I have a ‘93 lt1 and I’m gonna drop the cat back out but I’m curious if I get long tube headers catless will this set a CEL?

 

Just run some high flow cats.

 

It shouldn’t throw any codes. When I went long tubes I removed the cats and the resonator. Straight pipe back to Corsa mufflers. Runs great, no codes, sounds awesome

 

I don't believe there are downstream O2 sensors on these until like 96 or so?

 

FAUEE, you are absolutely correct. The 95 is the first to have a downstream sensor but it is not functional so it can be eliminated with no issues. Ask me how I know. LOL

 

I can’t wait to do this myself. I agree with the others, she’ll never know the difference. Match it with some other bolt ons and have your prom tuned to match your bolt ons. LT1s can pick up quite a bit just with a tune on a stock car. Tune to match will get the most out of your new exhaust.

 

any recommended tunes for these cars that are plug and play?Or do I need to send my ecu in for tuning or how would this work? My plan is to put some long tube headers on without cats and if its too loud throw an x pipe and other 2.5 inch and some tips on it ? Would it be dangerous at all to have the exhaust running straight out of the headers? I have a oil leak which I think could be rear main seal when I had it on the lift today and I’m not sure if I’ll get any flame from the headers and I don’t wanna get a fire and I’m curious how running catless headers will smell… will it be overbearing smell of gas? Other than that my plan is to upgrade torque converter to a 2200-2600 stall and throw a 3.54 gear in the diff, with these upgrades what sort of tune should I be looking at?

 

So you are talking about running straight exhaust directly out of the headers. Does the concept of carbon monoxide infiltrating the cabin not worry you at all?

i run the headers directly into the stock exhaust minus the cats and the smell is so obnoxious that I am looking to add high flow cats. Sound is perfect for me. Sounds strong when pushed but still allows me to have a conversation with my passenger.

 

okay so I ordered an x pipe and tail pipes for when headers arrive and I’ll have the shop weld some pipes to make it a full system, but what about for tune? How does that work?

 

As far as the tune, there are a couple plug and play options. Your PCM is a bit easier than the 95-96 cars. You have a prom that can be pulled out and sent to a tuner. You provide them your particulars; stock, heads and cam, headers, exhaust, etc etc. they send it back and you plug it in. PCM for less and LT1 PCM tuning are companies that people have had success with. Check out their websites. I am by far no expert on tuning. Any tuning I have had done was live with a dyno and it was not on a corvette. I also played with smarty tuners on my Cummins diesel myself, but that’s about it. Email Solomon at LT1 PCM or call PCM for less. They have been around the LT1 world for years and years. You mentioned an oil leak. Things like oil leaks and any vacuum leaks, old or bad sensors, should be addressed before doing anything. The tuners will flat out tell you your engine should be as healthy as possible in stock form before any tinkering is done. Your leak in the rear COULD be a rear main but I would also suspect the rear intake manifold seal as well. That is a known major source of leakage that many have been fooled thinking it was the rear main. With the age of our cars, the intake, valve covers, oil pan, and front seals should be done. Oil on headers is worse than on manifolds because the manifolds are thicker and thermally insulate a little better. I would not run it on open headers unless it is to get the car from one end of your garage to the other, getting it on a trailer to go to the exhaust shop, or something similar. Gears and converter stall speed are particulars you would tell the tuner you have. As far as smell with no cats… have you ever been behind a pre emissions era muscle car? Expect that sweet combustion odor. I can’t stress enough having your car squared away before you do anything. Tuning typically advances ignition timing and leans out the AFR a bit, which can really harm your engine if the air fuel ratio isn’t where it should be to start with. Sensor such as the MAP sensor and O2 sensors should be new or verified in good working order to get accurate readings for air fuel ratio on your car, which I believe is a speed density system. The later cars were MAF systems but the same rules apply; all sensors contributing to readings that control AFR have to be right. My car for example, has cats and the stock exhaust. I already have a substantial sweet odor which I think may mean it’s running rich. I have new sensors to install but haven’t had the time. I also have new fel pro seals for the entire engine and the entire ignition system replacement parts on a shelf waiting for my life to slow down lol.

 

So for the sensors do I need to make sure they’re reading in a specific range or just functioning? I plan on having a shop just cut off my mufflers and diagnose my oil leak and give me an estimate on the repair, because down the line I plan on dropping a crate motor in which is why I want to do rear gear, torque converter, trans cooler, and exhaust before so it’s all ready for the motor to drop into, at the time of dropping in the crate I’ll have them upgrade my trans too but this is prob a year down the line, for now I just want the headers gear and torque converter but what sort of gain do these engines get stock with a tune?

if the o2 sensors aren’t working then won’t it set the cel?

 

pulled my car into the shop today and guy I work with said it looks like it could be manifold gasket leak… how can I test/differentiate between a manifold gasket leak and rear main leak when there’s already oil all over the place? Would it be worth it to just replace all seals on the motor or should I just keep filling my motor with oil until I can afford a crate and drop in a crate motor?

 

You have already mentioned you have ordered different mufflers and an x-pipe, why would you cut up the current stock system instead of just removing it. It does have resale value when not cut up.
Finding your oil leak can be done using a UV additive that will show where the leak is when exposed to a black light. Readily available at your local auto-parts store.
Why spend the money on a tune for the current engine if you are going to replace it with a crate engine next year and will need to go through the process again at that time?

 

because I’m not sure if I should buy heads and build a top end with this block or if I should just buy a crate motor, what’s the best way of making 450 hp for cheaper

 

awolkenstein, I would not bother with a tune until A: you build this motor or B: you drop in a crate motor. Unless you are leaving it as is for a while and you fix the seal(s). If you really wanted to do the tune now and just fix the leaks, seals are cheap. The manifold is not that difficult. You have to disconnect the fuel lines and remove the fuel rail and TB. The injectors can come out with the rails as one unit. Just be nice with them. To reseal the manifold get the fel pro LT1 intake manifold gaskets for the sides and use permatex “the right stuff” to make your front and rear seals on the china walls. This should work really well and eliminate a lot of your problems. For like $150 more or less, you can reseal the entire thing if you want to. I’ve begun to do parts collection to do mine, and believe it or not, Amazon (ugh) has all the fel pro seals for these engines at rock bottom prices. Like 25% or more cheaper than advance auto. Still cheaper than Advance even with 15% off and all my speed perks coupons. The fel pro kit for the oil pan is really nice because it comes with installation studs that hold it in place until you get the pan on. Just be aware that doing seals can take you down the rabbit hole. If you do the front timing cover seal, the oil pan has to get dropped so then you have to do that one. If you take the pan off, the oil filter housing has to come off to get it off. So you have to do a new gasket and o ring on that as well. Luckily, like I said, it’s super cheap. But if your tearing down that much and considering rebuilding your current LT1, why not just do it once. So you have some decisions to make here. I bet doing the intake will eliminate much of your leakage issues, especially in the rear where you’re noticing most of it. So maybe try that and see. Your question regarding how to tell what exactly is leaking…that’s a hard one due to gravity. Oil runs down the engine so unless you clean it really well and then try to see where it’s leaking, you’ll never figure it out. The intake being up high, is leaking all over the back as it runs down. I’ve heard that you can put some sort of dye in the oil to make it more apparent but I have never done it nor do I know anyone personally that has.

 

If you’re looking for 450 at the crank that is pretty attainable with the LT1. Lloyd Elliot LE2 heads, one of his cams, and him porting the intake to match the heads will get you anywhere from 390-410+ hp at the wheels! On a stock displacement engine. That will put you at or over your 450 hp at the crank goal. If you want 450 at the wheels, you can build the engine accordingly and go to a 383 while you’re at it. That would get you close to 450 at the wheels with a serious cam I would think. What kind of crate motor are you considering? The GM crate motors in the LS variety are awesome and you could build your trans or do a connect and cruise with a new trans. Pricey but man would that be cool. I’m pretty sure they have 4L60 and 4L80 options

 

honestly I was looking at golen engines… https://golenengineservice.com/lt1-performance-engines/

there are setups where I can buy a motor and trans in a bundle to match the power output? How much would it cost to do a build on my current block? Including all seals, can rockets lifters heads and headers? If its closer to 5k vs the 8500 crate motor is definitely build it

 

Golen makes some awesome engines. I have read many write ups on them in magazines and have heard great things elsewhere. I think $8k would be money well spent for an engine you know was done right. It’s really not a bad price when you consider all the machining and everything else that goes into a build. I can’t tell you what it would cost for you to rebuild yours. But I can venture to say you probably won’t be saving a whole lot unless you are reusing a lot of stuff. And who knows what things actually look like inside. If you’re crank journals are ok maybe it won’t need to be turned. Or if it does, how much. Yes oversized bearings can make up for that. Building an engine is a lot and requires doing a lot of things just right, other wise it’s not going to last. I’m all for you going with a golen.

 

Before getting to excited, I would call Chad @ Golen or any machine shop and ask them what their lead time is. I know my preferred local shop is 12-15 months out.

 

Yeah I was thinking if it’s a really well made motor and it comes fully built ready to drop in then it’s worth it. I got a call back from Lloyd Elliot, $2150 for heads and a cam + shipping and then I’d have to buy rockets and lifters still, not sure a good manufacturer or what they’re price is like but that will likely be close to $4k I’m guessing just in parts… plus if I do end up doing a build on my engine I’ll have to redo all the gaskets and seals I’m assuming which involves tearing down the motor, so at that point I guess it’s more price efficient to just buy a crate motor and drop it in since it’s fully built and timed already right?

never bought a crate motor so I’m curious, do I have to get a new ECM? I’d be running either 3.09 or 3.54 in the rear with a 2200-2600 stall and I’d have the trans internals upgraded to match the motor