: STS Computer Into Deville?



CaddyDaddy97
01-25-04, 05:31 PM
Hi, I was wondering what the difference was between the STS's 300hp engine and the Devilles 275hp engine. Is it just the computer? Could I put the STS computer into my 97 Deville and get 300hp? Thanks.

caddydaddy
01-25-04, 11:17 PM
The cams are different on the lower powered Northstar. I'm sure the computer is programmed differently to compensate for the different cams as well. But if you changed the cams, and the computer, or had the stock one reprogrammed, I don't see why it wouldn't work???

Aurora By Olds
01-28-04, 12:13 AM
I changed cams in my 4.0 when I did the headgaskets.
The only difference is fuel delivery with the computer. The MAF and O2's will compensate fule delivery for the little bit more airflow, so you shouldn't have anything to worry about there.
I noticed a little bit more HP on the top, but I also punched out the CAT in the process, and I think I'm lacking in the torque band now though.
But its easy to do though, especially if you already have the engine torn apart...

BeelzeBob
01-28-04, 03:09 PM
I changed cams in my 4.0 when I did the headgaskets.
The only difference is fuel delivery with the computer. The MAF and O2's will compensate fule delivery for the little bit more airflow, so you shouldn't have anything to worry about there.
I noticed a little bit more HP on the top, but I also punched out the CAT in the process, and I think I'm lacking in the torque band now though.
But its easy to do though, especially if you already have the engine torn apart...

CaddyDaddy97
The cams, not the computer, is the difference in the power. The computer cal "agrees" with the cams but is not the driving force. Incidentally, on the 93-99 engines it is only the intake cams that are different between the L37 and the LD8 engine.

Aurora by Olds
The 300 HP cams caused your loss in low end torque. It is real and it is the cams...not the cat being gutted. That is why those cams were never put in the Aurora 4.0....it just doesn't have the displacement to pull off the more aggressive L37 cams without a significant loss in low end torque.

Aurora By Olds
01-28-04, 09:14 PM
I figured I'd be lacking in the torque band, but not this much. The difference is pretty significant.
I was hoping I could use some simple mods to build the torque back up. Obivoulsy, I need to do something with the exhaust, because it is still the stock system. I want to run true duals, but that would be a feat in itsef. I dont know if there is any size that would help my torque out much at all, and I also dont know if I can get enough flow through true dual 2" to make it worth the while either.
I would also appreciate it if anyone could help me with some TQ mods that might help.
Otherwise, I have no other choice but to keep building up on the HP band.

BeelzeBob
01-28-04, 09:54 PM
I figured I'd be lacking in the torque band, but not this much. The difference is pretty significant.
I was hoping I could use some simple mods to build the torque back up. Obivoulsy, I need to do something with the exhaust, because it is still the stock system. I want to run true duals, but that would be a feat in itsef. I dont know if there is any size that would help my torque out much at all, and I also dont know if I can get enough flow through true dual 2" to make it worth the while either.
I would also appreciate it if anyone could help me with some TQ mods that might help.
Otherwise, I have no other choice but to keep building up on the HP band.
Honestly , I would recommend going back to the LD8 cams that you had originally. That is the simplest and easiest way to get the torque back. There is quite a loss in low end with the L37 cams in the 4.0. About the only way to "create" torque is with more compression or with added displacement....soo....deck the heads 1mm...or...pop in a 4.6....LOL Trust me, the 4.0 just does not work with the L37 cams in the production Aurora with an automatic trans. The added power you are getting is all above 5600 RPM...below that you are netting a loss. And the power peak with those cams in a 4.0 is about 7000 RPM....way past where you can use it in the Aurora with a 4T80E. The other thing is the gearing...I don't know which gear you have in your car but even with the 4.6 Northstar the gearing was dropped to 3.71 to work with the L37 cams...and that was with a 4.6. Hard to accept that those cams are just too aggressive for that engine/trans/gearing/combo but they are. Go back to the LD8 cams and you 'll be a lot happier.

The Aurora engines that Shelby put in the Series 1 cars were production 4.0 liter engines that Shelby swapped the L37 cams intake cams into. In that car with a manual trans and 4.11 gears they worked fine...oh...and that car weighed only about 2600 pounds. You could drive around the lack of torque with the gearing and the manual trans and use the top end power. Even in that package the L37 cams were "specials" with a different cam timing. The cams were "degree'd" slighlty differently to get a little low end back, even with the manual trans et. al. there was just too much loss. And that car had a very very low backpressure exhaust with true duals and headers and an open inlet system . It had everything going for it that an Aurora doesn't and it still didn't have enough low end with the production L37 cams.

We did a fair amount of tuning trying to make the L37 cams work in the Aurora to offer a high output version and they were just too much to offer decent driveability and all around performance. The engine would make more HP with the L37 cams but the car was much slower with them. The area under the torque curve is what accelerates the car...and the L37 cams in the 4.0 is really deficient in this respect.

One other note....the Olds AeroTech car that set the world land speed records for endurance at 10K and 25K kilometers had a production Aurora 4.0 in it for the endurance record runs. That engine was a stock 4.0 with the L37 cams, dry sump, open headers, open inlet with ram air and it made 300 HP at 6200 RPM...and was still climbing for the moon at 7200 RPM. The car was geared, though, to run constantly at 6000 RPM so the cams made good power for that application as acceleration was not an issue...plus it had a 6 speed manual gearbox.

Note also ,regarding the cams, that the GXP Bonneville just out for 04 has the Northstar engine with the LD8 engine (and LD8 cams...) but with the 3.71 final drive normally used with the L37 cams. It is quicker 0-60 than the L37 engine in the STS.... that area under the torque curve with the LD8 cams is tough to beat. Those are the cams the Northstar was optimized for originally and the L37 cams came along as the "need" for a bigger power number and differentiation for the performance package evolved. The L37 cams do make more power...but...you have to have the gearing and the rest of the package to utilize it.

Aurora By Olds
02-02-04, 12:53 PM
Thanks, bbob. I've kept the original cams, just in case I was unhappy with the performace I ended up with.
I do have the higher (3.42?) gears, which definitly makes a difference in the torque range. I wish I had the autobahn/STS tranny, but that's another story.
I was contemplating changing the cams back, and figured it would take me roughly a day to take it apart and change the cams, and then finish it up the next.
I was wondering if there is any way to change the cams without removing the front over and disturbing the timing at all. What I was thinking was just removing the timing gear from the intake only and pulling it back from the cam, supporting it with dowel pins, or small sleever bars or something. I would zip tie the chains to each of the sprockets to be sure they didnt move or jump a tooth, and then quickly just swap the cams. I've only had this motor apart once, and granted it was only 2 months ago, but I dont remember much about the cam gears and tensioners. Theoretically, it should work, but im guessing there is probably something in the way that I am missing.
Let me know what you think. It might just be easier than it looks, as are many things on these caddies.

BeelzeBob
02-02-04, 03:46 PM
Thanks, bbob. I've kept the original cams, just in case I was unhappy with the performace I ended up with.
I do have the higher (3.42?) gears, which definitly makes a difference in the torque range. I wish I had the autobahn/STS tranny, but that's another story.
I was contemplating changing the cams back, and figured it would take me roughly a day to take it apart and change the cams, and then finish it up the next.
I was wondering if there is any way to change the cams without removing the front over and disturbing the timing at all. What I was thinking was just removing the timing gear from the intake only and pulling it back from the cam, supporting it with dowel pins, or small sleever bars or something. I would zip tie the chains to each of the sprockets to be sure they didnt move or jump a tooth, and then quickly just swap the cams. I've only had this motor apart once, and granted it was only 2 months ago, but I dont remember much about the cam gears and tensioners. Theoretically, it should work, but im guessing there is probably something in the way that I am missing.
Let me know what you think. It might just be easier than it looks, as are many things on these caddies.

Yes, you can change the cams without taking the front cover apart but, no , you cannot do it as you imply.

There are automatic hydraulic tensioners on the cam chains that are also spring loaded with built in , automatic mechanical racheting mechanisms that trap and hold the tensioner when the engine is off to prevent any slack in the chains. If you took the sprockets off the cams and allow even the least little bit of slack in the chain the tensioners would take up the slack and zzziiipppp the rachet would lock and you would not have enough play in the chain to get the sprocket back on.

There is a service tool that looks like a funny set of vise-grip pliers that will reach into the cam chain cavity at the front of the head and hold the chain in place to prevent any slack from creeping in during the swap. The other approach is a tool that I have seen around and have seen several people make is a detail that bolts to the cylinder head at the front with a large dowel pin that butts up against the end of the cam. Loosen the sprocket bolt and remove it, install the detail with the dowel and slide the cam sprocket onto the dowel of the special tool by prying with a screwdriver. Take out the cam and the sprocket is suspended in it's original position on the special detail. Install the other cam and slide the sprocket back onto the cam....

You MUST use one of these tools to hole the cam chains or sprocket in order to change the cams in the engine.....or pull the front cover off to reset the cam chain tensioners.

Aurora By Olds
02-02-04, 10:51 PM
Ahh, yes, I forgot about the auto tensioners.
Im sure I could fabricate a detail with some dowel pins that would work well for that.
It would sure be much easier than trying to get the front cover off, while still in the car. By the way, you wouldnt happen to know where to get the vise-grip pliers at, would you? Ive seen them in the shop manual, but I dont believe there was a part number or name for them....
Thanks again, you've been a huge help.

BeelzeBob
02-02-04, 11:49 PM
Ahh, yes, I forgot about the auto tensioners.
Im sure I could fabricate a detail with some dowel pins that would work well for that.
It would sure be much easier than trying to get the front cover off, while still in the car. By the way, you wouldnt happen to know where to get the vise-grip pliers at, would you? Ive seen them in the shop manual, but I dont believe there was a part number or name for them....
Thanks again, you've been a huge help.

KentMoore tools. J38815 - cam chain tension holder

If you can make up the detail with the dowel to slide the sprockets onto I would do that. The tool to hold the cam chain works OK...but...it is not nearly as secure as the tool to slide the sprocket onto.....