Prodigious

What would it take to get an L98 car into the twelves? I don't know what my car runs yet as my track doesn't open until November, but I want to know so that I can get the car as close to my goal as I can.

So far I have a .030 overbore, 1.50 roller rockers, a cam (previous owner didn't know the specs and I honestly don't know how I would go about checking them without pulling the cam out), hooker long tube headers with 1-3/4" primaries, and a 3" single exhaust with no muffler and no cat. The trans also has a shift kit. Otherwise everything is stock.

92g92

For starters, the 1.50 rockers are no improvement over the stock ratio. Long tube, 1.75 inch headers and 3 inch exhaust are plenty to put a healthy running L98 in the 13's. The cam is a mystery, so who knows. It's unlikely the previous owner managed to take a step backward with the cam, considering the stock cam's already wienie specs; that being said, many people don't correctly match the cam to the rest of the engine. With a proper cam in your set up, something like a hot cam or ZZ4, you know something kind of mildish for a mostly stock engine, could put you in the twelves with good tires and nothing extra in the car like subs or the like. I don't know what shift kit entails. If that's a properly matched stall converter, you have a much better chance at 12's. If it's firmer shifts or adjusted shift points due to the cam, that's less of an effect but still a bonus. Also, I can't imagine the ugly, horrendous auditory assault your car must inflict upon people without a muffler.

Orr89RocZ

iTrader: (20)

Start with converter 2800 ish stall, sticky tire and swap intake to something like a stealth ram or pro flo xt

Prodigious

I would prefer not to swap cams at this point in time, because this is my only car at the moment, so pulling the motor to change cams isn't really an option I can use. The transmission has the factory torque converter unfortunately, but the shift kit really just provides firmer shifts. And the exhaust has either a resonator in it or a muffler of some type, I honestly have no clue what it is, but it isn't just totally straight piped from the headers. It's pretty loud, but it's not ungodly loud like my first post made it sound. Definitely nice and throaty though, but idling it's more of a thumper than anything.

Also, right now I'm running BFG G-Force tires, should I get stickier tires than that? Like a set of slicks for the track? A 2800 stall and gears were mods that I was thinking would be the most significant right off the bat, but I don't know what ratio gears to get. Anything lower than the crappy 2.73s would surely benefit though. And for the intake, I was actually hoping to keep the long tube runner setup because I like the look of it, I like the low end torque, and I like that it's different, but if the twelves or better are not achievable with long tube runners, even if it's all aftermarket stuff, then I would have no problem with swapping intakes.

Thank you both for your help so far.

Orr89RocZ

iTrader: (20)

Yes a drag tire like a slick or preferably a drag radial on stock wheels. If you cant buy drag wheels and skinnies

2800stall, 3.23-3.42 gear, and good tires will give great gains for the buck. Next is getting rid of stock tpi for a shorter runner intake system and retuning

Street Lethal

iTrader: (16)

That is very telling right there. I would go with nitrous, as gas mileage stays the same, you won't rush to meet a deadline to get an installation done, and 12's are essentially a push of a button away depending on how much of hit you go with. Drag radials help tremendously as well. Just my two cents...

TTOP350

iTrader: (8)

I did this back in the early 90s with my 89 Formula 350 and I drove it daily.
You should be able to go 13s with it fairly stock.
12s will cost some bux to do but you will have to change some parts. (I ended up in the 11.70 range)

Prodigious

Okay, so drag radials, 2800 stall, and 3.42 gears are sounding pretty good so far. As for nitrous, that was going to be my sort of last resort just in case I don't make it into the 12s with the other mods haha. Kind of a cure all. Gas mileage isn't really a concern for me, as long as it's not single digits I'm happy.

And a stealth ram also seems like a really nice budget oriented option after the drag radials, stall, and gears.

Orr89RocZ

iTrader: (20)

Thats what i did and squeeked 12.9's. 1.6 rockers and underdrive pullies. Every lil bit helps

Prodigious

This makes me curious as to what additional mods it would take to get into the lower 12s. Heads and cam? Or just suspension work?

Who knows, maybe my mystery cam is better than you guys think

Orr89RocZ

iTrader: (20)

Def atleast a cam and tune. Heads cam easily

Prodigious

Yeah, I figured. Would suspension work actually help times at all though? Or is that really only good for handling?

Orr89RocZ

iTrader: (20)

Some things like lca angle and good shocks can help. I like adjustable shocks. For drag set them light in front and medium stiff rear. Street set it medium stiff all around.

For what you are trying to do i dont think the major suspension overall stuff is gonna help 60's that much. Subframe connectors would help. You wont need a torque arm. It all is nice but for lower power levels stock suspension isnt bad

Tibo

iTrader: (15)

Go ahead and spend the next week reading over Traxion's posts. He left Thirdgen a few years ago so you can't message him. From what I remember he had hooker super long tubes, full 3" exhaust, can in the high 240 or low 250 duration, AFR heads, mini ram, drag radials, at least a 2800 stal. There is a video of him going 11's. Everything else on car was stock, no weight reduction.

Prodigious

Old thread guys, but I finally got to run the Z down the track today, and with the mods I listed in the original post, it ran a 14.64 as it's best time

I feel like the cause was the mystery cam mostly, I think one of the PO's may have given it too much cam for TPI. Another issue was traction, on my BFG G-force street tires I had to launch fairly soft or else it wouldn't hook at all. That's all I can really think of though, because I figured a good running L98 with headers and exhaust should at least be low 14s.

TTOP350

iTrader: (8)

Well, time to get cracking on getting it dialed in. Very rarely does everything just fall into place and work correctly.
The stock intake is a major restriction when you start making power.
What heads are on this motor? TPI or TBI?

Prodigious

TPI heads are on the car, and yeah, I'm thinking its a combination of the intake and traction issues because of using street tires. I just don't understand why I'm running essentially stock L98 times when I have headers and full exhaust done as well. Did the mystery cam really throw it off that much? Either way I was planning on installing aftermarket TPI stuff as soon as I get the money, because I think I want to keep the LTR setup.

The waiting list right now, in order of what I plan to do first to last: Mickey Thompson ET Streets, 3.42 gears, full aftermarket TPI

Tibo

iTrader: (15)

You'll probably need to "freshen up" the rear end and get some new or lightly used tires for sure. The TPI can go into the 12 sec range (N/A) but it will be far cheaper and easier to tune if you ditch it and buy a stealth ram/converted single plane/mini ram. All of the stock heads that these cars came with will need to be ditched for aftermarket aluminums or Vortec. Unfortunately the intake and cylinder heads will easily run you $1000. Then you will need to get a good cam, then you will need to buy and learn a way to reprogram the stock ecm. If you are extremely lucky you may be able to buy all of these parts used for $1500.

If you plan on keeping the car for years to come and will have the ability space and time wise I would recommend to just buy some good tires and rebuild the rear end with some 3.42 gears and drive it and have fun. Put the money toward the O-so-popular 5.3 turbo LS swap. Many auto yards will sell the engine and tranny together for $500, there are thousands of people who will do or sell you a ready to go turbo 5.3 ecm. Decent Ebay turbo kits can be had for "cheap" now too.

I have thousands in my AFR headed 383 and it can run high 11s, but there are guys I meet, read about and YouTube watch that run the same times with Junk Yard bought 5.3 truck engines and ebay turbos for a grand total.

Prodigious

Tires for sure, but the posi still works good and nothing in my rear end leaks, so I'm pretty sure it just needs new gears and some fresh fluid, and throw a TA cover on there for sure too. I definitely don't have the space or time to do an LS swap, so I think after that I'll be confined to the stealth ram or aftermarket TPI and then some newer heads later. I think the cam already in the car would be good for really any intake besides TPI, so it may be okay to stay. Would have to see how it does after putting a new intake on it.

Orr89RocZ

iTrader: (20)

What was the mph

If you had traction issues then no doubt it wont run as good as stockish L98's lol

Prodigious

Mph had a best of 92, but my fastest run was only 89 mph. Traction issues were only on hard launches, so I had to kinda roll slowly onto the throttle at first. Probably only launched at like 1500 tbh haha

Orr89RocZ

iTrader: (20)

That tells the story. 92 mph is way low for a good running L98. That car needs logged and tune looked into

Prodigious

So you think I should get the tune looked into before doing any other mods?

Maybe I have a bad sensor that is throwing the tune off. Could that be possible? I know I had to change the TPS a while ago, and I'm pretty sure I have a bad oil pressure sender, not that that would affect anything but still. Maybe the others are on their way out too.

Orr89RocZ

iTrader: (20)

You dont know what cams in it and no idea what the tune is like

Tibo

iTrader: (15)

Check into buying the EBL from dynamic efi aka rbob's creation. I went with MegaSquirt but nearly every other member that stays sbc gets the ebl and has great things to say about it.

Prodigious

So definitely focus on the tune as a #1 priority I take it guys. I think I'll have someone check the tune out first, and then later after getting it tuned right and adding more parts I think I'll splurge on the ebl. The ebl p4 system is the one that works the easiest with a TPI car right? That's what the website seems to say.

Prodigious

I apologize for the double post, but what results would I really be expecting with a tune? And would a bad tune really throw off my quarter mile times and trap speeds by that much, yet the car would still run reliably? Starts right up unless I turn it off and then right back on, and it doesn't misfire or surge or anything. I'm 90% sure it runs rich though as I can smell the gas if I rev it with the door open. But it runs and drives fine, that's why I don't completely understand how the tune could be that far off. Also, the car was a factory LB9 car that supposedly had a rebuilt 350 bored .030 over and given a replacement cam swapped into it. I didn't even know it was a factory 305 car until I looked at the vin. Would running a rebuilt l98 on a 305 chip cause this type of thing? If so that may be what I'm experiencing.

I apologize for my ignorance to this subject, that is why I'm here to learn.

Tibo

iTrader: (15)

There is a very technical response that I don't have time to write up right now, but a short response would be that even a throttle body change would need a change to the tune. A camshaft changes the air usage entirely. It's entirely possible to up the fuel pressure and change the timing and the car can still drive OK but if that can has been changed you need a tune period.

Orr89RocZ

iTrader: (20)

As said above, it very well could be far enough off to make a significant difference, esp if its a 350 on a 305 chip! It may not be rich and rather lean as you can have gas smell when real lean as well

Prodigious

Okay, I think I somewhat understand now, thank you guys and I will look into a tune asap.

zya5point0

iTrader: (4)

OK, I know this is an older post, but, if the OP is still looking, here's a little tidbit... My old 86 Z, stock 305, superram runners and plenum with only a flowmaster cat-back went from 15.6 to 15 flat after I went from 2.73 to 3.73 and put an auburn posi in

Prodigious

Car hasn't been to the track since then as I've got more stuff on my to-do list before running it again but I think I found out the problem with why it was running so slow. Timing was way retarded and after advancing it to about 12 degrees btdc it picked up a tremendous amount of top end. I also had my rear end rebuilt with a trutrac posi and 3.42 gears and that helped a lot too because my stock posi was pretty worn out and would do one wheel peels a lot, and 2.73 gears are obviously just garbage for anything performance oriented. I have some new Bosch d3 injectors and an AFPR to put in whenever I finally get around to tearing my intake apart. I also had sfc's and LCARBs welded in. Car feels a hell of a lot better than it did back in October in just about every way imaginable. Still got a lot of work though, I would like to at least get my injectors and AFPR in, and get an extra set of wheels I can mount some et streets to before I hit the track again and see what she does. I don't want to disappoint myself by making a prediction, but I'm kinda expecting 13.7-13.8 at least next time I hit the track. My butt dyno probably isn't that accurate though and I could very well be slower.

cuisinartvette

edit, re read

at least you know your baseline dont worry about your times
it can take many changes and passes to get there be patient.
Youd be surprised how many "11 sec 500hp" cars are claimed and they have never even be driven around the block. Thats the web for ya
Least youre learning more about your car and having fun...and no tickets!

John455cid

I would put 3:73 gear in the rearend . It Will definitely put you in the 12s. I have a 72 grand prix 463 cid 400 turbo trans 3:73 gears . Runs 12:40s in the quarter mile. all day !! Cam is 500 lift 290 duration. 1.6 rockers.

MikeJR1991

I had a 1991 camaro z28 back in 1993. It was a 5.7 G92 car that ran 13.0 @ 107mph 4 times in a row! With a higher stall converter it would have easily been in the mid 12’s with that mph. The car weighed 3380lbs (Driver approx 185 lbs)

Here is what I did to it...

All the little tricks, hypertech chip, quarters under the FPR, K&N filters w/ homemade ram air, TB air foil, MAC under drive pulleys, SLP 1 5/8 headers, hollowed out cats, SLP two into one muffler, 3.42 gears, shift kit w/stock converter, 1.6 roller rockers, zz9 camshaft & Accell super ram intake.
Everything else was stock. Stock heads, stock torque converter, full emissions, EGR, etc.

Swiftygp

I have an upper plenum and runners from the Lingenfelter SuperRam, a stock L98 throttle body that I had bored to 52mm, and a Hot Cam for sale for $800. That should get you pretty close. I'll throw in a spare stock L98 lower intake manifold and fuel rail I'll throw in as well. My phone number is 703-618-9640. I won't answer if I don't recognize the number so leave a message if you're interested.