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93 Chevy OBD1 upgrades?

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93 Chevy OBD1 upgrades?

Postby rookie » Wed Jul 25, 2012 6:25 pm

Yes I searched!
If you know of a thread that covers this, please provide the link!

I am looking to learn what I can about upgrading a 1993 Chevy 350 (SWB single cab PU) Nothing extreme but all info is welcome for future adventures.

First, I am wondering if it is possible to do an adjustable fuel pressure regulator and advance the timing on these?

Second, what is the biggest cam that it will accept with the stock ECU and maybe a chip?...needs to remain fully drivable, dependable and efficient.

Third,What problems may arise from exhaust upgrades? (3/4 header)...is it still possible to get the plug ins for the rear O2 sensors to eliminate Cats?

Forth, How much power can be achieved through Cats (brand or type recommendation?)

Fifth, I fully understand the parts needed (strength wise) for Nitrous, but is there an issue I may encounter with ECU or Cats on the Bottle?

Lay it on me!












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Re: 93 Chevy OBD1 upgrades?

Postby In-Tech » Wed Jul 25, 2012 7:41 pm

rookie wrote:Yes I searched!
If you know of a thread that covers this, please provide the link!

I am looking to learn what I can about upgrading a 1993 Chevy 350 (SWB single cab PU) Nothing extreme but all info is welcome for future adventures.
You didn't say auto or manual, two completely different ecu's and auto ecu has much more availability for adjustment.

First, I am wondering if it is possible to do an adjustable fuel pressure regulator and advance the timing on these?
Yes, chip tuning is better, we'll get back to the regulator in next post.

Second, what is the biggest cam that it will accept with the stock ECU and maybe a chip?...needs to remain fully drivable, dependable and efficient.
It's speed density, so not much cam change will be allowed without ecu work, until next post.

Third,What problems may arise from exhaust upgrades? (3/4 header)...is it still possible to get the plug ins for the rear O2 sensors to eliminate Cats?
There are no rear 02's in OBD1.

Forth, Fourth :wink: How much power can be achieved through Cats (brand or type recommendation?)
Depends on how you treat them, we make over 700 rwhp on the Ford GT's through cats at a reasonable AFR/Labmda .? Alot going on with cat's these days for endurance, whatcha gonna do with it? The occasional burst or bonneville?

Fifth, I fully understand the parts needed (strength wise) for Nitrous, but is there an issue I may encounter with ECU or Cats on the Bottle?
Again, another post as I don't have time at the moment. I do an IAT tricker to retard the timing when nitrous is activated. Of course 93 truck ecu's didn't have IAT so you have to add the pins and alter the ecu program in hex in the chips' binary file as I don't believe anyone has software that exploits this in that year. Basically on these as well as many late model ucu's in non nitrous state the IAT is normal, when active I built a small circuit that tells the ecu(via small signal relay and resistor) that the IAT is now way hotter(can't remember off top of head, me thinks I use a 170 ohm resistor(~220F), would have to look at notes) and now in that part of the IAT table I adjust the timing as well as can do some fueling in some of the ecu's. Wet or dry most times I can get it perfect [-o<

Lay it on me!


Laid :lol:
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Re: 93 Chevy OBD1 upgrades?

Postby rookie » Wed Jul 25, 2012 9:54 pm

In-Tech, thanks I haven’t been Laid in a while so you were wonderful….I Think?

Stock automatic…some say 700 r4 and some say 4L60…not sure.

This is a daily driver back up so I don’t need anything extreme, maybe a rocker ratio increase or cam if there is a better option over stock.

I don’t mind sticking with Cats or Cat if single exhaust is enough…500 to 600 at the fly wheel is more than I would need on the bottle, strong, dependable and efficient off the bottle is fine.

Nitrous shot would be small and maybe progressive if need be…75 to 150 shot max.

Thanks again for any advice you can give me…
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Re: 93 Chevy OBD1 upgrades?

Postby In-Tech » Thu Jul 26, 2012 12:04 pm

rookie wrote:In-Tech, thanks I haven’t been Laid in a while so you were wonderful….I Think?

Stock automatic…some say 700 r4 and some say 4L60…not sure.
It should be a 4L60E, look at the computer behind the glove box, it should have a red and a blue connector.

This is a daily driver back up so I don’t need anything extreme, maybe a rocker ratio increase or cam if there is a better option over stock.
If you're lucky your block will already be machined for factory hyd roller even though there is a flat tappet cam in it. I had some custom lobes made years ago that are 222/226 @.050 with VERY short seat duration that I use for this application. The cam is ground on a 116 LC and is actually in the catalog now at Erson Cams. It idles like a stocker but yields excellent power, driveability and mpg.

I don’t mind sticking with Cats or Cat if single exhaust is enough…500 to 600 at the fly wheel is more than I would need on the bottle, strong, dependable and efficient off the bottle is fine.
Shorty headers and a 3" cat back system is fine. 500 hp is doable with a 150 shot, however, you will need some vortec heads, GM intake 12496821, 454 TBI and injectors with fuel pressure cranked up to 30 psi vs stock 12 psi in order to get enough fuel through those 2 injectors. A different fuel pump is also needed and I usually use the syclone/typhoon pump. The factory monolithic cat should be fine if in good shape. Now with all of this you will definitely have to reprogram the chip in the ecu, a project not for the faint of heart but all doable.

Nitrous shot would be small and maybe progressive if need be…75 to 150 shot max.
It will have to be a "wet" system as you can't get enough fuel through the 454 injectors to make 500 fwhp.

Thanks again for any advice you can give me…


No problem, hope this info adds insight.
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Re: 93 Chevy OBD1 upgrades?

Postby In-Tech » Thu Jul 26, 2012 12:21 pm

p.s. The stock high swirl heads, intake and TB don't have a prayer of making any real hp. I just wanted to clarify that. That engine stock only had 210 hp.
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Re: 93 Chevy OBD1 upgrades?

Postby rookie » Thu Jul 26, 2012 2:17 pm

In-Tech wrote:
rookie wrote:In-Tech, thanks I haven’t been Laid in a while so you were wonderful….I Think?

Stock automatic…some say 700 r4 and some say 4L60…not sure.
It should be a 4L60E, look at the computer behind the glove box, it should have a red and a blue connector.

This is a daily driver back up so I don’t need anything extreme, maybe a rocker ratio increase or cam if there is a better option over stock.
If you're lucky your block will already be machined for factory hyd roller even though there is a flat tappet cam in it. I had some custom lobes made years ago that are 222/226 @.050 with VERY short seat duration that I use for this application. The cam is ground on a 116 LC and is actually in the catalog now at Erson Cams. It idles like a stocker but yields excellent power, driveability and mpg.

I don’t mind sticking with Cats or Cat if single exhaust is enough…500 to 600 at the fly wheel is more than I would need on the bottle, strong, dependable and efficient off the bottle is fine.
Shorty headers and a 3" cat back system is fine. 500 hp is doable with a 150 shot, however, you will need some vortec heads, GM intake 12496821, 454 TBI and injectors with fuel pressure cranked up to 30 psi vs stock 12 psi in order to get enough fuel through those 2 injectors. A different fuel pump is also needed and I usually use the syclone/typhoon pump. The factory monolithic cat should be fine if in good shape. Now with all of this you will definitely have to reprogram the chip in the ecu, a project not for the faint of heart but all doable.

Nitrous shot would be small and maybe progressive if need be…75 to 150 shot max.
It will have to be a "wet" system as you can't get enough fuel through the 454 injectors to make 500 fwhp.

Thanks again for any advice you can give me…


No problem, hope this info adds insight.

This is exactly what I was looking for, I was thinking about the Vortec upgrade last night I know Pace and Scoggins sale these.

The wet system is what I have ran on my race cars for years so thats not a problem.

The factory exhaust has been replaced so I have know idea what is on it, but I can build what ever is needed.

Syclone/Typhoon pump, I am guessing will work in the stock tank, and I would probably use the Syclone/Typhoon pressure regulator as well?

Any special attention needed for the 454 TBI?

Do you reprogram Chips, or do you have someone you recommend?
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Re: 93 Chevy OBD1 upgrades?

Postby Orr89rocz » Thu Jul 26, 2012 2:23 pm

If those systems are anything like the thirdgen camaro TBI systems, then there is good support over at thirdgen.org for tuning. Can get equipment at moates.net. I never messed with TBI stuff but the TPI stuff I play with a good bit and its not all that hard to do. Kinda cheap too
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Re: 93 Chevy OBD1 upgrades?

Postby rookie » Thu Jul 26, 2012 3:01 pm

In-Tech, do you think it would be worth it to step up to the new bigger Iron 185's or Aluminum 210's version (kind of big) of Vortecs?

Or what about after market Vortecs, I have a connection with EQ

Or would I be better off just going with after market heads, intake and getting an after market EFI system?

I already have several sets of EQ and RHS heads and and Air Gap along other Intakes, so all I would have to buy would be the EFI.
Last edited by rookie on Thu Jul 26, 2012 3:21 pm, edited 4 times in total.
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Re: 93 Chevy OBD1 upgrades?

Postby rookie » Thu Jul 26, 2012 3:03 pm

Orr89rocz wrote:If those systems are anything like the thirdgen camaro TBI systems, then there is good support over at thirdgen.org for tuning. Can get equipment at moates.net. I never messed with TBI stuff but the TPI stuff I play with a good bit and its not all that hard to do. Kinda cheap too

I'll ck that out, Thanks
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Re: 93 Chevy OBD1 upgrades?

Postby ap72 » Thu Jul 26, 2012 3:27 pm

Any particular reason you're willing to change all of that but not the factory computer?
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Re: 93 Chevy OBD1 upgrades?

Postby rookie » Thu Jul 26, 2012 3:37 pm

ap72 wrote:Any particular reason you're willing to change all of that but not the factory computer?

No I am not apposed to upgrading as needed, I am just looking at what all is possible with the factory stuff and at what point is it better to just go complete after market?

If I can adjust timing and fuel pressure with what I have and do an exhaust upgrade for now then I would opt for that, for now.

But if I get to where I need heads, cam and intake then if I can use what I already have and convert to an after market EFI I would go that way.

Just trying to see what options I have.
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Re: 93 Chevy OBD1 upgrades?

Postby crazyman » Thu Jul 26, 2012 4:13 pm

An easy, cheap, seat of the pants improvement would be the same vintage 305 heads. No muss, no fuss. The smaller ports might increase the vacuum enough to get away with some cam.
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Re: 93 Chevy OBD1 upgrades?

Postby In-Tech » Thu Jul 26, 2012 4:20 pm

The sy/ty pump will drop right in, you still use the TBI regulator. The deal with the 454 TB's can be a bit confusing, up to 93 they had ~2" Blade and 2-75lb injectors at 12 psi, tps different than yours but IAC the same, 94-95 454 tb's have ~2" blades and 2-75 lb injectors but 75lb @ 30 psi and tps matches your but has newer IAC, Just need to match up the connectors when it's time. What I used to do was junkyard a 94-95 TBI unit and go buy early 454 injectors as I don't trust junkyard injectors. That way you end up with a 30lb regulator. Or if you find a super deal on the early one, just buy a 30lb regulator from GM and have the injectors cleaned. Keep in mind those aftermarket adjustable regulator "caps" cannot adjust from 12 psi to 30 psi as the spring is different and the 12 psi spring will not go that high until coil bind [-X

Yes I do re-programming of stock ecu's as well as many many aftermarket controllers, but never mail order. You're going to want someone hands on to do the tuning or buy the stuff to do it yourself, it's not all that costly or hard and as mentioned, thirdgen.org and moates.net are great places to read and check what your up against.

The intake/TBI is your limiting factor so a bigger head won't do much for you if at all. I've not used any EQ vortec heads but if they flow equivalent to stock and are cheap, use them.

If you go aftermarket ecu you've got the price of an ecu, a harness to make and also need an ecu for the trans, not so cost effective when the stock one will do EVERYTHING you need to do. You can even put a 4bl type efi manifold on it, add to the harness for the extra injectors(Batch fire), set the setting in the chip for PFI instead of TBI and tune. You've got alot of options. Any questions just ask, I've been tuning EFI since almost it's beginning. :)
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Re: 93 Chevy OBD1 upgrades?

Postby rookie » Fri Jul 27, 2012 12:31 pm

Just a thaught, what if I did just the Vortec Heads, Intake and maybe a 1.6 ratio rocker, would the stock tune work...or maybe a chip?
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Re: 93 Chevy OBD1 upgrades?

Postby In-Tech » Sat Jul 28, 2012 2:57 am

I guess we're done here. There is a huge difference between mass air flow tuning and speed/density which is what you have. You can't change anything that alters the VE of a speed density tune and expect the ecu to keep up. You can make small changes and the ecu can keep up, what you are suggesting is impossible.
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