LT4 Improvements
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Joined: Mar 2011
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Okay, here's my tentative list in order of completion:
1) Replace optispark (stock?)
2) Open lid air box
3) shorty headers and a cat back exhaust (corsa?)
4) Electric Water pump
5) Hot cam
6) Port and Polish heads and intake (using our machine shop)
Before I changed the plugs wires and air filter (black), I ran an 8.72 (2.5 60ft) in the 8th mile at 83 mph. That was 2 tenths quicker than 2 GTO's and an SRT-8 Challenger that were running on the same night. The car's temp kept creeping up too, so I imagine it'll run a bit quicker when I get the temp down.
I should have all of this completed by the end of the summer. It's bass fishing season so I'll be out on the lake on my only off days.
1) Replace optispark (stock?)
2) Open lid air box
3) shorty headers and a cat back exhaust (corsa?)
4) Electric Water pump
5) Hot cam
6) Port and Polish heads and intake (using our machine shop)
Before I changed the plugs wires and air filter (black), I ran an 8.72 (2.5 60ft) in the 8th mile at 83 mph. That was 2 tenths quicker than 2 GTO's and an SRT-8 Challenger that were running on the same night. The car's temp kept creeping up too, so I imagine it'll run a bit quicker when I get the temp down.
I should have all of this completed by the end of the summer. It's bass fishing season so I'll be out on the lake on my only off days.
Racer
Joined: Jan 2007
Posts: 380
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From: Toronto Ontario
I've been watching this thread with interest. Recently bought a low mileage LT4 that is running great and I promised myself that I would leave well enough alone and then this thread comes along and gets me thinking that maybe a little tinkering wouldn't be so bad, would it? I either get off this forum or I kindly request that when you get around to your mods (after fishing) you keep us posted as you get your mods done. A before and after dyno would be great. I will probably end going down the same path as you but think I will wait as the opti and/or water pump come up for replacement. Maybe start accumulating some parts and look at a winter project (not sure which winter yet). Good luck. Peter
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I'll keep you posted. I plan on getting the opti, waterpump and airbox done within the month. The Headers and exhaust done by the middle of June. Like you, I didn't want to do much to it, just some minor basics.
My measurements will have to be more in ET's than dyno numbers. Truthfully, I just can't be bothered with finding a reliable dyno technician and then setting aside time to get it done. I'd much rather just go to the track.
My measurements will have to be more in ET's than dyno numbers. Truthfully, I just can't be bothered with finding a reliable dyno technician and then setting aside time to get it done. I'd much rather just go to the track.
Melting Slicks
Joined: Jan 2009
Posts: 3,482
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From: folsom california
Have an LT4; can't say all Flowmaster systems are bad; the ones that retain the resonator and use three chamber mufflers are probably a completely different animal from the flowmater system on my car: no resonator and shortly style two chamber mufflers which ...well words fail to describe how bad it was.
relpaced it with a corsa exhaust system...expensive ... but no regrets, the corsa is superb.
want (need?) to make an LT4 go faster ? do what the factory did: jnstall an LT4 Hot Cam; Its a drop in no brainer: works with the stock computer and breezes through CA smog. Sounds great through a corsa exhaust too.
relpaced it with a corsa exhaust system...expensive ... but no regrets, the corsa is superb.
want (need?) to make an LT4 go faster ? do what the factory did: jnstall an LT4 Hot Cam; Its a drop in no brainer: works with the stock computer and breezes through CA smog. Sounds great through a corsa exhaust too.
Thread Starter
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I went with the Magnaflow cat back system, minus the resonator. It is on the way right now.
I'm going to do the electric water pump, optispark and possibly an underdrive pulley next.
One question about the pulley: Will the March Pulley that was made for the LT1 work on the LT4? I'm getting conflicting info on this.
I'm going to do the electric water pump, optispark and possibly an underdrive pulley next.
One question about the pulley: Will the March Pulley that was made for the LT1 work on the LT4? I'm getting conflicting info on this.
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Interesting. I can get one for $50, but it came off of an LT1. Not sure if it works on the LT4. For $50, I would be willing to experiment with it (since I'm going to be working on that area of the engine anyway), but I wouldn't for $300.
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Drifting
Joined: Oct 2005
Posts: 1,913
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From: Angier nc
I would'nt waste the money on shorty headers.Save that cash for some long tube headers and bullet cats down the road.
You may want to rethink the no resonator.Drive it and see if you have the annoying resonance at any cruise rpm's.
Make sure you replace the valve springs when you do the cam.
Get your mods done(all of them) and find a reputable chassis dyno tuner.Why leave power on the table (you will be after the cam) and have an engine not perform up to it's true potential??
You may want to rethink the no resonator.Drive it and see if you have the annoying resonance at any cruise rpm's.
Make sure you replace the valve springs when you do the cam.
Get your mods done(all of them) and find a reputable chassis dyno tuner.Why leave power on the table (you will be after the cam) and have an engine not perform up to it's true potential??
Thread Starter
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Joined: Mar 2011
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I would'nt waste the money on shorty headers.Save that cash for some long tube headers and bullet cats down the road.
You may want to rethink the no resonator.Drive it and see if you have the annoying resonance at any cruise rpm's.
Make sure you replace the valve springs when you do the cam.
Get your mods done(all of them) and find a reputable chassis dyno tuner.Why leave power on the table (you will be after the cam) and have an engine not perform up to it's true potential??
You may want to rethink the no resonator.Drive it and see if you have the annoying resonance at any cruise rpm's.
Make sure you replace the valve springs when you do the cam.
Get your mods done(all of them) and find a reputable chassis dyno tuner.Why leave power on the table (you will be after the cam) and have an engine not perform up to it's true potential??
If the absence of the resonator is too loud, I'll just add it back in. Hopefully that's not the case. It appears to be very restrictive. Loud I can handle, it's that low audible drone at 1600 RPMs that is driving me nuts.
Do you know if the pulley from the LT1 fits the LT4?
Drifting
Joined: Oct 2005
Posts: 1,913
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From: Angier nc
I don't know on the pulley.I would call the manufacturer and hope they know of any difference.I seem to remember the hub being different on the lt4.
The stock resonator is likely restrictive.Magnaflow makes one and I'm sure others do as well that will fit in the tunnel.
I have long tube headers and a corsa catback with the resonator removed.It will be going back in with some hi flow cats.IT is fun when you want to take an aggressive short drive.It is also a pain in the rear on anything else.
The stock resonator is likely restrictive.Magnaflow makes one and I'm sure others do as well that will fit in the tunnel.
I have long tube headers and a corsa catback with the resonator removed.It will be going back in with some hi flow cats.IT is fun when you want to take an aggressive short drive.It is also a pain in the rear on anything else.
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Instructor
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Okay, all of my expectations have been exceeded with this catback system. Generally, I say catback's help very little, if at all, in performance gains. However, removing the resonator seems to have opened this thing up immensley. The car was strugglings slightly from 5500 to 6500 rpm's at wot in 3rd gear. That problem has been solved, as it's wrapping very quickly now. Also, it's actually quieter than before. I can actually have a conversation at 60 mph now.
Now to get started on the optispark and elec water pump.
Now to get started on the optispark and elec water pump.
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Okay, progress report:
I decided (with help from some others here) that I should go ahead and do the cam, heads and intake at the same time. So in the interim I went ahead and upgraded to the Bosch 3 injectors.
Completed items are now: Catback exhaust (resonator deleted) and injectors changed.
So here is my dilemna (hate to keep bothering everyone with this, but I'm indecisive and need some help). Next week, I am going to begin tearing into her. I have my elec WP, new optispark and my cam all ready to go. I have a moroso crankshaft pulley as well, but I'm wondering if I should install it. I'm still not sure if it will have an adverse effect on the elec wp.
again, sorry for the bother. I just don't want to do a bunch of work and have to redo something.
I decided (with help from some others here) that I should go ahead and do the cam, heads and intake at the same time. So in the interim I went ahead and upgraded to the Bosch 3 injectors.
Completed items are now: Catback exhaust (resonator deleted) and injectors changed.
So here is my dilemna (hate to keep bothering everyone with this, but I'm indecisive and need some help). Next week, I am going to begin tearing into her. I have my elec WP, new optispark and my cam all ready to go. I have a moroso crankshaft pulley as well, but I'm wondering if I should install it. I'm still not sure if it will have an adverse effect on the elec wp.
again, sorry for the bother. I just don't want to do a bunch of work and have to redo something.
Last edited by JohnTVette; Jun 9, 2011 at 08:45 PM.
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Okay thanks! I plan on using a 160 thermostat. My worries revolve around the lower voltage coming from the alternator, for the electric waterpump. Am I just being paranoid or is there something to this?
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More than anything, I just didn't want to do all of the work if someone had already been down this route and could give me some insight. My main concern is what effect will it have on the electric waterpump.
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