LTX and LSXPutting LT1's, LS1's, and their variants into Third Gens is becoming more popular. This board is for those who are doing and have done the swaps so they can discuss all of their technical aspects, including repairs, swap info, and performance upgrades.
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I've been thinking about converting a LT1 I have for use with a small cap HEI distributor, completely doing away with the opti-spark and all associated parts, and basically doing this swap with a stand alone TPI harness and factory ECM.
Will this work? If you were to rid the LT1 of it's standard ignition system for a HEI distibutor, and tune a chip to work with a LT1, what would be to stop this swap from being possible? I will also run this motor without a MAF sensor, and the transmission will be a 200-4r, so I'm not worried about losing a PCM controlled transmission.
If you do a TPI to LT1 intake conversion can you reuse your existing TPI harness with little to no modifications? If so what's to keep a LT1 from running as well as a TPI to LT1 intake converterd Gen I SBC? Wouldn't the two engines be pretty much the same (electronically) if there was no opti spark?
I know this isn't exactly considered "progress" but I really don't want another LT1 swapped car with a opti spark. This engine will be going in a '86 Regal in place of the original Olds 307 FWIW.
I've already searched, but couldn't find anything that was of much help, so let me know your thoughts and opinions. Thanks.
Optispark had one avoidable weakness that has earned it a bum reputation.
TPI is batchfire vs. the LT1 sequential injection. That alone will cost you low end and economy.
There's the cost of getting the LT1 intake properly modified for the distributor. You'd have the benefits of the better head design and the reverse flow cooling, but other than that, you'd basically have a Miniram'd TPI (a Vortec-headed Miniram TPI would do as well).
Seems to me to be a high price to pay just for the sake of being "different". If your LT1 doesn't include harness or PCM, it would cost less to get those from eBay or craigslist. And, the PCM would be easier to program than the TPI ECM.
Well, the one thing that comes immediately to mind is the lack of any provision for a distributor in the LT1 block. It's possible that you could just drill/machine down in the correct location, but given the fact that those engines have the reverse-cooling, it's also possible that it the "distributor shaft passage" could go into a cooling jacket. Might be worthwhile to get one of the 4.3 blocks to test with first.
Its probably possible but its like taking a step backward in technology. One thing I really like about the opti is that you do not have to adjust the timing like you would with a regular dist.
If you are looking into getting rid of the opti completely, the better way is with an aftermarket computer and coil packs.
Well, the one thing that comes immediately to mind is the lack of any provision for a distributor in the LT1 block. It's possible that you could just drill/machine down in the correct location, but given the fact that those engines have the reverse-cooling, it's also possible that it the "distributor shaft passage" could go into a cooling jacket. Might be worthwhile to get one of the 4.3 blocks to test with first.
It's an interesting idea...
This is actually incorrect. There is the location for the distributor in the block, it just has a plug that bolts in to keep the oil pump shaft from coming out of the oil pump (it uses the same pump as a Gen 1 and is gear driven from the end of the cam).
But I agree with the above people, changing the items over would destroy what is best about the LT1. It would be cheaper just going with an L98 if you wanted to keep the TPI and rear mounted distributor.
BTW....I am still running the same opti in my '95 model motor with over 150k miles on it.
There is the location for the distributor in the block, it just has a plug that bolts in to keep the oil pump shaft from coming out of the oil pump (it uses the same pump as a Gen 1 and is gear driven from the end of the cam).
Good to know, thanks. I guess that the LT-series engines are less of an "evolution" than I'd thought...
Optispark had one avoidable weakness that has earned it a bum reputation.
TPI is batchfire vs. the LT1 sequential injection. That alone will cost you low end and economy.
How much low end are we talking about losing? I was planning on swapping in a Crane 227 cam, or maybe a GM 846 cam as well as porting the stock (aluminum) heads/intake. How much power do you think I'll lose with those mods due to the batchfire injection?
Quote:
Originally Posted by five7kid
There's the cost of getting the LT1 intake properly modified for the distributor. You'd have the benefits of the better head design and the reverse flow cooling, but other than that, you'd basically have a Miniram'd TPI (a Vortec-headed Miniram TPI would do as well).
Seems to me to be a high price to pay just for the sake of being "different". If your LT1 doesn't include harness or PCM, it would cost less to get those from eBay or craigslist. And, the PCM would be easier to program than the TPI ECM.
Well, it's not so much that I want to be different, even though I do have a spare B-body engine harness and PCM sitting around. I'm just tired of being afraid to wash under the hood of the LT1 cars that I have and have had (I've learned my lesson.) I also prefer the ability to adjust the timing with a timing light, even though I know the PCM is far better at controlling the timing, but it's a tradeoff that I'm willing to accept. Different IMO would be building and installing a small block Buick with standalone EFI, which is what I really want for this car, but it's just not affordable for me right now. But I do get really tired of seeing Buicks and Oldsmobiles with Chevy motors. However, I have a couple of aluminum head LT1 engines sitting around as well as a good small cap HEI distributor, and I should have a ECM somewhere as well. I was thinking about going with one of the standalone TPI harnesses that are sold on Ebay for about $200, and I would have the intake done by LT1intake.com. I would imagine it wouldn't be any more difficult to tune a cammed ECM controlled LT1 than it would be to tune a cammed TPI... right?
Thanks for the replies everyone, keep them coming... I'm open to opinions.
I'm just tired of being afraid to wash under the hood of the LT1 cars that I have and have had (I've learned my lesson.)
I wash mine 2-3 times a year, still no problems with it, now if you had a '94 with a non-vented opti, I would understand...the vented opti fixed alot of the moisture problems and the MSD unit is really nice.
TPI will only spin up to about 5300 RPM and then just goes flat, where the LT1's can go to 7k with a ported stock intake.
I wash mine 2-3 times a year, still no problems with it, now if you had a '94 with a non-vented opti, I would understand...the vented opti fixed alot of the moisture problems and the MSD unit is really nice.
TPI will only spin up to about 5300 RPM and then just goes flat, where the LT1's can go to 7k with a ported stock intake.
I've had to replace a vented opti in the past due to moisture after a wash. I don't really want to chance that again. The only problem I have with the MSD unit is the cost of it.
What's the highest allowable RPM you can go with a stock TPI ECM?
) I also prefer the ability to adjust the timing with a timing light, even though I know the PCM is far better at controlling the timing, but it's a tradeoff that I'm willing to accept. Different IMO would be building and installing a small block Buick with standalone EFI, which is what I really want for this car, but it's just not affordable for me right now. But I do get really tired of seeing Buicks and Oldsmobiles with Chevy motors. However, I have a couple of aluminum head LT1 engines sitting around as well as a good small cap HEI distributor, and I should have a ECM somewhere as well. I was thinking about going with one of the standalone TPI harnesses that are sold on Ebay for about $200, and I would have the intake done by LT1intake.com. I would imagine it wouldn't be any more difficult to tune a cammed ECM controlled LT1 than it would be to tune a cammed TPI... right?
