I am looking to rebuild my L98 in my 91 bird. I have been looking into doing the LT1 swap but i think for my money i could just get this motor rebuilt and have more power for less money. I want to know what would be a good combo to put in this tired TPI to get some decent gains. I dont think i need to go with fogred internals, i dont have enough money to go that crazy on HPs hehe. Just what cam, heads, pistons i should look at and purchase. Ill be happy with a good 13 second car for now since im just out of college Thanks for the help ill try and answer any questions i can.

 

hyperuetectic(spell check this...) pistons, decent 210-220 duration(@ .050) 500 ish lift cam and ported stock heads w/ aftermarket base, runners, ported plenum, and full exhaust will get you low 13's. I personally won't have rods resized because you can buy aftermarket for slightly more than the cost of resizing. - have the crank checked, if it needs turned you can buy a new cast crank for around 150-200 so, once again, new may be better than machine work. - yes you can rebuild and have more power for less dolar than an LT1 swap. - if you don't have to meet emissions, look into HSR intake.

 

Yeah thats a problem cause i do have emissions requirements where i am at. So basically a mild cam, maybe a ZZ4 cam or LT4 hotcam? Stock heads ported, instead of new heads will be much cheaper. What aftermarket intake base would be a good fit? Im sure while its off i could have whomever i get to port the heads to port the plenum and runners to match. Learning experience hehe.

 

you can do the porting yourself if you have half a place to work. - do a search on here about porting L98 heads. you can gain a lot for cheap. - uuugghhh...I hate emissions. - mostly it would depend on your finances. For a big improvement, look at either the Super Ram(accel) or the FIRST system. I personally like the FIRST set-up, but it takes a little knowledge/ingenuity to set it up(do a search). - if you're sticking w/ a less money route, do a search on aftermarket base/runners. you'll find more info than you'll ever need.

 

Ok thanks ill do that. I have some tools from being a tech at a nissian shop but nothing really to port with besides a dremil.

 

Why do you want to pull the motor right now? Is it leaking and all worn out? Think about what you want a little more and we can find some better alternatives than a full rebuild. If all you want is 13's then start with exhaust, cai, tune, and smaller bolt-ons. Spend your money wisely though. Only buy parts that will work for you later on down the road. Nitrous is also a great alternative. My 85 305 tpi almost hits 13's and that was with an extremely worn camshaft. Barely beat a almost stock lt1 and could only turn 5,000 rpms. I would say with emissions to run a 3 inch y-pipe, and have two high flow cats on it.

 

Well this is going to be a ongoing project that i would like to piece together the next couple months then bring the car down and rebuild it. The car has some leaks, nothing major, but it is smoking some on start up, so i think the seals might be on their last leg. As of now i am going to be putting headers on the car and rebuilding the suspension. This should be done this friday, then i will be saving up for some new go fast parts. I just wanted a idea on which direction to go with the heads and intake.. Sounds like a good cost effective way is to port the heads, aftermarket base, and a new cam. Thanks for the help guys.

 

Okay sounds like a good plan. Preventitive is always a safe way with these cars. Porting and polishing may get good gains, but have you read the lt1 head swap article? I would recomend porting and polishing a set of lt1 heads and intake, or moving to a set of aluminum l-98 corvette heads. I do not know how much money is a factor for this sounds like its tight, but you have some. LT1 swap the engine and keep everything tpi is also another good way to go. I can not say much good comes with opti-spark system. The lt1 block has many more advantages than your l-98 and can still put a distributer on top.

Just thoughts,
Greg

 

yeah i looked into a LT1 swap awhile ago and just to get the motor and swap it in was about the amount of money i was looking to spend. I was hoping to get some more horsepower than 300 out of the motor once i was done. Its still a good idea and im not ruling it out by any means. I have not read the LT1 head swap artical i will have to search for that and read it, sounds like a good idea.

 

Its a sticky not very hard to find. The reason I would sujjest and lt1 motor swap is the price is good and the rotating assembly is much better than a l-98. Nitrous many people do not like this word, but its cheap, fast, and reliable if your car is running right. Your car in spurts would love up to 150 shot. Much more and you start getting into problems, and anyless really isn't worth the bother.

 

think about the difference between a Lt1 and a L98. get the vortec alum. heads. they do not cost all that much and a machine shop should be able to make them work for your car and put gasket match port job to your heads and intake.

I do not know how worn out your roller set-up is. Mine was done and I put in the comp cams computer controlled 262 series cam and it is sweet. Use your dremell to port the upper penuim you should be able to get the down low on how to do this using the search. Do not go over 10:1 comp if you want to use pump gas.

if you can just freshin up the bottom with rings and bearings then so be it.

Where you will gian all kinds of power is more fuel and better spark. injectors 24lbs and a nice coil with high performance cap rotors wires and dope plugs are the ticket.

Get a new prom burn and watch the R's

 

10:1 compression on pump. Pump gas can safely take 11:1 and if you are gutsy 12.5:1 is the most pump gas can handle.

 

maybe you guys can help me out with this so i dont have to make a new thread. With the car bone stock i could only get it to run a 15.1 in the 1/4 at 91mph. Thats way low for a 350TPI i know. I just dont know where the problem is. I have new plugs wires cap rotor, the car idols fine. Does smell kinda like it might be running rich but the plugs after 3k on em still look ok. Whats the best way to find out whats going on? should i take it to a dyno or have someone who can program the EPROM check itout?

 

These cars have weak cams, many wear down and never ge replaced, and people wonder why there car always seems to be a little slower. Not saying that is the problem, but I am just giving you another idea of what to look for. Vacuum leaks are also causes for lost power, do you have all good lines? TPS setting? IAC still good? Coolant temp sensors not cooroded away? Knock sensor works? EGR plugged? The reeal big question whats your fuel psi look like and what do your fuel rails and injectors look like? If you check for all of these problems you have a good idea of what is holding your car back.

 

thanks for the ideas ill look at it

Vaccum lines seem to be alright, no major leaks that i have noticed, i have replaced a couple already.
How do i check the TPS setting? And im going to look up what IAC is so i know what your talking about. Coolant sensor seems to be working fine and doesnt look too bad. EGR valve i had to replace. Knock sensor is brand new. And i have a brand new fuel pump in it also.

 

Hey Matt, if you ever need to work on your car let me know. In the next 6 months I would like to tear into my motor as well. You doing anything to it in the next few weeks?

 

Hmm in the next few weeks im going to attempt to figure out the whole datalogging thing and try to understand it. Then i might get into tuning if i can figure ot how to read the datalogs. Figured i would start out with this before i got into pulling th motor apart.

 

I also agree on the overhaul if possible thing. If your bore isn't overly worn and everything is a decent shape, new rings/bearings/gaskets may be a good way to go. - You stated rebuilding the suspension. As in new balljoints/tie rods/bushings, or are we talking sub-frames/lca's/tube torque arm? The later would be a great place to start towards your goal. Make the car handle the power before you put the power in - TRUE preventative maintenance...