how to tell LT4
Thread Starter
Joined: Mar 2003
Posts: 8,319
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From: North Carolina
how to tell LT4 how can you tell a motor is an LT4 and not LT1, and if you know how can you tell its an LS6 and not an LS1, this is on an engine swap put in on a Z28 that was stock an LT1
Re: how to tell LT4 the only way you can really tell if its and LT4 is, the intake painted red (assuming nobody got some red paint and painted an LT1 intake) with a 52mm throttle body, and the throttle body plate should say "GRAND SPORT".the intake also has longer intake runners for high end horsepower versus the short ones for torque like on the LT1 intake. it also does not have an EGR. as far as the heads go, if im not mistaken, the heads are 18 degree heads, so they will sit a little more at an agle versus an LT1 head. but dont quote me on that last sentence. as far as the LS1 and LS6 the only way i can tell the two intakes apart is the EGR is not on the LS6 while the LS1 intake does have an EGR. I really dont know too much about the LS1 and LS6 heads other than the "D" shaped exhaust ports on the LS6 head. still doing my homework on the LS1 head versus the LS6 head.
Re: how to tell LT4 The 97 and newer vettes with the ls1 do not have an egr valve either.Lt4s have roller rockers. The part # for the lt4 intake is 12550630. I believe the intake cannot be mounted to lt1 heads.
Teching In
Joined: Nov 2002
Posts: 16
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From: Lafayette, IN
Re: how to tell LT4 The LT4 engines do have the red intake, but they do NOT have 52mm throttle bodies. They are twin 48's like the LT1. (BTW, it won't necessarily say "Grand Sport" on the throttle body....only 1000 Grand Sports were made, and the rest went in Collectors' Edition Corvettes, as well as 100 in special edition SS Camaros) As for the heads, the intake runners on an LT4 head are raised .1 or so of an inch, thus the intakes and heads will not interchange without port match problems. The letters "LT4" will be cast right into the top of the head and is visible if you remove the valve cover, and they came with 2.00" intake and 1.55" exhaust valves, with the LT1 head they were 1.94" and 1.50". They are also a 4 bolt block, (so is an LT1 if it came from a vette) and will have a single roller timing chain, as opposed to the standard links found in an LT1. 1.6 aluminum roller rockers are in place of the stamped steel rockers. I'm sure there are many more differences, but this is all I could come up with off the top of my head. Hope it helps.
<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
<img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
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Teching In
Joined: Jan 2003
Posts: 15
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From: West Lafayette, IN
Re: how to tell LT4 Time for me to chime in on this one <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
All LT4 motors that went into the 96 Corvettes do have the "Grand Sport" thottle body. The 100 that went on some of the 30th camaro SS's do not however. Also thier were LT4 Corvettes that were not GS's or CE's all 6-speed in 96 were LT4's
A good way to tell if its an LT4 or not other than the intake color is to look and see if it has EGR on the car....on the back of the intake look and see if thier is an aluminum plate blocking the EGR hole. It will still have the tubes going from one manifold to the other but it will not connect to the intake like LT1 cars. Hope this helps <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
<small>[ March 26, 2003, 09:27 PM: Message edited by: MongooseLT4 ]</small>
All LT4 motors that went into the 96 Corvettes do have the "Grand Sport" thottle body. The 100 that went on some of the 30th camaro SS's do not however. Also thier were LT4 Corvettes that were not GS's or CE's all 6-speed in 96 were LT4's
A good way to tell if its an LT4 or not other than the intake color is to look and see if it has EGR on the car....on the back of the intake look and see if thier is an aluminum plate blocking the EGR hole. It will still have the tubes going from one manifold to the other but it will not connect to the intake like LT1 cars. Hope this helps <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
<small>[ March 26, 2003, 09:27 PM: Message edited by: MongooseLT4 ]</small>
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