ITR - best option?

[Knestis]

Okay - which of the 3-series sedans is the best starting point for an ITR car, if any have an advantage?

** 325 vs. 328 vs. 330?

** Coupe vs. 4-door?

Assume I know next to nothing about models and features (you'd be right). The car would actually be enduro-focused...

Kirk

[snk328is]

As a general rule of thumb, the E46 has a better suspension than the E36 (330 vs 325/328). The 328 has more torque (but basically same bhp) than the 325 but it's OBD2 and has a more restrictive intake manifold.

As for coupe vs sedan, I've always been told that it makes no difference in rigidity. It might be easier to get in/out of a coupe in the event of an accident though. Somebody correct me if I'm wrong, but I thought I once heard that the sedan has a steeper windshield angle... May or may not affect aerodynamics.

If you decide on E36, it would definitely be worth it to find a non-moonroof specimen if you can, because that would save you the trouble of having to weld the moonroof sheet metal after you remove the moonroof mechanism. I don't know if any E46's shipped without moonroofs.

Then there's the weight thing. I believe the 325 is the lightest of the bunch.

I'm still as green as a noob can get, but from what I've read, it's speculated that the 325 won't be a front runner.

I'm sure Marshall and other seasoned veterans can provide more input.

[JeffYoung]

It will be interesting to see with the existing 325s. With a full blown Sunbelt motor, and at 2700 lbs, they have the power/weight to get it done. They will be SIGNIFICANTLY lighter than any of their competition.

Kirk, I don't know much about the 3 series bodies/suspension, but I do about the motors (used to own an S52 M Coupe). Talked a lot to guys with 2.8 and 3.0 Z Coupes.

I would avoid the 2.8. As noted above, a bit more torque, not much more power than the 2.5.

The 3.0 though, that is an AWESOME motor. 225 hp, gobs of torque.

If it were me, and I wanted to build a BMW racecar, a 330i would be it.

[Andy Bettencourt]

I am far from an endurance expert but I would always think that lighter is better for long distances and duration.

Maybe the best of all worlds might be the E46 325ci at 2800lbs. You get the light weight plus the E46 suspension along with the 200+whp potential. A full 480lbs lighter than the 330's. Would you trade 40whp for almost 500lbs? Boy, I would. Each car will have it's strengths for sure. Yes - that is the car I would build. The E46 325 Coupe from 01 to 02.

I am very sceptical of the guys who say the E36 325 is a midpacker in ITR. The car is light compared to the higher HP cars and can make tremendous power if people prep to the rules. The fact is that when these skeptics look at the initial classification choices, no overdog is apperant. This is the result of being able to design the class using the 'formula' from the very beginning. As in every class, the cream will rise to the top. I would think the E36 and the Honda Challenge Integra Type R's would be at the front early as development work is done.

[dj10]

As a general rule of thumb, the E46 has a better suspension than the E36 (330 vs 325/328). The 328 has more torque (but basically same bhp) than the 325 but it's OBD2 and has a more restrictive intake manifold.

As for coupe vs sedan, I've always been told that it makes no difference in rigidity. It might be easier to get in/out of a coupe in the event of an accident though. Somebody correct me if I'm wrong, but I thought I once heard that the sedan has a steeper windshield angle... May or may not affect aerodynamics.

If you decide on E36, it would definitely be worth it to find a non-moonroof specimen if you can, because that would save you the trouble of having to weld the moonroof sheet metal after you remove the moonroof mechanism. I don't know if any E46's shipped without moonroofs.

Then there's the weight thing. I believe the 325 is the lightest of the bunch.

I'm still as green as a noob can get, but from what I've read, it's speculated that the 325 won't be a front runner.

I'm sure Marshall and other seasoned veterans can provide more input. [/b]

Don't count the 325 out. Remember he's talking enduros. Because of the light weight of the 325 it might make a big difference on tire wear. Saving 1 or 2 tire changes per race might make a big difference. For sprints, I'm picking a 330 over the 325 with 2 good drivers. The advantage of the bigger wheels & tires will help the 330 more. But I'm not going to let them have a easy time of it.

[Andy Bettencourt]

The advantage of the bigger wheels & tires will help the 330 more.

[/b]

I disagree here. 500lbs lighter on the same wheels and tires IMHO is a HUGE benefit to the 325. You know Bimmer's Dan, why would the 330 beneift more? Maybe the 325 can't fit the big guns...

[JeffYoung]

I think he means that bigger wheels and tires will help the grip levels on the heavier car, helping to balance some of the advantage the 325 might otherwise have.

In other words, given 189 stock hp in the 325 and 225 in the 330, on 15" wheels and 7" rims, the 325 can use its power better -- the 330 will struggle to take advantage of its extra power and torque (theoretically anyway).

On 17 or 18" inch, 8.5" wide rims, the 330 has more grip within which to use its power advantage.

I'm with you on lightness though. I just bought a Lotus Exige, and it's amazing what a 2000 lb car feels like even compared to my race car at 2560. The Exige feels lighter and more nimble than our SMs.

This will be interesting. The 325 is essentially the SM of ITR. Light.

[dj10]

I disagree here. 500lbs lighter on the same wheels and tires IMHO is a HUGE benefit to the 325. You know Bimmer's Dan, why would the 330 beneift more? Maybe the 325 can't fit the big guns...
[/b]

I plan to test with 17's, we can fit them. Just looking at the tire patch of what the 330's can have, I'm inclined to say they it will help them. The statement was nothing more than. Look a nascar, they have 3500# cars and they do handle. Put some 15" x 7" wheels on them and see what happens.

[JeffYoung]

Exactly Dan, you said it best. The 330 is better off when both cars are on 17X8.5s. The 325 is better off when both cars are on 15X7s.

[Andy Bettencourt]

I think your point assumes that the 325 is maxed out power-wise with the new-found tire width. That is where I don't follow. You ever follow an light ITA car with the same size tires as you through some twisties?

I guess the only question is whether or not the E36 can FIT huge tires...just another reason why I think the E46 325 will be a GREAT choice.

Any way you slice it, BMW guys have a ton of REAL choices for ITR with the BS of engine restrictions.

[dj10]

This will be interesting. The 325 is essentially the SM of ITR. Light. [/b]

I'm a little excited about next year, already. I beleive if the CRB does away from the antiquated ECU rule. It would make things very exciting for a lot of cars.



Lets not forget about Kirk's orginal post. I was trying to give him something to think about for the enduros next year.

Dan

[Knestis]

Interesting feedback, all - thanks! Backtracking a little, is there anything to choose among the e36 325s? I might actually follow my own best advice and shop ready-to-wear rather than custom tailored...

K

[benspeed]

I wonder if some built but less expensive ITS E36 cars show up plentifully in ITR. It could be the economy way to run the class (not that there ever really is). I also wonder what class ITR might pull from the BMWCCA drivers. JP? I don't know their classes well.

[dj10]

Interesting feedback, all - thanks! Backtracking a little, is there anything to choose among the e36 325s? K [/b]

Yea K, one with a pro cage & suspension. That advise will cost you some seat time when you want to win an enduro.

[Ron Earp]

I wonder if some built but less expensive ITS E36 cars show up plentifully in ITR. It could be the economy way to run the class (not that there ever really is). I also wonder what class ITR might pull from the BMWCCA drivers. JP? I don't know their classes well.
[/b]

JP would be at a higher weight I think, and IIRC JP allows things like non stock cams and non stock throttle bodies. So if you see some JP cars running around you'll have to wonder about legality, but I don't think that would happen if the weights are vastly different.

Looks like a LOT of people are interested in ITR, in fact, some people I thought wouldn't ever consider it too. Good news!!!! Need to find me a Z......

R

[dj10]

I think your point assumes that the 325 is maxed out power-wise with the new-found tire width. That is where I don't follow. You ever follow an light ITA car with the same size tires as you through some twisties?

I guess the only question is whether or not the E36 can FIT huge tires...just another reason why I think the E46 325 will be a GREAT choice.

Any way you slice it, BMW guys have a ton of REAL choices for ITR with the BS of engine restrictions. [/b]

That is where I don't follow. You ever follow an light ITA car with the same size tires as you through some twisties?
Andy, ITA cars are as fast as ITS cars @ Mid Ohio because of the tires and that they don't have to brake as much, or at all. I'm not convinced that the larger tires are going to make a hugh difference.



What are you considering huge? I don't believe that it is the just the width of a tire that counts. There is sectional width, rim size & width and profile. I know what I'm going to start width and for what reasons. As for the power of the 325's, lets start with the E46 325's. It will depend on what type of software that can be programed into the ECU since they don't have chips. That is why the ITAC should make the recommendation to drop the ECU rule as it is and allow EMS. With this we may be able to keep up with the current cars and their newer OBDII ECU's, so we won't be maxed out on the engine.

[Fastfred92]

Who cares what size tire wheel combo??? The e36 can fit a 8.5 as well and power to weight the e46 has no real advantage. The e36 is a more simple car as well ( for enduro's sake ). The 1993-95 coupe or sedan should work fine, it is really your choice. The Bimmerworld guys liked sedans b/c they are slightly stiffer but who knows. I have one of each and maybe a extra donor sedan as well if you go that route Kirk.

[Knestis]

Yea K, one with a pro cage & suspension. That advise will cost you some seat time when you want to win an enduro.
[/b]

Thanks for that! You have 2 minutes of track time credit banked for the VIR 13. More good input and you can have a full lap!

Thank you, too Fred - that might actually be what part of me wanted to hear. We may need to talk if interest in this move for us continues to grow.

K

[Fastfred92]

As for the power of the 325's, lets start with the E46 325's. It will depend on what type of software that can be programed into the ECU since they don't have chips. That is why the ITAC should make the recommendation to drop the ECU rule as it is and allow EMS. With this we may be able to keep up with the current cars and their newer OBDII ECU's, so we won't be maxed out on the engine.
[/b]

I am pretty sure you will have no choice but to go Motec with any OBDII to get max power. I think you can get real close to max without Motec in a OBDI car, you may leave 5-10 hp on the table but you will not be very close with a OBDII car without it. WIth the e46 double vanos you will need a upper end ( read $$$$ ) Motec unit like the M600 to get the most out of it. You will also spend as much having someone put that unit inside the OEM box as you did on the unit ( stupid rule )not to mention programming and dyno cost. You could build a very fast 98% build e36 and have alot of fun without spending as much on your fuel injection box as you did on your tow rig.

[Z3_GoCar]

Vic Sias at Sias Tunning make a kit to stuff an Electromotive TEC III into the stock BMW case. The TEC III allows configurable sensors and actuators too, unlike my TEC II system which is limited to certain sensors and a custom wiring harness. Step up to the latest technology and pay the price for the ability to tune the system without going through Confoti's one size fits all shark injector routine that's avalible for the stock computer software download. OBDII is such a crock, it basically undose any mod's made on the engine to make more power. How would the carb/points guys like it if every time they rejet the carb and adjust the timing to make the power they can get, then it all gets undone automatically?? I say allow us to just s-can the whole OBDII system and replace it with anything that uses the stock air metering system. Simple fact OBDII doesn't belong on a race car.

James