Most use an electric water pump, and the 2 row timing chain with any kind of radical cam that turns any RPM. I have had no problems making large 106 lobe center cams idle fine with an LT1 box. Had a 106 lobe center cam in mine for almost six years. Anybody that drives a decent running LT1 car, then gets into a decent running LS1 car, then tells you the LS1 is smoother due to a faster processor or multiple coils also believes in ghosts, aliens and unicorns.

GM has gone to that system for long term emissions compliance. They have to certify those cars will pass emissions at 100,000 miles with the hood having never been opened.

How do you run a decent timing chain with the crank position sensor in place?
Surely people aren't using a single row chain with those conversions?

 

No issues here.

The single row LT4 extreme duty timing set works great with a GM timing cover, crank sensor, and reluctor wheel. Other installations are using some of the best double row timing sets on the market by using the billet aluminum TPIS timing cover, which allows plenty clearance for a crank sensor and reluctor wheel.

 

I didn't know about the timing cover. That is the only way a serious engine should be done. Knowelgable, serious engine builders won't even consider that LT4 chain.

 

So what is the chain of choice with an Mezerie water pump? Cloyes double roller?

 

just to back ed up a bit... I just got my cam with ~50 degrees of overlap @.050 and ~105 lsa to idle at 1050 reliably, cold start it gets a little grumpy below 1400 (E85). This is on the stock pcm with 60# injectors! I can imagine with ed's magic touch it would idle even better than it does now

My take on this whole swap... really you're not going to get more than ~7000 rpm out of a HR cam setup without spending a lot of investment both money and time (testing) wise, so what's the point of ditching the stock pcm? For the serious guys, the LS1 conversion won't cut it. For the basic guys it's a waste of time and money. I spent my money on DFI, because I'll NEVER outgrow the system. No 8000 rpm limiter, I can run 3 dry stages on it, closed loop with a wideband, 3 bar MAP, real time tuning, etc. If you can't find someone locally that will tune DFI, FAST, etc, then you probably don't want to spend your money locally to get an LS1 setup tuned.

 

Thought I mentioned Rollmaster. You can buy them at Scoggin Dickey GM, a sponsor here. Billet gears, bottom gear keyed so you can move the cam on 2 degree increments with no buttons, etc. Woodro Josey put me onto them. He has probably built more record setting LT1 engines than anybody. Good pieces. I use over .800" lift, and over 900 lbs open spring pressure at 8500 with no problems at all.

 

cloyes 3145

 

~50* @ 0.050"? I always thought seat-to-seat gave the most accurate calculations Regardless, 50* isn't that radical anyway, so it's no surprise it idles well.


Well, I'm sure glad we got your take on it - I was starting to lose sleep I agree that to each their own and that there are a few ways to go fast, but I find it hilarious that your logic to completely discount the EFI system is predicated on the features of another aftermarket system that 99.9% of the LT1 market would never capitalize on. I doubt even you will.

Ed has certainly got a point when he says that a well running LT1 PCM car has little to gain to switching to the EFI set-up, other than a lighter wallet. However, the LS1 PCM is a better unit, and there are far more tuners available for it, and no more reliance on (or having to care for) the opti-spark. To me that wasn't a problem, but finding a tuner was.

 

Hey, at least I spit out an actual VALUE of overlap and the results I've experienced instead of a generic "less than 107 lsa won't idle" that gets regurgitated on here. I wasn't so sure about the streetabilty of that much overlap, especially in a HR where the seat-to-seat duration is very large , but I've been pleasantly surprised so far.

Everyone is discounting the LT1 PCM system, based on the features of an LS1 PCM swap that 90% of the LT1 market will never capitalize on It's the same principle, but if I'm spending money on an upgrade, I want the best one for my money. That's what you're not reading... there is very little cost difference between these swaps, it could go either way for which is cheaper depending on options.

Like I said, if you can't find a "tuner" who will touch an aftermarket EFI system, I wouldn't want to spend my money for those "tuners" to do an LS1 setup. The software for aftermarket setups is free and comes on a CD or is available for download online.

My point, is that there are 3 groups of people looking at this swap. 1. The people who want to go faster. 2. The people who think the LS1 PCM will outperform the opti and LT1 PCM 3. The people who want to be cool saying they have an LS1 computer.

Guess which group of people needs the system, then guess which groups of people outnumber the others... You probably wouldn't have swapped a cam 10+ degrees bigger if you weren't in group #1

 

That is a limited perspective.

How about...
- 4L80E support
- electronic throttle (drive by wire) support
- nitrous support (with custom OS) to add/remove fuel/spark from the PCM
- forced induction support (with custom OS)

There are many ways of looking at this.

Then there are the engine swappers who purchase a used SBC/LT1 and have to make decisions about buying a new engine harness, tuning, and freshening up the parts on the engine (for example the optispark and ignition) before installing the engine/transmission. The costs of then choosing to use the LS1 PCM can easily become justified for more reasons than getting the car down the dragstrip as fast as possible.

I disagree based on what I have experienced first-hand from a before/after 396ci LT1 dyno session. I don't mind that you dismiss this as "bad" tuning because I can honestly say that with similar timing, air/fuel, and all fully functioning parts, I have seen first-hand the gains. Sure I would like to see more examples/results, but until then the dyno session I experienced was valid.

You could provide credibility by saying you have tested the same.

 

I have the EFI connection setup on mine. I went this route for really one major reason, but it has added benefits.
1) Tunability. I'm running a fully built 383 with an F1A procharger. It would have been more difficult to find an experienced LT1 tuner to try to handle that. The LS1 PCM is much easier to work with, and a more advanced operating system overall. A simple base tune and 3 dyno pulls later, and I had a really solid tune making huge power.
2) Added benefit: no more opti. Everyone knows on this forum and LTXTech that there are countless threads out there that pertain to optispark issues. Even if your opti is in good shape, but your water pump is leaking, spark issues are soon to follow.
With the LS coils, the ignition system IS more dependable from a standpoint of robust-ness. And, ignition issues can be singled out faster, and the repairs are more than likely less expensive, easier, and would probably occur MUCH less than opti-related repairs.
3) Added benefit: Easier to change and route plug wires and custom remote coil location. I have my coils mounted on my strut bar, so I had to do custom length LS wires. it's much nicer than having to deal with the under-car special-loom setup of the original.
The EFI connection setup is definitely something nice for the LT1 community to have available. I believe one's reasoning for converting is of no consequence, and really isn't anyone's business or basis for judgement.
In my opinion, the EFI connection has the power and capability (unless you're SUPER wild with your setup) to be just as useful as the aftermarket systems, but with the dependability and stability of an OEM product (because essentially, it is). Even if someone just wants to ditch the opti, or "be cool because they have an LS1 computer" is fine. People are free to spend their money how they want in this country.

 

Agreed. Personally, I went through the (unnecessary) expense of a drive by wire system on the TPI in my S10. The throttle cable previously installed (and prom based ECM) worked okay, but for the sake of the hobby, I installed a 4L60E transmission and LS1 Corvette PCM/TAC for modern drivability. Depending on one's view, my project is open for criticism just for having a TPI manifold on top of my engine...or the dated graphics on the side of the truck (ha!)...or the tweed interior...1998 was a looong time ago!

 

Ok so lets see if I can ask this without getting flamed...


If you have a tuned LT1 PCM and switch to the EFI Connection platform with a tune is there anymore power to be made just from the swap???

 

I think you will get all sorts of opinions on that one....as to the merits of idividual coils and complete burns, etc. I doubt it will make much difference myself from a pure HP perspective. Kinda like all the advantages of an aftermarket CD box with multiple sparks, hotter fire, etc. They rarely give more than a couple HP over a good working OEM ignition from real world tests I've seen. High compression ratios and/or forced induction/n2o can have more of a need though. All the above is opinion from someone who has zero experience with the LS conversion so it's all speculation and educated guess. LOL

 

One of my friends who has a mostly stock car.....and runs the stock tune heard about this conversion and got extremely excited. He has had opti issues...switched to delteq and loves it, but I told him about their apparent closing or lack of support at the moment. He is concerned about replacement parts down the road. Anyway....he was very interested in this conversion until he found out that even if he bought all the stuff and installed it....he would then have to find someone who can not only tune the LS1 computer, but also who can tune it for his LT1. I would imagine it's not like you can start with a base tune since there isn't a base lt1 running a ls pcm. Only one local does any tuning that I know of and he can only do OBD1 cars.

 

There are a few differences, but any tuner needs to look at the LT1 and assume it's an LS1. Any good LS tuner can tune an EFI Connection LT1.

 

There is nothing simpler than the LT1 PCM to tune. A capable tuner might have to look Tunercat software over 30 minutes at most to understand it. 30 minutes would be a long time. It's cheap and once you buy it you can tune a bazillion cars with no further costs.

Some don't want to learn anything new, they just want to do the same thing over and over. Just stay in their comfort zone.

The LT1 does not like the same timing & air fuel ratio as an LS1, It would be a dumb mistake to use the same numbers.

 

I've got to agree with Ed, if you are at a point where you need to eliminate the opti then its time to go carbed, but most people will never need to. The only reason to convert would be for tuning convenience. In so cal there are 3 people I know of that tune LT1s, the 2 big LS shops will not touch an LT1. And of the 3 tuners 1 is shady, he refused to tune my car because apparently my 355 is too much for a refreshed tranny with a shift kit and stall. The other 2 know what they are doing. If there was power to be had with this setup, Joe O and Taner Bosnali would have been running these.

 

Back up a few posts...

It's also worth mentioning the many complaints about LT1 distributors. Call it cheap quality optisparks, call it bad installations, call it whatever...there are many problems with the optispark. The LT1 is a good system when everything is working well and there are tuning solutions that get the job done.

I've spent years in the 3rd gen forums and...

...rarely see distributor complaints there.

 

About ready to get this thing cranked up gotta do some odd end stuff first

Anyone have an 02 pcm? I have an 01 truck and 03 vette 411 pcm if anyone wants them or want to trade. I have all the 02 models unlocked on hptuners so an 02 will save me a credit. The vette is a DBW