I was just curious, is an LT1 engine a big advancement over a TPI engine given they are both relatively stock? And which one is more expensive to modify?

 

Well I am only a novice when it comes to engine swaps and components. But I have learned a few things by reading the boards. The TPI system looses power @ 5200 rpm. This is why some guys swap to an LT1 intake. Also you will see a lot of guys going with an LT1 cam in their third gen.

So that will be two reasons why the LT1 would be a better choice.

Bill

 

what kind of parts and work is needed to convert to an LT1 intake and can you still use the stock sensors and computer?

 

The LT1 intake has no provision for a distributor, as a TPI or TBI or a carbed motor usually requires. Some degree of modifictaion is definitely required.

IMHO the LT1 is what GM should have used instead of TPI starting in about 87. It's so much simpler and works so much better. But don't get me started, yet another "why TPI sucks" vs "why TPI is almost barely competent sometimes in some situations if you spend enough money and don't expect too much" flame war will get started by TPI people that like what they've got. And truth to tell, if you're willing to give up 100 HP or so, compared to what the rest of your motor is mechanically and fluidically capable of, TPI is perfectly fine.

The TPIS MiniRam is virtually identical to the LT1 intake (or rather the other way around, since the LT1 intake was "invented" several years later than the MR), and gives similar flow and HP characteristics.

 

Wrong ppl.

You can actually put a carb and carb intake with a regular, old style distributor. They made it posible if you know your LT1's.

RPMs as far as I know are not a factor in LT1's. As long as you get good aftermarket parts for a gen1 engine you won't have a rev problem.

If you want to put an LT1 into your 3rd gen camaro (something I am working on right now, I am still buying engine parts and my second Iroc-z for the build), you will need all new wiring which you can get from painless and some other places (there are some other people on the board who told me about another place to buy the wiring for it) and you do need a new computer and you will probably have to disable the passkey2 system (I am going to look into if there is actually any way to have it legitly installed in the car for vehicle anti-theft protection).

The differences that I can remember between teh LT1 (gen2) and TPI (gen1) is the reverse cooling which means the compression ratio can be higher without pinging so you get more power just from that. Stock intake manafold is one piece. Head bolts are at different angles. Most of the parts are not interchangable from an LT1 to a TPI system. I know Chevy rated teh LT1 over the TPI version as being 20% more powerful and more efficient, but I think that's overall, not in each category. That's stock against stock though. Given the right aftermarket parts they could probably run neck and neck. Also the zz4 is a gen 1 motor and comes with a higher stock performance than an LT1. A zz4, if you really don't want to do all the woring about electrical and stuff, could be a better way to go about it. You should try and find more information on the internet about all those engines.

 

Right, you can get an intake from GM that fits on the LT1 and mounts a carb; but that's not at all the same thing as a "LT1 intake". The "LT1 intake" is a small thing, sits low between the valve covers; has very short runners, almost a direct shot from the plenum to the head port; and of course it uses port fuel injection. It uses a horizonal-draft throttle body mounted on the front of its plenum, like most FI cars do.

Head bolts are at the same angle.... perpendicular to the block.

The LT1 also has the OptiSpark ignition system which mounts on the front of the motor between the water pump and the timing cover, and is driven directly by the cam; and the water pump is also driven by the cam, via an intermediate shaft and gear arrangement. It has no distributor in the traditional place, but instead, it has a dummy housing and a shaft, to drive the oil pump and seal up the lifter feed oil passage that goes right through the middle of the dist body.

But, the reason people would want to swap that intake onto some other motor, is because its short runners are much less restrictive than the long ones on TPI. It's difficult to get a TPI motor to equal even a very lightly modded LT1; and if the LT1 gets a better exhaust and cam, it's nearly impossible. The LT1 intake design has far more potential as a "performance" setup than TPI does. Even in stock trim, the LT1 motor produced about 15-20% more horsepower than the older TPI motors did.

 

yea well go read up on LT1's because the intake and head bolts are at 73degrees.

The reason I said something about putting on a carb is because you didn't say it could be done when it can.

With the right setup, the power would almost be even. The Stock TPI came with cast iron pistons while the LT1 had hyperuetic aluminum pistons. The LT1 had a lower LSA and more duration plus higher lift for intake and exhaust. If you go with the right aftermarket stuff you can get them to run neck and neck. For me, I like the new features for the LT1. Actuallly the only reason I am building one is I saw a shortblock LT1 being sold cheap and couldn't help myself. Now I am still buying all the parts. I have like 6 books to help em and I have to do it in 2 1/2 months because I am going into the air force.

 

That's the intake bolts at 72°, not the head bolts. The head bolts are perpendicular to the block deck in both motors. That's not exactly something that I have to "read up on" at this point. When you've built a few motors, you'll also discover that there's alot of things you get real familiar with from experience.

No car motor that I know of has come with cast iron pistons for a hundred years. TPI motors came with cast aluminum alloy pistons. In any case, the metallurgy of the pistons has very little effect on the power output (except that cast iron ones would be so heavy and prone to breakage that it would be impossible to get any modern amount of power out of such an engine).

The thing that determines TPI's power characteristics in particular, is the acoustic tuning of the runners, which is specifically desisnged to produce a torque peak at around 3600 RPM, at the expense of any torque at more than about 4500 RPM. The LT1 uses no such tuning, and as a result doesn't have the boost in low-midrange torque, but also doesn't have the high-RPM liability. The cams aren't all that much different between the 2 motors; they certainly aren't where any power differences lie. In fact, some of the LT1 cams are less aggressive than the L98 cams. Right, except that, that basically means all the right aftermarket stuff for the TPI ($$$$) vs a stock or lightly modded LT1 (not so much $$). Bottom line is, there's no way to get a TPI motor to keep up with a LT1, unless you run a modded TPI against a stock LT1. That of course can be done, and you can of course make the TPI car faster if you allow it to be hopped up but handicap the LT1 in some way. Sink equal $$$ or equal effort or equal parts (cam, heads, exhaust) into each motor, the LT1 will walk all over the TPI, every time, no questions asked, no possibity for any other outcome, period.

You really should get your technical facts straight. Posting a bunch of garbled and mangled and confused stuff doesn't help anybody.

 

LT1's get so much better mpg, even when modded. That is one of the best benefits of the LT1.
My main gripe with the LT1's are the waterpump drive shaft seal in the timing cover. I tore 4 of them and said **** it, I am going electric.
Another is the opti-spark, but they have been coming down in price lately, I think $139 for a complete new one from Autozone.

I was a huge fan of TPI when I had my carb, but then I got the TPI and it wasn't all that great, looked cool as hell, but couldn't breath.
StealthRam is going onto the Formula next year. Gonna have it sit on a sbc400.

An LT1 in a 4th gen costs more to modify than an LT1 in a 3rd gen.
It's mainly the exhaust systems that costs more.

Oh, and they seem to hold up great with tons of miles on them.
My old 96 Trans Am 6 speed (now my brothers) ran a best of 13.4@105 with a 150K on it with bolt ons and street tires.

He put heads and cam with stock tune and nittos and ran a 13.22@107 with traction problems and 162K miles on it.

 

One of my buddies with a 97 WS6 vert just got his heads/cam LT1 tuned the other day. 452HP at the wheels with a stock bottom end.
That is approx. 531hp at the flywheel which is a 226hp increase over stock. Car still gets 25+mpg.
I don't know any high HP TPI that gets that kind of milage. So, in the long run, the LT1 will be cheaper due to the cost of the gas.

 

and the computer isn't setting off any codes? What duration/LSA is he using? How much did it cost him for the full port and did he do it to just the heads or the intake manafold too?

 

Computer is cool, no codes.
cam is a custom gound cam, don't know the specs since it is a secret, heads are AFR 195 (?) LT4 with an LT4 intake.

 

if it's LT4 it's going to have at least 240cfm flow rates. Secret cam huh ?

 

oh, lol. 195cc

 

I know the heads are ported LT4's, but I can't recall if the numbers are AFR 194 or 195, I am having a brain fart.
Cam was designed by Joe Overton who has the worlds fastest N/A LT1 4th gen.