OK, I've been digging around the net all day trying to figure some of this stuff out. My 2 basic questions come down to:
1. What is the difference between the LT1 design and the TPI 350?
and
2. What differences are there between the Corvette LT1 and the Buick Roadmaster LT1?

What do I know so far? not much.

#1. The LT1 uses a reverse-flow cooling system that allows the engine to operate at a more optimum cylinder temp. The LT1 uses "optispark" whereas the TPI uses an old-style distributor(?). The LT1 needs to be moved over 2" in the engine compartment- why? Other than that I'm unsure of anything else for #1.

#2. The 'vette was built with aluminum heads, whereas the Buck Roady was built with cast iron heads. I also know the 'vette LT1 was rated with a higher HP (unsure of TQ ratings). That's it for my knowledge of #2.

It's going to work out like this... I can get an awesome deal on an LT1 with 12k miles on it from a Buick Roady ($200 running with stand). I'd like to do a basic rebuild (maybe more?) and use an Archie kit to drop it in. Should I spend the extra cash (typically $300-500) to get a set of Aluminum LT1 heads? Or should I wait and do that later? I'm not going to do anything drastic to the car to begin with (I need it drivable while I'm saving cash), but in the long run I might be investing in a NitrousNX kit as well as some other performance stuff for it .

And a question directed primarily at Archie. I recently installed a 440T4 OD tranny- which I'd still like to keep. I know that Pat Ciarcia was able to build up a T125 stock tranny to sustain his 10sec Fiero. Do you have any info on what was actually done? Also, have you been in contact with him recently? I understand that others have tried to contact him without any luck (I just sent an emial now). Now I'm not looking to make or beat his 10 second runs (the car will still be a regular driver)- I just don't want to fry my tranny the first month of driving

Thanks to all in advance for your knowledge and resources!

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As the Proud new owner of a LT1 Caprice ..let me help out.

Vette LT1 4 bolt main block aluminum head
300hp

Caprice 9C1 , roadmonster , Impala SS 2 bolt main iron head. Impala SS has electric fans Caprice and roadmonster have clutch driven fans 260hp

Camaro: 2 bolt main blocks , aluminum heads 275-285 Hp.

These are just basic differeces. The nice thing is that you can get LT4 heads and put them on any of these LT1 series motors.

They all have reverse flow cooling. Keep in mind Roadmaster and Caprice ECm's are limited to 108mph. Impala SS's are not limited. Also keep in mind the chips are HARd wired , no swapping , need a power programmer.

Even if you have a Iron head Lt1 you will have no problem laying down serious ass whoopings. Getting a caprice with the LT1 into the 14's is like shooting fish in a barrel.

as for the TPI , or L98 motor. It's a low end Tq motor , great for autocross , in stock form power falls off at about 4800rpm. But Tons of Torque , more so than an LT1 in the lower RPM range.

I say wait and get the heads later. The motor is a beast , nice powerband. I love the TPi and we have an 87 Vette used for autocrossing , but I still reccomend getting the LT1. Newer design , better platform for cheap power. There is a huge aftermarket for the LT1.

The LT1 has to be moved over in a Fiero because of the drive belt setup I believe.
There is a site ont he net devoted to a Lt1 Fiero.

Jonathan McCreery
1994 Caprice wagon
LT1 ARizona Speed and Marine Cold air,
BBK Throttle body, Dynomax UltraFlows,
2.5" full duals,Transgo Shift kit,
Posi , Eibach springs , Police sway bars. 17x9 ROH Impala SS wheels , SS grill, and lots O woodgrain.

Good for a low 15 , with some gears , high 14 , perhaps I found a home for my NOS kit? hmmm..

Fun Fun Fun
Needs some new gears. 2.73's ewwwww

JM
also have a Fiero..thats unfortunatley not quite as fast

[This message has been edited by Slammed Fiero (edited 12-06-2001).]

JM- thanks for the input. I'm planning on going with an aftermarket wiring harness/computer (I understand from archie that it's the way to go- and no speed limiter). I guess a 'vette computer would work fine... digging up one now.

Still open to more info (I'm a sponge like that...)

[This message has been edited by MinnGreenGT (edited 12-06-2001).]

quote Originally posted by MinnGreenGT: #1. The LT1 uses a reverse-flow cooling system that allows the engine to operate at a more optimum cylinder temp. The LT1 uses "optispark" whereas the TPI uses an old-style distributor(?). The LT1 needs to be moved over 2" in the engine compartment- why? Other than that I'm unsure of anything else for #1. {snipped} It's going to work out like this... I can get an awesome deal on an LT1 with 12k miles on it from a Buick Roady ($200 running with stand). I'd like to do a basic rebuild (maybe more?) and use an Archie kit to drop it in. Should I spend the extra cash (typically $300-500) to get a set of Aluminum LT1 heads? Or should I wait and do that later? I'm not going to do anything drastic to the car to begin with (I need it drivable while I'm saving cash), but in the long run I might be investing in a NitrousNX kit as well as some other performance stuff for it .

#1 ... The reason the engine MUST be moved 2" is because of the water pump!!! It is driven off the cam and HAS to be used.

Second ... make SURE the engine out of the Buick is a LT1 engine!!! And not the Y99 (?) which looks exactly like the LT1 BUT is only a 4.3 V8!!!!!! (265 ci)

I have a friend building a street rod and got one of the Y99(?) engines by expensive mistake ... NO ONE wants the 4.3L version. They were used in lots of Police cars and my friend thought that if it was in a Police car, it would be the LT1! WRONG!

I believe the VIN character for the small engine is "D" but I'm trying to remember back ~ 6+ months ago when I heard his tale of woe.

One thing about the aluminum LT1 heads ... they are cheap! I bought a set by mistake (thought they were L98 (TPI) heads ... almost couldn't give them away! They go for < $300 all the time on eBay.

Paul

Paul- thanks for the info. I've never heard that before, but I know for a fact that the motor is an LT1- it was pulled from the Roady by a certified GM tech (very good friend from HS) at a local dealership (the reason it was pulled is shady, so I won't go into details). But it has been certified as a LT1 (although I haven't seen it personally yet... probably this weekend). I will double check the block casting to verify it's authenticity. Thanks agian!

keep 'em coming!

www.fierolt1.com

the guy has a ton of great info on the swap, i believe he did it for less than 10k including the car. i believe(if i read the site correctly) archie will do the modifications needed to rear axles for around $525... of course, who knows how long ago that was...

good luck with the swap, in my opinion its the best out there! *runs and hides from the n* guys*

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87 Fiero GT
1991 Jeep Cherokee

AIM:Spektrum117
And no! i'm not gay dangit!

In a Fiero...it is really really REALLY FAST.

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So, the LT1 doesn't have the water pump drive in the wheelwell? Also, other than relocating mounts and different axles, any other changes required to use an LT1 vs. L98?

I'm thinking about getting an LT1 for my Formula, and updating it with LT4 heads, LT4 Hot Cam, etc.

Anyone know what has to be swapped to change an LT1 into an LT4? Heads, throttle body, cam, rocker arms, ECM, anything else?

quote Originally posted by MinnGreenGT: Thanks to all in advance for your knowledge and resources!

Wow, this is really a cool thread. Only a few posts and you've already been supplied with a wealth of good correct information.

Let's see if I can add a little info without repeating a bunch that we already have.

Regarding the Roadmaster and other full size RWD GM cars that have the LT1's. As you've been told some of them are 4.3 Liter V-8 engines. Many people see the LT1 top end on the engine and assume that it's a 350 (5.7L) engine. The only way you can know for sure is to inspect the engine block. Back on the rear of the engine behind the left cyl. head the engine size is cast into the block. See picture below, in that area it will tell you if it's a 4.3 or a 5.7 engine.

Difference between LT1 & TPI (this will also answer some of the other questions that have been asked).... Let me add this to what has already been said. A TPI engine is based on a "normal" SBC engine. WHAT do I mean by "normal"?? When the LT1 came out, it was the first SBC engine that had the distributor mounted on the end of the crankshaft rather than in the top of the intake manifold & it was the first SBC to use a cam driven waterpump instead of the belt driven waterpumps. Because of it's external appearance somepeople think that the LT1 has an electric waterpump, but actually it's driven from the back side by a shaft from the cam gear.

Now as you've heard, the LT1 has to be moved some 2" to the left in the car and the "normal" SBC can be mounted in the original position. The main reason the LT1 has to be moved over in the car is that the total length of the engine assembly (when it'scomplete and ready to go into the car) is some 3" longer on the LT1 than it is on the "normal" SBC. This extra length means that the hardware on the front of the LT1 engine will interfer with the suspension componets unless you move the engine to the left in the car. You can see the difference in these 2 pics.

I hope this helps.

I'm sure there are a few other points I wanted to make but I need to re-read the thread to remember what they were.

Oh yeah 2 more things...

If you are looking to get an ECM..... give me a call and I can help you avoid buying the wrong one, or call Mark at Street & Performance and tell him what you're doing and he'll tell you which ECM best fits your needs.

Also..... If you're going to use the "Hot Cam" in an LT1 or LT4, you will have to use MAF..... that cam is too radical to use with MAP.

Archie

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Just how fast do you want to go?

Thanks everyone for your input. I knew that this would be the place to get the info I needed.

Archie- any words of wisdom or ideas regarding the tranny? I'd like to stick with the 440T4 OD tranny I have, but I'd like to find out more about how you "beef-up" the automatics?

BTW: The email I sent to Pat's address is bouncing back an error. Any other info on his current whereabouts?

quote Originally posted by MinnGreenGT: [b]Thanks everyone for your input. I knew that this would be the place to get the info I needed. Archie- any words of wisdom or ideas regarding the tranny? I'd like to stick with the 440T4 OD tranny I have, but I'd like to find out more about how you "beef-up" the automatics? BTW: The email I sent to Pat's address is bouncing back an error. Any other info on his current whereabouts?[/B]

I have not had any luck getting ahold of Pat letely either.

I know the 440 would adapt to the engine just fine & that we can get some axles to take care of the 2" that the LT1 would need to be moved to the left.

The only real difference with the Lt1/440 combination would be in moving the driveline to the left in the car (as required by the LT1 engine). As you know the 440 it a bit "bulkier" than the 125 was. Because of this I would think that some trimming or notching of the engine cradle can be expected.

Modification of the transmission?.... I'm not an automatic transmission expert, in fact I've never had one apart. When I get an automatic trans. "beefed-up" I send it out to an expert. The guy I use and recommend is Jim Paquet at JPT Transmissions in Eaton Rapids, MI. Give him a call at 517-663-0578. This is the same guy who built many of my customers' transmissions including Pat's car.

I hope this helps.

Archie

Thanks Archie- that's the info I was looking for!

Forgive me if this question is too far off
topic. But what are the considerations for
shortening the short side axle? How short
can you go without affecting cvj wear? What
effect does shortening the axle have on
suspension?

quote Originally posted by Orville: Forgive me if this question is too far off topic. But what are the considerations for shortening the short side axle? How short can you go without affecting cvj wear? What effect does shortening the axle have on suspension?

You can't shorten the axles...... you can't cut a section out and weld it back together. A person needs to make a new custom length axle. Whenever we have talked about shorter or longer axles these have really ment customer length axles.

The new axle can't be much more than 2.5" shorter because the C/V boots touch each other.

The suspension geometry is uneffected by axle length.

I hope this answers your questions

Archie

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Just how fast do you want to go?

Thank you Archie.