Hello, I am very new to the LT1 engine, having never worked on one other than putting on some aftermarket intake pipes, and driving a few T/As around from time to time. I am however above-averagely mechanically inclined, I've built a dodge stealth that still retains a stock 3.0L engine that's very very fast. However recently I was bitten by the V8 bug and i've decided to invest in a rather complicated project.

My car is a 1985 RX7. The engine is an LT1 with rod knock out of a 94 Z28 A4. I am building the car to compete on a road course (road racing suspension, wide body, T56 transmission) however I'm hoping that with a spring change, shock adjustment, and a large dose of N2O it will be a 9 second beast.

The car itself will be very light, completely stripped, fiberglass widebody, 12 point chromoly cage, bucket seats and some fans under the dash, that's about it. I would like it to be a barely liveable daily driver, while mostly being a track car, it will be registered and insured as a street car. I'm going to put a Ford () 8.8 in the rear end and build it, however it will have a good LSD, no locker here.

The motor is going to be a 383ci LT1. I've got an Eagle forged crank, H-beam rods and SRP pistons. The block is going to have splayed mains put in. It will be getting a 200 shot at the strip, and maybe occasionally on the street. I've found some very nice NX and NOS setups, it will not be a playschool setup either, this thing will have all the safety equipment available. For the ignition on it I'm trying to find information on converting to the DIS-4 from the Northstar, as I'm sure I'll be requiring powerful spark on the high end for extended periods of time. My questions ultimately come down to my head and cam options.

My goal for the motor is about 500-550 crank horsepower N/A on pump gas. I've got some friends with the desktop dynos and they're saying that Crower's largest nitrous cam is too small for the power I'm looking for. Does anyone have any suggestions? I would like idle to not be over 1700RPM, and redline to be under 7000RPM, because I want streetability to exist (somewhat ) I'm hoping for something that doesn't have much over 245/260 duration, and over .550" lift.

In addition to this I'm somewhat hungup on the heads question. I've been looking around and it seems my best options are the AFR 210LT4 or 220 LT4 heads, however on their website they say I'll need an LT4 intake manifold. Is this true, or is this simply for optimal flow. also these heads will be seeing extensive high RPM on the roadcourses. Alternately, does anyone have experience with other company's heads that are competitive, being used in this type of atmosphere?? Ai, LPE, etc...

Thanks for your help, I've been using the search button but as the forum is filled with some on topic some off topic information, I haven't quite learned the best words to use in the searches to make them efficient. Also my apologies if this is the wrong message board for this, I found it crossed into many categories, so I thought I'd post it here, as most LS1 people are former LT1 people

thanks for your time, David

 

the LT4 heads or LT4 style heads such as the AFR's require the LT4 intake. You will need LT4 style heads. I think the AFR 210s will suit your needs fine. The 220s require so many other parts to work such as shaft mounted rockers.

You can stay hydraulic roller, have streetalility, and be within your cam and RPM specs while meeting your goals of 550-550 crank hp. A few people to talk to would be Lloy elliot at www.eportworks.com . Advanced induction and Futral Motorsports are other companies to talk with as well about your combination. Oh and the guys at HPE are good with the LT motors. You may consider solid roller, but the maintainence is a pain with always having to adjust the valve lash.

from what i understand desktop dyno is not accurate so i wouldnt use that.

also try www.camaroz28.com for good LT info

good luck. sounds like a fun project

 

Well the cam specs you are eying out wont do the trick, too small. The extra cubes you are going to have to play with will make the cam more streetable. If you really wanted max power, you could go a 396 stroker. You are definately going to have to have a killer heads/cam setup to get power. Get some AFR's and have someone grind you a custom cam for your needs. Id suggest you go over to www.camaroz28.com since that board is alot more LT1 oriented. You will get all the advice you need. But definately dont go with an off the shelf cam. Talk to Lloyd Elliot, or Bret Bauer and work with your goals in mind.

Should be a cool project, post pictures

 

Hey thanks for the info guys. I was originally planning LS1, but I didn't like the idea of having to re-engineer the K member and an oil pan to work. Besides my friend on here is doing one in his 2nd gen RX7. So I just couldn't follow hiM!