Is an LS swap really the answer? Help me decide.

This was a sad weekend.

I'm reasonably certain the G35 spun a rod bearing coming out of turn 12 at CMP this weekend with my wife behind the wheel. We were putting back-to-back sessions on it and it was more than she could stand. I noticed it running a little warm in my session and pulled it in early to give it a chance to cool down some but that didn't save it in the end. I'll pull it in the next month or so to be sure but I'm reasonably certain the crank is wiped. It's time to make some decisions. 

My plan has always been to LS swap it when that happened. Done deal. More HP, more torque, just more. A 400+hp beast. It's a great plan and seems like the easy button. But, sitting down and working the numbers, it also more money. Like a $10k+ by the time the dust settles. Probably more than that because I will want to keep the A/C and have a nice street-able car when I'm done. I have zero interest in driving a caged-out and gutted track rat. I want to be able to sit in grid with the A/C on or drive it through the mountains in comfort. 

So I started looking at the possibility of staying with the VQ. A replacement engine is around $1000. Add a couple of hundred to go through it and change the bearings and rings, call it $1300. The VQ is apparently happy with some boost so I could also add a turbocharger kit for about $3k and hit the 400hp mark fairly easily. This plan has a couple of advantages. One, I can get the car up and running in a weekend with the replacement engine. Two, I can add power boosters it over time as long as I have a well-built block to base everything on. 

Discuss. Which way would you go and why?

Thanks. 

What's the plan for managing the heat that a power adder would add? Particularly for an on-track application? more cooling needed at that point? Venting bodywork?

There may not be much of a difference between an LS and a VQ+boost on the street, but I think the differences would show up after a long, spirited drive or a handful of laps on track.

Fix it back to what it was and flog it some more; just upgrade the cooling system.

The sloppy mechanics guy is selling his LS swapped G35 with the LOJ kit. Might be easier (maybe cheaper) to buy it and transfer your goodies than do it yourself.

The current cooling system has been doing the job. It has an oversized radiator and a decent oil cooling system now. Track temps are usually very stable. I should have told my wife to watch the temps. By the time I got to the car it had been sitting for a while so I don't know where the temps ended up or even if it was overheating at the time of failure. It's still topped up on oil and water. It may be the engine failure is just a combination of frequent 7000 rpm shifts and lots of mileage. 

I'm not above venting bodywork or adding more cooling as needed. 

Is class or competition a factor? 

How much do you want a project right now?

My first thought was cooling as well. Just because the current stuff has worked with it NA, it's unlikely to be adequate for forced induction. 

LS swap, or a PROPERLY boosted VQ are likely to be more than you want to spend. I'd probably just drop in a good used engine and keep beating on it. 

Having been down the road of a LS swapped FD RX7 I can confidently say just stick a VQ back in it. It sounds great on paper but it never makes sense financially enough to justify the engine swap. The FD was a little different because I wasn't a rotary fan and just loved the chassis so it almost had to be done (sorry rotary lovers). If I were you I'd definitely do a mild build on the VQ like you suggested and just throw another back in. Add the turbo later if you're itching for more power. I don't know your skill level using a wrench, but swapped cars aren't as friendly to work on generally(not comparing to the turbo added). 

All that said, if you want something a bit different a do want the LS power and can justify the $10k+ than totally do it. Tons of people do it and totally love it and  you might just love it. I just learned it wasn't necessarily for me.

Sorry to muddy the water but I'd just stick with VQ if I were you. 

Edit: I agree with Z31 above, both sound really expensive and you might be better off sticking the $10k-20k into something else IMO.

How about the nissan 5.6 or the oem Turbocharged 6 cyl options?

I'd start with the ultimate goals, and then figure out how to get there. If you'll be pushing the limits of the VQ to get to your goals, it may be cheaper to just go LS from the start. Bigger up-front cost, lower overall. There's the reliability question as well, a stock LS with stock drivetrain components is understressed and just hanging out waiting for stuff to get difficult. A pressurized VQ may not be.

I figure the crossover point for costs in the Miata world is about 350-400 hp because of what it takes to get there with the original engine, but even at that crossover point I would expect the LS car to be more reliable. With my MG, the crossover was probably about 200 hp :) The math will obviously be different for the VQ because it starts with a bunch more power, I don't know anything about the rest of the drivetrain.

An LS swap is really going to bork me from a TT standpoint. I run in Sport 3 now. Saturday afternoon before the engine popped, I was in P1 out of 4 cars. 

An LS swap will push me into Max 2 where I probably won't be competitive without more mods to support the extra grunt. 

The turbocharger will push me to Max class as well. 

More things to consider. 

In reply to Toyman01 + Sized and :

In my opinion, none of that matters unless you are actually trying to win something. Back to the goals thing as Keith pointed out, if you are just in it for fun do whatever you want within the budget you set. Wanting the car to stay street-able and continue having creature comforts points in the direction of not really caring about winning too much and sounds like more of an enjoyment for you and your wife. 

As you said, much to consider.

In reply to JAdams :

In Sport class, you can have all those comforts and still be competitive. In Max that won't be the case. 

It's always the right answer 

In reply to Toyman01 + Sized and :

So then it boils down to, do you want to be competitive in Sport or Max? If the answer is Max, are you willing to spend the necessary money? What other mods besides the drivetrain are you going to have to make? If not Max........throw another VQ in there and keep having fun. 

In reply to Toyman01 + Sized and :

Sounds like you maybe just made the decision then. You want all those comforts and can't have them if you turbo or LS because that will push you into Max and you won't be competitive. VQ replacement here we come!

In reply to z31maniac :

Yeah, that's the direction I'm leaning. Built well and optimized within the ruleset and run it until it dies again. 

100% LS swap all the way, but using the kit from LOJ. It's pricey, yeah, but it's also the only swap kit I've ever seen that actually results in a turn-key "drive to work with the A/C blasting while not even thinking about the engine" result. I'm still shocked at how easily our LS-swapped 350Z came together.

Tom Suddard said:

100% LS swap all the way, but using the kit from LOJ. It's pricey, yeah, but it's also the only swap kit I've ever seen that actually results in a turn-key "drive to work with the A/C blasting while not even thinking about the engine" result. I'm still shocked at how easily our LS-swapped 350Z came together.

The evidence is right there.

Just fair warning... the cheap LS (5.3L) is going to be pushing 500 lbs fully dressed compared to the VQ at around 300 lbs.  The power and torque will more than overcome that weight, but just thinking you might have extra dollars in suspension changes to keep you inside the cones.

The other thought is... pull the pan.  It might not be that bad.  Dress up the crank and do a 10-under bearing on that one.  $150 in machine work and parts.

Another option is to replace your VQ with a known good one, then fix the bearing at your leisure and sell it to recoup some of your cash.

Engine swaps are much harder to do  than you would think. Pretty much have to do one to fully appreciate what it takes to do and do well.

NOHOME said:

Engine swaps are much harder to do  than you would think. Pretty much have to do one to fully appreciate what it takes to to and do well.

The best reason to do an engine swap is because you want to do an engine swap. 
If you look at it logically it doesn't often make a lot of sense. 

It's hard to beat oem level engineering.

NOHOME said:

Engine swaps are much harder to do  than you would think. Pretty much have to do one to fully appreciate what it takes to to and do well.

But I read on the internet...

Engine swaps I've done, while not particularly hard they are time-consuming. Getting the LS electronics to communicate with the G35 dash would be hard. That is also one of the reasons I'm leaning toward fixing the VQ. Replacing the VQ will cost me a day or two. An LS swap would take months. 

While the LOJ kits look awesome, I'm not spending their kind of money to do the swap. 

In reply to Curtis73 (Forum Supporter) :

Yeah, I was looking at the weights today.