91_5.7_TPI

iTrader: (2)

If a person could get a TBI setup to flow enough for a ZZ4 or similar crate engine, could a TBI be used? I know that a modded EPROM will be needed along with a bigger TB and injectors, etc.
I was just curious as to whether or not it would be a viable oprion.

TierAngst

Like you said, custom chip, bigger injectors, bigger throttle body. As long as you have those a ZZ4 shouldn' t be a problem for TBI.

91_5.7_TPI

iTrader: (2)

How about the "Fastburn" option. Same cam, just better heads.
ZZ4 = 355 hp 405 Tq
Fastburn= 385 Hp 385 Tq
I don't think that would make much difference, will it?

TierAngst

Should be fine as well.

91_5.7_TPI

iTrader: (2)

What CFM does the stock 454 TB flow? I think that a TB capable of 800 CFM should be fine one either of the crates.

Fast 355 says this:
"I can get that out of a BBC 660 CFM TBI and 68 lb/hr 9C1 350 injectors. Take a late model 454 TBI that has the 28-32 psi regulator on it, drop in the 68 lb/hr injectors and you have instant 400 HP potential."
So, get a 454 TB and some really big injectors? Maybe my idea of 800 was a little high...lol

TierAngst

extremefi on ebay sells a 750 cfm throttle body that would work well for that application. I'd probably go with something like 80pph injectors.

91_5.7_TPI

iTrader: (2)

Here is a 850 cfm TB. Twin 54mm. That would flow the numbers I would need. Where could I find the 80 pph injectors? I don't see those as a GM prodiction thing...lol. I'll search Jegs, etc.

91_5.7_TPI

iTrader: (2)

Ok, ZZ4 short block,Aluminim Fastburn heads, 850 cfm TB, 80 pph injectors, custom tune, hot cam set up... make this motor:

Horsepower: 430 @ 5800 RPM
Torque: 430 Ft. Lbs. @ 4000
Displacement: 350 cubic inches
Bore x Stroke: 4.00 inch x 3.48 inch
Max. Rec. RPM: 5800
Comp. Ratio: 9.6:1
Block: 10105123 Four bolt main, cast iron.
Crankshaft: 12556307 Forged 1053 steel and balanced to the connecting rods and pistons, 1-piece rear seal.
Connecting Rods: 10108688 Forged, powdered metal steel, 3/8” bolts
Pistons: 10159436 High silicon aluminum (Hypereutectic) with offset pins.
Piston rings: 12528817 Low tension, production size.
Camshaft: 24502586, LT4 HOT cam, hydraulic roller tappet
Lift: .525” I, .525” E; Duration @ .050: 218° I, 228° E
Centerline: 109° ATDC (After Top Dead Center) intake, 115° BTDC exhaust
Timing Chain: 8 mm single roller design
Intake Manifold: 12366573 Aluminum, dual plane, no EGR
Cylinder Heads: 12464289 Fast Burn, aluminum, includes valves and springs.
23° valve angle, Valve Diameter (Intake/Exhaust): 2.00” / 1.55”, Chamber Volume: 62 cc
Intake Valves: 12555331 1996 LT4 2.00”
Exhaust Valves: 12551313 1996 LT4 1.55”
Valve Springs: 12551483 1996 LT4
Rocker Arms: 12370839 GM 1.6:1 self aligning roller rockers
Valve Lash: Zero
Spark Plugs: ACDelco MR 43LTS Gap @ .045 for HEI distributor.
Fuel: Premium unleaded - 92 (R+M/2), in other words 92 Octane Premium pump gas.
Ignition Timing: 32° total @ 4000 RPM with vacuum advance disconnected
Firing Order: 1-8-4-3-6-5-7-2
Oil Pressure, Normal: 40 psi @ 2000 RPM
Oil Filter: ACDelco P/N PF1218, GM P/N 25160561
Oil Pan: 12557558 5 quart with PF1218 oil filter.
Distributor: GM HEI
Valve Covers: Fast Burn 385 black valve covers.

OK, so a pump gas TBI 350 making 430 hp.... hehehehe.


Anyone think it won't work?

TierAngst

There are several places that sell reconditioned TBI injectors, I'll help you find some later, feeling quite lazy right now. You really don't need a 850cfm TB, but since its fuel injection it really won't hurt anything you're just not going to gain anything over a smaller matched TB. You were doing fine with the regular ZZ4 motor but with that setup you're probably going to have a harder time getting it tuned right. I really like the sound of the ZZ4, good hp and torque, I wouldn't bother with the fastburn heads on it or going with a hot cam. Thats just my opinion though, you can do what you like with your money. What are your goals? That might help with the deciding factor. Is this car a daily driver? Are you looking to race it a lot? Do you have a ¼ mile goal? What kind of budget do you have?

BMmonteSS

You'll need alot more than a "modded prom". Please take me seriously when I say don't even attempt this without learning how to DIY tune your prom, or have a wad of cash and some one local that can tune it for you. Mail order chips might get you out of the driveway, but you'll have an undrivable pig that's no where near it's potential.

Hot cam'ed vortec engines routinly make 400 to 425 HP, decide if that expensive crate motor with the fast burn heads is worth it over a hot camed vortec crate motor.


Edit: Tier, your asking some pretty basic questions on the DIY prom board, which is fine and I applaud you for wanting to learn the ropes to trully unleashing your TBI's potential, but you may want to refrain from giving "yeah buy this stuff and your 400 hp motor will be fine" type of responses. There are very few people actually making over 400 hp with TBI, it's completely doable, but not for the faint of heart, and not for the beginner. FI is a complex beast, but when harnessed it's very powerfull.

TierAngst

I get carried away sometimes. I tried to make it sound doable but not easy which is true. Thats when I thought it'd be a better idea to ask his goals because I don't think he knows what he is getting into. I'll try leaving it to the more knowledgable guys though.

91_5.7_TPI

iTrader: (2)

I don't really need the HOT cam setup, I was just trying to see if it would be possible to tune for. I would be better off to get the engine that is offered with the ZZ4 shortblock and the Fastburn heads. It has the milder cam. Would have less Tq but more Hp. I don't know.

As for my plans, my car is a daily driver. I want it to be relatively easy on gas for the amount of power and to have drivability. To this end, I plan to have a T56 in before I get the engine with some 3.73s. I just want a car that can keep up with the LS1s in the straits. I don't want anything terribly radical, I just want mid to high 13s.

I plan to learn everthing I can about EPROM tuning. I am going to play with the L03 before getting the engine. I need to get the hardware and software to start messing with some tunes for the L03. Downside is, it needs to last till I have the money to replace it.

TierAngst

I still vote regular zz4 with the regular zz4 heads, I think it would be the best for mileage and the easiest to tune. Probably the cheapest of the 3 you listed as well. I guess I'm a little biased towards the regular version since I'm used to thinking about my 5000 pound car and torque is important.

91_5.7_TPI

iTrader: (2)

Yea, it would probably be the best street engine. Nice and peppy, but somewhat easy on gas. The T56 should make for good highway mileage. Around town won't be too hot, 'cause of my foot. I know the tune would probably be better.
The upside to the ZZ4 shortblock with the Fastburn heads would be that I could later add the HOT cam setup and get the crank power into the low 400s. But the issue with the tune and mileage comes back if I change the cam. But that would be MUCH later.

I wonder how the ZZ4 would take to a s/c....

Dewey316

seeing some of the fastburn build-ups, you can do some impressive things with it. I really like those heads.

I would start looking at this from the point of what you WANT to do with this engine, and the best, cheapest route to get there.

In the future are you going to want to shoot for ovr 400hp? Maybe switch to MPFI, or the ramjet intake? If so, get the fastburns now.

If you will be happy with the ZZ4 setup, and never want to upgrade it, go that route.

**IF** this was me, I would get the fastburns, and a hotcam, and switch to MPFI of some sort. You will have tons of potential with that motor, 500hp would be doable, with the right choice of parts, and the right computer work.

As easy as it is for people to say "yeah, TBI will support 400hp", how many people have done it. It is not an easy task. I really think for what you seem to have planned, switching induction would be smartest move at this point.

TierAngst

Its a rather high compression engine, supercharging it probably isn't the best idea. Though you may be able to get away with like 5 pounds of boost. I'm no expert (not even close) but I wouldn't recommend it.

91_5.7_TPI

iTrader: (2)

I am thinking about getting the Fastburn ZZ4 with the mild cam, running that on the TBI till I can get the money for the RamJet, then getting the cam and the RamJet and going from there.
But... doing that would save me short term money, but make the over-all project cost more. How hard is RamJet to tune/install on a Vortec engine? Is it similar to LT1-style intakes?

91_5.7_TPI

iTrader: (2)

I know. That was a joke. 10:1 won't take alot of boost. If I got some bigger CC heads or dimpled pistons... it would have a better chance.

Dewey316

I've never run one. So everything I say here is just my looking at the specs.

The ramjet appears to be more torque based than the LT1 intake. Now, the fastburn heads, use the vortec style intake mounting, so if you go with fastburns, you will need a vortec intake, which means the RamJet is one of your better choices, either that or the HSR for vortec. The right one will depend on the cam and RPM range.

Tuning will again, depend on the computer system you choose to run. But the cam is the piece that has a huge impact on tuning.

I would stop thinking about parts here. Think about how you use the car, and realisiticly what HP levels you see yourself building the car to. Also, figure out a budget, then devide that by 2, and that is what you will want to spend on the motor, because you will not meet you budget (Trust me here).

I think you are in the planning stages, instead of looking at parts now, look at the overall project, and descide where that is going. Then start looking at what options out there will best get you to that goal. Heck, it may not even be a GM Crate that gets you to the point you want to be at.

91_5.7_TPI

iTrader: (2)

I know what I want. Ultimately, I want a car that runs 12-13 in a quater. I want it to be reliable, live well, and not be giving me problems ever two weeks. I have looked at LS2s, S/C LS1s, Lloyd Elliot LT1s, twin turbo TPIs, and this stuff. I have thought about everything but a EFI 302. As far as I can tell, a TBI crate (for the next few years) will get me a realitivly installation, good power, reliability and drivablility. Later, I will probbably go RamJet with a better cam.

Dewey316

Sounds like you mind is already made up. I guess I am not sure on what your question is.

TierAngst

Now that I think about it from what you're saying the Fastburn are the way to go, it'll give you good power for now and as cast they're supposed to be good up to 500hp (read it somewhere) so you won't need anything except the new injection setup and the cam. haha I say that last sentence like its not going to cost you 3k, but you know what I mean.

91_5.7_TPI

iTrader: (2)

I think that the cam will be a later thing. Probably just the Fastburn ZZ4 and the modded TBI.

My question was if a TBI could run this engine. I know that it will be A LOT of modding, but I won't have to change the injection, which will be cheaper for now. I am in college, and really have the summer to work for these big mods. This summer will be a T56 and new exhaust. Next summer will be a new motor. I don't have my mind up made about anything. I just think that for what I can do vs what I want to do that this is a good option til I can afford the RamJet and cam, etc. I am not trying to disregard your advice. I am just letting you know what I am trying to do and what I have considered. I need all the help I can get, trust me.

Fast355

iTrader: (2)

Rbobs EBL will greatly simplify the process of tuning. The zz4 or FastBurn 385 will both take ALOT of tuning.

For the ZZ4 you will need 105 lb/hr to feed the engine at .500 BSFC and 85% Duty Cycle.

The FB385 will need 115 lbs/hr to feed the engine at .500 BSFC and 85% duty cycle.

91_5.7_TPI

iTrader: (2)

Will you explain the duty cycle part? I kinda get the rest, but not the duty cycle. Oh, and what does the BSFC mean?

Fast355

iTrader: (2)

Duty cycle is the % of time the injector is open or turned on. Then you also have pulsewidth, two seperate things. The duty cycle typically increases with RPM even though the pulsewidth stays relatively the same. Confused?

BSFC=Brake Specific Fuel Consumption. In simplier terms it is how many pounds of fuel per hour it takes an engine to make 1 HP. The more fuel used to make the same power the less efficient the engine is. Big cams, oversize ports, short strokes, big bores all typically increase fuel consumption for the same HP. 0.5 is a typical number that is used to calculate injector size, basically an average engine will take 1/2 a pound of fuel for every horsepower generated @ WOT. BSFC at part throttle will be higher in most cases, but the total HP output is lower and is covered by the same injector easily.

TierAngst

Doesn't the PPH rating change on an injector as the fuel pressure is raised? Say a stock L05 injector is 55pph at 13psi we bump it to 20 psi isn't the injector now flowing more like 80pph? I pulled the numbers out of nowhere so they aren't going to be exact I'm just say for example. What I'm trying to say can't he use something like 90pph injectors and just bump the pressure up to compensate?

Dewey316

Yes it goes up with fuel pressure.

The kicker is, that to get a large enough injector, to not go static at high HP levels, it is hard to get the injector be open a short enough time to idle. This is where a VAFPR comes in.

BMmonteSS

The only problem with the vafpr is that it's hard to get OEM like drivability with your fuel pressure changing with vacume. You can tune around it, but some things are hard to get perfect. Luckily Rbob's new EBL board and UTBI code has provisions to compensate for the vafpr so it fixes all the problems that you would encounter with stock code.

Dewey316

I know. I'm going static with my 305 injectors with the new heads.

Anyone have any bigger injectors they want to donate to the help dewey go faster relief fund?

91RedFirebird

Oh wow I've been having problems with my idle, it would be cool to idle my engine back down to 700 or lower. How does it work with the Vafpr? *sigh* if I was not so poor I would have 2 ELB's now. . . .

TierAngst

I thought it also helped it so you didn't need a vafpr and wouldn't go into static and you could still idle fine? Or am I still going to need a vafpr when I'm making say 330hp/400tq or so? I plan on getting the EBL either way. What size injectors would you recommend with the kind of power I mentioned?

91RedFirebird

Afew people have used the vafpr as a bandaid for not tuning, I don't see how it would help just make things more complicated when they don't need to be.

Dewey316

when you injectors get big enough, they cannot open and close fast enough. If this happens, you need a vafpr so that you can use more PW at idle.

TierAngst

Am I going to run into this problem?

Dewey316

Its very hard to say, it depends on the motor, the injectors, the fuel pressure, what RPM you set your idle to, etc.

TierAngst

Not sure on fuel pressure as I'm not sure what injectors I want to run. Will the 65pph "cop injectors" with bumped up pressure be enough or should I be looking into some 80-90pphs? I'd kind of like to get somewhat of a lumpy idle with the new cam... just enough so you can tell its not stock whatever that rpm idle is
In all seriousness I'd like to be able to notice the cam at idle but driveability is more important so idle rpm doesn't matter as long as the engine runs well.

DM91RS

What size injectors would this require?

Isn't this around the power Ben73's making with his AFR headed 383?

crrllmich

TBI is not limited by AIR. It is limited by its control systems and fuel. Solve both issues and TBI can run anything. If you look around enough you will even find dual 305, 350, and 454 TBIs on engines. Aftermarket systems include up to even dual 1200CFM 4 barrel TBI units. As you can see air is not an issue.

Move onto fuel. 90LB injectors at the stock pressure can flow about 375HP. If I remember correctly thats at about 15PSI. Some people beleive the injectors are capable of about 40PSI. At 40 PSI its about 146 LB/HR.

Then with the next caculation of power and involved fuel needed you can "calculate" that the max fuel limitation with a factory 454 w/ 90LB injectors TBI unit is 467HP.

I think the most important thing on making that much power tho is the tuning. I would be really looking into ways to use a different control system if your at the TBIs limits.

Another thing you can do is to contact edelbrock about converting your TBI into MPFI.

DM91RS

So......the opinion is 90 pounders at 20 to 30 psi to feed 400 to 425 HP?

Dewey316

In theory.

I don't know that anyone has accomplished this.

DM91RS

Thanks John.........

Here's some thread cuts as to what we are shooting for......

ben73........Thread.......Pushing the limits of TBI


[I think I am getting close to finding the true limits of the TBI system.

I now have the 90lb injectors at 18psi, and they are still at 96% duty cycle to give me 12.6:1 at ~5800rpm! It likes the fuel! Idle is still ok with PW around 1.0-1.1msec.. I believe 0.7 is the accepted low limit?

As far as weight-shifted horsepower calcs go, it was pushing 320rwhp, now it looks like 360 according to the few online hp calculators i play with. (3400lb '84 vette)
They also guess at ~430 flywheel, up from the previous cam's 390... assuming 18% losses...

** don't flame me on the use of these calculators, i know that attempting to calc flywheel hp is a wild guess ]



Is this the topend that is reachable?

Dewey316

If could push the fuel pressure higher, and give it enough air, that is not the limit. With enough air and fuel, there is more in there.

There is a company called 034EFI that sells a supplemntry injector driver, that is stand alone. In theory with something like that, helping to inject even more fuel, you could get more power.

DM91RS

Kinda makes something like this more attractive.

Didn't I read that the UTBI system would run a multiport setup?

Dewey316

I was looking at the Dominator EFI just the other day.

RBob

iTrader: (1)

Can also go with a 4bbl TBI or dual 2bbl TBI units.

A 2bbl TBI and 81#/hr injectors running 30 psi is good for 435 HP at .5 BSFC. Now, an engine of that nature will typically run a lower BSFC which allows even more power with the same fuel flow.

RBob.

{edit: wow, did I ever butcher 'trypcially'. fixed. BTW, the above calc is at 85% DC}

DM91RS

This seems to have answered my original question.

400ish horsepower without going multiport

crrllmich

Well can you achive over 400hp with a 670cfm carb?

DM91RS

Isn't 85% considered the safe top limit?

RBob

iTrader: (1)

Pretty much. I edited that in just to let folks know where i did the calc's. At 100% DC and .5 BSFC the HP is: 512 HP

If the BSFC is lower, say .45, and the DCis held to 85%. The HP is: 483 HP

As long as the RPM is reasonable (IOW: not sky-high) and doesn't cut into the duty cycle, this is what can be done.

RBob.