Project "Fiat V-Spec" Design notes, etc

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  Engine pictures  / Design notes 2

Miscellany
Last updated Thursday, November 19, 2009

Misc. sites used for references, ideas, etc
V-8 MGB project / SGP racing

Currently mulling over wheel and tire sizes, and hoping (although seemingly unlikely at this point) we can manage 245/45-16's which would dictate 16x8. Option 2 is Kosei K-1 16x7.5 in a 40+mm offset and running 225/50-16.

Q: Will your suspension be like Mike Spreadbury's (now Gary Savage's - www.datsuns.com/savage) "Strutless wonder"? A mix of multiple manufacturer's parts?

A: That car actually gives me the confidence to try what I'm doing. My 510 is also many different models mixed together. This time around my suspension will be *mostly* custom fabricated. Ron really knows his stuff and will "spend more time designing the geometry on the computer than actually building it" (his words). He has mentioned using late model Corvette spindles as apparently they're standalone - meaning you can design a suspension and have whatever spindle angle you want.

Ron's other orders "Get the wheel most positive offset you can, this will enable us keep scrub radius low and give us room for various king pin angles, etc". Yes SIR!

Q: How much do you think it will weigh after this?

A: As the car sits now it's 2500lbs. I guess 25# each for the turbos, and 25# more for plumbing, intercooler etc, so that's 2575#. The front suspension will be lighter, as the 510/Z struts are HEAVY - the complete assembly is 50# PER SIDE (without wheel). So I'm guessing we'll save 12.5#/side (because it comes to a nice 25# total save), so we're at 2550#.

I'm sure there will be miscellaneous stuff like chassis stiffening, etc which will add another 50#, so presto, 2600lbs. Assuming 100% of it goes on the nose (likely) that moves my F/R bias to 1475/1125 (from 1375/1125). This is 56.7%F/43.2%R. Absolutely HORRIBLE by 510 standards! For comparison, stock is closer to 52/48, and current is 55/45. But ya know what? I figure if a nose heavy FWD car (Type-R) can handle great with good suspension design, why not a nose heavy RWD car? Theoretically I'm only giving up acceleration traction compared to a nose heavy FWD car, but I have enough power to overcome that "limitation". A Mustang Cobra is 57/43 and they pull high G numbers with those. So I figure a 400hp late-model Mustang Cobra that went on a 700lb diet, got squared off and inherited better front suspension geometry is what I'll end up with. This, and it'll say NISSAN on the powerplant :-)

I get the question - and you may be wondering this as well - "How are you going to get all that power down?"

Checking out more dyno charts, I see the DETT has more torque than my DE even as low as 1700rpm, or basically as low as you'd care to load an engine. (The TT listed here is a "Stage III" TT at 12psi)

Check out the chart below:

For one, I plan on changing my effective gearing so there's 16% less torque to the wheels (column 3 reflects this effect at the wheel). With this change, I will still have as much torque to the wheels at 60mph (2100rpm) as I do now with the non-turbo (2500rpm). Also note if I mash it in 5th, by 2500rpm with the turbo motor I will have as much torque as the non-turbo has at 4500rpm!

I'm theorizing between that and 245-section tires I should have livable traction. It'd probably run the 1/4mi a couple tenths quicker with the current setup, but I'm looking for daily-drivable traction more than last-tenth-of-a-second acceleration. I'm also hoping to offset some highway MPG loss. We'll see. I'm also guessing my highway MPG will go from 26-27mpg down to 22-23mpg, but we'll see. A larger fuel tank is certainly in order!

Future plans (don't we all have those) calls for  rear suspension redesign similar to the front, hopefully getting more traction down and then we'll see about gearing down again...

Ready for some REAL geekage? Read on...