Difference between an LT1 & L98?
01-24-2013, 03:16 AM
#41
Race Director
The real question you are after is can a L98 be modified to make 300 HP and that answer is yes. The L98 engine design is a typical SBC and it would be very easy to acheive 300 HP.
To tell you the truth both engine designs can be modified to make impressive power but if your your goal is to make race level power (600 HP plus) the L98 (SBC) design get the nod since it has much more aftermarket support and many more parts available to achieve those goals.
To tell you the truth both engine designs can be modified to make impressive power but if your your goal is to make race level power (600 HP plus) the L98 (SBC) design get the nod since it has much more aftermarket support and many more parts available to achieve those goals.
)For perspective, that same cam/exhaust/head/TPI swap didn't "just" get me to LT1 power level. In SAE (factory) terms, I'm hitting that same 300hp level by 3k rpms. So, I'm getting to LT1 "fun" a whole lot faster. Close-ratio 6-spd doesn't hurt that fun level.
Really, it says alot about the ability to mod a TPI too. Maybe it even speaks to the Challenge Cars thread recently posted in the C4General forum? Hmmmm.....
Doesn't mean I'm not thinking about trying another intake for perspective...but there's a lot of fun to be had -- even if/when shifting at 4.5k rpms. Just look at those vids from "weekend" auto-x racers and you'll see that's where they shift.
Application can be a factor....as you pointed out with the comment about "IF" you're building a 600hp race motor.
Of course, for the reason the OP posted....pulling up this ANCIENT, rediculous thread, there's no value in this post as it's all headed to the boneyard!
and
IBTL!
01-24-2013, 10:42 AM
#42
Race Director
BTW...the relevant thing (to me) is put a fine-tooth-comb to what you're asking. Say why you want to know what's different. Mention exactly how you drive a car. KNOW exactly how you drive a car. Build for that purpose.
Too many pick too big/small of a particular item. Too many don't consider how parts combine to work as a whole. With regard to the L98vsLT1, both sought after that....though time, technology, and progress found the newer car to be the better one.
Of course, that will always be true.
Too many pick too big/small of a particular item. Too many don't consider how parts combine to work as a whole. With regard to the L98vsLT1, both sought after that....though time, technology, and progress found the newer car to be the better one.
Of course, that will always be true.
01-24-2013, 11:22 AM
#43
Le Mans Master
I agree with the others that you can't just swap LT1 stuff onto the L98.
However, I did run across something interesting. You can swap the truck Vortec heads onto the L98. The vortec heads are very similar ports to the LT1, so you can get similar flow with them. The vortec intake mounts differently, so neither the LT1 or L98 intakes fit, but Scoggin Dickey parts has a lower intake base for the vortec heads with the L98 parts. They advertise that it brings it up to the LT1 level with these heads and lower intake on a stock L98.
To me this seems like it might satisfy a lot of concerns by getting the better heads while still retaining the distributor. (although I have had good results with 5 or 6 cars with high mileage and never had an optispark failure.) Other mods can still be made to cams, etc. if you are wanting more.
Intake:
https://sdparts.com/details/scoggin-...-center/sd3816
Heads:
https://sdparts.com/index.php?q=deta...enter/sd8060a2
or
https://sdparts.com/details/scoggin-...nter/sd8060ra2
However, I did run across something interesting. You can swap the truck Vortec heads onto the L98. The vortec heads are very similar ports to the LT1, so you can get similar flow with them. The vortec intake mounts differently, so neither the LT1 or L98 intakes fit, but Scoggin Dickey parts has a lower intake base for the vortec heads with the L98 parts. They advertise that it brings it up to the LT1 level with these heads and lower intake on a stock L98.
To me this seems like it might satisfy a lot of concerns by getting the better heads while still retaining the distributor. (although I have had good results with 5 or 6 cars with high mileage and never had an optispark failure.) Other mods can still be made to cams, etc. if you are wanting more.
Intake:
https://sdparts.com/details/scoggin-...-center/sd3816
Heads:
https://sdparts.com/index.php?q=deta...enter/sd8060a2
or
https://sdparts.com/details/scoggin-...nter/sd8060ra2
01-24-2013, 11:26 AM
#44
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St. Jude Donor '05
Agree the Vortecs shold run about the same they go about 220/150 out of the box..intakes a little stronger than the LTx. Exhaust is well...
If you go searching for power meaning modding the heads/porting the LTx can take it...Vortecs not so much..
Dont buy used Vortecs either chances are they got a crack somewhere in them. Putting bigger valves in is risky too they are meant to be a torque head and nothing more. The LTx can be made to go either way.
If you go searching for power meaning modding the heads/porting the LTx can take it...Vortecs not so much..
Dont buy used Vortecs either chances are they got a crack somewhere in them. Putting bigger valves in is risky too they are meant to be a torque head and nothing more. The LTx can be made to go either way.
01-24-2013, 12:50 PM
#45
Le Mans Master
My last combo on my 91 before I went LSX was fastburn vortec heads, mid range cam, LT1 stock manifolds and exaust toped off with a HSR vortec intake. It was all cheap and should have net me around 400CHP. I never got a chance to drive it much.
If I was looking for cheap and easy HP I would bolt on some L31 heads a vortec intake with LT runners and a midrange cam. The LT1 or aftermarket exhaust becomes a must at this point.
01-24-2013, 02:05 PM
#46
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92-97 so actually 6 model years.
Here is the scope on GM engine development. The L98 was around doing its thing and being awesome. The they wanted to take on the big dogs and got the LT5 in 90. Over at GM Powertrain they where PO'ed that they did not get a chance to make this Euro-killing engine. So they in the late 80's early 90's redid the Small Block Chevy Gen1. The LT1 is a Gen 2, it was an engine for a new era of fuel economy and ever increasing emissions. They thought the most they could get was 250HP out of a SBC. Well, they hit 300, then with more development they realized 350 and even 400HP was within reach. They started work on a Gen 3 engine but realized soon they needed a clean sheet design. This still born Gen 3 became the LT4 in 96. The LS is a totally clean sheet design that started development in 93.
The SBC Gen 1 is the grandfather and in its L98 form, the still cool and relevant grandfather. The LT1 is the not far from the tree son, the Dad (LT1) realized if his kind was to survive he needed to mate with something totally new and better. Hence, the grandson (LS) is in spirit (basic layout, 4.40 bore spacing, legendary status) the same as his father and grandfather, he is ready for the new 21'st century and its unique automotive threats to the 2 valve pushrod existence.
The LS is a great engine like all SBC's. Everyone raves about it, for the same reasons that made the 55 SBC the HOT ONE. Easy to mod and make HP, reliable and durable, cheap to make, modify, and build, etc....
Nothing is created in a vacuum, the SBC is a great design and a mature one in the L98, it made the LT1/LT4 great, the great LT1/LT4, made the LSX series great, it is a evolutionary thing. They build on one another and make their breed better.
Here is the scope on GM engine development. The L98 was around doing its thing and being awesome. The they wanted to take on the big dogs and got the LT5 in 90. Over at GM Powertrain they where PO'ed that they did not get a chance to make this Euro-killing engine. So they in the late 80's early 90's redid the Small Block Chevy Gen1. The LT1 is a Gen 2, it was an engine for a new era of fuel economy and ever increasing emissions. They thought the most they could get was 250HP out of a SBC. Well, they hit 300, then with more development they realized 350 and even 400HP was within reach. They started work on a Gen 3 engine but realized soon they needed a clean sheet design. This still born Gen 3 became the LT4 in 96. The LS is a totally clean sheet design that started development in 93.
The SBC Gen 1 is the grandfather and in its L98 form, the still cool and relevant grandfather. The LT1 is the not far from the tree son, the Dad (LT1) realized if his kind was to survive he needed to mate with something totally new and better. Hence, the grandson (LS) is in spirit (basic layout, 4.40 bore spacing, legendary status) the same as his father and grandfather, he is ready for the new 21'st century and its unique automotive threats to the 2 valve pushrod existence.
The LS is a great engine like all SBC's. Everyone raves about it, for the same reasons that made the 55 SBC the HOT ONE. Easy to mod and make HP, reliable and durable, cheap to make, modify, and build, etc....
Nothing is created in a vacuum, the SBC is a great design and a mature one in the L98, it made the LT1/LT4 great, the great LT1/LT4, made the LSX series great, it is a evolutionary thing. They build on one another and make their breed better.
01-24-2013, 05:13 PM
#47
2nd Gear
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Lt1 with l98 top end
Here's my situation I spun a bearing on my 88 l98 and I have a good lt1 setting around can I use my l98 top end on my lt1 block? I don't care if I lose the horsepower. I just want to keep my factory harness.. And this all happened the day I got fired so I have very little funds just looking for a quick cheap fix until I do a lsx swap thanks
01-24-2013, 06:16 PM
#48
Team Owner
Pro Mechanic
Reading comprehension: 101
You already asked that same question here:
And I answered if for you, here:
Since you added a bit (Want to keep your stock harness), you can run an LT1 in your car w/the stock harness, with an "LT1 manifold conversion" which is simply modding the LT1 intake to accept your stock distributor. Although the tune won't be ideal, it will probably be "good enough" and work just fine.
You already asked that same question here:
And I answered if for you, here:
Since you added a bit (Want to keep your stock harness), you can run an LT1 in your car w/the stock harness, with an "LT1 manifold conversion" which is simply modding the LT1 intake to accept your stock distributor. Although the tune won't be ideal, it will probably be "good enough" and work just fine.
Last edited by Tom400CFI; 01-24-2013 at 06:27 PM.
01-26-2013, 08:09 PM
#49
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L98 in 1991 was either 245hp/345lbft or 250hp/350lbft depending on which rear ratio u had. L98 had better exhaust design except for having 3 cats. Better savaging effect with the y-pipe up front vs true dual. If you are concerned about performance just concentrate on your torque and run your car in the peak range.
So not wanting to hi-jack the thread, what is the difference (quickly, if possible) between the Y-pipe vs true dual? I am guessing you are talking about running two separate pipes down the length of the car. But don't you still have to fit a balancer tube between the two? (think it goes towards the front). Thats what I had in my 68 Holden Premier with Chevy 350, many years ago.
You can start a new thread if this helps?
We do not need to have a cat fitted here, so I could even get rid of it completely.
Might as well do it right while it's being done.
Cheers Kev.
01-26-2013, 08:17 PM
#50
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St. Jude Donor '05
You dont need a crossover 2 pipes works just fine.
Some like to do it for their own reasons.
Makes working under there easier without it esp dropping the trans.
Dread the next time I have to drop mine.
Some like to do it for their own reasons.
Makes working under there easier without it esp dropping the trans.
Dread the next time I have to drop mine.
01-26-2013, 08:33 PM
#51
Race Director
H-Pipes are rarely desired/used -- but are still considered balance pipes for equalizing engine bank pressures. Also, for exhaust resonance in rear Y-pipes.
Y-Pipes are the stock L98 config. The front pipes merge into a single, larger pipe. They can (and do) also split back into dual outlets. With optimum-size piping, this y-pipe config has been considered somewhat similar to X-pipe functionality. Though, like an H-pipe, considered to be less than "ideal".
Scavenging discussion with anything less than full-headers and the elimination of cats is also marginally worthwhile. There really isn't THAT much cam overlap to worry about it -- until you get well into the 220 duration cams. That isn't to say every little bit helps. And, unless I misunderstand, the comment about L98's having better exhaust is flat wrong.
Another thought on the difference between L98's and LT-1's. The former has a flat-butt...the later, round. That means the LT-1's have a better booty. Especially if you're into thinking of your car as "your girl"!
Last edited by GREGGPENN; 01-26-2013 at 08:36 PM.
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01-27-2013, 01:02 AM
#53
Max G’s
OK, My car is due for an exhaust repair job v-soon, and after reading this thread maybe I should look at a different system to install, and maybe get a bit more power?
So not wanting to hi-jack the thread, what is the difference (quickly, if possible) between the Y-pipe vs true dual? I am guessing you are talking about running two separate pipes down the length of the car. But don't you still have to fit a balancer tube between the two? (think it goes towards the front). Thats what I had in my 68 Holden Premier with Chevy 350, many years ago.
You can start a new thread if this helps?
We do not need to have a cat fitted here, so I could even get rid of it completely.
Might as well do it right while it's being done.
So not wanting to hi-jack the thread, what is the difference (quickly, if possible) between the Y-pipe vs true dual? I am guessing you are talking about running two separate pipes down the length of the car. But don't you still have to fit a balancer tube between the two? (think it goes towards the front). Thats what I had in my 68 Holden Premier with Chevy 350, many years ago.
You can start a new thread if this helps?
We do not need to have a cat fitted here, so I could even get rid of it completely.
Might as well do it right while it's being done.
You will hear various opinions on true duals and y to one. Bottom line is scavenging effect whether a y pipe in the front or an x pipe as close to the front as possible. With that ask yourself, am I weight conscious? If so, then the y into one is most likely your choice. One pipe is lighter than two, even if it is a .5" to 1" larger in diameter. My choice and opinion is for the y to one then y to dual out back.
01-27-2013, 02:22 AM
#54
Safety Car
You will hear various opinions on true duals and y to one. Bottom line is scavenging effect whether a y pipe in the front or an x pipe as close to the front as possible. With that ask yourself, am I weight conscious? If so, then the y into one is most likely your choice. One pipe is lighter than two, even if it is a .5" to 1" larger in diameter. My choice and opinion is for the y to one then y to dual out back.
Years back I did a before and after test on a consistent bracket car. The Before was a 383-SR motor that I shifted at 6000 rpm with 1 3/4" headers into the stock front Y, through a gutted cat, out the stock rear Y and through Muffler eliminators...... switched to true 3" dual exhaust behind the headers.
My ET improvement reward for this money spent was.... nothing.
There might have been 5 HP gain, but it was lost by the extra weight of the dual exhaust. I wish I had weighed the two exhaust systems at the time, but I would guess it was around 50 lb heavier.
I guess what I am saying.... is that for most people, I suspect the stock pipe diameter is hunky dory. But, I know GM went with I think 2.75" pipe with the LT-1 motors.... so I dunno, maybe there is, just wasn't on my 400+HP 383.
Food for thought.
04-25-2017, 07:53 PM
#55
7th Gear
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04-26-2017, 03:33 AM
#56
Burning Brakes
08-25-2022, 09:08 PM
#57
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L98-
230 HP
330 Torque ft. lbs
5.7 L
LT1-
300 HP
330 Torque ft. lbs
5.7 L
It seems like the L98 and LT1 are mostly alike except for the difference in HP and compression ratio and the LT1 has a optispark while L98 doesn't..
In other words, what makes the LT1 get 300 that the L98 doesn't have? How can a L98 be modded to "become" a LT1?
230 HP
330 Torque ft. lbs
5.7 L
LT1-
300 HP
330 Torque ft. lbs
5.7 L
It seems like the L98 and LT1 are mostly alike except for the difference in HP and compression ratio and the LT1 has a optispark while L98 doesn't..
In other words, what makes the LT1 get 300 that the L98 doesn't have? How can a L98 be modded to "become" a LT1?
