LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Install EFI connection LSX PCM

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Old 07-11-2011, 03:37 PM
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Originally Posted by jrock692
Okay we have the debate on weather or not the ls1 setup will make more hp over the lt1 do to the ls1 setup being morfe precise. But my questikon is this wouldn't the big hp be from the ls1 pcm being able to support higher rpms? I think I have read that you can spin higher on an ls1 right? And you always hear the pcm is a limit in making hp on the top end. How many rpms will the ls1 support? And how much more hp are you talking about gaining in that rpm range over the lt1 pcm?
If you have a radically modified LT1 that needs to spin 7000+ rpms, it will be limited to the stock pcm capability, which I think 7000-7200 rpms. Now, if you have a motor thats stays under these rpms, why waste money on the LS conversion? The optispark will be your weakest ignition link.

The LS1 pcm on the other hand can be tuned to 8000+ rpms, as long as you have the motor combination that can make power and handle the higher end.

Stock for stock LT1/LS1 pcms, no horsepower difference.IMO.
Old 07-11-2011, 06:50 PM
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O I agree that stock for stock you wouldn't really see much if any, assuming both systems are working properly. I'm just saying there could be more HP to be made on the top end! And ask the question how much more HP can you get outta the extra rpms? And I'm not talking about on a stock setup.
Old 07-11-2011, 10:21 PM
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Reasons I like the conversion is of course no more opti crap, I absolutely love HP Tuners, they have a great user friendly forum, and I am actually tuning my own car now and its not to bad (mods in sig).

As far as more power from a LT1/LS1 computer, who knows, but the 411 LS1ECU is awesome. I just upgraded to a 2 BAR SD Custom OS with RTT. ITs awesome

Not too many people tuning LT1's anymore, and there will be even less in the future IMO.
Old 07-12-2011, 09:24 AM
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We've been seeing consistent horspower and torque increases throughout the RPMs when comparing LT1 PCM to LS1 PCM on LT1 engines. These numbers are not staggering, but the conclusions we are coming up with (and feedback from other tuners) is that the increases are due to ignition timing accuracy (the LS1 PCM fires injectors and coils based on crank position). Having dyno'd several 24x LT1 engines (350ci thru 396ci) TPIS is suggesting that the gains are more noticeable with engines that have higher cylinder pressures.

The November 2011 issue of Car Craft will have a writeup on this. The engine in this article is a 383 LT1 and demonstrates an LT1 PCM and LS1 PCM comparison.
Old 07-12-2011, 10:19 AM
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Originally Posted by S10Wildside
We've been seeing consistent horspower and torque increases throughout the RPMs when comparing LT1 PCM to LS1 PCM on LT1 engines. These numbers are not staggering, but the conclusions we are coming up with (and feedback from other tuners) is that the increases are due to ignition timing accuracy (the LS1 PCM fires injectors and coils based on crank position). Having dyno'd several 24x LT1 engines (350ci thru 396ci) TPIS is suggesting that the gains are more noticeable with engines that have higher cylinder pressures.

The November 2011 issue of Car Craft will have a writeup on this. The engine in this article is a 383 LT1 and demonstrates an LT1 PCM and LS1 PCM comparison.
congrats on the recognition of your hard work in the magazine Mike and for doing this for the LT1 crowd to create an option.
Old 07-12-2011, 11:06 AM
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Originally Posted by merim123
congrats on the recognition of your hard work in the magazine Mike and for doing this for the LT1 crowd to create an option.
Thank you for the kind remarks. Mark really gets the credit for the LT1 conversion. I originally had little intentions on moving forward with LT1 support.
Old 07-12-2011, 12:16 PM
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Originally Posted by S10Wildside
We've been seeing consistent horspower and torque increases throughout the RPMs when comparing LT1 PCM to LS1 PCM on LT1 engines. These numbers are not staggering, but the conclusions we are coming up with (and feedback from other tuners) is that the increases are due to ignition timing accuracy (the LS1 PCM fires injectors and coils based on crank position). Having dyno'd several 24x LT1 engines (350ci thru 396ci) TPIS is suggesting that the gains are more noticeable with engines that have higher cylinder pressures.

The November 2011 issue of Car Craft will have a writeup on this. The engine in this article is a 383 LT1 and demonstrates an LT1 PCM and LS1 PCM comparison.
I'd back that up also. I haven't done a before and after but a ton of LT1s we have come threw the shop will have ignition problems over 6500 RPM. You might not hear it on the street but it shows up on the dyno. The ls1 controllers are much easier to get a better result with.
Old 07-12-2011, 03:20 PM
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Originally Posted by merim123
congrats on the recognition of your hard work in the magazine Mike and for doing this for the LT1 crowd to create an option.
I second that. Thanks for the great option for LT1 ignition and tunability. I couldn't be happier.
Old 07-12-2011, 09:38 PM
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Tis the only reason i did the swap. Rid of the opti and be able to tune it myself/ better . My car is only going to be heads/cam, full bolts on at the most only spinning to 6 grand roughly.

The option is there later if i want it so, woo for eficonnection
Old 07-12-2011, 10:16 PM
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Originally Posted by qc97z
I second that. Thanks for the great option for LT1 ignition and tunability. I couldn't be happier.
x2. Great product and awesome results.
Old 07-13-2011, 07:01 AM
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Getting ready to start my conversion. Lost interest in the car for a few years. Looking forward to a better running setup. Better springs and pushrods will be done at the same time. Hoping to knock off a few more tenths. Times in my sig were ran with 6300 RPM shift points. Looking forward to shifting closer to 6800 without the breakup I seem to get whenever the opti gets a little tired. Haters stay away. I,ve been thru 4 optis in 7 years. Not gonna spend the cash on another one. Wish me luck.

Mec
Old 08-02-2011, 10:56 PM
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Lets talk grounding! how is everyone grounding there DIY harnesses? right now I think I have something dropping out. It wont fire everytime and when it does it will run rough and then loose all throttle response within a few seconds like if you left VATS on. I have all the grounds shown in the wiring diagrams broken out individually and then combined into one point at a ground distribution block and then 0 gauge wire that runs straight to the battery in the rear...
Old 08-03-2011, 04:23 AM
  #273  
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Originally Posted by Tricked-Out-Toy
Lets talk grounding! how is everyone grounding there DIY harnesses? right now I think I have something dropping out. It wont fire everytime and when it does it will run rough and then loose all throttle response within a few seconds like if you left VATS on. I have all the grounds shown in the wiring diagrams broken out individually and then combined into one point at a ground distribution block and then 0 gauge wire that runs straight to the battery in the rear...
Ignition issues are commonly related to an incorrect crank reluctor install. Intermittent ignition issues are typically a loose crank reluctor (crank bolt is too long, not tight, or the crank hub is not flat).

I would recommend wiring the sensor grounds just like and LS1 harness. I'm not convinced this is required, but have never done it any other way.
Old 08-03-2011, 08:54 PM
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Just got mine up and running on a DIY harness, aside from a really shakey tune things seem to be working great. Getting all the details sorted out now... gets better every time we drive it and all i can say is awesome product guys!
Old 09-17-2011, 11:07 PM
  #275  
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Originally Posted by Ed Wright
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?
I guess that whoever believes in your mail order tunes also believe in unicorns and tooth fairies.

I guess you would say the same thing against an E38 right?

And of course... I wouldn't think that you feel that the scantools available for the LT1 are up to the task as the ls1 scantools available right? That alone is worth upgrading the ECU. Heck that alone is worth getting an E38 over the LS1. But to each its own.
Old 09-19-2011, 07:55 AM
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Cant wait to start my project with the DIY harness. Still tracking down the last of my parts needed.
Old 09-19-2011, 01:21 PM
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Same here... Ive got the 97 cover, a bid on a harness, and was the top bidder on a set of truck coils with harness and brackets for $25 but some fugger outbid me by $1 at the last minute...
Old 05-07-2012, 07:59 PM
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whats the part number for a double roller 24x reluctor?

Last edited by robsquikz28; 05-07-2012 at 08:29 PM.
Old 05-14-2012, 12:13 AM
  #279  
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Not sure if this has been answered before but here it goes.
My question is, can you doubt the tuner even though he says he can do it and has had experience tuning the LS1 pcm's but never done the Efi conversion on an LT1 before? My tuner guy is supposedly good around the area we shall see but he's never done the conversion before, should I be worried? Long story short, I took the car for dyno tuning he didn't finish because I wasn't happy with my setup so I changed it. It seems to run pretty good considering that he is not done tuning it. But my gauge rpm's are not correct with the actual engine speed and when I took it down the road and back I got a check engine light indicating a no #2 knock sensor which I'm running the single knock sensor that I bought new from Gm 1997 knock sensor. Everything else seems to be done away with as far as evap, egr, rear o2s, etc. Right now I'm giving him the benefit of the doubt. I am scheduled in for Final tuning 5/26/12 so until he tells me he is done with it I can't say nothing bad about the conversion or my tuner.



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