I have two TA's a 91 GTA with 305 5 Speed and a 1992 TA Convertible. I have been trying to keep the 92 close to original since its fairly rare for shows. The 91 GTA has an original TPI motor and runs ok but it smokes when started. Its tired. I want to make the 91 my driver because I think it is a cool looking car. After finishing the suspension mods, it really handles well. I have been looking at LS1/LS2 vs putting in another iron block engine and then trying to figure out what to do when the fuel system. I also have to pass emissions tests where I live. I have looked at Hawks and talked to Bruce and seen the "Blue Car (I thought the supercharger was great)". However, I am trying to figure out the way to go on this. The weight of the LS1 is an advantage. I have built about 150 engines, but have no LS1 experience at all. I built the engine in the 92 TA. The 91 GTA also has a manual T5 World Class transmission and I just had a couple of gears replaced. I have a feeling that the tranny will have to go. They don't seem to be built for horsepower. I don't mind doing the work and spending the money. I just want a car that is fast, legal, and reliable. Any comments?

Doug

 

I vote for the LS1, they are becoming a little easier to find now used, and already have alot of conversion parts to help the drop in. They are not too different in the rebuild, most of the information on them you can seach around for like from LS1.com or LS1tech.com The LS1 + T56 seems to be the most popular swap, but i hope what ever goes in the rear is going to be babied or built to handle it.

 

OK, I need to clarify some things here. I am new to this site and have been looking around. In my last message I stated that I was looking at an LS1 vs the old style 350. This is my second 3rd gen engine project.

If I go with an LS1, I will buy a crate engine. Yes, I have the budget for it. I don't believe in buying junk yard engines. The installation of this engine is a real pain especially when considering things like air conditioning (I live in Texas). I have seen the Ls1 with the Supercharger and really like that set up. The other thing is that I need a different clutch and tranny setup, which is more cost and trouble. Looks like the driveshaft and rear end will be OK. Headers appear to be impossible and I would be stuck with the OEM manifolds. Enough on the LS1.

The other choice is to build a conventional 350. I looked at the ZZ4 with the aluminum Vortec heads. (I do not fully understand Votec heads. Can someone educate me on the differences and emmisions issues?). This engine has a strong bottom end. The Vortec heads have a different intake bolt pattern and I found the TPI base for them. I thought about buying a 4 bolt main short block and using Edelbrock's performer heads. I would like to keep the TPI setup (it looks good at shows), but it appears that if you build an engine that develops max power at 5000 RPM, and the TPI loses flow after 4400 RPM, then you defeat the purpose. I was taught that you want your max toque at higher RPM's so you can take advantage of gearing. So, if I stay with a TPI setup, then I need more flow, therefore I am thinking a Supercharger again. I keep hearing the advantages of the TPI low end torque and completely do not understand how the runners affect this. Guess I am dense on this one. I understand how the runners restrict flow at high RPM. (We used to mount carbs close to the heads if heat would allow.) I would consider the Accel Miniram or any other suggestions. I would like to keep the basic ECM. The obvious advantage of this engine setup is that all my accesory devices fit, like AC, and I still get a lot of power. I can have headers on this car. I can deal with the computer myself.

What ever engine is selected, it will probably be tested on a dyno before it goes in the car. Its a lot easier to tune and in the long run saves time and money.

One other thing, this is a T-TOP car (I don't want to hear it.) and I am concerend with the frame strength. I have installed the Wonder Bar and replaced the door bushings so everything is nice and tight. Its amazing by doing these two things how the rattles start going away. The doors are part of the body integrity. I have not selected sub frame connectors yet and would like advice on that one also. I think welded is the only way to go. My convertible had stock sub frame connectors.

My goal is to build a street machine that looks stock on the outside, but will surprise those nasty old "Stang's" out there. I would like to see the car do high 11's or low 12's in the quarter. I want this car to be reliable and pass an emissions test. I have some budget to play with. Tell me what your configuration would be. Just remember that I do not want this conversion to take forever.

I used to race and build engines 20 years ago. I was a carb guy and the tools to make predictions did not really exist then. I like playing around with the computer programs on the ECM. You end up learning a lot from this.

Go Easy on me.

 

I honestly don't see the wonderful side of LS1 buildups, they make good power...but NOT for the bang for the buck. They have their own quarks that make them unappealing to me, at least until the price falls. (I have your sort of budget as well but just can't see the rainbow on the horizon)

If I was in your shoes, I would look into a 383 buildup- 427 if gasmileage and price are no a concern. On my nova I had a 427 running a 950 holly, switched over to a demon and gained 32hp and 17ft lbs. So I always recommend demon now.

On the T-Top's, subframe connectors at a bare minimum...I keep hearing good things about S&W racings subframe connectors (www.swracecars.com) bit pricey but they look good. I have an 11second 3rd gen (before the motor blew ) w/ ttops and don't have crazy frame twist...I think it is in a lot of these old timers heads for the most part...

 

IT really comes down to what YOU really want to do. i'm doing a ls1 swap as we speak and i dont think its all to high in price as long as you go with a used engine. I dont have a problem with buying a used engine, not any different then buying a used car, you just have to check it out. but since you want to go crate then yes its going to get pretty pricy. If your going for the most bang for the buck then i would go with a 383 or 406 set up. Nice thing about the ls1 is weight, gas milage, can be made to have a lot of power. I can see both sides but like i said just comes down to what you really want.

 

I was in your shoes a year and a half ago, not sure whether to build up the TPI or put in an LS1. (And since I am moving later this year to California, emissions was also a primary concern for me).

After a lot of research, I chose to go the LS1 route. Started saving up and buying parts, had just about everything I needed when I came into a little money and bought an LS2 402ci stroker shortblock. (By the way, I'm having Bruce do the install labor, also)

For YOUR situation, I would recommend buying a stock LS1 or LS2 crate engine. The TPI buildup with a blower SOUNDS good, but ultimately you are going to have more money into it than you would with a basic LS1 or LS2 setup, and be right around the same performance level as a stock LS1, maybe as much as a stock LS2 at most.

Going the stock LS1 route, you will need the following:

LS1 crate engine
LS1 PCM
LS1 customized wiring harness
T56 transmission
Engine and trans mounts
Custom y-pipe with O2 sensors
LS1 exhaust manifolds (or the new LS2 manifolds, which flow better)

Those are all the big things. For CA, I also had to install a 4th gen gas tank with all the EVAP equipment. But really, that's all there is for what I call the "basic" swap. (Of course, there are always the "little things" which I am sure you are aware of that occur in any swap/buildup). If you keep the engine stock, the rear end, driveshaft, brakes, etc. will be fine.

For the wiring harness, I highly recommend John Spears from speartech (www.speartech.com,) John has a 3rd gen LS1 in the 11s himself, details and pics are on the site.)

3rd gen LS1 headers are not impossible - several people here have made their own and Bruce will have them for sale this summer. I'm assuming that passing emissions in your area will still allow them to be used (CA does not!)

The beautiful thing about the LS1 engine, is that right out of the box they are making a bit more than 300rwhp (LS6 & LS2 is even higher), BUT they are so EASY to modify and dyno TUNE and get up to big power numbers if you want to! The only drawback is that if you go beyond stock, you will want to put in a better rear end, brakes, etc. But that is no different than if you built a big-block chevy for big power numbers, in my mind.

Ultimately, I guess it comes down to what you want. The LS1 will give you as much or more power for the same money (maybe even a little less) as any supercharged TPI engine buildup I've seen, with much more expandability than the old small blocks will ever have. Carbs are obsolete (in my opinion) - and so are the early EFIs like TPI. You can build up the TPI and throw on a blower, and you have pretty much maxed out its potential. The newer engines (LS1, LS6, LS2, and soon the LS7) are capable of more than the SBC ever was, while EASIER to pass emissions AND make power with.

If I were in your shoes, from what you've stated as goals, I'd put in an LS1 with a decent cam package, or an LS2. High 11s? Easy.

PM me and I can give you contacts for a few places that deal in crate engines (stock or custom-built LS1 and LS2) that have excellent reputations within the LSx community. Hope this helps you.

As to the sub-frame connectors, Kenny Brown and Spohn seem to have the best reputations. I went with Spohn, myself.

(edited to correct typos)

 

Having owned a few f-bodies and sbc chevys, here is my input:

If you have the budget, why not build a stout sbc (you already have the experience) using a 1pc. block or a crate motor. Find a Lt1 T56 with all its swap parts, and be happy. You'll have a solid motor, solid trans and a powerfully, no guess work combo. Stuff will fit right and be straightforward.

 

First, I would like to say thanks for the comments so far. There are definitely pro's and con's here for a small block Chevy or the LS1. I am intrigued about building a stroker. I am also intrigued about the LS1. I just know that the LS1 swap will be a major pain. The guy that moved to California makes a great case about the emissions.

One other thing about myself. I run a company that supplies the auto industry with technology and I still do some programming. The computer for the LS1 has much more capability than the old thirdget ECM's had. I am going to download a custom program into the ECM on my 92 convertible to get a little more out if. Biggest problem with that one is dealing with the Speed Density sensor, which I hate. The newer LS1 computer could probably be put into all kinds of modes (Gas mileage more, race mode, etc...).

Anyway, if I can slip away tommorow, I plan to go visit the shop that did the machine work on my 92 convertible, and get some inputs there. The person that runs the shop sits on the local board for ASE. By the way I used to have NIASE, but that was a long time ago. I might get a junk yard LS1 and rebuild it myself. That might be fun. I just can't see putting a used engine in the car when there is a lot of work to do. One thing I have learned, dyno and tune the engine before it goes in the car. That is a money saver in the long run. I learned lot of hard lessons putting together a custom TPI engine with a special cam and trying to characterize it with it in the car. I am still learning some lessons here.

Thanks for the suggestions and keep em coming. I am learning a lot from you guys.

Doug

 

Igor mentioned the LT1. Why do I not find any LT1 crate engines? I know a little about the reverse cooling. Am I looking in the wrong places?

thanks.

 

I have had both...I find the LT1 very capable, and its stock computer is reprogrammable and powerfull. I like Lt1s. Am thinking about an LT1 vette.

 

I am probably going to catch hell on this update, but I decided to put it out here anyway. As I mentioned in a previous messge, I was going to visit someone who I consider an expert, especially in Chevy Engines. He runs his own machine shop and sits on the local ASE committee here. He did hthe machine work on my 92 TA 305. He has seen everything. I won't give out his name because I don't do that without permission first.

I drove my 91 GTA to his shop and we talked about engine choices for my car. His recommendation was to stay with a conventional SBC engine and not do the conversion to a LT1 or LS1. He like the ZZ4 and maybe the ZZ83 (425 HP @ 5400) with the aluminum Fast Burn heads (What kind of fuel injection?). He said they burn clean although he does not like aluminum heads much, mainly because of durability reasons. There is always the electrolysis problem (Seebeck Effect) when you mount unlike metals together. I have taught a class in this area before. You have to watch this carefully and it can be somewhat controlled with special coolants.

I know these will be fightin words for you LT1 guys, but he absolutely said to stay away from these. Apparently the LT1's have a lot head problems and he keeps a spare set of LT1 heads in stock. Appraently they warp or crack but he did not want to get into a lot of details there. Based on his reaction, I was not going to get any more info on a LT1 conversion. I found it interesting that hardly anyone will sell a LT1 crate engine, but you can fine high horsepower SBC's and LS1/LS2 series easily. I also have a friend that has a 95 TA, with the LT1 and 100K miles, and he has had good service out of the car. Anyway, I do not like the LT1 option.

Regarding LS1's, he thinks they are a good engine, but have to be babied. I agree with that, mainly because it is aluminum. I am always concerned with oxidation and wear. They are very flexible in configurations and run clean, but may not be very durable over the long haul. There is not enough history yet. I realize that there have been great strides in metalurgy in regards to aluminum. I am sure that every LS1 owner out there is going to disagree. However, think about this. Does anyone remember the Chevy Vega with the Aluminum alloy engine? I used to work on those lovely engines (piece of junk). The water jackets oxidized badly mainly because of poor maintenance, and we ended up pressing steel sleeves in the cylinders so they would hold up. I doubt you will find any of those anymore. Also, when I rebuilt my 92 TA engine, the base plate for the TPI was practically unusable and we had to make repairs to it. I acquired another base plate that was also damaged in the water jacket, and we welded some aluminum alloy on the plate and machined in back down and it looks like new. I keep it has a spare. Because of the maintenance issues, I would only buy a new LS1/LS2 crate engine. The LS1 conversion is still in the running for me. I just don't like the coversion process much.

I plan to do my conversion this summer, whatever it is. If I do the LS1, I will try and document a guide from beginning to end that might help someone else out there. I would still like to here any comments or suggestions.

Thanks, and don't beat me up to badly. I know a lot of people are going to disagree with me.

Doug

 

It's hard to disagree with your decisionmaking approach, very facts-based.

I swapped an LS1 and I love it. However, if I had it to do over again I'd stick with a gen-1 SBC similar to what you're describing. The LS1 is a sweet engine and all, but there's nothing magic about it.

I'd start with a regular 4-bolt main 350 smallblock, flat-top 2VR hypereutectic pistons of whatever brand, decent crank and rods. Probably use an L98 2-bolt block and have the mains splayed.

I'd use a solid-roller camshaft and Comp Endure-X (sp?) or Morel lifters. Have to adjust the lash annually but it's worth it.

For heads, I'd go with GM FastBurn pieces but upgrade the hardware accordingly. Have a shop clean up the ports but not touch the chambers. I ran AFR 190 heads for two seasons and hated 'em...oil returns are tiny and put the "waterline" above the valve cover gaskets, a leak waiting to happen.

For intake and fueling, I'd go with a TPI harness and ECM and either a Stealth Ram or Mini-Ram intake.

(basically the engine I had before the LS1 but with a solid roller cam and no aftermarket heads)

 

Why would you catch hell? You aren't attacking anybody, just discussing research and facts.

I heard a lot of negatives about the LT1s also. I wouldn't be against buying a car that already had an LT1 in it, but to buy an engine for a buildup project, SBC or LS1 is, in my opinion, the way to go.

Like I said before - I think it really depends on how "far" you want to take it. If all you will ever want is 11's in the 1/4, then an SBC buildup is probably going to do just fine, and maybe simpler. Most people aren't "satisfied" though - they seem to always wish they'd gone a little bigger, or want to have the option to expand further later. For that, I personally feel the LS1 is superior.

As to the longevity of the aluminum engines, there have been huge strides made in technology - this isn't the same as on old Vega engine, by any means. A LOT of r&d went into the original LS1s to make sure they could handle the power and still be durable, and from my understanding the LS6 blocks are even better in that regard, and the newer LS1s are fashioned with the same block now. The LS2 blocks are even stronger. Mileage wise, I have heard of several LS1-based cars still running like new at 150k miles+. Perhaps it is a risk to go LS1 because there aren't thousands of "old" LSx engines yet, but ANY engine buildup involves a certain amount of risk, no? From what I've seen, I think you can certainly get comparable engine life from these new engines as the older SBC technology got.

Good luck in your decision making - I really do believe that it comes down to a personal choice for each person; no two projects are the same.

 

I absolutely agree! Any engine, with the right valve-train of course, has the ability to run 10's in the quarter. It all comes down to personal preference... and how much you're willing to spend to get you there.

 

i figured i would chime in and say that im pondering all the same stuff for my 91 Trans Am. but i feel theres a few things said here with an obvious bias towards them (not that you have but a biased that was told to you).

the lt1 only has problems warping heads when the head gasket lets go just like any aluminum headed engine. from what ive heard the head gasket goes around the same time as the water pump and may be connected in some way. lt1s have been proven to be as durable as the Gen I SBC so i wouldnt really worry about warping heads. if its that much of a concern read on an lt1 board what head gaskets they reccomend and use those while you build it or before you swap it in.

the ls1 is WAY stronger than what most on any board want to believe. the stock crank has gone into the low 8s at 170mph with twin turbos. and he does it routinely. (search for harlan on ls1tech.com) i believe he uses a stock block also. i havent heard of any coolant passage problems with the ls1 like the Vega had. i also disagree with them needing to be babied. that sounds like its spoken from someone with an iron block bias (like i mentioned earlier)

as far as bolting 2 unlike metals together, i think great strides have been made there. even the new silverados run an iron block with aluminum heads (6.0 liter engines) and i havent heard of any head warping problems there. the 03-04 cobras run an iron block with aluminum heads and i havent heard of any head warping problems there either. i agree that there is the possibility because of the different characteristics of the two metals (iron and aluminum) but its something i wouldnt worry about personally.

and lastly as far as mods here goes. speartech has gone in teh 10s with a stock shrotblock, stock manifolds and stock heads (i believe) with a magnacharged ls1 and a stalled auto. headers should be here soon from Hawks (im waiting to see prices and pics) or you could make your own (a local guy is doing that in his 91 GTA with a heads and cam ls1). the lt1 is a direct physical bolt in and would use many of your same parts (exhaust ect) and could even use SBC grind cams.

let me know what you come up with because im still pondering on this.