eb110americana

iTrader: (4)

I believe location also factors into it. And with good reason. There are over 7 million vehicles in LA, and pollution is a very real consideration here. As such, my 1998 has always required a dyno test with sniffers in the exhaust tips, tested under load at 2 speeds. This seems like the most fair test of emissions, as it is actually telling you what your car should be emitting in the real world (assuming you don't change the tune, parts, or fuel specifically for the test).

Long tube headers are an instant SMOG fail, as they move the cats farther away from the engine. This means they take longer to reach operating temp, which means worse emissions at start up for a longer duration.



Thanks Jim, that was super helpful! I'm definitely staying away from the LS7 clutch after reading that. Based on the recs of redbird555, it would seem that the Mcleod RST and Fidanza flywheel combo would be an excellent choice, but it ain't cheap. $752 just for the clutch, or almost triple the cost of the LS7 unit. I wonder if something made for less powerful applications would be more ideal in my case?

I honestly don't even know which clutch I would get, as the engine will be an LS3, but the transmission will be a T56, so do I spec the parts that fit with the stock trans, or that match the new engine? I suspect the flywheel would have to match the crank, but beyond that...?

I might just do this, as I have to get an alternator anyway (unless I pull it off my LS1--and it is an almost new AC Delco piece). I do have some nice Rockford Fosgate speakers in there, including a couple of 8" subs replacing the factory 6.5" Monsoon units. The head unit and amp are factory, but when those subs hit, they will dim the dash lights slightly. It might be a good precaution to go just a little bigger. Especially if the water pump will now be perpetually sucking electrons.

I'll probably just buy an oil pan with the baffles built in, as I will need a new one anyway. Again, do I go LS3 to match the engine, or LS1, to match the constrictive F-body subframe? Grinding stuff is not a problem for me. I have a heavy duty shaft-driven grinding tool (generally used by jewelers) I bought after burning out my 3rd Dremmel I'll simply need to know how close the tolerance should be on a scraper, in order to account for thermal expansion of the crank, block, and scraper itself. But that's probably one of the easier pieces of the puzzle to solve.

Another simple question: If I purchase a bare LS3 block, such as this, will I need to take it to a machine shop to get the cylinder bores and main bearings machined? I am fairly certain I will need to insert the freeze plugs, but I wonder how "finished" a GM parts block will be.

I have a dealer parts PDF for the F-body, which will come in handy. I was wondering if anyone had a good link to a complete parts list for the LS3, preferably with part numbers? The big pieces are easy, it's all the little nuts, bolts, sensors, clips, gaskets, O-rings, etc. that will certainly slow me down when I have to stop to order them.

JimMueller

iTrader: (9)

The LS1/LS2/LS3/LS7 short blocks are all pretty much the same on the outside of the actual cylinder case. I had a LS7 clutch with 13lb flywheel in the car mated to a LS1 when it received the LS3 transplant in summer 2010. There were no changes to the clutch parts, bellhousing or transmission needed. And I'm still using the same clutch assembly today. As I mentioned in that post, for me, I have convenience requirements which the non-OEM clutch assemblies don't meet.

Regarding the oil pan, get one for your frame style, unless you're going dry sump then it shouldn't matter... but then you have other challenges with parts placement.

Regarding that bare block, I would at least expect to take it to a machine shop to ensure everything is 'square'. You may find during assembly that certain clearances aren't to spec and you'll need to take it to the shop anyway. You'll need to have a machine shop balance the rotating assembly also.

I have a list of parts I ordered for my LS3 conversion, in an Excel spreadsheet. PM me your e-mail address and I'll send them to you. If you use the LS3 intake 'beauty cover', you will probably need to grind on the front of that cover to fit the throttle/cruise cabling bracket. We modified my existing bracket to get the car on the road that evening, but since then I've tried a couple different brackets, they all required grinding on that cover. I'll need to see what those part numbers were as they are not in the list.

eb110americana

iTrader: (4)

Thanks Jim, that helps a lot. It sounds like most everything outside the block can or should be LS1, including the clutch, oil pan, and even some of the sensors. Does this also apply to the flywheel? Are those even specific to fitting an LS3 vs. and LS1? How about the water pump? Would the LS1 part fit--or even be the correct unit, considering belt placement?

In terms of balancing the rotating assembly, would this not be resolved by having the crank balanced before ordering? Or is this a matter of them building the rotating assembly outside of the block, and then precisely removing material for minute variations? Since the block is brand new, direct from GM, would it really be out of spec? What is generally fixed in those cases?

PM sent for build list...

JimMueller

iTrader: (9)

Nothing behind the rear main cover needed to be changed... if it worked on my LS1 it worked on the LS3. You'll need to use the 24X crank reluctor wheel with your PCM, or else get the Lingenfelter 24X-58X converter box, search on that. You'll need LS1 MAP & knock sensors for PCM compatibility. The knock sensors install on the exterior sides of the block, you'll need to tap the existing holes. I already had a LS2 water pump on my prior LS1, and it works fine with the LS3. I re-used all my front LS1 accessories with the exception of upgrading to an ATI Superdamper, although the stock damper would have been fine.

If you order a complete rotating assembly, I would expect for it to already be balanced. I would still have it checked out by a local machine shop for peace of mind. Since the blocks are cast, the deck surface could be off by just a little bit from corner to corner (were talking a couple thousandths), which would mean the piston could be slightly closer to the head on one end causing uneven chamber sizes, piston-to-valve clearances, etc. So long as you have the minimum physical clearance you should be fine, but won't be optimal... it just depends upon how **** you want to be on the build.

My ISP's SMTP server is being cranky tonight, if it doesn't clear up soon I'll try another way to get you the list.

96capricemgr

iTrader: (1)

How did this thread get so long? LS3 will make within the proposed flywheel HP range with CAI, headers and a tune, give it enough gear to compensate for the LS3 lowend and enjoy.

You try and "build" such a mild engine and all you are doing is risking failure from **** local machinework or your own mistakes.
Start looking at all kinds of aftermarket stuff and inspection will get harder.
One of the above linked articles has the stock LS3 making 483hp with longtube headers, tune, electric waterpump and free flowing intake on an engine dyno. That means the talk of AFRs and aftermarket intake are absurd.
Granted longtubes are not going to work for CA inspection so shorties will be the ticket and still inside your goal range. You want to aim for the higher side of the range add a MILD cam and discuss with the vendor your expectations of valvespring life. That would likely put you over your goal for a lot less money than all the talk of chinese crankshaft, aftermarket topend etc.

eb110americana

iTrader: (4)

Thanks Jim, I got the build list. I do know about the 24x crank reluctor vs. the 58x that normally resides in the LS3. Since I am not married to any prebuilt engine, I will go the route of simply placing the correct reluctor for the LS1 computer to understand, rather than add expensive additional pieces. I have also finally finished reading the full 9 pages of the "UPDATED- L92/L76/LS3 Engine Into 99-02 F-Body" sticky, so I noticed that there is also a similar single pole (versus the four pole) timing chain gear required by the LS1 brain. Someone had mentioned on that thread that they did not think the '98 computer would work, so I posted looking for some clarity. So far, no replies there. Do you still have the factory '98 PCM in yours?

Your notes on the deck surface variations make sense. I will enquire when I find a local shop, if they can do this, or refer me to someone who can. At the same time, I will ask about the rotating assembly, especially if I don't order it all from one source.

96capricemgr:
I appreciate your notes on valve train life expectancy. That is definitely something I will bring up with the shop I select, as well as the cam vendor. With the rest of your focus on HP targets though, I think you are missing my goals here. This engine is less about the quantity of power it makes, and more about HOW it makes that power. There are myriad different ways to hit any number of power levels, but the character of the engine is more important to me. I would honestly rather have a 400 hp engine with a free spinning nature than a 500 hp one that never breaks a sweat. That mentality might not make any sense on a track, but on the street, it makes perfect sense to me. I have driven plenty of fast cars that I would never want to drive to work everyday, and while the LS3 is a fine engine, I feel it can be a lot more lively, even within my constraints of SMOG and fuel economy. That is worth the extra cost and effort to me.

JimMueller

iTrader: (9)

Yes I still use the OEM 98 PCM and original wiring harness. Some tuners may give you grief and blame their inability to properly tune the car on the lack of tables in the older PCM vs the last PCM released for the Fbodies, the '411' PCM. If you're starting from scratch it might make sense to start off with the 411 model and a matching harness. If you already have the older PCM, search around and collect all the changes and troubles people sometimes have while trying to convert to the newer PCM & harness so you're at least prepared for the challenges.

Yes you need the 1X timing chain sprocket/gear, PN 12576407, it is in the list. It uses a 3-bolt cam core, which is why the cam referenced in the list is listed as being a 3-bolt also.

96capricemgr

iTrader: (1)

You completely missed the point. You are barely looking to make anything more than stock power you aren't going to have to make any compromises or reinvent the wheel. Modest CAI, exhaust and tuning will get you there from a numbers standpoint on a bone stock engine and if you want to improve a stock engine a little milling or thinner head gasket will bump compression for better response.

Honestly if trying to build a lively daily driver engine from scratch the LS3 block would be a good start but I would NOT use the rectangle crap, I would nudge compression up a bit and pair with cathederals.

I say this as someone with an LS3 daily driver, let the A6 get into second gear before you put your foot in it and it is lazy. First is OK because it is 4.02:1. Stock gearing on the SS with LS3/A6 is about the same as a 4th gen f-body with A4 and 4.10s. The first gear of the A6 is used to mask poor lowend of the LS3.
If starting from scratch no way in hell I would look at that topend.

2015 SS barely gets better mileage than my truck both bone stock, the truck being Z71 and crewcab 10 years older and more than a thousand pounds heavier. If mileage and broad rpm range responsiveness are a concern again I would go cathederal. Even the EPA rating on the two vehicles is just 1mpg different.

My 500hp LT1 Caprice with 3800stall, 4.10s and cam ground on 108 LSA gets better mileage than either and is vastly more responsive but 12:1 compression, small head ports and stall will do that. It wont pass emissions anywhere though. The small head ports and compression are lessons you should take for your stated goals though.

The LS3 stuff is a cheap way to make a big HP number, the end, it is not the ticket for mileage, broad power range, or responsiveness.

JimMueller

iTrader: (9)

My car was not drivable for I'm guessing two months between when the LS1 came out and when I got it back with the LS3 installed. The first thing I noticed was a lack of throttle response... but it was a different cam, hadn't been tuned yet, maybe expectations and the elapsed time had a bearing on it also. I received a great price on both labor & parts and I didn't want to pay the FAST intake penalty (again) when the LS3 heads & intake worked well and were inexpensive. By the time I had it tuned in it had been so long I didn't know how the throttle response compared with the previous motor.

The fuel economy also dropped a couple of points... the best I get cruising in 6th gear below 2000RPM is around 25MPG. In town it's hard to say because I'm not trying to optimize for fuel economy and my fuel gauge is whack, so I have to fill up about every 100-110 miles, and the tank never takes more than about 10 gallons on a fill-up. Of course, the rolling resistance of my tires doesn't help, but that's my choice. I think I was getting 27-28MPG highway on the 347 LS1 with 5.3 heads, small cam, fast intake, 3.73 gears and narrower tires previously.