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LT1, LS1 etc...
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Posted by: VETTKLR

Alright Brand X-ers I want a little knowledge in your area.

What's the differences between the good-ole TPI 350 to the LT1, to the LS1?

What makes the Z-06 405 hp?

Now's your chance to shine, boys...dazzle me.

Posted by: LS1JAY

L-98 = 230 - 250 hp
LT1 = 275 - 300 hp
LS1 = 305 - 345 hp
LS6 = 385 - 405 hp

I had a L-98 Firebird and it was pretty quick running low-mid 13's with just a few bolt ons with the stock converter.

Maybe someone with some time on their hands can give you some detailed info!

Posted by: MikeT

I'm sure there are some articles floating around with the differences. But I'll try to explain the best I can.

I know alot more about the TPI (L98) motors than I do about the LT1 and LS1, So, I'll let the other guys fill you in on those.

For the TPI motors or L98 for the 350 (note, there was an 305 also.) You gotta go back to '85. It showed up on the vette in '85 and the f-bod got a 305 with the same injection setup. In '87 the 350 became available in the f-bod also. But w/ Iron heads, whereas the vette had aluminum heads.

The L98 uses a plain ol 350 block. There were 2 different head/intake manifold designs. 1st was the corvette shared by the f-body from 85-86. These were typical perimiter bolt valvecover heads with a standard SBC bolt angle for the intake. In 87 the f-body got center bolt valvecovers and a differnt angle for the intake to head bolts. A standard SBC intake can easily be modified to fit though. The corvettes kept the older style as they had aluminum heads.

TPI or tuned port injection is a long tube runner intake w/ a batchfire injector setup. Because of its design it produces alot of low-midrange torque but lacks in upper RPM power. Torque is avalable from idle and peaks around 3200. Hp peaks around 4400 and drops off by 5000. The weakest L98's were rated at 230hp - 330lbft. later f-bod models and vette L98's were rated as high as 255hp - 350lbft.

The major restriction on a stock L98 is the intake manifold. It simply chokes a 350 after 4500rpm. There are a ton of aftermarket parts available including an intake for vortec heads. The intake runners are probibly the next most restrictive, followed by the cylinder heads themselves. In all, its a very sexy looking fuel injection setup, but expensive to work with.

Nowdays there are better/cheaper injection systems to go with over the TPI setup. Some people have even had good sucess adapting a stock LT1 intake to the L98.

In all, it was a good motor at the time. Definatly superior to previous GM fuel injected motors. However, I feel it really was more suited to a truck than a sports or pony car.

check out this thread for some good TPI pics.

http://www.thirdgen.org/techbb2/sho...ht=polished+tpi

Posted by: LS1JAY

Don't forget the LT4 and the LT5 motors that came in some of the Vettes (ZR1 had the LT5)!
LT4 = 345 hp (a LT1 option with better heads and intake and also came in a few '97 SS Camaros)
LT5 = 385 - 405 hp (32 valves & 4 OHC's) they ran high 12's back in '90 with a good driver and had a LOT of potential!

Ls1's and LS6's are 346 cid and the L-98, LT1. LT4 & LT5's were all
350's

LS1's have a LOT more up top than the L-98's but the L-98's had some awesome low end torque!

Posted by: EvilLS1

About the only thing the LS1/LS6 has in common with the traditional SBC 350 is the center to center bore measurement of 4.4". Its a completely new design.

LS1/LS6 = 346ci, aluminum block with iron cylinder sleeves, Aluminum heads (15* valve angle), composite (plastic) intake, cast aluminum pistons, & cast nodular iron crankshaft. It also has equally spaced exhaust ports like a Ford.
The cam specs for the 98-00 Fbody are: 202/210 .496/.496 116 LSA. The 01-02 models have a different cam but I don't know the specs.

The factory hp (under)rating for the LS1 is 305-320. Most actually put down that much at the wheels though.

The LS1 & LS6 are very similar.. LS6 makes more power (better heads & cam).

Posted by: LS1JAY

Like Evil was saying... the LS6 get their power from a better cam and better heads. The '02 LS6 motors have a bigger cam than the '01's and the hp went from 385 to 405. I have a '02 LS6 cam in my car and it seems to pull a little harder on the top, but it's not a big diffrence that you can really feel. It idles about the same, maybe just a bit rougher but no one can tell that I have the cam in the car.

'02 LS6 cam specs... 204/218 .551/.547 117.5 LSA

CL: 120/115 Base Circle: 19.0mm (-0.0276')

Posted by: VETTKLR

Quote:


	TPI or tuned port injection is a long tube runner intake w/ a batchfire injector setup. Because of its design it produces alot of low-midrange torque but lacks in upper RPM power.

I saw this on an early 70's Chevy truck earlier this week. Batchfire injectors? More info, please.

Posted by: MikeT

injectors fire 1 "bank" at a time not sequencially.

IE the injectors on the passenger side all fire at once, then the driver side. As opposed to each injector's firing being timed for its cylinder.

Slightly less efficient but cheaper and easier.

Posted by: Proficio

By far the most vital difference between the LT1/LS1 and any other conventional engine(includes TBI or TPI) is the reverse flow coolant system. It allows for a much cleaner/cooler/hotter burning engine not possible with conventional cooling systems. Coolant enters the heads first so while still cool from the radiator it provides a cooler intake charge(low temp charge equals more air/better mixture) then after heated from the head goes into the block where high temps helps for a hotter more complete burn in the cylinder. Two electonically controlled thermostats control this.

We can talk about horsepower specs all day long but bottom line gm made some changes with the LT1 that didn't just include heads, cam, injection. How else would did we end up with a motor that can put out 300+ HP and still get 18 to 23 MPG.

Posted by: GMR

I may be wrong, but isnt the Gen III engine a conventional cooling system motor?

LS

Posted by: Black99SuperSport

yes only the LT-1/LT-4 were reverse flow.

everything to know about an LT-1

http://www.automotiverebuilder.com/ar/ar99928.htm

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