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Old 08-25-2011, 12:28 AM
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350 Vortec TPI Build: Need some help/advice/suggestions

So its time for the Camaro to depart with its original 3.1L V6 and grow some balls, so by the end of this week, the V6 will be sitting on the ground, and I'm going to start building my 350.

I'm packing some goodies in the new 350 while I'm in there, and I have a few questions, pretty much all valvetrain stuff though. So heres what I got so far:

86-94 350 Longblock
906 L31 Vortec Heads
SDPC Vortec Intake baseplate
Stock runners
Stock Plenum
Stock throttle body
24 ilb LT1 injectors
3" Headers and 3" Flowmaster American Thunder exhaust
700R4 out of a 87 IROC-Z w/120K
'165 ECM, still looking for a prom

I want to do even more to it to get this to run even better, and more powerful. I want to get a .525/.525 LT4 Hotcam and 1.6 full roller rockers to make the most out of the Vortecs and the TPI. But before I go too far I should probably let you all know what my goals are.

I want to make at least 1HP per cubic inch, and I'm hoping to hit 375HP at the crank to translate into 300 at the wheels, and if I'm making that much power, it will probably translate into 425 ft/ilbs or so I'm guessing. I know that I will have an engine with tons of low end torque thanks to the TPI intake, and I know that the engine will run better at higher RPMs thanks to the Vortec heads. I want to run higher lift than the 191/196 and 202/207 Cams that I have, and the LT4 hotcam is a mean cam, but I'm also thinking about a ZZ4 cam, because it will still provide .475 lift on the intake, and .510 on the exhaust to help the poor flowing exhaust characteristics of the 906 Vortec heads.

But for me to do anything more than .480 lift, I need to modify my Vortecs to accept more lift, and I'm not sure how to go about that. And, I have questions about going all roller for my engine. When I tore apart the 350, I knew it was a truck engine because it was a flat tappet cam and lifters, not hydraulic roller like any post-87 Camaro/Corvette engine should be. What all is involved with turning a flat tappet engine into a full roller engine with roller chain which I have, roller lifters which I have, and the roller rockers that I want to run?

Also I plan on using Felpro-1094 head gaskets 4.1" diameter and .015" compressed thickness, that on a 350 and the Vortecs 64cc combustion chambers will net me 9.7:1 compression like a stock L98, and will make more power than what the 906's normally run on an L31 at 9:1.

I'm also wondering what my timing should be. I've heard of 350 Vortec TPIs before running 32-34 degrees of advance, but is that too much for a street car?

The county I live in does not require emissions for state inspection, so I'm not going to run any. EGR delete and no AIR system on the headers should net me a few horsepower not running all of that and a smog pump on the engine. Yes, the engine will run hotter, but it will have more power and I can easily install a cooler thermostat to keep the engine cooler.

So what should I do for a cam, and if I do go higher than .480 lift, what should I do to make it work(rockers/valve springs, etc.)

Any and all help/ideas appreciated guys!

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Old 08-25-2011, 08:04 AM
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I won`t comment on the build but I will say by all means install V8 Coil springs under the front end, you won`t regret it any.
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Old 08-25-2011, 09:08 AM
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I did a L31/TPI 355 with the LT4 hotcam kit. Strong low rpm and mid rpm torque. Have spun the engine to 7200rpm, but not making power up there.

You arent going to make much power with the stock plenums and runners.

SDPC made 367 hp/406 lb/ft on their SDPC TPI.L31 crate engines.

The ZZ4 cam will get you nowhere near your goals with 208/221 duration.

To run over .480" lift on stock L31 heads will require 787-16 Comp Cams retainers and any Beehiove spring, 26915/26918, PAC beehives or 02-04 LS6 behives.

Stock the TPI 305 ran 15.5@88mph, TPI/L31 355 ran 13.8@99mph on stock 85chip and 32 lb/hr injectors.

Stock an L31 is rated at 255 sae net hp@ 4600rpm, and 330 sae net lb/ft torque at 2800rpm. That is roughly 310-320hp gross hp.

If I did it again, it would be getting an LS1 or a brand new LS6 for $3200.

peace
Hog

Last edited by Hogg; 08-25-2011 at 09:24 AM.
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Old 08-25-2011, 12:45 PM
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What compression did you run on your engine? And thanks for the retainers and spring info, thats what I was wondering about.

Why didn't you tune the 85 ECM for the mods you made? I bet it would have run a lot better in the 1/4 mile.
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Old 08-25-2011, 02:43 PM
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Think you are way off in your torque expectations. Are you using the MAP or MAF system? If you are using MAP, then you can not use a very radical cam with out a bunch of reprograming of the computer and even then not sure how good that would work. Also, you may have to go to 30# injectors to approach your target HP, another reprogam. On the up side, you can get a nice running motor with pretty good fuel economy.

Trees
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Old 08-25-2011, 03:52 PM
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Im using MAF for that reason. The 3.1L V6 that my Camaro came with was MAP, and you could have so many MAP problems and go through hell and back to find out why the car is studdering to find out that your MAP like problem was one of the many other sensors that MAP is dependent on! Im so sick of MAP, and MAF is easy to tune, and its only one sensor, not multiple ones.

I found a build online that made 357hp at 4900 rpm with the LT4 hotcam and 24 ilb injectors, and SDPC said that they made up to 375, but didn't say what injectors they used. My torque will be close to 400 ft/ilbs or at least somewhere in that neighborhood.

I'm going to eventually have to get high-flow runners if I want to improve this setup even more.
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Old 08-26-2011, 11:12 AM
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Quote:
Originally Posted by 90CamaroRS
What compression did you run on your engine? And thanks for the retainers and spring info, thats what I was wondering about.

Why didn't you tune the 85 ECM for the mods you made? I bet it would have run a lot better in the 1/4 mile.
Stock 9.4:1 plus whatever the 0.030" Overbore added.

If it were my car I would have tuned the ECM. ACtually if it were my car I'd stuff a 411 OBD2 PCM in it and tune it with Tunercat OBD2 that I use on my 97 L31 truck.
I tell him to spend the $160 for a chip from Fastchip, but he wont spring for it. He wants to get a local dyno tune, but the guy will only tune it if he switches it to Speed density. b/s
The car has a decently lopey idle esp. when warmed up, but hunts for idle excessivley at idle in gear, and will stall in gear A/C on at stoplights. This all in the tuning, less MAP pressure due to cam and the ECM is confused.

The Iroc netted 1.80 60ft times with thestock 305 TPI TC and stock 3.42 gears. The car will almost dead hook with a WOT stomp from idle. Its a good all around combo, good low rpm torque, and decent 3rd gear pull.
Even with the stock 305, thecar did easy OD burnouts with the 245/50-16's.

He swapped out the stock 85 MAF from Granatelli and he says it ran a 12.8, but I havent seen the slip, so I am skeptical.

That lower intake is $400US and the one I installed was one of the1st ones released and it took over 4 hours of mods to get it to work. Bolt holes drilled by not tapped, alignment issues. I have heard they are better now.

I would think that 400 lb ft is attainable.

A Ramjet 350 intake will work.
I like this intake as well, under $200.

http://store.edelbrock.com/mercuryme...ensorslot.aspx
pic here of the marine intake I am using in my 97 L31 truck



Here is a stock L31 Vortec 350 intake next to a marine intake


peace
Hog
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Old 08-26-2011, 06:41 PM
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Quote:
Originally Posted by 90CamaroRS
So its time for the Camaro to depart with its original 3.1L V6 and grow some balls, so by the end of this week, the V6 will be sitting on the ground, and I'm going to start building my 350.

I'm packing some goodies in the new 350 while I'm in there, and I have a few questions, pretty much all valvetrain stuff though. So heres what I got so far:

86-94 350 Longblock
906 L31 Vortec Heads
SDPC Vortec Intake baseplate
Stock runners
Stock Plenum
Stock throttle body
24 ilb LT1 injectors
3" Headers and 3" Flowmaster American Thunder exhaust
700R4 out of a 87 IROC-Z w/120K
'165 ECM, still looking for a prom

I want to do even more to it to get this to run even better, and more powerful. I want to get a .525/.525 LT4 Hotcam and 1.6 full roller rockers to make the most out of the Vortecs and the TPI. But before I go too far I should probably let you all know what my goals are.

I want to make at least 1HP per cubic inch, and I'm hoping to hit 375HP at the crank to translate into 300 at the wheels, and if I'm making that much power, it will probably translate into 425 ft/ilbs or so I'm guessing. I know that I will have an engine with tons of low end torque thanks to the TPI intake, and I know that the engine will run better at higher RPMs thanks to the Vortec heads. I want to run higher lift than the 191/196 and 202/207 Cams that I have, and the LT4 hotcam is a mean cam, but I'm also thinking about a ZZ4 cam, because it will still provide .475 lift on the intake, and .510 on the exhaust to help the poor flowing exhaust characteristics of the 906 Vortec heads.
The LT4 hotcam is an older grind that works good, but there are better cams out there for you. Try the "Comp 503", specs are 224/230, .503"/.510" (w- 1.5 rockers) on a 112 LSA. That is about as hot as i'd go with a TPI car. The intake tract simply poops out at around 5500rpm. No sense in picking a cam that wants to rev higher than that.

Quote:
Originally Posted by 90CamaroRS
But for me to do anything more than .480 lift, I need to modify my Vortecs to accept more lift, and I'm not sure how to go about that. And, I have questions about going all roller for my engine. When I tore apart the 350, I knew it was a truck engine because it was a flat tappet cam and lifters, not hydraulic roller like any post-87 Camaro/Corvette engine should be. What all is involved with turning a flat tappet engine into a full roller engine with roller chain which I have, roller lifters which I have, and the roller rockers that I want to run?
The easiest way is to start with a roller block, lol. They are very plentiful. If you still want to use the block you have, you will need a thrust button for the camshaft and then you'll need tall roller lifters that have a linkbar. Lifters of that type can run from $450-$1000. With a factory roller block you can use the dogbones and spider assembly, which is much cheaper.


Quote:
Originally Posted by 90CamaroRS
Also I plan on using Felpro-1094 head gaskets 4.1" diameter and .015" compressed thickness, that on a 350 and the Vortecs 64cc combustion chambers will net me 9.7:1 compression like a stock L98, and will make more power than what the 906's normally run on an L31 at 9:1.

I'm also wondering what my timing should be. I've heard of 350 Vortec TPIs before running 32-34 degrees of advance, but is that too much for a street car?
Nobody will be able to tell you exactly what timing your motor will want. You will have to pick a baseline and go from there. Too many variables not to mention the altitude you live at can effect it.

Quote:
Originally Posted by 90CamaroRS
The county I live in does not require emissions for state inspection, so I'm not going to run any. EGR delete and no AIR system on the headers should net me a few horsepower not running all of that and a smog pump on the engine. Yes, the engine will run hotter, but it will have more power and I can easily install a cooler thermostat to keep the engine cooler.
Why would it run hotter? If the cooling system is working properly there should be no change.

Quote:
Originally Posted by 90CamaroRS
So what should I do for a cam, and if I do go higher than .480 lift, what should I do to make it work(rockers/valve springs, etc.)

Any and all help/ideas appreciated guys!
Comp 918 beehives are a good choice, just make sure to install them at the proper height. Most people just bolt them on and go, big mistake. Buy yourself a vlave spring height checker tool. They are $10-$15. If you find that the springs are not high enough, then you can order special locks the raise the retainer up a little. If they are too low you can shim them. They need to be at the correct height to do their job. If you do indeed need to raise them up with special locks, you will have to run non self-aligning rockers.
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Old 08-26-2011, 09:43 PM
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