I'm going to swapping my L99 for an LT1 in the near future and I woould like to konw what mods I need to do to get to 300-325 FWHP. It's not much but I'm looking to keep the factory manifolds and cats. LT1 I'm getting has a good monster transmission behind it capable of much more power. (LT1 is from my buddies rotted out 9C1) What kind of mods can I do to help the LTx be rated for 300-325FWHP? THis engine in my buddies 94' 9C1 ran the 1/4 in 14.6 with a CAI and cat-back and a tune. No internal engine work at all.

 

Join impalassforum.com

There are a ton of b body info on there and you can find it easily!

 

since it has 260 FWHP already you could do:

cold air intake
2.5" CAT back exhaust
1:6 RR
PCM tune

that would get you to 300ish FWHP

lower rear gears and a mild stall TC would then allow that new power to get the car moving faster off the line

 

if buying a monster transmission save your money so you can do the transmission right WHEN this one dies.

I have actually done the L99 to LT1 swap and been down the **** tranny rebuild road. Been there done that, you are free to repeat the mistakes others before you have made OR you could actually use the forums to your advantage and take some advise on how to do it the cheap way, which means RIGHT THE FIRST TIME.

 

This trans has been behind an LT1 for 40k. Actually I lied, it was not a monster transmission, I don't remember the name of the business but it seems like a solid unit so far. I went to monsters site and my buddy told me that was not the company so I'm not sure right now. This is a package deal for the LT1 and transmission. I'm getting a HELL of a deal so maybe this tranny won't last BUT for the money I'm willing to try. I don't have $700 to do a rebuild on my old transmission anyways. Kind of a rude response don't you think? I'm not an idiot, I built my gen 1 SBC by hand and my LT1 too. Not a lot of people can say that. I wanted some friendly advice about what I will need to hit 300FWHP on a stock exhaust manifold LT1. You act like I'm paying a lot for this "Unknown" transmission. It's been behind my buddies LT1 for around 40k and it still shifts great so as far as i'm concerned its doing quite well.

 

Maybe some day she will get gears but I think I'll stick with a converter for now. Probably a 2500 stall converter. What do you think?

 

This is an LT1 question not a B-body related question. I am a member there already but I feel LS1tech has more engine related tech where Impalassforum has more B-body related tech.

 

If you wanted blind praise for whatever ideas you already had you should have opened with that so people would have known how to respond.

So YOU supplied inaccurate information about what the tranny is..........................and didn't like the response.

Now you are starting out by immediately dismissing useful advise ****** has to offer. Then you proceed by saying you want to cheap out on the converter too. If you don't want good advise don't ask for good advise.

Far as the performance of the donor car, sounds fairly normal, catback and CAI are solid mods on a b-body, a lot of guys have gone much quicker without any real engine work, hell I think one guy even managed 12s with boltons without ever pulling the valvecovers.

 

I have NO IDEA where you are coming up with some of your ideas. First yes i did supply false info, ok no big deal. Second I DID NOT dismiss ****** advice, I will use that advice. BTW tell me when I said I wanted to cheap out on the converter? When EXACTLY did I say that? Advice is fine, constructive criticism is fine but putting words in my mouth that I didn't say I won't tolerate. Especially when those words make me look like a dick. What ideas did I already have? I came in asking about the LT1 not bragging about anything. I don't understand where you are coming up with this false information about me. I have no problem with anyone here, I just don't like the rude responses, there is no reason for it. You sound JUST like the Corvetteforum guys, hence why I left that site and found another online Corvette community. Lets get over this highschool girl **** and be adults. And yes I realize mid 14's is the norm but I have seen stockers run much worse as well. My point was that the transmission is working fine. Will it last? I have no idea, but for the cost I'm not going to replace it because everyone thinks I should. I do respect and take in what you have to say but you don't have to be so crude about it.

 

I am one who has favored 2400 stall for a stock cam motor but many feel higher stalls are what they like.

If the donor transmission does not have a shift kit, might consider a Transgo kit for it. You can set shift pressure with "washers" from 1-3 with 3 being the firmist. I used 2 when I had a auto with a 2400 stall and 3:42 gears. Really like that set up with a stock 350 with just the mods I noted before. Again each person will have their own opinions.

Also if going with a higher stall TC consider a external tranny cooler, especially for stall above 2400-2500, is good to keep tranny temps down.

Another mod to the motor, if it has stock and old valve springs I would replace. If putting on 1:6 RR and you need to buy them I would also buy 7/16 ARP rocker studs and get 7/16" RR. The only additional cost for the RR swap then would be the larger studs as 3/8 or 7/16 RR cost the same

 

Thanks for the advice. I was thinking of using 1:6 RR's as that is what I have used on my other 2 cars. My main goal here is to be able to beat a 2012 Impala. From what i have heard they will run low 14's. A mild bolt on LT1 B-body will run mid 14's. I got to get a little bit of an edge! haha It sounds corny yes. My Vette and my Camaro would lay waste to that 12' Impy but i will never hear the end of it if my Caprice gets beat at the strip. I did not really want to tear into the engine at all. I know I would need new valve springs but I don't really want to take the heads off or get a new cam. I wouldn't mind a cam swap if I do in fact replace the valve springs. Might as well. I can also take the oem tranny cooler from my buddies 9C1. Any idea of a good cam that has none to very little lope that will give me a nice bump in torque and Hp?

 

the b-body LT1 has iron heads with pressed in studs and swapping to 7/16" studs would require removing the heads for machining to accomodate screwin studs. Really not worth the effort when the guides will limit you to fairly low lift anyway or require more machining to resolve that as well.

Might want to question even more of the advise you get from that individual.

Heads do not need to be removed for springs.

I have experience with modern quality 9.5" converters and basically anyone is going to be happy driving a 2800-3200 and they will NOT have heat issues. The b-body external tranny cooler is so BAD the 4L60E rebuild manuals that cover all 4L60Es actually specifically point out how the b-body cooler is poorly located, it is behind the bumper WAY out in front of the condensor so it does not get proper airflow. It can be sufficient since as I said the modern converters do not throw heat the way people assume they do, but no way in hell I would specifically seek to add the b-body cooler, I run a smallish aftermarket cooler mounted low against the condensor and actually have to block it once the temp is down in the 40s or the tranny wont completely warm up.

The stock b-body converter is 1400 stall, even the trucks of that timeframe were higher stall.

Stall and gears are some of the most solid bolton mods one can do to an A4. If you have a civi L99 car though the only concern with an LT1 would be if you have a 7.5" axle you will break it if you ever get traction, it would not be worth putting gears in, at that maybe consider the axle from the 9C1, as it is 8.5" and 3.08 gears where a civi L99 car is most likely 7.5" and 2.93 gears. Big strength upgrade and minor gearing upgrade but really I would strongly recommend 3.42s for a highway car and 3.73s for city car or one you want to take to the track a lot. 3.42s were an option on the TBI cars so it is not like they are atall aggressive. At one point my car was an over 20K mile per year daily drive and I had 2800stal and 3.42s in it and it was perfect, did it for awhile with a ZZ4 cam too. Actually had a local f-body guy in the car one day windows down through town and he started telling me how a stall would be nice for the car, I told him to hold that thought till we got to the edge of town and then gave a demonstration. Point being a quality 9.5" and 3.42s is so mild a lot of folks with mistake it for stock at low throttles. At the same time though it makes the car feel much lighter.

Again if you have a civi L99 car you need to check which axle and if a 7.5" you need to address it just from a strength standpoint, it might work on f-bodies but a b-body is a good 400Lbs heavier and the few guys who have tried LT1s in 7.5" equipped b-bodies have had nothing but problems, one guy was dumb enough to repair carriers and gears like 4 times before he sold the car, when a $150 junkyard 8.5" axle would have been bulletproof.

 

I will reemphasize that with the 4l60E a proper stall and gears will make the car feel much more powerful.
I know youre talking B-body but the f-bodies are affected likewise. Ive had crappy Break and Mangle converters and they are a waste of time and money. Do it right and get the PROPPER converter the first time. The converter may be 800$, but it will beat changing your tranny for 1000 to 2500 later because you put a crappy heat maker in there.

 

I will have the opportunity to take the 8.5" axle out of the 9C1 i'm getting the engine and tranny out of so I will be getting rid of the peg leg 7.5". I probably won't be able to do gears but what would you recommend for a converter that won't destroy my bank account? Whats the cheapest converter you can buy that won't hurt the transmission? Thanks for all the advice so far everyone!

 

Another question.. i will be running stock manifolds into stock converters into a hooker catback. I was thinking that while the engine is out I might go with a little bit bigger cam than stock. I was going to go the route of the cc502. I feel like it has relatively minimal lope and make pretty good power. It was either that or the cc501. Will factory manifolds cripple either of those cams badly? I know everybody over exaggerates how bad the factory manifolds are but that is what i want to use. I know the old TBI/TPI manifolds are terrible but the LT manifolds can't be that bad, I know the Vette LT1 manifolds are pretty good for stock. What do you guys think? Just curious if it will hurt the performance that much if I go to a bigger cam with stock manifolds.

 

Having done a ZZ4 cam before headers I am going to tell you not to repeat my mistake.

tall gears and headers should be done before a cam, even when the cam is mild enough to drive fine without those things.

 

v8

many agree that starting from the "back end" of the car and work forward when adding mods (gears, TC). In your case you have a donor car oppertunity to harvest a LT1/tranny and now the rear end with gears (which are??) to replace the L99

now ? about adding a cam, fine. A mild cam will help power/TQ but any cam will perform better with headers/Cat back, TC & gears. Will it still be an improvement without the downstream mods, yes.

Back to the cam, whatever one you pick you really need to replace the valve springs. "If" pulling the heads than consider sending them out for valve lap. you can also have the pressed in studs pulled and drilled for threads to upgrade to 7/16" studs but more important is to replace valve springs & seals with the 3/8" pressed in studs. Just watch what your lift #'s will be if going 1:6 RR and a cam with higher lift. Some put in Crane 227 cam with iron heads years ago with 1:6 RR and experienced the exhaust valve RR stud pulling out. Some did a 1:6 intake, 1:5 ex to get around that with the 227 cam. while others had no problems...or did not report them.

will a cam work with stock manifolds, yes but understand "supporting mods" like headers, cat back all allow the cam to make its peak power

Torque converters, many like Edge or Yank. when I had a auto I went with a HUGHES 2400 & 3:42. later a Vigalante 9.5" 2800 and 3:73 which I did not like on the street but track times were slightly better. It all comes down to what "you" want/like in terms of TC. 9.5" or standard size and what stall. FWIW the Hughes was a decent $

once you get into these mods, a good tune will make or break the performance improvements and driveability

 

I want to keep this car relatively quiet and every car I've ever had that had headers had been a droning nightmare. This B-body is my DD when I don't drive the truck but it gets better mileage than the truck by far. Plus I didn't really want to spend the money on headers b/c from what I have seen the shorties give issues in the LT engine bay.(Too much heat) and i don't want to go longtube b/c I have never seen a reasonably priced set that are direct bolt up. I don't want to piece this system together. I know everyone says to do headers first but if I ran stock manifolds I planned on opening them up a little bit. i know they won't flow like a header but I just want that ease of installation. Are LT manifolds really that bad?

 

v8

nothing wrong with using stock manifolds. many of us get hung up on what makes max power from a particular mod.

a cam with good low end TQ even with stock stall and gears is going to be a noticeable improvement in DD conditions. even if you keep the stamped stock 1:5 rockers, change valve springs & seals. add a 2400+ stall and some gears and a cam motor or stock motor will have mor "get up" to it. It all comes down to what your needs and $ are.

you are swaping motors so a small cam swap and springs are a good idea. you will need a tune for the new cam.

SLP shortys if they can be found, bolt in. edelbrock shortys are available, are CARB legal but do require you to cut the elbow off the front of the PS CAT and weld on the elbow flange that comes with that kit. both shortys offer some HP/tq improvement but not as much as mid length headers like Dan's Tri-y's

I wouldn't really spend any time trying to open up or improve stock manifolds. It would be hard to measure, if any, power improvement.

 

Pacesetter shorties can be had for cheap and bolts to the factory y pipe