1995 Impala SS LT4

**donmateo** · 02-04-2012, 01:37 PM

Alright, so I was browsing around at found an ad for a 1995 Impala SS with an LT4. The ad says the guy bought it new, right when it got to the dealer got the $8500 LT4 swap done. The car is an automatic tranny, IK the Vettes with the LT4 came with only Manual. Just wondering if it's legit and how much better it is? Thanks!

Muad'Dib15 · 02-04-2012, 02:47 PM

Not much. They make more power than my LT1 (stock, my LT1 nas a bit more than 260 horses) and have 4 bolt mains, but that's about it. They are down on torque which gets them moving so you won't get going as fast.

just get this: 1996 Impala SS

or this: **1995 Chevy Impala SS**

**donmateo** · 02-04-2012, 03:42 PM

Here's some pics, not sure why they didn't show the first time...

**Dwayne J** · 02-04-2012, 03:52 PM

LT4 was not released till 96 so there is a little quirk in his story.

B-body motor was rated at 260hp @ 5000rpm 330tq @ 2400rpm
LT4 was rated 330hp at 5800rpm 340tq at 4500rpm

Keep in mind the b-body had grandpa quiet intake TRACT and exhaust and 87 octane tuning, once you do full boltons to a b-body and a Vette or f-body LT1 they make the same peak power but the Vette and f-body still don't make the lowend torque the b-body does. My opinion is that the Vette and f-body cams were compromised to limit lowend to save warranty claims on the fragile 7.5" axle in the f-body. So while on the surface it appears the LT4 was worth 70hp and 10tq over the b-body LT1 that really is not so much the case the difference is a lot less than that and the LT4 makes barely any more peak torque but does so 2100rpms later not right for a b-body. His probably didn't make that power either if he expected the dealer to tune it as they do not have a way to put LT4 engine tuning in a b-body program.

Back in 96 this would have been considered cool, BUT these days the ONLY thing the LT4 package has going for it is being all GM stuff IF you could find a LT4 intake. The only other reason for someone to do this now would be raging stupidity, because in fully ported form the LT1 heads work better than fully ported LT4 heads. Benchracers will disagree but I can support the statement.

The 4-bolt main block is the same casting as the LT1 with more holes drilled for the bolts, have to pull the pan to tell them apart.
The LT4 got roller rockers stock, goofy 10mm studs and the rockers are lift limited to well below what is common lift today.
The intake manifold has the same internal dimensions as a late LT1 intake making it the SMALL port earlier LT1 intakes had larger ports, the difference in the LT4 intake is it is powdercoated red and has material above the port to seal to the heads which have a much taller port, beancounters did not let the engineers make the manifold right I am sure they wanted to make the ports larger on it as well.
The LT4 was 10.8:1 compression, the b-body 10.0 and the F-body and Vette LT1 was 10.4.
The LT4 pistons have a little less valve notch for more compression and the rods are fractured cap which makes them stay aligned a little better but complicates a rebuild.

I am sure this is more technical than you wanted but you know me I like to understand things.

There was a time when a lot of people were putting LT4 parts in b-bodies. If you want something not quite stock but all GM then this is interesting, from a perfoemance standpoint though the first thing I would do would be sell the LT4 crap to someone who "believes" and put some good parts on it.

The only LT4 part I would like would be the valves, the intakes were very lite weight hollow and the exhaust were sodium filled, then again with todays cams it is nice to just use a longer aftermarket valve and make room for more spring.
The 4-bolt blocks are of questionable value since by the time you really need 4-bolt you need to be having the block machined for aftermarket caps anyway.

**TSS** · 02-04-2012, 06:07 PM

I have seen this before and it all stuck me as odd too. An LT4 replacement of a perfectly good new LT1, when the car was brand spackin' new?

Dwayne's answer is obviously more complete. I am not knowledgable on the technical stuff like he is, I was just focusing on the "why would you do that?". LOL

**donmateo** · 02-04-2012, 06:29 PM

Well, I saw it and thought $8500 upgrade on a new SS for like no gain except some more lowend torque? Weird....If it's the same price as a used LT1 now is it worth getting? Indifferent? Or don't get it? Not necessarily in the market, just wondering.

**TSS** · 02-04-2012, 07:35 PM

Would be interesting to run the VIN if I had the time.

**donmateo** · 02-04-2012, 07:39 PM

It will come up with a P and normal, since the engine was done at the dealer. Car has 86k miles, from LA, right now it has 26" Asanti rims on it, but only 100 miles on the wheels, sticker still on the tires, so it'd be worth saving. He's asking $9995 with the rims, contact for w/out them. They are $5k rims w/out tires, so IDK what he'd want. I sent an email just out of curiousity.

**Dwayne J** · 02-05-2012, 05:11 AM

LT4 made LESS lowend which must compliment the wheel package really well.

If the same price as an LT1 it would be worth buying and flipping the LT4 parts. Benchracers will pay a premium for that stuff. Would go a long ways towards paying for actual good parts.

**donmateo** · 02-05-2012, 08:53 AM

^Damn, sorry maybe I should be paying closer attention to my reading and writing next time.

Muad'Dib15 · 02-06-2012, 08:30 PM

Wait, unless I'm reading that wrong the LT4 actually has 10 more torques, but it peaks about 2000 rpm higher. So what you're saying Dwayne is that it makes less torque at the same rpm as an LT1 in our cars? That's why it takes off slower than an LT1 powered car. That makes more sense. So if you could get the torque peak down to the same rpm as the LT1, then it would be a decent investment but with that same money you could get an LT1 to be faster.

**C.E.Divine** · 02-06-2012, 08:41 PM

Quote:

Originally Posted by Muad'Dib15

Wait, unless I'm reading that wrong the LT4 actually has 10 more torques, but it peaks about 2000 rpm higher. So what you're saying Dwayne is that it makes less torque at the same rpm as an LT1 in our cars? That's why it takes off slower than an LT1 powered car. That makes more sense. So if you could get the torque peak down to the same rpm as the LT1, then it would be a decent investment but with that same money you could get an LT1 to be faster.

You've got it. Power doesn't do you any good unless it is usable. I would rather have 10% less power over a broader rpm range than have 10% more power in a very narrow band. Im talking something like 330 torques that I get 300 of that torque between 2000 and 4000 rpm vs 360 torques that I get 330 of that between 4000 and 4500 rpm. On other words, I would prefer a torque curve that looks like a plateau, not very high but flat for a great distance, over a torque curve that looks like a mountain, taller than a plateau but very steep, and a quick drop-off.

**Dwayne J** · 02-07-2012, 07:49 AM

You are still missing that the LT4 is 91 octane tuned where the b-body LT1 is 87 octane tuned. That 10tq difference could be made up very easily and cheaply and come in sooner and over a much broader rpm range.

The factory airfilter box on a b-body flows a whopping 450cfm, putting a piece of PVC in place of the rectangular baffle that connects to the MAF is worth 6hp.

Like I said if someone wants something "100% GM" then the LT4 stuff is interesting, otherwise it is pretty much a joke.

Muad'Dib15 · 02-07-2012, 08:19 PM

My cuda's edelbrock flows abot 650. What's so special about 450?

**Dwayne J** · 02-07-2012, 08:53 PM

I was making a point about how choked up the b-body intake tract is.

With port injection we don't need a little vacuum at WOT. With a carbed setup even a performance street setup "needs" to see about 1.5" of vacuum.

02-04-2012, 01:37 PM	#1 (permalink)
donmateo Resident Post-Whore Join Date: Aug 2009 Location: Racine, WI Posts: 10,635 View My Garage donmateo	1995 Impala SS LT4 Alright, so I was browsing around at found an ad for a 1995 Impala SS with an LT4. The ad says the guy bought it new, right when it got to the dealer got the $8500 LT4 swap done. The car is an automatic tranny, IK the Vettes with the LT4 came with only Manual. Just wondering if it's legit and how much better it is? Thanks! __________________ Need to shop? Do it in One Stop! www.basilonestopshop.weebly.com

02-04-2012, 03:42 PM	#3 (permalink)
donmateo Resident Post-Whore Join Date: Aug 2009 Location: Racine, WI Posts: 10,635 View My Garage donmateo	Here's some pics, not sure why they didn't show the first time... Attached Images __________________ Need to shop? Do it in One Stop! www.basilonestopshop.weebly.com

02-04-2012, 03:52 PM	#4 (permalink)
Dwayne J Super Moderator Join Date: Jan 2009 Posts: 1,897	LT4 was not released till 96 so there is a little quirk in his story. B-body motor was rated at 260hp @ 5000rpm 330tq @ 2400rpm LT4 was rated 330hp at 5800rpm 340tq at 4500rpm Keep in mind the b-body had grandpa quiet intake TRACT and exhaust and 87 octane tuning, once you do full boltons to a b-body and a Vette or f-body LT1 they make the same peak power but the Vette and f-body still don't make the lowend torque the b-body does. My opinion is that the Vette and f-body cams were compromised to limit lowend to save warranty claims on the fragile 7.5" axle in the f-body. So while on the surface it appears the LT4 was worth 70hp and 10tq over the b-body LT1 that really is not so much the case the difference is a lot less than that and the LT4 makes barely any more peak torque but does so 2100rpms later not right for a b-body. His probably didn't make that power either if he expected the dealer to tune it as they do not have a way to put LT4 engine tuning in a b-body program. Back in 96 this would have been considered cool, BUT these days the ONLY thing the LT4 package has going for it is being all GM stuff IF you could find a LT4 intake. The only other reason for someone to do this now would be raging stupidity, because in fully ported form the LT1 heads work better than fully ported LT4 heads. Benchracers will disagree but I can support the statement. The 4-bolt main block is the same casting as the LT1 with more holes drilled for the bolts, have to pull the pan to tell them apart. The LT4 got roller rockers stock, goofy 10mm studs and the rockers are lift limited to well below what is common lift today. The intake manifold has the same internal dimensions as a late LT1 intake making it the SMALL port earlier LT1 intakes had larger ports, the difference in the LT4 intake is it is powdercoated red and has material above the port to seal to the heads which have a much taller port, beancounters did not let the engineers make the manifold right I am sure they wanted to make the ports larger on it as well. The LT4 was 10.8:1 compression, the b-body 10.0 and the F-body and Vette LT1 was 10.4. The LT4 pistons have a little less valve notch for more compression and the rods are fractured cap which makes them stay aligned a little better but complicates a rebuild. I am sure this is more technical than you wanted but you know me I like to understand things. There was a time when a lot of people were putting LT4 parts in b-bodies. If you want something not quite stock but all GM then this is interesting, from a perfoemance standpoint though the first thing I would do would be sell the LT4 crap to someone who "believes" and put some good parts on it. The only LT4 part I would like would be the valves, the intakes were very lite weight hollow and the exhaust were sodium filled, then again with todays cams it is nice to just use a longer aftermarket valve and make room for more spring. The 4-bolt blocks are of questionable value since by the time you really need 4-bolt you need to be having the block machined for aftermarket caps anyway. __________________ Dwayne 96 Caprice with AI 200cc package Best et 11.5 Best MPH 116 Just another taxi

02-04-2012, 06:07 PM	#5 (permalink)
TSS Super Moderator Join Date: Mar 2010 Location: Michigan Posts: 5,438	I have seen this before and it all stuck me as odd too. An LT4 replacement of a perfectly good new LT1, when the car was brand spackin' new? Dwayne's answer is obviously more complete. I am not knowledgable on the technical stuff like he is, I was just focusing on the "why would you do that?". LOL __________________ 09 Impala SS (sold 3/2012); 2001 Cadillac SLS ; 2010 Lincoln MKS AWD Ecoboost "Trying Times Are Not a Good Time To Quit Trying"

02-04-2012, 06:29 PM	#6 (permalink)
donmateo Resident Post-Whore Join Date: Aug 2009 Location: Racine, WI Posts: 10,635 View My Garage donmateo	Well, I saw it and thought $8500 upgrade on a new SS for like no gain except some more lowend torque? Weird....If it's the same price as a used LT1 now is it worth getting? Indifferent? Or don't get it? Not necessarily in the market, just wondering. __________________ Need to shop? Do it in One Stop! www.basilonestopshop.weebly.com

02-04-2012, 07:35 PM	#7 (permalink)
TSS Super Moderator Join Date: Mar 2010 Location: Michigan Posts: 5,438	Would be interesting to run the VIN if I had the time. __________________ 09 Impala SS (sold 3/2012); 2001 Cadillac SLS ; 2010 Lincoln MKS AWD Ecoboost "Trying Times Are Not a Good Time To Quit Trying"

02-04-2012, 07:39 PM	#8 (permalink)
donmateo Resident Post-Whore Join Date: Aug 2009 Location: Racine, WI Posts: 10,635 View My Garage donmateo	It will come up with a P and normal, since the engine was done at the dealer. Car has 86k miles, from LA, right now it has 26" Asanti rims on it, but only 100 miles on the wheels, sticker still on the tires, so it'd be worth saving. He's asking $9995 with the rims, contact for w/out them. They are $5k rims w/out tires, so IDK what he'd want. I sent an email just out of curiousity. __________________ Need to shop? Do it in One Stop! www.basilonestopshop.weebly.com

02-05-2012, 05:11 AM	#9 (permalink)
Dwayne J Super Moderator Join Date: Jan 2009 Posts: 1,897	LT4 made LESS lowend which must compliment the wheel package really well. If the same price as an LT1 it would be worth buying and flipping the LT4 parts. Benchracers will pay a premium for that stuff. Would go a long ways towards paying for actual good parts. __________________ Dwayne 96 Caprice with AI 200cc package Best et 11.5 Best MPH 116 Just another taxi Last edited by Dwayne J; 02-05-2012 at 05:22 AM..

02-05-2012, 08:53 AM	#10 (permalink)
donmateo Resident Post-Whore Join Date: Aug 2009 Location: Racine, WI Posts: 10,635 View My Garage donmateo	^Damn, sorry maybe I should be paying closer attention to my reading and writing next time. __________________ Need to shop? Do it in One Stop! www.basilonestopshop.weebly.com

02-07-2012, 07:49 AM	#13 (permalink)
Dwayne J Super Moderator Join Date: Jan 2009 Posts: 1,897	You are still missing that the LT4 is 91 octane tuned where the b-body LT1 is 87 octane tuned. That 10tq difference could be made up very easily and cheaply and come in sooner and over a much broader rpm range. The factory airfilter box on a b-body flows a whopping 450cfm, putting a piece of PVC in place of the rectangular baffle that connects to the MAF is worth 6hp. Like I said if someone wants something "100% GM" then the LT4 stuff is interesting, otherwise it is pretty much a joke. __________________ Dwayne 96 Caprice with AI 200cc package Best et 11.5 Best MPH 116 Just another taxi

02-07-2012, 08:53 PM	#15 (permalink)
Dwayne J Super Moderator Join Date: Jan 2009 Posts: 1,897	I was making a point about how choked up the b-body intake tract is. With port injection we don't need a little vacuum at WOT. With a carbed setup even a performance street setup "needs" to see about 1.5" of vacuum. __________________ Dwayne 96 Caprice with AI 200cc package Best et 11.5 Best MPH 116 Just another taxi Last edited by Dwayne J; 02-07-2012 at 09:09 PM..

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