track car 3.6 rebuild options
 

i have an '81 SC track car with '95 3.6 motor (110k miles)and 915 LSD trans, and not much else. the motor is stock except for exhaust headers, cold-air intake and performance chip. '87 turbo brakes and hubs, stiffened suspension and bushings, fuel cell, roll cage and recent convert to RSR style widebody (18x12 rear / 18/10 front rims) and weighs about 2450 lbs. the car is a dedicated DE that is durable, dependable and fairly quick but I am looking to move up a notch w/o sacrificing reliability or budget. I want to continue to burn 93 octane and change oil and brake fluid between track events. i have a rebuild budget of about $10k.
so here's the question:

what can i do to the motor / trans that will provide reasonable performance increase without going full race.

would trans rebuild / re-gear provide better results than motor rebuild.

your thoughts are appreciated

thank you

Wayne Capwell

You can be fast, reliable or cheap. Pick two. Seems to me, at that price point, losing weight is the best option.

How much of the work can you do yourself?

How far your budget will go will largely be determined how much work you can do yourself and by the state of the engine i.e. what can be reused. Unfortunately you can't tell until you start tearing it apart and inspecting components.

A top end rebuild with hotter cams, valve springs, studs and a retune could easily blow your budget if you're paying someone to do everything, and that's assuming P&Cs, rockers and other hardware can be reused.

I'm not familiar with 915 ratios so will let others comment.

op- any pictures of the car? weight loss and suspension make a huge difference- more seat time is a huge win as well!

thank you for your comments. i will post some pix after our Nov DE at VIR. here is some more info. i've been a DE Instructor for several years and attend 6-10 track events a year. while still running the torsion bar suspension, stiffness has been addressed. current hp is about 250 in a 2500 lb car. the car handles well and should be better in the new widebody configuration. realizing my budget is limited, the basic question is whether new trans gearing will make more difference than trying to bump hp to 300+ range and still have a reliable, low maintenance motor.
thank you all

my 3.6 after rebuild dynoed at 305 hp with john dougherty ss grind cams, wong chip, 993 headers. Any higher hp than that and you have to do headwork/larger valves.

A stock 993 2.6 is a relatively torquey unit

Here's a comparison of a typical healthy 993 non vram motor in a 911 chassis w/ 915/61 trans compared to a blue printed open exhaust 3.0 SC club race engine, 1 & 2 are throwaway gears most places so ignore them, the money gears are 3-5
http://forums.pelicanparts.com/uploa...1415312285.gif

this 3.0 could actually profit from a little taller gearing in 4 & 5 to eliminate the tails that fall below the previous gears torque curve, the 993 doesn't have that problem excpt for a tiny bit in 5, 4 could maybe be a teensy bit shorter to eliminate the jump from 3 to 4, but all in all it's not worth the effort

a relatively cheap performance mod for a 993 is to go w/ RS cams if the stock lifters are used or even better SS cams w/ solid lifters

Getting the cam timing perfect is also good for a few hp, most are off on one or both sides, it helps to backdate the cam drives if you don't already have the older pin style.

JonT and Bill - thank you!. Jon-exactly what i was looking for regarding specific hp improvement. Bill- excellent info and real justification for my decision to drop in the 3.6 instead of building out the 3.0. i will definitely look into the cams and lifters over the winter
thank you - this group is an amazing resource and wealth of knowledge