What motor
 

I am still in the planning stages with my 94 rx7 and I need help in which direction to go with the purchase of a motor (I currently do not have one).

The car will be a street car with as much power as I can afford. When I say street, I want to be able to pull up to a gas station (93/94 octane) and fill up. I don't want to use NOS or any turbo/superchargers. I want a displacement of 7 liters (427). The routes I am thinking of going is:

1. Purchase of a used LS2/T56 and have it sleeved to 427 and then add heads and an intake system.

2. Purchase of a crate LS7 and buy the accessories and T56. Eventually down the line add mods as they become available.

3. Purchase the LS2/T56 sell the block and heads, keep the accessories, purchase a short bock LS7 (when it becomes available), buy etp heads, and an intake system (fast/harrop).

I understand the cost and availabilty of a LS7. I am not doing this as a budget project over cost of a rotary. I like the idea of having more power/torque, a reliable (at least more reliable than a rotary at that power level) and mpg. I have a budget of around 14-16k for motor alone.

I believe, as of right now, that the second option is the best option for me. I can still purchase a harrop intake system, that coupled with custom headers and exhaust should put me at a decent power level. I currently have a new standalone, but I have to find out if it will work with a LSx (it was for my 92 VW Corrado 3.0T). And I know the oiling system still has tobe figured out. My assumption is with the downtime between purchasing this motor and transmission, waiting on other parts and the sale of my corrado (this is extra money for just in case) the few things that have to be figured out would be by then.

If it matters the rx7 has been payed off, the rotary (last I checked 3 years ago) still works and I have all those parts to sell, I have no outstanding debts and I still live at home with mom and don't plan on moving out for another 2 years, ha ha. So I have the money to play with and the space. I don't see this as an overnight project and would rather not be. For all I care it can take me 2 years to complete.

What do you think is the best option for me? Is there another option I have not listed?

Thanks in advance and thank you to those I PM'd for advice

I say do the LS7. Great engine out of the box.

14-16K in the motor.... heh. Big cubes, big heads, forged balanced blueprinted everything, and you should prolly look into building up the T-56 a lil too while youre at it to handle the power and shift better.

You might also want to look at getting a cobra rear for gearing and strength.

And, well, obviously, many people would say put the money into a damn house and dont blow so much on a car at this part of your life.

LS7 will be heavier I believe. Use the LS1 and build. I read a complete article where with the build they were putting over 500 at the wheels.

Do the T-56 from the viper to ensure the trans can handle the power.

Change the rearend and related parts to handle the power.

I put an LS6 with upgrades in my Street RX7. However looking back for the money you want or can spend, you might want to try the LS1 with the proper build to acheive the power you want, need, have to have, can't live without.

Good luck.

Allan

Heavier? Why do you think that? Bigger displacement doesnt mean its physically larger on the outside. (The ls7 is TALLER because of raised runners on the heads, but thats completely different) Its a LS2 block with a bigger bore and a 4" stroke. Its not going to weigh more. The Dry sump oil system might add weight by having more oil but other than that.... uh, no.

Ive seen 500 @ wheels from a 402 cid (6.6 liter) LSx motor with a mild cam. LS7 is majorly corked from the factory - 600 or more is nothing.

Weight of the new hand-built LS7 (160 views)
Message: The following is from the January 2006 issue of Sports Car International on page 25:

"The net result is a fully trimmed engine that weighs 458 pounds, only 10 more than the 6.0-liter LS2."

For comparison, AMG's all-new 6.3 liter V-8 (it is actually a 6.2 liter V-8, but it will be called a 6.3 liter V-8 to pay homage to the 250 hp 1967-1972 300SEL 6.3) weighs 438 pounds vs. 485 pounds (old 5.4 liter supercharged V-8). The new V-8 has 510 hp at 6,800 rpm and 630 Nm at 5200 rpm.

Also, BMW's M5 Product Information Guide says that the M5's 5.0 liter 500 hp (SAE net) V-10 weighs 240 kg/529 lbs.

Yes Hevier
 

Unless I am mistaken ONLY 10 MORE LBS DOES MEAN HEAVIER!

Weight of the new hand-built LS7 (160 views)
Message: The following is from the January 2006 issue of Sports Car International on page 25:

"The net result is a fully trimmed engine that weighs 458 pounds, only 10 more than the 6.0-liter LS2."