Tpi Vs. Gen Iii

[andrewt2]

ok guys, ive been doing searches on the forum trying to read up on both... but i guess what it comes down to is i really need personal opinions.... which do you guys think is better a gen III swap or a tpi swap. i work for a salvage yard and have access to a 5.3L without accesories for under 400 bucks. or access to a 6.0 for 900. glancing through ebay it looks like you can pick up mostly complete tpi kits from anywhere between 250 to 550. and whats the story behind the cold start injector vs. the maf design, is the cold start junk? would i be happier with a 5.3 or 6.0 in the end? also right now i planned on keeping the the turbo 350 trans for a while... by doing this i believe you have to order a special converter for the trans... right? oh well some of you guys out there give me your opinions *Rockcrlin, shifty, hart rod* thanks in advance.

[streetstar]

I think the tpi conversion would make sense if it was cheap and you already had a pretty nice long block built ----- that said

GM had some good reasons to go from the 1st generation small block to the LT, then finally to the LS series, why not take advantage of their research?
a 5.3 is pretty soft on power in stock form, but a 6.0 is not bad -- either one will run well in your lighter, older truck than in a 5500 lb crew cab 4x4, but if the 6.0 is only a few hundred dollars higher, thats cheap horsepower.
but you may be wasting its potential unless you can get the tranny with it too, though

[67_C-30]

As far as HP capability goes (if that's what you're looking for) the Gen III is going to be far superior. If you are wanting a good running daily driver, both will be fine. The long runner design TPI makes a ton of low end torque and great drivebility with higher gears an non OD tranny, but is all out of breath at anything much over 4500 RPM with a stock setup. In fact, the TPI 350 makes much more torque down low than the 5.3 and would "feel" better in everyday normal driving situations. The speed density TPI's make 345 lb ft at 3200 RPM, and the latest rendition of the 5.3 makes 338 lb ft at 4200 RPM. The earlier 5.3's are in the 325 lb ft range at about the same RPM. The torque curve starts much earlier on the TPI engines, and even though they the upper end Camaro/Firebird and Corvette induction system, they work excellent in a truck. That's my only knock on the Gen III's as a truck engine - you have to zing them up to get the power out of them. The 6.0 has plenty of torque, but it also a pig on fuel compared to the other two. It basically boils down to what you're wanting out of the engine. Buying an engine without accessories is often a big headache and expensive as well.

[andrewt2]

thanks for the info. im not to worried about buying the engine without accesories, i have access to all the accesories off the motor. they're just priced seperate because thats how we sell them at the salvage yard, when i put the numbers together im like at about 650 for a complete 5.3, of 1100 for a complete 6.0 all accesories and wiring and computer. the cost involved in the gen III swap is one thing that scares me tho... im looking to build a daily driver style street truck, with noticeable power but not know track truck just something i can cruise the streets in and drive and enjoy my whole focus on the build thus far has been driveability, its got a rebuilt turbo 350 in it and a rebuild 305. would i be better off to just buy a tpi set up for that 305?

[67_C-30]

Obviously, the 305 is not going to have the power of the 350 or the Gen II but I've had a few TPI 305's in Camaros and they are respectable. It would definitely be your most cost effecient route. What kind of heads are running, centerbolt or old style perimeter bolt?

[71swb4x4]

There is a lot of cost in a TPI swap as well. I bought a whole IROC for $400, and that saved me a lot of money. I had everything right there. Of course there were still a lot of things to buy, like a Vehicle Speed Sensor, I put in a rear tank with electric fuel pump, ducting for the air cleaner, chip burn, and I am sure I am missing a bunch of stuff.
With the Ebay "complete" TPI packages you still may be missing sensors and such. Or the computer may not be matched right, etc.

[andrewt2]

Originally Posted by 67_C-30

Obviously, the 305 is not going to have the power of the 350 or the Gen II but I've had a few TPI 305's in Camaros and they are respectable. It would definitely be your most cost effecient route. What kind of heads are running, centerbolt or old style perimeter bolt?

im running the old perimeter bolt style heads,

[andrewt2]

Originally Posted by 71swb4x4

Of course there were still a lot of things to buy, like a Vehicle Speed Sensor, .

where does the vss mount up? is it off the speedo gear?

[Ackattack]

I had a TPI 350 in my 72 GMC. I always read about it's great torque. When I put it in I also swapped in a 700R4. With the stock 3.08 gears it was a big turd on the highway, barely having enough power to make it up small hills without shifting down to third. I swapped in 3.73s and that really was the ideal gearing. I ran a 15.9@89 or so with it at the track. So overall I was disappointed with it. I was able to eak out 18.5mpg though.

In comparison I have a 2005 crew cab 4x4 with the 5.3L in it (5600+ lbs) and it cruises down the highway at about 1600 rpms (about the same as the tpi/700r4/3.08) with no lack of power. I haven't ran it at the track, but it feels pretty strong. Also, on straight highway driving I can easily get 19mpg or better.

I would definatly go with the genIII over the TPI. The 6.0 would be nice if you can swing the extra cash, but the 5.3L is still a better choice.

[67_C-30]

Originally Posted by Ackattack

I had a TPI 350 in my 72 GMC. I always read about it's great torque. When I put it in I also swapped in a 700R4. With the stock 3.08 gears it was a big turd on the highway, barely having enough power to make it up small hills without shifting down to third. I swapped in 3.73s and that really was the ideal gearing. I ran a 15.9@89 or so with it at the track. So overall I was disappointed with it. I was able to eak out 18.5mpg though.

In comparison I have a 2005 crew cab 4x4 with the 5.3L in it (5600+ lbs) and it cruises down the highway at about 1600 rpms (about the same as the tpi/700r4/3.08) with no lack of power. I haven't ran it at the track, but it feels pretty strong. Also, on straight highway driving I can easily get 19mpg or better.

I would definatly go with the genIII over the TPI. The 6.0 would be nice if you can swing the extra cash, but the 5.3L is still a better choice.

Your '05 crewcab has at least 3.42 gears but they are probably 3.73's. That's what's in my 2000 Z71. A .70 : 1 OD with 3.08's is a turd with ANY engine. That equates to 2.156 final drive gear ratio. Your crewcab in stock trim is a mid 17 second performer in stock trim. The 403 HP 6.2 GMC Denali crew cab only runs 15.5 @ 92. 15.9 is very respectable for a stock TPI 350 in a brick, so I don't really understand the disappointment. Its a 245 HP engine at its best in stock form.

[67_C-30]

Originally Posted by andrewt2

im running the old perimeter bolt style heads,

You will be better off with a 85 or 86 TPI base so you won't have to slot the inside intake bolts. You can bypass the cold start injector if you swap to speed density set-up. You will need a 7730 computer and it would work better with a custom burned chip which is not real expensive.

[Andy4639]

I have a 1986 TPI motor in my 71 with street & performance wiring and chip. The motor has 250,000 miles on it. I'm running 4:10 rear gears with a 700-R4 and at 70 MPH I'm running 2500-2700 RPM'S. I have plenty of torque and it will run all day at 70-80 MPH out on the interstate. I get 18MPG when out on the road. I'm very pleased with it. Save your self a big headache and just buy a wiring harness.
These engines aren't built to drag race and they want tear up a track in stock form but they will run well and give you good gas milage with the right combo. I disconnected the cold start injectors and never had a problem with it cranking in the cold here in SC. I have the map senor and it's never failed since I installed it in 1987 into the truck.

[71swb4x4]

The VSS on mine did run off the speedo gear. I had an '86, so it may have been an early year thing. I bought my VSS and some of my air ducting at jagsthatrun.com

[Ackattack]

Originally Posted by 67_C-30

Your '05 crewcab has at least 3.42 gears but they are probably 3.73's. That's what's in my 2000 Z71. A .70 : 1 OD with 3.08's is a turd with ANY engine. That equates to 2.156 final drive gear ratio. Your crewcab in stock trim is a mid 17 second performer in stock trim. The 403 HP 6.2 GMC Denali crew cab only runs 15.5 @ 92. 15.9 is very respectable for a stock TPI 350 in a brick, so I don't really understand the disappointment. Its a 245 HP engine at its best in stock form.

yeah my CC has 3.42 gears, but it also has 32" tires while the 72 only had 27" tires.

Also, my tpi had headers, cold air intake, adjustable fuel pressure regulator, and an airfoil thingy.

Oh, if you do go with a TPI, I'd get an 87 and up. They're roller cams. I'd also stay away from the later speed density models if you plan on doing modifications.

Its just for the money and hassle associated with either engine, I think most would be happier with a genIII engine.

[red71cheyenne]

I wish I could get 18 mpg out of mine. I really like it and the 700R4, but its not been a real sweet deal after that. I think I spent about $1600 getting all the parts together and installing. Don't get me wrong, it runs like a striped ass ape, but it didn't make a difference on my gas mileage. I get the same thing I got with the Quadrajunk and TH350. 3.73 rear end and 31X10.5 tires. It does look cool as H*ll though

[Andy4639]

I have the factory ram horns and a cold air box with K&N filter. 2 1/2" pipes. Nothing fancy the motor is stock. I did do the corvette upgrades to the 700-R4 though. I run unleaded in it and a can of injector cleaner every now and then. I did have the injectors cleaned and balanced when I built the engine.

Cold air box is a 90 caddy seville box modified to a couple of 4" pipe fittings with a 4" hole cut where the regulator was mounted. A 4" 90 into the bottom of the box.

[red71cheyenne]

Originally Posted by Andy4639

I have the factory ram horns and a cold air box with K&N filter. 2 1/2" pipes. Nothing fancy the motor is stock. I did do the corvette upgrades to the 700-R4 though. I run unleaded in it and a can of injector cleaner every now and then. I did have the injectors cleaned and balanced when I built the engine.

Cold air box is a 90 caddy seville box modified to a couple of 4" pipe fittings with a 4" hole cut where the regulator was mounted. A 4" 90 into the bottom of the box.

I like it! The Orange really sets it off. Mine isn't polished or color matched or anything, just the brushed aluminum look with a K&N on the intake. I am running Dynomax coated headers into 2 and 1/4s all the way out the back. Here's a pic, the fan is gone now though, upgraded to dual electric fans!!

[billydonn]

Originally Posted by 67_C-30

As far as HP capability goes (if that's what you're looking for) the Gen III is going to be far superior. If you are wanting a good running daily driver, both will be fine. The long runner design TPI makes a ton of low end torque and great drivebility with higher gears an non OD tranny, but is all out of breath at anything much over 4500 RPM with a stock setup. In fact, the TPI 350 makes much more torque down low than the 5.3 and would "feel" better in everyday normal driving situations. The speed density TPI's make 345 lb ft at 3200 RPM, and the latest rendition of the 5.3 makes 338 lb ft at 4200 RPM. The earlier 5.3's are in the 325 lb ft range at about the same RPM. The torque curve starts much earlier on the TPI engines, and even though they the upper end Camaro/Firebird and Corvette induction system, they work excellent in a truck. That's my only knock on the Gen III's as a truck engine - you have to zing them up to get the power out of them. The 6.0 has plenty of torque, but it also a pig on fuel compared to the other two. It basically boils down to what you're wanting out of the engine. Buying an engine without accessories is often a big headache and expensive as well.

That sounds about right... pics and video of my TPI truck are below.

[billydonn]

Originally Posted by 67_C-30

You will be better off with a 85 or 86 TPI base so you won't have to slot the inside intake bolts. You can bypass the cold start injector if you swap to speed density set-up. You will need a 7730 computer and it would work better with a custom burned chip which is not real expensive.

That sounds about right... also a corvette base of any year will avoid the bolthole problems. Ford Motorsports 24 lb injectors for the TPI are the in thing nowadays too!