Project "Fiat V-Spec" (page 2)

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  Engine pictures / Design notes / Design notes 2

Once you start down the "want more horsepower" path...
So to recap, we have a 1971 Datsun 510 win an Infiniti J30 DOHC 3.0L V6 that makes approximately 230hp (we have dyno'd 187 at the wheels, and assume 19% loss though the drivetrain). We converted it to rack & pinion with a much quicker ratio. The car has been fast and flawless for the last 4 years.

Recently (May 2001) we upgraded the suspension slightly to a coil-over setup up front with 200#/in springs, slightly cut Roadster Competition springs rear (225#/in wheel rate), and Tokico Illumina adjustable strut inserts/shocks at all four corners. This improved the handling immensely and made a wonderful street car, a very decent track day car, and a completely average (yet very entertaining) autocross car.

During this time I had decided I wanted something quite a bit faster. Modding the VG30DE for significant power gains (70-100hp) is a very expensive proposition - camshafts alone are $400 each! The SR20DET has become available and affordable from importers, so I figured a big power (300hp) SR20DET and lighter-than 510 weight (est 1900lbs w/DET)  in a 1200 was the answer. The problem is the 510 has proven to be so very reliable, the OH MYGOD factor of the big VG30DE in the 510's engine bay, and the power everywhere nature of the V-6 took the steam out of the project 1200, so it languished.

2002 rolls around, and I decide it's "fish or cut bait" time with my project - I don't want a multi-year project if all I'm doing is sitting on it. Selling the 510 to have someone finish the 1200 is out of the question. I'm really sold on having IRS, and converting the 1200 to that would be an added expense over the rest of the project. So I send out a long letter to three key partners in crime (one of them Ron Tyler, who basically volunteered to be my builder for the next stage of whatever I decided), and discuss this same topics with my wife, Sara. The condensed version is here:

"Here are six options - one of which I will follow to conclusion this year.
1) Sell the SR20DET and highly modify the suspension of the 510, staying satisfied with current power
2) Put the SR20DET into the 510 (dropping 100lbs and adding 70hp), massive change to 510 suspension
3) Sell SR20DET, turbo the V-6, massive suspension change
4) Sell SR20DET, sell VG30DE, drop in VQ35DE, massive suspension change (add 40hp, drop 50lbs)
5) Sell SR20DET, keep the 510 as is, do V-8 Z-car (unbeatable HP/dollar ratio, easy swap)
6) Finish the 1200 project (or rather, have RON finish it).

#3 Won out by a 3-1 margin. The SR-into-510 was ruled out because so many are doing it nowadays, power-everywhere is addicting, the VG is already in there, and the wow factor is much higher with the V-6.

Initially option 3 in my mind was grabbing VG30DET (single turbo) parts and boosting (6-8psi) the current engine. Ron said he'd prefer a TT setup as it would fit my uses better (keeping more low RPM power). This opened up the path to the VG30DETT which as you may know, came in the '90-'96 300ZX Twin Turbo and therefore a very proven power upgrade path.

Oddly enough, my expected power/weight is STILL projected to be worse than the 1200's (6.75lb/hp vs 6.2lb/hp). Overall cost will likely be similar, but the suspension underneath should be MUCH better suited for the power/weight expected. Also drivability should be equal to now as the TT engine surpasses my nonturbo motor at a low 2000rpm. Also, here's an interesting comparison between a 317hp SR20DET and a 310HP VG30DETT.

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