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View Full Version : Motor Options? Blew up the old one


Admiral
03-07-2005, 11:04 AM
OK, I don't want to tip my hand to my GM competitors or fellow blue oval rivals here in TX but I need some input on what to put back into my SN95 for AI. We blew up the old 111K mile motor this weekend. A GM LS1 was kicking my tail around the track, he's got 340HP/360TQ to the rear wheels.

Should I look at a 331 or 306? I need the TQ badly IMHO. At my weight I can have 330HP/350TQ at the rear wheels. I'm just not familiar enough with the options available and the pros/cons of each. Any advice or input is appreciated as I've got to get one built for the next race in May.

johnbasf
03-07-2005, 12:14 PM
Mike, I'm no motor guy but the 331 is pretty popular on the East Coast. I'll say no more. :thumbsup:

Admiral
03-07-2005, 12:50 PM
Interesting. Thanks for the info John. Anyone running the much-maligned 347? Anyone doing the 351 in AI? I know its a bit heavier but I need some TQ badly, lol.

Cobra-R
03-07-2005, 02:24 PM
Mike,
FYI: In my 95 Cobra R with the stock 351, it dyno'd 269 rwhp and 356 rwtq. The engine has never been opened up in any way. Other than some bolt-ons like exhaust, air pump, ect, it's stock. 7400 miles with probly at least 6000 of them being on the track, still as strong as ever.

With a better set of aluminum heads and some tuning a engine like that would give you the numbers, be relativly cheap, and very reliable.

Brian

Admiral
03-07-2005, 02:45 PM
Brian,

Sounds like a TQ monter. What does that car weigh? I'm trying to say close to my current weight and get a stronger motor so I may not use the 351, I've read where it puts as much as 75lbs more on the nose of my already nose-heavy car.

Cobra-R
03-07-2005, 04:27 PM
Brian,

Sounds like a TQ monter. What does that car weigh? I'm trying to say close to my current weight and get a stronger motor so I may not use the 351, I've read where it puts as much as 75lbs more on the nose of my already nose-heavy car.


Last time I corner weighted it,(it has a full MM suspension with coil-overs, full cage, two seats, stock dash) it was at 3653 lbs with me in it and a full fuel cell (I weigh about 180) I'll be corner weightning the car in the next day and will update the numbers.

I only mentioned my setup to be a budget minded combination, probly not the best performaning. The 351 seems to be able to provide the numbers without putting in somewhat exotic(ie: expensive) parts or stroking.

Brian

justagt
03-08-2005, 05:35 PM
Mike,

I have a .030 351 and love it. If you decide to do one, let me know. There are some tricks you can do to help it oil itseld much better.

Admiral
03-09-2005, 08:10 AM
Thanks for the info and offers for help. I'm probably going to stick with the 306 or 331 combo for now, I think we can make the AI ratios without adding weight to the car if we do it right. The spec tire doesn't need any more weight on it with the way I drive, lol.

I'll report back with the results once we get the new mill installed and dyno'd.

Cobra-R
03-09-2005, 10:05 AM
Mike,
My car weighs 3393 lbs full of fuel, no driver. 3576 with me in it. Overweight and underpowered makes ya a better driver. ;) Good luck with your racing and engine.

Brian

BOC- Beau
03-09-2005, 10:50 AM
If you have any intentions of losing weight in the car, I would go with a well built 306. You should be able to get the numbers out of the smaller engine easy enough. The reason that I would steer you away from a 331 is the torque rule. If you build the engine and then later decide to lose weight in the car, you will be fighting with the torque with the stroker. If you are sure you will not change the car, a milder 331 is a good choice.

Admiral
03-09-2005, 11:35 AM
Beau,

Good point but I'm not much of a race-car mechanic so I wanted to build a mild stroker and quit worrying about where I can lose the last 360lbs. I'm at 3160 right now post-race with driver. All the easy weight reduction stuff is done ;)

After seeing an LS1 lift the inside front tire on corner-exit when in front of me or behind me I think I'm behind in the TQ department. I was leaving alot on the table with my old mill, dyno'd at 298 RWHP and 317 RWTQ, I'd like to get much closer to the allowed 332HP/351TQ numbers (for my present weight) and just drive the darn thing for a few years, I need the experience and seat time!

While I'm asking, what is the general consensus on solid motor mounts and tranny mount? I'm sure the stockers will need to be replaced while I've got the motor out! Thanks again for your opinions/input/advice!

etm63
03-09-2005, 02:27 PM
I use the urethane mounts (engine and tranny) and have been very happy with them - no problems (and I still have the fillings in my teeth...:D )... They are kinda the "middle of the road" and I like 'em...

On the motor, while I'm no expert and as much as you don't won't to hear it - I'd worry more about how to lose those 360lbs and go with a milder engine setup (like Beau mentioned). As you know, the weight loss is benefitted by all...

Personally (I'm also getting ready to change motors), I'm gonna try a crate motor - NA 302. I'm VERY concerned about durability and thats my main focus - I'm hoping I can make up whatever disadvantages I'll have with track time (experience), improved suspension tuning, being able to fininsh races, etc... Oh yeah, and LOSING WEIGHT!!!!:rotf:

Good Luck,
Ed