firebirdjones

Well I finally have some results after the long wait over winter. For those that don't remember, I have an 88 Iroc L-98 350,,,automatic with 2.77 gears. It started as a bone stocker with 50,000 miles on it when I purchased the car. I ran a best of 14.60 at 94 mph at that time with only the base timing bumped to 8 degrees. Over winter I installed some hooker shorty headers with hooker Y-pipe, removed the cat, and installed Edelbrocks cat back exhaust system. I needed to do valve seals as well, so this was a good time to step up to 1.6 roller rockers. One other mod I did was an adjustable fuel pressure regulator. Mainly because I do not have the required equipment to tune the computer and change fuel and timing curves and I feared the car would be lean with the exhaust mods, so I bumped fuel pressure up from the stock 44 lbs. to 48 lbs. for starters. This will be a temporary mod until I get the programs to tune this thing properly.
Thats it,,,the rest of the car is untouched and still using *** awfull 2.77 gears lol. I drove to the track and right off the street I ran 14.10 at 98 mph with a 2.18 sixty,,,spinning a little coming out. I am running on stock rubber as well so no water bunouts necessary, just a nice long dry burnout to clean the tires off. I wanted to try a bump in fuel pressure to see what happens and I let the car cool for 15 minutes. Next pass was 14.11 at 99 mph with a tire spinning 2.21 sixty. I decided to leave the fuel pressure at 50 lbs. and concentrate on the 60 for a couple passes. After a short cool down I heated the tires a little more this time with a harder dry burnout. I came out of the hole about half pedal and it stuck so to the floor it went,,,I was rewarded with a 13.92 at 99.59 mph with a 2.10 sixty. I let the car cool again and thought I would try a little harder on launch to see if I could find the limit,,,,,well I found it,,,,,next pass fish tailed through all of first gear but still ran a 2.20 sixty and a 14.05 at 99 mph again. A little easier on the launch with the next pass got me another 13.95 at 99 mph. It seemed to like 50 lbs of fuel pressure as it consistently ran 1 mph faster and the ET just depended on the first sixty feet of course. I left the base timing at 8 degrees since that is where it ran best the last time out. I was surprised to get the car into the 13's with only exhaust and rocker arms and fuel pressure. I haven't even messed with the intake track yet. And I am doing it with 2.77's,,,,,
A complete rearend is in the works with more gear, some intake runners and a ported plenum, a computer program to play with fuel and timing curves so I can put the base timing back to 6 degrees and the fuel pressure back to 44 lbs. The car is getting to the point where some sticky rubber will be needed as well for more consistent 60 foot times. I think with a few more things that I have planned it may run deep into the 13's and break 100 mph,,,not too shabby for an old tuned port motor thats never been opened up Here is a pic to go along with it. Larry.

firebirdjones

Since I am in a picture mood,,,does anyone want to see some pics of my other junk, although not exactly 3rd gen related,, I have an 11 second chevelle, and my wife drives a jeep Scrambler with a 96 Corvette LT-1 drivetrain,,,plus some other junk,,,,I just don't want to affend the administrators,,,Larry.

Tobias05

better than me bro, congrats! ran a 14.9@96 today, no traction either.

89IrocZ350TPI

Good times for a near stock L98. My L98 has nearly full bolt ons, and runs 13.5 at 99. I think I need some better traction though. If you are looking at gears id go with something in the 3.23-3.45 range. That way you will keep the TPI in its powerband.

urbanhunter44

iTrader: (3)

Headers, catback and an FPR isn't stock??

firebirdjones

Read carefully,,,,,I said nearly stock,,,,I posted my stock time of 14.60,,,,exhaust is hardly considered much of a mod anymore when you are talking about a 20 year old car,,,,how many are left still wearing their factory issued systems? I would suspect not many,,,,mine was an exception considering it's been stored in a climate controlled garage and only had 50,000 miles, I was able to remove the system and save it. In my opinion an exhuast and FPR is nearly stock considering all the mods that are possible on these things,,,and I think most would agree. Hell I still have the stock chip, (tune) on it even.
Besides this thread was meant to be informative, there was alot of talk on here about whether an L98 would break into the 13's without getting into the engine. Since Car Craft or one of those mags seemed to have alot of trouble doing it. I decided to take my bone stocker and do the same thing with minimal bolt ons and see just how quick it would go,,,,as you can see with very little work it's already there,,,and I have more bolt on's to try.
I seem to remember the mag even spraying the car with a 100 shot and barely cracking high 12's after a correction factor I believe there is another 6-7 tenths left in this car with some other bolt ons, gears, and tuning. Only time will tell.
Oh ya,,,89 Iroc,,,,I already have 3.23's I am setting up in another 7.5 rear along with a new posi and new axles. I picked the 3.23's mainly for the exact reason you mentioned,,,with this stock intake setup it's out of breath at 5,000 rpms, no need to spin it higher. Thanks for the heads up though. Larry.

Orr89RocZ

iTrader: (20)

sounds good

L98 cars dont need a whole lot of mods to get into 13's.

your car sounds like mine. i did headers/catback, 2800 stall with gutted airbox. 2.77 gears stock... also had some adjustable shocks and Prokit springs. car was a handler... but i took it to the strip and got 13.89 at 96.6 mph on street tire rubber. 1.895 60 foot

after that, i did 3.27 swap and it didnt pick up ET yet, but matched my 60 foots with 1.88 and 1.93's. but i picked up 3 mph traps. 3.27's wakes up 2nd gear

firebirdjones

That is good info to know. Glad to hear the gear was worth something,,,,thats about the same gear jump I am making,,,except I am scrapping the Aussie rear and found a GM 7.5 out of an earlier model, bought all new parts, gears, posi, axles, setup kit, etc....just not finished with it yet.
Glad to hear of another 3rd gen running similar times,,,I was the only 3rd gen at the track,,,all other F-bodies were 93 and up. New times will be coming soon,,,Larry.

1990GTA

I need some opinions on what could be my problem. My car comes out of the hole on what should be a mid to low 13 second pass and seems to crap out at about half track. Maybe I need to turn up the fuel pressure?, I made 2 passes Friday night at about 45 psi.. I was going to increase it on the next pass, but I was not able to make another run. The car is a 1990 GTA, 5.7 TPI,3.23 gears, fresh rebuild on tranny with 2200 stall, Crane 2032 powermax cam,24# injectors,AFPR,LT headers,2.5 duals. Here are the numbers from a couple time slips running slicks at around 17 psi..

60' 1.951 60' 1.891
330' 5.846 330' 5.718
1/8 9.104 1/8 8.952
mph 76.47 mph 75.77
1000 11.944 1000 11.744
1/4 14.309 1/4 14.084
mph 95.32 mph 95.80

1990GTA

The post above was made by me the other day. I copy pasted it here because the times you guys are running is what I am talking about, your 60' times are almost identical to mine, but I am still running 14's.

firebirdjones

One thing I noticed is you are in Orlando which is nearly sea level,,,,you should be running slightly quicker times than most with a mild combo as long as you have good air and good track conditions. Our density altitude here where I live is generally around 2-3,000 feet depending on temp, not very good most of the time.
The other thing I noticed is you are running long tube headers with a real dual exhaust system? This is even more free flowing than what I have. Plus you have a camshaft change? So you have been inside the motor as well.
I see your 60 foot times are better than mine,,,I would account that to your slightly looser converter, a little more gear and some sticky rubber,,,all of which I don't have at the moment. So why is your car not running the numbers I am? I can only think of 2 reasons off the top of my head.
Mileage? Is the short block worn, any blowby? My car only has 65,000 currently and is very tight,,,so I have an advantage since these cars are approaching 20 years old now,,,most are wore out so I would expect a car with 100,000 or more to be 3-4 tenths slower just because of normal wear and tear.
The other thing that comes to mind you already mentioned so I think you are thinking the same as me. First with your exhaust which should flow better than mine,,,,I think your fuel pressure is too low. Your car is bound to be running on the lean side, especially at your altitude. I assume you have a stock computer tune? Mine is a stock tune as well. I was afraid of it running lean which is why the AFPR went on the car,,,,my car had 44 lbs. of fuel pressure stock, which is where I started when I was just driving the car on the street. It had a lean stumble right off idle which did not surprise me, especially when it was cold. I bumped the fuel pressure up to 48 lbs. (if you make a change make a big one I always say) and right off the bat the stumble was gone and throttle response was very crisp,,,so I left it there and drove it that way until I could make it to the track last weekend. Since it surprised me on the first pass, I decided to find a happy spot for the fuel pressure,,,,it turned out I was not too far off anyway,,,,50 lbs. gave me my best mph. It seems the car wants alot of fuel,,,I wanted to try more but ran out of time. This just tells me that I need to do some computer tuning and play with the fuel tables so I can return fuel pressure back to normal. With this in mind I would think your car may respond similar to mine, maybe more so with your camshaft change and better exhaust.
This is just my opinion, but since you have the regulator it is definately worth playing with at the track for sure. With your short time of 1.89 your car shouldn't have any trouble getting into the 13's,,,,just gotta get the mph up a little. Give it a shot and report back,,,,it sure is fun to keep trying though. Larry.

urbanhunter44

iTrader: (3)

I misread your post, my bad.

imo L98s don't need hardly anything to break 13s. I'll bet you get a 91/92 SD G92 L98 and stick some tires on it and it'll hit 13s. Still won't trap worth a damn though lol

firebirdjones

I guess it's possible without much work,,my L98 was pretty far from 13's when stock though,,,running 14.60's,,,tires wouldn't have got me there as it was such a turd you could stab it and go,,,60 foot times were very consistent but it needed some help.
I was surprised that with very little done it picked up as much as it did, and I am still doing it on stock rubber, traction is becoming an issue and there is probably 2-3 tenths more left in the car with just adding sticky rubber. I would have had some on there but what I am running on the other cars does not fit the Iroc Probably a 13.70 in the car with good tires. Oh well,,,I want to try some other bolt ons anyway. I can't leave anything alone Larry.

Orr89RocZ

iTrader: (20)

your having the same problem i'm having... i get out the hole with a 1.93 60 foot with the new 3.27 gears i have. 1/8 mile was 8.88-9.9x's at 80mph. 1/4 mile was 13.98-14.1's at 100mph. one run i had 1.88 60 foot and hit 8.88 1/8 and 13.99 1/4 mile. i'm trapping 100mph and have good 60's but the car isnt running any good ET's. i should be 13.7's at least. 1.89 60 foot with my old 2.77 gears gave me 8.80 1/8 and 13.89 1/4 at 96.6

and i dont have anywhere near the mods u have. just headers/catback/airbox mod. some suspension with 2800 stall.

i'd say up the fuel pressure cuz with that exhaust and cam, i bet ur abit lean up top

89IrocZ350TPI

Sometime the numbers just dont show up at the track, even though the car feels quicker on the street.

1990GTA

The car is almost out of control on the street, I can nail the gas at about 20 mph and it just roasts the tires. I will turn up the fuel pressure the next time I go to the track and hopefully that is what the problem is, I will post the results.

quickL98

iTrader: (2)

Congrats man, good runner huh?

1992 Zee

My 92' 350 Z-28 ran 14.22 with only a SLP chip, air box sheilds removed and stock exhaust back in 1993.

1MeanZ

iTrader: (9)

Why is your "full bolt on L98" trapping the same as my wee little 305? I am just curious.....

firebirdjones

I didn't mean to start a war here. I just know getting a nearly stock tuned port car into the 13's has had alot of controversy, and when I did it with very little work I thought I would share.
1meanZ, you have a nice running car for a 305, but according to your sig you have a ton of money and work involved in that timeslip, including a head swap, camshaft, etc...I don't want to go that far with mine, but I was impressed with the car with what little I have done, with only headers, cat back exhaust, 1.6 roller rockers, and adjustable fuel pressure, I cracked the 13's @ 99 mph and did it with 2.77 gears and a slush box, granted it's a 350 but I hardly broke a sweat with the bolt ons. Now I am doing gears, sticky tires for more consistent 60 foot times so I can compare the bolt ons fairly, some chip tuning, intake runners and some port work on the plenum, and then go from there depending on where the car runs. I don't think low 13's are out of the question Only time will tell. Hope everyone had a great Easter weekend,,,,Larry.

87TPI350KID

With 3.27s 2nd gear takes forever even still, can't imagine 2.7x gears

With a stall, suspension work, gears and maybe some induction mods, you should run some lower 13 runs. Keep us updated.

1MeanZ

iTrader: (9)

[QUOTE=firebirdjones]
1meanZ, you have a nice running car for a 305, but according to your sig you have a ton of money and work involved in that timeslip, including a head swap, camshaft, etc...QUOTE]


Anyone on here running bottom 14s with an L98 gets my respect, because every car in my area with a 350 runs high 14s. I have embarassed countless modified and stock carb'd and injected 350s. I dont know what it is around here but the thirdgens are all turds.

That being said, I do not have that much money in my car as was stated above. I spent a ton swapping in the TKO600, but now I am running a 2.1 60ft when I used to run 1.9s with my auto, so not much 1/4 mile help there... I have the same amount of money in my exhaust as everyone else on here, I have a flat tappet cam and you all L98 guys have a roller cam, and I only spend $600 for the heads. the intake is just stock stuff ported with a stock chip. Yah I have a head and cam swap but we all know the peanut cam sucks so I had to get that out, and AL L98 heads are pretty cheap. The only parts I have that you all dont is the heads, and they were not that expensive or hard to swap...

To wrap up all my comments, I simply want to state that small block chevy's respond well to mods regardless of their original displacment, hence their popularity. If you want a bolt on street performer, either the 305 or 350 are suitable candidates. I am merely trying to point out that similarly modded 305s will perform similar to 350s with similar mods.

P.S. there are many iron headed LB9s running my times or better. Fewer are at my trap speed though.

neagan

iTrader: (7)

Hi Larry! I know this is an older post, but I've got a couple questions for you...
Right now I've got my 99 IROC L98 in pieces as I'm updating a ton of its parts. I got mine last January with approx. 150k miles. I also have the Aussie 2.77 posi rear and the 700r4 trans. After giving mine a solid tune-up I could barely chirp the rear tires with old balding rear tyres. How good did your hot-rod run with the low 50k miles before you did any of the exhaust mods???

I'm slowly putting together parts for a new engine, had the stock intake mega-ported along with SLP runners, AFPR, full 3 inch exhaust, etc. So I"m mainly curious how low on the factory horsepower I was to start with. ( I did have PROMSforLess burn me a new chip and it would do a quick tire spin after that.)

If you've got the time, I'd love to hear what your baseline was. Hopefully you've got the new gears in and some of the other mods.
Take Care, Nitro

firebirdjones

Wow I haven't seen this post in a while. To answer your question, when my car was a bone stocker right down to the paper air filters, it ran 14.60's at 94 mph. 60 foot times were always in the 2.15 range. In this form the car liked 8 degrees of base timing. Anything more and it slowed the car down and audible detonatation could be heard.
I installed an Edelbrock cat back, removed the cat, installed hooker shorty headers with a hooker Y-pipe, K&N air filters, throttle body bypass, and an adjustable fuel pressure regulator. With all this done and the fuel pressure bumped to 48 PSI the car ran tire spinning 13.90's at 99 mph. 60 foot times varied from 2.1 to 2.3 because the car had so much more grunt with these mods it was very hard to launch consistently on stock tires. I ran a string of solid 14.0's and 2-3 passes in the 13.90's with a best of 13.92. MPH was always 99 and some change.

Yes I am doing this with the 2.77 gears. I have a 7.5 inch 10 bolt rear built with 28 spline Eaton posi, 3.42 gears, Moser axles etc.....ready to go, but have yet to get in the car. (the roller cam in my chevelle has failed ) so that has had me tied up at the moment.

Racing season is about over here so I plan on getting the Iroc ready over winter, installing the rearend, probably run some drag radials on it at that point to make my 60 foot more consistent, 3.42's will make the car even harder to launch on stock rubber. I am also starting to custom burn my own chips, and I have installed 1.6 roller rockers on the car as well.

With all this done I don't see why the car wouldn't run some easy mid 13's and probably crest the 100 mph mark. I haven't messed with the intake yet, I may port that, install larger runners and see what that does for me as well. I don't plan on getting inside the motor at this point as the car just has 65,000 miles now and runs perfectly. It will have to give me a reason to if you know what I mean.

As it sits right now the Iroc is already spanking the crap out of my 97 Z-28 LT-1 with a 6 speed and 3.42 gears. Bolt on for bolt on the cars are about equal, but for some reason the Iroc just smokes it by 3-4 car lengths. I think this Iroc is just a freak or something. Larry.

91greenbird

iTrader: (4)

this has got me to hope for 13's i dont kno what my cars problem is i launched at idle with street tires at 25psi in drive. Mods and drag times are in the signature. How should i launch it since i ran my car i removed the maf screens, grinded the egr walls down, have a fuel pressure regulator going on next week and plan to take the timing to 12 degrees.

firebirdjones

Did you run that time with the mods in your signature? If so I would say you probably have a little something going on, but still a respectable time. I think you will find quite a difference with the adjustable fuel pressure regulator. With your headers and exhaust mods it may be a little lean. I noticed right away after I did my exhaust, my car picked up a part throttle stumble, once I bumped the fuel pressure up from a stock 44 lbs. to 48 lbs. the stumble not only dissappeared, it was like a flipped a switch. My car really responded to added fuel pressure.
Your car may work with the extra timing as well, I just couldn't do it. I have heard others running 10-12 degrees base. My car just didn't like it. 8 degrees is all I could get away with.
Your 60 foot times are right on par with mine, I had stock street rubber and 2.77 gears. You will just have to play with it and see what the car likes. Every car seems to be a little different. Mine may be somewhat of a freak since I have heard of very few irocs beaking 13's with very little mods.
My LT-1 97 Z-28 is just the opposite. An engine with much more potential out of the box, better trans, more gear, and quite a few bolt ons but it won't crack the 13's at all, mid 14's are about it at about 98 mph. Yet I hear of and see many stock LT-1 cars cracking the 13's with relative ease.
Just depends on the car I guess, keep playing with it. It's fun,,,,Larry.

91greenbird

iTrader: (4)

when i raced i had everything except more timing adjustable fuel pressure regulator grinded egr walls in plenum and gutted maf sensor. I beat a 5.0 lx 5 speed by 3 cars i hear they run low 14's so i think i can run a 13.99

IROCThe5.7L

Heh, I raced my cousin from I believe 37 to 80ish, and I never shifted into third gear.

As far as timing, I went from the stock 6 to 10, and seen no difference (track times).

firebirdjones

Yep the 2.77's suck thats for sure. What really compounds the problem is the crappy gear spread in the 700r4. It's not a good drag racing transmission at all mainly due to the huge drop you have from first to second.
I recently built a 7.5 to put in the Iroc, and went with 3.42 gears. Hoping that will help the gear spread problem a little and the engine won't have to struggle to get rpms back up as much. Larry.