Hello all,
I am putting this post out in hopes that I can get some feedback from our community on their experiences and feelings on the r53 power plant. Specifically if you had the motor completely apart and were rebuilding, what area would you look at improving to gain more HP.
To start with, and why I am writing this post, I have a 2003 r53 that was damaged during what seems to be a very low oil run during an SCCA autocross event. The low oil condition starved the bearings on the connecting rod of the number 2 cylinder, thus causing a catastrophic engine failure as it spun those bearings. Once the engine was completely apart we noticed issues with the SC and delaminating of the blades (mine was the coated blade version), also a huge amount of oil in the SC itself, as well as a fine mist of oil on the front of the block underneath the intercooler duct. Now after reading several posts I decided to send my SC off to get rebuilt, since over 75k was on it and the obvious delam. The cylinder walls and pistons all seemed to be in good to very good condition. The only issue was the number 2 did have some “scrapes” on the skirt, but that was all. They are very minor and not what I would say was a gouge. The head was undamaged and received no blows from the piston. The worst news was the Crank. It was bent to far out of tolerance to turn it down. So that is the largest component being replaced.
So here is what is going back in
New stock connecting rods
new rings
new bearings including guide bearing
new crank
Alta lighten crank pulley,
OBX header with OEM Cat
Modified stock oilpan with baffle (to prevent oil from loading one side)
And of course all new gaskets
I have also got the spec clutch, flywheel and the Quaife LSD to go in as well

Now the question. What would you do? What I mean by this is if you had a chance to improve the performance of your engine while it sits out and ready to be put back together? The head? The pistons? I want to stay in the STX class, so porting, pulley diameter, cam change, all are out, but is there anything, while this is apart, you have learned from your own experiences that you would have done?
The reason I am relying on NAM is because I do not have a Mini performance shop in my area, nor did I find a normal car shop that would even look at my car, or help guide me. So I have enlisted a race shop that has done most of the work. However since I am located in the circle track south, they are used to dealing with very large and very angry looking motors, that have more than 4 cylinders. So they were nice enough to help, but they also are concerned we are not doing enough when putting this back together.
Thanks for reading

 

2 options

1. RMW 2.0 crate motor

2. Built Motor - Pistons, rods, and head

 

I have no idea, but wonder what people will come up with that will keep you in STX. As far as I can tell, that just means rebuilding very strictly to factory tolerances best as possible.... Might want to query the STX forum also....

 

But what the SCCA officials don't see won't hurt them especially if you go forged pistons and rods they won't give you anymore power just extreme durability.

 

*shrug* cheating is lame imho.

 

I second that . Dont go back to stock imo, build it up, or 2.0 FTW

Jack

 

+1
What's the point in beating someone when you know you have an obvious advantage over them? Plus its gonna feel even crappier when someone comes along with no advantage and whips your tail even though you do have an advantage.

I don't know enough about the scca rules on modifications (I do hope to start autox this summer) but it seems like forged pistons and crank would put you in a higher class, even if it didn't give you that much more power.

 

I would have the whole reciprocating assembly balanced for what you are using.

Your machine shop will need the crank pulley, crank, rods, rod bolts, rod bearings, pistons, rings, flywheel, flywheel bolts, pressure plate, pressure plate bolts and clutch disc to balance the assembly correctly.

 

factory motor has sand cast pistons, factory forged rods(capable of 300-400hp), forged crank (unknown limit). Putting forged pistons, and better rods in the motor are not power adders they reinforce an already very well built motor. I see no way having far more durable internals then stock is cheating in competition other then your motor won't pop and because with the proper forged internals which brings in the fact about AutoX or any racing type the car is put through some harsh treatment and by doing all aftermarket forged internals your saving yourself a ton of money in the long run which is not cheating at all.

 

You can rationalize it any way you like, but the SCCA rules are VERY clear about what you can add/modify in each class. They're also very explicit that if a mod/replacement is NOT mentioned in the rules for a particular class, than that mod/replacement isn't legal for that class.

At the very least, forged replacement pistons are likely going to be lighter than the cast factory pistons, and who's to say that the static compression ratio wouldn't change slightly with the new pistons? Both of those could give you a performance benefit, however small.

Look at the 2008 rules - "Stock" Category specifially disallows swaps from cast to forged pistons. "Street Prepared" allows the use of forged replacement pistons even when the factory pistons are cast, but the forged pistons *must* weigh at least as much as the factory pistons, and must be dimensionally-identical as far as the shape of the dome/quench area is concerned.

The lowest class that allows swapping in lighter pistons and alternate connecting rods is "Prepared", so that's where the mods you're talking about would put you.Classing is determined by the rule book - it's not up to the individual competitor to decide whether a particular mod gives a performance benefit or not.

 

.

 

Thanks so far.

Yes i believe the changing to forged piston and crank would be an issue, however i believe the rules do state that you can replace with same type of part, so since it is the same shape but different material might be issue.

Though the forged pieces would strengthen the engine, would it be a noticeable gain in performance for the cost? That is the question, even if was allowed by rules. Are you going to see a difference with all forged internals balanced, versus replacement stock cast internals? Maybe if you were making a high boost engine, or a track engine that fully wound out the crank, but with short bursts in autox, would it really matter?

This is the same debate i am having currently with my engine guy. He is saying well no, but again he deals with Big Volume engines, not 1.6L fours. They look at titanium and other interesting exotics. In fact he mentioned getting custom made connecting rods, then he told me price…. Needless to say I have factory replacements.

Again please keep up this great discussion; i am interested in seeing if this ends in any real conclusion.

And for the record, I do not want to cheat, even though it is highly unlikely my motor will ever be stripped down in my area, i would know and that would bother me a lot.

 

My bad Scott I wasn't aware of how much of a stickler the SCCA rule book was on what can and can't be done to keep the car with in a class.

 

If the factory components are capable of amazing power, as they certainly are, then why shell out the money for stronger components? Durability, fine. If the OP really wants to spend money. But running low on oil will still grenade the thing, as will downshifting and revving it way past the redline, as I've seen happen to an R56 autocrossing. Properly kept, the stock components will last a looooong time autocrossing as it's not that terribly hard on the car ('s powerplant, at least). I don't see a particular weak link here, and Partsman has offered the best advice imho.

If I was in the OP's position? I would definitely build the motor. But I'd move into the proper class and not stay in STX. Classing at local events is largely a matter of good faith, so don't go squandering it. (imho, no drama meant.)

 

I have 51k miles and lots of high and low rpm rev matched downshifts. The stock rev limiter is low but if have a tune, head and injectors to facilitate the higher RPM's you can make the redline 8K rpms.

 

Classing in my neck of the woods is very nonchalant, and never checked, unless you're the top dog, and advance to the regionals or nationals.

Are you that good/serious about advancing, to where this scrutiny would take place?

It's up to you, but I would personally look at this incident as a golden opportunity to build the **** out of this motor from the inside out, including new forged pistons, rods, a new RMW head and cam, etc.

Unless you're really pursuing a national SCCA autocross title, why limit your car's performance/fun factor to adhere to the SCCA rulebook, while sacrificing a more fun ride every other moment of driving?

It's okay if your MINI is truly just for autocrossing, but if you use it as a daily driver, or for fun runs/rallies with your other MINI friends, why limit it?

 

AMEN Jon

 

There's no reason why you can't "build the ****" out of a car and still autocross it - just don't try to compete in a "lower" class than your car should be in. Go wild with the engine if you want to, but don't turn around and then try to run in Stock or STX when you should be in DSP or Prepared.

I'd love to put a supercharger pulley on my car, but I don't want to run in SM class, so I'm skipping the pulley for right now because I enjoy being competitive in STX. I may add the pulley at some point in the future, and when I do, I'll switch to SM the same day. (And go with the M7 USS and some R-comp tires at the same time).

So, you don't have to choose between autocrossing and modding the car any way you want to for everyday enjoyment, but you shouldn't be trying to "have your cake and eat it too" by modding the heck out of the car AND competing in one of the lower classes where those mods aren't allowed.

If you want to compete in the lower classes, limit your mods to those that are allowed in those classes. If you want to go wild with the car, then go for it, but when you're done, suck it up and class your car appropriately.

Whether or not anyone is actually going to inspect your car is beside the point - like the saying goes, "Integrity is what you do when no one's watching".

 

Jan's valvetrain is good up to about 10k RPM's. I believe the limitation on the stock motor relates to rockers. I've had my motor up to 8250 RPM's on numerous occasions with no valve float. Most of the cars Jan's tuning now are getting 7600 RPM redlines with his head.

The power difference is neglegible, and the only benefit is during competition. Being able to ring out the motor for another 3-4 seconds can mean the difference between a successful pass and the necessity to shift (failed pass).

 

Well said Nick

 

I have a shop on the NE side of Atlanta.

Way Motor Works
5410 New Peachtree rd
Atlanta GA 30341

If you been running STX you've prob seen our Pepper White R56 at the SCCA events.

 

word. If i were you i'd pay off the race shop for the work they have already done... put your car on a flatbead and send it to way. He knows mini's, he's a hell of a guy and chances are he'll be cheaper.

Now if it were my car. I would have used this as an excuse to go all out. Why try to stay in stx? I mean autoX is fun and all... but if this isn't a trailer queen and actually gets driven often... then the answer is clear, pistons, head, injectors, tune. and drive the **** out of it.

 

Be sure to seat the piston rings well.

 

[QUOTE=minimusprime;2215915]word. If i were you i'd pay off the race shop for the work they have already done... put your car on a flatbead and send it to way. He knows mini's, he's a hell of a guy and chances are he'll be cheaper.

what he said.