gregl316

iTrader: (1)

My motor is a 330hp GMP crate motor and I want more power. My question is
Can a TBI support it?

I have all the goodies. A GMP intake, MSD ign, Headers, Built 46mm TBI w/68# inj., Vacuum compensated adjustable FPR, A Corvette fuel pump, no smog, and I still only got 252rwhp on the dyno when it was tuned. But since then I have changed from a built 700r4 to a T5. If that makes a difference.

Can I swap the cam and intake and up my fuel pressure,and get what I want with out a complete redo?

My tuner says a TBI won't support 300/350 rwhp. He says go Carb. You guy on the form have got me here from being lost I know you'll get me the rest of the way.

I am running with a lot of 5gens and my goal is to smoke them. I already can out handle them now I have to be faster.

Greg

Formula 305

454 or Holley TBI, more CFM should up your output. I forget what the cutoff is, but the stock small block TBI is probably the choke point and your limiting factor at this point.

I think I read on another thread a while back that the smallblock TBI was only good for like 300HP (Crank HP if I recall correctly)

midias

Some good reading here.

https://www.thirdgen.org/forums/tbi/...ower-will.html

thomas1976

IIRC you have not yet swapped the cam, which is commonly reported to be the huge restriction of that engine.

For racing I would also go with a set of aluminum heads, weigh less and are less prone to detonation.

300rwhp is probably close to the limit of the GMPP intake.

A pair 80#hr injectors in the pod, a decent intake manifold, combined with a decent roller cam, a set of aluminium heads, around 10:1 CR, a decent tune and decent exhaust, should make 350rwhp easy.

gregl316

iTrader: (1)

Thank you for your response. Now one more thing.

Send me a list of what to buy and where. It is killing me that the new Camaro is faster then me.

Formula 305

You're a big boy, you can do some homework and decide what parts you want yourself & then source them yourself. Nobody needs to spoon feed you a list of part numbers & vendors.

gregl316

iTrader: (1)

Sure I can, but I don't want to make any mistakes.

Should I keep vortec heads?
What brand of heads?
Why aluminimum can't I port my steel ones?


I want to learn from others.
I realize I'll need;
heads or at least work
cam preferably complete roller
intake
new injectors
a tune.

I have good exhaust.

now I go to Summitt and fill my cart.

spicyskater

you ever race your car at the track...if yes ...what is you 1/4 mile time...v6 gen 5 Camaros run about 14.40 as far as v8 5 gen you will start braking your drivetrain befour u outrun them...vortec heads are great heads don't undarestamate them ...here is a good roller cam http://www.jegs.com/i/GM+Performance...FU8LMgodTWMAMA
change the springs too ...stock springs are weak wont let u go pass 5500 rpm...try double pumper or 4 barrel tbi

thomas1976

You a re looking for some serious horsepower, probably time for some aftermarket aluminium heads.

first you should figure out the required combustion chamber to get around 10:1 CR with your block https://www.uempistons.com/index.php...tors&type=comp

Fast355

iTrader: (2)

Personally I would work on the suspension, chassis and driveline to get the car capable of hooking and surviving the increased power first.

I have had pretty good luck with the LT4 Hotcam in a a few setups.

http://www.hotrod.com/cars/project-v...ckage-install/

gregl316

iTrader: (1)

My suspension/chassie and drive line is done. I have spared no expence on this car. I have an a chance to buy either a 2014 engine and trans out of an SS or a ZL1. I just don't have 10 grand laying arround.

Should I keep Vortec heads?
I found some Bridox heads and intake.
I can go rite to Summit and get it all.


I will talk with my tuner and see what he has to say.

gregl316

iTrader: (1)

So I should buy new heads just so that they are alumium?
Should I stay with Vortec heads? That limits the choises.
What about cam? Roller for sure but what specs?
Which intake? I am thinking a RPM intake air gap maybe.
Some one point me in the rite diorection.

midias

Whats your budget?
How much power you want to make?
What is your desired RPM range and use?


The correct direction is here.

gregl316

iTrader: (1)

Well as usuall the budgit is high. I don't want to spend any more then 5 grand or I might as well put an LS in.

I am making 252 to the wheels now out of a 330hp rated crate motor. But that was going through a 700r4 to my Moiser 12 bolt with 373 gears with 275/40/18's. Now I have a T5 trans and I haven't retuned it. I want to make a real 350/400 to the wheels. I think my drive train will put up with that.

I have a stick so I want to beleave the RPM range should start at 1500 and go to 5500.

Any help would be great. I just don't want to just buy parts all ***** nilly not knowing if their to much or not enough.

Thanks Greg

Bigfoottpi11

-

thomas1976

The aluminum heads will allow to take advantage of more CR and are less prone to detonation during racing.

The great thing about vortec heads are good flow #'s due to the increased height of the intake ports, but any respectable aftermarket cylinder head will flow good to better than vortecs.

A cam in the .490-.500 lift, 112 LSA, 210-215 duration range should be nice with aftermarket heads. Something like the CCA 8-501-8. Could play with comp cams camquest, to get an idea.

I would go with a single plain intake but not air gap, if keeping TBI.

gregl316

iTrader: (1)

Should I keep the Vortec heads?
It would be cheeper just to go to regular heads.
Since I have to get an intake too.

thomas1976

Going by the 9:1 CR with 64 cc cylinder head volume description of the 330hp crate engine, brings us to an approx 16 cc dish piston.
Meaning it will require a 54 cc cylinder head volume to get up to 10:1 CR. Standard cylinder head volume of 350ci heads is in the 62-64cc range.

If you feel confident to work on the engine, you could swap the pistons, 7cc for 64cc heads or 8cc for 62cc heads. Though the whole rotating assembly will need to be rebalanced with the new pistons.
Maybe at that point it would also be a good idea to deck the block so that you can use a thicker 0.039 head gasket like this http://www.summitracing.com/int/part...make/chevrolet otherwise the only choice you have is this 0.015 in. cylinder head gasket http://www.summitracing.com/int/part...1094/overview/

I would not keep vortec heads if I could go with a set of budget aftermarket aluminium heads http://www.hotrod.com/how-to/engine/...#__federated=1

gregl316

iTrader: (1)

So throw the Vortec heads out. I'll just buy a new top end and cam

Will I be able to keep the TBI?
How about the holley 4bbl TBI?
Will it work with my stock computer? or does it have it's own?
Or should I just throw in the towle and put a carb on it?
I want about 350 to 400rwhp. And I want decent mpg.
When it was running good last summer I got over 20mpg hwy.

I run with a bunch of guys with 5th gens and I am pissed that they walk away from me. Anyone can buy a new car and it's fast and so could have I. But I'm a 3rd gen guy and I like making my own.

thomas1976

Some way or another you will have to resolve the low CR pistons, though looks like Dart makes a 49 cc combustion chamber cylinder head http://www.summitracing.com/int/part...111f/overview/ this should bring CR to around 10.6:1, which would be perfect. EDIT I just noticed it is an iron cylinder head, bad luck! Something similar made of aluminium would be perfect.

With a reasonable cam like the one mentioned above it should brake in the 350+ rwhp easy, though it will probably peak at around 5700rpm.

Someday I will try this out http://www.summitracing.com/int/part...make/chevrolet

A pair of big TBI injectors, VRFPR, tuned EBL is all you need to fuel it.

Though first thing to do is figure out what pistons are in the 330hp crate engine, CR is important.

Fast355

iTrader: (2)

The 300 and 330 hp 350s have 12cc dished pistons with metric ring pack ala L05 or L31.

Street Lethal

iTrader: (16)

Your tuner, ehh? Where exactly is your fuel pressure for you to expect 300-350-RWHP from two 68# injectors? I would also be curious to hear where your duty cycle is with the 252-RWHP that you were able to get as it is with those small injectors, I'm assuming 100%, unless your fuel pressure is up there...

thomas1976

How did they come up with such low 9.1:1 CR, did they use a thick gasket?

Fast355

iTrader: (2)

Everything I have seen is advertised at 9.4:1. Its the exact same long block save cam/lifters they use as the Marine 350 and a L31 Vortec 350. The pistons are typically .015" down the hole and GM runs a .028" compressed head gasket.

gregl316

iTrader: (1)

I have the number for the motor.
the pistons are cast aluminum and 9.1:1

The number for the engine is: 12486041

sabien

Oh,you want horsepower. I don't know why you went with a crate motor. You should have went with a forged small block with a c/r of around 8:1. Aluminum heads, set up with a procharger F 1 blowing through a "Fast" 30401 fuel injection system. Just my thoughts on good horsepower.

Fast355

iTrader: (2)

Its the same block, crank, rods, pistons, heads and head gaskets as a L31 and it is 9.4:1 advertised in a truck or a boat. I have had one torn down to the bare block. Only difference between the 330 hp 350 and a L31 is the provision for a mechanical fuel pump on the crate engine and a hydraulic flat tappet 212/222 iirc cam rather than the 191/196 roller of a truck or a 196/206 roller boat.

Fast355

iTrader: (2)

http://m.summitracing.com/parts/nal-12530283

How the same list of parts magically become 9:1 in a GM crate engine is a mystery to me. I have crunched the numbers of an engine I had torn apart and it came out at something like 9.39:1.

gregl316

iTrader: (1)

Dude I am just reading from the engine build sheet. I punched in those numbers into the internet and it came up with the build sheets.


http://www.gmpartsdirect.com/perform...ATID=1099.html

Fast355

iTrader: (2)

I hear you man, I think we are both caught up on something that doesn't really matter too much in the grand scheme of things. 1 full point of compression going from 9:1 to 10:1 is worth less than 10 ft/lbs of torque and 10 HP if it doesn't spark knock. So the .3 difference from 9.1 to 9.4 would be less than 3 HP difference. Its not that critical. If you happen to pull those Vortec heads off which you are no where close to needing to do, I would put some Felpro 1094 .016" compressed rubber embossed steel shim head gaskets on it. Those will put you up around 9.6:1.

The Hotcam in your current setup will make a big difference in HP. You could also go with the GM 846 aka Crane 109831 cam. 222/230 @ .050 roller with .509/.528" lift on a 112* LSA. Makes power from ~2,000 to 6,200 rpm. If that is too much for your tuner, you could also go with the GM 845 aka Crane 109821. It is 214/222 @ .050, .488/.509" on a 112* LSA.

gregl316

iTrader: (1)

So a thinner head gasket and a better cam? What about the injecters and fuel pressure?

Or are you saying just a hotter cam? Leave the heads alone?

That sounds more like it. I'm not talking 500rwhp just a mild 300 to 350.

thomas1976

Is this a typo or do these blocks have extra low decks?

Fast355

iTrader: (2)

It was a typo, should have read .025" or there abouts.

gregl316

iTrader: (1)

Now that we have that all hammered out I'll be ok with just a cam. No new intake? What about injectors?

I rode in my friends 5th gen and it is fast. I want mine at least close. At 250hp they leave me in their dust. I want 350rwhp. Can I do it with just bolt on parts? IE... a cam, heads and intake. I know I can do more but my engine is new and I hate to replace it.

Fast355

iTrader: (2)

You should be able to make about 300-330 rwhp without changing too much. Best bang for the buck right now would be pull the heads, open up the pushrod holes, install a set of Alex springs and retainers and bolt on a pair of 1.6:1 full roller rockers then convert to the LT4 Hotcam. If you want more put a bottle on it. A 75-100 shot would be easy to accomadate and make even your current engine run much stronger. The L31 is a pretty strong engine. The cammed/head L31 engine in my Express van has seen ~6,500 rpm and has had about 10 bottles sprayed through it with a 150 hp shot and probably 20 on a 100 hp shot. It is still running smooth amd strong with no hints of trouble.

gregl316

iTrader: (1)

Thanks for the info. So why do I need to open the push rod holes? So I'll need new pushrods to rite? What about new head gaskets? Anything special? Should I have the heads ported or anything? How about the injectors and fuel pressure?

gregl316

iTrader: (1)

Wow thanks. I have read this over and over and it is finally making sense.
1. Head work to make it take 1;6 to 1 roller rockers
2. LT4 hot cam any specific grind with the springs that go with
3. roller lifters if I can
4. How about the thin head gasket?
I already have a Hp fuel pump and a 46mm TBI. I am running 68# injectors. How am I going to fuel this.
How do you put N2o on a TBI engine? Is there a plate for under the TBI or do I direct inject it?

Thank You now I just need to figure out what is wrong with it and get it running right again.

gregl316

iTrader: (1)

I picked out this stuff.
http://www.summitracing.com/parts/nal-12480002
http://www.summitracing.com/parts/nal-12371042
I that what your talking about? So do I need to have the heads machined to work?

Fast355

iTrader: (2)

You will need to do some machine work to properly setup that kit. Some Vortec castings need the valve guide boss trimmed to fully install the valve stem seal. To check you can fully install the valve stem seals and measure the clearance between the seal and the LT4 retainers. Once the seal is fully installed you can check your clearance between the retainer and seal to verify you have .525 + .050" or a total of .575" clearance. Some vortec heads will need the pushrod holes drilled out to 1/2" for clearance for the 1.6:1 rockers. Finally some vortec heads need the spring pockets enlarged slightly for the LT4 springs to seat correctly in the pockets.

Finally don't forget you will need the camshaft retainer plate and bolts that sits behind the camshaft timing sprocket as well as a new timing chain. I have had good luck with and recomeend the Cloyes 9-1157.

http://www.summitracing.com/parts/na...8501/overview/

http://www.summitracing.com/parts/CLO-9-1157/

Finally when you go back together with the engine, I like using these head gaskets to give you better quench and more compression.

http://www.autozone.com/gaskets/head...nce/75445_0_0/

The LT4 Hotcam usually drops in 3* advance on a 109* ICL but was designed for use in a 10.8:1 compression engine. With the steel shim style head gasket, stock head, stock piston, stock deck height, etc you come out about 9.5:1 and ~ .041" quench with a pump gas friendly 7.7:1 dynamic compression ratio. I would advance the cam 4* over the drop-in (7* total) and bring it down to a 105* ICL. It will bring the powerband down slightly to better match with the TBI and dual plane while bringing vacuum up a little from the earlier intake closing.

Fast355

iTrader: (2)

Roller lifters are a must with a hydraulic roller cam like the LT4 Hotcam.

You are going to need about 28-30 psi of fuel pressure to fuel this setup and I would recomeend going to route of a VAFPR if you have the EBL. With 14 in/hg of vacuum on the VAFPR your idle fuel pressure will drop about 7-8 psi down from 30 to about 22 with the 68#. I would check into one of the TBI injector guys to flow the injectors. Flow them at 11 psi, at 22 psi and say 33 psi so that you can plot the injector flow along the curve linearly. IIRC you are running the EBL and will need that information to set the Base Pulse Constant table in the ECM code to allow for proper fuel calculations with varying pressure.

If you put N20 on this engine you could use either the NOS kit designed for a TBI engine or convert to a carb intake and use a carb style plate. You will need a little help from the nitrous kit manufacturer due to the fuel pressure you will be running to get the correct fuel pill sizes.

gregl316

iTrader: (1)

Good gosh all I can say is thank you.
I am going to buy the gasket kit too.
I am going to get my basket together and I will post it so you can tell me if I have it all. Oh and don't I already have a Cam Retainer Plate? Do I need to buy another?

gregl316

iTrader: (1)

I just need to get the rest of the gaskets. I need a cam change kit.
http://www.summitracing.com/cart

Fast355

iTrader: (2)

Your engine if its the 330 HP 350 crate will have a flat tappet cam and those do not use a retainer plate. The crank sprocket also has a larger bolt pattern on the flat tappet cam than the roller. If you are getting a new timing gear, you might as well get a single roller chain. They run with less friction, less wear and greater accuracy and strength.

Fast355

iTrader: (2)

Cart is showing up empty for me.

Fast355

iTrader: (2)

So just thought I would post up some of the information I have gathered on the GM 300/330 HP 350 cam and the LT4 Hotcam as the advertised duration numbers for both from GM are bogus compared to the aftermarket. On a degree wheel, I have personally degreed both cams.

The 300 HP 350 crate engine cam

262/272 @ .006
212/222 @ .050
.290/.306" lobe lift (.435/.460" w 1.5 rocker)
109* ICL, 116* ECL
Which calculates 112.5 LSA

The LT4 Hotcam

272/281 @ .006
218/228 @ .050
.328/.328" lobe lift (.525/.525" w 1.6 rocker, .492/.492" w 1.5 rocker)
109* ICL, 115* ECL
Which calculates to 112* LSA

I modeled the engine before and after cam/rocker/head gasket swap using a 650cfm 46mm TBI unit and small tube shorty style header with a decent exhaust. I am showing gains of 73 HP @ 5,500 rpm and 80 HP @ 6,000 rpm with no loss of torque anywhere. With the smallish TBI, dual plane intake, somewhat restrictive exhaust setup, and 4* advanced Hotcam I am modeling a peak to peak HP gain of 59 hp @ 5,000 rpm and a gain of 39 ft/lbs peak to peak. I think that would put a HUGE smile on your face. I also modeled the engine using the crappy flowing hecho en mexico garbage vortecs being made now from what I can only assume are totally worn out casting cores.

gregl316

iTrader: (1)

http://www.summitracing.com/cart http://www.summitracing.com/parts/fel-1094 http://www.summitracing.com/parts/nal-10168501 http://www.summitracing.com/parts/nal-12371042 http://www.summitracing.com/parts/nal-12480002
I am having a hard time finding a gasket kit. But this is it and I am really liking the numbers.
The motor has a name plate on the oil filter housing that says it was made in 1999. I hope it has the good heads but even with the Mexican castings those are impressive.
Could I do better with a different intake and an adaptor plate?

Thanks I am going to get the parts coming.

gregl316

iTrader: (1)

What about just buying alum. heads? I was looking at this combo.

http://www.summitracing.com/parts/sum-cedl404/overview/

Still getting the cam but this is a good price for the heads and intake. or I could but the heads all by them selfs. save on machine work.

I just want to do it rite this time and not half *** it.

Happy Easter

gregl316

iTrader: (1)

Hey man here is my new basket what do you think?
Price Qty Total




Airflow Research (AFR) 0912 - AFR 190cc Vortec Eliminator Street Cylinder Heads


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ARP 134-3701 - ARP High Performance Series Cylinder Head Bolt Kits


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Cloyes Gear 9-1157 - Cloyes Street True Roller Timing Sets


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Fel-Pro 1094 - Fel-Pro Performance Head Gaskets


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Mr. Gasket 136G - Mr. Gasket Intake Gasket Sets


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Chevrolet Performance 10168501 - Chevrolet Performance Camshaft Locking Plates


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Chevrolet Performance 12371042 - Chevrolet Performance Hydraulic Roller Lifters


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Lifters, Hydraulic Roller, Chevy, Set of 16

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Chevrolet Performance 12480002 - Chevrolet Performance LT4 Hot Cam Hydraulic Roller Cam Kits


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Chevrolet Performance 12496822 - Chevrolet Performance Eliminator Vortec Intake Manifolds


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Chevrolet Performance 12550027 - Chevrolet Performance Vortec Intake Manifold Bolts


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Nitrous Express (NX) 20218-10 - Nitrous Express GM TBI Nitrous Systems


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Trans-Dapt Performance Products 2210 - Trans-Dapt Performance Throttle Body to Carbureted Manifold Adapters


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Fast355

iTrader: (2)

So I may be overthinking here, but why pay a preminum for the Vortec stuff if you are changing both the heads and the intake manifold??

I would go with a set of heads drilled with the pre 86 intake pattern and use either of these manifolds if you are staying TBI.

http://www.summitracing.com/parts/ed...make/chevrolet

http://www.summitracing.com/parts/edl-2901/overview/

The dual plane will be a little more streetable and forgiving with the tune than the single plane, especially in cooler weather. The performer RPM is a great manifold.

While I think AFR heads are great, you are really surpassing what a TBI engine with a Hotcam needs to run really well and moving up into 4bbl carb or 4bbl aftermarket TBI kind of power.

That being said I have the ETec170s on my Express van after one of the Hecho en Mexico heads cracked when I lightly overheated the engine after the radiator drain plug broke going down the highway. I drove it for 6 months before discovering the head issue. Pulled the engine, swapped over to the ETecs with a 215/220 @ .050 custom grind comp cam and it runs strong from off-idle through 6,200 rpm.

gregl316

iTrader: (1)

I think I have it.
I'll just stay with what you talked about earler.
Have the heads done to handle the 1:6 rockers &
the Hot Cam and save the money for the next build.
But I think I'll do the NoS just for fun.