Stu Davis's 1985 Turbo II Daytona

How do you make a 4 cylinder whip V8's twice it's size? 

By Brad Miller

Editors Note: Stu Davis was/is a powertrain engineer at Chrysler.


Shortblock

1) 1988 Turbo II Short block
2) Forged connecting rods with full floating pins
3) Forged crank
4) High strength pistons
5) Cross drilled block for improved coolant flow to head
6) Honed with deck plate during assembly

Cylinder head

1) Hand ported by Chryslers one and only flow expert
2) 2mm larger intake valves with special profile cut on the underside for increased flow
3) Stock sized exhaust valves with specially cut profiles
4) Head flow is 2-5% BETTER than the "Mopar Big Valve Race Head"
5) Special "Bee-hive" valve springs shimmed to 90lbs for increased lift capabilities and reduced valve float tendencies
6) Roller cam with 1988 profiles for reduced friction and improved low end torque without sacrificing upper end horsepower
7) ARP Customer made head stud kit

ARP makes head studs for the 426 Hemi - bullet proof. Four sets were made using 11x1.5 metric thread to go into 2.2 block with SAE threads on top. Stud kit is 4 times stronger than Mopar Performance kit - - which is actually softer than stock head bolts.

Other stuff's!

McCord Perma-Torque Head Gasket
56mm throttle body
Ported exhaust manifold
Injectors - 20% plus units

Turbocharger & exhaust system

Mitsubishi hand built turbo, Exceeds flow specs of "Super 60" turbo by Mopar Performance, low inertia turbine assembly for faster spool-up, reduces turbo lag. Improved bearing system - turbine spins at 12,000 rpm at idle vs. 0 rpm for Garret turbos. All components required in case of re-build are available

2.5 inch 304 Stainless steel exhaust system with all mandrel bends. Disconnectable via over-center disconnects at pre-catalyst and pre-over the axle bend. $1100 worth of work

Engine calibrations included

1) 12 PSI on 93 octane (13.7 estimate 1/4 mile)
2) 14 PSI on 104 octane (mid 13's estimate 1/4 mile)

Mobil I synthetic oil

A555 (Turbo II) Transmission with 3.87 final drive, GETRAG gearset

Centerforce II Clutch and pressure plate

Goodyear Eagle VR50 Unidirectional Gatorbacks. 225-50R15's

So - - how is the "real" world performance? Well, using the old calculator, we wing it and put in an estimated 275 horsepower, and 3060 lbs of car weight . . . and viola an estimated quarter mile time of 13.00 seconds at over 104 miles per hour. Of course - - that's theoretical numbers based upon mathematical calculations. To date, the car has ran a best of 15.03 at over 96 mph. That equates to 180 horse to the ground based on ET and 211 based on mph. Those runs were done in near 95+ degree heat at noon! Obviously we've got a LOT of wheel spin . . . especially on the 205-60 Defenders (?!) that I'm running now. That will change with the 225-50's though.

The car is VERY quick - - in fact in 3rd gear I can squeeze the throttle and hear the tires breaking loose under acceleration! 1st-3rd at the drag strip is almost a waste with street tires. The key for this car will be to get the stickiest rubber and the most of it to the ground. With mph ranges in the 96+ the car should be good for mid 14 second runs. Lose some weight out of the car and it could be in the 13's . . . but keep in mind that this car is completely intact. It hasn't been gutted (interior removed for weight) in any way, and to look at the car, you wouldn't even suspect that it's got well over double the horsepower of a stock 1985.

The key words to sum up the car are best expressed by a guy I took for a ride recently. He owns a 1992 Daytona with 16" pumper style wheels and a 2.5L Turbo I automatic. The first words were "Holy @!%$ing sh*t - - this thing really moves!" as he was pinned back in the seat. This is why I own this car. Oh - - did I mention that even with the 93 Octane chip, it still gets 30+ mpg?

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