Whizbang

got it for a amazing price. i just need a wiring harness and transmission. but im stuck on that decision. What transmission should i look for? i prefer manual shift, but an auto tranny would be easier to come across. So it comes down to two things, how does each act on freeway driving and which has a better acceleration?

Also, just curious if anyone knows, if i use the Grannys basic (poor college student and dont want to make a cradle) would the oil pan from the police vechile need to be modified? i have a feeling it will. but i dont have the 7 to but it into yet to check (getting all the conversion parts first).

jimlab

Just FYI, there was no difference between the LT1 in the Caprice and Police Intercepter except for the green silicone coolant hoses.

A manual transmission doesn't sap as much power as the automatic and is considerably lighter, but the automatic has torque multiplication thanks to the torque converter. It's probably a toss-up, with the edge maybe going to the automatic because you don't lose time to shifting.

As far as freeway driving, the final drive ratio in the overdrive gear(s) will determine how many rpm the engine will be turning at a given vehicle speed. You need to specify which transmissions you're considering, since they don't all have the same gear ratios.

stilettoman

iTrader: (1)

I used an old style mechanically controlled AOD tranny with my 302, which has an overdrive ratio of .667 (2/3). With 225/50-15 rear tires, I am turning 2400 rpm IN OVERDRIVE at 60 mph. That is a bit fast for a V8 in such a light car - mine weighs 2550 without fuel. For acceleration at freeway speeds, I can outrun most cars without shifting out of overdrive! I am only putting down about 250 HP, so this is just a daily driver. It is all about torque.

If you go with an automatic, I highly recommend one of the later style trannies. You will get a lot of grey hair trying to sort out an AOD, unless you just get lucky.

88IntegraLS

A voice in my head is telling me to tell you that it's not about torque, it's about available power in any given situation.

Because your engine has so much available power at highway speeds because it has so much torque at that rpm, you can walk most cars, which are not in their power bands when cruising the highway (probably for gas mileage reasons).

[/the voice]

stilettoman

iTrader: (1)

What the voice is telling you is correct, but you miss my point. The reason my V8 has so much torque at that rpm is that it has a lot of torque at EVERY rpm. Compared to a normally aspirated rotary, I have maybe 3 times the torque average over the whole rpm range. If the rotary is boosted and getting 400 rwhp, then I only have twice as much torque, and of course about ten or twenty times the engine life!

Some of the guys with the V8 conversions are pumped up to 400-500 hp, but I don't see that as being very useful on the street. For me it isn't the thrill of outrunning somebody - it is the symphony of car alarms I set off when I drive into a parking garage! People rarely want to mess with me at stoplights unless they have their stereo cranked up and can't hear my exhaust.

The most fun was the reaction I got the first time I drove it into the shop at the local Mazda dealer. All work stopped and the mechanics gathered around waiting for me to open the hood. "Hey this thing doesn't idle very good. Can you guys help me?"

Whizbang

so...a 700R4 or a TH400 then?

88IntegraLS

Lol. I might try to keep mine somewhat quiet, for the element of surprise.

Whizbang

okay someone told me that a 4L60E is the choice for the automatic. So, i guess that is the route to take. Or if i find a T5 at the yard then i might just use that.

digitalsolo

iTrader: (2)

A T5 isn't likely to last long between even a mild LT1. They can be built to take some punishment however at that point in investment a T56 would be a much better option, and were a factory option in the LT1 F-Bodies; the T-56 can be built to handle nearly anything you can throw at it (within reason), the Viper and Mustang Cobra utilize it as well.

jimlab

I'd recommend a T56 too.

digitalsolo

iTrader: (2)

The LT1 uses a different style TO bearing then the later units, correct?

Whizbang

looks like it might come down to what i can find locally at the various yards. if i can get a T-56, im on it, but in reality, whoe knows, just need to search.