I'm sure this topic has been covered in some comments somewhere, but I'd love to hear from people with some experience.

Before I go into my specific details, my main question is: if all I ever do is use it as a DD and occasionally some mild street pulls on stock width tires, how much horsepower is necessary? Will the average driver get any benefit going from 350 to 450 hp? For any drivers with DD experience who have went over the 350hp mark, was it worth the time/money?

Me Specifically

To start with, I'm in the process of purchasing crashher0's sedan. If you're not familiar with it, here's his background story/build:

https://www.cobaltss.net/forums/08-1...thread-308136/

In summary, he started to build the car with a goal of 500hp. When he ran into trouble getting an f40 set up with the car, he never finished it. That being said, it's a Gen 3, fully set up with an s256et stage 3 kit, fully bolted, tuned, etc.

In my opinion (though I've never built one over 350 hp myself), with pistons/rods, 5th injector, and cam, it should be capable of 450+. However, I'm still on stock tranny. Is there any benefit to me aiming for that higher hp? He has such a nice start, but I will 500 hp be a total waste in my car? It's currently tuned to around 350 hp @ 23 psi until it gets completed. Should I just be content?

Just looking for opinions and experience from DDs

 

I used to be dgmanrocks on here, and owned an 09 sedan back in 2011. Somehow I can't get my old account to work, so I'm now dgascho with 2 posts lol

 

I'm at 481hp but swapped to a 4.05 LSJ trans i ran it for a year with no trans issues. What i recommend is find a good middle ground between spool and max power. I think running a 256 at only 350hp is a waste but also the spool is way smoother than the k04 so it wont shock the trans with torque the same so on a good tune even in the 400hp range it'll be safer

 

If I'm understanding you correctly, you think a 256 at 400+ wouldn't necessarily destroy a stock tranny (at least not right away) because of a smoother spool? Zzp seems to think the ldk rods/pistons won't handle over 350hp. I'm assuming some have failed along the way?

 

With a good tune you'll be fine. Im 100% stock gen 2 engine so you'd think the gen 3 can do at least that

 

I'm running the s256 stage 3 kit from zzp in an auto hhr ss 08 gen 2 tuned to 405 with boost limited in 1st to 12lbs. I've had no issues since april. Not a daily driver, I would be in trouble if it was. Too much fun!

 

In the spring I'll be going to the dyno again with a couple more mods still stock block until my build is done. I'll try to get a tq reading next time people have been asking about it and all i saw was minimum 402

 

I know someone trying to sell a good set of 4.45 gears. Would really help your tranny to live. I just purchased a rebuilt 4.45 trans from him. Think he wants $500.

 

I'm gonna stick with the 4.05 for a bit I'll have a couple spares for next year. I wanna go with the f40 but if i have no other option after my build I'll do the 4.45s

 

I'm assuming you're still on stock internals? If so, you guys are giving me hope! Who are you tuned by, if I may ask?

 

Yes my dyno was on 100% stock engine I tuned my car

 

Thanks for help. Should've clarified, Mississippi are you stock?

 

Quick question what are the main benefits of the 4.45's? I always feel like my gearing is too short, and would like a bit longer gears. Especially first gear..
f23, but potentially want to get zzp 2.4 clutch kit to do a SS turbo f35 swap. Because lnf and lsj f35's have different final's right? (not trying to thread jack)


Thanks

 

Then you would be going the wrong way with 4.45 gears. Stock lnf is 3.82, lsj 4.05, 4.45 comes from Saturn trans I believe. 1st gear is super short in a 4.45 trans. The 4.45 gears take some load off the trans to help it live. Plus they can improve acceleration.
Many rwd cars go from say 3.23 gears to 3.73 gears to help 1/4 mile times. Same principle on our fwd cars.

 

I wasn't so much curious about the acceleration aspect of the final gearing. Earlier you mentioned 4.45's would "help the transmission to live". The acceleration part is something I am more familiar with.
But if shorter gearing is easier on the transmission, and will increase longevity. That's a good thing to know, and would make for a good reason to shorten up the gears. I suppose it would make sense that shorter gears builds less torque on the shafts? because it allows the engine to rev more freely?

 

Think of it as a small gear moving a lever. The 3.82 is a small lever so it puts more stress on the gear vs the larger 4.45 gear which puts less stress on the gear. I've also noticed that the 7163 comes into boost smoother than the torque spikey k04. I'm interested how much i can get my LSJ 4.05 trans to hold next year.

 

That's more what I was looking for.


Looking forward to your build you have coming up.

 

Thanks! I'll be doing it in 2 stages finishing my topend build and hopefully finishing the full engine by early summer

 

So you intens to do the top end and then the bottom end?

 

Me or OP?

 

Just to get to the orginal topic...If I remember reading correctly, ZZP found the rods in the LDK to be a weak point and were breaking around 400whp.

360whp+ is plenty for my daily summer driver. I had a bigger turbo and ended up selling it after getting my E tune dialed in. Plenty of fun for what it is.

But if I were in your scenario I would throw some forged pistons/rods in,cams and opels, crank the boost on that 256 and let her eat.

 

I think thats on the low end. I do not believe the rods are any different from the lnf vs gen 3 but the gen 3 block is better. So 500 should be do able. Bluelightning broke 400 on a stock gen 3 block and is gonna aim for 500 this summer on a 257

 

Appreciate all the insight. The only thing limiting be from doing it up right is the transmission. I'm not sure I'll have the money to finish the engine build and upgrade the tranny. Scared to crank up the boost and hp on the stock tranny. Iv heard stories of 450+ hp on stock, but that's a little scary. With conservative driving, a good tune, and the 256 being a little smoother boosting, what's a safe amount? Can't afford to break my DD.....

 

Message me again

 

I think the LDK rods are forged like the LNF. The failures with the rods in the LHU builds were attributed to this I believe:
Faulty Connecting-Rod Bearing Causing Engine Failures in GM Four-Cylinders ?*News ?*Car and Driver | Car and Driver Blog