When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Any tips, suggestions, or tricks would be greatly appreciated. I bought a 91 L98 Z28 about a year ago. After replacing the intake gaskets and valve guide seals the car is a pretty strong runner. The transmission has been rebuilt at some point by the previous owner with a shift kit and I'm assuming Corvette shift servo. It shifts quick and firm. I think at some point the ring and pinion was changed out as well for a 3.73. I have not had the rear cover off yet to see for sure.
I remember reading years ago in a Super Chevy magazine i think about an adjustable fuel pressure regulator and how the TPI'S love more fuel. I have flipped around online a little and there isn't too much info out there and readily available for me. So I figured that I would ask you guys. I am not opposed to a head/cam swap either. Any info or suggestions would be helpful. I would like to stay with era correct mods if possible. I realize that the car will never be a rocket ship for all of those that are going to suggest the LS swap. lol
After a new tune up, plugs, dist cap, wires. Here is a list of some mods besides heads and cam of coarse. Throttle body coolant bypass (assuming you don't drive in cold weather), Move your MAT sensor to a cooler spot. Cooler thermostat, Custom tuned chip (delete EGR, AIR,VATS again, assuming you don't need emission inspection test), 1.6 roller rockers, adjustable FPR, Free flowing exhaust (headers), Free flowing intake mods. There are more that i can't think of, but these will keep the stock look you want.
After a new tune up, plugs, dist cap, wires. Here is a list of some mods besides heads and cam of coarse. Throttle body coolant bypass (assuming you don't drive in cold weather), Move your MAT sensor to a cooler spot. Cooler thermostat, Custom tuned chip (delete EGR, AIR,VATS again, assuming you don't need emission inspection test), 1.6 roller rockers, adjustable FPR, Free flowing exhaust (headers), Free flowing intake mods. There are more that i can't think of, but these will keep the stock look you want.
The tune up is done. Exhaust is done also except for headers. I do have a buddy that can burn the proms and datalog. Will the cooler thermostat trip the check engine light?
No check engine light. You may also want to get a cooler fan temp switch also. GM set these cars up to run hot. Now some will say by deleting the EGR (which needs to be programmed out of the ecm) that your motor will run hotter, that's why you run a cooler thermostat with a cooler fan temp sensor.
I just had a member here set me up with a new memcal (chip) since I was getting an EGR code. He deleted the EGR, AIR and VATS and then made some minor tweaks to the tune itself. Ive only put a couple miles on the car since installing the new memcal but so far so good. My main reason for going this route even though my engine is stock is because I wanted to delete the EGR and VATS. VATS is prone to failing and the cost of a new OEM EGR valve and new TPI gaskets was more than what I paid for a custom memcal. It was a no brainer for me,
you can look at my sig for my list of parts i put on. i went from a 305tpi to a 350 tpi. at this point if i step on the gas at about 3/4 i'm spinning tires. it's fun but i found out that the carrier in the LSD doesnt support 3.73's so i need to replace that, right now its just an open diff.
Look here! The best simple mods are a new complete full exhaust system with dual 2 1/2in cats, gut the air box and cut out 2 squares in the plastic under the air box where you can see the air tubing from the fog lights and K&N filters. Just doing those mods your car will run with a stock LS1 F-Body in the quarter mile. 13.3@104 with 3.23 gears. I did it before.
Look here! The best simple mods are a new complete full exhaust system with dual 2 1/2in cats, gut the air box and cut out 2 squares in the plastic under the air box where you can see the air tubing from the fog lights and K&N filters. Just doing those mods your car will run with a stock LS1 F-Body in the quarter mile. 13.3@104 with 3.23 gears. I did it before.
My drag racing knowledge is preschool level at best, and even I know this ain't possible.
I had a 1991 Camaro z28 5.7 L98 (G92 performance pkg). I purchased it used in 1993 with only 14k miles on it. I was the 2nd owner. Im from New England (Boston) and having only street raced my car around the city, i took it up to New England Dragway in Epping NH. It was a cool, fall Sat morning and i was able to get a best of 13.7 @ 99 mph and i only installed K & N air filters. It weighed 3380 lbs with me in it! Those 91-92 camaro z28's with the 5.7 G92 options were very fast out of the factory. Eventually after 5 yrs i got it to run a best of 13.0 @ 108 mph.
Last edited by MikeJR1991; 07-18-2018 at 09:06 PM.
I had a 1991 Camaro z28 5.7 L98 (G92 performance pkg). I purchased it used in 1993 with only 14k miles on it. I was the 2nd owner. Im from New England (Boston) and having only street raced my car around the city, i took it up to New England Dragway in Epping NH. It was a cool, fall Sat morning and i was able to get a best of 13.7 @ 99 mph and i only installed K & N air filters. It weighed 3380 lbs with me in it! Those 91-92 camaro z28's with the 5.7 G92 options were very fast out of the factory. Eventually after 5 yrs i got it to run a best of 13.0 @ 108 mph.
If they stop trying to re event the wheel, they can see their going faster with simple mods. Most of their cars have changed engines or the timing is off.
Look here! The best simple mods are a new complete full exhaust system with dual 2 1/2in cats, gut the air box and cut out 2 squares in the plastic under the air box where you can see the air tubing from the fog lights and K&N filters. Just doing those mods your car will run with a stock LS1 F-Body in the quarter mile. 13.3@104 with 3.23 gears. I did it before.
Why nope? What mods have you done? What year is your car and what state are you in?
To Which one? I have had my hands in a lot of different platforms. Before you get your panties in a wad you should know I believe the 5-speed G92 cars will be the high dollar one down the line because they are forgotten, unlike the 1LEs, and I do believe in another 20 years they will be the rare and fastest thirdgen.
But comparing them to a LS1 car??? LS1's are known to put 295-315 to the wheels in factory trim. The thirdgen and fourthgen cars are similar in weight, and L98 puts out at best 245 to the crank... that's only 208 to the wheels accounting for a 15% drive line loss. That is being generous.
So, CAI and a full exhaust is not adding 40%hp to the rear wheels. Just not doing it.
If you read my sig , right now I have a 88 IROC 350 with a Vortech, full exhaust, shift kit, injectors, gears and a few other odds and ends. Also have a Procharged/exhaust 96 LT4 Corvette and my DD is a 16' Challenger Scat Pack Shaker.... just recently sold my full bolt on Viper RT/10. I have also had an 86 T/A, 89 TTA, Dodge Stealth RT/TT, Fox Body 5.0, 2 S197, 95 LT1 6-Speed Z... even had a Ford Probe GT.... oh and a few trucks. None of them stock. I have been around the block.
Probably more relevant is I have 15 years experience as an automotive engineer for OEM's, Tier 1 and Tier 2 suppliers.
My locations is also listed on my Profile... Lansing, MI.
To Which one? I have had my hands in a lot of different platforms. Before you get your panties in a wad you should know I believe the 5-speed G92 cars will be the high dollar one down the line because they are forgotten, unlike the 1LEs, and I do believe in another 20 years they will be the rare and fastest thirdgen.
But comparing them to a LS1 car??? LS1's are known to put 295-315 to the wheels in factory trim. The thirdgen and fourthgen cars are similar in weight, and L98 puts out at best 245 to the crank... that's only 208 to the wheels accounting for a 15% drive line loss. That is being generous.
So, CAI and a full exhaust is not adding 40%hp to the rear wheels. Just not doing it.
Now since you don’t know me, I have 31 years experience with these 3gens. I have seen many different bolt on mods throughout the years until I seen them on the Dyno in the last 12 years. I know what works and not work.
The 90-92 L98 G92 N10 are the fastest. They range from 14.6@95-14.1@98 stock(depending on where you live in the country an if it’s a fast track). I have 1 3/4in SLP Headers, dual cats and 3in cat-back Hooker exhaust system. Gutted airbox and stock tuned. On the Dyno, the power was 257@4600/368wtq@3800. Now my car is a 1990 IROC L98 G92 N10 all stock everything else. These cars will get a good jump on an LS1 before the 1/8mi. After that, here they come because of The TPI Torque. Remember these cars are really choke up from the factory. You don’t hear guys using 1 3/4in SLP Headers with dual cats.
Now since you don’t know me, I have 31 years experience with these 3gens. I have seen many different bolt on mods throughout the years until I seen them on the Dyno in the last 12 years. I know what works and not work.
The 90-92 L98 G92 N10 are the fastest. They range from 14.6@95-14.1@98 stock(depending on where you live in the country an if it’s a fast track). I have 1 3/4in SLP Headers, dual cats and 3in cat-back Hooker exhaust system. Gutted airbox and stock tuned. On the Dyno, the power was 257@4600/368wtq@3800. Now my car is a 1990 IROC L98 G92 N10 all stock everything else. These cars will get a good jump on an LS1 before the 1/8mi. After that, here they come because of The TPI Torque. Remember these cars are really choke up from the factory. You don’t hear guys using 1 3/4in SLP Headers with dual cats.
A G92 Car is not, with headers and the bottom of the air filter housing cut open, running with an LS1 car. It's just not.
If you line up a stock 90-92 350tpi car, and a 98 LS1 car at a stoplight, the TPI car can put a few lengths on the LS1. Up until about 45-65mph, then the LS1 will go flying by. Exhaust isn't going to make up the nearly full second difference over a 1/4 mile. The LS1 will respond better to mods, and when was the last time anyone saw a stock LS1?
If you line up a stock 90-92 350tpi car, and a 98 LS1 car at a stoplight, the TPI car can put a few lengths on the LS1. Up until about 45-65mph, then the LS1 will go flying by. Exhaust isn't going to make up the nearly full second difference over a 1/4 mile. The LS1 will respond better to mods, and when was the last time anyone saw a stock LS1?
I don't agree with this either. The LS1 cars have, anywhere published, a better 0-60 time that the TPI cars.
A G92 car with Dual Cats, aluminum drive shaft, and performance gear already equipped goes 0-60 in around 6.1 sec with a quarter in 14.5.
A LS1 car with a Auto does it in 5.5..... now lets compare apples to apples here. If you hand pick the G92 car, I am hand picking an LS1 6-speed SS. That is 5.3 and a 13.8 1/4.
Headers, exhaust and cut open air box is not giving you .7 sec (roughly 70hp) in a 1/4 mile and the LS1 is winning to 60. The TPI may 60' better, but its going down hill quickly if the guy in the LS1 has any clue how to drive.
You can agree or disagree with anything you want. It doesn't change the fact that 90-92 350 TPI cars are well documented to run extremely low 14s. My Formula with over 100k miles on the clock ran 14.4s all day long with a best of 14.3. It wasn't in top tune, and the weather wasn't exceptional.
I'd be inclined to put my money on my sticky tires and 4L60 with gobs of torque next to some greaseball in a 98 WS6 with a 6spd. He's much more likely to light the tires while I pull away. It's worked out that way more than once.
A G92 car with Dual Cats, aluminum drive shaft, and performance gear already equipped goes 0-60 in around 6.1 sec with a quarter in 14.5.
.
That may be a bit conservative. I can remember stock, single cat, 2.77 gear, 5.7s getting into the 14s, even mid 14s.
Obviously, the N10, 3.27/3.23 cars were faster.
A friend ran his bone stock, (even paper filter), '92, B4C, 5.7 at the track, his first run ever on a track and did a 13.7. Could be a freak, but that's what his time was.
13.7 That's an awesome timeslip for a stock third gen! A factory freak. Ive never seen a "stock" TPI car get out of low 14s myself. But if you saw it Charlie I believe you. We do have hot, humid, sticky weather down south most of the time.
13.7 That's an awesome timeslip for a stock third gen! A factory freak. Ive never seen a "stock" TPI car get out of low 14s myself. But if you saw it Charlie I believe you. We do have hot, humid, sticky weather down south most of the time.
He took me for a ride in it once. Good Lord! It was the fastest stock 3rd gen I’ve ever been in! Last I heard, it was in Canada. I’m fairly certain those 92 B4C/1LEs had more agressive ECM and trans tuning.
I admit that this is the fastest time I had ever seen from the media, but they claim 13.9 seconds from an '89, G92, 5 speed. Fast forward to 2 minutes if you're in a hurry.
I'd be inclined to put my money on my sticky tires and 4L60 with gobs of torque next to some greaseball in a 98 WS6 with a 6spd. He's much more likely to light the tires while I pull away. It's worked out that way more than once.
I would take a bone stock TBI in an 1/8th against a driver that is going to light the tires up. I know I have turned in faster times than more powerful/capable cars when people have blown the tires off, missed a shift or fell asleep at the light. That is why you have to race instead of just doing a dyno and weigh in.
I think we have all seen some guys in fast cars do some really dumb things.
In the end a 92 (Or any year) TPI is limited by RPMs and number of gears.
I admit that this is the fastest time I had ever seen from the media, but they claim 13.9 seconds from an '89, G92, 5 speed. Fast forward to 2 minutes if you're in a hurry.]
I remember that show. Thanks for the memory. Comparing apples to oranges doesn't matter in this thread. When these cars were new, there wasn't any LS motors or aftermarket parts to improve anything. Anything that is done to them now was all learned over the years. The only comparison that you could do was against the Vette, which only had a few more HP than the Camaro. One thing for sure though, they looked better, preformed better, than any Mustang of the era.
My 87 305 5-speed was freakish fast. When it was stock the previous owner put a 160 thermostat, power pulley and disconnected the smog. I was neck and neck with 5.7 and Formula 350s. It was whoever got off the line quicker.
Once I got the heads done, exhaust restrictions removed, and all the other bolt ons, chip, tuning, centerforce clutch that grabbed like hell, etc.. it was car lengths faster than 350s.
People could not believe how fast the car was and always asked to see the engine. The engine looked stock except for ignition, wires, etc. I would beat my buddy’s 96 SS that had 305 hp and ran 13.4 1/4mile stock.
This is a photo that the original owner gave me that he used for the classified ad I bought the car from.. looked like a pretty stock 26k mile car back in 1994.. people were dumbfounded a 305 could be so fast.. I miss this car..
I beat a lot of cars by not spinning the tires.. I would figure out how to engage the clutch and get to WOT without any spin and I’d get a huge jump off the line. When I used my buddy’s slicks it was even better..
Headers and Open air box is not making up this distance.
Well the 2002 Camaro SS with the LS1 made 345hp and was much faster than the 1996 SS LT1 with 305hp..
My 87 would have smoked that IROC as well.. had a little more than headers and an air box though.. The LS1 would probably have beat my 87 if they got a good launch..
I’m fairly certain those 92 B4C/1LEs had more agressive ECM and trans tuning.
I believe it. Based on my experience with tuning on these 7730 ECM's, I'm fairly certain there's quite a bit of power being left on the table from the stock GM tune...
Leaning out the overly rich factory WOT AFR...
Utilizing the Corvette spark timing (if you can do it without pinging)
Crisp-ining up the accelerator enrichement fueling
Cold air duct and relocating the MAT and replacing it with a true IAT sensor AND re-tuning the air temperature vs fueling tables for that....
All of these things generated very noticeable improvements in throttle response and torque.
That's not to say going these things will turn a stock TPI into 400 hp engine, but I'm sure it'd generate markedly better ET's and 0-60 times...
Look here! The best simple mods are a new complete full exhaust system with dual 2 1/2in cats, gut the air box and cut out 2 squares in the plastic under the air box where you can see the air tubing from the fog lights and K&N filters. Just doing those mods your car will run with a stock LS1 F-Body in the quarter mile. 13.3@104 with 3.23 gears. I did it before.
Biggest line of BS I have ever heard, quite possibly.
So with exhaust, and about 15 minutes with a hacksaw, you are running 92 Firehawk times? Wonder why SLP didn't just do those couple easy mods to get the "Hawks" down to the easy low 13s?
Did you forget to mention the 100hp shot of nitrous in your mod list, possibly?
Biggest line of BS I have ever heard, quite possibly.
So with exhaust, and about 15 minutes with a hacksaw, you are running 92 Firehawk times? Wonder why SLP didn't just do those couple easy mods to get the "Hawks" down to the easy low 13s?
Did you forget to mention the 100hp shot of nitrous in your mod list, possibly?
Like I said before, none of the guy here or around these boards has never used SLP 1 3/4in Headers dual cats and 3in cat- back to prove my point in an automatic 3.23 G92 N10 L98 90-92. Dyno Dons Headers 1 3/4in would be even better. Remember the 90-92 L98 had more compression, little more cam and flat top pistons.
Like I said before, none of the guy here or around these boards has never used SLP 1 3/4in Headers dual cats and 3in cat- back to prove my point in an automatic 3.23 G92 N10 L98 90-92. Dyno Dons Headers 1 3/4in would be even better. Remember the 90-92 L98 had more compression, little more cam and flat top pistons.
Oooohhh, 1 3/4 SLP headers. I must have misread your original post!
100 RWHP, and 1.5 seconds off the 1/4 mile time is TOTALLY believable now!
October 27th, 2014,
I saw a 1990 Camaro G92 305 5spd 3.45 gear car go down the track at 13.9 @ 101 mph BONE STOCK.
I can certainly see a dual cat 350 going equally quick if not quicker with an Auto and 3.27 gears.
I have also seen a stock G-92 LB9/T5 dyno 220 RWHP and 280 RWTQ, with timing and fueling tweaks it hit 228 RWHP and 299 RWTQ.
Same day a stock 1997 LT1 Z28 Automatic ran a 13.5 @ 104.
A stock 1996 Corvette LT4 ran a 12.9 @ 108.
I ran a 13.9 @ 100 mph in a crew cab 2012 Nissan Titan with a CAI, Hypertech programmer, secondary catalyst delete and a magnaflow muffler. I cut a 1.98s 60' with an open differential in a truck on street rubber.
Air was near Zero DA, track was very well prep'd and we were all hauling @$$ and breaking personal bests. I think it was about 60*F outside, the sun was out and the racing was awesome.
I will also add I played with a TBI 305 car and got it into the mid 14s with the stock long block, 700r4, and a stock 3.27 locker 9-bolt that replaced the grenaded 10 bolt I bought the car with.
The car dropped nearly 1 full second from 1 3/4" shorty headers, high flow Y-pipe, 3.0" high flow cat and 3" magnaflow crossflow muffler, an open element, tweaked fuel pressure and timing along with subframe connectors and lca relocation. Dropped from a 15.5 @ 88 to a 14.5 @ 94 and still had the swirl ports and peanut cam in it.
October 27th, 2014,
I saw a 1990 Camaro G92 305 5spd 3.45 gear car go down the track at 13.9 @ 101 mph BONE STOCK.
I can certainly see a dual cat 350 going equally quick if not quicker with an Auto and 3.27 gears.
I have also seen a stock G-92 LB9/T5 dyno 220 RWHP and 280 RWTQ, with timing and fueling tweaks it hit 228 RWHP and 299 RWTQ.
Same day a stock 1997 LT1 Z28 Automatic ran a 13.5 @ 104.
A stock 1996 Corvette LT4 ran a 12.9 @ 108.
I ran a 13.9 @ 100 mph in a crew cab 2012 Nissan Titan with a CAI, Hypertech programmer, secondary catalyst delete and a magnaflow muffler. I cut a 1.98s 60' with an open differential in a truck on street rubber.
Air was near Zero DA, track was very well prep'd and we were all hauling @$$ and breaking personal bests. I think it was about 60*F outside, the sun was out and the racing was awesome.
I will also add I played with a TBI 305 car and got it into the mid 14s with the stock long block, 700r4, and a stock 3.27 locker 9-bolt that replaced the grenaded 10 bolt I bought the car with.
The car dropped nearly 1 full second from 1 3/4" shorty headers, high flow Y-pipe, 3.0" high flow cat and 3" magnaflow crossflow muffler, an open element, tweaked fuel pressure and timing along with subframe connectors and lca relocation. Dropped from a 15.5 @ 88 to a 14.5 @ 94 and still had the swirl ports and peanut cam in it.
Ok, well if that is all true, an LS1 F-body, would have been running 12.50s at about 112-114 that day
The point? Its all relative. A 15 second car in Colorado may be a 13 second car at sea level. However, an L98 with exhaust and a hole cut in the inlet ducting isn't touching an LS F-body, anywhere, period.
I owned a G92 1991 Z28, Formula 350s, 305 Iroc, currently own a 1992 L98 TA, 1991 305 TPI Formula, etc etc. I also owned a 2000 SS M6, 98 TA A4, 95 Z28 M6, and 99 Z28 M6.
Having owned all of the above, I can state with 100% confidence an L98 with exhaust and a cutout is not hanging with an LS A4 with 2.73s and a bad driver.
It's not even close, or a "drivers race" or anything of the sort. The L98 has a torque advantage from idle to about 2k rpms. Everywhere else in the powerband, the LS car has a GIGANTIC advantage, HP and TQ.
Just gets really old listening to "fish stories" about 1/4 mile times on message boards.
Ok, well if that is all true, an LS1 F-body, would have been running 12.50s at about 112-114 that day
The point? Its all relative. A 15 second car in Colorado may be a 13 second car at sea level. However, an L98 with exhaust and a hole cut in the inlet ducting isn't touching an LS F-body, anywhere, period.
I owned a G92 1991 Z28, Formula 350s, 305 Iroc, currently own a 1992 L98 TA, 1991 305 TPI Formula, etc etc. I also owned a 2000 SS M6, 98 TA A4, 95 Z28 M6, and 99 Z28 M6.
Having owned all of the above, I can state with 100% confidence an L98 with exhaust and a cutout is not hanging with an LS A4 with 2.73s and a bad driver.
It's not even close, or a "drivers race" or anything of the sort. The L98 has a torque advantage from idle to about 2k rpms. Everywhere else in the powerband, the LS car has a GIGANTIC advantage, HP and TQ.
Just gets really old listening to "fish stories" about 1/4 mile times on message boards.
while I agree with you I must say that having driven several brand new LS1 Camaro there’s the possibility of GIGANTIC acceleration gaps between them.
I do believe it’s 100% possible and PROBABLE that the fastest l98 modded as said could beat the slowest ls1 powered fbody in a 1/4 mile racing directly against each other with equal drivers. Not all LS1s could perform like the majority of them did.
Ok, well if that is all true, an LS1 F-body, would have been running 12.50s at about 112-114 that day
The point? Its all relative. A 15 second car in Colorado may be a 13 second car at sea level. However, an L98 with exhaust and a hole cut in the inlet ducting isn't touching an LS F-body, anywhere, period.
I owned a G92 1991 Z28, Formula 350s, 305 Iroc, currently own a 1992 L98 TA, 1991 305 TPI Formula, etc etc. I also owned a 2000 SS M6, 98 TA A4, 95 Z28 M6, and 99 Z28 M6.
Having owned all of the above, I can state with 100% confidence an L98 with exhaust and a cutout is not hanging with an LS A4 with 2.73s and a bad driver.
It's not even close, or a "drivers race" or anything of the sort. The L98 has a torque advantage from idle to about 2k rpms. Everywhere else in the powerband, the LS car has a GIGANTIC advantage, HP and TQ.
Just gets really old listening to "fish stories" about 1/4 mile times on message boards.
Funny you say that I have a slip that I ran against a 1998 C5 Auto the same day. 13.2 @ 107 is all he had!
Funny you say that I have a slip that I ran against a 1998 C5 Auto the same day. 13.2 @ 107 is all he had!
Now, LS vettes are only trapping .7 and 6mph ahead of 305 TPI f-bodies and full size Titan pickups.......
See how this starts to fall off a cliff quickly, and violently? Before the end of the thread, ZL1's and CTS-V's will be a "drivers race" against LG4 berlinettas.....
04-11-2016, 07:58 PM
, right now I have a 88 IROC 350 with a Vortech, full exhaust, shift kit, injectors, gears and a few other odds and ends. Also have a Procharged/exhaust 96 LT4 Corvette and my DD is a 16' Challenger Scat Pack Shaker.... just recently sold my full bolt on Viper RT/10. I have also had an 86 T/A, 89 TTA, Dodge Stealth RT/TT, Fox Body 5.0, 2 S197, 95 LT1 6-Speed Z... even had a Ford Probe GT.... oh and a few trucks. None of them stock. I have been around the block. 
It doesn't change the fact that 90-92 350 TPI cars are well documented to run extremely low 14s. My Formula with over 100k miles on the clock ran 14.4s all day long with a best of 14.3. It wasn't in top tune, and the weather wasn't exceptional.
