Non-Thirdgen....more LT1 stuff
01-26-2003, 07:18 PM
#1
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Car: 1987 Trans Am
Engine: LT1
Transmission: T-56
Axle/Gears: 10 Bolt SLP Torsen, 3.73 ratio
Non-Thirdgen....more LT1 stuff
I read that the LT1 gets EGR gas from a "external source" I would be guessing they meant something other than the manifold? If so, where? Right now I have SLP 1 3/4 headers on the car. If I have to get rid of them it will probably be a deal breaker....Unfortunatly I need my emissions crap here...they started stricter emmissions, and with a possible move to the Arlington TX area, I think they get worse there...so I need to be able to beat the sniffer.
01-26-2003, 11:55 PM
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Car: 1987 Trans Am
Engine: LT1
Transmission: T-56
Axle/Gears: 10 Bolt SLP Torsen, 3.73 ratio
OK, got it, internal EGR uses the cam timing. External grabs it from the heads and the valve sits on the intake like normal. The LT4 had the internal style EGR from what I can tell.
01-27-2003, 01:24 AM
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Car: 84 Z-28 Camaro
Engine: 383
Transmission: T-56
Axle/Gears: richmond 3.73, eaton posi
I think the new small blocks(LS1 ect.) have their EGR set up kinda like a f*rd- a tube runs between the two exauast manifolds and a tube runs off of that to an EGR valve on the intake manifold, the new engines have no crossover in the heads/intake for a regular EGR to run off of.
01-27-2003, 11:09 AM
#4
Corry,
I mentioned it in your other LT1 thread, but there was a lot of stuff there, so you might have missed it.
The LT1 family used a stainless accordion tube from the rear of the right exhaust manifold to supply exhaust gasses to the EGR valve (on the back of the intake). You can either weld a bung/fitting on your headers to make this supply connection, or use the cast iron manifolds from the LT1 for exhaust. I'm guessing that you want to keep the SLP headers, so you'll need some sort of supply connection.
The only exception to this was in that the LT4 "Hot" cammed engines eliminated the need for an EGR system by using a cam profile with a lot of overlap (from a late-closing exhast ramp), thereby leaving some exhaust gas in the chambers from the previous cycle. Basically, they killed some of the scavenging at lower RPMs and exhaust system velocities. However, the system required the LT4 PCM to control the individual cylinder fuel rates and ignition timings and monitor the four O² sensors to be able to meet emissions and operate the engine satisfactorily. A PCM programmed to operate an LT1 ("P" engine) won't be able to do that without an EGR system.
If you need to meet emissions requirements, you'll probably need the EGR system, since they will be looking for it in the visual portion of the inspection. If all you have to do is blow a clean sniffer on the treadmill, you might get by with the LT4 scheme if you use the entire LT4 contol system.
I mentioned it in your other LT1 thread, but there was a lot of stuff there, so you might have missed it.
The LT1 family used a stainless accordion tube from the rear of the right exhaust manifold to supply exhaust gasses to the EGR valve (on the back of the intake). You can either weld a bung/fitting on your headers to make this supply connection, or use the cast iron manifolds from the LT1 for exhaust. I'm guessing that you want to keep the SLP headers, so you'll need some sort of supply connection.
The only exception to this was in that the LT4 "Hot" cammed engines eliminated the need for an EGR system by using a cam profile with a lot of overlap (from a late-closing exhast ramp), thereby leaving some exhaust gas in the chambers from the previous cycle. Basically, they killed some of the scavenging at lower RPMs and exhaust system velocities. However, the system required the LT4 PCM to control the individual cylinder fuel rates and ignition timings and monitor the four O² sensors to be able to meet emissions and operate the engine satisfactorily. A PCM programmed to operate an LT1 ("P" engine) won't be able to do that without an EGR system.
If you need to meet emissions requirements, you'll probably need the EGR system, since they will be looking for it in the visual portion of the inspection. If all you have to do is blow a clean sniffer on the treadmill, you might get by with the LT4 scheme if you use the entire LT4 contol system.
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