DrummerDad

I have a lead on an LT-1 for a good price, and a friend at work is gonna help me rebuild/install it. We do helicopter sheetmetal/ and custom wiring, and he is a certified welder and races a 9-sec truck. Anyway, I think we can pull it off with our collective knowledge and resources.
Itll be spring till this happens, but my question is on the exhaust. If Im going to put an LT-1 in, I would like to have headers on it now so I dont have to do it later. And I might as well do a complete exhaust, unless it runs the price to high.

Heres what I have in mind. Tell me what you think.(3",true dual)
Hedman Headers(for a 3rd gen, long tube, 1-3/4, by,3")
2-Dynatech catalytic converters (3" in/out, no air tube)
2-Delta Force Flowmaster Mufflers (40 series, 3" in.out)
X-pipe(may make own, may buy)

So the plan is to install the headers, trailer the car to a muffler shop, and have them weld the rest in. The only reason we cant is we dont have a lift, or anyway to get the car high enough. I want true duals. Will all this work? What actual headers do I need? Do I buy for the car,or the engine? The exhaust ports are still the same right.I dont have to pass an emmission test, but a visual can be done, so I need to retain at least 1 cat.

84z28350

I wouldnt really suggest 3" true duals for a street car depending on the ride hight of your car its going to be pretty close to the ground. i have 2.5" lakers with no mufflers/cats and huge tires and i drag the pipes all the time.

DrummerDad

I was going to try to fit them in the factory exhaust channel. Side by side you know. Im thinking the cats might pose a problem,I was going to stagger them, but the rest should go. I was thinking about 2-1/2" but all the good mufflers and cats are 3".

NastyL98_T/A

dual 3" is a waste on a TBI car, not worth the hassle. You'll get the same performance gain with dual 2.5" or a single 3''

firebirdjosh

iTrader: (1)

Are you retarded? The first line says he's installing an LT1 and he mentions it again a few lines down. Also dual 2.5" flows more than a single 3" so he wouldn't get the same performance gains.

Anyway, dual 2.5"s do flow alot so it may be best, but if you have the skills and money to do 3" then I say go for it. LT1 heads have the same exhaust ports as the 3rd gens (as far as I know, double check that for sure) so 3rd gen headers *should* fit. If you can't get the car up high enough to work on (I couldn't) then just put everything in place, tach it, remove it, then run a bead and reinstall it. You may be able to get away with 4 tall jackstands if you don't mind crawling on the ground to weld.

DrummerDad

My bud keeps telling me we can probably get it done. Im not sure. What about over the rear-end? I guess a slip joint with a clamp would work. I was just trying to save as much money as possible. And I figured even the stock exh.manifolds would require modification on the LT-1. And headers arent to bad on the wallet(about $200-$400). I may have to stretch it out a little, by buying some parts, and putting off the install for a year. I dont want to rush and screw something up.And I dont cut corners. We are going to make our own SFCs and Tower brace. I like the ones from Spohn, but thats money I can spend on something else, like a fuel pump. Hes also wanting to make a torque arm, and a panhard bar. Like I said we have access to all types of heim joints and bar stock. And I can purchase it all at a discount as an employee.

Mkos1980

iTrader: (8)

Duel 3in would be way over kill on an LT1 even. Probebly kill performance too.

NastyL98_T/A

STFU Corky. He says "IF" he puts an LT1 in. How does that make any difference anyway? Still wont make considerably more power than a single 3". Get back to your bench racing you Dweeb.

DrummerDad

Even if I might put a supercharger on it later? Or N2O? And If I go to 2-1/2", can I drop it into a single cat. That is one of my biggest concerns. The cat. Maybe a 4". I just dont like doing anything more than once. If I upgrade the engine later, like I want, I might need more exhaust flow. My dream is to upgrade to the LT-4 kit thru summit, it has Heads-Cam-Intake. It supposed to be a stout combo, and maybe(wishful thinking) a supercharger. If not I will spray it, but not alot. I plan more on top-end(legal) racing and maybe a little road course. N2O is not as effective on the road course, as a S/C. Both flow more O2 thru the engine. I dont want to choke the engine. Anyone have any suggestions. The engine should make roughly 350-375 h.p. off boost or spray. That is what im planning for. Better to overdo than underdo.

Air_Adam

If you plan to drive it on the street, I would stick with a 3" single exhaust system...

BUT... get a pair of 3" cutouts to put onto the collectors. Then you can open those up at the track.

This way, it will be much less uhh... hassle? to fabricate the exhaust and also to drive around town, because you'll have better ground clearance.

Mkos1980

iTrader: (8)

NickT from 3go board has a 87 Iroc with a 377 running an F1 Procharger with 18lbs boost. He has a single 4 in and thats it. 2.5 duels is the way to go. look at the GMMG phase 3 car with 600hp. Its still a single 3 in. Now that motors a differant story but if duel 3's would have helped more I am sure they would have done something differant.

Z28ricer

iTrader: (2)

Aside from everyones bench speculation and no real experience with half of what you want.

The LT1 has D shaped exhaust ports, you will either want hedman p/n 68469 for longtubes or 68479 for shorty's they are a 1 5/8" either way, I have found that SLP 1.75" shorties arent meant for a D port however they will more than completely swallow the LT1's ports. On the same note hookers 2210 longtubes should not have a problem doing the same as I have a set of 4th gen hooker longtubes and they dont seem to be changed any for the D port they just have a big square window.

The hedmans are going to be the cheapest @ 180$ from jegs or summit I believe. I'm sure a dual 2.5" exhaust would do well for you if thats what you want, and I highly doubt a 3" would end up hurting you if you wanted to go for that also. Please keep in mind ground clearance underneath will probably suck badly and thus the main reason I try to stick with a single exhaust. Transmission used will also come into play here, and those crossmembers with the cutouts may be something to look into.

As far as your ideas with the LT4 kit, you'd be much better off with many other choices out there, the kit wont get you as much performance nearly for your money as a lot of the other available options, also running that with a blower would also be a backwards step as it is going to raise your comp to around 10.8:1 as if the stock 10.4:1 isnt bad enough for boost already on the stock crap pistons. Take a look at the trick flow LT1 heads if you are set on boost as they have a larger 64cc chamber which will help you lower your compression a bit, as well as have around 290~ cfm capability.

Also keep in mind you wont be able to just bolt a 4th gen LT1 blower kit right up.

DrummerDad

Thank you Z28*****. You just answered some of the questions I have been trying to deal with.

I have been trying to get some part #s together, and these headers are straight up confusing. I may go with the shorties, so I dont have to worry as much about the collector hitting bottom. And for ease of install Im really considering 3" single. Itll also be cheaper. And I think we can install it.

And as for the LT-4 conversion, Im almost positive Summit sold a conversion kit they claimed made almost 400h.p. I cant find it now, but im not going to spend the 1500-2500 bucks for the G.M. LT-4 parts, for a measly 30 h.p. gain.

I am still trying to get a clue as to what I need to do to get this pulled off. Jamie(the friend at work) wants to put the engine in in the spring, If I can get it. Im trying to see if its gonna work. I think hes forgetting I also have to re-wire it, and change the fuel pump, work out positions for the A/C compressor and alternator, routing for fuel lines, and radiator hoses. Its definately not a bolt in.

Thanx for all the info.

Z28ricer

iTrader: (2)

Quite a few of us here have done the swap, i've done it several times myself.

The LT4 kit from summit is listed as 425 hp or so, it is just stock LT4 heads and intake, but the "Hotcam" and again there are much better parts available for the money. Good kit, just better avail for your dollar.

Let me know if you need any info on the swap.

firebirdjosh

iTrader: (1)

If you think you can tuck it up so ground clearance isn't a problem, then I'm not sure why everyone says " 3" is good enough". More flow in this case is more power... why do you think cutouts lower your time in the quarter mile? What about the guy that posted his dyno of his V6 gaining quite a bit of power going from 2.5 to 3" when everyone said it wouldn't make a difference?

91_5.7_TPI

iTrader: (2)

Hey, DrummerDad. I tried the duals around here local, and couldn't get them done. If you can get it, let me know. I want some. Hey, I looked into the LT-1 / LT-4 camparo and I found that this is better in many people's opinion (including mine). Just thought I'd let you know.
No new news on the LT-1 yet.

A question - If the LT1 exhaust ports match up to the older style headers, will an LS1? I plan to do a LS1 swap. Thanks

Fevre

No, LS1's have even spacing between the exh posts like big block's and rustangs.