: Finding the lsot 25 HP



Jackrabbit Speed
10-26-04, 10:06 PM
I declined my purchas of a 1988 STS because there was antifreez in the oil.

I have found a nice 1988 SLS. (69,000mi) I hear that it has 25HP less. Why? and where can I find it. I'm pretty sure I'm going to buy this car but want to inhance the HP to STS standards or better. Any help would be appreciated.

Best Regards

illumina
10-26-04, 11:10 PM
i'm not a N* expert on this forum, but i'll give this one a go.

i think there are camshaft differences between the 2 engines, that may be the reason for the power differences. also with the cam differences, there are computer changes too. from what i can make of it, you are pretty much stuck with the 275 hp you are getting with the sls.

BTW, some people here seem to have had decent luck by changing the exhaust on their cars, maybe it will be more benificial for an sls than the sts... :hmm:

Spyder
10-26-04, 11:34 PM
I also think that you mean a 98 sts and sls? Anyways, the sls has more lower end torque than the sts, so people say its quicker off the line, but the sts will take it on the highway. I've not yet driven an sls, just my 94 STS, but many swear by the higher torque and the slightly lower hp. There's also more aggressive gearing in the STS than in the SLS. Illumina is right about the cams, too...SLS is a great car as well, and theories put forth have said that they've probably not been driven as hard, due to the targeted audience and such...which means they're less prone to breakage. I dunno how well that holds up, but its something that has been tossed around on this forum before. Good luck with whatever you decide!!!

Jackrabbit Speed
10-26-04, 11:47 PM
Thanks for the info. I'm just currious I use to have a 96 Impalla SS. Will the Cad be as quick? I'll be pleased if it is!

Spyder
10-27-04, 12:14 AM
I've not driven an SS, but I would think that the cad should be quicker...I've beaten many a 90's Mustang GT, and every damned honda or yota on the road without nitrous. :burn:

Jackrabbit Speed
10-27-04, 02:17 AM
KOOL ! :coolgleam

danbuc
10-27-04, 02:42 AM
Since I have my factory Service manual for my 1998 STS handy, I can give you the exact specifications of both engines.

To start this off, the STS has the L37 engine(300 hp/295 lb ft of torque), and the SLS has the LD8 engine(275 hp/300 lb ft of torque).

L37:

Vin ID- 9

Valve Lifters-
Force required to compress(Valve closed): 53 lb @1.19 in
Force required to compress(Valve open): 109 lb @0.823 in

Camshaft-
Valve Timing(With ramp at 0.100 mm lift), Intake opens: 13 degrees BTDC
Intake closes: 73 degrees ABDC
Exhaust opens: 51 degrees BBDC
Exhaust closes: 13 degrees ATDC
Valve lift, Intake: 0.370 in
Valve lift, Exhaust: 0.339 in
Duration(@0.100 mm lift), Intake: 266 degrees
Duration, Exhaust: 244 degrees
Valve overlap(@0.100 mm lift): 26 degrees

LD8:

Vin ID- Y

Valve Lifters-
Force required to compress(Valve closed): 46 lb
Force required to compress(Valve open): 92 lb

Camshaft-
Valve Timing(With ramp at 0.100 mm lift), Intake opens: 9 degrees BTDC
Intake closes: 55 degrees ABDC
Exhaust opens: 51 degrees BBDC
Exhaust closes: 13 degrees ATDC
Valve lift, Intake: 0.339 in
Valve lift, Exhaust: 0.339 in
Duration(@0.100 mm lift), Intake: 244 degrees
Duration, Exhaust: 244 degrees
Valve overlap(@0.100 mm lift): 22 degrees

(BTDC): Before Top Dead Center
(ABDC): After Bottom Dead Center
(BBDC): Before Bottom Dead Center
(ATDC): After Top Dead Center

Other than the differences mentioned above, the two engines are completely identical.

Theoretically, you could just swap the heads, and adjust the timing and it would work. You might have to change computers for it to communicate with the engine properly too. I think it would have been worth looking for an STS anyway.

Good Luck with the car ;)

Jackrabbit Speed
10-27-04, 02:49 AM
Great Info, Thanks! :thumbsup: Dan, what do you know about drive ratio difference between the two ?

danbuc
10-27-04, 03:26 AM
To be honest with you, I'm not sure. The service manual does not point out any specific difference between the 4T80E tranny connected to the L37 engine or the 4T80E tranny connected to the LD8 engine.(final drive ratio for diff...ect....ect). Sorry :(

danbuc
10-27-04, 03:28 AM
I think that was being discussed in the thread below this one.(Transmission Question), or something like that. You might be able to find the answer there.

Ranger
10-27-04, 11:36 AM
Great Info, Thanks! :thumbsup: Dan, what do you know about drive ratio difference between the two ?
I think the SLS final drive is 3.11 and the STS is 3.71