its time to stir the pot,just cuz it hasnt been stirred in a while. I was just wondering how much faster my near stock auto 94 feels out on the highway,(only mods are cats delete,tuneup,and cut lid right now,)compared to my 90 conv,which basically had every bolt on without removing the valve covers.Granted,my 90 was a high 12 second car,but it still doesnt feel like it has this pull out on the highway,but probably made as much rearwheel horsepower.we know LT1's(mid 13's) are about .5 quicker stock than L98's,(low 14's)and have about 45 more rearwheel horsepower,but how much if/does the gap close when both are modified?I've seen mid-low 12's for LT1's when modded,compared to high-mid 12's for L98's.I mean any bolt on that doesnt touch oil,while keeping the longtube runner setup.list of mods,dyno #'s and 1/4 mile times appreciated

 

Not much pot stirring here. Your SOP dyno seems almost backward unless you are pulling 5G + on the Hwy. The TPI car should feel much stronger then the LT1 but be a bit slower then the LT1 at the strip. The two motors make power different the TPI and Super Ram intakes make a lot of TQ down low and typically run out of gas up high where a LT1 makes a power pretty well across the board (A little less down low a little more up top) Both motors have advantages and disadvantages. The L98 is a great motor to mod because it is a standard SBC configuration so things such as after market head selection is almost unlimited and you can use darn near any SBC block you want including after market ones such as Dart. Now the LT1 is great because it responds to Mods well and can produce power very quickly. I feel it is the LT1 head design that allows the LT1 to respond so well to Mods and still run like stock. The other good thing about the LT1 is you can run higher CR without knock because of the reverse cooling.

Here are my thoughts
L98 makes better low end power much more selection of performance parts and can be made to be stupid fast if it is SB GM you can probably make it work with this combo and even the intakes.

LT1 Better power up high and responds to mods well but limited in parts selection, heads you have 4 choices GM AFR TF and edlebrock Blocks one GM

 

Thats what I mean,my 94 still feels a little faster up top,but I know my 90 was faster in the 1/4,as my 94 is probably capable of a mid-low 13,compared to my 90,which was in the 12's.my 85 and 87 also had alot of boltons,and I know they had alot more pull down low,but out on the highway,or from a roll,my 94 would eat them.

 

Yes but what where your 60's with the 90?? I suspect they where prety darn good showing more low end TQ. On the Hwy you are starting to get into the power band for the LT1 and it will start to show a little even with a more stout L98. The LT1 feels its best from above 3K to redline, they just love to pull so on the Hwy I could see where you think the LT1 would do well but start from a dead stop and see what happens. On a 1/4 mile run Tq is king because you have to get 3000 Lbs moving and thats where TQ is at. Now with that said the LT1 does make great TQ just not as well as the L98 and a modified one running in 12's realy should feel a lot stronger then a stock LT1 out of the hole.

 

Take a look at Vic'89's L98 which runs mid 12s and MrMojo's LT1 which runs similar numbers. Both have stock cam & heads.

 

1.78 with a 2600 TC,3.54's,and dragradials,in a conv.no less.I used to race a friends 99 6spd Z28.I would pull out alot,have a few cars on him,then by third he would catch me.we would be door to door,by the end of the 1/4.Out on the highway,he would wax me though
I would have had to get into the motor to take him.

 

ok,thats a good comparo,I looked at VIC'89's sig has he ever had his car dynoe'd?with those traps,its got to be around 280.Thats what also I was curious about,is that around what the limit of power is for a N/A L98 with LTR's,and a little over 300 for LT1's?

 

If you are willing to stroke it(383) or larger the sky is the limit.

I like my L98

 

When you're talking modifications there is no way to compare apples to apples on these two engines.

Your L98 with bolt ons might make a ton of torque and run 12's and still not feel as fast on the highway as the LT1 simply because of the LT1's ability to turn higher revs. It's the classic HP vs Torque battle, which ultimately always amused me because they are the same thing. HP depends soley on torque and RPM, so the real argument is LOW RPM torque vs HIGH RPM torque. Your L98 has more low end, your LT1 has more upper end. As such in the higher revs the LT1 is gonna feel quicker, which the TPI is going to feel faster stoplight to stoplight. Your observations are perfectly normal.

A good example is my friend's car. He has a '87 Iroc with a 350 SBC, carb, Hot Cam, v-6 trans and 3.73 gears. He swears up and down that his car feels faster than mine, despite the fact that I can run 12.7's and he runs 14.3's. His gearing makes his car feel really fast, but he runs out of RPM really quickly and it fades. So yeah he's right. He puts more torque to the ground than I do from a dead stop until the top of first gear. The problem is once he has to shift, I'm still in 1st gear where I am then effecitvely putting more power to the ground. Likewise I'm halfway through second while he's shifting into third. Plain and simple I walk away from him like he's sitting still although this car "feels" faster.

Its all about how you drive the car and what you perceive as fast. As far as the two engines go, one is really no better than the other as far as HP capacity belongs. Both can make insane power if you've got enough money to spend. The SBC has the advantage of having a larger variety of aftermarket parts, but so long as you've got money either one can make killer power.

 

with everything you said nathan.It all goes back to intake tract length of the 2 engines.TPI's are about 21 inches which creates a resonance effect when the air enters the cylinder,which creates more pressure,compared to the LT1's 3 inches which doesnt take advantage of any resonance.I do miss my L98's off the line power,I could basically "tap"the gas on some of the ones Iv'e had and could light the tires(especially my GTA).They ate tires up faster though!I would like to have that "feel"back,without losing this topend.and I'm guessing with 3.73's,and the right converter I will,but most of the driving I do right now,is highway,so I'm not sure about the gears.That should be a main point when others are looking for a C4,the type of driving you will be doing.If you mainly do street driving,stick with the L98,you wont miss(or need to pay for)the LT1's extra power.If you travel alot on the highway,and like that passing power,go for the LT1.Another comparo I remember was with my 90 GTA,had all the SLP boltons(intake,exhaust,converter,gears)M y friend had traded had just got a 02 ZO6,when I took it for a test drive,I wasnt impressed with the power on the street compared to my GTA,which probably had 100hp less.I was like,"this is the mighty 405hp ZO6" however,from a roll,or out on the highway,that thing pulled like a freight train, and although we never raced,I'm sure I wouldnt be able to count on 1 hand how many car lenghts I would have been behind.

 

vette&f-bod lover, I believe Vic's '89 is turning out around 330chp which would be close to 280 at the wheels.

BTW, he runs skinnies up front, slicks out back and pulls 1.7x short times. I'm not sure but think that MrMojo is running skinnies on his A4 Vette too.

I think both the LT1 and the L98 can be modded for close to 400chp, though the L98 requires LT runners & base to breath better up top.

If you do the SR or MR intake then it's really no longer a L98 is it. Then the runner length is closer to that of a LS1 than a LT1.

 

One thing I notice when modifying L98's, it doesn't take to many mods to match the Et's of Lt1 but it takes quicker ET to match the MPH and what would be the highway acceleration of a Lt1.

 

LT1's can make 400hp with basically a cam,ported heads and headers.L98's(stock 350)need alot more than that with long runners,and wont be very streetable,whereas the LT1 will.not to say,that the L98 wont be faster with less horsepower.

 

I wouldn't say that a 400 HP L98 would be un-streetable, it would just drive quite differently than it did stock. It can be every bit as streetable as the comprable LT1.

 

My 90 350 c.i. L-98 made almost 400 hp at 4800 rpm and 500 ft lb of torque at 4000 rpm on the dyno yet was easily drivable on the street. The bottom end was stock. AFR 190 cc heads, LPE 74211 cam. 1.6 rockers, Super Ram intake, 52mm TB, 1-5/8 long tube TPIS headers with no cat and flowmasters, Mcleod alum flywheel and dual disk clutch, thru the bumper air inlet, open air filter, etc. Never ran at the drags but on the street with Kumho 315 Victoracers and a G-tech I consistantly ran low 14 e.t.'s and 108 -110 mph. As mine was a road race car, the suspension was set up for the track not the drags. I consistantly smoked the tires until I got into 3rd gear. Based on the mph, I'd guess it was a 12 second car. I know from my track experience that I could smoke LT-1's. I could get off the corners so much faster. My current stock LT-1 is strong but its definitely not as fast as my old L-98. FWIW.

Larry

 

Thats not a longtube setup though, like I said,its really hard for a N/A 350 L98 to be streetable and make over 400hp.not saying it cant be done,but I dont know of to many out there,that have good idle/driveability.HP=torque x rpm/5252.The long runners wont allow the airflow to make the RPM to produce the power.its easier if you change to a SR,or MR,or go with bigger cubes,like 383 or 406.

 

I think looking at a HP number realy looses the whole point of the diffrences in the motors. You must look at the TQ of the L98 and the Hp for the LT1 to get the real picture. Just drag race the two cars stock side by side and it becomes clear the diffrences. My guess the L98 gets the LT1 out of the hole and the LT1 runs it down and wins. Now mod the L98 and it is the same thing your biggest gains are in TQ not HP, look at vetracer for example 500 FtLbs of TQ and 400 HP, almost 100 more #s of TQ then HP. Now look at my combo 400+RWHP and 400 RWTQ the numbers are almost the same. While the LT1 produces more HP it produces it later and with less TQ. Again I think GM has improved every Corvette motor since 84 untill today but thats just me. The LS1 was a huge leap IMHO over both of these motors but I love both the L98 and the LT1/4

 

yes,but HP is what you feel out on the highway(highrpm)a car with more peak hp with equal gearing/weight etc.will accelerate faster than onewith less hp,and more torque,which is exactly what I'm feeling

 

Remember HP is strictly a function of torque. Trying to compare the two is simply confusing. If an engine A makes more torque than engine B at a given RPM it makes more HP as well. Thus it isn't a matter of if HP or torque is better. Eliminate torque completely and look at horsepower, it paints a MUCH easier picture to look at. The L98 in stock form produces more horsepower, sooner, than the LT1. The LT1 has a higher peak number but it takes longer for that power to come on. Which car is ultimately faster? IF EVERYTHING ELSE IS HELD EQUAL, the car with the greatest area under the HP curve will be faster, provided that the race is long enough to fully exploit the power curve.

L98<LT1<LS1<LS6<LS2<LS7 in stock form. Start modifying them though, and well I still have to bet money on the LS7, but really it all depends on how much money you want to spend.

 

Vette and F-bod lover,
I dont know what problem your friend's Z06 had, but I seriously doubt that your SLP modified F-body was faster than a typical Z06 on the street. I have both an 02 Z06 and an 95 LT1 C4 and have driven many L98 F-bodies and Vettes over the years and neither the LT1 nor the L98 cars compare in thrust at any speed to the Z06. The first 25 feet or so in first gear may feel slightly more responsive in an L98 and perhaps an LT1, mainly because the Z06 is spinning (more likely hopping) its rear tires, but after that, its good bye. My car is stock (plus no DRs) and runs severely traction limited 12.3's at 117 at greasy Englishtown Raceway Park. My Z06 can do traction limited 0-60s (measured with a G-Tech) between 4.18-4.34 sec in 90 degree weather on the street. On the same street, in the same heat, the best my LT1 could do is a 5.27 and most runs are between 5.35 and 5.50.

Going back to the original inquiry of this thread, IMO, the L98 would be my choice to modify. Although the LT1/LT4 can be easily modified to make very substantial power, the options for doing so are fairly limited. If you check this site, you will see that most people modify their LT1s in more or less the same manner, ported or non-ported LT1/LT4 heads, hot cam or the like, etc. In every case, you are limited in creativity to the OEM intake system of the LT1/LT4 and the LT1/LT4 heads (Yeah I know Edlebrock is now making heads for these engines). You can get much more creative modifiying the L98 engine since the L98 specific TPI system and heads can be replaced with any number of various aftermarket carb, intake manifold, head, and cam combinations for Gen I SBCs. It is mainly the L98-specific TPI system that make these engines feel wheezy on the highway. I've driven a number of modified 350 ci SBCs that were fairly civilized, could wind to 7200-7500 rpm and made great power doing so. Although these engines were a little light on torque below 3000 rpm, they had gearing that allowed the cars to get quickly into the power band. The pull through the gears is extremely satisfying and the sound of a SBC with a carb at 7000+ rpm is unlike anything I have ever experienced in a fuel injected L98 or LT1 variant. Of course, if your not willing to scrap the L98 TPI system, then I would go with the LT1/LT4. At least an LT1/LT4 wont embarass itself from a roll-on on the highway before or after being modified, as is apparently the case (according to this thread) with modified L98s.