E30 configuration to be competitive in GLTC

[FredK]

I saw a post by moatilliatta in another thread where he said he might try out Gridlife GLTC next year with an S50 swapped E30.

Opening up the discussion to everyone, what configuration do you think might be competitive in GLTC? Engine, suspension, aero, tire/wheel package?

To me, it seems like the optimum configuration will involve flares and as wide an RT660+ as possible. What's the tire you think would be optimal? Also, since this sort of goes hand in hand, what would be the suspension configuration? E36 5 lug with 9.5"+ wheels?

I think Digitalwave tried out his E30 in GLTC with a stroker M20 stock plastic bumper late model, but I could be wrong.

[JasonWilson48]

LS with Tremec(or go m50 turbo with oil cooler), any suspension that pushes your track out (GC or E36/z3 5 lug) a bit but add bump steer correction, stiffer sway bars, strut bars, short geared LSD that keeps you in rev range, z3 rack, camber plates, flat undercarriage, splitter, wing, cut the fenders and go as wide as you can with 16 or 17 inch wheels to fit some BIG ol' brakes under there. Any 200 TW performance focused tire.

a bunch more, but that is what I'm thinking to start

[craz azn]

I saw a post by moatilliatta in another thread where he said he might try out Gridlife GLTC next year with an S50 swapped E30.

Opening up the discussion to everyone, what configuration do you think might be competitive in GLTC? Engine, suspension, aero, tire/wheel package?

To me, it seems like the optimum configuration will involve flares and as wide an RT660+ as possible. What's the tire you think would be optimal? Also, since this sort of goes hand in hand, what would be the suspension configuration? E36 5 lug with 9.5"+ wheels?

I think Digitalwave tried out his E30 in GLTC with a stroker M20 stock plastic bumper late model, but I could be wrong.

I pondered this exact subject ad nauseam for years now. And I never pulled the trigger on it for a few reasons. One... the performance ceiling in GLTC is pretty high. When you compare an E30 to any modern chassis (lets say E36, or E46 as a direct comparison for arguments sake), you fight against a few things, relatively speaking, mostly to do with the rear suspension design. Unstable under braking (maybe partly to do with short wheelbase), and tough to put power down out of a corner (newer chassis' can do this much more effortlessly). Front suspension is luckily not a major consideration, as we've seen E46s be successful in GLTC (And the e36s that have were mostly widebody) and all three generations of 3 Series are somewhat similar in geometry. Wheel size/width is also a consideration (as you touched on), as well as the general footprint of a car (a widebody E30 barely equals a stock E46, so right away theres a deficit). Tough to fit wider than 9s on an E30 without cutting it up... whereas 10s and beyond are easy on the newer bigger cars. Another thing, Aero is also a consideration too... as an E30 is probably one of the worst choices for that in GLTC, sans maybe that widebody AE86. All the other cars are much more slippery/smaller frontal area to deal with.

I'd probably be building an E90 for the series if somebody handed me a bunch of cash tomorrow and said build me the best BMW you can...

That said, I think the only way an E30 could be (barely) competitive is play on the lighter side of the rulebook ie light car, less power, smaller wheels (15s), modern ABS, modern shocks (MCS DA at a minimum) and have it powered by an aluminum block 6 cyl of some sort, standalone ecu to exploit the engine as much as possible (possibly DBW to enable more tune options), and try to come up with a clever solution as far as gearbox ratios are concerned to keep the car the car in the powerband like the Honda guys can (for me, if running a BMW engine, I'd be trying to source and adapt a Getrag E30 M3 Group A gearbox, as its still an 'oem transmission' and not something exotic aka dogbox which isn't eligible as per rules, last I looked (early 2025).

[FredK]

I pondered this exact subject ad nauseam for years now. And I never pulled the trigger on it for a few reasons. One... the performance ceiling in GLTC is pretty high. When you compare an E30 to any modern chassis (lets say E36, or E46 as a direct comparison for arguments sake), you fight against a few things, relatively speaking, mostly to do with the rear suspension design. Unstable under braking (maybe partly to do with short wheelbase), and tough to put power down out of a corner (newer chassis' can do this much more effortlessly). Front suspension is luckily not a major consideration, as we've seen E46s be successful in GLTC (And the e36s that have were mostly widebody) and all three generations of 3 Series are somewhat similar in geometry. Wheel size/width is also a consideration (as you touched on), as well as the general footprint of a car (a widebody E30 barely equals a stock E46, so right away theres a deficit). Tough to fit wider than 9s on an E30 without cutting it up... whereas 10s and beyond are easy on the newer bigger cars. Another thing, Aero is also a consideration too... as an E30 is probably one of the worst choices for that in GLTC, sans maybe that widebody AE86. All the other cars are much more slippery/smaller frontal area to deal with.

I'd probably be building an E90 for the series if somebody handed me a bunch of cash tomorrow and said build me the best BMW you can...

That said, I think the only way an E30 could be (barely) competitive is play on the lighter side of the rulebook ie light car, less power, smaller wheels (15s), modern ABS, modern shocks (MCS DA at a minimum) and have it powered by an aluminum block 6 cyl of some sort, standalone ecu to exploit the engine as much as possible (possibly DBW to enable more tune options), and try to come up with a clever solution as far as gearbox ratios are concerned to keep the car the car in the powerband like the Honda guys can (for me, if running a BMW engine, I'd be trying to source and adapt a Getrag E30 M3 Group A gearbox, as its still an 'oem transmission' and not something exotic aka dogbox which isn't eligible as per rules, last I looked (early 2025).

I agree, I think the light car, less power is the only way to really be in the mix but not ever win lol. It seems like the fastest cars are definitely running flat tunes. I think something like an N52 will have a very wide powerband, so you don't have to shift a ton, and you can be in the powerband a lot. I don't have designs on running in GLTC, but my club's largest, most competitive class is GLTC, and it'd be fun to run with them. Just my misguided feeling, but I feel like sub-200 whp would be a better spot than over 200 whp, though it's been proven time and time again that weight isn't much of a penalty, not having power is, so porking up an E30 to be fairly heavy and having power is probably the way to go.

[craz azn]

I agree, I think the light car, less power is the only way to really be in the mix but not ever win lol. It seems like the fastest cars are definitely running flat tunes. I think something like an N52 will have a very wide powerband, so you don't have to shift a ton, and you can be in the powerband a lot. I don't have designs on running in GLTC, but my club's largest, most competitive class is GLTC, and it'd be fun to run with them. Just my misguided feeling, but I feel like sub-200 whp would be a better spot than over 200 whp, though it's been proven time and time again that weight isn't much of a penalty, not having power is, so porking up an E30 to be fairly heavy and having power is probably the way to go.

I'm intrigued but not convinced that the heavy approach for an E30 would work. I think the rear tires would get overwhelmed too quickly, just purely based on the geometry of the rear suspension. As an observation in the live streams, it seems like the E36/46s can't put power down as well as the other platforms can (FRS/BRZ, S2K, etc)... and theres no way an E30 will best an E36 or E46 for corner exit.

Also, the cars using the heavy approach are big cars (vettes, 370z, etc)... they are better able to distribute their mass over the tires, which helps not overwhelm the tires over the driving stint. I don't think an E30 with a smaller footprint (even with an extreme widebody/big tires) can handle it as well as a bigger, stock-designed car.

As an outsider looking in, I don't know exactly on how flat tunes are penalized anymore, as blatent flat tunes definitely get a percentage modifier, but if you make it 'look' like a natural power curve, they let it slide? That would be a good question for somebody participating in the series Digitalwave

[FredK]

I'm intrigued but not convinced that the heavy approach for an E30 would work. I think the rear tires would get overwhelmed too quickly, just purely based on the geometry of the rear suspension. As an observation in the live streams, it seems like the E36/46s can't put power down as well as the other platforms can (FRS/BRZ, S2K, etc)... and theres no way an E30 will best an E36 or E46 for corner exit.

Also, the cars using the heavy approach are big cars (vettes, 370z, etc)... they are better able to distribute their mass over the tires, which helps not overwhelm the tires over the driving stint. I don't think an E30 with a smaller footprint (even with an extreme widebody/big tires) can handle it as well as a bigger, stock-designed car.

As an outsider looking in, I don't know exactly on how flat tunes are penalized anymore, as blatent flat tunes definitely get a percentage modifier, but if you make it 'look' like a natural power curve, they let it slide? That would be a good question for somebody participating in the series Digitalwave

Haha, I was playing with a GLTC calculator and started daydreaming. What I meant was, in between the two lowest power classes, the heavier/more powerful option, like a 230 whp car, 2703 comp weight, natural powerband, 245mm tires, might be preferable vs. a 199 whp car, 2289 comp weight, natural powerband, 245mm tires. That's just going on vibes though, no laptime simulator or anything haha. The calculator I'm using may not be accurate, as it's from a classing spreadsheet from my local club that runs a GLTC class. But, folks from the club do run in actual Gridlife events.

I definitely don't think that a detuned LS E30 at the same curb weight as that GLTC C5 Corvette would be anywhere close, especially because it'd likely require a lot of body modification just to get to where a C5 is stock, to run the tires that a C5 can run naturally.

[Skafrog]

I ran GTS2 and GTS3 for years with the "light is fast" thought. It doesnt work in club racing in reality. I would qualify well, get smoked on the start as the higher HP cars went around me, and then we would parade around under yellow while some idiot had to get removed from the track. Rinse and repeat. Id end up mid pack, unless on the rare times where we stayed green for whole sessions, then it was hard for e46s and e36s and such to keep up. All my info is old as dirt now, but nothing is wrong with a 4 lug, just get custom wheels made. Run a massive kit with AP radi-cal calipers and j hook discs. Get a huge wing from AJ Hartmann, fab up your own splitter, run some underbody aero, throw in an 8HP, MaxxECU for the motor so you also get traction control and MK60E5, and it probably wont do bad. My car will run a high 1:37 or so at Road Atlanta on 200TW tires running a junkyard 2.8, old school ABS and no 8HP, so who knows if something like a 1:35 or so would be competitive.

[FredK]

That's very helpful, Skafrog. I didn't really think about the drag race to the first turn, but that totally makes sense.

[craz azn]

Keep in mind there are modifiers for having massive aero, as well the trans swap ideas (assuming you follow GLTC rules to a T). Might be better off with a smaller rear wing, and a splitter that doesnt protrude out the front to escape some of the aero penalty points.

Look into the Jongblod wheels, i believe they were originally spec'ed for Miatas. They have 15x9s and 15x10s in 4x100. Perfect for 245s.

1.36-37 is right on the money. Pole time this year at RA was 1.35, but probably an outlier as the rest of the top 5 or so was in the 36s. The best e30 in the field was doing 38s.

[Digitalwave]

I'd be happy to help out anybody that is serious about joining the series (not just thought exercise...). Shoot me an email: hey at risingxedge dot com