LSx engine swap for track use, thread

[scudzey]

Originally Posted by foodman

Would a wide body and gt wing really be required/nessecasry though?

The width of an FRS and a C7 is very similar (70" vs 74" respectively..C6, even more similar at 72").

Tires would be the biggest concern for traction. But, you can easily fit 245-265 tires under a stock body FRS. Question is, will 255 be enough for 450whp?? Prolly not huh?

GT wing...I'm not sure this is required unless you're looking to hit top speed records, or have a real racecar. Yes, 450hp will be much faster...but, there are also many with FI FA FRSs with no huge GT wing.

To me, it sound like makin it track ready would be not much different than your current/regular FA FRS. The biggest concern is getting that power down with sufficient tires and if 255-265 would work. Everything else would be the same correct? - wheels/tires, suspension bits and coilovers, bbk, and that's pretty much it.

The wide body would primarily be to support the wider tires. The stock c7 has 285 tires in 19x10's in the rear. I haven't looked at the clearance in too much detail to see how much you can squeeze under there with the stock body, but I was looking at getting 300+, which was driving me to those WB kits.

Biggest concern is getting the power to the ground, and very closely behind that is keeping the suspension in check to prevent that understeer/oversteer issue.

[foodman]

C7 has lateral grip of 1.03-1.11g (depending on reviewer/tester). This sounds quite high and capable.

I'm pretty sure an LSx FRS with mild/medium suspension mods (ie: just replacement parts) using stock pickup points and stock suspension geometry/design cannot reach this, correct?

[Celadrielas]

@Cross Is going through this process I believe, and may have more opinions or experience with this, but I believe this would vastly changed the balance and power to weight ratios of the vehicle unless you were able to do / construct something like the old Porsche's used to run, where the transmission is in the rear of the vehicle.

Cross, Have you decided on doing this? If so, are you wagering any fitment issues, and if so, how do you plan to resolve? Any fears with too much forward weight making tail wag? Do you have any ideas on how to fix potential balance issues?

EDIT: After reading through everything more closely, there are a LOT of relative points here which are important on the street as well. Situations such as snap oversteer could be potentially dangerous in conditions you don't commonly see on a track (like rain or snow) and additionally, putting all that power to the floor safely would be a feat of engineering which is not out of reach. WB kits, as well as "Tubbed" rears (Think how they handled this sort of thing with american muscle) would allow for bigger tires, but would also potentially complicate camber / clearance. Wider in the rear doesn't require wider in the front and lateral grip force of the tire tread would matter significantly more on a track than on a street but would still be important to ensure proper stopping distance. -- Which also includes bigger brakes.

Remember it's not enough to just go fast, but stopping that speed matters too and Brakes are the last place to chince out. So the true question should be what do you want OUT of the vehicle. Then you can better decide what to put IN to the vehicle.

[SomeoneWhoIsntMe]

a buddy of mine swapped an LS1 into an absolutely gutted NA miata. he's VERY happy with it relative to the turbo 1.8l motor it replaced.

[ame="https://www.youtube.com/watch?v=ePNAX5x-2lM"]LS1 Miata hits a Waterford HIlls track day. IT'S MURRDAAAA - YouTube[/ame]

it's his opinion that an even static weight distribution is nice to have, but when you can tune the effective weight distribution with aero etc, it's not the end of the world to have a front-heavy or rear-heavy car.

he's also running a conservative wheel/tire setup under stock fenders and he hasn't died yet. I'm sure that old miata is a damn sight lighter than a BRZ would be, and I believe it's also even more limited on tire sizes. you can drive around it, and the motor is torquey enough that you don't give up much speed in doing so.

I know it's not a BRZ, but I figure it's a decent data point.

[dradernh]

Go to a race shop that builds successful road race cars and ask them what they think it would take to make it work. They'll have most if not all of the answers you need, including to some questions you didn't know needed to be asked.

I considered putting an LS3 into my E36 M3 race car, discussed it in detail with my race shop, and the only real issue was...wait for it now...money. Big surprise, right? Of course, the car was already fully developed, including major aero. Putting the power to the ground certainly wasn't going to be a problem!

You can get away with 265s with that power. It's a track car, not a car that you're going pro racing with. However, the more developed the car becomes, and the better the nut behind the wheel becomes, the more the car will need the widest rubber that can be gotten up to temperature - if getting every last second out of the car is that important. By that time, you'll be club racing, and it will be a different conversation (e.g., series rules, even more money, etc.)

That said, I think the whole understeer/oversteer thing is a non-issue - you'll build the car properly, and it will have the precise amount of oversteer you need to make the car work for you. That's a given.

My 2¢ - as always, YMMV.

[Reaper]

Let me first start with saying im going to put an ls into my frs at some point. I got the car with the intent of building one fa20 and running it until it needed a rebuild(and my LS engine was completed over the coming years) and then putting an LS in it and keeping the car as a toy forever.


Im near 390 wheel torque at 4500 rpm with 245 tires and the car is very hard to drive fast on tight roads. I really need rampable boost and per gear boost to be even remotely quick in the corners in any gear below 4th. With a LS that makes the same amount of torque 3000rpm sooner and substantially more at peak it will be impossible to control without active aero and some enormous for the car tires. When I was gutted on high boost I was near(possibly at/over) corvette zr1 power to weight and without zr1 tires and weight and aero it was violent to drive. Fun but not a competitive track car. Remember a zr1 has 335 rear tires. That's about 4 inches wider than what a lot of us have, and with more weight on it and a stiffer more stable wheelbase.
Im all for a v8 frs I truelly am. But lets not forget what that turns this car into. It makes it a hoonning machine, a drift car, a toy, violent...etc. I doubt you could get one to turn competitive track times. An its not really because of the weight which is a non issue if you do your research. What it comes down too is if shortening and lightening the corvette chassis and making it essentially an frs was faster, gm would have done it. There's a reason that car is that weight and size.(within reason, they obviously could cut some creature comforts out im talking big picture)

[foodman]

Originally Posted by dradernh

Go to a race shop that builds successful road race cars and ask them what they think it would take to make it work. They'll have most if not all of the answers you need, including to some questions you didn't know needed to be asked.

I considered putting an LS3 into my E36 M3 race car, discussed it in detail with my race shop, and the only real issue was...wait for it now...money. Big surprise, right? Of course, the car was already fully developed, including major aero. Putting the power to the ground certainly wasn't going to be a problem!

You can get away with 265s with that power. It's a track car, not a car that you're going pro racing with. However, the more developed the car becomes, and the better the nut behind the wheel becomes, the more the car will need the widest rubber that can be gotten up to temperature - if getting every last second out of the car is that important. By that time, you'll be club racing, and it will be a different conversation (e.g., series rules, even more money, etc.)

That said, I think the whole understeer/oversteer thing is a non-issue - you'll build the car properly, and it will have the precise amount of oversteer you need to make the car work for you. That's a given.

My 2¢ - as always, YMMV.

Vorshlag - they have all the things you mentioned - they build road race cars, they've been using the LS1 swapped into much lighter cars for 10+ years (including your e36)...so if anybody, they def know how to make it work. And they are currently building a bolt on kit for the FRS ...hence this post

I read the stock C7 uses PSS 285 in the rear stock...which doesn't sound too different than a 265 RS3 or ZII and would be pretty darn close, if not better than a 285 PSS. If serious about grip...there's always R-compound

[foodman]

Regarding oversteer/understeer...wouldn't this be relatively easy to sort out and fix with coilover damper tuning, spring rates, sways, etc?? ...in other words, what everyone has already been doing and experimenting on already for forever. Simple coilover tuning - I don't see why it wouldn't be the solution.

[foodman]

If anyone hasn't already read this...here:
http://www.vorshlag.com/forums/showthread.php?t=8275

They seem pretty darn competent, experienced and knowledgeable in the road race, autocross, closed-circuit, track game if you ask me

...they also only deal with quality or real competition coilovers - AST, MCS, Moton, JRZ, Bilstein, etc... Which is a good indication they're focused on and serious about track use.

[totopo]

Originally Posted by foodman

Regarding oversteer/understeer...wouldn't this be relatively easy to sort out and fix with coilover damper tuning, spring rates, sways, etc?? ...in other words, what everyone has already been doing and experimenting on already for forever. Simple coilover tuning - I don't see why it wouldn't be the solution.

balance isn't that simple. When you mess with balance with suspension, you usually end up with decreased overall traction because of exaggerated weight shift on one end. Also balance isn't just static, depending on braking, accelerating, yaw rate it changes. There are so many factors, like corner weights, suspension geometry, roll center, alignment, lsd, that makes it really complicated.

[foodman]

Originally Posted by totopo

balance isn't that simple. When you mess with balance with suspension, you usually end up with decreased overall traction because of exaggerated weight shift on one end. Also balance isn't just static, depending on braking, accelerating, yaw rate it changes. There are so many factors, like corner weights, suspension geometry, roll center, alignment, lsd, that makes it really complicated.

Yes..very complicated indeed.

But...the LSx swap would only be 40lbs difference.

Wouldn't the big power characteristics and downfalls be more of a concern than suspension geometry? It surely wouldn't be a "momentum car" anymore and will be transformed into a "power car."

[foodman]

@Reaper::

Sounds like a handful indeed, to say the least.

You think an NA LSx would be easier to drive than your current car though? It is after all NA and has a linear powerband ...not to mention stock engine characteristics

[mav1178]

Originally Posted by foodman

So, so far, general consensus on the track forum and by track heads is, nay.

The problem here is, we have no idea what you are capable of as a driver.

Will the change in CG make a difference?
What is your end goal? Track?
What about a LS swap is better than a turbo (or nonturbo) FA20?
What budget?
Why?
Which track are you driving on? Top speed? Drift? Lower speeds?

Don't be worried about suspension and putting power down to the ground just yet. The basics of why you need an engine swap has yet to be answered.

-alex

[Sleepless]

Originally Posted by foodman

C7 has lateral grip of 1.03-1.11g (depending on reviewer/tester). This sounds quite high and capable.

I'm pretty sure an LSx FRS with mild/medium suspension mods (ie: just replacement parts) using stock pickup points and stock suspension geometry/design cannot reach this, correct?

The lateral grip is measured at a constant radius circle on a skid pad. There isn't much correlation to driving into and out if a corner. The weight transfers are dynamic vs static on the skid pad.

Note, that I'm assuming you want a superb track car that you want to drive close to 10 / 10ths. To do that it will be a lot of work and suspension tuning.

People greatly under estimate what it takes to make a powerful and great handling car. As a point of reference, I've driven with other FT86 owners that have upgraded their cars in the pursuit of improving their cars to only find they are slower or haven't improved anything.

Add to the complexity of suspension tuning a heavier engine that makes a LOT more torque and you've considerably made it more complex of a project.

If on the other hand you just want to do and interesting project to play with, then yeah, dropping in an LS is a fine project. Just don't be surprised to have a well driven stock FT86 catch you on the twisty bits!


Sent from my iPhone using Tapatalk