extensive mods and emissions PART 2
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extensive mods and emissions PART 2
Although I was satisfied with the anwers to my general (vague) question on 10/25 about extensive modifications and emissions, I've gotten more curious about the issue. I've tried to make the following questions specific:
Assume the car is a 1988 with a 4+3 transmission that meets the federal emission standards for 1988. From what I know, if I install a K+N air filter assembly, remove the MAF screens, and install a cat-back exhaust the stock PROM will handle the changes and the car will maintain stock driveability and the federal emission standards for 1988. If, however, I pocket port the heads and try a three angle valve job, I assume that I will need to reprogram the chip in order to maintain stock emissions and driveability. If I then add long tube headers, I am guessing that I will have to do more reprogramming in order to maintain stock emissions and driveability. At what level of modification will it become impossible to maintain stock emissions and driveability regardless of the quality of the reprogramming (I know that a radical cam will cause problems)?
David
Assume the car is a 1988 with a 4+3 transmission that meets the federal emission standards for 1988. From what I know, if I install a K+N air filter assembly, remove the MAF screens, and install a cat-back exhaust the stock PROM will handle the changes and the car will maintain stock driveability and the federal emission standards for 1988. If, however, I pocket port the heads and try a three angle valve job, I assume that I will need to reprogram the chip in order to maintain stock emissions and driveability. If I then add long tube headers, I am guessing that I will have to do more reprogramming in order to maintain stock emissions and driveability. At what level of modification will it become impossible to maintain stock emissions and driveability regardless of the quality of the reprogramming (I know that a radical cam will cause problems)?
David
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From: SE NY
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Re: extensive mods and emissions PART 2 (DSKRALL)
So long as you stay with a "decent" cam (i.e. not too much overlap) you can do cam, heads, intake, exhaust (rataining a hi-flow cat), coolant temp change and such and be able to "tune" it with an AFPR to be very streetable and pass emissions testing (with the possible exception of visual checks) while running the stock chip.
With my current mods and using the stock chip my L98 easily passes OH dyno emissions testing.
I hope to be able to do the head, cam and maybe headers soon and will only consider a custom chip for tuning fuel & timing to the nth degree.
With my current mods and using the stock chip my L98 easily passes OH dyno emissions testing.
I hope to be able to do the head, cam and maybe headers soon and will only consider a custom chip for tuning fuel & timing to the nth degree.
Thread Starter
Instructor
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Re: extensive mods and emissions PART 2 (65Z01)
65Z01: Thank you for your reply. I am impressed with the capability of the stock programming. How many of those modifications could be made to an L98 with a speed density set up while still meeting federal emissions standards (I'm guessing not nearly as many)?
David
David
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From: Athens AL
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Re: extensive mods and emissions PART 2 (DSKRALL)
You wouldnt need to reprogram the chip with the first set of mods, no.
You would probably not need to reprogram after portwork. A cam change, yes.
You may need a reprogram if doing just the headers, but the L98 can pass the sniffer in most states without its precats in the front Y, so you probably do not need a chip reprogram.
But, you should pass emissions with almost anything done to it, so long as the cam is the same, with the stock chip.
You would probably not need to reprogram after portwork. A cam change, yes.
You may need a reprogram if doing just the headers, but the L98 can pass the sniffer in most states without its precats in the front Y, so you probably do not need a chip reprogram.
But, you should pass emissions with almost anything done to it, so long as the cam is the same, with the stock chip.
Burning Brakes
Joined: Jan 2001
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From: Manhattan
Re: extensive mods and emissions PART 2 (vader86)
I have a '90 L98 SD. I haven't had to get the emissions checked, but I am not planning any future mods without learning how to program the chip.
I have the free mods done, k&n, air pump eliminator kit, hedman 1 5/8" headers, 3" dual exhaust and an AFPR.
The next mods would be a new intake and cam, and I feel the current mods I have are about as far as i'd like to go without a custom chip. I'm not worried about problems with the few mods i have on the stock chip, but I believe I might pick up a couple hp and mpg's.
--steve
I have the free mods done, k&n, air pump eliminator kit, hedman 1 5/8" headers, 3" dual exhaust and an AFPR.
The next mods would be a new intake and cam, and I feel the current mods I have are about as far as i'd like to go without a custom chip. I'm not worried about problems with the few mods i have on the stock chip, but I believe I might pick up a couple hp and mpg's.
--steve
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Re: extensive mods and emissions PART 2 (Raistlin)
Thanks for the replies to my question about L98 speed density systems. I have been told by Lingenfelter's that a speed density set up will handle, roughly, a 15% boost in airflow while retaining the stock chip, stock emissions, and stock driveability. I didn't think that 15% would allow for many modifications, but you are listing more than I thought possible.
David
David
