 crate and make that run too( BTW my curent motor is not bone stock either its got a fair amount of mods and i am happy with it for now). I plan on if I went about this engine modification the drivetrain would be done too, i have a longbox fullsize 4X4 1/2 ton, with 373's and yeah i tow. I am fully aware that maybe some of you think its a truck so he doesn't know what he wants, but i do, I know with a carb I could have my cake and eat it too, so to speak, and the same is going for TBI. I do not want advice on what to build, or what i want or any of that, not to be rude, but I have sort have made my choice. I just want to know that if this type of a powerplant is buildable or not with GM TBI, if not, i will make my own system.

Chuck!

Im interested in seeing those mags and what cam choices they're using. Do you have any specific issues?

NJ SPEEDER

i think thgat info is on scoggins dickey's website soemplace. it was a vortec h/o motor with LT4 hot cam, 1.6 rockers, torker intake, and a 750 carb.
with a 670cfm tbi you can get the same peak hp number, it may be a few hundred rpm further up because of the smaller air inlet. you woudl definately see soem good torque if you worked on getting the timing tanbles set good.

later
tim

AJ_92RS

Car Craft did one in the Sept. issue. Although I just missed buying it. My wife works at Barnes & Noble and she just called to have them hold it since they're taking them off the shelves tonight.

IIRC, they made 406HP. I'll get you the specs tomorrow.

Other than that I have 5 issues of CHP in front of me right now that each have an engine that made over, or damn near 400HP.

In chronological order they are....

Jan. 2000... 395HP @ 5,900 RPM with Comp cams XE-268H, Edelbrock intake, 1 5/8" headers, and a slight pocket port. I know a pocket port is not stock, but all they did was clean up the bowls and back-cut the ex. valves 30* which is now the standard for the Vortec heads. Then they added 1.6:1 Comp Cams roller rockers and went to 402 HP @ 5,900 RPM. Finally they switched to 1 3/4" headers and got 409 HP @ 5,900 RPM

April 2001.... Same exact combo as mentioned above except they used a Road Demon 625 cfm carb on 87 octane gas, no pocket porting and made 390HP @ 6,000 RPM. The above combo used a 750 Holley, but on 93 octane.

Nov. 2001.... Using a Hot Cam Kit, Speed Demon 750 carb and no pocket porting, with a single plane intake made 422 HP @ 5,700 RPM. The same combo with a dual plane still made 412 HP @ 5,600 RPM

July 2002.... A GMPP 383, Hot Cam Kit, Holley 750 DP, Air Gap intake, and untouched Vortecs made 412 HP, and 416 HP @ 5,600 RPM with 1 3/4" headers.

August 2002.... Same motor as above with Comp Cams XE-282 Hyd. Roller cam, Speed Demon 750, Weiand Elec. water pump, and back to 1 5/8" headers made 449 HP @ 5,400 RPM.

That's all I could find within the 5 minutes I looked. CHP is the only magazine I subscribe to, so I'm sure many other publications have done the same but with other cams, etc.

NOW do you think the Vortec heads will flow enough? The Fast Burn heads will produce more PEAK HP with the right cam and need no mods at all to do so. But I guarantee that they will not produce as much LOW RPM torque or get as good of gas milage. They're racing heads, plain and simple. They're not made for street/strip engines.

AJ

PaulD

The original question had to do with making 400hp with TBI.

Is anyone going to mention the limitation that only 2 injectors have? To get 400hp, you'll need 200pph total injector flow. 80# or 90# injectors will not cut it unless you start to jack up the pressure which will bring you back the the vacuum referenced regulator or trying to tame the injectors to idle at higher static pressure through programming.

Chuck!

Thank you, I stand corrected. There must be a lot going on inside these heads that make them great other than their flow. The stock numbers only flow 225/149 @ .500 lift and I wouldnt think that'd be enough to touch 400 hp, but I was wrong.

AJ_92RS

Good advice. I wouldn't think either if I had the choice... it's makes my little head hurt.

No problem though on the 400HP part. I would have never guessed it either. When the magazines first started using them for test engines, they kept it around 350 HP because they thought there's no way $400 heads can produce any more than that. Especially stock castings with little 170cc intake runners.

Well they finally bit the bullet and said, "What the heck. Let's see what kind of HP we can sqeeze outta these little suckers!!!"

Amazing what you THINK (there's that word again ) won't happen does happen after you actually try it.

AJ

Dyno Don

iTrader: (7)

Paul, you hit the nail on the head. I tried it ...
"383"- Sportsman II heads (ported)- ZZ4 cam- 1 3/4 headers-454 TB 1.6 rockers 80# injectors.

On the dyno, everytime we put it under load with RPM's it leaned out to 15-1. I gave up and switched to the Holley multiport system.
Don>>>

Chuck!

I think ( ) I need to get a larger tbi to take advantage of these heads! If you have a site or a rag or something that explains why the vortecs make the power they can Id love to give it a read. Is it the chambers or what? Sheez I should know more about the **** Im bolting on to my car!

Dyno Don

iTrader: (7)

Oh, and not to mention SpeedoMotive sucks! Their quality and customer service is absolute rock bottom. I have a personal bad experience with them, and a good friend had a similar bad experience. They are the McDonald's of engine builders, the bottom of the barrel.

Dominic Sorresso

One other thing to remember with these magazine motors. Not one of them is dyno'd in a car! They use electric water pumps, no emissions gear, and no other power robbers like p/s, a/c etc. Usually, we're comparing the rear wheel hp on a real car to the chassis dyno hp on one of these motors with no other encumberance.

CamaroDriver

And your point is?

Won't simply changing to a higher stall torque converter change the RWHP? Or changing gear ratio in the rear end? And what if I don't have the A/C on? And I don't have to run emissions because it's a dirt track car?

They would be adding WAY too many variables to the RWHP rating if they were to do such a thing.

JPrevost

Large fuel lines, BBC (80 or 90) injectors, a vac.AFPR and the right tuning could support 400hp. The fuel tables in the gm_ecm don't stop, they only go up to 6400rpm and from then on it's anybody's guess. With some source code tweaking you could probably extend the tables. The timing only goes up to 3600rpm, after that there is a constant degree per 1k rpm, I believe stock is 3.5^ which is crap and should be set to 0 on a performance car (timing should all be in within 3600rpm!!!!).
With the vac. AFPR and a cam that has decent vacuum you can idle with the best of em ~10psi range and under WOT have it go to 20+.
One trouble with the TBI computer is that it's got slow datastream refresh rate and that is starting to bug me REAL bad.

Dominic Sorresso

Camaro Driver,

What I was suggesting is that it may be possible for a TBI motor to test out to 400hp under the same conditions as the mags use.
Certainly their procedures allow for comparison of the motor in isolation, but as you described, quite a few other mitigating circumstances could change the outcome when that motor goes on the road. That's all my point was about.
On the other hand changing stall speed and rear end ratios shouldn't effect the measurement of rwhp, at least not materially.

badburban

Im just finishing my 383 build up and will probably start setting it back in place this weekend. I have a 1994 K1500 Suburban. The motor according to desktop dyno makes 340 hp at 4500 rpm and 490 ft lbs of torque at 2000 rpm. I bought a holly TBI unit becasue I was told it would give me more than enough fuel for it and If I were to go with the 454 unit with 90 pph injectors it would essentially flood the motor and It would take alot of Tuning of the computer chip on my part. I personally thought it was . But i kept hearing the same thing over and over again from different people so I bought the holley. Now that I am reading this I am doubting more and more that the Holley will be able to supply enough fuel for it. What are your guys thoughts on this.

Dyno Don you are running a zz4 cam in your 383. I bought a zz4 cam for mine to and then my con rods hit the cam so I had to have Lunati grind me a small circle base cam. I would have really liked to run the zz4 cam but it didnt work out. So I have a zz4 cam if anyone is interested.

Josh

CamaroDriver

What I'm saying is the only consistant way for a magazine to test an engine is on an engine dynomometer. That's the only way THEY can get a nice solid result from what mods they've done.

All RWHP on a chassis dyno is measured from acceleration. If you change the rate of acceleration by changing gears or torque converter, you WILL get a higher RWHP reading. I 1000% sure of it.

Dominic Sorresso

[QUOTE]Originally posted by CamaroDriver
What I'm saying is the only consistant way for a magazine to test an engine is on an engine dynomometer. That's the only way THEY can get a nice solid result from what mods they've done. [QUOTE]

I have no disagreement with this. Did I say I did?

Quote:

All RWHP on a chassis dyno is measured from acceleration. If you change the rate of acceleration by changing gears or torque converter, you WILL get a higher RWHP reading. I 1000% sure of it.

Isn't that why the dyno operator asks for your rear axle ratio?

Slade1

I've taken my car to 2 different dyno tests and changing gears do not change rw torque or rw hp.

A dyno meter measures mph acceleration per rpm.

When gears are altered, mph gain per rpm alter, its a give and take deal and the program sees right through gear changes. You can do a dyno run in 2nd third fourth, doesn't matter, I did mine in second and third, I still had same max torque and same max hp.

The reason behind this is simply this, if a dyno reads mph gain per rpm, gears are irrelevant.

In second gear you will pull to a higher rpm say instead of 4000, you can hit 5500 before it dies off. The only thing is, you gain less mph per rpm than you did in third gear. Result is identical torque and hp. Peak will still be 4000, although hp will stay more flat after 4000 slightly, max torque is still made at whatever the cam dictates as that's a physical limitation of cam more than anything else.

The only thing that will look different is the steepness of the curve, the time it takes to get to to a certain rpm. That's why gearing is not a factor of hp, rather a major factor of the 1/4 mile et.

Brent

iTrader: (1)

GM offered a BBC TBI engine kit that offered roughly the same HP. Search the www for HT502. I think Pace has it listed on their site.

They used the 17112560 75lbs/hr BBC injectors and the Vacuum reference FPR to make 340hp. The VRFPR delievers 18-19psi at WOT which raises injector flow to approx 104lbs/hr. The kit also comes with a new fuel pump and custom PROM.

PROM tuning will be necessary to get it right.

badburban

Thanks alot Brent. I know prom tuning will be needed which is fine cause I do it myself. I meant that the part that the bigger injectors will be way to much for the motor and it would "flood" it is what I meant was bs.

Josh

hectorsn

That's too bad that you are so sure of it because it is untrue. As a matter of fact, if you go from a stock converter with a 2.73 gear and change to a 3000 stall and 4.10 gear you will probably lose about 3-10% on a chassis dyno. You may go faster on the track but that's why we don't race dynos. The reason is simple, it takes more power to turn more gear and *most* higher stall converters aren't as efficient. A good one will make as much or slightly more power. Same thing goes with the tires you use on the dyno. A taller wider tire will use up more HP but will probably help traction and reduce E.T. Such is the paradox we call "the automobile".