Murc

I wanted to know how much weight the LT1 gained when it became an LT5 on the ZR-1 with DOHC and added chains, valves, springs and larger heads. (correct me if I named the engines wrong)

AAron

they arent at all the same. the LT5 was designed by a marine engine company, i forget who off the top of my head. they had no major interchangeable parts.

but it was aluminum and did gain that much weight. from what i remeber. dont have all my books here that listed the specs.

Murc

Well, what I was wondering was the engine in the ZR-1 a) based of the stock corvette engine b) if it was, what all was added and was it any more than the part in the valvetrain, and how much weight it added. A friend of mine is trying to say it added around 100 pounds, and I don't think that sounds right.

AAron

yeah like i said it was a totally different engine, not based on the LT1/4. as too the weight 100 lb. isnt too far off.

z28boysteve

iTrader: (9)

that motor was a partnership between mercury marine and some other people, doesnt even resemble a small block chevy

Camaro97USAF

wasn't it mercury marine that did that? I think it was them with help from Lotus or something like that. I'm not really sure off the top of my head. Bad *** motors though. Not anywhere near the same as an LT1 though. It'd be nice if parts interchanged though...


Damn he beat me to it...

OutlawZ

iTrader: (4)

Yeah the LT5 was an engine designed by Lotus.... No interchangeable parts with an LT1 or LT4 family of engines.... Basically a dual overhead cam smallblock chevy that made somewhere in the area of 405hp...... I'd like to ask all the people that still own ZR1's how expensive it must be to find parts for that thing nowadays......

tooquick2beslo

Yea, It was made by Lotus and the company almost went bankrupt making that engine.

transamman400

iTrader: (1)

LT5 summed up...

1985, GM asks Lotus to make a DOHC version of SBC. Lotus says the motor isn't compatible, inadequate to handle it and poor cooling properties. Needs to re-engineer a whole block.

1987, creates their own motor from scratch with same 4.40 bore centers as SBC, but with smaller bore and longer stroke, with an end displacement of 348 cubic inches. This is a completely new block.

1988, Mercruiser, builder of GM marine engines is chosen for the contract of building it, as they have tools for specially designed and built motors. From Mercruiser, they will be shipped to Bowling Green for installation in the Corvette.

1991, LT5 receives a bump in horsepower from machined inlet runners, blending the valve heads, and other minor work. Horsepower becomes 405.



A little known fact about the ZR1 is that further development of the program was already canceled by fall 1991 realizing they could make that kind of power with pushrods. Lotus advised Chevy that making simple revisions to the motor could yield 450-475 horsepower but they declined. The LT5 was already built out by 1993.

96capricemgr

iTrader: (1)

So what they are saying is the LT5 was BEFORE the LT1 and not worth a damn anyway. An LT1 can make substantially more power for less money. The ONLY purpose an LT5 could have would be bling, but those of us knowledgable enough to know it was not worthwhile would not be impressed. Tim Allen paid GM a reported 6 figures to put one of these things into his b-body Impala SS several years ago, it required some firewall relocation as the story goes anyway.

AAron

it is like a cobra motor. done right it could spank a LT1/4 but that is every motor.

being an ME major i personally love the thought of a DOHC small block. they just need more R&D to make a better one. but for its day it was an engineering masterpeice.