ramey

Trying to decide the best course of action for aluminum high horsepower engine in 87 4+3 streetcar retaining AC and preferably but not necessarily emissions compatability. I really want your input regarding option 2, the LSx swap.

Option 1 brodix block & 23 degree heads, 447 cid, 315 cfm flow in heads is about my limit. Intake is a pain, I understand a victor jr with a Force style throttle body will have about 2.5 inches of room under hood; this intake will choke things a bit…

Other ways around the intake are cross ram old efi manifold converted efi. Probably bs3 wide band ecu.

Other than that, this is a bolt in deal. Expensive


Option2

LSx motor; problems here are, as I understand it,

Include bolting up the LSx to the motor mounts and trans (once the trans blows up I will go with a Keisler 5 speed, bolts in and uses same clutch/flywheel as 4+3 I believe)

Street & perf mounts are .5” too low and apparently 1.25” too far forward.
If you find others (good source?) or make them, you have to cut the firewall because the LSx heads are 1.5 or so inches further back in relation to the bellhousing mating surface.

I understand the LSx clutch uses the same splines as the 4+3 muncie/t-10 fine spline older models… right>?

The bellhousing I understand just bolts right up on the LSx, just missing 1 hole, no big deal…

Or the Lakewood 15005 bellhousing will mate it all up correctly; will that work with the 4+3 and hydraulic clutch?
I understand the gm pilot bearing 12557583 will mate up the trans to the LSx crank also.

I understand that Mac full tube 00-02 F body headers are a bolt in?

I understand the easiest thing is use LSx AC and a high passenger mount from Street & performance?
I understand the PS pump pressures are way off; any suggestions for using the l98 ps pump on the LSx motor?

I understand that the dash will work separate, with oil and coolant having separate senders for the dash? But where do you mount the senders in the LSx?

I understand that the LSx tach signal is halved, so you need a doubler which you can get from LS1 tech ?

I understand you can get a VSS adapter from the old trans to the LSx computer for like $160?

I understand you can get an easy stand alone painless wiring harness, and it really just needs ignition power, VSS, and ground from the car? Does it need any other inputs?

Is any of this info wrong? Have I missed something important? Which oil pan should I use? Will the front crank pulley clear the cross bar on the vette? How much cutting must be done on the firewall? Are there any engine mount adapters that will fit right in the c4?

Are there any other issues with bellhousing/flywheel/block depth/input shaft and pilot bearing issues?

The LSX swap would be a bit cheaper, but more trouble. Overall I think it would be lighter too, and make a tad more power, as you can get good heads flowing 370+ for the LSx motors.

Any thoughts or templates for PS lines, alternator, and AC lines and brackets?

I sure appreciate all of your input.

Also, if there are any weird issues I should know about with the option 1 SBC blocks, the brodix heads, or the Exotic muscle 1 7/8 inch headers I would appreciate hearing your stories and input. Same of course with intakes that fit under the hood.

ramey

ttt please

93Polo

iTrader: (5)

some good ifno in here;
http://forums.corvetteforum.com/show....php?t=1203191

EM was coming out with a 1 7/8" LT with a merge collector for a std. SBC but nobody had them yet on CF

ramey

actually, that whole summary I gave was from searching LS1tech and corvetteforums, including that post. I was hoping someone could fill in the questions remaining from those posts....

Thanks

J-Rod

Ok, there was a user on here who had done 2 swaps of an Ls1 into a C4. I've certainly given it some thought. In fact last night I started thinking about this topic. I tried to think of which year C4 would be the best to swap to. I really thought an 84-85 might be the best. Reason being is the engine controls in the 84-85 are much less in 87 on (85 still has a conventional distributor), and it is a non-ABS car.

But, I sat down and tried to think of how you could integrate a newer GM computer, and still drive enough of the car's original harness/computer. To make it all work. In other words, still get the gauges to work, and even perhaps the check engine light while not having the stock computer get "unhappy".



There was a memeber on here VTESPEED
(Find all posts by him)
https://ls1tech.com/forums/search.ph...nduser&u=24530

Who was a wealth of information on swaps.

ramey

I am curious about a Wilson manifold; question is always with a custom manifold, will it make good power? Manifold design is not exactly simple science; the concepts are easy, but weird resonances or reversions can always unexpectedly pop up, and could make the whole thing a multi thousand dollar waste.

On the LS1, I did learn through other sources that the crank sticks on .400 further on an LS1 than on an SBC, relative to the block face.

I guess I am still having a bit of trouble figuring out exactly how all that will fit together, either with the 4+3, or with a Keisler 5 speed; I have an email into them to see if they have a simple solution.

T56 is rather a pain in the *** to swap in due to the torque arm, so I am not sure that is the most cost effective route either.

I have a car now, J-Rod, 87, real clean. I do want to keep the AC, I understand that S&_ has various brackets to relocate; I will follow up with that research.

J-Rod

Wilson designed the FAST intake. It makes more power than an LS6 this is well proven. They are also coming out with a sheetmetal manifold which I think was at PRI.

I guess it depends on what RPM range you want to be in. Most of the Carb style intakes, sheetmetal intakes, etc... are downa bunch of power under 4500 rpm. But power over 4500 comes on like gangbusters.

Then of course you could go Harrop 8TB which will fill in the area under the curve, and make good power, along with taming down the cam.

93Polo

iTrader: (5)

There is a T56 conversion kit on the market. I do not know much about it other than finding the link on CF. I have not tried the swap but searched and lurked on CF like you.

http://www.prostreetcustoms.net/CorvettePage.html
http://forums.corvetteforum.com/show...56&forum_id=48

ramey

hmmm... t56 conversion may be the easiest way to go; I have an email into them to see whether their conversion will bolt in with the LS style t56.