LT1 "L99" Motor - The 1947 - Present Chevrolet & GMC Truck Message Board Network

tmcdanielhsd · 12-22-2003, 02:21 AM

Has anyone had any experience with one of these motors ? Apparently, they are identicle to 5.7l lt1's except they are 4.3l.
At any rate, I have a chance to buy one with all accessories including wiring harness and computer for$700. It only has 35000 miles on it and came out of a wrecked state bureaue of investigation car.

miket · 12-22-2003, 02:38 AM

I wouldn't touch it. It's not worth the effort and money. Buy a true LT1....

dinnut · 12-22-2003, 03:15 AM

why is it not worth it? an lt1 will run 2-3x more than that. the 4.3l's arent too bad from waht ive heard.

neonlarry · 12-22-2003, 03:23 AM

the only person that I know that has driven a car said it felt like 2 little elves trying to push the car, and having a rather hard time of it. I would pass on that engine and keep looking for an lt1.

dinnut · 12-22-2003, 03:29 AM

oh. is that why. ok im stupid im thinking of another engine... maybe its the new 4.8 i thought you were talking abotu

miket · 12-22-2003, 03:40 AM

"baby" LT1's are dogs....plus you get the pain in the A@# optispark to go with it.

tommie · 12-22-2003, 11:27 AM

your lucky they aren't tring to passs it off as an lt1.

most people do.

swdobbs · 12-22-2003, 11:51 AM

Its clear a few of the previous posts are speculating and have never driven a L99.

I own a '94 B-body, loaded leather, posi... w/ the L99. I've done some "bolt-ons", a reprogram from BH for $100 and the #4400 beast pulls hard to 138 mph gets 26 mpg without my foot in it.

The only diff is the displacement and the injector size. I will grant that the baby LT1 is down on torque.

Check out the impalassforum.com posts for the L99, I know of a .30 over with LT4 heads and it runs 12's off the bottle.

swdobbs

Mark540 · 12-22-2003, 12:42 PM

How can you tell by looking at teh motor it is not a 350?

miket · 12-22-2003, 12:49 PM

It's next to impossible to tell. They look identical.

An interesting note. All the hoopla about the 94-96 SS and Caprice regarding performance....including the police edition 9C1 was and has been based on the LT1 motor. These cars weigh in excess of 4200lb's....they are heavy.

The true LT1 motor behind these cars was not a monster HP motor...just 260hp. Whats decieving is the 330lb/ft of torque. Torque usually comes from cubic inches, unless there have been performance mods done to a smaller motor to achieve greater output.

One for one, stock for stock, I will take the LT1 5.7 over the L99 anyday.

swdobbs · 12-22-2003, 03:07 PM

I agree apples to apples, the stock LT1's I've driven have it hands down over a stock L99.

However if you truly can end up with all the LT1 parts sans block and heads for the fore mentioned price ($700), it is worth considering. The LT1 small parts will kill a budget build, just ask me about the last set of vette sensors.

I am running an L99 while rebuilding a LT1 block using LT4 heads, the final install will require nothing more than a bump in injecter size to 21/24lbs...same manifold/sensors/exhaust/ECM etc... as simple as it gets.

A good LT1 i.e. Rancho Recyclers in CA goes for $2750.

An extra $2000 buys the "Painless Harness" to run both the L99 and LT1, a good LT1 block, new heads and you have the ability to work out the bugs by running the L99 while you hand built a new .30 over LT1.

swdobbs...

70short · 12-22-2003, 06:39 PM

There is the L98 (350) TPI which was A pre LT1 vette motor 85-91(Camaro, Firebird). Also pre Optispark. I think A TPI setup in our trucks would be

and fuel efficient!!!

12-22-2003, 02:21 AM	#1
tmcdanielhsd Registered User Join Date: Nov 2003 Location: hillsborough, nc Posts: 10	LT1 "L99" Motor Has anyone had any experience with one of these motors ? Apparently, they are identicle to 5.7l lt1's except they are 4.3l. At any rate, I have a chance to buy one with all accessories including wiring harness and computer for$700. It only has 35000 miles on it and came out of a wrecked state bureaue of investigation car. __________________ 69 C10 2wd, LT1, 4L60E, 4.11 2000 F350, 4wd CC 7.3 PSD, DRW 1995 F350, 2wd, 7.3 PSD, DRW

12-22-2003, 02:38 AM	#2
miket Registered User Join Date: Jan 2003 Location: Seattle WA Posts: 1,466	I wouldn't touch it. It's not worth the effort and money. Buy a true LT1.... __________________ FocuzTech Performance Evergreen Protective Coatings Gatorhyde...the best kept secret in spray in bed lining & protection

12-22-2003, 03:15 AM	#3
dinnut Registered User Join Date: Apr 2003 Location: missouri city, tx Posts: 4,486	why is it not worth it? an lt1 will run 2-3x more than that. the 4.3l's arent too bad from waht ive heard. __________________ 70 longbed 496/th400/Ford 9"

12-22-2003, 03:29 AM	#5
dinnut Registered User Join Date: Apr 2003 Location: missouri city, tx Posts: 4,486	oh. is that why. ok im stupid im thinking of another engine... maybe its the new 4.8 i thought you were talking abotu __________________ 70 longbed 496/th400/Ford 9"

12-22-2003, 03:40 AM	#6
miket Registered User Join Date: Jan 2003 Location: Seattle WA Posts: 1,466	"baby" LT1's are dogs....plus you get the pain in the A@# optispark to go with it. __________________ FocuzTech Performance Evergreen Protective Coatings Gatorhyde...the best kept secret in spray in bed lining & protection

12-22-2003, 03:23 AM	#4
neonlarry Registered User Join Date: Feb 2002 Location: Vacaville, CA Posts: 2,746	the only person that I know that has driven a car said it felt like 2 little elves trying to push the car, and having a rather hard time of it. I would pass on that engine and keep looking for an lt1. __________________ 70 C/10 Light Red 350/TH350, HEI, Duals w/40 series Flows, 91 seat, LED taillights 99 Pontiac S/C GTP, SLP Ram Air hood, GMPP Konis & springs 95 Neon ACR, MP PCM, AFX UDP, 3.0 CAI

12-22-2003, 11:27 AM	#7
tommie 97' Tahoe 2dr/2wd Join Date: Jul 2002 Location: Huffman,TX Posts: 1,168	your lucky they aren't tring to passs it off as an lt1. most people do.

12-22-2003, 11:51 AM	#8
swdobbs Registered User Join Date: Oct 2002 Location: MT Posts: 98	L99 owner Its clear a few of the previous posts are speculating and have never driven a L99. I own a '94 B-body, loaded leather, posi... w/ the L99. I've done some "bolt-ons", a reprogram from BH for $100 and the #4400 beast pulls hard to 138 mph gets 26 mpg without my foot in it. The only diff is the displacement and the injector size. I will grant that the baby LT1 is down on torque. Check out the impalassforum.com posts for the L99, I know of a .30 over with LT4 heads and it runs 12's off the bottle. swdobbs

12-22-2003, 12:42 PM	#9
Mark540 Registered User Join Date: Feb 2003 Location: Fairborn,OH Posts: 203	How can you tell by looking at teh motor it is not a 350? __________________ 1970 GMC Burb 4x4 - 68 Chevy Front, FI LT1, 4L60E 1970 Chevy Impala 47,000 miles 2001 BMW 540i 6-speed 2002 Dodge Ram 1500 4x4 w/20's

12-22-2003, 12:49 PM	#10
miket Registered User Join Date: Jan 2003 Location: Seattle WA Posts: 1,466	It's next to impossible to tell. They look identical. An interesting note. All the hoopla about the 94-96 SS and Caprice regarding performance....including the police edition 9C1 was and has been based on the LT1 motor. These cars weigh in excess of 4200lb's....they are heavy. The true LT1 motor behind these cars was not a monster HP motor...just 260hp. Whats decieving is the 330lb/ft of torque. Torque usually comes from cubic inches, unless there have been performance mods done to a smaller motor to achieve greater output. One for one, stock for stock, I will take the LT1 5.7 over the L99 anyday. __________________ FocuzTech Performance Evergreen Protective Coatings Gatorhyde...the best kept secret in spray in bed lining & protection

12-22-2003, 03:07 PM	#11
swdobbs Registered User Join Date: Oct 2002 Location: MT Posts: 98	LT1 v.s L99 I agree apples to apples, the stock LT1's I've driven have it hands down over a stock L99. However if you truly can end up with all the LT1 parts sans block and heads for the fore mentioned price ($700), it is worth considering. The LT1 small parts will kill a budget build, just ask me about the last set of vette sensors. I am running an L99 while rebuilding a LT1 block using LT4 heads, the final install will require nothing more than a bump in injecter size to 21/24lbs...same manifold/sensors/exhaust/ECM etc... as simple as it gets. A good LT1 i.e. Rancho Recyclers in CA goes for $2750. An extra $2000 buys the "Painless Harness" to run both the L99 and LT1, a good LT1 block, new heads and you have the ability to work out the bugs by running the L99 while you hand built a new .30 over LT1. swdobbs...

12-22-2003, 06:39 PM	#12
70short Registered User Join Date: Sep 2003 Location: Boise ID Posts: 609	There is the L98 (350) TPI which was A pre LT1 vette motor 85-91(Camaro, Firebird). Also pre Optispark. I think A TPI setup in our trucks would be and fuel efficient!!! __________________ "72" Red CORVETTE 4-speed 350 "70" Chevy Short Bed early stages of resto. Edel 600 cfm carb Weiand Stealth Intake HEI shorty Headers 4/2 Drop 295 50R 15 TOYO on 10 inch wide corvette rally rims at all 4 corners. "CHEVY RULES"

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