thegmguy

Hey guys! Been lurking on this forum for a few years soaking in all the TPI knowledge I can. The time has come to ask a few questions. Here's my scenario: I have a 97 GMC K3500 crew cab long box. Originally came equipped with an L29 454. Stock trim makes 290 HP and 440 ft/lbs. Worked fine but left lots to be desired. Spun a rod a year ago, and there it has sat. My original plan was to rebuild the L29 with a few goodies...502 H.O. cam, headers, exhaust, 36lb injectors from an L67, 0411 pcm/24x conversion with coil near plug. Hoping this would get me up over the 500 ft lb mark.

My problem is my fascination with TPI. I love the torque they can make, and have been curious if a small block would be up to the task of pushing my big rig down the road and occasionally pulling a 20' car trailer. I have a 638 roller block, set of Eagle forged I-beam rods, and .030" hypereutectic pistons for a 383. I also have a stock tpi setup from an 89 T/A.

I know stock TPI falls on its face after about 4500, which, for many of you guys trying to run fast at the track, stinks. But for a guy like me, I rarely spin the truck up high. I have a set of vortec 906 castings set up to run .500 that I thought would work well, but that Scoggin Dickey/Edelbrock manifold is a pricey piece. Maybe it's still the way to go. If there was another inexpensive head out there that would help me get to my 500+ ft/lb goal and allow me to use a stock style lower (even ifvthat was a Corvette lower since it retained the traditional SBC intake pattern) I'd be ecstatic. Any suggestions? I'd like to keep compression under 10:1. The pistons are 12cc dish.

Next question is what cam would you recommend? Hydraulic roller is a must, but low end grunt us what I'm after.

Back to heads/intake...obviously the long runners of a stock style tpi are what contribute to great torque. A TPIS unit or similar is currently out of the question for me because of price, so I'd like to see what stock runners/plenum do (ported is ok). My other question though is if a Holley Stealth Ram will truly kill the bottom end torque like I have been reading. I found a HSR knockoff that can be drilled for vortec heads for $300, but I don't want to do it if it moves power too high in the rpm range.

I'm sure I'm forgetting something, but I'd love to have you guys' input/suggestions.

Orr89RocZ

iTrader: (20)

Skip the vortec and stock tpi idea. You need airflow. Set of 180 cc heads like afr, profiler/jegs, etc. FIRST tpi or all aftermarket with a large tube runner like as&m, tpis bigmouth etc. that should get you near 500 lb ft

thegmguy

I understand that I can reach my 500+ ft/lb goal with expensive aftermarket stuff...I'm just trying to stay on a budget to see if I can get it to work. Otherwise I'll just build the big block. If I can do the 383 for close to what the 454 would cost I'd love to do it, just so I can say I have a small block in a big truck that actually performs.

Vortec heads have a 170 intake, so I don't know that $1000+ for heads is worth the little extra. From my understanding not going too big on port size will keep power lower in the rpm range. Is that correct?

Street Lethal

iTrader: (16)

You would need to port out the TPI substantially like I did, and to be honest, it really is a waste of time, and I don't see myself doing it again anytime soon. You can always go the ebay route if your looking for cheap aluminum heads and HSR setup, but remember, you get what you pay for in the end...

thegmguy

What kind of numbers did yours put down with stock ported setup? What heads and cam?

Orr89RocZ

iTrader: (20)

In short yes. But you are trying to make alot of torque at a relatively low rpm on a decent cube size motor. That all equals airflow. Vortecs ported abit will help, i'd say 250 cfm is a good target to achieve. Thats 20 cfm more than stock, the aftermarket ones in that 180 range tend to flow in that area 250-260 depending on valve.

If you ported stock base to the max, cleaned up vortecs with 2.02" valve flowing 250's, you'll still need an aftermarket big tube runner to support them.

Keep comp low for towing stress which further decreases power potential. Tpi can make some torque just gotta feed the airflow needs, which stock stuff cant really do

thegmguy

Hmm...ok, so do you think stock vortecs would be essentially choking the 383? Is the stock TPI setup (say with the Edelbrock Hi Flow base) going to be the choking point for the heads?

I guess my thought is if it can come close to doing what I want it to do in relatively stock form (vortecs with decent springs, good cam, stockish TPI with Vortec base, etc), then I can justify putting a little more money into it to perhaps make it run a little more like it could/should (ie better flowing intake/runners). I just don't want to put a ton of money in this thing to find out it's actually not quite going to do what I want it to do. If that makes any sense.

If the stock TPI setup is going to be what chokes the heads, is, say, one of those knock off HSR setups going to be better? I don't want to sacrifice flow for low end torque if that's going to be the problem, but if it gets me more what I'm after, I'm ok with that. They are inexpensive.

Street Lethal

iTrader: (16)

My 305 w/siamesed TPI setup makes about 400-rwhp at 6 pounds of boost pressure. This is with stock ported heads, and pretty big Lunati cam. Naturally aspirated she should be somewhere between 275- 300 rwhp, static compression is a tad under 9.1:0 as well...

Orr89RocZ

iTrader: (20)

You will have a hard time getting the torque you want in an hsr without turning alot of rpm. Figuring 500 lbft at crank is over 400wtq thru an auto. My 383 hsr made 400whp/380wtq. Peak torque was 4500 rpm and held flat between 4-5k rpm basically. Hp at 6300-6600. Not a truck pull motor

thegmguy

Street Lethal, those are impressive numbers for a 305.

I kinda suspected that the HSR was more of a high rpm setup. So, if I want to use Vortec heads (sounds like they're capable of my goals with some work), what're my options for traditional style TPI setups that'll bolt to the Vortec heads? Sounds like stock runners/plenum and the Edelbrock base are going to need a lot of work. What else is out there?

Orr89RocZ

iTrader: (20)

Thats it. Vortec heads you are stuck with the vortec tpi intake which really needs work to shine. There was talks of first tpi being made with a vortec pattern but not sure

thegmguy

Well dayum...that's not what I wanted to hear haha. With a traditional style head (intake bolt pattern that is), who else builds a high-flow traditional style TPI besides TPiS (actually looks like the Big Mouth isn't available anymore) and First?

Orr89RocZ

iTrader: (20)

Thats it for regular bolt pattern. Edelbrock which tpis used to use and apply a port job to, or first tpi which is probably best deal going

Fast355

iTrader: (2)

I would stick with a big block in a big truck like that. I have a built up 5.7 in my Express and I am still considering finding and buying an 8100 for it. An 8100 with a mild cam, tune, headers, and a decent intake setup will make over 500 ft/lbs of torque and over 400 hp. There are 8100/4L80E tunes that were used in the Express and 2500 Suburbans. If you pickup an Express 8100 it will have the correct brackets to install your existing accessories and be a fairly straight forward swap. The 8100 makes 300 ft/lbs of torque at idle speed in stock form and 355 lb/ft @ 850 rpm. It is also factory coil per cylinder.